The aim of this paper is to provide a theoretical basis for rock burst failure prediction. The digital images of fragments ejection were captured by two high-speed cameras during the tests on granite rock burst. The binocular stereovision technology was used to obtain three-dimensional(3D) coordinates and volumes of fragments. Two key parameters were utilized to calculate the ejection velocities of fragments. The theoretical model calculating the ejection velocity was modified according to the measured values. It was found that the stress attenuation constant b obeyed the normal distribution，with the mean and variance 1.53×104 and 4.83×107 respectively. The modified formula have one unknown variable less than the unmodified model. That is to say，if the mass of fragments and static stress state at burst point are known，the statistical distribution of ejection velocity can be obtained. The mass of most of the ejected fragments is less than 0.25 gram. The statistical result shows that the kinetic energy of fragments，with length l＜20 mm，is dominant(more than 86%).

Due to the complexity and hidden nature of rock in engineering，traditional modeling and analysis in rock engineering are based on the data acquisition techniques and numerical methods with low accuracy. This paper integrates a series of high-precision methods and techniques into the iS3(infrastructure smart service system)，an integrated platform of engineering information developed by the authors. This system integrating software and hardware is used for data acquisition，analysis and service of rock tunnels. Binocular digital photography and 3D laser scanning are applied in iS3 to acquire and reconstitute surface and joint information of rock. Based on the high-precision information，3D mesh and block cutting algorithm are used to generate the information for numerical computation，which is integrated into the same 3D model with digital information from data acquisition. 3D finite element analysis module with nonlinear failure criterion and integrated computation module using the key block analysis and discontinuous deformation analysis(DDA) are implemented in iS3 to provide the high-precision numerical results. The service module of iS3 includes the functions such as the project management，information presentation，safety analysis，aided design and etc. This system realizes high-precision and remote service and has been applied in practical engineering cases.

The mechanism of fracture development and bolt anchoring of roadway(tunnels) rockburst have not been fully studied. The bi-axial compression tests to the rectangular hard rock samples with and without anchoring were carried out using the true three axis loading and unloading test system developed in-house. The development of stratified burst of hard rock and the mechanism of bolt anchoring were discussed. The layer burst phenomenon occurred in the hard rock tests. The fractal dimension of burst surface from the free surface to deep was mainly between 1.3 and 1.8. The fractal dimension of burst surface was reduced by the enhancement of the frictional action of the burst surface. The dominated fracture form was gradually transited from the tension fracture to the shearing fracture. Each layer was more or less accompanied by the secondary layer fractures at the same time. The number and extent of bursts were greatly reduced by the bolt anchoring and the layer by layer burst of hard rock was restricted. A formula for the number of layers undergoing burst near the surface was obtained through theoretical analysis. The rock with the stratified burst was considered as the layered rock and the composite beam theory for bolt control was proposed. The stratified burst was mainly the result of tension due to compression. The tensile strength of the intact rock was greatly improved and the number and scope of the stratified burst were greatly reduced by the bolt anchoring.

In order to obtain the shape of rational stop line，a model test was undertaken to study the disturbing characteristics below roadway with the axis perpendicular to the excavation orientation during the excavation of upper mining face. The test site，Jining #3 coal mine has a deep coal seam. The PAC acoustic emission，static resistance strain gauge and digital speckle are utilized. The events development，the strains at different locations and the overall deformation of surrounding rock below roadway were obtained. The acoustic emission characteristics of similar material were monitored during the uniaxial compression experiment and the results reflected the damage characteristic of similar material sample. It is concluded that the rational stop line should contain the excavation influenced zone l1 of disturbed roadway，the influenced zone l2 ahead of mining face，and the minimum safety distance l to avoid these two zones to influence each other. During the upper mining face excavation，the scope of l，l1，l2 were obtained by monitoring the strain and acoustic emission characteristic of surrounding rock and the total deformation was monitored in below roadway with the method of digital speckle.

Due to the existence of gravels in a glutenite formation，the geometry of hydraulic fracture becomes more complex，which makes the stimulation treatment difficult. In order to investigate the propagation mechanism of hydraulic fracture，laboratory experiments were performed on six natural glutenite samples，using a large scale tri-axial fracturing simulation system. The influences of the horizontal stress difference，gravel size and distribution，fracturing fluid viscosity and pumping rate on the fracture propagation were analyzed. The experimental results show that a single planar hydraulic fracture was created when the small gravels dominated in the glutenite sample. This indicates that small gravels have no obvious influence on the fracture propagation. By contrast，the hydraulic fracture was deflected along the interface of gravels and resulted in a complex fracture geometry with multiple tortuous branches in samples with large gravels. This phenomena is more distinctive when a sample with randomly distributed large gravels was hydraulically fractured under a lower horizontal stress difference. Additionally，a higher breakdown pressure was observed in the injection pressure curve when the hydraulic fracture initiated within a high-strength gravel. The fracture branching or deflecting is likely to reduce the fracture width. The fracture width was effectively increased when the high-viscosity fracturing fluid such as guar gel was used which is helpful for preventing sand plug.

Split Hopkinson pressure bar(SHPB) apparatus was used to study the factor of dynamic strength increasing，the density of dissipation energy and the fragment size of limestone，dolomite and sandstone subject to impact loading. SHPB has some difficulties to measure the higher strain rate and dynamic damage process for rock materials. The grain-based model was thus built by using the high resolution scanning and image processing technique combined with the discrete element method. The accuracy of numerical simulation was verified with the experimental SHPB results. The results indicated that the dynamic failure strength of rock material was rate dependent strongly，but the elastic modulus did not increase significantly with the increasing strain rate. The semi-empirical formula for evaluating the factor of dynamic strength increasing is consistent with the Ханукаев equation. The failure pattern of the rock transforms from the intact→splitting damage→pulverized damage with the increasing strain rate. This phenomenon is determined by the number of the micro cracks activated and the interaction between the cracks. The increase of the crack density and the change of the crack propagation path are the mechanism of the dynamic fracture of the rock，and the macrosopic responses are the rate effect and fragmentation of the material.

In order to study the mechanical properties of water-saturated coal specimens under coupled static-dynamic loadings，contrast experiments between 3D coupled static-dynamic loadings and 3D static loadings on both water-saturated coal specimens and natural coal specimens were conducted by using the improved split Hopkinson pressure bar(SHPB) and the RMT–150 test systems. Results shows that，under 3D static loadings，the variation of peak strength of natural coal specimens is 10.49%，while the variation of peak strength of 7 d saturated specimen is 59.98%，with a softening coefficient of 0.81. Under 3D coupled static-dynamic loadings，when the axial pressure is less than 55% of the uniaxial compression strength，the dynamic strengths of the 7 d saturated coal specimens are higher than those of the natural coal specimens，the increased strength of 7 d saturated coal specimens are 7.85%–18.44%(confining pressure 4 MPa) or 8.71%–19.84%(confining pressure 4 MPa) compared to the natural coal specimens. In the case of different confining pressures with the same axial pressure，with the increase of confining pressure，the dynamic strengths of the 7 d saturated and the natural specimens are both increased. Moreover，the increment of dynamic intensity of 7 d saturated coal specimens is larger than that under the natural state，indicating that water-saturated coal specimens are more sensitive to confining pressure. Experimental results show that the effect of water-saturation to the strength of coal specimen is significant，but the strain rate plays a controlling role. The coupling effect between the water and coal fissure causes the larger stiffness under the conditions of medium or high strain rate. The dynamic strength of water-saturated coal specimens increases under 3D static-dynamic loadings.

In order to improve the efficiency of methane extraction from coalbed with low permeability，to reveal the effect of high voltage electric pulse on hydraulic fracturing in coal and the development of crack expansions，the laboratory tests of hydraulic fracturing using the high voltage electric pulse on coal samples were carried out under pure hydrostatic(3 MPa) and the same hydraulic pressure(3 MPa)，different discharge voltages(5，10 kV). CT scanning was employed to analyze the initiation，development and distribution of the internal cracks in coal sample. The numerical analysis of the development of fissures and the periphery stress around the fissures under the action of hydraulic electric pulse were carried out. The results show that under the same hydrostatic pressure，the effect of high voltage pulse on hydraulic fracturing of coal is greater than hydrostatic pressure fracturing. The higher the discharge voltage is，the greater the tensile stress in the crack tip is and the crack is easier to produce and develop. The higher the discharge voltage is，the more cracks there are，the earlier the crack initiation，the longer and wider the crack extensions are，and the better the crack fracturing effect. The results of the study proved that the high-voltage pulsed hydraulic fracturing method is effective and feasible.

The percolation test of whole process to the impure salt rock of a natural gas reservoir in China was carried out using the THMC rock triaxial test system in Sichuan university. A multi-factor coupled percolation model considering simultaneously the confining pressure，dilation and impurity content was established by curve fitting the test results. The experimental research shows that the content，distribution and composition of the impurity all have the significant influence on the permeability of the salt rock. The permeability of salt rock with different impurity decreased after damage recovered. The plastic deformation can be divided into two stages. In stage one，the permeability increased rapidly，while in stage two，the permeability increased slowly and even decreased. The permeability increased significantly after the sample failure and the permeability maintained at a stable level in the residual phase. The low permeability interlayer restricts the vertical permeability. The salt rock with the mud component has the lower permeability than the salt rock with glauberite impurity. The multi-factor coupled percolation model shows that the higher the confining pressure，the lower the permeability，and the greater the volumetric strain dilation，the higher the permeability. When the impurity content is more than 0.46，the permeability increases with the increase of impurity content. When the impurity content is less than 0.46，the permeability decreases with the increase of impurity content.

In order to study the effect of water damage on the characteristics of fracturing of mudstone，three-point bending test was carried out to the semi-circular bend(SCB) mudstone specimens that have been soaked in water for different durations. The real-time monitoring with PCI–2 type acoustic emission system was conducted on the fracturing process of the mudstone specimens. The results show that fracturing behaviors of the mudstone is significantly influenced by water-rock interaction. The peak load of the mudstone specimens decreases with the soaking time increases. After being soaked for 200 minutes，the fracture toughness of mudstone from pure mode I to pure mode II decreased respectively to 53%，56.5%，61%，64%，64.7% and 67.6% of those of the intact specimens，and the failure characteristics of mudstone was changed from brittle to ductile. The length of fracture process zone(FPZ) of the mudstone SCB specimens soaked for different durations was confirmed by the acoustic emission(AE) positioning. As the soaking time increases，the length of FPZ decreases and the accumulative number of acoustic emission events increases. The experimental ratio of Keff/KIC and the theoretical ratio based on the modified maximum tangential stress(MMTS) criterion that takes into account the T-stress matched well when the mudstone SCB specimens are not soaked or only soaked for a short time. However，as the soaking time increases，the experimental results of SCB specimens diverge from the theoretical values gradually. When the soaking time reaches 200 minutes，the deviation becomes very distinct.

The homogeneous，layered and block surrounding rocks anchored by crossing cables were studied in two groups of modeling tests to improve the explosive resistivity of country rocks. The macroscopic failure mode，the swelled shape，the distribution of cracks and the size of the explosion cavity of both reinforced and unreinforced surrounding rocks were studied. The research results showed that the crossing cables increased the tension strength and shear strength of rock，the explosive resistivity of country rocks was improved notably. The degree of model destruction was significantly influenced by rock characteristics. For the anchored rocks，the swelled height of the block models are bigger than the ones of homogeneous and layered models. The rock characteristics are the main factors affecting the crack distribution of the models. The size of explosion cavity of the homogeneous model anchored by the crossing cable is the smallest，of the block model is medium，and of the layered rock is the biggest.

The high pressure gas in coal is mainly in adsorbed state. In order to study the influence of adsorbed gas content on outburst，He，N2，CH4 and CO2 have adsorption in increasing order and were thus used to simulate the different adsorbed gas contents under the same pressure. The above four gases of 0.75 MPa were applied to the briquettes of the same properties to simulate the coal with the same free gas content and with different adsorbed gas contents. 16 tests were conducted to 4 kinds of briquettes with different strengths. 9 outburst phenomena occurred in these tests，and the test with He which cannot be absorbed also burst out. These test results show that the risk and the intensity of outburst increased when the adsorbed gas content increased. A method to determine the expansion energy of adsorbed gas was proposed. The elastic energy of coal，the expansion energy of adsorbed gas and free gas，the energy consumption of coal crushing and throwing power were calculated. The potential energy and energy consumption were basically equal，which proved the rationality of the measurement method of expansion energy of adsorbed gas. Energy analysis indicated that the expansion energy of adsorbed gas accounted for 6.5%–25.6% of the potential energy，and the ratio increased with the increase of adsorbed gas content.

To study the bearing behavior of tunnel anchorage in soft rock with an underlying weak interlayer，a tunnel anchorage model with the size ration of(1∶10) to a bridge?s tunnel anchorage was used for field test. The loading，creeping and failure tests were carried out to the tunnel anchorage model. The tunnel anchorage in soft rock with an underlying weak interlayer has the carrying capacity and the long-term stability according to the research results. The curves of surface settlement of the rock behind the tunnel anchorage show the shape of “M” and the curves of surface settlement of the rock of the tunnel anchorage show the shape of “N”. The surface settlement of the surrounding rock reduced gradually from the front to the rear of the tunnel anchorage.

The impact test and dynamic Brazilian test using the pendulum hammer driven SHPB apparatus were conducted to measure the viscosity coefficient of sandstone and artificial rock and to examine the loading rate effect. The viscosity coefficients of sandstone and artificial rock A and B are 100，10 and 5 kPa•s respectively and were determined with the combined method of experiment and numerical simulation. The dynamic tensile strength of the sandstone and artificial rock samples increase with the loading rate，showing the strong strain-rate dependency. The influence of viscosity on loading rate effect of dynamic tensile strength is validated，but they are not positive correlated. The energy of stress wave propagation in the sample attenuates with the sandstone viscosity under the low loading rate. So the crack initiates at the center of Brazilian sample and propagates along the loading diameter，but the sample is not separated into two halves. The position of crack initiation at the center of sample is thus validated.

The seismic quality factor is commonly used to describe the attenuation characteristics of stress wave propagation across rock masses. In order to research the influence of Joint Matching Coefficients(JMCs) on the seismic quality factor Qs of jointed rock mass，a series of uniaxial impact compression experiments were conducted on the granite specimens containing artificial joint by using the apparatus of split Hopkinson pressure bar(SHPB). A method to calculate the seismic quality factor is proposed based on the variation of stress wave energy and conformed to the concept of seismic quality factor. The method is proved to be equivalent to the stress-strain method on the condition that the stresses on the specimen are uniform. The stress-strain curves were calculated through the three-wave method，while the seismic quality factor of the specimen was calculated with the energy method. The experimental results show that both the dynamic secant modulus and quality factor decrease with the decrease of joint matching coefficient，indicating that a joint with smaller contact area weakens the whole specimen，but enhances the ability of energy dissipation.

Hypabyssal rock is a special material with the property between rock and soil. Few researches have been conducted on the mechanical properties of hypabyssal rock. In this study，a field test device for conducting the load carrying tests and the shearing tests simultaneously was designed. The load carrying test of fine sand hypabyssal rock and the shear test on cementation surface of concrete and fine sand-hypabyssal rock were conducted at the south anchorage base of Maputo bridge. The load carrying and shearing parameters of the fine sand-hypabyssal rock are obtained. Based on the obtained parameters，the prediction of deformation modulus of hypabyssal rock and the morphology and mechanism of shear failure of cementation surface were further studied and discussed. The bearing property of hypabyssal rock was found to be similar to rock. The empirical methods based on the on-site geological conditions can be used to estimate the deformation modulus accurately. However，the shear property of the cementation surface is different from the rock. Its low compactness leads to the strong cementation with the concrete and form an obvious adhesive zone. The cementation should be fully considered when the shear strength of the hypabyssal rock-concrete cementation surface is evaluated. 

Gangue rib control is one of the biggest challenges for gob-side entry retaining formed by roof fracturing in thick coal seams. In this paper，the mechanism and control techniques for gangue rib deformations were systematically investigated using theoretical analysis，numerical simulation and field experimental methods. First，mechanical and numerical models were developed respectively to explore the dynamic impact behaviors of the gangue body for different mining heights. Based upon the obtained results，a multi-level control approach was proposed to address the instability problem of the gangue rib in thick coal seams. The results indicate that as the mining height increased，the impact force acted on the gangue prevention structure increased accordingly. The intense impact of the gangue body initiated the deformation of the conventional gangue prevention structure，and the roof sagging accelerated further its failure process. The severe impact area was within 6 m from the active mining panel，and an impact prevention device was designed to dissipate the impact energy. The variation of the lateral pressure was gentler within the compression area of the gangue rib. An individual support structure of sliding-type characterized by pressure release was designed and tested. Laboratory tests showed that the sliding-type structure coordinated effectively with the roof deformation，and thus improved massively its recycling utilization ratio. The anchor bolt of wave-type with multi-resistances was invented to further improve the monolithic stability of the gangue rib. Field pullout tests proved that the reinforcement effects of the structure were remarkable，especially when the structures were 60 m or far behind the active mining panel. The monitored results showed that the rib deformation decreased by appropriately 72% and the damage rate of the gangue prevention structures reduced by appropriately 85% after adopting the new approach. The proposed approach not only solved the rib control problems，but also brought about remarkable economic benefits.

A stress path model with the subloading surface based on the Drucker-Prager yield criterion and the subloading surface theory was established to reflect accurately the response of rock under the action of earthquake. A dynamic constitutive model of rock material was proposed considering the rate effect of elastic modulus and strength. The proposed model was applied to the Xianglushan tunnel. The results show that the stress path model describes the Masing effect and the ratchet effect of basalt better than Drucker-Prager criterion under cyclic loading. When the rate effect is not taken into account，the slope of the stress-strain curve is smaller than that of test curve and the cumulative strain is larger than that of test curve. In the process of cyclic loading and unloading，the dynamic modulus obtained with the dynamic model is larger than that from the stress path model with subloading surface and the deformation obtained with the dynamic model is smaller than that from the stress path model with subloading surface. Therefore，the proposed model reflected well the dynamic mechanical properties and deformation properties of the rock. In comparison with the results from Drucker-Prager criterion， the instantaneous relative peak deformation between the left and right monitoring points of the tunnel from the dynamic model increased 0.67 cm，and the permanent relative deformation between the bottom and top monitoring points and between the left and right monitoring points are increased 0.19 cm and 0.77 cm respectively. This indicates that the dynamic model reflected better the large deformation of the surrounding rock. The dynamic model of rocks is more effective in filtering the high frequency than Drucker-Prager criterion and linear elastic constitutive.

Rock burst is a key problem in the engineering construction. An accurate forecast and assessment of rock burst risk is crucial. The actual rock burst occurred in the deep buried tunnel group of Jinping II with 7 tunnels of different diameters and total length more than 16 km. The rock burst tendency test was carried out and the stress condition，stress path，energy storage depth and releasing energy were investigated. The test of rock burst tendency is based on the mechanical properties of rock in small scale，which is difficult to reflect the influence of geostress on rock burst risk，so the method has some limitations. Accordingly，the stress and the energy analysis method are able to reveal accurately the problems of size effect. The results based on the mechanical characteristics，the stress path，the energy storage capacity and the energy releasing analysis of deep buried marble show that the drainage tunnel of 7 m diameter has a higher risk of rock burst than the traffic tunnel of 6 m diameter and the diversion tunnel of 13 m diameter. This proves that there is no linear relation between the rock burst and size. According to the actual statistical data，the ratio of rock burst and the proportion of strong to super strong rock burst of the drainage tunnel are also higher than those of the traffic and diversion tunnels. The frequency and intensity of rock burst of the traffic tunnel and diversion tunnel are in the same level，and the result is consistent with the theoretical analysis.

In practice，the bending moment and axial forces in the longitudinal direction of shield tunnel may exist simultaneously. The traditional method evaluating the equivalent bending stiffness under the conditions of pure bending may bring errors. In this paper，5 kinds of bending modes have been proposed to consider the combined effect of axial force and bending moment on longitudinal bending deformation. Furthermore，a model calculating  the longitudinal equivalent bending stiffness of shield tunnel was established based on the classical SHIBA model. A computer program was written for the implementation of the model. The shield tunnel of Metro Line 3 in Chengdu as was analyzed. The practical method of determining the bending modes was discussed, the critical bending moment in deformation process，and the internal force condition of linear or nonlinear bending deformation were given. The results show that the process of longitudinal deformation of shield tunnel with bending moment can be divided into four categories according to the axial forces. The development of the equivalent bending stiffness and the opening of segment ring are very different. The axial forces has a significant effect on the equivalent bending stiffness，generally，the compression bending >> pure bending＞stretch bending.

The experimental study on the bearing capacity of heat-exchange piles in saturated clay in Ningbo was carried out under the conditions of 28 ℃，28 ℃→55 ℃，28 ℃→55 ℃→28 ℃. Heating (cooling) was carried out on the pile and soil firstly，and the static load test was then carried out to measure the temperature and pore water pressure，surface subsidence and displacement at pile top，axial force of pile and load-settlement data. The process of thermal consolidation and the mechanism of negative friction are investigated. Secondly，based on the model test，the finite element model for pile-soil considering the thermo-hydrodynamic coupling effect is established using software Abaqus. The calculated results are compared with the experimental results. The influence of temperature on the axial force and pile side friction of pile is discussed. The results show that the expansive deformation occurs in the pile and soil after heating，and the excess pore water pressure appears in the soil. With the dissipation of the pore pressure，the phenomenon of consolidation upon heating occurs in the soil，the settlement of soil is larger than that of the pile，the soil settlement takes place，and the negative skin friction resistance occurs because of the dragging load at the side of pile. With the increase of temperature，the strength of the pile is weakened along the depth direction，the strength of the soil after the heating consolidation is increased，the friction resistance of the pile is increased and the ultimate bearing capacity of the single pile increases with the temperature.

The drying-induced micro-structure evolution of reconstituted Jossigny silt that contains 34% clay-sized fraction was investigated through mercury intrusion porosimetry tests on samples with different water contents. During the preparation of soil samples，the macro-cracks were avoided as far as possible. The final cumulative intrusion void ratio decreased upon drying and became almost unchanged when the water content was lower than the shrinkage limit. The inaccessible pores increased and reached a stable state during drying. The pore size distribution(PSD) curve was shifted left to smaller diameter. However，further drying led PSD curve to shift right to larger diameter，which represented the special microstructure evolution in silty soil during drying because of the microstructure composition of silty soil. Moreover，a bump in PSD curves at the diameter range from 0.1 to 1 ?m indicated the possible occurrence and development of the internal micro-fissures. Once the silt slurry was dried to unsaturated state，the microscopic fissures might begin to develop in the clay fraction that coated the silt grains and in the interface between the silt grain and clay particles. These internal micro-fissures identified in the residual shrinkage stage are different from the macro-cracks due to desiccation.

An integration scheme based on the fully implicit Euler algorithm of backward integration has been proposed for a bounding surface model of unsaturated expansive clay. Two plastic deformation mechanisms in the modeling are defined，i.e. the loading-collapse mechanism and the microstructure mechanism. The coupling of stress-strain behavior to the hydraulic hysteresis is taken into account. Various situations are defined in a stress integral process according to the current stress state and the number of irreversible mechanisms active for mechanical modeling and hydraulic modeling. The trial solution is obtained by the Euler backward integration algorithm for each situation，and the true one is determined according to defined criterions. The performance of the model and the integration scheme were verified through the simulation of a series of published tests，including the cyclic suction tests and the triaxial tests. The stability and accuracy of the integration scheme are demonstrated through the comparisons of the calculated results of strain controlled tests for unsaturated expansive soils with different step sizes.

The ranges of coefficient of subgrade reaction in different soil layers and the relationships of coefficient of subgrade reaction with depth are analysed based on the measurement with plate load test in Xi?an Metro. The measured coefficients of subgrade reaction from the  plate load test，the pressure-meter test，the standard penetration test，and the laboratory consolidation test are compared and analyzed with the method of regression analysis. The results show that the coefficients of subgrade reaction of the new loess layer，the old loess layer and the paleosol layer increase with depth，but the variation regularity is not obvious in the loess-like soil layer. The horizontal coefficient of reaction is mostly smaller than the vertical coefficient of subgrade reaction . In general，the ratio  exhibits a normal distribution. The values of of nearly 81% of the total test data are distributed in the range 0.5–1.0. The measured coefficients of subgrade reaction vary linearly with the pressure-meter modulus and the SPT counts. The measured coefficients of subgrade reaction have approximately the quadratic relationships with the modulus of compressibility and the coefficient of compressibility.

The over consolidation ratio(OCR) is an important parameter to evaluate deformation and strength characteristics of soil. The consolidation states and formation mechanism of the soft clay were analyzed based on the field vane strength of soft clay at six coastal areas in Tianjin，Shanghai，Lianyungang，Shenzhen，Zhongshan and Zhuhai. It was found that the OCR obtained from the field vane tests(FVT) was much larger than that obtained from the one-dimensional compression tests in laboratory and that the laboratory tests significantly underestimated the OCR of these soft clays. The variations of OCR with depth for these six areas are very similar and the OCR decreases to a stable value at a certain depth. The shallow soil shows over consolidation，but the deep soil shows some complexity. It was also found that Hanzawa and Tanaka?s model can explain the formation mechanism of over consolidation and the variation of OCR with depth. The over consolidation of shallow soils originates mainly from the complex“surface effect” of cement or weathering，while the over consolidation of deep soil is due to the secondary compression. Considering the considerable sampling disturbance，this method based on FVT for evaluating OCR is worthy of recommendation for Chinese coastal areas.

Changes of air temperature or rainfall will inevitably influence the embankment stability in permafrost regions. Previous studies focused mainly on the influence of air temperature on the thermal stability of the embankment，while the influences of rainfall on the embankment and the influencing mechanism have not been fully considerated. Moreover，the understanding on the role of rainfall is still controversial. Observed data showed that the rainfall increased significantly on the Qinghai—Tibet Plateau during the past 50 years. The increase in rainfall can result in the change of the thermal-moisture activity in the active layer，the near-surface energy and the mass budget. The in-site precipitation and moisture data within railway embankment been measured in Beiluhe permafrost station and the water-vapor-heat transport model established were used to predict the process and mechanism of influence of increasing rainfall on gravel embankment. Collected data indicated that rainfall in summer significantly affected the shallow moisture in short time. But the long-term water content was not affected by rainfall, the moisture evaporation and the liquid water and water vapor transfer in embankment occurred clearly. The increase in rainfall will increase the surface latent heat，lower the heat flux and temperature of surface soil，and raise the artificial permafrost table. The reduction of heat conduction caused by increased rainfall is greater than the increase of heat convection of liquid water. Therefore，the increase in rainfall can mitigate the process of permafrost degradation and will alleviate the thermal influence of embankment engineering on underlying permafrost. While，the increased rainfall infiltrations will result in the increase of water content in embankment and induce the frost heave and thawing settlement.

In order to effectively detect the hidden faults of the retaining structures of deep foundation pit and ensure the safety of foundation pit，a theoretical model for the detecting range of the micro-well logging were deduced based on the theory of electrode tube detection. The numerical simulation on the detection of transverse cracks and longitudinal cracks were carried out with methods of AM and AMN. The results show that the perceiving ability of AM to transverse cracks is greater than that of longitudinal cracks，the perceiving ability of AMN to longitudinal cracks is greater than that of transverse cracks. The influence of electrode tube distance，the electrode pole distance and crack size on the sensitivity of micro-logging electric detection were analyzed. The results show that the sensitivity of AM device is mainly related to the electrode pole distance and the width of the cracks to be measured，while the sensitivity of the AMN device is mainly related to the electrode tube distance and the lengths of the cracks to be measured. The general requirement of parameter setting is put forward according to engineering practice. The reliability and accuracy of the micro-well logging theory in the seepage detection of the wall were verified through the physical simulation and practical application. The equivalent simplification of the testing process was realized.