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2004, 23 (09): -0 doi:
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COUPLING ANALYSIS ON SEEPAGE AND DAMAGE IN FRACTURED ROCK MASS

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2004, 23 (09): -1413 doi:
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[PDF 287 KB] (1225)

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By introducing a concept of additional hydraulic pressure-induced flexibility tensor and considering effects of damage behavior on permeability tensor of fractured rock mass，the coupled behavior of stress and seepage is analyzed. Based on above analysis，a model for coupling analysis on fluid flow and damage is developed. The results obtained from theoretical and practical analysis show that the influence of hydraulic pressure on damage behavior and effects of damage on distribution of hydraulic pressure can not be ignored when there is fluid flow in fractured rock mass.

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ANALYSIS ON CREEP COMPLIANCE OF CRACKED ROCK

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2004, 23 (09): -1419 doi:
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Using Betti reciprocal theorem and viscoelastic fracture theory，the formulation of creep compliance of cracked rock under uniaxial stress and hydrostatic stress is deduced. Influence of crack interaction on creep compliance of cracked rock is taken into account by using self-consistent theory，and variation principles of creep compliance of cracked rock with increased crack density parameter and Poisson¢s ratio are analyzed. Difference of creep compliance with and without crack interaction is analyzed，and the creep stability of cracked rock under hydrostatic stress is discussed.

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TIME-DEPENDENCY OF NEUTRAL SURFACE FEATURE OF MID-THICK SOFT ROCK PLATE UNDER STATIC LOAD BENDING

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2004, 23 (09): -1424 doi:
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[PDF 185 KB] (994)

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In the local or global movement of rock mass under mining，overlying strata play a key role. The overlying strata movement is a complicated space-time process and has time-dependent feature. Based on Burger model，the time-dependent feature of neutral surface of mid-thick soft rock plate under static load bending is studied by mid-thick plate model. The results show that the location of neutral surface of mid-thick soft rock plate will change with time in a long period and is affected by the stiffness and viscometric parameter of rock mass. For rock mass under mining，the support of surrounding rock mass in initial stage is critical to the stability of surrounding rock mass.

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QUANTITATIVE ANALYSIS ON DAMAGE EVOLUTION OF INTACT EXPANSIVE SOIL DURING TRIAXIAL SHEARING TEST

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2004, 23 (09): -1428 doi:
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[PDF 282 KB] (1211)

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Based on the computerized tomography(CT) scanning results of natural expansive soil during triaxial shearing test，a damage variable of natural expansive soil is derived from the computerized tomography scanning data，and the damage evolution equation of expansive soil during shearing is also developed.

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RESEARCH APPROACH ON INCREMENT OF WORK AND ENERGY—— CATASTROPHE THEORY OF ROCK DYNAMIC DESTABILIZATION

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2004, 23 (09): -1433 doi:
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The paper demonstrates that the rock dynamic destabilization and the destabilization of geometry form of the elastic body are two essentially distinctive phenomena，which correspond to different catastrophe models. The mistakes existing in the research of rock dynamic destabilization by using catastrophe theory are pointed out. For the stabilization of elastic body with equilibrium branch point，some concepts and main points in the solution of total potential energy function are expounded. For rock dynamic destabilization without equilibrium branch point，in which the system equilibrium relation can be expressed with quasi-static displacement on the stage before and after the period of rock system coming into destabilizing，the equilibrium relation of work and energy increment can be established according to energy conservation principle. The equilibrium relation of work and energy increment is different from that of potential energy function. The equilibrium equation of catastrophe model that corresponds to the destabilization question of rock system can be deduced by the equilibrium relation. All main characteristics，demonstrated by the equilibrium equation and the equilibrium curved surface，is of one-to-one correspondence to the primary characteristics of destabilized prototype.

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REMOTE SENSING-ROCK MECHANICS(VII)——THERMAL INFRARED IMAGING DETECTION OF ROCK IMPACTION WITH LOW VELOCITY

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2004, 23 (09): -1439 doi:
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[PDF 295 KB] (1185)

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By means of thermal infrared imaging detection on the transient process of rock impact with low velocity，the experiments with variable impacting angle，moisture and lithology are carried out. It is discovered that (1) there exists a critical velocity when rocks subjected to a normal impact，and the critical velocity varies with the rock types and it is about 15 m/s for marble，(2) the radiant characteristics are closely related to the impacting factors，and as to marble subjected to a normal impact within the critical velocity，the increment of thermal infrared (TIR) radiant flux is of linear correlation with the impaction kinetic energy，and the increment of TIR temperature is of conic correlation with the impacting velocity，(3) the radiant characteristics varies with the impacting angle，the radiant intensity in normal impact is almost the weakest，and it reaches the maximum value when the angle is about 45°，and (4) wet and dry rocks show difference in radiant characteristics under impact，and the trend of difference is relevant to the velocity.

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INHOMOGENEITY ANALYSIS OF DAMAGE UNDER
UNIAXIAL TENSION (I)——BASIC THEORY

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2004, 23 (09): -1446 doi:
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[PDF 210 KB] (954)

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The localization of damage variable (rate) is investigated. Based on non-local theory，the damage variable is non-local variable and is dependent on local damage variable and its second spatial gradient. After onset of damage localization，the constitutive relation is considered linear strain softening. The boundary condition between elastic and damage zones where the local damage is zero is used and the assumption that the width of damage zone is determined according to maximum local damage variable is adopted. The analytical solutions of local damage variable，local damage variable rate and width of localized damage zone at strain softening period are obtained. Besides，the presented definition on relation among tensile stress，tensile strain and non-local damage variable is different with traditional expression in that the coefficient of non-local damage variable is 2，not 1，in the presented definition. The advantage of the present definition is that when specimen is completely separated into two pieces，the maximum local damage variable can reach 1，which agrees with general knowledge. The average value of local damage variable in the rang of damage localization zone is the non-local damage variable. In addition，the maximum local damage variable is two times of the average damage variable.

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RESEARCH ON SURROUNDING ROCK EVALUATION OF UNDERGROUND ENGINEERING BASED ON EXTENSION METHOD

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2004, 23 (09): -1450 doi:
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The extension method is introduced in this paper，and the matter-element model for evaluating surrounding rock stability of underground engineering is established. The research indicates that the extension method is reasonable and feasible in evaluating surrounding rock stability，and it can well reflect every evaluating factor’s influence on surrounding rock stability. The factor weight is determined by using simple dependent function，and this can avoid the effect of subjective factor of human in practices.

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SEDIMENTARY ROCK MASS STRUCTURE TYPES AND THEIR
INFLUENCE ON UNDERGROUND PRESSURE IN COAL MINING

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2004, 23 (09): -1454 doi:
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[PDF 361 KB] (1015)

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The mechanical properties of the sedimentary rock mass structures depend on the lithological characteristics of rock and different types of structure planes. The percent content K of stiff rock is select to represent lithologic characteristics in the layered rock mass，and the rock mass is classified as stiff，middle stiff and soft rock masses. Based on developing degree of structure planes and scale of project，rock mass structures of coal roof are divided into intact，blocky and heavily fractured structures. Through simulation test of similar materials，the underground pressures of the working faces with different rock mass structures are analyzed. The test results indicate that the abutment stress ahead of working face reduces from intact structure to blocky and heavily fractured one，and the position of peak abutment stress migrates inside to roof rock mass.

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STUDY ON MECHANICAL EFFECT AND COAL PILLAR STABILITY
DURING HIGHWALL MINING WITH AUGER MACHINE

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2004, 23 (09): -1460 doi:
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[PDF 246 KB] (1027)

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Using numerical simulation FLAC，analysis is made on the distribution characteristics of stress and plastic zone in the working faces and coal pillars during highwall mining with auger machine. The mechanical effect and damage mechanism are studied of coal pillars when pillar¢s width or vertical septum between the working faces is reduced，which provides the basis for the design of coal pillars and working faces during highwall mining with auger machine.

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APPLICATION OF SELF-ADAPTIVE TIME SERIES MODEL TO
DISPLACEMENT FORECAST IN UNDERGROUND ENGINEERING

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2004, 23 (09): -1465 doi:
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[PDF 246 KB] (797)

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The principle of self-adaptive time series model is introducing filter theory to time series analysis. The self-adaptive time series model can，to some extent，modulate model parameters according to the input and output data，and adjust them to its optimal values in some statistical conditions through the iterative algorithm. The satisfying forecasting results may be obtained even if only part of the statistical properties is known，which is proved by two examples of modeling and forecasting of the convergent displacements of tunnels. The presented model is also useful to forecast the stability of surrounding rock and support structure of tunnels.

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BACK ANALYSIS OF SEEPAGE WITH ANN BASED ON ALTERNATIVE
AND INTERATIVE ALGORITHM

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2004, 23 (09): -1470 doi:
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[PDF 190 KB] (984)

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Aimed at some limitation of the traditional BP Neural Network，a global optimal algorithm is put forward based on alternative and iterative algorithm，and the corresponding program of FORTRAN is developed. With the same initial condition，the Neural Network based on alternative and iterative algorithm is compared with that based on the traditional algorithm，and the characteristic and excellence of the former algorithm are explained. As an example，based on the nonlinear characteristic of ANN and 3D seepage flow FEM computation，the method combined with inversion principle is applied to the sluice foundation and the percolation parameter ratio is obtained. Compared with the actual value，the obtained result is accurate，which illuminates the reliability of the algorithm in back analysis.

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ANALYSIS OF CONSTANT-PRESSURE WELL TEST DATA FOR LOW-PERMEABILITY FRACTURED ROCK MASS

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2004, 23 (09): -1476 doi:
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[PDF 189 KB] (1114)

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According to the theory of fracture flow，the theory and methods to analyze the hydraulic and geometric properties of fractured rock using constant-pressure well test data are given. Two approaches to determine these properties are introduced with practical examples. The first one uses standard curve matching approach to analyze test data for flow of arbitrary dimension，and the second one uses straight-line approach chart method for flow of integer dimension of one，two and three.

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FUZZY RELATIONAL ANALYSIS ON SELECTION OF c AND φ
FOR ENGINEERING ROCK MASSES

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2004, 23 (09): -1481 doi:
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[PDF 276 KB] (1042)

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In this paper, the key factors influencing c (cohesion)and φ (internal friction angle) of engineering rock masses is abstracted with consideration of physical and mechanical properties of rock masses. The selection method of c and φ values is discussed based on the fuzzy comprehensive judgment theory and an improved weight calculating method is proposed by means of the grey relation degree. The results show that the presented method is more efficient than that of the empirical formula.

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3D JOINT PERSISTENCE CALCULATION THROUGH RANDOM SIMULATION

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2004, 23 (09): -1486 doi:
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Based on statistics of randomly distributed joints in rock mass，the expectations and the associated degree of confidence of joint geometry can be obtained. Then，the three dimensional map of fissured rock mass can be simulated by Monte-Carlo method. Based on investigation on the failure surface property of many projects，3D joint persistence of rock mass is defined. By using the rock-bridge failure theory and three dimensional surface approximating method，the persistence can be easily calculated.

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OBTAINING RQD OF ROCK MASS BY SAMPLING WINDOW METHOD

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2004, 23 (09): -1491 doi:
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[PDF 256 KB] (1432)

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Rock quality of designation (RQD) is an very important index in rock mass quality evaluation. But the reliability and engineering application of conventional RQD are limited by the direction，the number of the bore holes available in investigation and hence the notable errors. The method of obtaining RQD of rock mass by sampling window is presented in this paper. Setting scan lines in all the directions automatically by computer program，the errors can be reduced and anisotropic properties of rock mass can be synthetically reflected by this new method，and a large number of RQD can be easily obtained. The method is simple and easy to handle in engineering application.

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STUDY ON SPATIAL ACTION BETWEEN HIGH BUILDING
FOUNDATION AND UNDERGROUND SHELTER CAVE

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2004, 23 (09): -1496 doi:
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[PDF 397 KB] (1230)

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By using 3D node-adjustable elasticoplastic finite-infinite-shell element coupling calculation model，the spatial action between the building foundation of Guangzhou New-China mansion and the existed underground shelter cave is analyzed in this paper. The calculated displacement of underground cave under foundation load is compared with measurement results in site and is approved reliable. The safe distance between building foundation and underground cave and some other concerned conclusions are obtained. The study results not only serve as important inference to the construction of this case，but also accumulate experience and data for other similar engineering practices.

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STUDY ON INFLUENCE OF SOFT SOIL ON DYNAMIC CHARACTERISTICS OF UPPER STRUCTURE

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2004, 23 (09): -1502 doi:
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[PDF 264 KB] (1085)

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In a wide frequency domain，vibration mode of a soil-pile-structure system on vibration table is investigated by experiment and FEM analysis. Then the influence of soft soil on the dynamic characteristics of upper structure is discussed. The dynamic characteristic of one order，which is corresponding to soft soil，is also pointed out when relative dynamic stiffness ratio of soil to upper structure is small enough.

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SEISMIC RESONANT CATASTROPHE ANALYSIS OF NONLINEAR FOUNDATION-STRUCTURE SYSTEMS

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2004, 23 (09): -1509 doi:
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[PDF 437 KB] (1128)

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On the basis of system energy，the dynamic equations of nonlinear foundation-structure system are derived from Lagrange equation. The asymptotic solution and corresponding calculation results of amplitude- frequency are presented in seismic resonant area by means of asymptotic method (KBM)，and then the influence of foundation parameters on properties of structure amplitude-frequency is analyzed. It is indicated that structure response emerges complex nonlinear properties along with the change of foundation parameters，such as distortion of resonant area，amplitude catastrophe，path effect and hysteresis，and there is the unstable resonant area between tow points of catastrophe. The value change of parameters of the same foundation type causes remarkable influence on structure dynamic properties. The calculation error by the current code of seismic design might be obvious for the analysis of nonlinear foundation-structure system. The nonlinear properties must be considered in order that design parameters are more reasonable and optimal.

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ANALYTICAL THEORY OF LATERAL VIBRATION OF SINGLE PILE IN VISCO-ELASTIC SUBGRADE CONSIDERING SHEAR DEFORMATION

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2004, 23 (09): -1515 doi:
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[PDF 221 KB] (987)

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The Beam-on-Dynamic-Winkler-Foundation (BDWF) model is utilized to determine the lateral dynamic response of single pile in viscoelastic subgrade. Based on frequency-dependent stiffness and damp coefficients，and with the pile modeled as a Timoshenko beam considering both bending and shearing，a more rigorous analytical solution on lateral vibration of a single pile is developed. By comparing the presented theory and that based on Euler beam model，the critical length of pile in homogeneous soil is obtained by modeling the pile as a Euler beam. In most cases, this critical length is about 8 times diameter of pile and it is nearly independent of dimensionless frequency and the ratio of Young’s modulus of the pile to that of the soil. It is also found that neglecting the shear deformation of pile will lead to a relatively smaller calculation result，which is not safe in engineering application.

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STUDY ON FROST-HEAVING FORCE IN RETAINING STRUCTURE WITH ROW-PILE AND FROZEN SOIL WALL FOR DEEP FOUNDATION PIT

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2004, 23 (09): -1521 doi:
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[PDF 195 KB] (991)

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Based on the mechanism analysis of frost-heaving force emerging in the retaining structure with row-piles and frozen soil wall for deep foundation pit，releasing-pressure holes are used to reduce horizontal frost-heaving force. By numerical simulation，the values of horizontal frost-heaving force against row-piles are obtained in the condition with or without releasing-pressure holes. The results indicate that using releasing-pressure holes can sharply reduce the horizontal frost-heaving force against row-piles, and the relationship between horizontal frost-heaving force and thickness of frozen soil wall is given out. The research results can provide designing basis for engineering practice of the new type of retaining structure.

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CONSTRUCTION MECHANICS RESPONSE STUDY
OF HIGHWAY TUNNEL IN KARST

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2004, 23 (09): -1525 doi:
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[PDF 506 KB] (1267)

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Because of the influence of karst，the construction mechanics response of highway tunnel in karst differs from that of common tunnel. Through large conformable model testing and FEM，the influence of karst cave magnitude and position on construction mechanics response is studied，and some distribution rules of displacement field and plastic field of tunnel in karst are summarized.

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CALCULATION METHOD OF LENGTH OF ANCHORING SEGMENT
FOR PARTIAL-COHESIVE CABLE

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2004, 23 (09): -1530 doi:
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[PDF 252 KB] (1175)

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According to analysis on pulling test results of bolt and comparison of the mechanical status of anchoring segment between bolt and cable，the distribution model of shear stress along the anchoring segment of partial-cohesive cable is put forard. The shear stress reaches the maximum not right at the midpoint of anchoring segment but at side near ground surface and reduces to 0 at the ends of anchoring segment. A reasonable calculation method of the length of anchoring segment is given. The main control condition is that the maximum shear stress of anchoring segment can’t exceed the value of cohesive strength divided by safety factor. The calculation method of length of anchoring segment is shown in detail by a practical example in the paper.

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NON-LINEAR ANALYSIS ON PRESTRESSED CABLE

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2004, 23 (09): -1535 doi:
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[PDF 285 KB] (1037)

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Firstly anchoring body of prestressed cable is discretized，and prestressed cable system is decomposed into two parts，anchoring body and rock，which are investigated separately. Secondly，the 3D stress of arbitrary point of rock is calculated based on Mindlin stress solution and stress superposition principle. The deformation of arbitrary point of rock under prestress loading is determined according to modified layered summation, and the deformation of anchoring body is obtained according to loading transfer differential equation. Then，the compatibility equation group of loading and deformation is established. Lateral resistance distribution and deformation character of prestressed cable is obtained with iterative method. A case calculation with comparison with test results shows that the presented methodology is reasonable.

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APPLICATIONS OF ARTIFICIAL NEURAL NETWORKS AND GENETIC ALGORITHMS TO ROCK MECHANICS

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2004, 23 (09): -1542 doi:
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[PDF 307 KB] (1727)

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The studied problems in rock mechanics and rock engineering are abundant. Various new requirements are coming out frequently in real engineering problems，which cannot be solved using traditional methods. It has become a hot topic to use advanced ideas and techniques from other disciplines for reference to solve the difficult problems in rock mechanics and rock engineering. The application of models and methods in computational intelligence is beneficial to the solution of some problems in rock mechanics. Based on some problems in the current applications of artificial neural networks and genetic algorithms to rock mechanics，some advances and research status are briefly discussed and reviewed. The prospects of the applied research in rock mechanics and rock engineering using computational intelligent are also discussed.

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ENGINEERING GEOLOGICAL INVESTIGATION AND ASSESSMENT ON ROCKFALL HAZARD ALONG BASU-LINZHI SECTION OF SOUTH LINE OF SICHUAN-TIBET HIGHWAY

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2004, 23 (09): -1551 doi:
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[PDF 1651 KB] (1386)

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Engineering geological investigation on mountainous hazards along Basu-Linzhi section of the south line of Sichuan-Tibet highway，is conducted，which indicates that rockfall hazard is extremely serious and should be treated as a special kind of hazard with great attentions. By analyzing influence factors of the hazard, an assessment approach is presented, with which 19 rockfall sites are assessed. Countermeasures are suggested according to relatively hazardous levels at a rockfall site.

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TESTING AND ANALYSIS OF GROUTING CURTAIN IN SITE OF QINGJIANG SHUIBUYA HYDROPOWER STATION

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2004, 23 (09): -1558 doi:
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[PDF 229 KB] (1107)

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The engineering geologic condition is complex in Qingjiang Shuibuga Hydropower Station. The concrete slab thickness is 0.6 to 1.2 m and the width is 6 to 8 m，so that the weight of the cover on grout layer is light. The antiseepage standard is quite high，impervious distance is long，and grouting amount is big. According to the practical condition，testing of curtain grouting in site is carried out at region A，which is representative of the whole engineering condition. Deformation is recorded with automatic measuring system. The best arrangement pattern of grouting holes is given based on analysis on test data. 525# Portland cement is adopted and water-cement ratio is divided into five grades of 2∶1，1∶1，0.8∶1，0.6∶1 and 0.5∶1，which are proper for grouting of small water-cement ratio and high pressure. Big upward deformation may occur，and control measures are given to such case.

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CHARACTERISTICS AND APPLICATIONS OF HIGH-PRESSURE GROUTING SOIL NAILING

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2004, 23 (09): -1564 doi:
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[PDF 237 KB] (1165)

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Aiming at the disadvantages of gravity grouting soil nailing，high-pressure grouting soil nailing is introduced in this paper，and its characteristics are discussed. Based on mechanics model of pullout，the transfer mechanism of pullout load of high-pressure grouting soil nailing is discussed. Moreover，the construction process is briefly presented. High-pressure grouting soil nailing has advantages in many aspects，including length of soil nailing，security coefficient of pull strength，bond strength of interface，stability against sliding. Its feasibility is proved in project example.

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CONTACT MODEL BASED ON
AUGMENTED LAGRANGE METHOD AND ITS ENGINEERING APPLICATION

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2004, 23 (09): -1568 doi:
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[PDF 227 KB] (1596)

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A kind of improved contact frictional model on basis of traditional Coulomb Friction model is adopted. Corresponding contact element is also given. The contact algorithm on basis of augmented Lagrange method is introduced and successfully applied to complex contact friction problem. Test example and actual engineering case all show that the algorithm of the model is efficient and computation results agree well with general rules.

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THEORETICAL STUDY OF ROTATING STIFFNESS OF JOINT
IN SHIELD TUNNEL SEGMENTS

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2004, 23 (09): -1574 doi:
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[PDF 231 KB] (1294)

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Based on engineering background of the Shanghai metro tunnel，the variation of joint rotating stiffness is analyzed by establishing a joint mechanics model which can describe any mechanical and deformative status under any group of loading on the joint，including moment，axial force and bolt prestressing force. The study shows that，for given dimension of joint，the rotating stiffness is the function of applied loading，and can be reduced by thinning the segment. This may be adverse to the performance of the loaded joint. But this situation can be improved by changing the position of linking bolt. The mechanical calculation demonstrates that decreasing the engineering cost and improving the performance of the joint can be achieved by adjusting the thickness of segment and the linking bolt position.

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BEHAVIOR STUDY ON DEEPLY-EMBEDDED GRAVITY-FRAME RETAINING STRUCTURE AND ITS APPLICATION

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2004, 23 (09): -1578 doi:
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[PDF 305 KB] (940)

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Deeply-embedded gravity-frame retaining structure，as a new type of retaining structure，combines the features of gravity retaining structure and frame retaining structure，and has the advantages of convenient construction and low cost. Numerical analysis method is used to study the behavior of this retaining structure and its main influence factors，such as the depth，the replacement ratio，and the top position of reinforced zone. It is shown that the moment and displacement of this structure decrease remarkably，so this retaining structure has extensive prospect of application in engineering practice. Finally，the excavation of Yaojiang Building is analyzed，and the theoretical results are close to the measurement data. The reasonability of calculation model in this paper is verified.

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ON COMPUTATION OF OVERBURDEN PRESSURE AND SETTLEMENT FOR LAYERED SOIL CONSIDERING SEDIMENTATION

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2004, 23 (09): -1585 doi:
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[PDF 188 KB] (1058)

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The influence of sedimentation on overburden pressure and settlement of layered soil is studied and the relevant formulas are developed. The results from several numerical examples are analyzed and compared. It is shown that the overburden pressure is varied with depth in a non-linear way when sedimentation is considered, and the influence of sedimentation on settlement of layered soil is increased with load，soil compressibility and thickness of soil layer. The presented work is useful，especially for large strain consolidation analysis of layered soil.