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MODEL OF VARIABLE FUZZY SETS AND ITS APPLICATION TO
CLASSIFICATION PREDICTION OF ROCKBURST

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2005, 24 (S1): -4603 doi:
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[PDF 291 KB] (829)

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The occurrence and intensities of rockburst are influenced by various factors and the influence degrees of these factors vary with different projects. To evaluate the various factors on rockburst，the concepts，definitions and methods of variable fuzzy sets are established based on fuzzy sets theory. Then，the formulas of difference functions and relative membership degree，model of BP neural network with fuzzy optimization，equation of rank feature values are presented，and relevant equations are analyzed. On basis of indexes standard intervals of rockburst with a series of underground rock projects in home and abroad by the presented methods，occurrence and intensities of rockburst with rank feature values are predicted. The predicted results agree well with the practical records，which shows that the proposed method is effective.

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DISCUSSION ON EVOLUTIONARY LAW，ATTENUATING CHARACTERISTIC AND CALCULATING METHOD FOR THE
SHEARING STRESS OF THE SECOND INTERFACE OF
ANCHORAGE TYPE STRUCTURES

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2005, 24 (S1): -4610 doi:
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[PDF 378 KB] (1049)

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Research on the distribution，evolutionary law，attenuating characteristic and action mechanism of the shearing stress for the second interface of anchorage type structures is the basis and precondition for scientific and reasonable design of anchorage type structures. At present，all internal and external technical standards adopt the concept and method of average shearing stress for engineering design. This may cause disadvantage and potential risk. The internal and external research states are discussed since the 1960s for this problem. The results show that it is necessary to study this problem thoroughly.

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CALCULATION METHOD OF ACTIVE EARTH PRESSURE BASED ON CSA AND THIN-LAYER ELEMENT METHOD

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2005, 24 (S1): -4627 doi:
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[PDF 297 KB] (987)

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The influences of earthquake amplitudes，frequency and duration time on the different rock cavern displacements are primarily studied by using FLAC3D. It is found that the displacements of rock cavern clearly increase with the increasing earthquake amplitudes and duration time as well as the decreasing frequency. The changing rates of displacements with the above earthquake parameters decrease with the increasing overburden and in-situ lateral coefficient (l). It is also indicated that under shallow overburden，the threshold earthquake intensity probably exists. When the earthquake intensity reaches up to the threshold value，the cavern displacements significantly increase with the increasing earthquake amplitudes. In addition，it is revealed that the low frequency properties of earthquake have clear influence on the cavern displacement，and the cavern displacement under earthquake with low frequency is obviously larger than that at high frequency.

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EFFECTS OF GEOLOGICAL STRUCTURAL FAULTS ON BLASTING SEISMIC WAVE PROPAGATION

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2005, 24 (S1): -4635 doi:
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[PDF 238 KB] (1052)

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A simple model of blasting seismic wave propagation in weak layers is presented according to the characteristics of geological structural faults. The decay rules and formula of blasting seismic wave propagation in weak layers are obtained by using the viscoelastic theory. The decay effects of the blasting seismic wave are investigated with the frequency of seismic loading and parameters of structural faults.

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EXPERIMENTAL STUDIES ON HORIZONTAL DRILLING HOLE BY WATER JET IN COAL SEAM

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2005, 24 (S1): -4642 doi:
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In order to study the acoustic wave propagation properties and the ratio of dynamic elastic moduli to static one for unloading rock mass of Three Gorges Project，based on the results of the acoustic wave measurement on the unloading rock mass in the digged slope of the Three Gorges Project，firstly the propagation characteristics of the acoustic wave in rock mass are studied，and the testing results of acoustic wave method are obtained. Taking the ideas and methods of unloading rock mass mechanics，the results of acoustic wave measurement are analyzed and the corresponding changing laws of acoustic wave in different directions and the different wave speed at different altitude of unloading rock slope，which have obvious orthogonal-anisotropy characteristics，are gained. Then different unloading regions are classified based on the propagation characteristics of the acoustic wave，and the macro-mechanical parameters of unloading rocks of each unloading region are determined. Finally the relation between stress and strain in triaxial unloading test is given，and the relation between the relative elasticity modulus Ei and L gained by the finite element analyses is listed. Comparison between the results of the acoustic wave measurement and those of experiment shows good agreement.

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NUMERICAL SIMULATION ANALYSIS OF NONDESTRUCTIVE
DETECTION OF STRESS WAVE IN ANCHORAGE BOLTS

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2005, 24 (S1): -4647 doi:
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[PDF 425 KB] (1120)

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Nondestructive detection of stress wave in anchorage bolts is a kind of quick and effective detection method. In this paper，bolt and mortar in anchorage system are appreciatively considered as isotropic materials. Applying composite material theory，equivalent one-dimensional physical and mechanical model of bolt and mortar is founded and equivalent engineering parameters are determined. Based on one-dimensional wave theory，the propagation equation of stress wave in anchorage system is induced. The numerical simulation of flaws in anchorage system is carried out. Through adjusting the coefficients of the dominant equation，the dynamic response of defective anchorage system under impact load can be simulated. Through comparing and analyzing，it is shown that the simulated curves are in good agreement with the waveforms obtained from model test measurements. Analytical results in theory can preferably reflect the actual dynamic character in bolt. Consequently，the mode，exciting force function，the equivalent parameters and the results of numerical simulation are proved to be correct and effective. It will play an important role in increasing the accuracy of detection results.

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STUDY ON THE MECHANISM OF JOINTED ROCK MASS LOOSING INDUCED BY DYNAMIC UNLOADING OF INITIAL STRESS
DURING ROCK BLASTING

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2005, 24 (S1): -4653 doi:
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[PDF 283 KB] (1155)

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The viewpoint that the process of the initial stress unloading in rock mass during blasting is a dynamic process is brought forward，and the theory of stress wave and propagation is employed to analyze the movement process of the rock block under the sudden unloading of the initial stress during rock excavation by blasting. The results show that，under the condition of sudden unloading of initial stress，a rigid body displacement could occur，besides an elastically reverting displacement，which will lead to the opening of the jointed rock faces and the loosing of the rock mass. If the initial stress is high enough，the induced horizontal displacement of rigid body will be much larger than the elastically reverting displacement. The calculated results also show that the opening displacement of the jointed rock face is approximately proportional to the square of the value of the initial stress. The process of the dynamic unloading of the initial stress can be employed to explain the mechanism of the loosing of jointed rock mass during rock excavation by blasting.

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EXPERIMENTAL STUDY ON DYNAMIC CONSTITUTIVE CHARACTERISTICS OF ANTHRACITE OF YUNJIALING COAL MINE

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2005, 24 (S1): -4658 doi:
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[PDF 272 KB] (964)

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Impact experiments for anthracite of Yunjialing coal mine are performed on split Hopkinson pressure bar(SHPB) equipment with a large diameter of 75 mm. Generally，dynamic stress-strain curve for this kind of anthracite has four stages which are nonlinear beginning load stage，plastic yielding stage，strengthening stage，and the last unloading breakage stage. Correspondingly，dynamic stress-strain curve has three characteristic parameters，which are the beginning modulus，yield strength and ultimate strength；and all of them go up with strain rate，but yield strength has best correlativity with strain rate. Plastic yielding is the most remarkable character of anthracite under uniaxial dynamic compression.

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SEPARATION CHARACTERISTICS AND MECHANISMS OF
LAMINATED COMPOSITE ROOF STRATA OF LONGWALL ROADWAY

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2005, 24 (S1): -4663 doi:
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[PDF 296 KB] (900)

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Based on a separation dataset collected from a comprehensive underground monitoring in a coal mine in Australia，this paper presents the theoretical and analytical work on the roof separation characteristics，propagation and mechanisms of laminated weak strata of longwall roadway associated with different mining activities including stages of heading development，time-dependent，and longwall extraction. Analytical result indicates that roof separation and propagation are strongly related to different stages of mining activities，such as stress concentration and re-distribution in the stages of development and extraction and roof rock degradation and soften in the stage of time-dependent, and each stage involves different separation characteristics and mechanisms. The monitoring data also suggested that the major separation originated almost uniformly with the formation of opening from the roof surface up to 6 m upwards，and then two separation zones were formed in both lower roof strata in coal and upper roof strata in mudstone respectively. The two separation zones subsequently emerged gradually，and the merged separation zone covered from roof surface up to 6 m which is two times of the heading height. The results indicate that the mechanical characteristics of individual roof layers such as weak claystone layers，water effect on mudstone layers and the interface between the layers，as well as the levels of vertical and horizontal stress in pre- and post- stages of mining activities are important factors involved in roof separation mechanisms and control roof separation and propagation process.

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REAL TIME CT TESTING ON DAMAGE EVOLUTION CHARACTERISTICS OF FROZEN CRACKED-SANDSTONE UNDER UNIAXIAL COMPRESSION

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2005, 24 (S1): -4670 doi:
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[PDF 243 KB] (981)

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The CT testing study on meso-damage propagation characteristics of frozen cracked-sandstone with double man-made cracks under uniaxial loading using the CT special testing system is accomplished. The CT images and CT number in different stages，including micro-crack birthing，development，marco-crack birthing，and sample failure，are obtained. It shows that，compared with the frozen intact rock sample，the man-made crack can seriously affect the location of new crack generation and the formation of connectivity macro-crack of frozen cracked-rock sample. Because of the man-made cracks existing，the volume expansion values of the frozen cracked-rock sample under uniaxial compression are large than those of the frozen intact rock sample.

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STUDY ON BLAST-INDUCED BEDROCK DAMAGE EXTENSION
FOR A NUCLEAR POWER STATION PROJECT

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2005, 24 (S1): -4674 doi:
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[PDF 193 KB] (1009)

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Four groups of sonic wave tests have been performed in the bedrock blasting excavation at the Ling¢ao nuclear power station project of Guangdong Province，China. The changes of sonic wave speed before and after the detonation are obtained. Based on the relationship of sonic wave changing ratio and the critical damage parameter，the damage extention of each blast and sonic wave test is determined. It is found that surrounding rock in the depth of charging section is the most seriously damaged. In the area adjacent to the ground and beneath the bottom of the charge hole，the rock is less damaged under blasting. The damage parameters and depth under the bottom of charge holes increase clearly with the decreasing distance from the donation. It has also been observed that the horizontal damage distance of rock under explosion is approximate 3 times of the damage depth. The blast-induced damage extention distinctly increases with the single charge weight.

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THE STRUCTURAL HIERARCHY VISCOSITY AND
DYNAMIC STRENGTH OF ROCK MASSIF

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2005, 24 (S1): -4679 doi:
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[PDF 405 KB] (1084)

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Rock mass posses complex structural hierarchy. Such structural hierarchy involves a very wide range of scale levels from atomic scale level to tectonic scale level. This situation makes the concept of elementary volume and Saint-Venant¢s deformation compatibility condition used in continuum mechanics problematic. Internal structural hierarchy influences viscosity and dynamic strength of rock mass，but until now studies haven¢t been seen to link viscosity and dynamic strength of rock mass on different scale levels. This paper，based on the available investigation data and physical mechanical theories，studied the relationship between the viscosity，dynamic strength and the structure hierarchy of rock mass. It is shown from the study that different hierarchy levels correspond to different strength，viscosity and deformation rate. Macroscopic hierarchy scale level corresponds to low strength，low deformation rate and high viscosity，micro-macroscopic scale levels share high strength，high deformation rate and low viscosity. Generally，with the increase of the external loads and the deformation rate，the deformation and fracture consecutively involve macro-，meso-and microscopic levels，correspondingly dynamic strength increases，and viscosity decreases gradually. In moderate and high deformation rate region，dynamic strength increases substantially；viscosity is inversely proportional to deformation rate. Hence strength and viscosity are not constants for one material，but have different values on different hierarchy levels. As for the size of fractured rock，it is related with the dynamic strength which rock mass can reach. Based on the analysis of mechanical behavior of rock mass on different hierarchy levels，approximation formulae for the dynamic strength and viscosity in dependence on hierarchy levels and deformation rate，formula for the determination of fractured rock mass are suggested.

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MATHEMATICA ALGEBRA SYSTEM AND DEDUCING THEORY OF GEOTECHNICAL ENGINEERING

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2005, 24 (S1): -4688 doi:
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[PDF 321 KB] (1255)

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The second algebra system Mathematica is used to deduce analytical solution in some theories of rock engineering in this paper. The method，for example，takes the soil and the pile as a whole system (visco-elastic half-space embedded pile).Using the method of the continuum mechanics，the nonlinear visco-elastic pile-soil mode is established. Assuming that the pile is a Euler beam with circular cross-section，the visco-elastic material and the soil are composed of two parts：an outer infinite linear visco-elastic zone and an inner nonlinear visco-elastic zone (hollow cylinder). In the three-dimensional cylindrical coordinates，the boundary value problem and joining condition are presented. The computer with the system Mathematica goes through the four main processes of symbolic operation，numerical calculation，plotting and programming. The results of this method agree well with Novak¢s results.

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A PRELIMINARY INVESTIGATION ON THE INTERACTION MECHANISM OF ROCKS AND SHORT PULSE LASER

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2005, 24 (S1): -4694 doi:
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[PDF 933 KB] (1115)

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_{In the petroleum exploration，the technology of hydraulic fracturing or perforating charges is used to increase the permeating velocity of petroleum in natural rocks. However，there are limitations for both of these technologies. To probe a new concept technology of petroleum exploration，i. e.，laser technology is applied to increase the permeating ratio of natural rocks，some preliminary experiments are conducted to investigate the responses of granite，marble and red stone in the states of natural，water-saturation and oil-saturated under the shock of short pulse laser. The 3D contour of ablation pit and the preliminary relations of the ablation contour and the number of laser pulse are obtained. The results show that some cracks generate at local place for the shock of laser，and the degree of ablation of the oil-saturated rocks is more serious than that of the natural and water saturated rocks. However，further work should be conducted to control the direction，sizes and number of cracks generated under the shock of laser.}

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IN-SITU EXPERIMENTAL STUDY ON TRANSMISSION OF BLASTING
VIBRATION WAVE IN GROUPS OF TUNNELS UNDER COMPLICATED CONDITIONS

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2005, 24 (S1): -4700 doi:
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[PDF 291 KB] (917)

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During the construction of Xiluodu hydroelectric station，three parallel training tunnels with great height and span shape are excavated in the right bank，and those tunnels are close with each other. It is inevitable for many work faces to operate at the same time. Thus，the important problem of safety is presented by blasting interference and complicated constructing conditions. Based on maintaining stabilization of rock mass and reducing the cost of support，in-situ experiments of blasting vibration are carried out in the groups of tunnels. According to test data，the rules of transmission of blasting vibration wave are studied in the excavating own and adjacent tunnel. The results show that there are some differences in the rules of transmission of blasting vibration between own and adjacent tunnels when excavating own tunnel，in which the vibrating velocities of particles in the adjacent tunnel hold magnifying effect. Moreover，the velocity magnifying effects between inside and outside walls of the adjacent tunnel are different，and the velocity magnifying effect of inside wall is weaker in the near zone and stronger in far zone compared with the outside wall. The studying results offer the guidance to the construction and design of complicated groups of tunnels and will be useful for the similar projects.

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INFLUENCES OF EXPLOSIVE VIBRATION IN OVERLAPPING TUNNELS ON ADJACENT STRUCTURES

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2005, 24 (S1): -4705 doi:
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[PDF 247 KB] (866)

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The overlapping tunnels in a subway project are considered as the study background，and the influence of explosive vibration in overlapping tunnels on adjacent structure is studied during the subway project construction. The explosive vibration loadings are obtained by analyzing acceleration of explosive vibration. The initial stresses after excavation are calculated with stress relaxation method. The rational time step and damping of vibration analysis are defined by vibration modes and frequencies that are obtained with modal analysis. On the basis of Newmark step-by-step time integration method，the dynamic response of overlapping tunnels caused by the explosive vibration is analyzed. The stresses，displacements，and weak portions in the liner are determined under vibration loadings and static loadings. The vibration parameters and attenuation values in ground are achieved，and the results can be referred to tunnel design.

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APPLICATION FOR MONITORING LARGE BLAST AFTERSHOCKS BY MULTI-CHANNEL MICROSEISMIC MONITORING TECHNOLOGY

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2005, 24 (S1): -4711 doi:
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[PDF 269 KB] (1067)

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Aftershocks of large blasts in mining stopes can be used to evaluate the stability of country rockmass around deep stopes with high stress. Occurring times and ratios of aftershocks are significant indices to judge the stability of country rockmass. Real-time and spatial location monitoring of aftershocks of large blasts by a 16-channel full-digital microseisimic monitoring system at deep mining stopes at Fankou Lead-zinc mine are carried out to determine the occurring times and the positions of the aftershocks. The monitoring results show that sometimes there are no aftershocks and sometimes aftershocks happen after large blasts. All the aftershocks，which occur after large blasts，take place within several minutes. If no events occur in 30 minutes after large blasts，it means the surrounding rockmass has a good stability.

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EXPERIMENTAL STUDY ON ELASTIC MODULUS OF LIME
SOIL UNDER DYNAMIC LOADING

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2005, 24 (S1): -4715 doi:
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[PDF 245 KB] (1015)

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Based on a lot of dynamic triaxial tests，the variation laws of dynamic elastic modulus of lime soil sample were studied. Meanwhile，the influences of lime dosage ratio，consolidation ratio，and frequency on elastic modulus were investigated. It is concluded that the relationship between elastic modulus and dynamic strain of lime soil is similar to that of natural soil. The elastic modulus increases as the confining pressure increases at the same level. With dosage ratio increasing，the elastic modulus also increases，and when it exceeds 5%，the elastic modulus increases evidently. The influence of consolidation ratio on modulus is significant. At a lower strain，the modulus increases with the consolidation of ratio increasing. When strain exceeds a certain value，the modulus decreases with consolidation ratio increasing. The higher the frequency is，the larger the modulus is. But the influence of frequency on modulus is not as evident as above factors. It is verified that the way to adopt the soft soil of unfavourable mechanical properties by adding lime as road fillings is economical and practicable. The achieved conclusions can provide a useful guidance for the preliminary estimation of lime requirements to improve the dynamic properties of clays.
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EFFECT OF FORMATION ORTHOTROPY ON CASING STRESS

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2005, 24 (S1): -4720 doi:
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[PDF 394 KB] (986)

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Casing damage is the bottleneck problem for oil and gas production. Reasonable design of collapse load is vital to the life of casing. Former researchers considered the formation to be orthotropic and transverse isotropic. But the rock mechanics orthotropy in the plane perpendicular to well axis is not taken into account. Based on this point，the mechanics and finite element models for casing stress calculation are established. The results show that casing stress presents uniform distribution situation if the formation is transverse isotropic with the uniform horizontal in-situ stress. If the formation is orthotropic，however，the casing stress becomes non-uniform distribution. At the same time，the maximum casing stress is larger than the former. So it is obvious that the formation orthotropy has great effect on the casing stress，which should be considered in casing design process. This conclusion is also helpful for explaining the question that casing collapse load maybe larger than the overburden stress some times. When the horizontal in-situ stress is non-uniform，the casing stress is non-uniform at all times not only in the isotropic formation but also the orthotropic ones. At the same time，the maximum casing stress is almost same to each other. Therefore，under this condition，the rock mechanics orthotropy problems can be overlooked during the casing design process.

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STUDY ON STRESS SENSIBILITY OF ROCK PERMEABILITY BASED ON PRESSURE WELL TEST

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2005, 24 (S1): -4724 doi:
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[PDF 157 KB] (1058)

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Relationship between permeability and stress is the key foundation for coupled seepage-stress analysis of rock mass. Based on the seepage pressure well test and rock mass physical and mechanical properties，the permeability and stress in rock slope of Longtan hydroelectric station are achieved. By analyzing the data，the relation between permeability coefficient and geo-stress is presented，and a key material for fluid-solid coupling analysis is provided.

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EXPERIMENTAL STUDY ON DAMAGE TO SURROUNDING ROCK MASS BY CONTOUR BLASTING

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2005, 24 (S1): -4728 doi:
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[PDF 237 KB] (742)

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Rock damage from blasting should be minimized as possible. In order to reduce the blasting damage to the surrounding rock mass，it is urgent to find the law on blasting damage to the rock affected by blasting parameters through model experiments. Based on this point，the experimental technique and measurement method are proposed and the results from the experiment under various perimeter-blasting parameters are analyzed. The law on the distribution of damage factor affected by perimeter blasting parameters is discovered，including decoupling coefficient，burden，firing time interval，and blast hole stemming and etc.. The findings in the experimental study are significant for blasting practice in engineering，parameter optimization and in-depth study of contour blasting theory.

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THE STUDY AND COMPARISON OF THE MECHANICAL PERFORMANCE OF MARBLE UNDER THE ACTION OF HIGH TEMPERATURE AND CIRCLE HIGH TEMPERATURE

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2005, 24 (S1): -4735 doi:
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[PDF 225 KB] (1003)

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The stress-strain behaviors of marble taken from F8 fault-age zone of Luohu Jiancheng district in Shenzhen under the action of temperature from normal temperature(20 ℃) to high temperature of 800℃ and cycle temperature of 100 ℃ to 700 ℃ (repeated 8～9 times) have been investigated by hydraulic pressure servo rigidity rock mechanics experiment system MTS815.03. Influences of the high temperature and high circle temperature on peak strength，post-peak characteristics，deformation characteristics are analyzed and compared systematically. It is shown that the elastic modulus and strength decrease when the samples suffer high temperature，at the same time the strain increases when the peak strength appears；the sample which suffers temperature lower than 400 ℃ generally have the characteristics of brittle failure and the sample which suffers temperature higher than 400 ℃ have the characteristics of plastic collapse，and gradually the peak strength appears unclearly. Comparing the two kinds of experimentation，a conclusion can be drawn that the marble peak strength and elastic modulus under the action of circle temperature are lower than those under the action of corresponding temperature one time and the higher the temperature is，the more obviously the strength decrease and the characteristics of plastic collapse appears.

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STUDY ON ACOUSTIC WAVE MEASUREMENT AND MECHANICAL PARAMETERS OF UNLOADING ROCK MASS OF THE
THREE GORGES PROJECT

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2005, 24 (S1): -4740 doi:
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Three jet stages in the flow structure and the rock fragmentation mechanism of strike，impact，water wedge，cavitations erosion，cutting of water jet，and the course of rock fragmentation，are analyzed. The frontier problems of rock fragmentation by water jet at present are studied，where it is suggested to study the course of rock fragmentation by water jet from the angle of the coupling effects of water jet and rock and effects of the dynamic fragmentation of rock. A new scheme of drilling a hole by a high pressure water jet in the coal seam is put forward. A continuous steel pipe twisting on a roller connects the water jet bit with the high pressure water pump，and a continuous drilling job in the coal seam can be performed，which is of drilling automatism and can quicken the drilling. The nonlinear relation between the pressures and the distances of water jet through the test datum and the delivery samples of the drilling slag are analyzed，and it shows that the slag particle by the water jet drilling is larger than that by the ordinary drilling. The conclusions are drawn that it has a critical pressure of rock fragmentation by water jet，and that the pressure and the flux of water jet have nonlinear correlative laws with the efficiency of rock fragmentation. Compared with the flow rate，the water jet pressure plays a more important role on the rock fragmentation.

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PREDICTION METHOD OF ROCK BURST BASED ON MICROSEISMIC MONITORING AND STRESS FIELD ANALYSIS

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2005, 24 (S1): -4745 doi:
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[PDF 221 KB] (1742)

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The international and domestic conditions of rock burst occurrences are summarized，and the development states of monitoring technique of rock burst are analyzed. It is found that rock burst occurs frequently as the mining depth increases and the influence scope of rock burst expands extensively. At present，there is not a valid monitoring technique and analyzing method，which can really forecast rock burst occurrence. For the purpose of the rock burst¢s prediction，the geophysical method is introduced；and the mine microseismic monitoring analysis system(MMAS) is proposed，which is composed of the microseismic monitoring system and numerical analysis system. The microseismic monitoring data，which is obtained by the microseismic monitoring system，can be transmitted by the internet to the numerical analysis system. Meanwhile，the data exchange between the monitoring system and the numerical analysis system can be implemented. By using the large-scale scientific calculation，the stress buildup，stress shadow，and stress transference of the stope，which is induced by the mining activity，are analyzed；and the rock burst occurrence is predicted. Meanwhile，the mine MMAS can also be used to predict other dynamical disasters of rock engineering.

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STUDY ON EFFECTS OF DYNAMIC UNLOADING ON INITIAL
STRESS DURING ROCK EXCAVATION

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2005, 24 (S1): -4750 doi:
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[PDF 232 KB] (1339)

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The concept of dynamic unloading of initial stress of rock mass in the excavation process of slope and underground powerhouse is presented. Taking the excavation of underground powerhouse of Longtan hydropower station as an example，the influences on rock mass induced by blasting load and dynamic unloading of initial stress are compared. The results show that the high dynamic unloading of initial stress during rock excavation may be an important factor inducing looseness of rock mass. Damage in neighboring field of hole is mainly caused by blasting load，but damage in far field of hole may be induced by dynamic unloading of initial stress during rock excavation，i.e.，the higher unloading rate of initial stress is，the lager the loose zone of surrounding rock mass is.

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PREDICTION METHOD FOR WILDCAT WELL ROCK
DRILLABILITY BEFORE DRILLING

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2005, 24 (S1): -4755 doi:
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[PDF 215 KB] (903)

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The rock drillability is an important index for optimizing bit selection and programming drilling parameters. Prediction of rock drillability before drilling is very important for the increase of drilling efficiency and the reduction of drilling cost in deep wells or super-deep wells. Nowadays，at home and abroad，there are few reports about how to predict rock drillability of wildcat well before drilling in new exploration area. For wild well，there are lack of logging data and core data. Therefore，present evaluation methods of rock drillability can not be applied to predict rock drillability of wildcat well before drilling. Based on the selection of similar structure，a method for predicting the rock drillability of wildcat well is proposed. GA-BP (genetic neural network) model is established by use of seismic data，logging data and core data of the similar structure well. On the basis of neural network theory，genetic algorithm is used to optimize neural network. According to seismic data，rock drillability of wildcat well will be predicted before drilling by use of this GA-BP model. Rock drillability for Xinjiang well MX1 is predicted before drilling. Compared with evaluation results of logging data，average relative error of the prediction result is 9.8%. The field application result testifies that this method is feasible and has a high accuracy.

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CHECK ON POST GROUTING AT THE BOTTOM OF TEST PILES BY
ULTRASONIC CT

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2005, 24 (S1): -4760 doi:
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[PDF 378 KB] (968)

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The ultrasonic CT is used to check the post grouting at the bottom of the test piles in the being constructed Yangtze River Bridge at Nantong city，Jiangsu Province. The key of the technology is to correctly identify arrive time and to build right criterion to link sonic wave velocity and materials. There are several materials in the checked section，such as concrete，sand and grouting. The materials form several boundaries and lead to complex reflection and refraction. The signal of first arriving may be not the one along the line from ultrasonic emitter to receiver. The correct arrive times are identified by theoretic analysis and practical work. They should also be corrected to eliminate random and system errors，such as inclined drill changing distance between ultrasonic emitter and receiver. To built right criterion to link sonic wave velocity and materials，both laboratory test and in-situ practice should be combined together. The other parts of the checking process also are discussed. It is proved that post grouting at the end of pile can greatly improve the bearing capacity of pile foundation. The rigidity of mixture of cement grouting and sand varies from concrete to common sand. It depends on ratio of cement grouting and sand. If the mixture is not fully concreting at checking，the rigidity of the mixture and the bearing capacity can be further increased.

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GENERANT LAW AND PREVENTION OF PILLAR ROCKBURST
AT HUAFENG MINE

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2005, 24 (S1): -4765 doi:
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[PDF 209 KB] (934)

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Rockburst in coal mine is a disaster which exists all over the world. The geological conditions of mining and the history of rockburst of Huafeng coal mine are introduced in this paper. The generant process of pillar rockburst which occurred in Huafeng coal mine is mainly discussed，and the reasons and characters are analyzed. At last，some prevention and cure measures about how to prevent pillar rockburst during the laneway digging and working face mining are advised. In practice，these measures get an ideal result.

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STUDY ON THE EXPERIMENT OF ROCK BURST UNDER
UNLOADING CONDITION

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2005, 24 (S1): -4769 doi:
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[PDF 206 KB] (1125)

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The behavior of rock deformation and its failure characteristics under loading and unloading conditions are substantially different. Rock burst during excavation of underground engineering in areas of high geostress is a typical failure phenomenon due to unloading. Triaxial unloading tests are conducted in this paper. Rock specimens are firstly compressed in a triaxial cell and then the confining pressure is reduced progressively while keeping the axial deformation constant. Experiment results show that specimens absorb energy during axial compression loading and release energy during failure at confining reduction. Strain energy stored in rock is sufficiently large to cause failure when it is released. To prevent rock burst，one of the basic methods is to release the strain energy in rock before excavation. Pre-boring has been successfully used to release the strain energy and to prevent the rock burst in mines. Rock burst could also be controlled or released by adjusting the speed of excavation.

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ELASTIC-PLASTIC-VISCOUS DAMAGE MODEL OF ROCK MASS
AND ITS APPLICATION TO ENGINEERING

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2005, 24 (S1): -4774 doi:
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[PDF 195 KB] (855)

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Rock mass will be damaged and then fractured further because it is subjected to unloading，and it¢s necessary to consider the damage and creep of rock mass. Taking damage as a component by summarizing and concluding the previous accomplishments and considering damage of rock mass，an elastic-plastic-viscous damage mechanical model is set up，and the constitutive equation is deduced in two different action conditions(If is less than ，the elastic-plastic-viscous damage model of rock mass will be applied，or the plastic-viscous damage model will be applied.). Then，the mechanical characteristics are analyzed，and the corresponding creep curve of rock mass creep damage is given out. Lastly，equivalent modulus of deformation of calculation formula is set up. The elastic-plastic-viscous damage model of rock mass established is applied to the Geheyan engineering and the equivalent modulus of deformation set up is used to calculate the creep of rock mass of high-steep slope in Geheyan power plant. The final creep of this slope is predicted and compared with the motoring displacement. The calculated result is compatible with the trend of the motoring deformation curve though the numerical value has certain differences，which proved the applicability of the model.

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APPLICATION OF WAVELET-PACKETS ANALYSIS TECHNIQUE IN THE SIGNAL DE-NOISING FOR SHPB TEST OF ROCK

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2005, 24 (S1): -4779 doi:
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[PDF 297 KB] (1040)

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In sight of the highly-noised，instantaneous and non-stationary characteristics of signal in SHPB test of rock，the wavelet-packets analysis technique is used to de-noise the test signal. Through compare between the wavelet-packets de-noised signal with that obtained from conventional method，it is found that the results gotten through strain gauge filtering and successive-values-averaging method is inaccurate. Wavelet packets analysis，as a new and promising tool in signal analyzing，has good resolution in time and scale aspects. The technique is used to de-noise signal from SHPB test of rock，the resolution is obtained in time and frequency domains simultaneously in multi-scales，and the de-noised results have neglectable errorness，the results turn out to be more reliable.

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ANALYSIS OF CHAMBER BLASTING VIBRATION BASED
ON HHT METHOD

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2005, 24 (S1): -4784 doi:
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[PDF 340 KB] (1027)

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HHT(Hilbert-Huang Transform) provides a fire-new and predominant time-frequency method in analyzing and processing non-stationary signals. It has characteristics of self-adaptation and good efficiency，and Hilbert energy spectrum can clearly express the energy distribution with time and frequency in detail. In this paper，the data collected from blasting vibration monitoring records on project of engineering chamber blasting with 15 000 t/d in open mine that are carried out by mine company of Luomu group at Lengshui town in Luanchuan county are analyzed with HHT. Time-frequency character of chamber blasting vibration and influence upon vibration propagation characteristic due to different field conditions are discussed.

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EFFECT OF MODEL PARAMETERS ON 3DEC DYNAMIC MODELING

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2005, 24 (S1): -4790 doi:
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[PDF 317 KB] (1462)

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Model parameters have the important effects on three-dimensional distinct element code(3DEC) modeling of the stress wave propagation and attenuation in jointed rock masses as well as other codes. Two cases are simulated as follows：(1) one case shows one-dimensional sine wave propagation along a finite-length rock bar without joint；and (2) the other case shows one-dimensional sine wave propagation along a finite-length rock bar with a single joint. Three-dimensional numerical experiments are conducted to investigate the effects of element mesh sizes，boundary conditions，joint constitutive models，joint normal stiffness and tension capacity on modeling of wave propagation and attenuation in jointed rock masses by 3DEC. The results are obtained as follows：(1) the element mesh sizes have the important effects on the computing accuracy and time consumption；(2) the viscous boundary condition can eliminate the reflection of stress wave on the free boundary；(3) joint normal stiffness and tension capacity influence the wave propagation，and the transmission coefficient increases with the increasing normal stiffness，while reflection coefficient is dependent on the type of wave. Therefore，the reflection coefficient decreases with the increasing normal stiffness for compression wave；reflection coefficient is independent of normal stiffness for tension wave propagation on the joint without tension capacity；and (4) the continuous yielding model has the similar effect on the coefficients of the transmission and reflection with the constant stiffness model without tension capacity.

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STUDY ON CHARACTERS OF STRESS WAVE PROPAGATION
IN FUNCTIONALLY GRADED SOIL

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2005, 24 (S1): -4798 doi:
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[PDF 442 KB] (915)

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The model of wave propagation in functionally graded material(FGM) is introduced to soil medium，and the concept of functionally graded soil medium is brought forward. Combined with the actual conditions and test results，exponential functions are used to express the variation of the shear modulus and damping ratio of the soil with the depth. Then，the motion equations for the transmission of the stress wave are derived and solved by using finite difference method. The ground surface response spectra curves of the model are gained under different depths and different soil media. The comparisons and analysis are carried out under a series of circumstances，and some laws of the influences on above structures are obtained，which can provide some references to the antiseismic engineering.

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DISCUSSION ON EVALUATION METHOD OF BURSTING LIABILITY WITH COMPOSITE MODEL OF COAL AND ROCK

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2005, 24 (S1): -4805 doi:
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[PDF 239 KB] (1099)

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The evaluation method of bursting liability of coal or rock with composite model is summarized and analyzed on the basis of a great deal of experiments in the laboratory. The achieved results show that indexes on bursting liability examined with composite model of coal and rock are larger as compared with single model of coal. According to the results，the composite model is advised to evaluate the bursting liability of coal or rock，considering the characters of frame and cover in point of the layer of coal and rock.

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A REVIEW ON DAMAGE MODEL FOR BRITTLE MATERIALS
UNDER IMPACT LOAD

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2005, 24 (S1): -4811 doi:
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[PDF 204 KB] (1261)

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The damage model of brittle materials under impact load is very important for study of blast，penetration，and collision with high velocity. However，there are many difficulties in such study，which come from two aspects as follows：(1) the complexity of response of brittle materials under impact load；and (2) the difficulty to carry on simulating test and measuring method. Therefore，the research situation and methods of damage model for brittle materials under impact load have been summarized since recent 20 years，and the tendency and existed problems have also been discussed. The variables of damage model directly determine the level (macro-，meso-，and microcosmic level) and the basic method. Accordingly，the current damage models that describe the mechanical response of brittle materials under impact load are classified according to different damage variables，and the developing tendency are also commented.

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LOCALIZATION OF SATURATED BRITTLE ROCKS UNDER
ANTI-PLANE SHEAR

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2005, 24 (S1): -4818 doi:
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[PDF 166 KB] (794)

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The spatial development of a single shear band in saturated brittle rocks for anti-plane shear deformation is investigated. The saturated rock is taken as a solid-liquid two-phase medium. Perturbation method is used to analyze the stability conditions. The solid medium is taken to be elasto-plastic，and is the function of strain，strain ratio and pore pressure or stress history. The solid medium is compressible，and the liquid satisfies the Darcy law. The inertial effects and the force between two media are considered in the analysis. It is shown that，if the angle between the proportional loading path and the direction of the localization is p/2，then the deformation is stable. This agrees well with the case of neutral loading. The case that Dq is more than p/2 corresponds to elastic unloading，while the one that Dq is less than p/2 corresponds to loading and the instability develops the fastest when Dq is equal to zero. Positive solutions for a require that the rate of pore pressure softening exceeds that of strain hardening. Under two limit conditions，namely，long wave and short wave，the saturated brittle rock is stable.

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STUDY ON RELATIVITY BETWEEN ROCK BURST AND STRESS
STATE IN DEEP TUNNEL

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2005, 24 (S1): -4822 doi:
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[PDF 180 KB] (1149)

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To study the relation between stresses and rock burst during tunnel excavation at Jinping Ⅱ hydro-power station，3D in-situ stress measurements are carried out by hydraulic fracturing and over-coring from 130 m to 3 005 m along tunnel. The measured results are as following：(1) in-situ stress at shallow depth of tunnel is controlled by dead weight topography and region formation，and a typical stress distribution of “V” shape for river valley is formed. The maximum stress is about 11.0 MPa with the direction NNW. The in-situ stress at deep depth of tunnel is high with the maximum stress about 40 MPa，and the direction is about closely vertical；(2) the direction of maximum stress changes from level state to vertical state along with increasing of level burying，indicating that dead weight stress is the dominant effect；and (3) the maximum compression stress and minimum compression stress within the tunnel cross-section are obtained by stress analysis. The possibility of rock burst is analyzed with rock burst criterion. The rock bursts are controlled by different stresses within the tunnel cross-section and restrained by ground water growth.

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REVIEW ON THE STABILITY OF ROCK SLOPES UNDER
SEISMIC LOADING

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2005, 24 (S1): -4827 doi:
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[PDF 274 KB] (2862)

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The current researches for the stability analysis of rock slopes under seismic loading are systemically discussed in domestic and abroad. The pseudostatic method，Newmark method，numerical simulation and method of comprehensive evaluation combined with post-seismic-hazards survey，theoretical and experimental research，probability analysis，reliability mathematics，engineering geology analysis，and other methods are included. Meanwhile，the application and property of those methods are summarized. The main contents，the existing problems，and the research direction are proposed to give some suggestions for the further studies.

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NUMERICAL SIMULATION OF BLASTING VIBRATION ON
HIGHWAY-SLOPE STABILITY

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2005, 24 (S1): -4837 doi:
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[PDF 236 KB] (957)

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Blasting is frequently used in cutting excavation during highway construction in mountainous area. Blasting vibration has negative effects on slopes，and the slope stability will exert great influences on the safety and economy of construction and the transportation. Therefore，a nonlinear FEM software―DYNA2D was used to simulate the effect of blasting vibration on slope stability. The laws of distribution，transmission of stress，velocity and acceleration，and displacement of observation points are analyzed，which are used to compare with the results of in-situ test. The results are as follows：(1) on the surface of the slope，the maximum velocity and displacement appeared at the bottom of the slope，but the values are permitted；(2) within the rock mass，a large tension stress area exists，but the values of stress are not large enough to break the rock mass；and (3) in practical blasting vibration construction，monitoring should be performed at the bottom and top of slopes to ensure the velocities of permitted vibration. The results show that the adopted scheme of blasting is feasible，and numerical simulation can provide important proposal for practical engineering.

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NUMERICAL SIMULATION OF PERFORATION IN PLAIN CONCRETE
PANEL WITH NOSE SHAPE OF PERFORATORS

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2005, 24 (S1): -4843 doi:
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[PDF 381 KB] (1080)

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The perforation into a plain concrete panel with ogival and flat nose perforators is numerically simulated with the BPM2D (beam-particle model in two dimensions). The varieties of velocity field in concrete and failure zone surrounding the hole are described. The BPM2D is presented on the basis of the DEM and the FEM. Three types of beam in the BPM2D have been used to form numerical model of concrete. The mechanical properties of every type beam vary with their strain-rate，and are randomly allocated according to Weibull distribution to reflect the initial heterogeneity of concrete at the mesoscale level. The effects of perforators nose shapes on the perforation are discussed with the calculated results. The destruction mode for the ogival nose perforator is a stabbing one，while that for the flat nose perforator is a plugging one. The consumed energy for perforating a uniform target with the flat nose perforator is greater than that with the ogival nose perforator，so that the residual velocity of the former is lower. The comparison of the simulated results with the experimental data shows that the BPM2D is applicable to the simulation of dynamic failure problems for brittle materials.

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STUDY ON INFLUENCE OF SPALLATION PLANES ON STRESS HISTORIES WITHIN CONCRETE STRUCTURE

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2005, 24 (S1): -4847 doi:
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[PDF 200 KB] (742)

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In order to design effectively on spallation-resistance for underground concrete structures，stress histories within concrete structures must be determined correctly. Considering the influence of spallation planes on stress wave propagation，formulas of stress histories within concrete structures are presented on the basis of one-dimensional stress wave propagation theorem. The numerical example shows that the stress histories within concrete agree well with reality by using the proposed methods，compared with methods which do not consider the influence of spallation planes. This can provide a more common method to analyze and evaluate the local response of concrete structures under blast loads.

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CHARACTERISTIC ANALYSIS OF TIME SIGNALS FOR SEVERAL TYPICAL SURFACE WAVES

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2005, 24 (S1): -4854 doi:
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[PDF 297 KB] (1390)

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Surface wave technique is applied extensively in engineering geological exploration and engineering testing. Existing theoretic studies have been focused on computation and forward and backward analysis，while engineering applications have been focused on geological exploration，roadbed compaction degree and groundwork bearing force testing. It is found that strong relativity exists between surface wave time domain signal and testing section¢s geological condition by means of studying on characteristic analysis of surface wave time signal. In media of isolated stone and hole，surface wave time domain signals occur distinct reflection and scatter. In the earth¢s surface with high stiffness，surface wave time domain signals exist higher mode component. In the earth¢s surface with weak layer，surface wave time domain signals behave lots of vibration mode component，and exist higher mode. When the earth¢s surface exists soft and stiff area，axis of in-phase of surface wave time domain signals has obvious transition，which makes location of soft and stiff area certain. Disturbing signals often exist in data collection，it determines type of disturbing signals(fixuping disturbing signals and random disturbing signals)，and eliminates their impact. It explains the surface wave time domain signals at the aspect of engineering geology by means of testing section¢s geological condition，and draws some conclusions on geological characteristic reflected by several typical surface wave time domain signals，which helps engineers for quickly judgement in field.

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EXPERIMENTAL STUDY ON MECHANICAL CHARACTERISTIC OF
LARGE-SCALE ROCK UNDER UNIAXIAL CYCLING LOADING

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2005, 24 (S1): -4860 doi:
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[PDF 213 KB] (839)

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Mechanical experiments on large-scale rock samples(length ×height ×width：1 000 mm × 1 000 mm × 600 mm) under uniaxial cycling loading are conducted and studied. The experimental results are as follows：(1) like the acoustic emission characteristic，the rules of both stress-strain curves and crack development are closely related to the largest loading that rock experiences previously，and only when the loading reaches to the peak value can the previously formed cracks develop. The fact shows the stress gradients are steep in the rock sample；(2) the stress-strain curves of the large-scale rock specimens under cycling loading are basically the same as those of the standard rock specimen；(3) the observed strain is 100 times larger than the point strain under the same observed stress. It shows rock is a kind of material with microcosmic characteristics (microcosmic heterogeneousness). The macroscopical mechanical behaviors of rock are the comprehensive results of interaction and magnification among microcosmic characteristics；and (4) it has a nearly linear relationship between the average axial point strain and the observed stress. The slope of the relationship curve in each cycle is nearly parallel. The average transverse point strain and its dispersion coefficient increase as the cycling number increases. It shows rock cracks mainly develop paralleling loading orientation under uniaxial compression. This process is irreversible accompanied by energy dissipation.

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STUDY ON DISTRIBUTION LAWS OF LANDSLIDE-THRUST IN DOUBLE-ROW EMBEDDED ANTI-SLIDE PILES

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2005, 24 (S1): -4867 doi:
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[PDF 216 KB] (1419)

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The technique of double-row anti-slide piles has been applied in landslide control works nowadays. In practical engineering，some hypotheses are adopted for design. However，the thrust-distribution in double-row piles needs more attention and urgent studies. The structural and mechanical properties of double-row piles are studied. The double-row piles structure can be regarded as rigid frame bearing horizontal pressure. This calculation model takes the back soil of back pile as the research object. The Force method of structural mechanics is employed to calculate the rigid frame. By mechanical analysis，the relevant formula is deduced. Two types of slide thrust have been discussed respectively. A case study in Hongshibao Landslide which lies in the Badong area in the Three Gorges Reservoir is presented finally，the result of which is in agreement with theory analysis.

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CONSTRUCTION TECHNIQUES RESEARCH ON ROCK
DITCHING FOUNDATION

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2005, 24 (S1): -4872 doi:
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[PDF 295 KB] (1062)

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Ditching blasting differs from common bench blasting，but it has its specialty and complexity. While in the course of blasting design and construction，the rock geology characteristic and the environment should be sufficiently realized，and the scheme of blasting and valid protection measure should be established. According to the characteristic of Zhangfang emergency water engineering of Beijing，this paper introduces the principle of ditching blasting and the scheme of blasting construction. Relative technique measures of ditching controlling blasting are put forward，such as the pattern of hole disposal，structure of stage charge，techniques of millisecond blasting，measures of reducing vibration and controlling blasting flying rock. The methods above are used in practice engineering and ideal achievement is obtained.

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RELIABILITY STUDY ON EARTH SLOPES UNDER EARTHQUAKE

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2005, 24 (S1): -4877 doi:
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[PDF 177 KB] (1126)

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Horizontal earthquake acceleration is used for the analysis of earth slope reliability. For the slope slices，force equilibrium equations are developed and the formulas of the earth slope safety factor are derived and the reliability is then studied. In the case of a slope in Shijiazhuang area，calculation results show that the safety factor with the stochastic earthquake has close relation with the earthquake acceleration and the soil property. It is clear that the influence of the earthquake is notable.

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FORECAST OF ROCK BURST BASED ON PATTERN RECOGNITION BY
LEAST SQUARE SUPPORT VECTOR MACHINE

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2005, 24 (S1): -4881 doi:
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[PDF 196 KB] (912)

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The rock burst is affected by many complex factors，so the forecast of the degree of the rock burst is a nonlinear，high dimensional，multiclass pattern recognition with small samples. Based on statistical learning theory and complying with the minimization of structure risk，a new machine learning tool—support vector machine，which can solve the problems for multidimensional functions and has good extrapolating ability at small samples occasions，and that fetches up the ANN¢s insufficiencies，is employed. In order to improve the training velocity and prediction accuracy，this paper presents a new method for forecasting rock burst based on least square support vector machine，and constructs the prediction model. The rock burst¢s influence factors are mining depth，having or no pillar coal，rock character of top plate，intricacy degree of architectonic state，coal seam pitch，thickness of coal seam，mining system，workface by blasting or vertical exploitation. The complicated nonlinear relationship between the degree of rock burst and its affected factors is presented. The application to the practical engineering shows that the method is feasible and precise.

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STUDY ON CHEMICAL EXPLOSION RESISTING PERFORMANCE OF TWO-WAY RC SLAB REINFORCED WITH GFRP RIBBON EXTERNALLY

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2005, 24 (S1): -4887 doi:
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[PDF 306 KB] (1033)

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The glass fiber reinforced(GFRP) plastic material has many characteristics such as high intensity，large ductility，resisting erosion，simple construct technology，etc.. In order to improve bearing capacity of structure and extend the expiration date，the GFRP is used to rebuild and reinforce common civil building structures. In the same time，the domestic and overseas scholars pay more attention to the characteristics about the complex structure of GFRP and reinforced concrete under static loading gradually，and have obtained many achievements. The application of complex structure characteristics of GFRP and concrete under dynamic loading is initiated. In order to study the strengthening effect and mechanism of GFRP on RC (reinforced concrete)structures under explosion load，the explosion resisting performance of RC slabs reinforced with GFRP ribbon and that the common RC slabs are simultaneously studied. The deforming processes of GFRP reinforced concrete slabs and those of the common concrete slabs under explosion loading are also studied. The test results indicate that GFRP can control the development of concrete flaw effectively and enhance the explosion resisting performance of RC slab，which can provide reference to reinforcement mechanism study of GFRP and explosion resisting design of RC slabs reinforced with GFRP.

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STABILITY ANALYSIS OF ROCK AROUND TUNNEL-TYPE ANCHORAGE OF SIDUHE SUSPENSION BRIDGE BASED ON ABAQUS SOFTWARE

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2005, 24 (S1): -4894 doi:
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[PDF 262 KB] (1269)

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Tunnel-type anchorage is not widely used in practice，and not enough attentions have been paid to its stability up to now. Based on the user-defined material subroutine interface provided by ABAQUS，a new model by combining Rankine and Mohr-Coulomb criteria is established，and corresponding interface program is developed，in which Fortran language is adopted. Based on this model，a three-dimensional elasto plastic finite element analysis on the tunnel-type anchorage of Siduhe suspension bridge is performed. The initial geostress field is calculated，and the construction process of the tunnel-type anchorage and road tunnel with New Austrian tunneling method is simulated. At the same time，the weak terrane around the tunnel-type anchorage appeared in the excavation is considered. The stability and safety factor of the rock around the tunnel-type anchorage are main contents. The results conform to those from FLAC3D analysis provided by Yangtze River Scientific Research Institute，which shows the feasibility and validity of the interface subroutine. The results can provide a reference to the current design rule of tunnel-type anchorage.
Key words：tunneling engineering；finite element；UMAT subroutine；Rankine criterion；Mohr-Coulomb model；tunnel-type anchorage；elastoplastic analysis；stability

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ANALYSIS OF AFFECTING FACTORS AND FAILURE MECHANISM
OF CONCRETE LINING UNDER EXPLOSION LOADING

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2005, 24 (S1): -4900 doi:
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[PDF 405 KB] (1017)

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The dynamic finite element method is employed to analyze the failure mechanism of vaulted tunnel concrete lining and the factors influencing failure range under the impact of explosion. The result indicates that the failure mode of concrete lining is made up of flexure，stress-shear，and cracking into layers under the condition of the explosive closing to concrete lining. With the increase of the distance between the explosive and the lining，the failure range increases firstly. Then，it declines and the failure modes is converted gradually from stress-shear to flexure. The increase of reinforcement ratio can enhance the ability of tunnel resisting failure. As the ratio of thickness to height of cross-section increases，the failure range decreases and the failure mode has the tendency of shearing failure.

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CONNECTIVITY RESEARCH OF DISCONTINUITIES AND APPLICATION IN JOINTED ROCK MASS

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2005, 24 (S1): -4905 doi:
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[PDF 248 KB] (1002)

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Through the two aspects of geometry and mechanics，stability of rock mass is influenced by discontinuities. Therefore，connectivity research of discontinuities in jointed rock mass is analyzed at two aspects：(1) geometrical connectivity reflecting hydromechanics of rock mass and spatial orientation effect of discontinuities；and (2) mechanical connectivity reflecting strength of rock mass；thereby engineering properties of discontinuities are more disclosed generally. In the paper，discontinuities in the jointed rock mass are measured by means of surveying line sampling method，and orientation and trace length of discontinuities are corrected and Mote-Carlo simulated，thus the discontinuities' network models are formed. Then the network models are analyzed and calculated，therefore geometrical connectivity is acquired；and prevailing discontinuities are found through discontinuity network model. Based on the prevailing discontinuities，a method is presented to perform persistence analysis by coupling these prevailing discontinuities with other random discontinuities. And according to the rock-bridge failure theory，shear paths with minimum shearing force are searched by using dynamic programming，then reasonable mechanical persistence ratio of discontinuities，which is more conformed to the engineering practice，can be achieved based on this method.

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DISCONTINUOUS BIFURCATION CONDITION AND ITS APPLICATION
TO SLOPE STABILITY ANALYSIS

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2005, 24 (S1): -4912 doi:
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[PDF 433 KB] (920)

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Based on Drucker-Prager yield criterion，analytical solution of discontinuous bifurcation of materials is formulated under plane strain condition，and the bifurcation condition is implemented in the self-developed elasto-viscoplastic adaptive finite element analysis software AFEAS. Elasto-viscoplastic constitutive relation and solution program of localization are given to trace inception and progression of localization zone of rock mass. Slope stability plays critical roles in many projects，studying failure mechanism of slopes has important significance of theory and application. According to Bifurcation theory，slope instability is studied as a bifurcation phenomenon. Compared with traditional yield damage theory，bifurcation theory has more advantages—process of inception and progression of localization zone can be traced，the collapse load-carrying capacity of the slope can be determined and more definite failure zone can be provided for slope stabilization. A numerical example of slope instability is studied and shows the rationality of the theory and software.

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PROPERTIES OF WAVE PROPAGATION IN POLYPHASE
SOIL-STONE COMPOSITE MEDIUM

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2005, 24 (S1): -4917 doi:
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[PDF 202 KB] (1056)

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Based on macroscopic equivalent model theories and the microscopic analytical theories，the properties of wave propagation in the polyphase soil-stone mediums are studied. The effective bulk modulus and effective shear modulus of the polyphase soil-stone mediums are derived by using the equivalent fluid model，particulate contact theory，and Gassmann¢s equations. Then，the theoretical calculation formulae of wave velocity are proposed by assuming that the polyphase soil-stone medium is made of a homogeneous，isotropic，and linearly elastic material containing polyphase soil-stone composite medium. The theoretical calculating results show that the wave velocity has close relation with dry density，soil-stone ratio，water content，depth，saturation degree，and grain diameter of polyphase soil-stone medium.

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RESEARCH ON FORECASTING OF ROCK SLOPE STABILITY
BASED ON IEA-PNN

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2005, 24 (S1): -4924 doi:
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[PDF 235 KB] (973)

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Probabilistic neural network (PNN) model is a kind of artificial neural network，which is simple in structure，easy for training and widely being used. The method uses Bayes classifying and decision-making theory to constitute the mathematic model of system；with Gauss function as activating one，it possesses the characteristics of strong nonlinear processing and anti-interfering ability. The theory and algorithm of PNN are expatiated，and then the application of PNN to rock slope stability forecasting is proposed. Immune evolutionary algorithm (IEA) that is an efficient random global optimization technique is used to optimize the parameter of Gauss function. The design idea and characteristics of IEA-PNN are introduced，and it is successful to apply this model to the rock slope stability forecasting. The results of case study show that the analysis results are completely consistent with the actual situation. It is shown that the IEA-PNN method is feasible in practice，it needs less learning sample，having more prediction-precision，stronger performance of dealing with non-linear dynamic data and better performance of non-linear system modeling than other artificial neural network methods and at the same time it provides a new approach for slope stability forecasting.

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STABILITY OF TUNNEL IN JOINTED ROCK MASSES DURING
EXCAVATION AND UNDER EARTHQUAKE LOAD

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2005, 24 (S1): -4929 doi:
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[PDF 322 KB] (1003)

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The mechanical properties of jointed rock masses are dominantly controlled by the joints. The joints may slip or open subjected to seismic load. When there exists a free surface，jointed rock masses will behave highly nonlinear with large deformation. Under ground excavation，the surrounding rock mass may be under stable condition in the environment of in-situ stress，but it may lose its stability when subjected to seismic load. The mechanical behaviors of the inclined jointed rock masses during excavation and under earthquake load are simulated by using discontinuous deformation analysis(DDA). Two improvements for excavation and lining are developed and implemented into the original DDA program，and the process of the tunnel excavation and earthquake response are simulated by using the advanced program. The whole failure process of the surrounding rock mass is simulated，which is of help to understand the mechanism of deformation and failure of underground excavation in jointed rock masses. These results suggest that the advanced DDA can be applied to the process simulation of the tunnel excavation and the failure process of the surrounding rock mass under earthquake load.

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STUDY ON LOAD TRANSFER AND DETERMINATION METHOD OF BEARING CAPACITY FOR ENLARGED PILE

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2005, 24 (S1): -4934 doi:
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[PDF 340 KB] (855)

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So far，the load transfer mechanism and the determination method of bearing capacity of pile are being also considered as one of the most difficult problems for pile foundation design. According to the physic mechanics parameters of soil and the static load experimental results of piles，and based on the nonlinear elastic theory，the pile bearing capacity and test results were all studied herein. The research results confirmed that the relation curves of load acted on the pile top and the ratio of point resistance to lateral friction of pile have distinct phase characters. The result agrees well with that of static load test. Those relation curves can be used to determine the ultimate bearing capacity conveniently for enlarged pile. Compared with the past used determination method of the load bearing capacity according to the load-settlement curves from static load tests，this new method has distinct advantages of more safety.

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INFLUENCE OF ORIGINAL DAMAGES IN ROCKMASS
ON BLASTING EFFECT

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2005, 24 (S1): -4941 doi:
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[PDF 252 KB] (851)

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According to the damage mechanics，the dynamic damage constitutive model of rock mass containing original damages is proposed. The formula of the average fragment size containing original damage variable after blasting is derived from the dynamic average fragmentation size formula of the fragile material given by Grady on the basis of fragmentation energy rules，fully considering the breaking action of the explosion stress wave and the motive fragment blocks extrusion and collision under the action of the detonation gas expansion and infiltration flow pressure. The experiment being made by our research group is aimed at verifying the results of the constitutive model. The results of the experiment coincide well with the calculation. The studies show that the influence of the original damages in the rock mass on blasting effect is very remarkable，and the average fragment size increase with the increasing of original damages. But the original damages can be controlled and utilized by modifying design parameters of blasting so as to improve the blasting effect. Some beneficial conclusions are summarized which are available for reference to practical projects.

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PRACTICAL METHODS OF PREDICTING THE SLOPE SEISMIC
STABILITY WITH GRAY CORRELATION METHOD

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2005, 24 (S1): -4947 doi:
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[PDF 158 KB] (946)

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The factors influencing on the slope seismic stability are not determined accurately. According to the numerical simulation of standard slope samples，the practical methods and concrete numerical simulation procedure judging the slope seismic stability are presented by using the gray correlation analysis method.

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COUPLED DYNAMICS BEHAVIOURS AND NUMERICAL SIMULATION
OF LEACHATE POLLUTION

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2005, 24 (S1): -4951 doi:
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[PDF 264 KB] (1006)

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Leachate transport in landfill is affected by complex geological environment. Based on fluid-solid coupled and solute transportation theory in porous media，multi-field mathematical model has been developed for describing leachate transportation，and the numerical model is given by applying P-R implicit finite difference method. The program is applied to simulate the concentration distribution of leachate in landfill，which has been presented under coupling multi-field effect. Numerical results show the convection effects become significant，especially as time passed. The rate of variation of concentration under stress field effect is lower than without coupling effect. The mainly reason is that a decrease of permeability leads to the mean velocity of the fluid slowed down with the skeleton deformation in porous media. Therefore，coupling the seepage field，stress field and concentration field is very important to study the seepage law of leachate transport. It will provide more reliable evidence for forecasting water quality polluted by leachate in aquifer.

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TEST FOR WAVE PARAMETERS OF ROCK MASS AND

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2005, 24 (S1): -4956 doi:
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[PDF 280 KB] (875)

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The static parameters of rock and soil mass are absolutely necessary for engineering practice. Static mechanical test is a direct approach to obtain these parameters，but it is often difficult because of its heavy equipment，long duration，and high expense. The dynamic test，based on the theory of elastic wave propagation，is much easier than the static test due to the light equipment，flexible methodology，and smaller expense. Comprehensive utilization of the static and dynamic parameters of rock and soil mass will bring engineering considerably technical and economic benefits. In order to overcome the influence of the error in the measurement of travel time of waves，the fitting analysis of seismic phase in wave velocity test is conducted in-situ，and a series of rules and criteria to revise the travel time measured on rock and soil specimens are put forward. The characteristics of static test and dynamic test and their synthetic utilization problems are also discussed.

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EXPERIMENTAL STUDY ON VIBRATING COMPACTION
PERFORMANCE OF GRAVEL SOILS

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2005, 24 (S1): -4965 doi:
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[PDF 193 KB] (1037)

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With designed surface vibrating compactor，a series of vibration compacting experiments of six kinds of gravel soils are carried out in laboratory，and a large amount of data about the vibration compaction of gravel soils under different vibration masses and different vibration frequencies as well as different action time of the vibration are obtained. Based on these data，the relationships between maximum dry density and the stimulating vibration frequency as well as vibrating force are studied. The eigenvalue of grain size distribution of gravel soils，a new index reflecting the nonuniform coefficient and curvature coefficient as well as characteristic grain size synthetically，are put forward，and the better correlations between eigenvalue of grain size distribution and maximum dry density as well as vibrating parameters are obtained. The vibrating compaction performance of gravel soils is summed up at last. All of these results have important significance both to theory study and to engineering practice.

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ULTRASONIC CT DETECTING FOR WEATHERING DEGREES OF LITHOID CULTURAL RELICS

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2005, 24 (S1): -4970 doi:
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[PDF 295 KB] (999)

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There are a lot of cultural relics which are of important historic significance and value in China. But，because of long time weathering，these cultural relics are damaged seriously. It is very necessary to assess the weathering degrees of these relics. Ultrasonic detecting is a non-destructive testing method to get the inner information of an object with high resolution，so it is an effective means to detect weathering degrees of lithoid cultural relics. The ultrasonic CT detecting method for weathering degrees of lithoid cultural relics with ultrasonic penetrating waves is discussed theoretically and methodologically，and a set of methods to detect the weathering degrees and the main mechanical parameters distribution of lithoid relics are put forward. By this method，the weathering degrees of the stone bars of Guyue bridge，which was built in Nan Song Dynasty in Yiwu City，Zhejiang Province，are detected，and satisfactory results are obtained.

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FREQUENCY TESTING METHOD FOR ELASTIC WAVE
VELOCITY OF ROCK SPECIMENS AND ITS COMPARISON WITH TIME TESTING METHOD

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2005, 24 (S1): -4977 doi:
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[PDF 241 KB] (889)

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Till now，the testing method for the elastic wave velocity of rock specimens with ultrasonic waves is basically the travel time testing method. Sometimes，owing to the limitation of specimens or testing conditions，etc.，the measurement for the exact travel time of a wave phase is very difficult. The relationship between elastic wave velocities and wave frequency features of rock specimens will be helpful to resolve this problem. This relationship is revealed，and the testing method for the elastic wave velocity of rock specimens based on the features of wave frequencies is put forward. Then the frequency method of rock specimens wave velocity testing is particularly introduced and the rock specimens¢ wave velocities are separately tested in time-domain and frequency-domain in this paper. The comparison between frequency testing results and time testing results show that the frequency testing method is feasible and practical.

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SURFACE BOREHOLES FOR DRAINAGE OF GOAF GASES AND ITS STABILITY ANALYSIS

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2005, 24 (S1): -4982 doi:
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[PDF 225 KB] (1308)

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As longwall caving technology prevails rapidly in China，gas emission from longwall faces and goaf area increases continuously. Traditional gas drainage techniques，such as drilling roof holes from tailgate or drilling inseam and cross-measure holes，sometimes can not meet the requirements of methane drainage for a modern longwall operation. The alternative method to drill gas drainage holes underground is to drill boreholes from surface to the goaf area. When a coal seam is being extracted out，the upper rock strata above the goaf will be undergoing discontinuous damage and continuous movement. During overlying rock strata being fractured，the surface gas drainage boreholes may be damaged due to ground movement. A method for the calculation of the stability of surface boreholes for drainage of gas from goaf area is introduced. An example of determination of borehole and casing diameters is given to demonstrate the application of the computational method. By using this method，the damage of surface gas drainage holes caused by induced excessive mining displacement can be effectively reduced if not being avoided. Surface borehole diameter and casing diameter as well as characteristics of filling materials can be achieved by calculating the horizontal movement and vertical stain at different depths.

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AN EXPERIMENTAL RESEARCH ON THE CORRELATION OF
ACOUSTIC PARAMETERS AND STRESS OF CONCRETE

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2005, 24 (S1): -4988 doi:
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[PDF 260 KB] (1082)

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An ultrasonic test of 48 concrete specimens under different loading conditions was completed，and the variation of ultrasonic pulse velocity，amplitude of first wave and maximal amplitude with the stress in concrete were researched. Contemporary，the Fourier transform and wavelet transform were used to deal with the ultrasonic signals，and it is the correlation of major frequency，amplitude of major frequency，spectrum area and stress of concrete that were analyzed. On these bases，the correlation of acoustic parameters and stress of concrete was proposed. The research shows that major frequency isn¢t sensitive to stress；the change of ultrasonic velocity and amplitude are insignificant；and the correlation between weighted spectral area and stress is sensitive and stable.

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ANALYSIS ON STABILITY OF LARGE SLOPE

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2005, 24 (S1): -4997 doi:
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[PDF 229 KB] (1005)

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The slope behind the powerhouse and the intake tunnel outlet of Geheyan power station is very high and large with rigid rock on the top and soft rock on the underside. There are several groups of cracks and faults，and there is a instable rock mass in the eastern and western areas，respectively. Several bends are considered for the reinforced project during construction. The deformations on the surface and in the deep are very small，which indicates the slope during the operating period is stable.

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STUDY ON MECHANISM OF ROCKBURST INDUCED BY HIGH
STRENGTH MINING WITH CONDITON OF NON-HARD ROOF

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2005, 24 (S1): -5002 doi:
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[PDF 352 KB] (965)

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As the exploit strength increasing，rock-burst may occur under the condition of non-hard roof. Aiming at mining conditions of high seam with fully mechanized sublevel caving mining and higher fully mechanized mining，based on the mechanics system of roof，coal and floor，and using the method of numerical simulation，the effects of time-space evolvement of mining pressure field on pressure，distortion，and destruct of mining space，mutual effect between far pressure and near pressure，and inducing conditions of rock-burst are discussed. Time-space evolvement law of collapse of coal seam and terranes and the mining pressure field are also presented. The mechanism of rock-burst and gas disaster induced by high strength exploit has been opened out.

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NUMERICAL SIMULATION OF UNDERGROUND
EXPLOSION IN GRANITE

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2005, 24 (S1): -5007 doi:
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[PDF 269 KB] (1163)

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The 3D numerical simulation of underground explosion is of interest for the protection of underground structures under explosion. The energy of explosion is sufficient to vaporize the medium around the work point. The expansion of the vaporized gas displaces the medium further out，causing deformation and failure. So the radiation transport and details of the very-early-time dynamics in the explosion source region are not considered in numerical calculations，and the energy source is modeled as an initially uniform spherical region of the appropriate energy content. A simple approximation is used for the vaporized gas，where the gas is assumed to consist of Fe and isentropic expansion of the gas is calculated. The suggested model is performed as a material model of LS-DYNA3D through its user-defined material function. Attenuation of radial peak stress and radial peak particle velocity of explosion in granite and the wall load function for decoupled explosive are calculated by using this material model. The numerical results are in good agreement with the experimental and numerical data achieved by other scholars.

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NUMERICAL SIMULATION OF HIGH-EXPLOSIVE EXPLOSION
WITH A BACKFILLED TUNNEL IN GRANITE

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2005, 24 (S1): -5013 doi:
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[PDF 344 KB] (1200)

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The dynamics finite element program LS-DYNA3D is employed to simulate the high-explosive explosion experiment in granite，which has a crooked tunnel that is backfilled with concrete stemming. The appropriate material models and its parameters are important in numerical simulation. Together with the results of high-explosive explosion experiments，the computational methods，physical models，constitutive models，and their parameters that used for calculation are established and validated by large numbers of numerical tests. Elastic-plastic-hydro material model is used for granite，and the JHC model is used to describe the dynamic response of concrete. The equation of state(EOS) of JWL is used to determine the pressure of detonation products of high-explosive. Free field parameters and the failure regions are calculated. The reach time of stress wave in wall rock and tunnel is analyzed and compared. The simulated results agree well with the experiments results. This work can be regarded as the basement for numerical simulation of the explosion in granite and can be used for such experimental studies.

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STUDY ON NONCLASSICAL NONLINEAR FREQUENCY
EFFECT ON MESO-SCALE IN ROCKS

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2005, 24 (S1): -5020 doi:
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[PDF 423 KB] (1037)

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By studying the meso-scale mechanism of the frequency effect of the non-classical nonlinear behavior， a non-classical nonlinear theory model with frequency effect is established. Using the quantitative method of studying the non-classical nonlinear behavior of rock given by Guyer，it is conveniently to get the distribution density of hysteretic elastic unit (HEU) in the so called Preisach-Mayergoyz(P-M) space. Then，a quantitative method is brought out to predict the non-classical nonlinear behavior of rock with frequency effect. With this，we simulated the behaviors of rocks under circle loading condition in several frequencies，i. e.，0.1，0.5，1，5，10，15 Hz，on computer：The results fit with those from experiments quite well. This research will be very important to the research of nonlinear wave in rock and other non-classical nonlinear materials.

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STUDY ON CRACK COALESCENCE PROCESS UNDER LOADING AND HYDRAULIC PRESSURES

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2005, 24 (S1): -5026 doi:
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[PDF 457 KB] (981)

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The coupling action of seepage and fracture on crack coalescence process under loading and hydraulic pressures are investigated. Numerical results demonstrate that the trend and magnitude of the permeability variations are controlled by the stress and the damage evolution developed in rocks. This includes the induced stress evolution of flow properties，and the regions of both diminished and enhanced flow depending on which the rock is in the linear-elastic，nonlinear，or post-failure portions of the stress-strain curves are presented. In elastic deformation region，rock permeability reduces when the rock compacts，and the decrease rate of the permeability starts to slow down or gradually to increase again when micro fractures begin to nucleate. Dramatic permeability increase occurs as soon as the macro-fracture forms in the rock.

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PARAMETER IDENTIFICATION PROCEDURE FOR GROUNDWATER FLOW MODEL WITH SIMULATED ANNEALING

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2005, 24 (S1): -5031 doi:
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[PDF 211 KB] (1194)

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The solution of inverse problem usually requires nonlinear optimization of an objective function describing the difference between measured and simulated data. Most optimization algorithms used for parameter estimation in groundwater hydrology are gradient-type methods that have the disadvantages of being very sensitive to the initial guesses of parameters and being prone to converge to local minima. Compared with traditional optimization algorithms，simulated annealing algorithm is recognized to have better capability to find the global optimal solution. The inverse problem of identifying aquifer parameters is treated as a combinational optimization problem. The simulated annealing is presented to identify the transmissivity and storage coefficient for a two-dimensional unsteady state groundwater flow model. The ill-posedness of the inverse problem as characterized by instability and non-uniqueness is overcome by using simulated annealing algorithm. The effectiveness and flexibility of presented inversion technique are evaluated and compared with descent search methods.

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STUDY ON MECHANICS MODEL OF THE FIRST CAVE IN MAIN ROOF FOR THE LARGE CUTTING HEIGHT FULLY MECHANIZED
MINING UNDER THE TWO HARD CONDITIONS

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2005, 24 (S1): -5037 doi:
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[PDF 193 KB] (702)

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According to the conditions of hard roof and hard coal，a mechanical model for the full-length working face is proposed，and it is considered that the main roof forms three block mutually hinged plate structure in the full-length model working face. The reasons of the stepped，staged，and migrated roof weighting to the full-length working face are presented. With the elastic plate theory，the stress distributions of plate in the various control boundaries are calculated and it is found that intensity of weighting in the middle of the working face is greater than those of head and end.

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EXPERIMENTAL STUDY ON THE TOTAL FAILURE COURSE OF SILTSAND UNDER UNLOADING CONDITION

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2005, 24 (S1): -5043 doi:
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[PDF 228 KB] (965)

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Unloading confining pressure tests are conducted at the pre-peak and post-peak of siltsand specimens with fixed displacement after conventional triaxial compression. In this course，testing machine does not do any works for specimens. The failures are caused by deformation energy of themselves. Based on the complete procedure of unloading confining pressure，the failure features，deformation and strength of siltsand specimens are analyzed. The test results show that unloading fracture mode is shear failure at the pre-peak and tensile-shear failure at the post-peak. Failure is easier to happen suddenly in the process of unloading confining pressure at the pre-peak than that at the post-peak. All specimens show strong dilatancy. In addition，the axial supporting capacity is very sensitive to the change of confining pressure. This is the result of the mosaic community between fractured rock blocks and reflects the structure effect along friction-sliding surface.

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INFLUENCE OF FREEZING AND THAWING CYCLE ON MECHANICAL PROPERTIES OF CONCRETE

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2005, 24 (S1): -5048 doi:
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[PDF 651 KB] (1791)

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The common concrete and the concrete dipped in 3.5% sodium chloride solution imitating seawater are subjected to freezing and thawing tests of 0，25，50，75 and 100 times，respectively. The effects of the freezing and thawing cycles on compressive strength，module of elasticity and stress-strain relation of concrete are investigated and the relevant simple formulae are established. A research on microstructure of concrete under various freezing and thawing cycles proved that with the increase of cycles，there will be more cracks in cement slurry，and concretes of various water ratios are affected differently by freezing and thawing cycles.

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3D MODELING OF LONGITUDINAL SHEAR TRANSFERENCE
OF TUNNEL IN SOFT GROUND

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2005, 24 (S1): -5054 doi:
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[PDF 274 KB] (894)

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With regard to the two typical states of loading and unloading actions of tunnel encountered in soft ground during construction and service stages，three-dimensional numerical method is applied to analyze the longitudinal shear transference of segment tunnel lining. The influence of the two types of actions on internal forces of tunnel cross-section and their characteristics are presented，which verify that the longitudinal shear transference is closely correlated with the key factor of influencing on the internal forces of tunnel cross-section caused by longitudinal loading and unloading action on the tunnel. It is concluded that the longitudinal shear transference restrains the unequal deformation of tunnel cross-section，and leads to more bearing load on tunnel lining and less bearing load on ground in the meanwhile. The additional internal forces of tunnel cross-section caused by longitudinal actions vary linearly with longitudinal shear transference and its superposition forms with significant original forces variation along the longitudinal axis of tunnel. The positive superposition occurs at the passive deformation part and is the critical control state of design. These results are obtained for the first time and will be benefit to the cross-section design of tunnel in soft soil while considering the effect of unequal longitudinal load and settlement.

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ANALYSIS OF SEISMIC RESPONSE OF PILE-SUPPORTED
STRUCTURES CONSIDERING PILE-SOIL INTERACTION

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2005, 24 (S1): -5060 doi:
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[PDF 330 KB] (1446)

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A computational model for pile-supported structures，which can duly consider the pile-soil interaction effect，is established by use of the finite element method，and its numerical implementation is made in time domain，accordingly. For the convenience of comparative analysis，the substructure method for seismic response analysis of pile-soil-structure system is briefly presented. Then a comparative study is performed for an engineering example and it is shown that the results obtained by the finite element method is common with the computational results achieved by the substructure method. These numerical results and findings will offer instructive guideline for earthquake-resistant analysis and engineering design of the pile-supported structures in practice.

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EXPERIMENTAL STUDY ON MECHANICAL BEHAVIORS OF SATURATED ROCK UNDER DIFFERENT LOADING PATHS

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2005, 24 (S1): -5065 doi:
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[PDF 269 KB] (1034)

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The different loading paths have influences on strength characteristics，deformation behaviors，and the types of rock failure. The characteristics of strength，deformation and failure of saturated rock are investigated by the conventional triaxial test and that under cyclic loading with different deviatoric stress states，for instances，current triaxial test，current triaxial test of undrainage，proportional loading test，lateral unloading test，injection test under different deviatoric stress states，unloading test of water pressure under different deviatoric stress states，and current loading test with cyclic loading，etc.. The experimental results show that the fundamental properties，i.e.，the strength decrease，deformation increase，and splitting effect of water pressure and etc.，come from cyclic loading，injecting under different deviatoric stress states，unloading of water pressure with undrainage under different deviatoric stress states，proportional loading and the lateral unloading and the like. These fundamental behaviors are very important for geotechnical engineering.

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ANALYSIS OF MECHANICAL BEHAVIOURS AND EFFECTS
OF PRESTRESSED ANCHORAGE

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2005, 24 (S1): -5072 doi:
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[PDF 182 KB] (1285)

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Prestressed anchorage technique is an important method to reinforce high rock slope. Based on the numerical simulation analysis by using 3D finite element method，not only the mechanical characteristics of tendon force，shear stress and displacement among anchor cables and grouted body and rock mass but also the anchorage effectiveness are studied. In addition，the regularity of cables pitch is discussed. It is concluded that the structural properties of rock mass is the main factor affecting anchorage stress distribution. The suggested method could be widely used for practical engineering.

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UPPER BOUND PROCEDURE OF LIMIT ANALYSIS FOR STABILITY OF SOIL SLOPE REINFORCED BY UNIFORMLY-DISTRIBUTED GEOGRID

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2005, 24 (S1): -5076 doi:
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[PDF 244 KB] (902)

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Based on fundamental theory of limit analysis of plasticity，the upper bound procedure is employed in limit analyzing the stability of soil slope reinforced by uniformly distributed geogrid. It obtains expression of the upper bound of critical height and stability number for reinforced soil slope，which are compared with non- reinforced soil slope. Eventually，the effects of slope angle，surface inclination angle，frictional angle of soil and geogrid tensile strength on stability number are analyzed for retaining soil slope.

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APPLICATION STUDY ON NONDESTRUCTIVE DETECTION METHOD OF ELECTROMAGNETIC WAVE IN ROAD TUNNEL LINING
QUALITY DETECTION

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2005, 24 (S1): -5081 doi:
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[PDF 407 KB] (1182)

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Combining with practical situation of ground penetrating radar (GPR) application in tunnel lining detection practice，the principle of electromagnetic wave of nondestructive detection technology is presented，and then the detection methods are introduced. Detection results and characteristics of wave figure which covers lining thickness，lining defect，and bar distributing situation are shown. Feedback suggestions of construction as well as problems encountered in practice when adopting GPR to detect tunnel lining quality are given. Finally，related conclusions and suggestions are proposed.

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A STUDY ON CALCULATION METHOD OF PENETRATION THEORY FOR CONFORMING SAND LAYER

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2005, 24 (S1): -5086 doi:
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[PDF 164 KB] (1165)

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The present theory formula for calculating the diffusive area of serum mainly covers spherical diffusive formula and cylindrical diffusive formula. In these theory formulas，the change of serum¢s viscosity in the process of injecting sand layer is not considered. It is well known that most of serum¢s viscosities varies with time. The theory formula for calculating the diffusive area of serum is deduced and obtained. The theory formula considers the change of serum¢s viscosity for the process of injecting sand layer. Thus，the calculation errors are removed that exist in present calculation，which are caused by assuming that the viscosity is unchangeable. The results that are achieved from the theory formula match well with that of field test. The conforming sand layer widely exist in nature，and it has good geometrical property. According to the property of conforming sand layer，the theory formula for conforming sand layer is simplified and the methods of achieving the function between serum¢s viscosity and time are presented. The method can avoid the unfavorable matter that the serum¢s viscosity must be measured in each construction. Therefore，the costs for engineering can be considerably saved.

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SPECTRUM ANALYSIS OF ELECTROMAGNETIC RADIATION FOR CREEP TEST OF ROCK WITH DIFFERENT WATER CONTENTS

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2005, 24 (S1): -5090 doi:
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[PDF 198 KB] (1018)

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On the basis of studying the relation of the load applied on the rocks with different water contents and electromagnetic radiation spectrum，and the relation of the rock electromagnetic radiation effect and regularity during the procedures from the beginning of rock creep distortion to failure，the electromagnetic radiation message characteristics of rock creep break are obtained. The monitoring electromagnetic radiation strength by test system is performed，which includes servo-added load system，receiving antenna and sonic emission sensor，A-ER acousto-electric data collecting systems，and shied system and etc.. The relations between the load applied on the rock with different water contents and electromagnetic radiation strength，and the curves of electromagnetic radiation strength with time of electromagnetic radiation strength spectrum curves，are obtained. Thus，the relationship of different water contents and different stress levels of the electromagnetic radiation spectrum are achieved. The study shows that，with different stresses，the frequency domains of electromagnetic radiation are clear with the main range of 0.0 - 0.2 kHz，and the frequency electromagnetic radiations of rock dry- nature-saturation are exhibited from low to high. Different water contents have different effects on the physical mechanical quality of rock，and the water on the rock surface can lower the total energy with rock strength and deteriorated elastic modulus，which drive the electromagnetic radiation low. Thereafter，the method discussed is useful to predict the stability of rock mass and it proves to be feasible to forecast the rock dynamic disasters.

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NUMERICAL SIMULATION OF STRATUM COLLAPSE AND GAS PERMEABILITY EVOLUTION FOR THE PROTECTED COALSEAM INDUCED BY EXCAVATION

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2005, 24 (S1): -5096 doi:
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[PDF 679 KB] (888)

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With the full consideration of the heterogeneity，existing joints，and cracks in the rock，a numerical approach of rock failure process analysis(RFPA) to simulate the stratum movement，layer separation，the whole collapse progresses，and gas permeability changing of the protected coalseam induced by deeper excavation is proposed. The numerical simulation results well displayed the whole processes of the growth of the joint，crack of the stratum and the bending，displacement，and the change of gas permeability for the protected coalseam during the deeper coalseam excavation. It also disclosed the three phases of the stratum movement，i.e.，collapse area，rupture area，and whole sunk area. It can be seen from the distribution of acoustic emission in the space that the stratum failure is transferred from deeper to surface. By the analysis of the stress fields changing，the reasons of the gas permeability improvement of the protected coalseam are presented.

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NUMERICAL SIMULATION ON GROWTH OF INCLINED CRACK
AND MIXED STRESS EFFECT FOR BRITTLE MATERIALS

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2005, 24 (S1): -5103 doi:
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[PDF 592 KB] (1217)

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The effects of mixed stress on glass specimen with an inclined straight-through crack were investigated by means of FEM and failure simulation. The simulation results of crack initiation and fractures for various inclined cracks and the figures of calculated KIC，KIIC corresponding to different crack angles in glass samples were obtained. It demonstrated that three types of stresses existed in the crack's tip：mode I stress intensity factor，mode II stress intensity factor，and the stress parallel to the crack. It was disclosed that，for brittle materials in plane stress state，mode II stress intensity and parallel stress have a considerable influence on the crack growth. Mode I stress intensity is the dominating factor，and mode II stress intensity is subordinate but the tensile stress parallel to the crack plays a role in the crack arrest. This result is different from the traditional concept that the fracture of the brittle materials like glasses and ceramics is determined by mode I stress intensity alone.

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MESH EFFECTS ON FAILURE PROCESSES OF
HETEROGENEOUS ROCKS

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2005, 24 (S1): -5108 doi:
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[PDF 458 KB] (1034)

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The purpose of this paper is to study the mesh size sensitivity in rock progressive failure process by taking heterogeneity into consideration. The size of crack tip in the plastic zone is obtained by using classical elasto-plastic theory. Then two numerical models containing a pre-existing crack are conducted to uniaxial compressive loading to investigate the homogeneity effects. Two numerical specimens are divided into the same grid meshes and they have same geometry and size but different heterogeneity. In the other way，four numerical models with the same geometry and size are divided into different meshes to study the mesh sensitivity. Numerical analysis results show that the peak strength of the rock specimens increases as homogeneity increases and crack propagates smoothly until brittle fracture takes place. It also approves that the mesh size should be small enough to fit the need of failure process analysis if the heterogeneities are taken into account in rocks. Mesh size has great dependence on the structural property in homogeneous materials，while mesh size depends on the degree of heterogeneity of the material as well as structural property in heterogeneous materials. Mesh geometry and mesh size adjustment during crack propagation process should be based on the assumption that materials are homogenous.

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WAVELET ANALYSIS OF EH–4 SIGNALS IN EXPLORATION OF GEOTECHNICAL ENGINEERING

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2005, 24 (S1): -5113 doi:
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[PDF 298 KB] (722)

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EH–4 is the update numeral instrument of continuous conductivity imaging system with electromagnetic method. The numeral signals transferred by EH–4 must be transformed into frequency ones. Fourier transform is a kind of full analysis in frequency domain without any analysis function of time domain，and fails to consider the problems of unstable signals caused by noises. It is necessary to cull the noises. The original method culling noises is surveying and its mathematical expectation is used. Its drawback is obvious，that is ，all the signals are not examined and therefore some unstable morbid signals are joined into the statistical analysis. The wavelet analysis method means analyzing each signal segment using wavelet function in different scales，and culling or revising unstable morbid signals. This method has full analysis function in both frequency domain and time domain. Through the study of discrete-time orthogonal wavelet decomposition，the signals observed by EH–4 are decomposed into different scale elements and analyzed in both time domain and frequency domain；subsequently the stability and quality of signals are ascertained in different scales. The study shows that the wavelet analysis method can analyze signals in different scales，detect unstable morbid signals and revise or cull them. It is one of effective means to analyze and detect signals in different frequency scales，and is useful to interpret signals all-round and accurately.

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CONDITION OF STABILITY OF EXPLICIT FINITE ELEMENT STEP INTEGRAL PATTERN FOR WAVE MOTION

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2005, 24 (S1): -5120 doi:
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[PDF 176 KB] (977)

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The stability of two explicit finite step integral patterns are analyzed in this paper. By use of the concept that the maximum frequency of element is the supper limit of the characteristic one of system，and combining the modal analysis method，the condition of stability is obtained. At the same time，the condition is testified by the numerical calculation .

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RESPONSE OF SHANGHAI RUNNING-METRO LINE 2 TO THE CONSTRUCTION OF ADJACENT TUNNELS

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2005, 24 (S1): -5125 doi:
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[PDF 245 KB] (1092)

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Shield-driven tunnels of the Pearl Line 2 were constructed adjacent to the Metro Line 2 tunnels near Dongfang Road Station in Shanghai. A minimum distance of 12.3 m between the centerlines separates the new and existing tunnels from each other. In view of the scale and distance of construction，significant influence on Metro Line 2 tunnels is expected. The paper presents the monitoring of the tunnel deformations during the process of construction. Automatic monitoring system of electric level bar was installed in the Metro Line 2 tunnel to monitor their displacements and to ensure the safety of running Metro Line 2. It describes the characteristics of influence from the thrust of a succeeding tunnel to a preceding tunnel and gives some advices about the planning and construction of the tunnel adjacent to the existing tunnels. FEM analysis is applied to provide comparison with the measured data.

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STUDY ON THE FROST HEAVING OF CANAL LINING BLOCKS

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2005, 24 (S1): -5130 doi:
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[PDF 247 KB] (968)

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The mechanism of frost heaving of canal lining blocks is studied and the methods of calculating frost heaving and freezing of canal are discussed. On the basis of the works，a means of combination with cutting and resistance is proposed to deal with the frost heaving. The suitable tab of concrete in canal blocks and corresponding thickness and size in different position of cross section are calculated to obtain a optimum section of canal lining blocks with frost heaving，and some detailed measures are put forward to solve the problem of frost heaving in canals. This research was applied to devise the main canal and branch canal in Shibaochuan Reservoir and a good effect was realized. It not only solves the problem of frost heaving of canal but also declares the maintenance cost，improves the efficiency of routing，and saves water resources.

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NUMERICAL STUDY ON SHEAR FAILURE OF JOINTED ROCK WITH SEVERAL FLAWS UNDER SHEAR TESTING

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2005, 24 (S1): -5136 doi:
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[PDF 479 KB] (965)

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The failure of jointed rock under shear loading is commonly demonstrated as propagation and coalescence between neighboring fractures，therefore，it is of great importance for engineering design to study shear strength and failure pattern of jointed rock with several pre-existing joints. Rock Failure Process Analysis code (RFPA2D) is employed to simulate the failure process of rock specimen with several discontinuous flaws under shear testing. The influence of flaws’ geometrical characteristic on failure pattern and shear strength is discussed. The results demonstrate that the failure patterns are mainly controlled by the flaws’ geometrical characteristics. Due to the heterogeneity，rock failure mainly results from tensile damage but shear damage still exists，which has influence on the shear strength.

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SUPPORT AND REINFORCEMENT TECHNIQUE FOR THE PROTECTED IRREGULAR PILLAR AND REMAINED GATEWAY ALONG FULLY MECHANIZED TOP CAVING MINING FACE

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2005, 24 (S1): -5141 doi:
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[PDF 379 KB] (911)

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Based on the analysis of the pressure characteristics of the remained roadway along goaf，a comprehensive support system is designed and the reasonable parameters of the support system are determined by numerical simulation and analysis of rock broken zone. The supporting mechanism for different width of pillar protection is clarified. The control technique is proposed and employed through reinforcing irregular pillar in its two sides，installing a row of hydraulic prop and anchoring of roof strata which hangs the mesh and bolt rock mass as an auxiliary means to support the gateway. The reinforcing system forms a set of control system，which acts at the key position and in key period in clear mechanism to the mining influenced gateway. The site measurement shows good results of the support.

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APPLICATION OF ANSYS IN FORECASTING OF WATER INJECTION WELL CASING DAMAGE

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2005, 24 (S1): -5146 doi:
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[PDF 218 KB] (1188)

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Casing damage during water injection well blowout is general in petroleum engineering，and it is difficult to resolve in many oil fields of China. In order to study the mechanism of the problem，fluid-solid coupled model is set up. According to the fundamental equations and boundary conditions，the ANSYS function of temperature field analysis is similar to that of seepage flow field. Based on the similarity of the formulas between the temperature field and fluid field，the coupling element between temperature and stress—Solid 5 Module in ANSYS program is employed to analyze the fluid and pressure coupling in the strata-casing-cement system. The method can solve the seepage flow problem of complex boundaries and mediums. By means of numerical simulation，the fluid field in the strata and the relation between casing extrusion stress and pressure releasing rate are studied. The simulation results show that，the bigger permeability，the bigger extrusion pressure of casing damage as the same relief discharge.

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NUMERICAL RESEARCH ON FRACTURE SATURATION FOR
LAYERED ROCK STRATUM

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2005, 24 (S1): -5151 doi:
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[PDF 1153 KB] (998)

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Fracture saturation is a common phenomenon in geosciences. Based on the FEM code，the mechanisms of fracture saturation and the factors influencing the spacing of the fracture are analyzed. The results show that the stress state between the adjacent fractures changes from tension to compression as the ratio of fracture spacing to layer thickness decreases. This stress state transition precludes further infilling of fractures，which results in the fracture saturation. The process of the fracture saturation is vividly represented. And from results of the numerical simulation，the rules of initiation and propagation of the fractures is recognized.

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STUDY ON FORECASTING MATHEMATICAL MODEL OF SAFETY ROOF THICKNESS OF UNDERWATER TUNNEL

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2005, 24 (S1): -5157 doi:
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[PDF 225 KB] (785)

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Aiming at the normal and safe work of Songhua river tunnel in Harbin which will be built recently，and using optimum analysis of a factorial experiment，the FEM models which approximating the actual problems on 54 different cases assumed are established and repetitive calculations are carried out to research the relations between various factors and the safety roof thickness of tunnel and to screen out the main affecting factors of safety roof thickness of tunnel；Considering soil-liner interaction，the soil and liner are assumed to be homogeneous，elastic-plastic，continuous，isotropy medium. It is found that the main affecting factors consist of hole diameter，altitude of water，elastic modulus of soil，unit weight of soil，Poisson’s ratio of soil，cohesion of soil，angle of internal friction of soil，elastic modulus of liner，thickness of liner. And then，a stepwise regression analysis method is adopted to obtain the forecasting mathematical model on the safety roof thickness of tunnel which is capable of synthetically embodying the combination action of all main affecting factors. The model’s reliability and efficiency are verified by a calculation example of underwater tunnel.

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NUMERICAL SIMULATION ON MINING INDUCED BED SEPARATION OF OVERLYING STRATA

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2005, 24 (S1): -5164 doi:
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It is very difficult for theoretical analysis and field observation since the movement and bed separation characteristics of overburden strata above mine voids induced by underground mining is a very complicated problem，which influenced by many factors，and the deformation and movement of overlying strata are not visible and touchable. In this paper，the movement and failure process of strata induced by underground mining are numerically simulated by using the rock failure process analysis code(RFPA2D) to investigate the height of bed separation development，the location of the bed separation zone and the effect of the extracted thickness of the coal seam on the development height of bed separation. Numerical simulations demonstrate the whole process of mining induced strata movement and the characteristics of bed separation，furthermore，the relationship between the height of bed separation and the advance distance of coalface，the effect of the extracted thickness of the coal seam on the development height of bed separation are indicated. Numerical results offer important theoretical basis and reliable evidence for the determination of the location and scale of the bed separation zone wide application of the technique of grouting into the separated strata to control the surface subsidence.

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STUDY ON THE EVALUATION MODEL OF ROCK MECHANICAL PARAMETERS WHILE DRILLING

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2005, 24 (S1): -5168 doi:
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[PDF 228 KB] (1146)

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During drilling well，keeping wellbore stability is very important for drilling normally. More and more importance is attracted to the wellbore stability evaluation while drilling，because it can reveal the wellbore status real-time. And rock mechanical parameters are essential to the wellbore stability evaluation，so developing the model of rock mechanical parameters evaluation while drilling becomes core of the work. On the basis of the mixture theory，the influence factors of rock physical properties are entirely recognized，and the important influences of microstructure on rock physical properties，especially on mechanics，acoustic velocity and resistivity property，are analyzed. Statistical analysis of field logging data is progressed，consequently a linear relationship between rock acoustic velocity and ratio of logarithmic resistivity at different detecting depth is obtained. On this basis，the model of rock mechanical parameters evaluation with LWD(logging while drilling) formation resistivity data is developed. The model is applied in evaluation of rock mechanics and wellbore stability in some areas，and it wins a good effect.

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COMPARATIVE ANALYSIS ON INFRARED TEST AND
NUMERICAL TEST FOR A HOLE-PREFORMING
SPECIMEN¢S FAILURE PROCESS

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2005, 24 (S1): -5173 doi:
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[PDF 255 KB] (814)

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The thermal infrared imager is used for testing the deformation and failure process of hole-preforming concrete specimens，and thermal infrared images which indicate temperature field changes of testing surface of specimen are obtained. Furthermore，the numerical test is conducted by using a rock failure process analysis computer program (RFPA) to simulate specimen¢s cracks expansion process as load applying. The results of numerical test and specimen¢s stress condition analysis approve that as loads applying，in some regions of specimen where close to preforming hole，the stress concentration will take place. In those tension stress concentration regions，microcracks will generate，expand and connect to form macroscpic cracks gradually，which cause the specimen failure ultimately. From thermal infrared images，the temperature of testing surface rises generally. Moreover，it is found that the rate of temperature rising is in some positive correlations with the loading speed. Comparing results of thermal infrared test and numerical test，it reveals that regions where tension stress concentrates and microcracks generates in numerical test are corresponding to regions where temperature rises rapidly. It is a powerful proof to confirm that the generation and expansion of microcracks is one of major reasons to cause the temperature change of specimen during the failure process. This result could be regarded as the failure omen information of similar concrete structure，and could be used for forecasting the failure of concrete or rock structures.

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HYPERBOLIC HYSTERESIS LOOP MODEL AND FOURIER SOLUTION OF DYNAMIC FOUNDATIONS

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2005, 24 (S1): -5178 doi:
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[PDF 206 KB] (865)

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The resistance-displacement relationship of dynamic foundation systems subjected to cyclic loading exhibits two significant characteristics—nonlinearity and hysteresis，due to soil-structure interaction effects. In this study，foundation-basement is abstracted as fixed parameter lumped parameter system for simplicity. A nonlinear dynamic model possessing viscous damping is set up with the third power polynomial function，which is used to represent the nonlinear behavior of force-displacement interacting between soil and foundation. And a new hyperbolic hysteresis loop model of dynamic foundations is presented exteriorly adopting Masing rules extend the exponential backbone curve into the loop which simulates nonlinear and hysteresis characteristics of the system. The nonlinear mathematical model developed includes the parameters such as soil stiffness，nonlinearity of passive earth pressure，displacement scale and velocity direction. It¢s difficult to solve the constitutive function intactly by using general analytical method for its complexity，so the paper makes use of Fourier progression approach in study. The paper investigates periodic solution of the dynamic system with the hyperbolic hysteresis loop model and obtains the time-history and frequency response characteristics of the foundations under harmonic excitation. The studies show that the Fourier method，which is used to analyze the systems of dynamic foundations with the hyperbolic hysteresis model，is precise and convergent，and the results of emulation agree with the specific experimental data.

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APPLICATION OF ANALOGY METHOD IN THE STUDY OF TRIAXIAL COMPRESSIVE TEST ON FROZEN SOIL AT LOW TEMPERATURES

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2005, 24 (S1): -5183 doi:
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[PDF 178 KB] (947)

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The technology and key problems of analogy method applied in the triaxial compressive test study of frozen soil are presented. Based on the theorem of Bockingham p which is widely applied at present，using the dimensional analysis method，and considering the relation of frozen soil¢s constitutive equation，water content and density，the analogical variables relations are studied and analogy relationships of shear strength indexes are obtained. Therefore，the analogical value of shear strength indexes at different test conditions can be deduced from a test result. Test results also validates that the deduced analogy relations of frozen soil shear strength indexes have good precision and can be adopted in frozen engineering and other relative study field. For the low temperature test with shortcomings of higher energy consuming，the longer time occupied，the higher money cost and the more difficulty to control test conditions，the study results presented here can reduce the same tests and have significance in practice.

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STATUS OF THE STUDY ON THE TECHNOLOGY OF CONTROLLING FRACTURE IN NEAR WELLBORE

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2005, 24 (S1): -5189 doi:
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[PDF 241 KB] (1229)

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Development of hydraulic fracturing technique is summarized. The mechanism and application of three kinds of fracturing technology are introduced，which can control the fracture rupture and extension in near wellbore. These technology include high-energy gas fracturing technology，hydrajet fracturing technology and shear fracturing technology. The high-energy gas fracturing is a new technology，which become mature gradually in stimulation at domestic oilfields. It can manufacture several fractures which are uncontrolled by in-situ stresses. The action of stimulation of high-energy gas fracturing lies in the mechanical action，pulse shock wave action，thermal effect，chemical action. The hydrajet fracturing technology is a new method that combines hydrajetting and fracturing techniques. By using this new method，operators can position a jetting tool at the exact point where the fracture is required without using sealing elements. Unlike other techniques，this new method allows operators to place multiple fractures in the same well. The mechanism of shear fracturing technology is different from the normal hydraulic fracturing. The rock of reservoir will produce shear failure and bulk seepage will appear when this method is used. Compared with area seepage，bulk seepage has more superiority. By researching the disadvantage of these technology，the developing trends and questions related with the application in oil field are put forward.

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ELEMENT MATRIX¢S PRECISE CLOSE SOLUTION OF NO THICKNESS AXIAL SYMMETRY SLIDING SURFACE BETWEEN PILE
AND SOIL CONTACT

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2005, 24 (S1): -5194 doi:
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[PDF 146 KB] (885)

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It has merits of simple，directness and concept clarity for simulation of the sliding state between pile and soil contact surface by using no thickness sliding surface element under axial load. Aiming at the axial symmetry problem of pile and soil interaction，according to basic concept of element matrix，by simplifying the thickless sliding contact surface and integral calculating to perimeter of pile，an element matrix¢s precise close solution of no thickness axial symmetry sliding surface between pile-soil contact is obtained which is fit for simulating the slide between pile and soil contact surface and to provide the theory basis for its further application. It indicates that the precise solution of element of the no thickness axial symmetry sliding surface can simulate the columnar pile and soil contact surface better，and the precise solution is easy to be adopted in the FEM numerical simulation. The surface sliding element is a special form，and it can be uniformly expressed by the axial symmetry sliding element. Consequently，it reduces the element types in the numerical simulation study of pile and soil interaction. It is significant to reduce calculating domain，work of preparing data，time of calculating and increase calculate benefit.

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STUDY ON RELIABILITY ENTROPY OF SUPPORT SYSTEM IN MINE

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2005, 24 (S1): -5198 doi:
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[PDF 228 KB] (892)

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The stability change of surrounding rock supporting system in mine is taken as an information source and the support reliability is treated as a handling process of information collection，transmission，process and feedback. By analyzing the relation between information entropy and reliability of the mineral well，and the concept of reliability entropy is obtained. Since the information entropy represent uncertainty of system or degree of disorder，the reliability entropy models of support system in mines and calculation method are set up，which express an average reliability of system. This method has been applied in practice，and a good effect is realized.

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RESEARCH ON ROCKBURST FOR HIGHLY GASSY DEEP
MINE IN FUXIN COAL MINING AREA

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2005, 24 (S1): -5202 doi:
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[PDF 178 KB] (1131)

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On the basis of particular case of rockburst in Fuxin coal mining area，the rockburst characteristics are introduced，and the mechanism and prevention of rockburst for high-gas deep mine are put forward. There are main particularities for the rockburst in Fuxin coal mining area，for example，the geological structure is complex，the depth of mining is deep，the gas content and pressure is great，and a great lot of elastic energy accumulates in the coal seam，roof or bottom. When the coal mass is in turmoil by mining activity，a great lot of elastic energy are released and rockburst occurs. After deep mining，rockburst continually occurs. This shows that deep mining is direct cause of rockburst. To avoid gas calamity of high-gas mine，the amount of gas-pumping is increased，and a great lot of gas is discharged from coal seam by desorption and seepage. Because the physical and mechanical properties of coal are changed，gas calamity turns to rockburst accident. Thus the frequency and intensity both increase obviously. Controlling the amount of gas-pumping can achieve the goal of reducing gas-burst hazard and avoiding rockburst. The means of the water injection in coal seam with rockburst tendentiousness can improve the state of coal brittleness increase due to gas-pumping，and rockburst danger may be reduced.

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INFLUENCING FACTORS AND MAGNITUDE ANALYSIS
OF FAULT ROCKBURST

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2005, 24 (S1): -5206 doi:
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[PDF 179 KB] (1060)

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The interrelated parameters of fault rockburst are analyzed according to the surrounding rock-fault model and the fold catastrophe. The magnitudes of fault rockburst are forecasted. The fault rockburst is a dynamic phenomenon due to mining activities leading to the fault dislocation abruptly and the elastic strain energy release rapidly. The more the energy releases，the higher the magnitude is，and the graver the destructiveness is. So，the prevention and cure must be emphasized to avoid personnel casualties and to decrease grave loss. Its magnitude increases with the increasing of initial shear modulus and soften index of fault，and decreases with the increasing of the fault’s thickness and initial shear modulus of surrounding rock. The results show that the analysis of fault rockburst based on fold catastrophe theory is consonant with actual case.

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NUMERICAL SIMULATION OF CONTAMINANT MIGRATION PROCESS FOR LANDFILL CONSIDERING EFFECTS OF SORPTION AND DEGRADATION

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2005, 24 (S1): -5211 doi:
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[PDF 392 KB] (938)

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The mathematical model is developed for simulating the contaminant transport process of landfill in the compacted clay liner underlying a aquifer with a finite depth，in which effects of both waste bio-degradation and nonlinear sorption as well as first-order dynamic degradation of contaminants are considered. Through numerical computations，the effects of both physico-chemical reaction due to sorption of contaminants on soil skeletons and chemical reaction caused by first-order kinetic degradation of leachats on the contaminant migration processes are studied. A comparative study is made for different combinations of various parameters. It shows that nonlinear sorption and first-order kinetic bio-degradation of contaminants play significantly important roles in the transport of pollutants. Breakthrough curve of compacted clay liners tends to display the following features，(1) the front of the curve becomes sharper and narrower；(2) peak value is forward shifted with heavily unsymmetry with respect to the mass center；and (3) tailing gets longer. The maximum sorption capacity，which is given by factors K2 in Langmuir isothermal equation of sorption and mass density of soils，is used to represent the coupling effect of nonlinear sorption. It is demonstrated that this comprehensive parameter considerably affect the contaminant transport，and the hydraulic conductivity of compacted clay liner is a key factor for the governing migration of pollutants.

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BOLTING MECHANISM OF A NEW NAIL-TYPE DUAL ANCHOR-ROOT PRESSING RING ANCHOR AND ENGINEERING APPLICATION

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2005, 24 (S1): -5217 doi:
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[PDF 177 KB] (1130)

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A new nail-type dual anchor-root pressing ring anchor is introduced and the anchorage force of the kind of anchor is provided by the dual anchor-root，i. e.，the first anchor-root controls the anchor direction，and the second anchor-root can strengthen the anchoring force when the anchor is embedded in surrounding rock mass. Meanwhile，the first anchor-root can directly anchor the rock mass when it is used in the soft rock. The anchorage length of bolt can be controlled by adjusting the distance of anchor-boot and pressing ring. The technical parameters of bolt are also presented. By the testing contrasted with cement bolt and in-situ slot-bolt，it is found that the anchorage force of the nail-type dual anchor-root pressing ring anchor is considerably high，and its credibility of anchoring force can be guaranteed. The displacement of the bolt is comparatively lower，and it can validly strengthen and prevent the deformation of surrounding rock mass. At the same time，its construction is very quick，and it can stand the exerted loading immediately. Every part of this anchor has strong function and the anchor has good adaptability. By applying this kind of anchor at San coal mine in Dayan mine co.，the supporting effect of the anchor is satisfactory.

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DESIGN AND ANALYSIS OF BELLED PIER FOUNDATION COMBINED WITH FLAT AND WIDE GRADE BEAMS

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2005, 24 (S1): -5221 doi:
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[PDF 234 KB] (970)

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By comparing the mechanical properties of pier foundation with those of normal non-reinforced spread foundation and cast-in-situ pile with hand excavation，the working mechanism，ground failure mode，and bearing capacity about pier foundation combined with flat and wide grade beams are analyzed. The influence of soil groups of sustaining layer，bottom diameter of pier foundation，relative embedment depth and soil compactness on the increase coefficients of subgrade bearing capacity in pier foundation are discussed. Then，the conclusion in which the bearing capacity of pier foundation is higher than that of cast-in-situ pile with hand excavation is achieved，and the empirical formulas for increase coefficients of subgrade bearing capacity in pier foundation and cast-in-situ pile with hand excavation are presented. It is also found that designing cast-in-situ pile with hand excavation with the smaller relative embedment depth according to the code，which is being used，will lead to a relatively larger calculation result. This will be danger in engineering application.

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SEARCHING CRITICAL FAILURE SURFACE IN SLOPE STABILITY ANALYSIS WITH GENETIC ALGORITHM

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2005, 24 (S1): -5226 doi:
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[PDF 195 KB] (1001)

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Based on genetic algorithm and Bishop¢s method，searching methods of circular sliding surface applied widely in engineering for the critical failure surface are presented and the minimal safety factor is located accordingly. The searching critical failure surface of a general soil slope is difficult as the objective function for the factor of safety is non-convex and multiple minimal exist in general，but genetic algorithm works well on optimization for multiple extremes. Traditional methods use constant upper and lower bounds of the design variables，which would enlarge searching band and create many unacceptable solutions to meet the requirements on kinematically acceptable mechanism. These solutions need be removed，which will cause efficiency loss for searching. For this problem，real-valued genetic algorithm is proposed and the constraints of the problem are transformed to the determination of the dynamic upper and lower bounds of the design variables. So，searching band is reduced and the efficiency for searching is improved. The critical failure surface can then be located with high precision with reasonable calculation time under the presented proposal. Numerical example shows that analyzing method of the slope stability based on the genetic algorithm is a global optimal procedure that can overcome the drawbacks of local optimum widely existing in classical searching methods. The analytical result is satisfactory.

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IN-SITU TEST OF BLASTING TOE-SHOOTING METHOD
APPLIED IN SOFT FOUNDATION TREATMENT

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2005, 24 (S1): -5231 doi:
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[PDF 324 KB] (984)

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The blasting toe-shooting method is a new technique for soft foundation treatment in mountainous area. Based on the theory of soil mechanics and explosive mechanics，the mechanism of blasting toe-shooting method used in mountainous area is studied，and the formulae of charge weight about relations between the parameters of charge and soft clay are presented. Furthermore，the construction techniques of blasting toe-shooting method and test means of foundation after being improved are obtained according to analysis of experience and mechanism. The achieved results show that blasting toe-shooting method can satisfy the requirements of the bearing capacity and deformation of embankment foundation in mountainous area.

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STUDY ON THE LAW OF AFFECTING DEPTH UNDER LOW-COAL DEPOSIT DURING MINING

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2005, 24 (S1): -5237 doi:
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[PDF 357 KB] (943)

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The law of bottom failure depth is the key reference to safety decision in mining above confined water. Usually，research on the failure depth of coal seam floor is performed through water injecting into cracks caused by mining，numerical simulations，and similitude material experimentation，etc.. Recently，CT and other physical methods are used to measure the integrality/damage of rock mass，even in some coal mines. Shear wave velocity is an in-situ test method and suitable for carrying out on the surface. The trial is made to gain the bottom failure depth in work face 11703 of Tianzhuang coal mine，which is beneath the coal seam No.17 with a thickness of 1.2 m in average and a distance of 20～25 m to No.14 limestone，and about 50 m away from Ordovician limestone. The test is performed before and after mining in two locations，each lying in the roadway of the workface. Accordingly，a plane of strike direction and two planes of incline direction through the testing locations are ascertained to simulate the mining process；and the distribution of tensile stress，plastic area，and variation of plastic zones are analyzed，from which the failure area of coal seam can be divided into severely destroyed area，obvious disturbance area，and affected area. Simultaneously，the distinct variance points of wave velocities recorded before and after mining are at the depth of 13.27 m and 13.63 m，respectively，with which the simulation results agree well. Then the conclusion can be made that the failure depth is shorter，about 11～12 m，in the middle of workface and longer，about 13.5 m at the edge of working face. The results show that shear wave velocity method is reliable to detect the failure zones in the bottom of coal seams in the working face 11703.

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ANALYSIS ON SLOPE STABILITY WITH FUZZY PATTERN RECOGNITION MODEL OF SUBJECTIVE AND OBJECTIVE WEIGHT DETERMINATION

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2005, 24 (S1): -5243 doi:
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[PDF 169 KB] (913)

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The analysis of slope stability is influenced by numerous factors with vagueness and randomicity. Although fuzzy comprehensive evaluation method is used to analyze slope stability，it is difficult to determine the weights of different factors appropriately，which are usually given by experts experientially. Thus，the application of the fuzzy comprehensive evaluation method is limited to certain extent. Considering the above-mentioned disadvantage，a multi-pole fuzzy pattern recognition model of subjective and objective weight determination is presented to analyze slope stability，in which the initial weights are given objectively by the alternative iteration model，and then，an appropriate adjustment may be made subjectively according to the simplified fuzzy decision method of two-element comparison. The importance of the expert and the advantage of the numerical calculation are fully considered in the model. The rationality of this method is shown by a comparative analysis of engineering case.

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NEURAL NETWORKS METHOD FOR ROCK MASS
CLASSIFICATION OF HIGHWAY TUNNEL

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2005, 24 (S1): -5248 doi:
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[PDF 202 KB] (862)

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According to classification criterion of highway tunnel，the classification indexes are comprehensively considered，and neural networks method of rock mass classification of highway tunnel is established. Proper classification indexes are chosen and standardization of indexes data are conducted by vector method，and training samples of neural networks are built. Training results of neural networks can provide the judgement basis for rock mass classification of highway tunnel. Hereby，surrounding rock mass in Hanjialing tunnel is classified. The feasibility，veracity，and advantage of founded neural networks method are verified.

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APPLICATION OF CEMENT-FLYASH-GRAVEL(CFG)PILE TO THE GROUND TREATMENT OF BOX BEAM PREFABRICATE FACTORY OF SHOUZHOU—NANTONG BRIDGE TENDER B2

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2005, 24 (S1): -5256 doi:
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[PDF 270 KB] (1112)

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The application of cement-flyash-gravel pile (CFG) pile in pre-manufacturing plant ground reinforcement in Sutong bridge is introduced，which covers the project survey，geological and the landform characteristic，the ground processing method，the ground design，the construction，and the examination and so on. According to the composite ground load experiment，the examination results，have carried on an objective evaluation to its reinforcement effects.

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STUDY ON MULTI-SIGNAL INTEGRITY TESTING
OF FOUNDATION PILES

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2005, 24 (S1): -5262 doi:
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[PDF 259 KB] (922)

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The low-strain reflected stress wave test method is widely used in detecting the structural integrity and inner quality of foundation piles. However，insufficient and incomplete data obtained in practice make it difficult to accurately detect faults and cracks in foundation piles. Innovated multi-signal piles integrity detecting system，i.e.，multiple points pulsing and multiple points receiving to process the obtained data on basis of on multiple superposition method，is proposed. It shows that the multi-signal foundation piles integrity detecting system can effectively restrain the signal interference and elevate the signal-to-noise (SNR) and testing precision of foundation piles through engineering practice，and thus it can improve the accuracy and reliability of foundation pile integrity tests. In addition，this method can also be applied to various types of structures and materials as expected.

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A SIMPLIFIED METHOD FOR THE STABILITY ANALYSIS OF SOIL- NAILED WALL

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2005, 24 (S1): -5267 doi:
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[PDF 193 KB] (893)

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Based on the in-situ tests and theoretical analysis，a simplified method，which can be used to analyze the stability of soil-nailed wall，is proposed. The simplified method assumes that the fixed circular potential failure surface passes through the toe of the wall and intersect the top at about 0.36 H，and trapeziform earth pressure along the depth of the wall. This method has the advantage of avoiding the tedious processes of trial and error to search the potential failure surface. The calculation results of two engineering projects show that the proposed method has its practical value.

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APPLICATION OF COMPREHENSIVE MEASUREMENT METHOD TO CHECK GROUTING EFFECT IN MINED-OUT REGION

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2005, 24 (S1): -5271 doi:
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[PDF 356 KB] (1138)

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The point-surface comprehensive measurement method to check the grouting effect in mined-up region under highway is presented. Through comprehensive measurement test，it indicates that the prospective grouting effects are verified. Besides the general and direct methods such as bole sampling and injection test，etc.，three-lateral resistivity logging and high-density resistivity methods are effective to check the grouting effect in saturated mined-out region. Even if the point-surface comprehensive measurement methods are adopted，the grouting effect can be evaluated accurately and fully.

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SHAPE OF PLASTIC AREAS AND FRACTURED ZONE OF SURROUNDING ROCKS OF ROADWAYS WITH WEAK LITHOLOGY STRUCTURES

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2005, 24 (S1): -5275 doi:
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[PDF 424 KB] (1056)

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According to the occurrence of the inhomogeneity and non-equilibrium for the failure deformation of roadways surrounding rocks in the coal measures strata，the concepts of weak structure and weak structure body of roadways of surrounding rocks are presented. Based on numerical simulation and in-situ observation，the distribution characters of plastic areas，in which the different types，section shapes and stress states of surrounding rocks are considered，are analyzed；and the growth characters of fractured zone of roadways with weak lithology structure are studied. The achieved results can provide references to the non-harmonious control on weak lithology structure roadways.