Because of the unique characteristics of Jiweishan landslide，it is necessary to make clear special geological environment，geological structure and geometry of failure rock masses，and mechanical properties of both rock masses and sliding plane for studying the failure mechanism of Jiweishan landslide and distinguishing from other types of rock landslides. In this paper，the stability of the sliding body and crack causes were analyzed based on detail analyses of engineering geological environment and conditions of Jiweishan landslide as well as physical and mechanical properties of rock masses. New elastic mechanics formulas for evaluating slope stability and creep compression behaviors of rock masses were derived based on geometry，geological structure and tectonic characteristics of the sliding body，distribution of karst fractures of rock masses as well as the large compression stress condition. The shear strengths of the weak sliding plane and the front side wall were calculated，and the compression amount of the sliding rock mass，i.e.，the opening width of the crack T0，was also estimated. It is revealed that T0 is an extension fissure caused by the compression of the sliding body rather than a tensile crack suggested by other literatures and that the creep sliding results from the compression of the sliding body. It is also pointed out that T1 is a tensile fissure based on the side-aligned geometric weight center of the sliding body，center-tilted compression and large lateral compression amount. Calculations by the developed formulas show that the stress and strain of the front sliding body are the highest and reach the compression strength of the rock mass，and hence，the front rock masses are broken by compression and the front side wall is also sheared off，which explains the failure cause of the sliding body. Moreover，the compression stress within different segments of the karst fractured limestone，failure stress of the front rock masses，compression amount and compression modulus and directional fracture ratio were assessed based on the formula of the elastic compression model.

On the basis of dynamic disaster characteristics induced by deep mining and the advantages and disadvantages of energy-releasing bolts，a novel kind of J energy-releasing bolts consisting of anchorage(damping) module，deformation module，blending section and anchorage section was developed，and static pullout model and dynamic impact consititive model of J energy-releasing bolts were established. The dynamic impact consititive model consists of spring and damping elements in parallel. Given an initial dynamic impact load，the oscillation amplitude of J energy-releasing bolts will quickly attenuate along the bolt axial impact direction with increasing the damping ratio，that is，the greater the damping effect of J energy-releasing bolts，the more quickly the dynamic impact energy releases. The static pullout test and the dynamic impact test of J energy-releasing bolts were done in the Candian CANMET laboratory. The experimental results show that the static pullout load is greater than 190 kN，and that the bolt can not only allow large sliding displacement but also provide a large constant anchorage force under static pullout condition. Under multiple dynamic impact loading condition，the peak load of J energy-releasing bolts exceeds 250 kN every time. The release energy of J energy-releasing bolts exceeds 19.3 kJ under one time dynamic impact condition and the total energy release capacity reaches 46.5 kJ，which shows that J energy-releasing bolts can bear multiple dynamic impact loading and the energy release capacity is stable. Due to the objective existence of joints in rock mass，the energy-release bolted rock mass can generate dilatation and tensile failure in the joint surface of rock mass under dynamic impact condition such as rockburst etc.，but the support structure system in the surface of the tunnelling(stope) will not be damaged by the dynamic impact，which can effectively release the kinetic energy accumulated in the rock mass induced by high magnitude rockburst. The research can provide new support idea for preventing and controlling the mine dynamic hazards induced by deep mining.

The fracture path of jointed rock masses has always been a hot and difficult problem in the fields of rock mechanics and engineering geology，and how to quickly and accurately calculate the fracture path of rock masses is of great significance in theory and engineering. In the present paper，a new method to determine the fracture path of jointed rock masses，taking the stress transmission in rock mass as fluid flow，is proposed based on flow field theory，and the feasibility of applying the flow field theory to the calculation of the stress field of jointed rock masses is verified based on the principle of equivalent analysis. The flow field analysis around the joint by using the theory of flow shows that there exists a flow region and a reverse flow area at the end of the joint，which verifies the stress concentration and the formation of tensile stress zone at end of the joint from the angle of the flow field. Finally，a method for determining the fracture path of rock masses is proposed according to the distribution of flow field concentrated zone and verified by the model test.

To study dynamic response mechanisms of layered cemented backfill pillars under the stimulation of far-field blasting，a multi degree of freedom structural response model method of layered backfilling bodies with different cement-sand ratios is firstly established by combining the structural characteristics of layered cemented pillars and its interaction with surrounding rock and backfill. Taking three layered pillars of a copper mine as calculating examples，the stability of the pillar is predicted by comparing the results of numerical simulation and field monitoring，and the action mechanism of different stress wave frequencies is also studied. The results show that the analysing results of the model method are basically consistent with those of numerical simulation and field monitoring under far-field blasting stress wave condition. The cement-sand ratio significantly affects the velocity and displacement response of the backfilling body and determines the responding peak value of the backfilling body. The lower the cement-sand ratio，the larger the vibration period，velocity and displacement response of the layered backfilling body and consequently，the worse the structural stability. The backfilling body with a low cement-sand ratio is the weakest of the pillar structure and is prone to failure. The peak values of the velocity and the displacement response of the backfilling body are obviously affected by the frequency of stress waves，and both them present a single peak with the former lagging behind the latter. At the low frequency state，the vibration period of the backfill pillar increases，and the increase rates of the velocity and the displacement response are lower first and then larger. While the frequency is close to the natural frequency of the backfilling body，resonance phenomenon of the backfilling body occurs and the peak values of the velocity and the displacement response reach their maximums. At the high frequency state，the peak values of the velocity and the displacement response continuously decrease. The research results provide theoretical supports for judging pillar stability of backfilling bodies under the stimulation of far-field blasting.

The engineering disasters caused by deformation and failure of expansive rocks occur frequently，and disaster-inducing mechanisms need to be further studied. In the present study，through indoor swelling and shrinkage tests and combined with the suction theory，the saturation and swelling-shrinkage characteristics of unsaturated and undisturbed strong expansive rock in Nanning were studied. The swelling rate tests were performed in both cases of different initial moisture contents without vertical load and different vertical loads，and the shrinkage tests were carried out under the condition that the samples are sufficiently saturated and naturally dried. The research results indicate that，during the process of water absorption and swelling of the unsaturated expansive rock，both the saturation and the swelling rate show three-stage growth for two cases of no vertical load and the vertical load less than the expansive force，that the relationships between the saturation and the swelling rate of the two cases are respectively exponential and non-linear，and that the variation of the swelling rate lags behind that of the saturation，i.e.，the expansive rock reaches saturation state first. When the vertical load is equal to the expansive force，the expansive rock absorbs water and reaches saturation state without volume variation. The variation tendency of the saturation of the expansive rock is influenced by the initial water content at the initial stage of water absorption，especially near the shrinkage limit，but the saturation after swelling stabilization is insensitive to the vertical load. It is also shown that，during the shrinkage process of initial saturated expansive rock，the saturation develops in a three-stage attenuation mode and there is a negative correlation between the saturation and the linear shrinkage. For unsaturated expansive rocks in Nanning area，the saturation changes while the swelling-shrinkage deformation almost keeps constant when the saturation is in the range of 80% and 90%. The corresponding research results can provide a scientific basis for reasonable construction of swelling-shrinkage constitutive model of expansive rocks and a guide for the evaluation of the stability of unsaturated expansive rock engineering.

The stability and control of roadway composite surrounding rock(coal and rock) under inclined thin coal seam mining is a prominent problem in coal resource mining，and hence，it is of great significance to study the failure mechanisms of coal-rock-bolt composite anchor solid formed by coal，rock mass and the support structure. A series of uniaxial compression tests were carried out on horizontal anchored and non-anchored of inclined coal-rock composite specimens(15°，30° and 45°，respectively). The results show that the stress-strain curves of the non-anchored specimens at the post-peak stage stepwise decrease with many small multi-peak fluctuations. When failure of small-angle coal-rock composite specimens occurs，the stress of coal mass acting on the coal-rock structural plane is more uniform，the failure cracks mainly distribute in coal mass and the strength difference of samples is small. When the combination angle increases(＞15°)，the local stress concentration is formed on the coal-rock structural plane，and composite tension and shear failures of coal mass and rock mass occur simultaneously. At this time，the strength of coal and rock mass is determined by coal，rock and bolts together. The cumulative value of the circumferential strain of coal and rock increases with increasing the combined inclination，and the cumulative value of the strain of the anchored specimen is less than that of the non-anchored specimen. Additionally，the cumulative destruction between the coal part and the rock part presents a lag effect，and the coal body fails 50 s ahead of the rock mass. Finally，the mechanical characteristics of the“coal-rock-bolt”inclined composite specimens were discussed，and the influence of the anchorage angle between the bolt and the coal-rock structural plane on the strength of the coal-rock system was analyzed. The experimental results are in good agreement with the theoretical prediction model.

The research on the mechanical properties of granite after high temperature thermal damage is of great significance for the successful implementation of dry hot rock geothermal demonstration project in Gonghe basin，Qinghai province，and it can provide mechanical parameters related to thermal damage of rock for the drilling project，artificial reservoir design and construction. Using macroscopic mechanical test method combined with the microscopic CT scanning，compressive strength，shear strength and tensile strength of granite from Gonghe basin，Qinghai province after high temperature thermal damage are studied，and the influence of natural cooling on crack formation of high temperature granite samples is also investigated. Through fitting the test data，empirical formulas of the compressive strength，elastic modulus，tensile strength，cohesion，internal friction angle with temperature are obtained，and a shear failure strength criterion of granite under thermo-mechanical coupling is established. The influence of the temperature on brittle-ductile transition of granite is discussed，and it is found that，at the temperature of 500 ℃ to 600 ℃，the ductility plays a dominant role. The cooling rate is closely related to the density of thermal fracture of granite. For the first 400 s of the natural cooling process of granite in the air，the cooling rate is the highest and the temperature gradient is the largest. Especially for the first 150s，the thermal crack is most severe. The research results can provide theoretical basis and technical support for the development and utilization of dry hot rock in China，and also enrich and develop the theory of high temperature rock mechanics.

Coal micro mechanical properties and failure mechanisms are of key importance to supplement and explain the physical and mechanical properties of coal. Nanoindentation tests were carried out to obtain micro mechanical properties of Zhaozhuang coal，molecular dynamics simulation of the macromolecule matrix of Zhaozhuang coal was performed，and their results were compared with each other. The results show that the average hardnesses of Zhaozhuang coal in static and dynamic loading modes are respectively 0.423 and 0.560 GPa，and the average elastic moduli are 4.452 and 5.200 GPa，respectively. The Weibull distribution moduli corresponding to the elastic modulus and hardness of Zhaozhuang coal under the two loading modes are greater than 20. The failure mechanisms at the molecular scale were revealed through nanoindentation molecular dynamics simulations of Zhaozhuang coal macromolecule matrix. The hardness and elastic modulus of Zhaozhuang coal molecular simulation were obtained using Oliver-Pharr method and Hertz theory，which are approximately agreed with the tests. In the simulation process，the potential energy of the system increases while loading but decreases while unloading. The final potential energy is higher than the beginning because of the plastic deformation. When the indenter is embedded，the atomic dense area is formed due to mutual extrusion of coal macromolecules and further，the damaged layer occurs because of the loss of the original bond strength. The research on the structure of coal macromolecule matrix by using radial distribution function and bond angle distribution shows that in the process of coal matrix failure，the order degree of coal macromolecule decreases and the ring structure in coal macromolecule plays an important role in failure resisting.

In order to study the rock-breaking mechanisms and technical advantages of the two-step cutting technology，the stress wave propagation，the effective stress peak and the rock failure type of the two-step cutting technology and the ordinary wedge cutting are compared by numerical simulation. Laboratory test and field test are carried out to analyze the advantages and disadvantages of the two types of cutting technology. The results show that the two types of cutting have two stress peaks，but present obvious difference in the cutting mechanisms due to the different energy release orders of blasting. For the ordinary wedge cutting，the 1st stress peak is created by cutting hole blasting with a form of compressive breaking，while the 2nd stress peak results from mid-hole blasting companied by compressive failure of the bottom rock of the cutting hole and followed by throwing rock. For the two-step cutting，the 1st stress peak is created by mid-hole blasting，leading to compressive failure and creating a pre-cracking zone，and the 2nd stress peak is created by cutting hole blasting，presenting main compressive failure and secondary tensile failure and creating the compressive and tensile failure zones which form a three-zone coupling failure with the pre-cracking zone. Both model experiment and numerical simulation show that the shape of the ordinary wedge cutting is similar to a horn and the rupture surface is 30° with respect to the blasthole，while that the two-step cutting is similar to a prism shape and the rupture surface is 0° with respect to the blasthole. Model experiment and engineering practice also indicate that the two-step cutting technology is superior to the ordinary wedge cutting technology in terms of blasting footage，blasthole utilization rate and bulk rate，and has good applicability.

Based on the elastoplastic solution of deep buried tunnels considering strain-softening characteristics，the failure mechanism of short bolt support in soft rock tunnels under high ground stresses is analyzed by means of neutral point theory of bolts，and the necessity of lengthening the bolts in soft rock tunnels under high ground stresses is demonstrated. On one hand，the increase of the confining pressure on the anchor section can improve the bonding strength between the rock and the bolt，on the other hand，the enhancement of the difference of the surrounding rock displacements at the head and end of the bolt helps to improve the anchoring effect of the bolt to the surrounding rock. By taking the supporting body with intensive short bolts as composite rock mass and the support of long bolts as an equivalent support force acting on the tunnel wall，a combined support model of long and short bolts is established. The characteristic curve of the surrounding rock supported by long and short bolts is obtained by considering the interaction between the bolts and the surrounding rock. Comparison between the characteristic curves of the surrounding rocks，respectively reinforced by short bolts and the combined support technology of long and short bolts with the same amount of bolts per meter of the tunnel，illustrates the effectiveness of the combined support technology for deformation control of soft rock tunnels under high ground stresses. The combined support technology of long and short bolts，considering the interaction between long bolts and the surrounding rock，provides a calculation method for the support length of long bolts in soft rock tunnels under high ground stresses.

The fractured rock mass in cold regions is often affected by the freezing and thawing action. In order to study the influence mechanism of the dip angle of rock bridge on frost heave expansion process，fracture failure characteristics and strength loss of fractured rock mass，double-fracture sandstone samples with different dip angles of rock bridge were prepared with similar materials，and freezing and thawing cycles with and without water injection and a series of uniaxial compression tests were performed. The results indicate that，driven by the frost heaving force，the frost heaving cracks continue to expand along with the growth of dendritic microcracks，and that the outer tip of the frost heaving crack mainly propagates along the initial crack direction while the inner tip tends to deflect towards the outer tip of another prefabricated crack. The greater the dip angle of the rock bridge，the more obvious the deflection effect will be. The uniaxial compression failure mode of the sample is easily affected by the frost heaving crack. When the inclination angle of the rock bridge，，is between 90° and 135°，shear failure occurs in the direction of the frost heaving crack，which leads to a significant decrease in the strength of the specimen. When =180°，the frost heaving crack is no longer the main cause of uniaxial compression failure of the specimen and has little effect on the strength loss and fracture characteristics.

In order to research the relationship between macro-expansion process and micro-evolution of water-rich slate，the expansion rate test under lateral restraint and the expansion force test under constant volume condition of slate taken from Zhuxi county，Hubei province，were performed to investigate macro swelling deformation of slate. The types of sample minerals were determined by X-ray diffraction(XRD)，the micro- structure of samples after water absorption was observed by scanning electron microscope(SEM) for investigate the internal factors of the expansion of slate after water absorption and the evolution law of the micro-structure，and the T2 spectrum distribution of slate was obtained by NMR for studying the micro-mechanism of mud expansion process of slate. The results show that under the rich-water environment，the expansion rate of slate increases rapidly in the early stage，then tenderly and tends to be stable，while the expansion force shows a slightly decreasing process after quickly increasing up to the maximum. With the prolongation of soaking time，the content of clay minerals in slate increases and the solution tends to be weak alkaline as a whole. The T2 spectrum of natural slate shows double peaks and mainly consists of small pores. After water immersion，the T2 spectrum shows three peaks and the internal macro-pores appear. The total pore volume increases first and then decreases with a maximum value at 2 h of immersion. After water absorption，mineral particles of slate begin to expand，resulting in the increases of the particle volume and the contact force between particles，and consequently，stress and strain tensors increase macroscopically，which explains the internal causes of expansion deformation and expansion force of slate. The slight dissolution of clay minerals makes the expansive stress decrease slightly，which explains the phenomenon of the slight drop of the expansive stress after reaching the maximum. This study can provide a theoretical support for the study of swelling mechanisms of expansive rock.

Creep behavior of rocks under high stresses is one of the hot issues in the study of deep buried chamber stability. To study creep characteristics and long-term strength of argillaceous siltstone under high stresses， triaxial compression rheological tests were carried out on argillaceous siltstone specimens under graded incremental loading. The experiment results show that the creep of argillaceous siltstone has viscoelastic characteristics under low stresses and elastoviscoplastic characteristics under high stresses. Based on separating instantaneous elastic strain，viscoelastic creep and viscoplastic creep from the total creep of argillaceous siltstone under high stresses，the functional relationship between the steady viscoplastic creep rate and the stress was established. It is suggested that the threshold stress corresponding to the steady-state viscoplastic creep rate can be regarded as the long-term strength of argillaceous siltstone under high stresses. It is also shown that the long-term strength of argillaceous siltstones under high stresses，determined by the developed function between the steady viscoplastic creep rate and the stress，is 70.5% of the uniaxial compressive strength. The research provides a reasonable method for determining the long-term strength of rocks under high stresses.

Bolting effect of prestressed anchor cables in expansive soil layers is greatly affected by the water content of the stratum，and the prestress loss of the anchor cable is closely related to the stress relaxation of the soil. Taking the expansive soil in Chengdu area，Sichuan，as the research object，indoor model tests were performed to study the prestress loss law of pretressed anchor cables in the expansive soil layer with four different water contents. In terms of the unique viscoelastic-plastic mechanical characteristics of expansive soils，a strain-equalization calculation model of expansive soil-anchor coupling effect and the corresponding constitutive and relaxation equations were proposed. Comparison between the developed model and model test results also carried out. The results show that the prestress attenuation can be divided into rapid attenuation，slow attenuation and relative stabilization stages，and that the attenuation speed and amplitude of prestressed anchor cables increase with increasing the initial water content of the expansive soil layer. The initial prestress loss of the prestressed anchor cable in the expensive soil layer can reach up to 80% of the total prestress loss. The calculation results by the coupling model is basically consistent with the test data，which indicate that the model is capable to be used to evaluate the bolting effect of anchor cables in soil layers with known physical parameters.

An experimental apparatus was developed to study the water-heat-vapor migration characteristics of unsaturated coarse-grained filling of high-speed railway subgrade under freezing and thawing cycles，and a fluorescein tracer was used to trace the rising height and intake behavior of liquid water. A series of key technological experiments were conducted to validate the utility of the test method and the reliability of the apparatus，and freeze and thaw tests were performed to investigate the water-heat-vapor migration characteristics of unsaturated coarse-grained filling in a process of thrice freezing and twice thawing with 72 hours of the freezing time and 12 hours of the thawing time. The results indicate that under a constant temperature freezing mode，the frost penetration increases with increasing the freezing numbers. The external water infiltrates mainly in the form of vapor into the soil sample during freezing and the internal water comes out during thawing. The second freezing provides the maximum water intake. The ice accumulates on the top base pedestal and the increasing range of the water content in the frozen zone is relatively even at the end of the test. The water-vapor migration and phase change of the coarse-grained filling induced by freezing and thawing cycles could lead to an ice layer formation and a change in the strength of the high-speed railway subgrade.

In the underground repository of high-level wastes，strong alkaline cementitious material dissolved by groundwater from the lining concrete will penetrate into bentonite buffer，resulting in a certain degradation of the performance of the buffer barrier. A diffusion cell was particularly designed to simulate the diffusion process of KOH solution into compacted GMZ bentonite specimens，so to investigate the possible changes in clay minerals and microstructure under elevated temperature for the purpose of long-term evaluation of GMZ bentonite buffer in China. Totally，24 sets of KOH diffusion tests were conducted on bentonite specimens with an initial dry density of 1.80 g/cm3，covering combinations of pH = 12.6，13.0 or 13.5，temperature of 30 ℃ or 60 ℃ and reaction time of t = 7，14，21 or 28 d. As soon as diffusion tests terminated，bentonite specimens were disassembled to carry out X-ray diffraction(XRD) and scanning electron microscopy(SEM) analysis. Research results verify that the dissolution loss of montmorillonite in bentonite has a positive correlation with pH and temperature and that the dissolution mainly concentrate within 0‐2 mm from the contact surface with a max drop from original 44.4% to 25.9%. The alkaline dissolution of wing-like gels generated originally during bentonite hydration is responsible for the montmorillonite dissolution. Bentonite microstructure damage resulted from alkaline solution moderates with increasing the diffuse depth from the contact surface，accompanied by a decrease of the apparent porosity. Macro fissures on the contact surface are visible by naked eyes，aggregate destroy occurs within 0–4 mm from the contact surface but the microstructure almost keeps changeless while deeper than 4mm. With respect to the long term chemical evolution of bentonite barrier，further attention should be paid to solution chemistry，hydraulic condition and time scale of mineral-solution reactions.

将人工合成类纺织废弃涤纶布料进行开松、分梳、切断形成涤纶纤维纱，将具有良好抗酸碱腐蚀性能的涤纶纤维纱按照一定掺加比例与素黄土拌合制成纤维纱加筋黄土。利用新型伺服液压缸驱动动单剪仪对素黄土及纤维纱加筋黄土进行动力特性试验研究。分析其动应力–应变关系、阻尼比特性、动强度特性及震陷等变化规律。试验结果表明：同一动剪应变条件下，纤维纱加筋黄土的动剪应力大于素黄土；同一破坏振次条件下，随着纤维纱掺加比例的增加，动剪应力呈现先增大后减小的变化趋势，当纤维纱掺加比例为0.20%时，动剪应力最大；随着法向固结应力的增大，素黄土及纤维纱加筋黄土的动剪应力随之增大；同一法向固结应力条件下，阻尼比随着纤维纱掺加比例的增大而增大；不同纤维纱掺加比例的加筋黄土动剪应力比与破坏振次的关系可近似归一化处理；一定振次条件下素黄土及纤维纱加筋黄土的残余应变均随着循环动剪应力的增大而增大；同一循环动剪应力条件下纤维纱加筋黄土的残余应变小于素黄土的残余应变；同一循环动剪应力条件下随着纤维纱掺加比例的提高，加筋黄土的残余应变减小；随着振次的增加，残余应变呈逐渐增大的变化趋势；震陷临界动剪应力随纤维纱掺加比例的增加呈先缓慢增大，再急剧上升，最后趋于稳定的变化趋势；根据试验曲线及相关数据确定出提高黄土抗震陷性能的最佳纤维纱掺加比例为0.20%。

Cracks as a damage type of earthen sites not only destroy tabia structure integrity but also degrade mechanical properties due to providing preferential paths for rainfall infiltration. Therefore，the repair of tabia cracks is an important part of protection and reinforcement of earthen sites. Due to that calcium carbonate is one of the main components of the tabia，the use of microbially induced carbonate precipitation(MICP) technical to repair and protect the tabia is not only environmentally friendly but also compatible with the substrate. In this paper，a crack repair method dominated by MICP was proposed to repair the cracks of the tabia，and the repair effect was evaluated by experimental test. First，the influencing factors of MICP test and the reinforced soil column test were carried out to determine the suitable parameters for repairing cracks，including the concentrations of bacteria and cementation reagent，filled soil particles and the number of grouting cycles. Then，the pre-damaged tabia samples were repaired using MICP with the suitable parameters，and the repair effect was verified. The results show that，when the crack width is 5 mm，the recovery ratios of the average flexural strength and shear strength of the specimens repaired by MICP are respectively 79.92% and 88.54%，showing a very satisfactory repairing ability，while that the recovery ratio tends to decrease as the crack width increases. In addition，the static contact angle test results show that the MICP not only repairs the crack but also enhances the hydrophobicity of the crack. MICP technology can be used as an effective method to repair cracks in the tabia.

In this paper，a finite element model was developed for the first time to simulate the driving process and response of a pile into a saturated clay soil from the ground surface to an embedment depth. Based on the calculated results，the influence zone of pile driving was determined and the response of the excess pore water pressure of the soil to pile driving was presented. For a given depth，the buildup of the excess pore water pressure has good dimensionless characteristics with respect to the pile diameter，in other words，the distributions of the maximum excess porewater pressure in the radial direction for different pile diameters basically coincide with each other when the radial distance is normalized by the pile diameter. Moreover，it is found that，in a semi-logarithmic coordinate system，the normalized maximum excess pore water pressure approximately follows a linear relationship with the radial distance. Comparisons among finite element simulation，calculation by the theory of cylindrical cavity expansion and the field measurements indicate that the finite element analysis results are in a good agreement with the published field measurements while there exists a discrepancy between the finite element analysis results(or field measurements) and calculation results by the cylindrical expansion theory，which is resulted from that the shear force around the pile shaft is neglected in the cylindrical expansion theory while the actual piling process is fully simulated in the finite element analysis.