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2005, 24 (19): -0 doi:
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ON MECHANISM OF RIGID-BODY LIMIT EQUILIBRIUM METHOD FOR ABUTMENT STABILITY ANALYSIS OF ARCH DAM

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2005, 24 (19): -3403 doi:
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[PDF 710 KB] (993)

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Based on 3D nonlinear finite element emulation analysis of Xiluodu arch dam，the fundamental and supposition of rigid-body limit equilibrium methods are discussed. The stress distributions of the sliding surfaces of sliding blocks are computed，including the safety factor of sliding surfaces and blocks of each loading step，yield area and shearing strength of sliding surfaces during overloading. On the basis of the results，the process of sliding failure of blocks due to deformation is discussed systematically.

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STUDY ON CREEP BEHAVIOR OF ALTERNATIVELY
DISTRIBUTED SOFT AND HARD ROCK LAYERS
AND SLOPE STABILITY ANALYSIS

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2005, 24 (19): -3410 doi:
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[PDF 429 KB] (1431)

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The time-dependent behavior of rock mass is one of the important factors that influence the deformation and long-term stability of the slope. As an engineering example，Maya high slope is studied，which is located at the Shuibuya dam site on the Qingjiang River，with alternatively distributed soft and hard rock layers. The creep failure characteristics of different soft/hard rocks are studied through laboratory compressive-creep tests. Then，the rock rheological constitutive model is established；and the parameters are identified accordingly. With these understandings，the time-dependent behavior and the stability of the Maya slope are analyzed by using 3D viscoelastic-plastic numerical method. The results show that the time-dependency effect is very remarkable. As for the high rock slope with large-scale excavations，the creep characteristics influence the quantity of the displacement and change its direction. In the long-term running process of the engineering，the changes of the stress field induced by the rock creep will cause the plastic zone to extend from slope surface to the inward；and the extending range could stretch dozens of meters for ten years.

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STUDY ON DEVELOPMENT AND APPLICATION OF THREE- DIMENSIONAL INTELLIGENT INFORMATION SYSTEM FOR SLOPE SAFETY ASSESSMENT

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2005, 24 (19): -3419 doi:
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[PDF 479 KB] (1208)

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Based on the geographic information system(GIS) and intelligent analysis，the integrated study of slope safety assessment and three-dimensional information system are performed with much attentions to the common and important objects of geotechnical slope. By utilizing the development tools of Visual C++，DirectX and database platform of Access and SQL Server，an integrated analysis software system，i. e.，intelligent geotechnical engineering information analysis system (IGIAS) with independent substratum and self-copyright，is developed，which has been distributed on the internet. The IGIAS development thought，implementation methods，structure and basic functions are introduced. Finally，based on the IGIAS，a case study related to three-dimensional visualization and hazard subzone by using evolutionary artificial neural network is presented. The results indicate that the developed software has a prospective future in geotechnical engineering.

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STABILITY ANALYSIS OF SLOPES WITH STABILIZING PILES AND THEIR SIMPLIFIED DESIGN

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2005, 24 (19): -3427 doi:
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[PDF 340 KB] (986)

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Based on the kinematics approach of limit analysis and the concept of shear strength reduction，the equation for expressing the limit-equilibrium state is formulated and is employed to determine the factor of safety and its corresponding critical failure mechanism for a given slope. Through numerical analysis of typical examples and comparisons with the results computed by using both limit equilibrium method and finite element method，the reasonability and applicability of the proposed procedure are verified. Then，for the slopes whose factors of safety cannot fulfill the requirement of overall stability for the given loading condition，the stabilizing pile is considered for reinforcement of the slope. The upper-bound theorem of limit analysis is employed once again for establishing the limit-equilibrium equations of the slope reinforced by stabilizing pile in which the mobilized strength parameters are given by the actual strength parameters with a reduction by the desirable overall factor of safety. The lateral effective earth pressure acting on the pile can be chosen as the objective function；the mathematical optimization technique is utilized to define the critical state. The dimensionless critical overall lateral effective earth pressure is used in the structural simplified design of pile. Finally，the principle of maximum and minimum values is employed to optimize the most rational location of piles within slope. Based on comparative studies for different combinations of related parameters，the effects of some factors on the stabilizing forces which are required to increase the factor of safety to a desired value are examined systematically.

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THREE-DIMENSIONAL SPENCER METHOD FOR SLOPE
STABILITY ANALYSIS

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2005, 24 (19): -3434 doi:
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[PDF 250 KB] (953)

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The two-dimensional Spencer method is extended to three-dimensional slope stability analysis，in which all forces acting on the discretized blocks are taken into account. The static force equilibrium in all three directions is satisfied；and the total moment equilibrium is also satisfied. In this method，the potential sliding mass is divided into rigid blocks. The inter-block forces and their direction are involved in the computing process. It does not need previously known main sliding direction of the slope. Hence，the number of assumptions being introduced is less than that in other three-dimensional analysis methods. This method can be applied to various types of potential sliding surfaces，complicated geological boundaries and stratifications，water pressure，and earthquake loading，especially for the slope with asymmetrical profile. This proposed method holds the advantages of the 2D Spencer method. The convergence of the iterative calculating process in this method is better than that of other methods. In addition，this method not only gives one value of the safety factors for an integrated slope，but also analyzes the safety factor and its sliding direction for each block according to the characteristics of its sliding surface. The numerical approaches and steps are provided to achieve the program of the proposed method for 3D slope stability analysis. Some programming techniques are also proposed to ensure the practicability and validity of the method. Moreover，an asymmetrical example is employed to show how this method works. The results calculated by this 3D method are given in detail such as the factors of safety and sliding directions of blocks. The results obtained by 3D Janbu method are also presented for comparison. By comparing this 3D Spencer method with other 3D analysis methods，it is shown that the proposed method can provide more parameters and information useful for a landslide control and treatment.

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REVIEW OF BOREHOLE CAMERA TECHNOLOGY

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2005, 24 (19): -3440 doi:
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[PDF 388 KB] (1348)

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Borehole cameras are devices based on optical techniques to provide direct images of boreholes in the form of film or video. Advent of the panoramic technique led to viewing the entire section (360°) of the borehole wall，which is a panoramic image including current depth and compass direction. Digital technique，however，has been utilized to provide a powerful capability of forming，displaying and processing the images. The typical images are the unrolled image and the virtual 3D coregraph. All the images can be used not only to reveal the conditions in the borehole for qualitative identification but also to obtain pertinent information，especially for dip direction，dip angle and aperture of a crack，for quantitative analysis. The borehole camera technology has a wide application to geotechnique，engineering geology，hydraulic and civil engineering，petroleum industry，mining engineering and study on glaciers，etc.. The historical and current development status of the borehole camera technology(BCT) on technology and application are reviewed；and the technical features of devices in each stage，especially for the most representative system of development of the BCT-DBOT(digital borehole optical televiewer)are described. The comparisons of different devices for imaging principle，design of special light source，image processing，image display，image accuracy，etc. are studied；and the digital borehole optical televiewers (DPBCS，OPTV，OBI–40) are widely used in world according to different image processing methods，i. e.，ring by ring method and picture by picture method are distinguished. The merits and shortages of the two methods are illustrated；and the strength and potential development of the borehole camera technology are discussed.

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STUDY ON BRITTLENESS OF GEOMATERIALS

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2005, 24 (19): -3449 doi:
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[PDF 284 KB] (1370)

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How to describe the brittle failure process for geomaterials is a challenging problem. Up to now，there is no harmony among different authors in definition，concept or measurement of brittleness. The concept of brittleness is discussed firstly. Then，a brittleness index describing the brittle change of geomaterials is proposed on the basis of the conclusion of the prior measurement of brittleness，and is verified to describe the brittle change very well. Finally，the binary medium model proposed recently by the authors is used to simulate the stress-strain characteristics of geomaterials under loading conditions；and it is found that the model can duplicate the transference of deformation mode from the strain softening under the low confining pressures to the strain hardening under the high confining pressures；and the brittleness index gradually reduces when the confining pressure is increased.

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INFLUENCE OF DRAWDOWN OF RESERVOIR WATER LEVEL
ON LANDSLIDE STABILITY

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2005, 24 (19): -3454 doi:
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[PDF 283 KB] (1436)

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The reservoir water level in the Yangtze River Three Gorges Reservoir area is adjusted periodically，so the stability of the landslides on both banks is affected seriously. Under the background of the Three Gorges irrigation projects，the influence of drawdown speed of water level on the stability of landslide was analyzed. The variation of the landslide stability at different time during water level drawdown was analyzed considering the actual seepage fields. Through numerical calculation，the relationships of the landslide stability，the seepage coefficient and drawdown speed were obtained. It has some referential values for the study on the sliding stability of slope.

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FUZZY REASONING SYSTEM DRIVEN BY HGA-ANN FOR ESTIMATION OF SLOPE STABILITY

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2005, 24 (19): -3459 doi:
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[PDF 263 KB] (903)

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Fuzziness exists in thinking and judgment of human brains during the procedures of analysis and design of slope engineering，which will bring fussy indefiniteness to some extent to the whole courses of the analysis and design. Thus slope engineering，in fact，is a dynamic，fuzzy，open and complicated nonlinear system，which makes it difficult to evaluate complicated slopes conforming to reality by the traditional analysis method. Artificial neural networks (ANN) and fuzzy reasoning method，which have been applied to the evaluation of slope stability respectively，have shortcomings of their own so that ANN were used to constitute T-S¢s fuzzy reasoning system and the ANNs were trained by hybrid genetic algorithms (HGA). A new fuzzy reasoning system driven by HGA-based ANN，which was used for estimation of slope stability，was constructed. Based on the 80 slope cases that are collected from the worldwide practical slopes，a new estimation method for slope stability is built up. The proposed HGA-ANN-driven fuzzy reasoning system is actually a weighted combination model. Compared with the maximum likelihood method and BP neural network，the presented model has higher predicting accuracy.

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EXPERIMENTAL STUDY ON GLOBAL GEOMECHANICAL MODEL FOR STABILITY ANALYSIS OF HIGH ARCH DAM FOUNDATION AND ABUTMENT

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2005, 24 (19): -3465 doi:
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[PDF 240 KB] (1302)

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Jinping First Stage Hydropower Station is an important cascade hydropower station located on Yalong River in Sichuan Province. The primary mission of this project is to generate power and meanwhile to intercept sand，control flood，store energy. The project adopts a 305 m concrete hyperbolic arch dam which is the highest arch dam in the world. The geological structures in dam site are very complex and the height of the slope is about 1 000 m. There are many different weak structural planes in rock mass of the dam foundation such as fault，lamprophyre dike，innerlayer compressed zone，deep-seated fracture，which are disadvantageous to the stability of the dam foundation and abutment. The global geomechanical model experiment is conducted to study the stabilities of the dam foundation and the abutment of Jinping First Stage Hydropower Station. The model considers the various factors influencing the stabilities of dam foundation and abutment during test，which includes overloading as well as strength-decreasing of weak structural planes in the rock mass of the dam foundation. A kind of model test material called as temperature analogous material whose strength varies with temperature in the process of experiment is adopted to simulate the decreasing of the weak structural planes. The temperature analogous material and model test technique are developed for the first time. Then，the comprehensive method that considers both overloading and strength-decreasing is successfully applied to the model. Deformation characters，failure conditions and mechanisms of the dam foundation and abutment are achieved. The safety evaluation on the model experiment indicates that the global safety factor for the dam foundation and abutment is 4.7－5.0. In addition，the reinforcing measures for the weak areas are advised.

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PROBABILITY CALCULATION OF SLOPE STABILITY BASED
ON ENERGY PRINCIPLE

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2005, 24 (19): -3470 doi:
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[PDF 311 KB] (1029)

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The whole slope can be regarded as a system，and a rule for stability limit-state equation of slope structure was established by systematically disturbing energy method according to energy principle of systemic stability. The calculation method—finite element method，is used to calculate the numerical value of disturbing energy. Due to complexity of slope structure，it is very difficult to obtain accurate formulas of slope structure limit-state function in which the independent variables are random parameters for geotechnical slope. The process and method of approximate analysis formulas，which reconstruct the disturbing energy function of the slope near the checking point by response surface method，are brought forward. Based on the dimensional definition of reliability degree，gradient decline method¾one method of optimization，was introduced to construct the grads declining calculation method of the checking point of approximate limit-state equation that was established through response surface method. There is no need to perform limit-state equation while checking point of limit state equation was solved. The gradient declining calculation method of checking point can avoid the error that was induced by linearization of limit-state equation and can improve calculation speed as well as accuracy of checking point. Finally，the steady reliability degree about an example of terrene slope and an example of rock slope，which are not be reinforced，is analyzed. Stability reliability degree of these slopes can provide important reference to reinforcing and disposal of the project. The results show that the proposed analysis method of slope stability reliability degree has a bright application prospect.

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STUDY ON STABILITY OF UNDERGROUND CAVERN BASED
ON 3DGIS AND 3DEC

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2005, 24 (19): -3476 doi:
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[PDF 749 KB] (1231)

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Three-dimensional geographic information system(3DGIS) has special advantage in respects of visualization and constructing model；and the discrete element method program—3DEC is one of the most matured techniques to solve the problems of structurally controlled failure of engineering rock mass. With the help of FISH language, which is embedded in 3DEC，two kinds of advantage are joined together to provide a powerful tool to perform the consulting work of rock mass stability problems for underground cavern in hydropower engineering.

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BOND STRENGTH BETWEEN ANCHOR GROUT AND ROCK OR SOIL MASSES

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2005, 24 (19): -3482 doi:
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[PDF 271 KB] (1673)

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Based on the related test data of anchorage in rock and soil，the main factors affecting the bond strength between grouting anchor rod and rock or soil are analyzed；and the bond strength value is suggested. It is indicated that the distribution of the bond stress along the fixed length of the anchor rod is nonuniform when the anchor rod is loaded；and the nonuniform degree enhances with the increasing of the fixed length. The former formulae of calculating withdrawal resistance of the anchor rod are irrational for the value of the bond strength is kept constant for the anchor rods with different anchorage lengths. Therefore，the influence coefficient of the anchorage length on the bond strength should be introduced.

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STUDY ON NORMAL DISTRIBUTION CHARACTERISTICS OF CREEP CURVES OF SLOPE DEFORMATION AND WEIGHT DETERMINATION WITH FUZZY OPTIMIZATION

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2005, 24 (19): -3487 doi:
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[PDF 305 KB] (1105)

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The creep curve of rock and soil mass is an important way to describe slope deformation. Three stages of the time-displacement curves are regarded as the basic standard of landslide time determination. Many forecast methods are put forward according to the standard. Results of landslide displacement curve reveal that the shape of creep curve is very similar to that of part of normal distribution curve. The method and corresponding models are firstly presented to fit observation data of creep with renovated normal distribution curve. In view of the fuzzy and random characteristics of the rock and soil engineering，the fuzzy optimization theory is applied to the weight determination in the model calculation；and the weight determination model is given. The model is fitted to all stages of creep curve；so it is promising to realize the whole stage forecast of landslide. The prediction result shows that the proposed method is applicable.

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IMPROVED FORECASTING MODEL TO ESTIMATE STABILITY OF ROCK SLOPE

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2005, 24 (19): -3492 doi:
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[PDF 200 KB] (806)

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The stability of slope is significant in civil engineering，and the structure and physical and mechanical properties of slope rock hold characteristics of macroscopic and microscopic discontinuity，high nonlinearity. The stability of slope is greatly affected by geological structure and its construction. However，these factors are random，fuzzy and changeable，so the slope is an uncertain，nonlinear，dynamic and complicated system；and it is difficult to describe such nonlinear characteristics of this system with traditional methods. Therefore, the stability of large and complicated rock slopes could not be accurately forecasted. A novel forecasting method，which is an alternation and iterative algorithm based on simulated annealing applied in neural network(NN) is presented. Under the same initial conditions，the comparison of the new method with the traditional NN algorithm is conducted；and the result shows the superiority and efficiency of the former. Based on comprehensively analyzing the mechanism of stability loss of rock slopes and the main factors affecting the stability of rock slopes，the compound indices were proposed for forecasting model as influencing factors. Then，the cases of rock slopes in hydropower projects are taken as training samples and the unlearning cases are forcast；and the results is satisfying，showing that the forecasting accuracy is superior to traditional BP neural network. Therefore，the forecasting model put forward here can get safety factor of different rock slopes quickly and accurately；and it can provide a new approach for selecting slope design economically and rationally.

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RESEARCH ON ARTIFICIAL NEURAL NETWORK-TIME SERIES ANALYSIS OF SLOPE NONLINEAR DISPLACEMENT

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2005, 24 (19): -3499 doi:
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[PDF 220 KB] (1696)

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As an explicit behavior of the complicated dynamic system，the displacements of slop are characterized with randomness and indetermination involving many uncertain factors；and the physical-based modeling is very difficult to fulfill prediction function. As an alternative，it was proved by many practical engineering cases that a set of displacement time series to predict the future displacement can be used. Based on the principles of artificial neural network and time series analysis，the BP network is established by zero mean method，standard deviation preprocess，regularization energy function, and Bayes-regularization to extract the trend term of displacement time series. After the extraction，the displacement time series becomes a balance series, which could be processed by normal ARMA model. In addition，combined with the real-time tracing algorithm，the artificial neural network-time series analysis(united modeling)for nonlinear displacement in geotechnical engineering was proposed. As a test，this modeling was used in displacement prediction of Geheyan Hydraulic Power Station intake slope and Dayantang slope in Shuibuya Hydraulic Power Station project. The results of engineering case indicate that it is reliable with high precision. It is proved that this modeling can be used to practical engineering.

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MODELING EXPERIMENT STUDY ON FAILURE MECHANISM
OF COUNTER-TILT ROCK SLOPE

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2005, 24 (19): -3505 doi:
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Based on the example of a certain slope in Guangdong segment of Beijing¾Zhuhai Expressway，several groups of physical model tests are performed；and the factors affecting the stability of slope are analyzed. The testing results show that the main failure mode of counter-tilt slopes is a toppling one，which appears first on the top of the slope. The stability of counter-tilt slopes does not rest on terrane obliquity but on strength and thickness of terrane interface. It is also indicated that the failure characteristic of this kind of slope is similar to that of superposition cantilever；and the anti-toppling capability of counter-tilt slope increases with the increases of the parameters such as the parameters of interface (c，j)，thickness，and obliquity of terrane.

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STUDY ON STRENGTH FRACTAL FEATURES OF ACOUSTIC
EMISSION IN PROCESS OF ROCK FAILURE

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2005, 24 (19): -3512 doi:
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[PDF 184 KB] (1295)

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Through the acoustic emission(AE) experiments in the process of rock failure，the strength fractal model of acoustic emission in the process of rock failure is established. The AE fractal features of all stress levels in the whole rock failure and the changing rules of fractal value, which varies from time to time，are studied. The results show that，in the initial stage of loading，the AE fractal value of rock samples is unsteady. But from the viewpoint of the general changing trend，the fractal value in this period still remains greater. In the middle and later stage，the fractal value has obvious regularity, changing from great to small. The fractal value reaches to the minimum at the critical point of sample failure. Since it is difficult to confirm the minimum fractal value (critical value) in practical application，it is found that the continually declining fractal value is the premonitory feature of rock failure. Consequently，it provides theoretical basis and means for in-situ rock mass monitoring and forecast by acoustic emission parameter.

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AN ELASTOPLASTIC ANISOTROPIC DAMAGE
MODEL FOR FROZEN SOIL AND ITS DAMAGE ANALYSIS

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2005, 24 (19): -3517 doi:
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[PDF 207 KB] (1072)

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Abstract：On the basis of irreversible thermodynamic theory，an elastoplastic anisotropic damage constitutive model is presented by introduction of a plastic potential function considering the volume change of frozen soil. The anisotropic damage evolution equation is derived from the damage accumulated potential function, which is constructed in the space of the damage strain energy release rate that is conjugated with damage tensor. Triaxial tests are chosen to illustrate the application of this model，and good agreement between experimental data and numerically simulated ones is obtained. The calculated results indicate that the amount of elastic damage only accounts for a small percentage of total structural damage of frozen soil，and most part of damage takes place during the plastic deformation phase. The increase in confining stress can strengthen the structure and reduce the amount of total damage of frozen soil.

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STUDY ON SOIL-COMPACTING EFFECTS INDUCED BY EARTH PRESSURE BALANCE SHIELD CONSTRUCTION

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2005, 24 (19): -3522 doi:
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[PDF 447 KB] (921)

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Earth pressure balance(EPB) shield construction often has soil-compacting effects on its surrounding soil. It results in the surface upheaval and moving away of deep soil from the tunnels. The soil is assumed to be a kind of uniform linear-elastic material and the initial stress field of the soil is considered. Through the simulation of soil-compacting process by applying an outward elliptic radial displacement to the surrounding soil of shield，the approximately analytical solutions of soil displacement fields in half space are obtained in small strains. Considering the spatial effects，the modified calculation formula is presented. Also，the analysis of computation for a case by proposed formula is made. It shows that excessive support pressure，deflexion of shield，the friction between shield and soil，and the grout pressure will induce the compacting effects. The maximum surface upheaval is at both sides of axes. In addition，the heaving process will reduce the total magnitude and width of the ground surface settlement troughs after the construction being completed. The calculated results here are in accordance with the measured ones.

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ANALYSIS OF BEDDING-SLIP FAILURE MECHANISM OF
ROCK SLOPE DUE TO HYDRAULIC DRIVE

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2005, 24 (19): -3529 doi:
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[PDF 216 KB] (1368)

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The stability of bedding rock slope is mainly affected by two factors，which are physico-mechanical properties of slide face and groundwater pressures. Based on analysis of formation and evolvement of rock slope bedding-slip failure due to hydraulic drive，the effect mechanism of groundwater on bedding rock slope stability is discussed. It is pointed out that groundwater flows through the passage that consists of the slide face and the top splay fracture of a rock slope produces static water pressure of splay fracture，flotage and haulage of slide face. Equations for calculating the critical water highness in the splay fracture and the critical rainfall intensity are developed. It is shown that：(1) water pressures above increase with increasing the water highness of the splay fracture；(2) the slope will lose its stability once the water highness of the splay fracture reaches to a critical value；and (3) the water highness of the splay fracture is linear with the rainfall intensity. The bedding-slip failure criterions of rock slope are put forward at length.

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EFFECTS OF ELASTIC BOUNDARY IN GROUND ON
DISPLACEMENT FIELD INDUCED BY SHIELD TUNNELING

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2005, 24 (19): -3534 doi:
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[PDF 346 KB] (995)

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Engineering practices show that the existence of underground structures or obstacles severely influence the distribution of displacement produced by shield tunneling across them. To analyze and predict magnitudes and the characteristics of the ground deformation induced by shield tunneling across the adjacent underground objects, the boundary element method is deduced considering the underground objects as the elastic boundary. According to the small deformation hypothesis of the elastic theory and coordination conditions of elastic boundary，the ground displacement fields can be obtained by superposition of the displacement fields produced by shield tunneling and reaction forces on the elastic boundary. The displacement caused by reaction on the elastic boundary can be achieved by the theory of Winkler elastic foundation. Analytical results based on the above mentioned principles indicate that there are great differences about the characteristics of the ground displacement fields with/without considering the elastic boundary. The existence of the underground objects obstructs the propagation of the ground movement and makes the accumulated displacement near them. So，there is an important signification in accurate prediction and precontrol of the displacement fields subjected to the adjacent advance of the shield by considering the effect of the elastic boundary. In practice，the critical control distance can be calculated by the proposed method，which could be employed in precontrol of shield construction and secure the safety of adjacent protected objects.

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RESEARCH ON ELECTROMAGNETIC RADIATION RULES OF COMPOSED COAL-ROCK BURST FAILURE

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2005, 24 (19): -3541 doi:
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[PDF 238 KB] (1104)

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It is known that wide frequent electromagnetic radiation(EMR) signals can be produced in the processes of deformation and failure of coal and rock by many theoretical researches and physical experiments. So，the EMR rules of deformation and failure of coal and rock body composed of hard roof，coal body and floor are important to predict and forecast the coal and rock dynamic calamity. The EMR and acoustic emissions(AE) phenomenon in the rock burst process are investigated by using the Disp-24 acoustic-electromagnetic system and MTS loading system in the laboratory. The results show that the intensity of EMR signals rises slowly before burst failure but increases suddenly when burst failure occurs. The counts of AE signals increase suddenly to maximum value before failure，and suddenly decline. During the period of impact rupture of combined samples，the time when signal peaks of EMR and AE appear are not synchronous，and the maximum EMR signals appear at stage after peak stress. However，the maximum AE signals appear at the peak stress. The AE signals are comparatively weak when EMR signals reach to peak values；and EMR signals are comparatively weak when the AE signals reach to maximum values. With the achieved rules，the danger of rock burst can be evaluated and forecasted.

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A FLAC3D METHOD FOR CALCULATION OF RESIDUAL SUBSIDENCE IN A MINING AREA BENEATH AN EXPRESSWAY

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2005, 24 (19): -3545 doi:
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[PDF 397 KB] (1380)

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The calculation of residual subsidence in mining area is a quantitative method to evaluate hazards rank derived from the mining area. The reliability，accuracy and operation of the calculation directly affect the choice and assessment of the scheme for reinforcing mining areas. Based on the mechanical characteristics of collapse，the parameters of traverse wave or Rayleigh against static rock mass are used to determine assessment indices for the parameters of engineering rock mass. Under the current status of collapse of a mining area，FLAC3D software is used to calculate and evaluate the residual subsidence of the mining area beneath an expressway；and the advantage of the method is discussed as compared to other calculation methods of residual subsidence. Through a case study of a reinforced mining area，the testing data show that the proposed method is accurate and reliable，and it can provide a new way to evaluate and calculate the residual subsidence in mining area beneath an expressway.

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ANALYSIS OF HIGH SLOPE ROCK DEFORMATION AND SAFETY PERFORMANCE FOR LEFT BANK OF LIJIAXIA ARCH DAM

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2005, 24 (19): -3551 doi:
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[PDF 491 KB] (1100)

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The safety and stability problems of high rock slope，such as weaken massif，fully developed geological conformations，widely unloaded or flabby rock layer，and squirming or sliding rock，are often encountered in engineering practice. So，it is very important to enforce the high slope rock deformation monitoring，and to process and analyze the measuring data timely. The high slope of the left bank of Lijiaxia arch dam is given as an example to search the method of how to analyze and evaluate the safety performance of high slope by utilizing rock deformation monitoring data. Based on space-time qualitative analyses of the dam-site valley breadth，slope rock deformation monitoring data measured after the first reservoir impounding，and physical genesis analysis of doubtful rock deformation points，the progressive regression models of rock deformation survey points were set up by using the least-square method；and the results of model simulation and partition to the variational extension of annual deformation of all surveying points were utilized to analyze the influencing effects of the independent variable factors such as hydraulic pressure，temperature and time-effect related to the high slope rock deformation. The conclusions obtained from synthetical analysis of the deformation monitoring data of the left bank of Lijiaxia arch dam are as follows：(1) the high slope rock principally slided downwards the riverbed during the period of impounding water being escalated to normal reservoir level；(2) the rock deformation of the high slope gradually tended to converge and keep stable after January，2002，when the impounding water rose to normal reservoir level，and now the safety performance of the left bank is normal；and (3) presently，part of the left bank rock still tends to slide downwards slightly. So, a suggestion is proposed to strengthen the safety monitoring.

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RESEARCH ON DYNAMIC COMPUTATION FOR SHOTCRETE AND ROCK BOLT SUPPORTING AND INTEGRAL LINING STRUCTURES IN ROCK MASS

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2005, 24 (19): -3561 doi:
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[PDF 305 KB] (830)

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Under the explosive load，shotcrete and rock bolt support and integral lining structures are usually used for chambers in rock mass. The analytic solution for dynamic analysis of circular chambers under the plane strain is presented through theoretical research；and different structural thicknesses and different stiffnesses of rock masses are calculated. The obtained results are accordant with those of macroscopic qualitative analysis and can provide a valuable reference to verifying validity of numerical calculations.

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MINE PRESSURE MEASUREMENT IN COAL PILLAR
AND ITS APPLICATION TO ROADWAY DRIVEN CLOSE TO GOAF

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2005, 24 (19): -3566 doi:
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[PDF 205 KB] (867)

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Roadway driving close to the goaf is one of the effective methods to reduce the non-mineable coal reserve confined in the pillar and to raise coal productivity. The method is widely applied in the coal mines with relative simple hydrogeological conditions，such as the coal mines in North Anhui Coal Field，Lu′an Coal Field and so on. Because the stress condition in roadways close to goaf is rather different from the normal ones，the goaf roadways have high strata pressure and it is difficult to maintain. In order to solve the problems，many scholars have made site investigations by observation，numerical and physical simulations，and the structural analysis of the roof strata. But few long-term observations about mine stress and roof-floor closing displacement in the coal pillar, in which the goaf roadways are planned to drive, are reported. To understand the stress and the displacement，a special appendix opening is driven from the roadway in work face 655，the Second Liuqiao Coal Mine；and the measurements were made for about 146 days. According to the observation，it is found that the pillar can be classified as 3 zones in stress conditions as follows：(1) the plastic zone，0－4 m from the edge of the pillar；(2) the zone of abutment pressure on integrated coal，4－10 m from the pillar；and (3) undisturbed zone，10 m and above. In plastic zone，the strata pressure is reduced with time, and the reducing speed is attenuated with time to zero after 146 days when the coal was mined. The strata pressures in other zones remained high during the observation. Therefore，the suitable place for the goaf roadway is seen in the plastic zone；and the pillar between the roadway and the goaf should not be larger than 4 m and not be earlier than 146 days after the coal is mined. The achieved results are successfully used in the mines of northern part of Anhui Province.

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GROUNDWATER ACTION LAW AND EVALUATION ON DYNAMIC STABILITY OF HUANGLASHI SLOPE IN THREE GORGES REGION

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2005, 24 (19): -3571 doi:
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[PDF 442 KB] (1150)

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Taking the typical accumulative slope of Huanglashi as an example and considering the special role of groundwater in landslide，the effects of the groundwater seepage on the stability of the landslide are studied quantitatively. The calculating method of seepage is adopted in which the groundwater level approaches to the real situation；and the head of groundwater and the seepage pressure are calculated when the groundwater level changes in the seepage flow field of the Huanglashi slope. Therefore，the role of the groundwater in the Huanglashi slope is quantitatively analyzed. It is found that the maximum value of the seepage pressure is located in the former part of the slope. On the basis of the result，the calculation of seepage pressure is drawn into the Spush method. According to the mean monthly water level，the relationships of the stability coefficient with the time is calculated，respectively，when the seepage pressure is(or not) taken into account. According to the calculation results，the stability coefficient has the decreasing tendency under the periodic action of seepage，and the maximum reduction is seen to be 0.202 0 and it happens when underground water level declines rapidly. It shows that the abrupt decline of underground water level is the most disadvantage factor，and the effect of the seepage pressure on the stability of the Huanglashi slope has increasing tendency. In terms of the former analysis results of the groundwater action law and the distribution of seepage pressure，as well as the actual local situation of the slope，the prevention and control methods are proposed.

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PATTERN RECOGNITION AND POSSIBILITY PREDICTION OF COAL AND GAS OUTBURST

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2005, 24 (19): -3577 doi:
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[PDF 647 KB] (1268)

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The study of coal and gas outburst with multi-factor pattern recognition method is related to coal mining，safety engineering，geology engineering，geographic information system(GIS)，probability theory，information science，and artificial intelligence(AI). Based on theoretical analysis and the relation among the factors that affect coal and gas outburst，the norm and model of pattern recognition are established. Then the design and algorithm of pattern recognition system are completed，on which the probability prediction norms are certain and the development of coal and gas outburst prediction system is completed. With eight factors including active fault，maximal stress，gas pressure，and gas content acting as the main discriminant，the pattern recognition method was used to perform possibility prediction of coal outburst；and the mining area was then divided into coal and gas outburst dangerous area，threaten area and safe area，respectively，to assess and predict the danger of coal and gas outburst. Thus the accuracy of coal and gas outburst prediction is improved. By the method，a comparatively scientific region prediction of coal and gas outburst are built；and it is possible to judge and precontrol the coal and gas outburst.

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CONSTRAINTS TREATMENT OF FIXED BOUNDARY IN NUMERICAL MANIFOLD METHOD

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2005, 24 (19): -3582 doi:
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[PDF 266 KB] (951)

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In numerical manifold method，fixed boundary is treated by penalty function method. The arrangement and value of penalty spring will affect the effect of numerical modeling；and work is complex. Based on the composition of displacement function on manifold element，a new method of constraints treatment of fixed boundary is proposed；and it changes the constraints treatment of fixed boundary into the constraints treatment of generalized node；and the constraints condition will be met strictly by using special cover function on physical cover；and then corresponding stiffness matrix is deduced. New method had been proved theoretically that it is correct；and it not only meets strictly the constraints condition in physical meaning，but it has simplified work of treatment. It is helpful for programming and the application of numerical manifold method to engineerings.

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ANALYSIS OF DISPLACEMENTS OF TUNNEL-TYPE ANCHORAGE FOR
A LARGE-SPAN SUSPENSION BRIDGE

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2005, 24 (19): -3588 doi:
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[PDF 461 KB] (1089)

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The tunnel-type anchorage of Siduhe Bridge is used for the first time in large-span suspension bridge in China. Based on the rockmass parameters from tests，the three-dimensional elastoplastic analysis has been performed to simulate the complete sequence of construction including highway tunnel excavation，tunnel-type anchorage excavation，concrete in-situ casting，prestressed concrete anchorage，main cable installation，etc.. By using 8-node 3D brick elements，the surrounding rockmass and concrete anchorage bodies are simulated. Shotcrete and lining are simulated by 4-node shell elements. A modified Mohr-Coulomb model is adopted for the rockmass. Stress relaxation in surrounding rock due to excavation is simulated by field-dependant deduct elastic modulus method. The maximum vertical displacement of the top rock is 2.3 mm and that of the bottom rock approximates zero after anchorage concrete being cast. The displacements of the surrounding rock are independent of each other under designed cable force；and the displacement field approaches to same when the cable being overloaded. The failure pattern is that two anchorage bodies are pulled out which decline outsides. The magnitude of displacements in the surrounding rock is graded in mm，which is far below the allowance value of displacement on tower top. The results of the numerical analysis are used in the design of the tunnel-type anchorage.

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DEFORMATION MECHANISM AND CONTROL OF MINING-INDUCED TOPPLING-DISPLACEMENT

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2005, 24 (19): -3594 doi:
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[PDF 366 KB] (1193)

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Slopes of toppling-displacement generally have the structures of reversed dip；and the deformation process and deformation mechanism are considerably complicated. The deformation range of rock mass involved is comparatively large，which will produce serious harm. Through tracing analysis of monitoring data for the rock mass displacements，numerical simulation tests for typical high slope of toppling-displacement are performed in Fushun West Opencast Coal Mine. The deformation mechanism of toppling-sliding mass and its effect on deformation of ground are analyzed and investigated under the effects of mining activities. Analytical results indicate that mining under the particular geological structure and mining engineering condition causes the problems of toppling deformation. Reversed section of slope deformation plays a key role in the deformation for the whole slope；and the surface foundation deformation is mainly caused by toppling-sliding mass，which is located in the south of faults；and renovation plan for practical problem is proposed.

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邱战洪博士论文摘要

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2005, 24 (19): -3599 doi:
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[PDF 95 KB] (886)

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邱战洪博士论文摘要

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徐涛博士论文摘要

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2005, 24 (19): -3600 doi:
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