Experiments are performed by Metravib dynamic mechanical analyzer under sine wave loading as to imitate the seismic wave(travelling wave). The static load is fixed to 100 N，and the constant dynamic load of the sine wave is 60 N，so that the total loading force is controlled under yield stress. Temperature is controlled between －50 ℃—125 ℃，and the heating speed is 1 ℃/min. At frequency of 5—90 Hz，pump-oil saturated arkoses and Pengshan sandstones are tested under uniaxial cyclic loading. The variations of travelling wave energy attenuation，imaginary modulus，Young?s modulus and elastic wave velocity with temperature or frequency are obtained. The energy attenuation peak and the imaginary modulus peak shift to higher temperatures when the frequency increases；and the energy attenuation and imaginary peak values increase for the travelling wave. These phenomena are caused by thermal relaxation mechanism. The Young?s modulus and elastic wave velocity increase with frequency increase and decrease with temperature increase. These are obvious frequency dispersion，and the dispersion weakens when temperature decreases. The experimental results are similar to the low-frequency resonance standing wave experimental results. Thus the thermal relaxation regularities generally exist in saturated porous rocks. The results are the experimental and theoretical foundation for the study of time-temperature equivalence，and are very instructive for the study of theoretical rock physics model. This investigation is very helpful to the interpretation of seismic，acoustic wave，and seismic prospecting data.

On the basis of system analysis and summary of the existing research results of failure mode classification，analysis methods and controlling measures of surrounding rock for underground engineering，a new failure mode classification method for surrounding rock of large-scale underground cavern group is proposed. The special features such as large span，high sidewall and cross of multi-cavern influencing on failure modes have been concerned in the method. Based on the three levels：control factors，failure mechanism，generation conditions，18 typical failure modes have been summarised. The corresponding stability analysis methods and control measures are recommended for each failure modes. Furthermore，a new method is also proposed for dynamic recognition of failure modes and the corresponding control measures according to dynamic updating of geological conditions and characters of surrounding rock revealed during excavation. The new methods have been applied to dynamic construction of Jinping II hydropower station. The potential failure modes and corresponding stability analysis methods as well as control measures on excavation and support design are recommended before the construction of powerhouse. During the excavation layer by layer，the failure modes，excavation and support strategies are calibrated，recognized and modified according to the revealed actual geological conditions and characters of surrounding rocks. The procedure is continued until complete of the construction. The practice indicates that the methods are applicable，scientific and systematic，so as to provide an effective way for excavation and support design optimization during construction and avoid occurrence of local instability problems.

The applicability of spectra of bedrock earthquake motion and rationality of calculation model considering soil-structure interaction(SSI) for structural seismic response analysis are studied. Firstly，in order to obtain the spectra of bedrock earthquake motion in China，not only the expressions of the current spectra of earthquake bedrock motion are compared and the preferred one is selected；but also the high-cut filter function is modified to fit the recorded earthquake motion of target fields in China. Then，the current SSI calculation model for structural seismic response analysis is expounded essentially；and the unnegligible problem inherent in the model is pointed out. To solve the problem，the massless rigid element(MRE) method proposed by the authors to solve the problem inherent in the earthquake ground displacement input model is extended and applied to solve the corresponding problem in the current bedrock displacement input model considering SSI effect. At last，based on the works above，the program for generating bedrock displacement spectrum is coded and a soil-layers model is analyzed. The analysis results can further indicate that the MRE method is quite applicable to the calculation model considering SSI effect. The works of this paper can provide necessary reference for the relevant study of SSI effect.

Based on the results of microseismic monitoring data recorded，the law of microseismicity occurring in the deep rock masses at left bank slope of Jinping I hydropower station is investigated；and the slope stability is evaluated combining with conventional measurement data and numerical simulation using realistic failure process analysis(RFPA) approach. The following aspects are taken into consideration：(1) The evolution mechanism of micro-fractures initiation，growth and expansion in deep rock masses of rock slope is performed. (2) The internal relation between tempo-spatial distribution regularity of microseismic events and variances of multiple position extensometers in consolidation grouting tunnel #2 at the elevation of 1 829 m are interpreted. (3) The full progressive failure processes of rock slope with typical section have been reproduced. (4) The generation mechanism of cracks in the platform of dam crest at the elevation of 1 885 m is in-depth analyzed. Incorporating with site operation conditions and engineering geology，this leads to conclusions：Firstly，microseismic monitoring network installed at right bank slope could availably identify and delineate failure regions and potential sliding surface in deep rock masses. Secondly，visual deformation of rock slope and microseismicity are closely related to geological structures and grouting in the weak-layers. Finally，stress redistribution induced by high pressure cement grouting and slippage deformation of pre-existing fissure zones are the primary factors causing cracks in the platform of dam crest at the elevation of 1 885 m. The research results provide important references to the understanding and analysis of rock slope deformation and associated microseismicity-induced instability mechanism under complex stress conditions.

In the processes of landslide mass sliding and impacting on element at risk，the internal collapse of landslide mass will dissipate part of kinetic energy. But in practice，this part of energy is not taken usually into account. The discrete element method(DEM) is adopted to get impact force-time curves；and the impact energy conversion equation is also deduced based on impulse law and energy conservation law. With the analysis of the energy dissipation principle in the sliding and impacting processes of a practical rock slope，a comparison is made between the calculation method which takes both internal and external energy dissipations into account and the method which only takes external energy dissipation into account. The result shows that there is a significant difference between the two methods；and the internal energy dissipation can not be ignored. Moreover，the influence factors of impact energy and vulnerability for element at risk are both analyzed. The analysis result shows that impact energy is most sensitive to internal friction angle of landslide debris；second sensitive to distance between element at risk and landslide mass，gap length between joint segments，density of landslide mass and width of impact surface；last sensitive to the cohesion of landslide mass. In addition，the impact direction of landslide debris can simulataneously effect both impact energy and anti-impact energy.

The rock wedges under left skewback of the upstream dam line are cut by many steep faults in the dam site of Baihetan Hydropower Station. They locate at the bottom and the downstream of the arch dam. Their stable movement or not will affect the safety of dam foundation and arch dam. The safety performance of arch dam and rock wedges are comprehensively analyzed considering the complicated crack hydraulic pressure in joint planes between rock wedges，various of water pressures are programmed and the approach is validated using the conceptual model in the software fast Lagrangian analysis of continua in 3 dimensions(FLAC3D). According to the results of calculation and the displacement of the selected typical nodes，the stability safety degree，surface safety factor and yield expansion of rock wedges are studied. Research shows that safety degree in sliding surface LS331 is lower than that in contact surface between the dam and the foundation，upstream dam heel of right bank begins to appear local yield when the overload safety coefficient is 1.5 with a consideration of many effects；the rock wedges cannot work normally when the overload safety coefficient is 3.1；the dam foundation can?t work normally when the overload safety coefficient is 3.3；and the rock masses under dam foundation is overall destroyed when the overload safety coefficient is 5.5.

Laboratory direct shear tests show that shear stress-displacement curve usually follows the pre-peak hardening and post-peak softening rule. When the asperities overriding effect is dominant，the curve shows stress hardening；and while damage and wear is accumulated to a certain extent，it will result in stress softening behavior. The hardening and softening effects together control the joint shear behavior. A new generalized hardening- softening constitutive model is put forward after detailed analysis of the existing model?s limitations. One function is used to describe the features of the pre- and post-shear curves and its advantages are as follows：(1) Don?t need discuss the characteristics of shear displacement curves for several segments and its fitting parameters separately. (2) Throughout the entire shear displacement range，this function has only one peak and at this point，its slope is zero. (3) Shear stress tend to residual strength when shear displacement is large enough which reflects the basic features of the joint material. The new model is suitable for analysis three types of shear displacement stress curves，which are shear stress hardening curve，hardening-softening curve and curve with an initial shear stress. Meanwhile，the limitations of the existing dilation models are that they cannot reflect negative dilation and the real point where the joint starts to dilate. So，a new normal-shear displacement coupling model is derived which takes two types of functions to express the different phenomena during direct shear test. At last，validity of the two proposed constitutive models is verified through applications to several existing laboratory test results. There is a high fitting accuracy between fitting results and experimental results.

In order to study the inherent relation between the mechanical behavior and the microstructure of the tailings used for building dams，we have developed an observation apparatus of micromechanics and deformation of tailings. It is composed of load device，compression chamber and appurtenances，local stress monitoring system，microscopic observation system. This apparatus has following advantages：(1) Tests performed on this apparatus can show the comprehensive influence of local stress，pore water and porous water pressure，drainage conditions in tailings dams on microstructure and particles motion. (2) The tests by this apparatus can be loaded under the modes of static load，static load and unload，dynamic load，dynamic cyclic load. (3) The compression chamber，which uses the structure of stainless steel cylinder with an inlaid glass fibre reinforced plastic cylinder，can offer the load pressure of 2.5 MPa. (4) When pore water is flowing in tailings，we can observer the movement of pore water and particles，microstructure and its deformation under load，also can monitor the pore water pressure by this apparatus. (5) The local stress can be real-time monitored through installing several pressure transducers inside tailings. (6) The self-made dynamic microscopic observation apparatus，which we have chosen，can be easily adjusted and track the movement of the point. The microscopic observation experiments of tailings are carried out by this apparatus under the loads of 0.3，0.6，0.9 MPa，and the result showes that：with the increasing of the load and the time，the amount and the size of macropores reduce，particles have been bound to clump by weak bound water which is transformed from strong bound water. With the increasing of the load，the displacement increases nonlinearly，and the increment of the displacement become smaller. With the effect of the load，the stress and the microstructure deformation show that：the lower of the specimen lags the upper of specimen，the local stress increases wavily；and the value of peak of local stress changes very heavily；the displacement has a stepped increment，and finally becomes a stable level.

Gypsum rock is commonly found as an interlayer in bedded salt deposits which are solution mined for the purpose of salt mining or oil and gas storage construction. To investigate the related mechanical properties of gypsum rock under the situation，series tests of uniaxial compression，tensile and shear strength are carried out in the laboratory with gypsum specimens soaked in brine of different temperatures and concentrations. It is demonstrated that the strength of gypsum rock is weakened to different extents with brine temperature and concentration increasing and soaking time lasting. The strength softening coefficient can be as low as 0.10 to 0.73 after being soaked in hot and concentrated brine for 60 d. The elastic modulus of the gypsum rock is also linearly decreased with the temperature and concentration of brine increasing. The elastic modulus of gypsum rock is 5.92 GPa after being soaked in half saturated brine of 40 ℃ for 60 days，however it suddenly decreases to 0.21 GPa when being soaked in saturated brine of 70℃ for the same time. Similarly，the tensile strength also decreases from 0.64—0.66 MPa soaked in brine of 40℃ to 0.27—0.47 MPa of 70 ℃. After being soaked in saturated brine of 70 ℃ for 60 d，a regressed equation for Mohr-Coulomb shear strength of the gypsum rock is obtained as  . Two similar strength equations are also regressed as  ，  when the soaked time is 30 and 80 d respectively. It demonstrates that both the cohesion and inner friction coefficient of gypsum rock decrease with soaking time lasting. A parameter of failure rigidity is defined to illustrate the difference of gypsum failure at different situations. According to the calculated results and the geometry of stress-strain curves of the gypsum rock under uniaxial compression，the failure style of gypsum rock changes from brittle to ductile damage obviously with increase of the temperature and the concentration of soaked brine. The study is significant not only for the investigation of hydromechanical property of gypsum rock，but also for guidance for solution mining or storage cavern construction in bedded salt deposits.  

Experimental study is made on microfracturing progress of microcrack of sandstone and its distribution characteristics after failure under shear loading condition by independent developmental coal or rock microscopic shear testing device. Simultaneously，temporal and spatial evolution law of microcrack of sandstone under the shear loading is also researched by image processing technology. The results show that damage of sandstone specimen in external appearance is unconspicuous in most part of the loading process，and microfracturing progress of sandstone is finished in a relatively short time. Deformation of sandstone is also small during the fracturing progress. The conspicuous microfracturing progress is in the damage stage after peak stress and in general the fracture is extended upward from the bottom of the specimen. Furthermore，in the process of rupture failure of sandstone，it is produced both intergranular fracture and transgranular fracture，however，the main microfracturing progress is produced in grain boundary and cement；this is mainly low consume energy in the failure mode. Because the fracturing progress of microcrack is influenced by permutation and combination mode and cementation degree of mineral particles in sandstone surface；the spreading direction of microcrack has irregularity，which has bias in some degree compared with predetermined shear plane.

To simulate the progressive failure process of the slope in water level fluctuation and rainfall conditions，a coupled fluid flow and stress computation model of dual media is established based on continuum-medium distinct element method. It contains solid calculation model，pore hydromechanical coupling model and fissure hydromechanical coupling model. Solid calculation model could reflect failure regularity of the geologic body，also could simulate the process from continuum to discontinuum. Pore hydromechanical coupling model could calculate the location of phreatic surface conveniently. Fissure hydromechanical coupling model could avoid convergence problem caused by isolated fissure. Considering the final states of the water level fluctuation and rainfall，the waterhead distribution caused by fissure seepage and water level fluctuation in reservoir are regarded as the variable boundary condition，thus implementing the coupling analysis for pore and fissure seepage flow field. Typical example computational results show that a coupled fluid flow and stress computation model of dual media based on continuum-medium distinct element method is very effective for the analysis of reservoir ancient landslide.

Inflow performance relationship(IPR) in single-phase(water) coalbed methane wells provides the basis for the reasonable operating practice and dynamic analysis. The mathematical models of IPRs for Darcy and non-Darcy flow in coalbed methane(CBM) wells are developed based on the fluid mechanism in porous medium. The IPR curves are obtained with the field examples in Ordos Basin. The results show that the small errors of less than 12% between the prediction and measured values are achieved due to the reservoir parameters，fluid physical property and non-Darcy skin factor. The IPR should be analyzed by the Darcy model with constant supply boundary pressures for the low flow velocity. However，the non-Darcy model should be involved while the Reynolds number is over 0.3 and water production is more than 30 m3/d. During the initial pumping production，the water flow rate and coal particle migration can be controlled due to the increase of pressure drop，which is beneficial to water flow. And an increased pressure drop from 0.44 MPa up to 3.68 MPa leads to the enhanced water production from 10 m3/d to 40 m3/d. The increase in the integrated flow conductivity of coalbed and deliverability occurs with the increment of permeability. And the increase of permeability from 0.9×10－3 ?m2 up to 6.15×10－3 ?m2 leads to an increment in water production from 3.5 m3/d to 15.9 m3/d. The decrease of skin factor makes the IPR curves move towards the right direction. And the reduction in skin factor from －3.10 to －4.85 yields the increase of water production from 34.8 m3/d up to 45.6 m3/d.

the study of protective effect of buffer blasting on the reservation slope in open-pit mine is decribed. Based on the data of blasting vibration in the open-pit mine，the data of blasting experimental vibration on having or not having buffer blasting hole are given by setting reasonable buffer blasting parameters. Using FEM program of LS-DYNA，the two different numerical models are made to study the bench blast；and comparative analysis of the simulation results with the results of field experiment makes a conclusion that the more near from is the explosion source，the better decreasing effect is；and half cast factor can be improved mostly 30% of the presplitting blast hole. On the basis of comparative analysis of the simulation results and the field experimental data，it is concluded that it will decrease the blasting vibration 51 % under the same condition with having the presplitting blast hole at mostly，so it will do strongly protective effect on the reservation boundary working slope.

Affected by Qinghai—Tibet Plateau tectonic structures，numerous accumulations slides which have the characteristics of multiple formation types，complex mechanism，sudden occurrence，difficult to predict the developing trend，huge damage，etc.，are distributed in Southwest China. Among of them，Jiaju landslide，which locates at the upper reach of Dadu River，is a typical ancient one with dramatically thick depth and localized resurrection tendency. A comprehensive monitoring system including GPS，InSAR and Inclinometer has been carried out to monitor both surface displacement and deep displacement. The result shows that Jiaju landslide nowadays is at an evolutionary stage with accelerating deformation in the surface and slow deformation in the deep body. And further analysis of the monitoring results indicates the deformation and failure modes are the combination of sliding and compression cracking in the surface and fracturing in the deep position. In order to testify the monitoring results，FLAC3D numerical simulation method is adopted and the stress field，distribution of displacement and plastic zone in the dynamic deformation process for Jiaju landslide are all simulated；and simulation results are consistent with monitoring results.

In order to study the influence of horizontal joint on the rock fragmentation when disc cutter penetrate rock，the wedge indentation penetration experiments of similar material are carried out under simplified actual conditions using improved experimental device. The digital image of the deformation and failure process of specimen surface are obtained in real-time by using charge coupled device(CCD) camera. Digital speckle correlation method is used to analyze the collected images and the displacement field of the specimen surface. The damage of specimen under concentrated load by wedge indenter is expressed by the variance of the displacement field. Acoustic emission testing system digital signal processing(DISP) is applied to get the localization of micro-fracture failure on specimen surface，and analyze the formation mechanism and the characteristics of acoustic emission(AE) concentrated in space when the specimen with horizontal joint.

The formation of compaction bands could greatly reduce the permeability of rocks，which has potential economic value. In order to research the characteristic of permeability change during the formation of compaction band，permeability change with confining pressure unloading and the relation between volumetric strain and permeability change，weathered high-porosity rocks are used to carry out triaxial compression tests and obtained the permeability during the processes. Discrete compaction bands，high-angle shear bands，and the hybrid modes of two of the three involving discrete compaction bands，diffuse compaction bands and high-angle compaction bands are observed；three patterns of permeability change have been also observed. The permeability reduces with the increase of axial strain，the permeability suddenly reduces when the first localization compaction band formes. The reduction of permeability is blow 2 orders of magnitude，and most is blow 1 order of magnitude. This is lower than other results of 2—3 orders of magnitude；but it is consistent with the result of no severe grain crushing. The volume of the samples dilates but the permeability reduces at the later loading stage. So，there may exist the phenomenon of permeability reduction with the porosity increase. There are different patterns of permeability change during the process of confining pressure unloading. The permeability of some samples consistently increases with the decrease of confining pressure，and the increase speed is also increase. Another pattern is that the permeability decreases first and then increases with the decrease of confining pressure.

In order to study the effect of water-saturated state on mechanical properties of rock in coal measure strata，Brazilian Split test，uniaxial and pseudo-triaxial compression experiments are carried out to investigate sandstone，sandy mudstone and mudstone specimens under natural and water-saturated state by rock mechanics test equipment RMT–150B. The results are as follows：the average rate of water absorption of sandstone，sandy mudstone and mudstone is between 0.241% and 0.482%；water absorption rate with respect to time can be fitted with logarithmic relationship. Different influences of the strength and deformational character among these three types of rocks are found after reaching water-saturated state，mudstone performs most obviously，then comes the sandy mudstone and the sandstone. The softening coefficient of tensile strength is roughly between 0.40 and 0.92；softening coefficient of uniaxial compression strength is between 0.58 and 0.94；reducing coefficient of elastic modulus is between 0.58 and 0.95；reducing coefficient of deformational modulus is between 0.68 and 0.94；and the reducing coefficient of Poisson ratio locates in the range of 1.08–1.11. The softening coefficient of peak strength measured by triaxial compression tests-K and the confining pressure-?3 are approximately positive correlated. It is indicated that the sensitivity of peak strength to the confining pressure in water-saturated state is greater than that in natural state. Water-saturated state can reduce the cohesion of these rock specimens；the percentage of reducing lies between 20.6 % and 67.0%. On the other hand，internal friction coefficient almost keeps in the same level；it is shown that the former coefficient is a structural parameter and the latter is a material parameter.

Based on the wavelet transform and Gamma correction，a new digital image processing technology (DIPT) is proposed. Then it is applied to the discrete element simulation of talus deposit；the numerical model can be established fast and correctly. As for the technology，the two-dimensional wavelet theory is used for the denoising of digital image，then the adaptive Gamma correction method is adopted to eliminate the impact of different lights and environments，and finally，the color space is conversed for the binary treatment. Based on the study of DIPT，a Wavelet-Gamma-Conversion(WGC) auto-modeling program is developed. It is able to realize the whole process：acquiring the information，analyzing and processing，establishing the micro-model files. A new modeling method is developed for the mechanical behavior simulation of talus deposit. As an example，some talus deposit data of Gushui hydropower station is used；and then the micromodel is established by the WGC from the digital photo on-site. The mechanical properties are studied by the numerical simulation of biaxial compression test. The results show that the gravels and soil mass compress with each other to form a corporate load-carrying body for sharing the external forces. The stress-strain curves show a strain-hardening stage evidently due to the impact of gravels. With the increasing of bond strength between soil particles，the initial elastic modulus and peak strength of talus deposit go up at a certain level. The law of the numerical simulation test is in agreement well with the results of laboratory test.

A new method for picking up coupled nodal forces in coupled micro-macro model is presented. By enforcing the compatibility of coupling boundary nodal forces obtained from discrete and continuum models，picking up coupled nodal forces is converted to an optimization problem solved by Lagrange multiplier method. Based on two-scale coupled approach，tunnel and its surrounding soil under periodic train loading are simulated. Particle flow code in 2 dimensions(PFC2D)，which is based on discrete element method，is used to simulate sands near the tunnel，while the domain containing particles away from the tunnel is simulated as continuum media by FLAC2D. The motion of the tunnel is governed by a self-edited dynamic finite element program which is added to PFC. Coupling is achieved by interchanging data between the two softwares during each time step. The continuity between the discrete and continuum domains is fulfilled by interchanging velocities and forces；and a free-vibration column simulation is applied to obtain particle assembly?s macroproperties. Through comparison between results from coupled model and continuum model，the effectiveness of the presented method is demonstrated. It is shown that，the coupled method can well depict the concerned zone around the tunnel on the micro-scale while efficiently reduce particle numbers，and is suitable for micro-scale dynamic analysis of concerned zone in a semi-infinite body.

Lots of intact sliding zone soil samples are collected from Huangtupo landslide，Badong town. CT scanning technique is used to get the grain distribution of the intact soil samples. 30 scanning samples are selected，and according to the statistics result，the average percentage of gravel(particle size more than 2mm) is about 30%；so the intact sliding zone soil should be treated as soil-rock mixture. Typical CT scanning images are rasterized；and then triaxial numerical tests on the rasterized soil samples are conducted. The mechanical parameters of granule part (particle size less than 2 mm) in intact soil are obtained by direct shear tests；while the mechanical parameters of granule part in intact soil depend on that of sliding bedrock. According to numerical calculation results，the deformation and failure mechanism of intact sliding zone soil is analyzed including distinguish between mechanical parameters of intact soil and that of only granule soil part. The results show that comparing with the shear strength parameters of granule part，the internal friction angle of intact sliding zone soil doesn?t increase obviously；meanwhile，the cohesion increases at least 80%. It?s because the percentage of gravel in soil-rock mixture is only about 30%，which still keeps the granule soil part to be framework of soil-rock mixture. During the shear deformation process，the motion velocity of gravel is lower than that of soil，combining with the activity of normal stress，it supports an effective resistance to granule soil，just as similar as the external friction angle between retaining wall and backfill soil. In the Mohr circle，this action can be reflected by the increasing of cohesion of soil-rock mixture. By analyzing the mechanical traces on the surface of a rock block，the evidence is found. This research method can provide a new method to obtain reliable shear strength parameters of intact sliding zone soil.

It is inevitable for the slurry shield to under-pass the embankment in construction of under-river tunnels in urban areas. For the safety of both the embankment structure and construction，resources of risks when slurry shield under-passing the embankment are analyzed in detail，and their causes，impacts and mitigation measures are also studied accordingly. The case history of risk control for slurry shield under-passing the embankment in Hangzhou Qingchun road cross-river tunnel in China confirmed the rationality and feasibility of the suggested risk control measures. Through optimization of slurry shield driving parameters，avoidance of adverse external conditions，in-time monitoring，and setting of detailed emergency countermeasures，some of the risks encountered during slurry shield under-passing the embankment can be reduced or mitigated so as to insure safety of the embankment and construction.

It is a difficult research topic of the rule about water flow in the unsaturated intact loess；this subject develops slowly by now，owing to the complex theory and the lagging of experimental method. This article addresses the problems of temporary saturated zone and transport progresses of water in unsaturated intact loess slope. The authors analyze the variation regularities of daily moisture content of soil within the depth of 2–3 m beneath the immersion test pit，discuss the formation of transient saturated zone and migration process，canvass formation mechanism of infiltration regions in unsaturated intact loess slope and migration rules of water in unsaturated intact loess slope. The results show that the process of infiltration in the unsaturated loess slope is the process of continuously enlargement of transient saturated zone；permeability zones and the value of wetting angle are not fixed，and both enlargement as infiltration capacity of water increasing. Permeability zone could be divided into four parts：the first and second parts are the stage of water lateral migration；the third part is the stage of vertical permeability；the forth part is the wetting front of temporary saturated zone；permeability zone in the unsaturated loess would be closed region of approximate oval forever.

Based on the bound theorems of limit analysis，admissible velocity field of horizontal strip anchor is constructed by using a combination of several rotational block sets. An application to upper bound analysis of vertically loaded strip anchors on horizontal ground surface is given first to illustrate the utility and effectiveness of the proposed method，and include detailed comparisons with results obtained from other approaches. Then the pull-out capacities of strip anchors in undrained clay with sloping ground surface are analyzed. Pull-out capacity and failure surface characteristics under different embedment ratios，undrained strength，inclined angles of slopes and weight of soil are studied. The results show that the superposition of gravity is not applicable to the case of sloping ground surface. The variation of slope angle has a significant impact on failure surface. The block set mechanism is based on a very simple concept which is integration and combination and can be a reference for the practical design.

Applying combined calculation of water and earth pressures for clay leads to a result which is more close to the field measurement value，however，obviously violates the principle of effective stress. Based on characteristics of the pore water in soil，it is assumed that the bound water absorbed by the clay particles in the soil offsets part of soil pore，and finally physical parameters such as void ratio，boundary water content，particle analysis，etc. are introduced to calculation of water and earth pressures on retaining structures to propose a coefficient   which can be calculated through physical parameters of soil and to provide the method of measuring the value of   through permeability tests. With the coefficient  ，the effective stress intensity index and total stress intensity index are integrated in one strength formula. A new calculation method to unify the separate calculation and combined calculation of water and earth pressures is proposed to carry out the transition between results of the two conventional calculation methods and provide a new idea for solving the jump problem between the two results. According to the theory analysis of this paper，the measured permeability coefficient-void ratio curve will have a translational move in a forward direction along e-axis. The more clay particles that soil contains will have the larger translation，which has been verified by experimental data of related literatures. Separate calculation of water and earth pressures is too conventional for sand soil containing clay particles while combined calculation of water and earth pressures for clay with high void ratio can?t guarantee the safety. Water and earth pressures on retaining structure are related not only to the soil categories，but also the void ratio.

The effect of soft substratum on the stability of soil-nailing walls is discussed through analysis of project cases. The deformation characteristics of soil-nailing walls in soft soil area are revealed. Some measures are proposed to control the deformation. Besides，field tests are carried out through pulling out soil nails in soft soil area with high speed and low speed respectively. The test results are compared and the characteristics of the resisting force when pulling out the nails from soft soil are analyzed. Based on the test results，a quick pullout capacity test method is proposed. Some suggestions are put forward for the design of the length and space of soil-nails in soft soil area；and some opinions are proposed about the current soil-nailing retaining structure design code.

Conventional improvement methods of soft ground are ineffective or unpractial for ultra-soft soil formed by newly hydraulic mud fill. To meet the requirements of large-area reclamation by pumping filling in Tianjin Binhai New Area，a new improvement technology of shallow ultra-soft soil was proposed in connection with its engineering characteristics. It was introduced including the purpose，technical program，process points and application. Relying on a project in Tianjin Binhai New Area，the improvement effect was evaluated and the reasons and problems were analyzed with monitoring test results. Engineering practice shows that the water content of shallow soil reduces greatly；and its physico-mechanical properties are improved significantly after treated by the technology. A hard crust with a certain bearing capacity forms，which fully meets the construction requirements of hydraulic fill sand cushion and prefabricated vertical drains. The technology was applied successfully which has characteristics of low cost，short construction period and simple process and it is worth popularizing.