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2005, 24 (01): 0-0 doi:

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2005-01期目录

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NUMERICAL SIMULATION ON SPLITTING FAILURE MODE OF ROCK
UNDER STATIC AND DYNAMIC LOADINGS

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2005, 24 (01): 1-1 doi:

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The program，rock failure process analysis(RFPA)，is developed and the principle of RFPA to simulate the static and dynamic failures of rock are briefly summarized. RFPA is used to study the failure process of rock specimens under static and dynamic loadings. The numerical simulation reproduces the different failure characteristics of rock under static and dynamic loadings，and three typical failure patterns are found under the action of stress wave with different amplitudes. Numerical results indicate that the failure pattern is similar to those under static loading when the amplitude of stress wave is relatively low. With increment of amplitude of stress wave，the other two different failure patterns are also achieved. By contrast to static loading condition，more cracks initiate and propagate under dynamic loading，which cause the damage and fracture of whole rock specimen.

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STUDY ON COALESCENCE MECHANISM OF SPLITTING　FAILURE OF ROCK MASSES WITH INTERMITTENT　JOINTS UNDER COMPRESSION

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2005, 24 (01): 8-8 doi:

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It is of great significance to study the coalescence mechanism of splitting failure of rock masses with intermittent joints under compression. On the basis of the crack isolating theory combined with the near crack line analysis method，the exact elastic stress field near the crack line is analyzed. The relation between the length of plastic zone along the crack line and external load is established by the matching condition of the elastoplastic fields on the boundary. The coalescence stress and the strength properties of rock masses are determined. The solution is a function of the geometry of the crack array. The results show that the coalescence stress and the strength of crack–weakened rock masses depend on the friction coefficient of crack interface，sliding crack spacing，orientation of cracks，and the half-length of crack. Experimental validations are given to illustrate the applicability of the proposed model.

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PARALLEL FINITE ELEMENT METHOD ANALYSIS OF BOLTED ROCK MASS IN UNDERGROUND ENGINEERING

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2005, 24 (01): 13-13 doi:

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There are many problems in analyzing the large-scale geotechnical engineering by finite element method(FEM)：the memory restriction，long computing time and low precision and etc.. For solving these problems，this paper proposes the parallel algorithm of elasto-plastic finite element method(FEM) for bolted rock mass，develops the program in VC++6.0 based on Windows operating system，and carries out the analysis of supporting system of tunnels in the Shuibuya hydropower project on cluster of workstation(COW) successfully. Compared with serial program，the parallel FEM can save computing time and improve computing efficiency.

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PARALLEL ANALYSIS SYSTEM FOR STRUCTURAL　DYNAMIC RESPONSES BASED ON HIGH ACCURACY　DIRECT INTEGRATION METHOD

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2005, 24 (01): 18-18 doi:

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The structural dynamics is applied widely to many fields including geo-engineering，ship building，car industry，etc.. It also demands large-scale numerical calculations. Hardware technologies of supercomputers have achieved internationally advanced level in our country. Generally，supercomputers demand compatibility at the source-code level，so the commercial FEM software usually cannot be adopted directly to domestic Chinese supercomputers，thus puts limitations on applications of supercomputers for engineering fields. To overcome this difficulty，a scheme is presented based on analysis of basic processes of the FEM，using integrated parallel calculation programs for supercomputers and commercial FEM software. During a dynamic response analysis，70 percent of the total time or more is spent on the solution of equations. Therefore，the total time of the dynamic response analysis can be effectively saved on the parallel solution of the equations. The other parts of the dynamic response analysis are serially performed by commercial FEM software. Obviously，the scheme combines strong pre-processing of commercial FEM software with high-speed calculation of supercomputers. The high accuracy direct integration method uses a mass-based matrix-multiplication algorithm and can be easily parallelized. Based on parallel calculation of the high accuracy direct integration method，parallel programs are implemented and some approaches are given in order to save memory. Some existing examples have been tested with the developed technique and the results prove that the algorithm has high speedup and parallel efficiency.

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MULTIPLE-INDEX ASSESSMENT FOR GLOBAL STABILITY OF HIGH-STEEP ROCK SLOPE OF THE THREE GORGES PROJECT PERMANENT SHIPLOCK

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2005, 24 (01): 23-23 doi:

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It is a controversial problem to assess comprehensively the global stability of high-steep rock slope of the Three Gorges Project permanent shiplock. The information on slope stability includes geological data，results of numerical analysis，measuremental data，experiential knowledge，and so on. Therefore，a suitable analytical methodology of system engineering integrating the comprehensive qualitative and quantitative information is needed. A multi-index system and model，which is able to evaluate comprehensively the global stability of high-steep rock slope by using extension theory，is proposed. The qualitative grade and quantitative degree for the global stability of high-steep rock slope by the index system and model can be obtained. The slope stability can be assessed dynamically. Analytic Hierarchy Process method has been used to compute the subjective weights of evaluation indexes. The objective weights can be obtained by calculating the relational degree between evaluation indexes and grades with extension theory. By combination of the views of both the subjective and objective weights，an optimization theory has been used to calculate the weights for index evaluation. The results have shown that for the high-steep rock slope of the Three Gorges Project permanent shiplock，its grade and degree of global stability are 1 and 1.86，respectively. Then the global stability can be ranged between excellent and good. The numerical example has shown that the proposed method is feasible and effective，and the evaluation results are reasonable. In addition，this method can also be used to assess dam health，rock quality，and dam aging.

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EXPERIMENTAL RESEARCH ON THE SOFTENING OF MECHANICAL PROPERTIES OF SATURATED SOFT ROCKS AND APPLICATION

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2005, 24 (01): 33-33 doi:

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Research on softening regularities of mechanical properties of saturated soft rocks and their application is one of the important theoretical and practical problems in geotechnical fields. The mechanical regularities of some typical kinds of soft rocks such as red siltstone，red mudstone，and black carbonaceous mudstone，which are widely distributed in South China，are discussed by designing a series of experiments of interaction between soft rocks and water，and their mechanical parameters are correspondingly tested. By sampling according to a time sequences including natural state and saturated states in different time (1 month，3 monthes，6 monthes，and 12 monthes) of soft rocks，the uniaxial compressive strength，cleave tensile strength，shearing strength，and their varying regularities along with time developing are analyzed. The results show that the mechanical properties mentioned above probably conform to an exponent curve after different saturated time on which the point in 6 month is the critical time for mechanical properties changing from gradually declining to stable state. On the basis of experimental data，by selecting a main section，the BIII2 slope stability in Water Supply Reconstruction Project from Dongjiang to Shenzhen，Guangdong China，is analyzed by nonlinear strength reduction finite element method (FEM). The calculated safety factor is 0.83，which coincides very well with the actual state of the slope. It means that the test results have an important significance for application to engineering and can provide a scientific reference for designing and construction as well as long term safety monitoring and analysis for other similar engineering problems in South China.

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HOLOGRAPHIC FORECAST OF DEFORMATION FIELD OF ROCK UNDER BLASTING BY GREY THEORY

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2005, 24 (01): 39-39 doi:

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It is diffcult to obtain holographic information of deformation field for rock under blasting loading with limit measured information. Grey model GM(1，1) is used to analyze the limit experimental data and to predict the holographically information of dynamic deformation of rock. Compared with experiment results，it is shown that grey model GM(1，1) is feasible and rational for the holographic analysis of rock deformation field under blasting loading.

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EXPERIMENTAL STUDIES AND MICROCOSMIC MECHANICS ANALYSIS ON MARBLE RUPTURE UNDER HIGH CONFINING PRESSURE AND HIGH HYDRAULIC PRESSURE

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2005, 24 (01): 44-44 doi:

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In order to probe the effects of high confining pressure and high hydraulic pressure on the marble characters of strength，deformation，brittle-ductile transition and rupture，and damage degradation，the triaxial compression contrastive tests of marble specimens，which are collected from surrounding rocks of diversion tunnel in Jinping hydroppwer station Grade Ⅱ，are tested respectively under three different states of high hydraulic pressure，and high and low confining pressure. Then the microtest (SEM) is carried out to study its microcosmic character of failure surface under three different pressure cases. The test results indicate that under low confining pressure Moore strength line is linear，whereas nonlinear under high confining pressure. The existing of high hydraulic pressure constrains the development of brittle-ductile transition，reducing the strength and intensifying fission cracking in soften area. Based on the testing analysis of microcosmic digital image，there are smaller fissions，higher density and even distribution under high confining pressure than under low one. Microcosmic damage mechanics of rock cracking under high confining pressure and hydraulic pressure is given. Reliable testing basis is offered to analyze further failure and stability of the noncircular cave surrounding rock under high confining pressure and high hydraulic pressure.

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EXPERIMENTAL RESEARCH ON TROUBLES OF EPB SHIELD CONSTRUCTION IN SANDY SOIL

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2005, 24 (01): 52-52 doi:

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Earth pressure balanced(EPB) shield is one of the most important ways in tunneling. While there are still many troubles including disturbing soil liquefaction，quick sand，‘dry cake’ at work-face due to the output difficulty of soil through screw during tunneling in sandy soil with low plasticity，high water content，and large penetration coefficient. The suitable additives (soapy water and foaming agent) are used to improve construction condition when tunnel passes through sandy strata. In-situ tests were conducted to compare shield driving force with different additives blended in sandy strata. Sandy soil mixed with additives is analyzed by laboratory tests. In addition，influences of two different additives on shield driving force in sandy strata for improving characteristic of sandy strata are compared. Based on the tested data，the effects of two additives in improving plasticity-fluid and capability of retaining water of sandy strata as well as the balance mechanics of shield work-face are discussed thoroughly. The research is valuable in improving characteristics of sandy strata to keep shield work normally while reducing construction deformation，controlling ground settlement efficiently，facilitating soil output through screw，decreasing torque and abrasion of cutter head，and decreasing driving force of jack and avoiding geological disaster.

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PARALLELIZATION OF THE FORCE METHOD BASED ON GENERALIZED INVERSE MATRIX IN THE CLUSTER SYSTEM WITH MPI

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2005, 24 (01): 57-57 doi:

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Generalized inverse matrix(GIM) is a new force method based on the generalized inverse matrix theory，which is an iteration method for solving material nonlinear problems. Unlike the classical force method，GIM does not need to consider the basic structure，so it is also feasible for computer to calculate. This method brings the force method a new light in the computer calculation field. GIM has some natural parallel-calculating characteristics，which are different from the classical substructural algorithm. In GIM，the system control equations are divided into a linear group，which includes the equilibrium equation and the compatibility equation，and into a nonlinear group，which includes the constitutive equation. The iteration procedure starts from a special solution of the equilibrium equation which is achieved by using the GIM theory. The whole iteration procedure can be divided into the global stage and the local stage. In the global stage，the linear group is used，while in the local stage，the nonlinear group must be considered. The calculation can be perform in a parallel way according to the time in the global stage and the space in the local stage. The parallelization process of GIM is present. Several different methods of parallelization are given and compared. The parallelization is considered in the cluster system with message passing interface(MPI). MPI is a kind of parallel environment which is widely used nowadays. Cluster system is a system of many computers linked by high-speed network. The parallelization of GIM in such an environment works well，which proves the parallel-calculating characteristics of GIM to have better performance. The ratio of the time between communication and calculation is an important key during the parallelization. And the parallel program must be compatible with both the hardware and software environment of parallelization.

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PROBABILISTIC ANALYSIS OF EARTHQUAKE-INDUCED LANDSLIDES

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2005, 24 (01): 66-66 doi:

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Earthquake is a random process. Many parameters are uncertain，such as seismic strength，epicenter，and seismological frequency. Based on the existing estimate-criterion，a probabilistic approach to evaluate earthquake-induced landslides is proposed. The probabilistic function，which is used to value the risk of earthquake-induced landslides，is discussed in detail.

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DYNAMIC ANALYSIS OF LONGITUDINAL ASEISMIC RELIABILITY OF UNDERGROUND STRUCTURES

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2005, 24 (01): 71-71 doi:

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The mathematic models of seismic responses used for analyzing submerged tunnels are utilized to study the stochastic seismic responses of underground structures. The principles and methods of computing the impulse-response function for the underground structures with dynamic analysis method are elaborated，and the formulas for evaluating the statistical characteristics of the longitudinal stochastic seismic responses for underground structures are achieved by using principles of Fourier transform and theories of random vibration. With stochastic seismic responses considered as a Poisson process，the formulas for calculating the longitudinal aseismic reliabilities on the basis of the first passage mechanism are established. The Nanjing Changjiang Tunnel is used as an example to compute the square-mean-root responses and the longitudinal aseismic reliabilities under stationary random earthquake loads. A new analysis method proposed in this paper can serve as the theoretical basis for the speculation standards of the stochastic aseismic design for underground structures based on reliability theories.

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WATER-BEARING CHARACTERISTICS AND HYDRO-GEOLOGICAL MODELS OF KARSTIC COLLAPSE COLUMNS IN NORTH CHINA

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2005, 24 (01): 77-77 doi:

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Karstic collapse column is a kind of vertical structure typically formed at Carboniferous-Permian coalfields of north China，and widely distributed in 45 coal mine areas of 20 coalfields. Water inrush from the karstic collapse columns is harmful to mining safety. For simulating them and forecasting water volume with mathmatic models，their properties and controlling mechanisms of water-bearing are studied，and hydro- geological models are set up. The study shows that the water-bearing properties of karstic collapse columns are controlled and influenced by several conditions and factors，such as tectonic movements，groundwater flow conditions，substance，solid and cementation in the columns，as well as confining pressure. All factors promote and restrict each other，so that only in karstic runoff or discharged zones or under water table，there could be danger of water inrush. But if water inrush from them happens unexpectedly，water volume will be destructive，and it is difficult to forecast and prevent. According to viewpoint of systems，karstic collapse column is one kind of media in a mine groundwater system with generalized multiple porous media seepage，and are also special hydro–geological subsystems where karstic groundwater is recharge source，columns are flow pathways，and roadways or working faces are their discharge points. Three kinds of patterns can be classified by interior properties，complete strong water bearing pattern，brim water bearing pattern，and weakly penetrated and runoff pattern. Accordingly，karstic collapse columns are generalized as vertical pipelines，main fractures or vertical cross-stream media，and water barrier or media of aquifer uninfluenced. The mining water volume can be accurately forecast with mathmatic models of mine groundwater systems.

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MODIFIED BP BACK ANALYSIS OF 3D IN-SITU STRESSES

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2005, 24 (01): 83-83 doi:

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Based on regression analysis，an improved method is provided for back propagation (BP) back analysis of in-situ stresses. Linear elastic FEM calculation and linear regression analysis are implemented to determine the general bounds of optimized parameters. Uniform design method is carried out to settle different combinations of factor levels. Training samples are gained by elastoplastic FEM analysis. Levenberg-Marquardt algorithm is applied to achieve better performance during the training process of BP neural networks. Early stopping and regularization are employed to avoid over-fitting problem. When discrete stress values are obtained，neural networks are also used to construct a global stress function with coordinates as parameters.

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NUMERICAL MODELLING METHODS AND APPLICATION IN JOINTED ROCK MASS，PART 2：APPLICATION FOR
ENGINEERING PRACTICE

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2005, 24 (01): 89-89 doi:

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his paper presents the general outline，approach，and procedure of application for numerical modelling methods in rock engineering practices. It is emphasized for numerical analysis to rely on engineering realization and engineering experience when using numerical method to solve engineering problems. An empirical approach is consequently introduced to reasonably estimating the mechanical properties of rock mass. It is also pointed out that the rock mass strengths are significantly underestimated in hydropower engineering practices in China when comparing to the corresponding rock mass properties from mining projects in Canada. Such underestimation is likely to lead to a misunderstanding of numerical modelling results. Additionally，the stress path analysis based on numerical simulations is recommended for the study on stress-induced rock mass problems whereas modelling the behaviour of geological structures is suggested when carrying out numerical investigations under low in-situ stress conditions. All suggestions for these two scenarios are illustrated with application cases of the Itasca program into numerical study of corresponding engineering concerns.

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PRELIMINARY RESEARCH ON COMPOSITE ELEMENT METHOD FOR SEEPAGE PROBLEMS IN DISCONTINUOUS ROCK MASSES

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2005, 24 (01): 97-97 doi:

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The problem of determination for the structural optimal reliability should be considered with union of the structural maintenance and strategy together. In China，there is a big argument，according to the economic development in the past twenty years，it is necessary to increase the safety margin for structural design to a great extent or not. It seems that both sides in this argument have ignored the maintenance strategy. At first，a more advanced and complete multi-objective programming model for the maintenance strategy is introduced. The process of making the model is discussed in detail based on the latest group decision making theory. Meantime，it explained how to choose the structural optimal reliability quantitatively. Some advanced contributions on structural durability，such as data-updating and functional deterioration of reinforced concrete elements，can be integrated in the present model. Based on dynamic programming，a practical and simple algorithm is given. As an example，the analytical results show that the reliability is not sensitive to the overall income during the structural service-life.

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CALCULATION OF INTERNAL FORCE OF EMBEDED ANTI–SLIDE
PILE IN HIGH ROCK SLOPE

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2005, 24 (01): 105-105 doi:

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According to the location and characteristics of embeded anti-slide pile in high rock slope，the mechanical behaviour of non-anchored section of pile is analyzed. Both thrust behind pile and resistance in the front of pile is rationally simplified as rectangulaly and triangulaly distributed loads，respectively. Based on this mechanical model，the calculation procedure of internal force of embeded anti-slide pile is given. Taking the section K101+240 of Beijing-zhuhai Expressway in the north of Guangdong province as an example，the calculation results of embeded and cantilever anti-slide piles are carulated. The results show that the distribution of internal force of embeded anti-slide pile is relatively reasonable，and the length of anchorage section is properly shorten.

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RISK ANALYSIS OF ROCK TUNNEL ENGINEERING

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2005, 24 (01): 110-110 doi:

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The risks of rock tunnel engineering are classified based on the data of accidents in rock tunnel of Japan and other countries over the past 20 years. The application of risk analysis to rock tunnel engineering is discussed. Finally，a practical case study of risk analysis is presented.

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APPLICATION OF PRESSURE-RELIEF SUPPORT TECHNIQUE
TO COAL ROADWAY

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2005, 24 (01): 116-116 doi:

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According to the practical case of Fenghuangshan Mine，the destruction reason of support for previous roadway is analyzed. Combining the maintenance principle of pressure relief and support，the principle of pressure–relief support is interpreted with the consideration of wall rock creeping and pressure relief. Simultaneously，it is presented how to determine the parameters of pressure–relief support. The pressure–relief support is successfully applied to the upper return airway of working face 2322 of Fenghuangshan Mine. Compared with previous support，pressure relief support is of simple production process with lower maintenance costs，and it is very convenient to apply with significant social and economic benefits.

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INTERACTION BETWEEN TUNNEL ENGINEERING AND WATER ENVIRONMENT

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2005, 24 (01): 121-121 doi:

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In tunnel engineering，the strengthening water drainage as a design principle can not meet the demand of water environmental protection at present. However，it is difficult for the tunnel to endure huge water pressure when underground water is blocked up fully. By establishing interaction chain between tunnel engineering and water environment，the sluicing quantity of tunnel hole before lining is estimated with non–stable flow method. The scope，bulk，and deep draw-down of dewatering cone in aquifer above the hole are predicted. The permissible dewatering of tunnel lining for restoration of water environment is determined based on equilibrium equation of surface water，and the water pressure endured by tunnel lining is calculated based on discount coefficient method. In order to prevent and control water environmental hazard of ground above tunnel and sluicing hazard in tunnel a principle of ‘water environmental balance’with choking up underground water is summed up as a leading principle in tunnel design. Finally，the Yuanliangshan tunnel of Yu(Chongqing)–Huai(Huaihua) railway was analyzed as a calculating example.

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DIFFERENTIATION AND GRADE CRITERION OF STRONG
SWELLING SOFT ROCK

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2005, 24 (01): 128-128 doi:

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Presently，the researches for differentiation and grade criterion of intense swelling soft rock are in primary phase with important application in practical engineering. On the basis of previous achievement，this paper presents the most essential matter of soft rock with strong swelling characteristics by combining engineering practice，field and laboratory experimentation results. The reason of strong swelling characteristics is that the soft rock contains plentiful high hydrophilicity clay mineral，such as illite / montmorillonite mixed-layer mineral. At the same time，the differentiation and grade criterion of strong swelling soft rock by combining physics，chemistry and mechanical index are fully discussed and the results prove to be successfully in the engineering practices.

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NEW GEOMETRIC INTERPOLATION METHOD BASED ON
VORONOI DIAGRAM AND THE COMPARISON WITH
TRADITIONAL ALGEBRAIC METHOD

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2005, 24 (01): 133-133 doi:

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The natural neighbour interpolation based on Voronoi diagram is the mathematical base of natural element method (NEM). It is a new geometric interpolation method and to be constructed by a special procedure different from traditional method，meanwhile it does have some advantages. The Sibson interpolation and non-Sibnian interpolation based on natural neighbour relation are introduced，then the comparison with FEM and EFG interpolation about discrete scheme，mesh property，calculation cost and so on is conducted.

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NON-LINEAR MECHANICAL ANALYSIS OF SHAFT LINING IN STRATUM SETTLEMENT RESULTED FROM WATER DRAINAGE

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2005, 24 (01): 139-139 doi:

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Based on the theory of pile foundation，by considering the relative displacement in shaft lining and strata，the shearing displacement method is used to obtain the additional forces and the axial stress in shaft lining，and comparison of that the results with finite element method is conducted. The results can provide a theoretical basis for design.

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SUPPORT VECTOR MACHINE MODEL IN SLOPE STABILITY EVALUATION

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2005, 24 (01): 144-144 doi:

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Based on the main factors with important influence on slope stability，the support vector machine (SVM) model of slope evaluation is established. The nonlinear relation between slope stability and influencing factors is obtained from the finite empirical data by SVM model，and the model is applied to the practical engineering. Based on the results，it is not effective enough for SVM model of linear kernel function to find the nonlinear mapping between classification of slope stability and influencing factors，but the classifying device based on neural kernel functions and radial based function (RBF) kernel can correctly determine the classification of slope stability.

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RELIABILITY EVALUATION OF SLOPE ENGINEERING
BY SUPPORT VECTOR MACHINE

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2005, 24 (01): 149-149 doi:

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Based on the problems existing in reliability analysis of slope engineering，complicated geological conditions of slope engineering，physicomechanical parameters of rock and soil，and uncertainty of mechanical mechanism，support vector machines(SVM) method is presented and applied to evaluate the reliability of slope engineering. The results show that the SVM method has advantages in its simple structure，excellent capability in studying and good application prospects.

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GENERATION，DEVELOPMENT AND PROSPECT OF GEOLOGICAL ENGINEERING

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2005, 24 (01): 154-154 doi:

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A new science discipline-geological engineering has been formed based on the development of engineering geology and rock mechanics. From engineering geology to geological engineering，there is a great advance forward which changes the face of the nature. The generation of geological engineering undoubtedly advance the development of relative subjects such as geology，rock mechanics，environment science and etc.. How to harmonize the relationship between human engineering activity and the nature is the focus problem of the world. Geological engineering plays a more important role in the future. Geological engineering along with its history，basic theory，technique and methodology，etc. are discussed. Besides，the development trend and prospect of geological engineering are also reflected here.

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NEW APPARATUS FOR MEASUREMENT OF STRESS EFFECT ON PERMEABILITY OF UNSATURATED SOIL

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2005, 24 (01): 160-160 doi:

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An introduction to a new apparatus，which can measure the effect of stress state on permeability of unsaturated soil，is performed. The experimental data measured using the new apparatus are checked by the results obtained from other methods. It is shown by the comparison between the experimental data measured using this new apparatus and those from other methods that this new apparatus is suitable to measure the effect of stress state on permeability of unsaturated soil with high accuracy.

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ANALYSIS AND TREATMENT OF A QUALITY PROBLEM OF COMPOSITE FOUNDATION OF CFG PILES FOR BUILDING 4 IN XIZHAOSI RESIDENTIAL AREA

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2005, 24 (01): 163-163 doi:

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Data obtained from composite foundation monitoring showed that the allowable bearing load of some cement flyash gravel(CFG) piles for building No.4 in Xizhaosi residential area did not meet the requirements of engineering design. After re-exploration and careful analysis，it was found that the sand soil under the bottom of the pile and around the pile was disturbed during the construction of CFG piles. This paper aims at reminding engineers and technicians of elaborate design and construction of CFG pile to ensure quality in composite foundation design and construction.

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ANALYTICAL SOLUTION FOR MODEL OF PILE HAMMER IMPACT

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2005, 24 (01): 171-171 doi:

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The drivability study of piling requires modeling of the hammer impact to calculate the input force wave at the pile head. This force wave can be computed numerically or by simple analytical solutions. Analytical solutions are presented for hammer impact considering a model which uses lumped mass for the ram and anvil，a spring and a dashpot for the anvil cushion，and another spring for the cap cushion on the top of a pile. The pile is modeled as a dashpot. The solutions account for the separation of the anvil mass from the pile cap cushion as well as the separation of the ram mass from the anvil cushion. The developed solutions are used to perform a parametric study to show the influence of the pile cushion and the mass ratio of pile cap to pile hammer on the maximum force transmitted to the pile head. The parameters of pile cap cushion are achieved by laboratory static test. Force-time responses derived from the analytical model are compared with field data，which indicate well consistent with each other.

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ON SLOPE STABILITY ANALYSIS BY IMBALANCE THRUST
FORCE METHOD

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2005, 24 (01): 177-177 doi:

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Imbalance thrust force method (ITFM) has been used widely in the fields of industry，civil and railway in China. When the slip face is circle，the precision of ITFM is equivalent to that of rigorous method such as Morgenstern-Price method. But because the method unreasonably assums that the orientation of interslice resultant force is parallel to slice bases，for non-circle slips，the error of safety factor obtained from ITFM is up to several decades percent or more，which leads to hidden trouble inevitably. So，focusing on the non-circle slips，the error by ITFM in most kinds of conditions is analyzed thoroughly，and a few conditions with small error are obtained. For the analysis of slope stability，it is suggested that for non-circle slips，it is better not to use ITFM alone，but to adopt two or more methods，instead.