This paper reviews and analyzes the cases of failure arch dams caused by asymmetric dam foundation. Based on geomechanics model tests and three-dimensional finite element simulation，the influences of asymmetric foundation of Jinping high arch dam on integrity stability and its reinforcing measures are discussed. The physical experiment and numerical simulation show that tensile stresses at dam heel are too high，and emerge in downstream surface. The stress status of dam is asymmetric so that the deformation of the left abutment is larger than that of the right abutment，and leads to cater-cornered cracks to propagate along the downstream surface. The overload capacity of this arch dam is limited. By employing large concrete buttress and anchorages，the reinforcement measures are proposed for the stability of this arch dam.

The nonlinear elastic hysteric behavior，which is off the Hooke¢s law and caused by the presence of structural defects in rock，such as microcracks and grain boundaries，universally exists in the measurement of stress-strain relation. The instantaneous elastic moluli of rocks in both loading stage and unloading stage vary with stain，which results in lopsided bowknot shape of instantaneous elastic modulus. Hefei sandstone，Zigong feldspar sandstone and Dali marble，saturated in 3 types of fluids with different viscosity coefficients，are tested with various frequencies by cyclic loading experiments. The angle between the loading modulus and the unloading modulus of bowknot shape is suggested to measure hysteresis of rocks，and to compare it with dissipative angle which measures hysteresis originally. Both bowknot angle and dissipative angle enhance as the area of hysteresis loop increases，and attenuation enhances as viscosity coefficient of pore fluid increases. With both the bowknot angle and dissipative angle increasing，modulus increases，and dispersion of modulus enhances as frequency increases. The variety of bowknot angle and dissipative angle with viscosity coefficient of pore fluid and cyclic loading frequency is consistent with the results of other experiments. The conclusion is drawn that the bowknot angle and dissipative angle are equivalent in measuring hysteresis of rock but are not in numerical value. The physical mechanism and significance of definition of hysteresis are discussed.

The formation of Kanto Plain around Tokyo Bay，Japan，is a sediment in the oceanic environment through several hundred thousand years or even million years¢ geological activity. Under this geological activity，Ocean Plankton was transformed into high quality water soluble natural gas and medicine iodine. Since 1930s，there were gas production activities near Tokyo. Large-scale production of gas and iodine in Kujyukuri area started from 1956. Production was conducted through withdrawal of groundwater from the depth of 500 to 2 000 m. Land subsidence was found since 1960s and large-scale land subsidence surveying was started in 1969. During past 35 years，the maximum accumulated subsidence was 0.85 m and subsided area was 800 km2. The coastal line of Kujyukuri backed off 20–50 m from its position in 1960s. In 2002，there is about 20 mm subsidence per year yet. Finally this paper describes South Kanto gas field and subsidence in Boso area. Discussion is made on the possible countermeasures to mitigate the subsidence：(1) recharge of some percentage of extracted volume of groundwater；(2) reduction of the withdrawal volume of groundwater. Through analysis of the structure of Kanto Geologic Basin，it is pointed out that reduction of the withdrawal volume of groundwater is more economic and effective than the other methods.

Two major faults are located in the heel and toe of Guangzhao gravity dam with height of 200 m. A nonlinear 3D numerical simulation is conducted on a typical monolith to analyze the impact of faults on stress-deformation status of the gravity dam and stability of the abutment. Simultaneously，the impact on the gravity dam，which is caused by the increase of fault deformation modulus induced by the variation of confining pressure after the dam completion，is also analyzed. Sensitivity analysis of faults is conducted；safety of abutment impacted by faults is calculated by strength reservation method；and different reinforcement methods on the two faults are simulated respectively. The results show that the F2 fault located near the dam toe makes a great impact on stress status of the dam，and it is a major factor to control stability of the dam. Not only is the stability increase，but also the stress status is improved after consolidation grouting. It is suggested that F1 fault near the heel should not be excavated deeply. The increase of fault deformation modulus，which is induced by the variation of confining pressure after the dam completion，has an advantageous impact on the stress status of dam.

The practical blasting engineering is considered as rock mass engineering，and the general characteristics of rock mass blasting are discussed. There are various discontinuous joints and fissures in rock mass which have statistical characteristics，so the distribution parameter can be measured. The damage parameter is defined as the ratio of the area of fragmentation after blasting divided by the area of all sections. The definition meets the requirement that the damage of intact rock is 0 and is 1 after blasting. The rock fragmentation has fractal character and has relation between damage parameter and fractal dimension. So the evolvement equation can be established. The numerical calculation of the statistical damage model indicates that this model is clear in theory and applicable in practical engineering.

The stress field and acoustic emission(AE) field of two kinds of discontinuous jointed faults，en-echelon faults and collinear disconnected faults，are numerically simulated using rock failure process analysis code (RFPA2D). The thermal infrared radiation(TIR) from the loaded rock surface of modeled jointed faults is detected by a TIR imager，and the experimental boundary conditions are similar to that of numerical simulation. The detected TIR is analyzed and compared with the numerical test results of AE. It shows that the spatio-temporal characteristics of TIR radiation and AE are similar. Besides，by comparing the TIR images with the stress field and visible light photos，it is revealed that the TIR from different cracks，such as the wing crack and shear crack，present different characteristics. The physico-mechanical mechanism of the TIR abnormal and difference are discussed.

The mining rate affects the results of stress distribution，deformation and failure process in surrounding rocks in mechanized top-caving mining face. The rate effect can be summarized as follows：(1) the completion of stress transition in surrounding rock under different mining rates；(2) the variation of loading and unloading rate in process of different cutting depths in unit period of time；(3) the development of deformation and stress distribution in rock due to creep behavior. Based on the mining state in Xieqiao Colliery，numerical investigation is carried out to reveal the fact that the reduced stress zone around the mining face decreases with the increase of mining rate. Consequently，the failure zone decreases，and the peak stress locates nearer the mining face while the stress value increases. Since the deformation period becomes shorter，as a result，the displacement reduces. The study points out that appropriately increasing the mining rate of mechanized top caving mining face will benefit the mining face management and safe production.

Engineering geomechanics is a subject aiming at investigating generalized deformation and failure processes of geological body for engineering problems. Due to geological body inherent characteristics of discontinuity，inhomogeneity，coupled fluid-solid and unknown initial state，key scientific issues in engineering geomechanics are how to judge current state of geological body，how to describe mechanical properties of geological body，and how to simulate the evolution from continuous to discontinuous failure process. Researches in the area of engineering geomechanics should take geology as the foundation，take mechanics as the analytical tool，and its aim should face engineering. The engineering problems to be solved include investigating the geometrical and mechanical properties of geological body，developing the analytical method for geological body stability，and providing the design basis for geological engineering as well as the prediction and forecast scheme. Whether model experiments or simulation results of experiment can answer engineering questions is determined by the extent to identification of geological conditions. But experimental studies can be recognized as a powerful tool to verify the results of numerical simulation；and geological investigation and spot survey are indispensable parts in engineering geomechanics. The mechanical classification of geological body embodies the underlying role of geology，and is able to quantitatively represent the geological environments. The construction of mechanical models，which meets engineering requirement，needs to consider rock masses with discontinuity，rock and soil aggregates as well as the interaction between flow in fractured rock and rock masses. The extraction of measurement parameters，development of approaches to obtain these parameters，and research on relevant test devices require the participation of geomechanics. While present mechanical models are improved or new models are developed，more attention should be paid to the verification and application of new methods.

FEM is a numerical simulation method commonly used in geotechnical engineering. But for the large-scale problem with complex strata and large-scale region in geotechnical engineering，the calculation precision is not good enough. Refinement of finite element mesh causes element number increase greatly；and single PC computing capacity will be insufficient to accomplish the huge computing task. Based on the domain decomposition and precondition conjugate gradient methods，a ParallelGeoFEM3D program is developed and implemented on cow cluster of workstation(COW). The construction sequence of the tail-tunnel excavation of Shuibuya Project is simulated with 100×104 elements and 20 excavation steps successfully showing the ParallelGeoFEM3Dcan analyze construction options fast and accurately.

The mechanical model of key strata supported by coal pillar is set up according to the layout of coal pillars in the coalface of short wall mining. With the help of analysis of elasticity and viscoelasticity of enforce and deformation of key strata using different design parameters in different working face，the theoretical formulas of ground subsidence of elastic medium key strata and the dependence of the deformation on time of viscoelastic medium key strata are obtained. The parameter ranges of the short wall mining under buildings are proposed；and the influence of key strata on the deformation with time for different parameters are evaluated. The model provides theoretical basis for the design of short wall mining under buildings，water bodies and railways，and for the prediction of ground subsidence.

The J-typed ventilation，based on the U-typed ventilation，is specially designed with one inflow and two outflows for draining gas better. It includes an extra tunnel of gas drainage called as tail tunnel，which is not built by tunnel driving but by a technique of small-section road retained along next goaf. To illustrate the advantage of such ventilation，this paper takes the ventilation and methane drainage of the 5201 mechanized top coal caving face and gob of Lu¢an Wangzhuang mine as examples. Firstly，with the RFPA¢2000 software and the volume control technique，the regionalized property of bearing pressure on the gob area is obtained as a guide of seepage modeling of the gob area. According to the regionalized property and the relationship between the bearing pressure and overbroken rock filling percentage，the seepage models of J-typed and U-typed gob areas are set up；and the gas flow characteristics and methane density distribution inside are calculated. The simulation results show that，one source and two affluxes are found for the air flow of J-typed gob and just at the beginning of entrance the gob inflow air is obviously bi-divided. One subflow slowly and tortuously moves towards the lateral wall or exit of the tail tunnel. The other gob subflow runs over the partial gob area in the neighborhood of the work face，and gets to the entrance of the air-return tunnel. Quite differently，the U-typed ventilation shows the arc distribution of air flow around the gob near the work face，and with the depth into the gob area increasing，the velocity of flow gradually drops. The thickness distribution of gob methane obviously changes from one place to the other. Generally speaking，in many a gob part，the J-typed methane thickness is much less than the U-typed one，or in other words，by using a J-typed ventilation the methane concentration at certain places of gob and face can get pretty improved.

The failure progress of geological material is a key scientific problem in the engineering of geological hazard and control，and is also a frontal problem in mechanics. The continuum-based discrete element method (CDEM) is a numerical method to research this problem. According to the method to solve eigenvalues of matrix，the analytical expressions of the spring stiffness in the discrete element from the stiffness matrix of the three-dimensional finite element is deduced；and the rules how to choose the spring in the discrete element under different conditions are presented. The spring properties of the discrete element in the 8-node solid isoparametric element is investigated；the expressions of the stiffness and directions of the spring between common edge particles，between common diagonal of face particles and between common diagonal of cubic particles are deduced；and the figures about the relation between the stiffness and directions of spring and Poisson ratio are given. Finally，the CDEM is compared with both Gusev model and two-dimensional nets model. When the Poisson′s ratio is 0.25，the CDEM model is consistent with two-dimensional nets model in plane stress problem. And when the Poisson′s ratio is 1/3，the CDEM model is consistent with two-dimensional nets model in plane strain problem. In block interior，the CDEM model is consistent with Gusev model. The CDEM model can simulate boundary element which Gusev model and two-dimensional can′t，and is proved to be more universal than the other models.

A numerical study of convection heat transfer between air and porous media in ventilated embankment using nonlocal thermal equilibrium model is presented，and the optimal phase of opening and closing of ventilated ducts is obtained，which provides theoretic foundation for the design of ventilated embankment.

Deep rock is located in definite geological environment. Therefore，the conditions of temperature and pressure have especially important influence on the mechanical properties. Based on the conditions of temperature and pressure，the geothermic character and ground pressure of the deep formations of Carbonic and Triassic sandstone in Tahe oil field of Talimu basin are researched. The effects of different temperatures and pressures under deep conditions on mechanical property of sandstone are studied by using triaxial rock mechanics experimental system；and the relative relationships between the mechanical properties of sandstone and temperature or confining pressure are established. It is shown that the mechanical properties of sandstone are closely related to its temperature and effective confining pressure. The stiffness and strength of the sandstone decrease with temperature increasing；and the residual strength after rock failure also reduces when temperature increases. The stiffness and strength of sandstone increase with confining pressures increasing and the failure mechanism of the rock transforms with the increase of confining pressure.

Planning and design of underground engineerings，such as underground mines，underground powerhouses，nuclear waste repositories，subway systems，amongst others，involves a process of complex spatial n-dimensional data integration utilizing information from field exploration(geology，geophysics，geochemistry，geostatistics，groundwater，and rock mass characteristics)，engineering(excavation placement，geometry，stress and strain) and operations(scheduling and costs). As new logging and monitoring technologies are being developed，the amount and complexity of data becomes overwhelming and，in the past，decisions are often made based on only a small part of the available data. Recently，Laurentian University in Canada opened a state-of-the-art Virtual Reality Collaboration Laboratory(VRCL)，a unique facility offering an exceptional data interpretation environment for sub-surface engineering planning and design. This facility，designed to meet the needs of the mineral exploration and mining industries，offers a team interpretation environment for earth modeling applications. The main benefit for multi-disciplinary teams is the speed with which complex subsurface models can be interpreted，explained，and evaluated. Through examples from site characterization for deep underground mines and mine planning and design，this paper demonstrates how value(project-wide data integration，improved 3D understanding，reduced engineering rework，project team collaboration) can be added to the geotechnical planning and design process of underground engineerings by utilizing this unique tool to comprehend spatial relationships of data. The paper is built on our experiences involving project-wide data integration，mine design validation，rock support planning and design，and visualization of geomechanics design criteria developed at the Geomechanics Research Center of Laurentian University in Canada. It has been proven through practical application of the VRCL technology that it is not the quantity or quality of the data，but rather the quality of the decision that is made based on the data，that renders the VRCL an invaluable resource for the industry. Recently，the first stage of a global network – Northern Advanced Visualization Network—is being built to link virtual reality centers in northern Ontario in Canada，for expertise sharing and tele-decision-making.

Xiaowan Hydropower Project is located on Lancang River of Yunnan Province in China. The dam is 292 m high，13 m wide at the top，about 69 m wide at the base and has a maximum capacity of electrical generation of 4 200 MW. The sixth slope is near the dam on the left bank. When digging a road，part of the sixth slope began to slide. For security of the project，countermeasures have to be taken. So it is necessary to find the potential instable zone，which is of the most concern. Through investigation，it is known that landslide happens along original joints and faults，and it is speculated that the next landslide will continue to happen along them. By analyzing the location of joints and faults and the deformation failure mechanism of landslide，the possible unstable zone is deduced. Based on plentiful investigation data and the test results，a numerical model of the sixth slope is built with ANSYS，and the joints and faults are modeled with low strength materials. Results show that the stress and strain of the slope change after landslide. By comparing the tracks and curves of the stress and strain before and after slides，the potential instabe zone of the slope is identified；and countermeasures are designed. The study shows that the identification of the zone by both methods is consistent and this approach is practicable and the result is believable.

An artifact is usually regarded as a measure error，but the boundary artifact is an exception，which occurs in the interface between two different media. As a kind of systematic errors caused by reconstruction algorithm of CT images，the boundary artifact contains some information of the sample size. Based on conventional back-projection reconstruction algorithm of CT image，the mechanism of CT boundary artifacts is analyzed. The study shows that the sample boundary is in correspondence with the position of CT boundary artifact maximum and the study on boundary artifact is beneficial to correctly judge the position of sample in CT image and evaluate the geometrical dimension of sample.

Triaxial creep experiments of slates under different confining and axial pressures are done through the XTR01 electric-fluid servo-compression machine，which are taken from the West Route of South-to-North Water Transfer Project. During the creep process，decay creep and steady creep appear under different axial pressures，which can be described through the viscoelasto-plastic model. The model comprises three parts：Newton¢s model，Bingham¢s model and viscoplastic model. The constitutive equation of the model is established and the characters are analyzed. The creep parameters are fitted through the experiment data. The creep rate of the slates are also fitted. The results show that the creep rate decreases gradually until it reaches the steady rate. All these results can be used to analyze the deformation of the slates later.

The mechanism of the fracture coalescence between two flaws is studied under uniaxial dynamic loading. The specimens made of sandstone-like modeling material contain two pre-existing flaws with different geometry distribution including echelon and co-planar arrangement pattern. Through the comparisons of the fracture propagation length，coalescence mode of the fractures and strength increase of the pre-cracked specimens under static and dynamic loading，the dynamic response of the fracture coalescence is found different from static one under different geometric setting of the flaws. Furthermore，the inertia effect of the fracture propagation is revealed under dynamic loading，the growth of the wing fracture and secondary co-planar fracture tends to the original propagation direction；and the immediate coalescence is taken place easily between two pre-existing flaws. But the fracture coalescence path is winding under static loading，which is different from dynamic loading. So，the inertia effect of the fracture propagation is regarded as the main cause of the strength increase of the brittle material under slow to medium strain rate. In virtue of the explanation，the second cause of the mode II shear fracture under earthquake is released.

The linear displacement discontinuity model is derived from elastic displacement functions of wave，and then a nonlinear displacement discontinuity model is established by introducing the equivalent displacement hypothesis. Based on the established model，the analytic resolution of transmitted and reflected coefficients is obtained when the normal incident P-wave propagates to the nonlinear normal deformative joint. The effects of parameters such as initial joint stiffness，quantitative ratio of joint closure to allowable joint closure and incident frequency of wave on transmitted and reflected coefficients are investigated. By comparison with the published numerical results，it is found that the analytic results agree well with the numerical calculations.

3D deformable distinct element method (3D DEM) is an efficient numerical method for simulation of mechanical behaviors of discontinuous media. It is especially suitable for analyzing problems of nonlinear，large deformation and dynamic systems due to the explicit finite-difference scheme and the automatic contact detection skill. Herein，the principles and features of the 3D deformable distinct element method are first summarized. Then，an analysis of stability against sliding of an arch dam-abutment system is performed by 3D DEM. Two methods，i.e. overloading method and strength reduction method are used to determine the safety factor against sliding of the system. Some conclusions are drawn as follows：(1) the rock abutment will not slide under even large overloads due to self-locking effect for this specific case，but the dam concrete will yield to compression failure at the overload factor of 4.0；(2) the strength reduction method shows that the left abutment rock reaches failure，which causes the dam collapse under the designed upstream water and seepage pressure when the coefficient of reduction arrives at 3.5. Based on the explicit finite-difference scheme of the 3DEC，the dam collapse process is emulated very well.

The study of the instability of quasi-brittle materials under the action of a non-stiff loading system is helpful to forecast the unstable failure of materials or structures and to extrapolate the intensity of catastrophic failures. Firstly，the cusp catastrophe model established by Tang and Xu for rock unstable failure process is generalized in this paper by adopting a general form of material constitutive equation. The condition for the outbreak of instability，the total deformation and the energy release of the material and the loading system，and the deformation jump of the material in the catastrophe process are obtained. It is found that the catastrophe in the unstable failure of quasi-brittle materials and its intensity are determined completely by the material properties and the stiffness of the loading system and the catastrophe intensity is independent of the total deformation. Secondly，two types of material constitutive relationships based on the Weibull distribution and the lognormal distribution respectively are introduced into the generalized cusp model，from which two factors affecting the instability are founded further. One is the initial ratio of the stiffness of the loading system to the material stiffness. The instability takes place easier and its features become prominent as the ratio decreases. The other is the material homogeneity. As the homogeneity decreases from that of the totally homogeneous material，the total system deformation decreases and the instability is aggravated. But for a real loading system，which has a non-zero stiffness，as the homogeneity drops below a value，the total system deformation increases slightly and the instability weakens. Lastly，the method to find the relationship between the parameters in different types of constitutive equations of a material by means of the results from the generalized model is proposed as well. The relationships between the homogeneity indices of the two constitutive equations discussed in this paper are obtained by this method. These relationships are in excellent agreement with each other.

Numerical simulation and experimental testing are used to study wave propagation characteristics in grouted rock bolt. Both show that the waves which propagate in grouted rock bolt are guided waves and different frequencies have different wave velocities and attenuation characteristics. There is an optimum excitation signal which has smallest attenuation in the grouted structure and can propagate for longest distance in the grouted rock bolt. The optimum excitation signal for our experimental grouted structure which makes clearest end reflection is firstly found by numerical simulations. And then the experimental set-up and transducers are made and the experiment testing results agree well with the numerical simulation showing that the optimum excitation signal can increase greatly the penetration range of ultrasonic wave greatly.

Technique of geological prediction ahead is one of the important parts in tunnel informational construction，especially for important projects，it is very significant with accurate and instantaneous geological prediction. Many have been studied from different angles with new techniques and methods. Lots of methods have been acquired such as ground penetrating radar(GPR) and tunnel seismic prediction(TSP). However，engineers cannot obtain satisfied results from single prediction method. Based on this background，geological prediction techniques are discussed and studied. And then，according to ground geologic survey，GPR and TSP，a synthetic geologic prediction method is put forward. The problems such as inaccurate and even improper geological prediction，which were found during geological prediction，are discussed and the merits and weaknesses of the three main methods are analyzed. The synthetic prediction method is discussed in detail. And then the realization process is put forward. Finally，the application of the synthetic geological prediction method to the geological prediction ahead of Guangrenling tunnel is illustrated. Two faults are forecasted successfully and the precision reaches 95%.

Breakage is an important factor to influence wetting deformation of coarse-grained materials；and farther study is necessary. The wetting triaxial tests under various confining pressures and wetting stress levels are carried out on a coarse-grained material with a new stress-control triaxial apparatus；and the grain grading test is done with the samples before and after wetting. According to the tests，the cause of grain breakage due to wetting is explained；and the wetting deformation and grain breakage value expressed by Hardin index are obtained. The test results indicate that the wetting deformation is related to confining pressures and wetting stress levels；the wetting induces the grain breakage；and the wetting grain breakage has obvious influence upon the grain size distribution curve. The difference of grain size distribution curve before and after wetting is like a hump；and the maximum value is located at about the grain diameter of 25% of the grain size distribution curve . The grain breakage caused by the wetting reduce the coefficient of curvature；the coefficient of uniformity and the special grain diameter of 60% of the grain size distribution curve and the grain breakage value becomes greater with the increase of confining pressure and wetting stress level. The wetting deformation has close correlation with the wetting grain breakage；and the axial wetting deformation is linear to the grain breakage approximately. It is found that the wetting deformation behaviour can be explained from the viewpoint of the wetting grain breakage.

A classical elastoplastic constitutive model is generally defined in a 2D or 3D coaxial stress space and has a postulate of normal plastic flow rule. As a result，the classical elastoplastic constitutive relation implicates an inevitable limitation that directions for principal stress and that for principal plastic rate of deformation are always coaxial. Therefore，a non-coaxial constitutive model is indispensable in order to offer an insight into the behaviour of rocks and soils. In this paper，a non-coaxial plastic strain rate is defined；and a framework of non-coaxial model is built based on 3D coaxial stress space. The analysis finds that the classical non-coaxial stress rate，proposed by J. W. Rundnicki and J. R. Rice，is only built on the basis of 2D coaxial stress space but invalid in multi-dimensional stress space since the effect of the third stress invariant on non-coaxiality is ignored. The stress-probe test in multi-dimensional stress space shows that an incremental nonlinear response can almost be observed as the rotation of principal stresses，whilst no non-coaxial plastic strain exists in a true triaxial state. The probe results exhibit a coincident constitutive response with a lot of experimental observations.

The physicochemical soft rock is a rock containing a great amount of clay minerals. Under engineering disturbance conditions，it is easy to swell and shrink by wetting and drying and to reduce rapidly its engineering properties. It is one of the biggest rock mechanics problems in geotechnical engineering. Because the physico- chemical soft rock is of such physical and mechanical properties as hydrate swelling，strength dropping down and softening break etc.；it has brought a great influence on the stability of many important projects. Based on the analysis of the composition of the physicochemical soft rock，the microstructure shape change and swell-shrink mechanism in the drying-wetting process of the clay minerals，the swell-shrink geometrical model and its corresponding equation of the tetrahedral microstructure unit consisting of hard sand and clay minerals tactic strata in the physicochemical soft rock are put forward. This equation offers a theoretical foundation for the quantitative research of the swell-shrink property of soft rock. But it is necessary to do further study in the composition，mineral microstructure and mineral swell-shrink parameters etc. for its application in practice.

Rock-soil aggregate is a special kind of engineering geological body，its mechanical characters are very complicated. It has huge influence on engineering projects. For it has very complicated physico-mechanical properties and the collection of its samples is very difficult，the study has not been sufficient so far. In order to make more study on the distortion and destruction characters of the rock-soil aggregate，six test sites on the right bank of Longpan in Tiger-leaping Gorge reservoir area are selected. In these six test sites，six horizontal push-shear in-situ tests were done，which include three non-water immersion tests and three water immersion tests，and some significant results were obtained. Through these in-situ tests，the strength characteristics and the complete stress-strain curves under various states were obtained. At the same time，by analyzing the group of block size and the three-dimensional sliding face，the mechanism of distortion and destruction of rock-soil is discussed to explain why the friction angle is on the high side in such kind of special geological body，and the conception of the average sliding surface which is used in calculating the strength parameters and the conception of the key diameter which is very important in determining the value of the cohesion are put forward. At the end，a reasonable reference value on the strength parameters of rock-soil aggregate in the study area is proposed to establish the foundation of the 3D slope stability analysis.

According to the test data of the thermal capacity and thermal conductivity of large amounts of soil samples in Nanjing district，the relationship between soil thermal properties and moisture content and pore-solid ratio are analyzed. The soils used are classified as clay loam and sandy loam. At the same time，elements which have effects on the thermal capacity and thermal conductivity are analyzed. Finally，empirical formulas of thermal capacity and thermal conductivity are proposed on the basis of moisture content and pore-solid ratio.

With the expressway tunnel tending to be long and wide，its stability is becoming the key problem for the design and construction. The Hejiagou expressway tunnel，which is double-lane tunnel with separate up and down lines，is taken as an example. The mechanical response of excavation and support is studied using the three-dimensional fast Lagrangian analysis of continua(FLAC3D) method. The numerical simulation reveals the distribution characteristics of displacement and stress for the underground structure under the condition of dynamic step excavation and support. The distribution of plastic zone is graphically presented for the different construction stages and its mechanism is also discussed in detail. The obtained conclusions offer a guideline for the design and construction of tunnels in rocks and soils.

Construction of tunnels in urban area requires assessment of the effect of tunneling on the stability and integrity of existing pile foundations. This paper discusses the bearing capacity of pile-foundation under the effect of construction of metro tunnels adjacent to pile foundations based on the engineering background of the construction of No. 2 Line of Guangzhou Metro in China. The fast Lagrangian analysis of continua is used to simulate the response of piles under the complete process of metro tunneling(deactivation of soil element and activation of the lining). The adjacent rock around the tunnel is classified into three regions：Region I (upper adjacent stratum of tunnel)，Region II (45°-upper-lateral adjacent stratum of tunnel)，and Region III (lateral adjacent stratum of tunnel). In each region one typical pile is chosen to calculate and analyses in detail. Numerical simulations are performed concerning，respectively，side-friction force of pile，tip resistance of pile and pile axial loading. Contrasting analyses are performed both in the response of typical piles in different regions，and in computer calculating value with field measuring value. Results of numerical simulations show that the effect on the carrying capacity of pile lies mainly in the effect of construction metro tunnels on the side-friction force and the tip resistance of pile. The effect is widely different from stratum to stratum where the pile tip is located at. The complicated rules of side-friction force and tip resistance of pile result in the complicated rules of pile axial loading，thus it influence the carrying capacity of pile-foundation at last. It is necessary to take positive measures，such as stratum grouting stabilization or foundation underpinning，etc.，to deal with the carrying capacity and the settlement of pile-foundation. The results are valuable for similar engineering projects.