Based on moisture balance of bio-slope-engineering system，the fundamental requirements of water storage capacity of root layer soil in rock slope protection are put forward. By field rainfall tests，the regulations  of moisture migration in bio-slope-engineering system for rock slope are studied. Then，the factors governing moisture balance of bio-slope-engineering system are analyzed，such as initial water storage capacity of root layer soil，vegetation interception，slope surface runoff，slope angle，slope surface evapotranspiration，and wilting capacity of root layer soil. It is shown that carrying soil can obtain larger water storage capacity in a relatively short time if its ratio is reasonable and its permeability is good，and adding a good amount of water retention agents and peats into carrying soil can significantly reduce water evapotranspiration；furthermore，water retention agent can reduce wilting capacity of carrying soil，thus more moisture in carrying soil becomes available for plants. It is also shown that vegetation interception cannot be ignored in a good vegetation-covered slope，and slope angle should be appropriately determined to improve the rainfall infiltration. The results may be helpful for moisture balance and bio-slope-engineering system control for rock slope.

Loess is a typical structured soil，and its strength is closely related to the characteristics of soil structure. The stability of working face is significantly affected by the shield construction parameters in loess strata. Soils around the working face tend to become loose and even collapse if the earth pressure is not properly controlled，which would lead to problems of tunnel structure safety and surrounding environments. Focusing on Xi?an metro line 2(the first metro constructed in loess strata in China)，the paper carried out laboratory test to study ground disturbance induced by shield tunneling and the relationship of the shield construction key parameters in loess strata using the independently designed earth pressure balanced model shield machine. Also，the ground loss ratio K and width parameter of surface settlement trough i in loess strata are obtained. The results show that the shape of settlement curve in transverse section caused by shield tunneling in loess strata is different from that in cohesive soil，which shows the curve is deep V-shaped in lower part and palliative peviform in upper part. The development of surface settlement is mutable and three stages can be observed. The change of thrust force leads to the change in earth pressure directly，and the earth pressure and unearthed rate are somewhat randomly distributed. The unearthed rate has a decrease trend with the increase of thrust force，whilst there is an inversely-proportional relationship between advance speed and unearthed rate.

In order to understand the uplift bearing mechanism of a new-developed grouting-screw uplift pile，experimental investigation of mechanical behaviors of the pile-soil interface was carried out. A large-scale self-developed shear apparatus is used to measure the shear stress-displacement of pile-soil interface and to observe the corresponding failure mode. Experimental results show that the non-screw pile-soil interface generates a failure plane，whilst the screw pile-soil interface produces an arch-curvature failure surface. The screwing effect on the pile-soil interface behavior leads to an increase in cohesion and shear resistance. There exist some critical interval spaces between the two neighboring screws，where the largest arch-curvature failure surface is reached and the maximum soil-pile friction resistance is activated.

Ground settlements and underground structure deformation induced by subway tunneling are hot issues in the underground transportation construction safety control and risk assessments. Previous researches on ground settlements are basically concentrated on the soil free displacements，and the sheltering effects of adjacent existing underground structures are not considered. Based on the Shanghai tunneling case，the ground settlement rules induced by earth pressure balance(EPB) shield considering sheltering effects of tunnels in service are presented by using simplified analytical method，3D finite element(FE) numerical simulation method，and in-situ monitoring method. An in-depth analysis is conducted between ground settlements considering sheltering effects and those considering free soil displacements. In addition，the predicted deformation of subway tunnel induced by EPB shield during complex overlapped traversing process is also presented. It is observed that the simplified analytical method and 3D finite element method can perfectly simulate the ground movements induced by subway shield excavation considering sheltering overlapped effects. Furthermore，the sheltering effects have a major influence on ground settlements induced by EPB shield when the tunnels are excavated in the vicinity of existing buildings and structures. The differences compared with the results considering free soil displacements are obtained. Finally，the deformation controlling technical measures considering sheltering overlapped effects are proposed in combination of in-situ monitoring data. It may provide certain basis to build up correctly protective measures of geotechnical environments influenced by subway tunneling，especially the sites adjacent to existing buildings and structures.

以国道318线黄草坪2#隧道为原型，开展大型三维振动台模型试验，重点研究隧道结构的地震动力响应规律及隧道与围岩的相互动力作用。通过对模型试验的关键技术研究，建立一套山岭隧道大型振动台模型试验设计、制作、加载及测试的工艺与方法流程。模型震害分析表明：隧道洞口边坡以开裂和滚落石震害为主，坡面加速度沿高程方向递增且具有一定的放大效应，在坡面原生裂缝和薄弱部位极易出现震害；隧道结构以衬砌开裂和掉块震害为主，初期支护和二次衬砌出现裂缝的部位不同，但钢筋网能够有效地阻止裂缝的发展。模型试验结果表明：隧道结构的加速度响应要大于周边围岩且对周边岩土体的加速度响应有一定的放大效应；对于一般的硬岩质山岭隧道来说，隧道洞口段0～50 m范围的加速度响应较大，为隧道抗减震设防的重点区域；山岭偏压隧道横向不同部位的地震动力响应存在明显差异；当地震波从隧道底部小角度入射时，隧道结构的加速度响应最强烈，对隧道结构的安全性是非常不利的；随着加载地面峰值加速度(PGA)的增大，隧道不同部位的加速度响应增大，但当隧道结构进入非线性破坏状态后，PGA呈减小趋势，地震能量逐渐被耗散。

In order to investigate the rainfall infiltration effects on working characteristics for the bedding rock slope with weak interlayer，model tests have been conducted combining superimposed spraying rainfall and fiber Bragg grating(FBG) monitoring technologies. Physical characteristics，including displacement and water content，have been studied aiming at bedding rock slope with different bedding angles and with and/or without supporting. The results show that，displacement of bedding rock slope with weak interlayer shows steep-variant and pull-type without supporting；while with supporting it shows slow-variant and push-type. At the same time，due to the interlayer dislocation phenomenon with the increasing of bedding angle， displacement monitoring in depth should be considered especially with the bedding angle larger than 35°. The weak interlayer mudding phenomenon is also observed in test and the location lay in the front of the without supporting bedding slope while it lies on the back of the supported bedding slope. With the continuing rainfall infiltration，the anti-slide force is changed from providing shear resistance of bolt to providing pull resistance of bolt. The test results can provide some advices to design and monitoring of similar slopes.

Based on the chemical-physical combined method(CPCM) to more efficiently increase consolidation effects of soft clay or clay slurry and incorporated with the advanced vacuum preloading(VP) technique with vertical drains，new lab testing results of three-dimensional consolidation on the chemically treated Pearl Rivel marine clay under VP were presented；while parallel tests with pure marine clay under VP were conducted. The testing results show that the consolidation rate of the models using CPCM is obviously faster than that using conventional VP method. Within the same consolidation time，the compressive strength of the consolidated soil achieved by CPCM is much higher than that achieved only by applying VP. Furthermore，the similar tests conducted on Singapore marine clay also supported the findings that CPCM has super effectiveness and advantages. This totally new CPCM has therefore high development potentials for both academic research and engineering application especially in land reclamation.

A consensus about the understanding of groundwater effecting on tunnels is not reached yet up to now，and the impact of groundwater pressure on supporting structure was not fully understood. Based on this，model tests are carried out to understand the effects of water pressure on tunnel. In a 300–350 km/h high-speed railway project，the design of model test included simulated rock，test fluid，material parameters，test conditions，test equipment. In this test，various working conditions were considered，such as 1 m，2 m and 4 m water heads without supporting and with free drainage，lined with undrained condition. With the testing results，a relatively clear understanding was obtained，i.e. the changing process of groundwater seepage caused by tunnel excavation and shoring，the correlation between water load and groundwater discharge methods. Furthermore，numerical simulations were performed based on the model test results.

A water diversion tunnel is located in the soft surrounding rocks，and double composite linings are employed during tunnel structure. In order to reveal the mechanical properties of such prestressed double composite linings，the 1∶1 simulation model test and 3D nonlinear finite element method are used. The test processes，including segments assembling，earth filling by layer，inner lining casting，pretension of inner linings，and applied water pressure，are simulated in sequence in the finite element model. Besides，the coupling effects of lining and earth are also taken into consideration. The earth parameters are determined by back analysis method with the displacement of outer lining. The contact between the assembled segments and the inner or the outer lining is also simulated by contact algorithm based on direct control method. The results of finite element method match well with test results，such as displacement and stress of structure，opening of gap. Furthermore，the seepage rise is discussed and corresponding measures are proposed. The results are helpful for the design of similar engineering projects.

Horizontal bearing characteristics of bridge pile foundations can be analyzed by using linear elastic subgrade reaction method(m-method) when displacement of pile foundation is generally smaller. However，displacement of pile foundations is often larger under the effect of strong earthquakes. In order to understand the horizontal bearing capacity and deformation characteristics of pile foundations considering nonlinear behaviors of pile shaft and subsoil，a model of pile foundations is constructed. Failure mechanism，bearing capacity，deformation characteristics and hysteresis characteristics of pile foundations are studied by using pseudo-static test. A nonlinear static calculation model of pile group foundations is put forward under horizontal load. The elastoplasticity of pile shafts in variable axial loads is simulated by distributed PMM plastic hinge；and nonlinearity of subsoil is simulated by the curves of p-y，t-z and q-z，respectively，which have been given in the code of American API；where p is horizontal soil resistance at lateral of pile shaft；y is horizontal displacement；t is vertical frictional resistance around piles shaft；q is vertical bearing resistance at pile tip；z is vertical relative displacement of interface between pile and soil. The results show that：(1) The numerical results are in good agreement with those obtained from experiments. (2) Hysteretic characteristics of pile foundations can be simulated using Clough degradation bilinear model. (3) Weak positions of pile shaft are 0–4 times around the radius of pile below pile top. The results can provide references for evaluating seismic performance of bridge pile foundation using capacity spectrum method.

For the large-diameter cast-in-place concrete bored piles in low-temperature permafrost ground，a large amount of heat produced by concrete hydration would result in thawing of permafrost soil around the pile，and thus the interface between the pile and the soil would not have enough freezing strength，making it impossible the pile to reach the designed bearing capacity at an early stage after the construction. Thus，the bearing and deformation features of the piles under a non-refreezing state were studied. A series of in-situ ground temperature tests and static loading tests were performed for the pile foundations of the Sonam Dargye Bridge located at the Qinghai-Tibet railway during its construction. The pile-soil-surface thermometer holes，pile-side thermometer holes(30 cm from the pile skin) and reference thermometer holes to measure the ground temperature undisturbed by construction，denoted by SB，SC，and JZ，respectively，were set up to obtain the corresponding temperatures. The temperature distributions for the pile-soil system at various ages were obtained when the piles were cast in summer and the initial concrete temperature was 11 ℃. The refreezing process of the pile-soil system as well as the distribution characteristics of the vertical bearing capacity，vertical deformation and skin friction(or freezing force) of the pile under various ground temperatures were analyzed. Test results show that 30 days after the construction of the pile，the temperature along the pile skin is negative(approximately －0.43 ℃–－1.26 ℃) except in the section 0–2 m below the ground surface；50 days after the construction of the pile，it becomes a bit lower(approximately－1.0 ℃–－1.85 ℃). Compared with the original undisturbed state，the pile-soil system is not fully refrozen. When a maximum vertical load of 7 600 kN is applied，the vertical pile-head displacement is 4.93 mm while the residual deformation after unloading is 1.01 mm. It shows that the pile has a high vertical bearing capacity and a small deformation under a non-fully refreezing condition with the pile age of 30 days.

In order to verify the applicability of red mudstone as subgrade filling in Dazhou—Chengdu railway，laboratory dynamic triaxial tests and field cyclic loading tests were performed. The dynamic strength and deformation properties of red mudstone were investigated by the dynamic triaxial tests. After introducing the concept of dynamic stress level，the test results indicate that the critical level of dynamic stress is about 30%. By analyzing the correlation between dynamic shear stress ratio and accumulative deformation，this paper proposes a calculation model of accumulative deformation of red mudstone subjected to cyclic loads，and presents the physical meaning and determining method of model parameters. The results of field cyclic loading tests demonstrate that settlement and rate of subsidence of subgrade can meet the requirements of high-speed railway construction when using red mudstone to fill the base layer of subgrade bed. Employing the proposed prediction model to calculate the accumulative deformation of red mudstone layer，the calculated and measured values match well as the deformation is stable；but some differences are observed before deformation stability due to different conditions and loading frequencies between laboratory and field tests.

In order to mitigate the environmental impacts in terms of high energy consumption，CO2 emissions and no-renewable resources consumption associated with Portland cement(PC) soft soil stabilization，the stabilization effect of alkali-activated ground granulated blast-furnace slag(GGBS) for Lianyugang soft soil was investigated through laboratory test and then it was compared with that of PC. The results show that the Na2CO3-activated GGBS had the minimum stabilization efficacy for this soft soil. NaOH-activated GGBS stabilized soil had the highest unconfined compressive strength(UCS) at 7，28 and 90 days，however its UCS decreased after 90 days. The GGBS-carbide slag stabilized soil had lower 7-day and 28-day UCS than that of PC mix，whilst the former had much higher 90-day and 180-day UCS than the latter. The Na2CO3，NaOH and Na2SO4 could accelerate the strength development rate of GGBS-carbide slag stabilized soil. The Na2CO3-activated GGBS-carbide slag stabilized soil had only slightly higher 7-day，28-day，90-day UCS and lower 180-day UCS than those without Na2CO3. NaOH significantly increased the UCS of GGBS-carbide slag stabilized soil at 7，28 and 90 days. However the UCS decrease was observed from 90 days to 180 days. The Na2SO4 had the highest activating efficacy for GGBS-carbide slag stabilized soil，and thus was suggested to use in practice due to both the economical and environmental benefits.

Residual strength of slip zone soil is the major concern of slope engineering. There is a close relation between microstructure of the shear surface and the strength. Ring shear tests are performed on the clay samples (containing sand) that were obtained from an ancient landslide slip zone. The scanning electron microscope is used to analyze microstructure of shear surface and its relationship with strength. Unlike most clay，the shear strength of the investigated slip zone soils exhibits a slight strain-softening，and increasing coarse fraction significantly influences the post-peak strength. Micro characteristics of shear surface show that the shearing process resulted in directional arrangement of particle and microstructure change，followed by coarse particles broken，void ratio increased and particle shape narrowed. Besides，fractal study of the particle by the perimeter-area method reveals that the particle form has a strong fractal feature，suggesting a good negative linear correlation with residual strength.

The undersea tunnel of Zhoushan Putuo District Shenjiamen Harbor in north shore is constructed by the way of open excavation. Shenjiamen Harbor is located in shallow sea area. At the beginning of construction，sand soil cofferdam was used to cut off sea water. Monitoring data show that sand bag used in silt soil is susceptible to water erosion of sea water tidal fluctuation and water level change，which will cause large deformation. The maximum settlement and horizontal displacement are 74.1 cm and 216.6 cm，respectively. The safety factor of cofferdam calculated by Bishop method is not satisfied，adjustment of the cofferdam should be made based on field monitoring and calculation. However，when the steel pipe pile was introduced to the cofferdam，settlement and horizontal displacement are effectively controlled. The results provide a reference for the construction and design of geomembrane bag with sand soil cofferdam in deep foundation of undersea tunnel under conditions of coastal muddy land.

A non-coupling method is used to simulate the pore pressure accumulation in surrounding soil induced by pile vertical vibration. Firstly，an analytical solution of steady-state pore pressure built up by vertical vibration of a floating pile in saturated soil is obtained based on Biot?s theory of saturated porous media，considering the imperfect bonding condition at the contact surface of pile and soil in the course of pile sinking. A semi-analytical solution of transient pore pressure oscillation is deduced by using a convolution method and a numerical integration technology of the inverse Fourier transform under arbitrary sinusoidal excitations. Then according to empirical formula of residual pore pressure of saturated silty clay obtained from dynamic triaxial test，a connection between the steady pore pressure and the residual pore pressure is established in terms of shear strain and excitation times. Furthermore，the simulation of pore pressure accumulation of surrounding soil aroused by pile vertical vibration is successfully achieved. Numerical results show that the steady-state pore pressure distributions and pore pressure accumulations in the imperfect bonding condition are smaller than the ones in the perfect bonding conditions. The contact stiffness between pile and soil and the rigidity at pile toe have significant effects on them. Besides，the permeability coefficient of soil has obvious effect on steady-state pore pressure distributions.

The oil storage tanks of the Terminal Oil Station in Lanzhou are the first large oil storage facilities built on saturated loess ground in China. Cement-flyash-gravel(CFG) piles were adopted to improve the foundation due to its low bearing capacity of approximately 60 kPa. Based on a oil storage tank of 15×104 m3 in volume，experimental study was performed to explore the bearing and deformation features of the CFG-pile composite ground. Soil pressure cells，pore water pressure gauges and settlement meters were installed in the CFG-pile composite ground. Field testing results show that the bearing capacity of the CFG-pile composite foundation reaches 275 kPa. The water filling test of the tank reveals the varying processes of the pile stress，soil stress，pore water pressure，ground settlement and the deformation of the tank's circular foundation. It is indicated that the maximum settlement of the tank's circular foundation is 30 mm while the minimum settlement is 11 mm. The maximum differential settlement of the tank in the diametral direction is 16.0 mm；the maximum nonplanar tilting rate of the tank in the circumferential direction is 0.002 46. The ratio of the pile stress to the soil stress rises as the load increases and reaches 12.6 under the maximum test loading；the soil reaction distribution at the tank bottom takes on a V-shape in the radial direction. The results show that it is effective to improve saturated loess ground by CFG pile.  

Considering the complexity of underground engineering geological conditions and the uncertainty of risk，a risk evaluation methodology was put forward to realize quantitative assessment based on attribute mathematical theory. The value of evaluation index is an interval rather than a certain value，which is the core of the proposed method differed with other methods. A new method and its applications were proposed for synthetic attribute measure analysis and attribute recognition with an engineering case. Seven major influencing factors of water inrush in karst areas were selected as the evaluation indices and the index system of water inrush risk assessment was constituted，and a corresponding evaluation model was established. Comprehensive assignment method was applied to analyze the weights of evaluation indices. The water inrush risk of one tunnel was evaluated by using the established model，and comparisons of the results derived from the proposed method and attribute mathematical method were made. The results indicate that the evaluation results are basically in a good agreement with the observed results，which verify the rationality and feasibility of the proposed method. The risk assessment methodology can provide a powerful tool for quantitative assessment of water inrush in karst tunnels.

The loading rate effect is an important property of rock materials. The research of the Brazilian splitting test at different loading rates on the hard brittle marble in depth in Jinping II hydropower station shows five characteristics：(1) The failure processes can be almost divided into four steps regarding the loading rates，i.e. stress concentration zones，expanding of the stress concentration zones，shaping of the failure and failure. (2) The peak stress in the Brazilian splitting test logarithmic increases with the increase of the loading rate. (3) The loading rate is higher，the average vertical strain is greater，but the average lateral strain is smaller. (4) According to the fractography，the analysis of the microcosmic fracture surfaces shows that the area of mirror district at the rate of 2.55 MPa/s is less than that a of 0.000 255 MPa/s and the shear failure is dominant；furthermore，the sawtooth district of the 0.000 255MPa/s is regular. (5) At the rate of 2.55 MPa/s，the sample breaks into more pieces and the failure is much more violent than that at a lower loading rate. The energy of sample failure at the rate of 2.55 MPa/s is greater than that at the rate of 0.000 255 MPa/s when calculation. The test result is analyzed in view of macroscopic and microscopic studies；and fractography is utilized to explain the mechanism of the rock failure at different loading rates. The analysis method is helpful for the understanding the loading rate effect and its mechanism.  

The calculation formula of frost-heave ratio of saturated rocks is modified according to experimental results of rock frost-heave ratio. The possibility of frost-heave of saturated fracture is analyzed and the corresponding linear frost-heave ratio is given. Calculation formula of frost-heave ratio of rock mass is achieved，assuming that the distribution of rock fracture morphology is layered. The frost-heave ratio of various lithological rock masses of different grades in open system is calculated. In the open system，the frost-heave ratio of rock mass has the following characteristics. For non-frost-heave susceptible rocks，frost-heave is mainly caused by the freezing of field water in the pore or fissure，the larger porosity or cranny ratio of rock mass will induce bigger frost-heave ratio. For frost-heave susceptible rock，frost-heave is roughly affected by the water migration during freezing：the more the water migration is，the bigger the frost-heave ratio is. With the increase in surrounding rock grade，cranny ratio of rock mass increases，and also the frost-heave ratio of the rock mass increases. The frost-heave ratio of frost-heave susceptible rocks increases faster than that of non-frost-heave susceptible rocks. In addition，the frost-heave susceptibility of rock mass is classified，considering the effects of frost-heave susceptibility of rock and fissure filling，grade of rock mass，rock porosity，and groundwater recharge conditions. The frost-heave susceptibility of surrounding rocks of three tunnels in cold regions is evaluated using the proposed method. The cost of the tunnel can be reduced by choosing proper support parameter according to site-specific frost-heave susceptibility of rock mass.

The rock dilatancy-bulking deformation characteristics under high geostress unloading condition are critically important to understand the stability evolution and control mechanism of deep roadways，and to evaluate the stability of surrounding rocks. Using the triaxial unloading tests on the rocks sampled from the Gubei colliery，the evolution characteristics of the typical stresses with confining pressure are first studied. The criterion of rocks approaching pre-peak damage dilatancy and post-peak bulking deformation under critical condition is proposed. Then，the damage and degradation process of mechanical parameters of rocks during unloading are considered，and a progressive failure constitutive model is subsequently constructed. Finally，the distinct element code UDEC is embedded into the model to realize nonlinear numerical calculation. Simulation results of triaxial unloading tests show that the proposed model is suitable for describing the rock dilatancy-bulking deformation characteristics. Besides，the proposed model is used to evaluate the excavation damaged zone(EDZ) around a deep roadway. Compared with classical Mohr-Coulomb strain softening model，the performances of the proposed model are suggested to be applicable for practical engineering，and helpful for stability analysis and maintenances of deep roadways.

A comprehensive gas-flow model for shale gas reservoir is significantly important for the dynamic analysis of gas production and reservoir simulations. This paper proposed a hydro-mechanical model for shale gas reservoir that was considered as dual permeability media of matrix pore and fracture. The Knudsen flow in porous matrix and Darcy flow in fracture network were assumed. The model involves multiple flow regimes，gas adsorption/desorption，and stress-sensitive effect. Finite element method was used to discretize the governing equations by fully implicit discretization schemes，and thus corresponding code was made. A numerical example was presented using the proposed model and field shale parameters. Results show that the pressure-declined rate of shale gas reservoir is less than that of conventionally fractured reservoirs. Fracture permeability is a primary factor of reservoir pressure depletion. It is necessary to make the flow conductivity of fractures match with the gas production from shale matrix. The initial pressure has a major effect on the fracture pressure depletion，which indicates that the less initial pressure is，the less fracture pressure depletion is. The presented model and code are helpful for understanding shale gas production and developing the shale-gas reservoir simulator.

Transverse deformation is basically regarded as a key index to evaluate structural behaviors of shield tunnels. The joint stiffness in shield tunnel is always weaker than segmental lining. Therefore the transverse deformation of shield tunnel is mainly governed by opening of joint and rotation of segmental lining. This paper presents a deformation sensing method using two-point fixed pretension fiber based on distributed optical fiber sensing technology，i.e. Brillouin optical time domain analysis(BOTDA). Both the spatial resolution of analyzer and the pattern of transverse deformation of shield tunnel are considered in this method. Geometrical analysis is used to calculate the opening of joint，rotation of segmental lining and deformation of tunnel. Two laboratory segmental joint tests of full-scale shield tunnel with different axial loads are conducted to verify this method. Test results indicate that this method is efficient in sensing the deformation of shield tunnel. Furthermore，monitoring density of shield tunnel deformation can be significantly increased using this method. Using this long-distance，high-density，high-accuracy and low-cost healthy monitoring method，the safety of metro tunnel operation can be greatly ensured.

Shangbai large cross-section tunnel in Datong-Xi?an Passenger Dedicated Lines passes through dry fine sand layers. Its construction technologies are difficult and risky. Through the comparative field experiments of close-packed small pipe and deep secant pile of pre-reinforcement，it is found that the deep secant pile pre-reinforcement scheme can effectively control the quick sand and sand gushing during the tunnel excavation. Meanwhile the physico-mechanical parameters of the fine sand layers and consolidation body are obtained by deep secant pile test through laboratory tests，including direct shear tests，triaxial tests and unconfined compression tests. On this basis，through the numerical simulation and field test of tunnel excavation method in dry fine sand layers，the reasonable construction scheme is proposed. The results can provide technical support for Shangbai tunnel construction and reference for similar projects.

The microstructure characteristics of loess，especially Q2 loess，at Pucheng power plant in Shaanxi Province were investigated using Quanta environment scanning electron microscope(ESEM). Consequently，various microstructure pictures were obtained. The four forms of particle connections，i.e. direct point contact，direct face contact，indirect point contact and indirect face contact，are suggested. The microstructure quantitative analysis results of loess show the area proportion，the orientation and the distribution fractal dimensions of particles increase with depth. Whilst the area proportion，the orientation and the distribution fractal dimension of pore，and the Euler value decrease with depth. However，the number and the roundness of particle，the number of pore，and the gray entropy have not significant change law with depth. The microstructure characteristics and the collapsibility of Q3 and Q2 loesses have a good relationship.

In view of characteristics of static and dynamic uniaxial compression，such as mining rock pillar，the influence of initial mesoscopic damage level under uniaxial static compression on mechanical properties of rock specimen with a single fissure under subsequent uniaxial dynamic compression and the energy dissipation mechanism are simulated by particle flow code. Minor influence of initial damage level under static uniaxial compression on patterns of stress-strain curves of rock specimens which are under dynamic uniaxial compression subsequently is observed. The damage at pre-peak and the crack coalescence at post-peak for damaged rock specimens behave in obvious progressions and jumps. Lower strength of specimens is presented with the increase of initial damage. But the subsequent dynamic compression suggests the strength increases drastically compared with one due to initial damage. The normal and tangential fracture stresses of crack tip are reduced slightly with the increase of initial damage. And the normal fracture stress is reduced but the tangential stress increases sharply with the increase of fissure dip angle. The final macroscopic fracture mode of specimens under subsequent dynamic compression does not change around initial damage level. However，more microcracks and stronger damage localization are observed with the increase of initial damage. The energy dissipation is closely related to the mesoscopic damage evolution of rock mass. The stronger the initial damage of rock mass is，the less energy is absorbed to reach the peak failure，but more energy is dissipated at post-peak. The more dissipation energy and stored elastic strain energy at peak strength are，the stronger damage fracture at post-peak is with the increase of fissure dip angle.

To further investigate the consolidation mechanism of saturated clay，the Merchant?s rheological model is introduced. The Hansbo?s equation，described by the power function for the lower velocity of flow and the linear function for the higher velocity of flow，is employed to describe the non-Darcy flow. Accordingly，the Terzaghi?s one-dimensional consolidation equation is modified，and its numerical analysis is conducted by finite volume method. In order to verify its validity，the numerical solution by finite volume method that the flow of pore water obeys Darcy?s law is compared with the analytical solution based on the one-dimensional rheological consolidation theory in literature. The effects of non-Darcy flow and Merchant model parameters on the rheological consolidation process are investigated. Numerical results indicate that the behaviours of non-Darcy flow and the rheological effects control the dissipation rate of pore water pressure in saturated clay layers，and thereby reduce the settlement rate of these soil layers. For a given degree of consolidation，the consolidation time considering both characteristics is much longer than that considering each of them separately. In addition，the degree of consolidation in terms of settlement is less than that associated with pore water pressure when considering the rheological effect.