On July 13，2003，a foundation rock landslide with total volume of about 2.04´107 m3 happened in Qianjiangping on the left bank of Qinggan River in Zigui County located in the Three Gorges Reservoir area. Intensive attention has been aroused for the geologic features and startup mechanism of the landslide because it located in the Three Gorges Reservoir area and happened in the time no more than 2 weeks after the storage of the Three Gorges Reservoir up to 135 m elevation. On the basis of field investigation on the general geological conditions and its mechanical parameters of the actual landslide，and with advantages of real time variable employment and large discontinuous deformation simulation in the method of discontinuous deformation analysis(DDA)，the startup criterion for a landslide using DDA numerical modeling has been studied；and the numerical simulation of the startup and whole failure process of the landslide has been carried out by use of DDA method. It is shown that the main reason of Qianjiangping landslide is the reduction of mechanical parameters of controlled sliding surfaces in the landslide body resulted from rainfall and rise of reservoir water level. The landslide belongs to thrust load caused landslide. Compared to the actual process characteristics of the Qiangjiangping landslide，the maximum landslide velocity，and the maximum slide distance are quite reasonable and acceptable. The total duration of the landslide obtained by DDA modelling is about 40 s. In addition，the methods adopted in this paper supply a new approach for stability study of landslide or other geotechnical engineering.

The rock around tunnel is usually loosed by blasting excavation behaviors. The nonlinear plastic properties in the loose area influence greatly the measurements of tunnel deformation. A new back analysis method is proposed based on the simulation of construction sequence step by step. The measured displacement is divided into elastic and plastic parts according to the different tunneling states. A back analysis method for the elastoplastic displacements of broken rock zone around tunnel is proposed based on the measured plastic deformations. An example shows that the proposed back analysis method is reliable and useful for tunnel engineering.

A non-contact digital close-range photogrammetric method is presented in order to overcome the difficulties in the deformation measurement of large-scale tunnel and underground structures. This method employs only non-metric digital camera and requires no control points. One can set camera station arbitrarily and the entire three-dimensional displacement of numerous monitoring points can be obtained simultaneously. Compared with those traditional methods to monitor displacement by convergence measurement devices or total station instruments，it has the advantages of saving time，providing large quantity of measurement information and operational safety. A test is conducted in an actual cavern to verify the accuracy of the photogrammetric measurement for assessing the applicability to deformation measurement in tunnels and underground spaces. A comparison of the photogrammetric measurements with the total station instrument results shows that the measurement accuracy for deformation is considerably good；and it is a promising technique for deformation measurement of structures. An outline of the test and reports how the technique is applied to practical underground projects are provided. Some experiences are also summarized.

In classical soil mechanics，dilatancy is often considered as a monodrome function of the stress ratio for triaxial tests，then plastic flow direction is decided by uniquely and independent of material¢s internal state. This obviously contracts the observed facts. For two different examples of a kind of sand，one in loose state and the other in dense state，the loose sand contracts while the dense sand dilates when they are subjected to the same shear stress. These two different responses are corresponding to a same ，however，the dilatancies are different，one being positive and the other being negative. If the dilatancy is supposed as a monodrome function of ，the dissimilar characters for cohesionless soil in various initial densities and consolidation pressures cannot be simulated by a unified model. On the other hand，Drucker Postulate cannot satisfy all the conditions for soils，and a new energy dissipation mechanics is needed as the base of constitutive relation. The first and second law of thermodynamics，as the universal rules in the nature，can be invoked to describe the energy dissipation. Starting with this point，the corresponding yield locus and flow rule may be deduced in a systematic manner in terms of the free energy function and dissipation potential function. Within the framework of critical state soil mechanics，a modified model that combines the theory which treats the dilatancy as a state-dependent quantity with constitutive models is presented based on the first and second law of thermodynamics. This model accounts for the dependence of dilatancy on the material internal state during the deformation history，and guarantees the consistence of the dilatancy function with the yield locus because of the thermodynamics basis involved. The simulative capability of model is shown by computing different features under various initial densities and confining pressures in sand triaxial undrained shear test，using the modified model with a unified set of model parameters and the hardening rule suggested.

The factor of safety of a slope based on limit equilibrium method is largely dependent upon the assumption regarding the distribution of normal stresses on the slip surface. Thus，investigation of the effect of this distribution on the factor of safety is of practical significance. A series of normal stress distributions are represented by a cubic spline function with five discrete points，and the associated factors of safety are computed according to the force and moment equilibrium conditions for the whole sliding body. Comparisons are made between the differences in values of factors of safety and the reasonableness of the internal forces is checked. Example studies show that the maximum differences in values of factors of safety with different normal stress distributions are within 19%，which is reduced to be less than 7% after checking the internal forces.

Based on unified strength theory，considering Lode parameter，unified strength parameters of materials are proposed，which change with Lode parameter and the intermediate principal stress coefficient b，and planar style strength criterion of unified strength theory which can consider the intermediate principal stress is obtained. Assuming distribution statistical probability of micro-units strength，statistical damage variable is defined；and the statistical damage constitutive equation is proposed under triaxial stress state based on the unified strength theory. The proposed constitutive equation is verified by triaxial experiment of soft rock，the comparison between experimental results and theoretical results is processed；and the results show that the proposed constitutive model can predicted the relationship between stress and strain of soft rock，especially the characteristic of strain softening. Furthermore，on the basis of the unified strength theory and the mobilized internal frictional angle of the unified strength parameter，effects of Lode parameter and the intermediate principal stress coefficient b on deviatoric stress-strain relationship are investigated theoretically；and results show that the deviatoric stress-strain curves rise to a certain value with increasing Lode parameter，and then decrease with Lode parameter；and the deviatoric stress-strain curves rise with increasing intermediate principal stress coefficient b.

A theory of dynamic FEM and a numerical method for the lining structure of tunnels are put forward. Based on in-situ measurement results of vibration loads for the train running on the Zhuting tunnel of Beijing—Guangzhou Line，the dynamic response characteristics for three types of tunnels with different cross-sections are investigated. And then，the distributing characteristics of the vertical displacements and internal forces are obtained for the lining structures of three types of tunnels. The research results have important denotation not only for the dynamic stability evaluation of tunnel structures for speeded railway but also for the tunnel design and construction of railway.

A constitutive model，which can almost describe the characteristics of rock mass truly，is obtained by perturbation method. The curve of the constitutive model is linked glossily by elastic，strain nonlinear hardening and nonlinear softening segments. The stress distribution laws in plastic hardening and softening zones of surrounding rock under hydrostatic pressure are achieved. Based on the analyses，equilibrium equation of surrounding rock，relationship between geostress and tunnel displacement and characteristic equation of surrounding rock are presented；and the expressions of geostress shared by elastic zone，hardening zone and softening zone of surrounding rocks are given. Calculation shows that the bearing capacity of the hardening zone of surrounding rock is more large than that of elastic zone. Especially，the curve of sq /po-r/a has no up-pinnacled stress concentration；and the result accords well with the experiment one of other scholar. It is pointed out that there are obvious limitations in Kastener formula which is based on ideal elastoplastic constitutive model；and the up-pinnacled stress concentration of sq -r curve does not correspond with the practical one.

Compression tests are conducted on intact loess obtained from Xi¢an and Lanzhou with different water contents. The quantitative comprehensive structural parameter is defined by using porosity ratio of intact and disturbed saturated loess under the same pressure. The effects of moistening water content w and pressure on the structural parameter are investigated. The mechanism of moistening deformation is analyzed using characteristics of the structural parameter change. The study indicates that：(1) the structural parameter decreases and coefficient of moistening collapsibility increases during moistening process under condition of the same pressure，but they scarcely change when moistening water content w is less than the initial moistening water content with structure destruction wf which locates at the turn point and decreases with the increase of pressure. (2) when w is less than wf，water sensitivity of loess is very weak，but it is very strong when w is large than wf. (3) moistening collapsibility is greater under high pressures，and it is weaker under low pressures. The effect of pressure on moistening collapsibility is more obvious at small initial water content than that at large one. (4) moistening deformation decreases with the increase of initial water content w0 under the same w，but its change has no effect on the deformation when w0 is less than wf. (5) the linear relations between and ( ) is almost the same for Xi¢an loess and Lanzhou loess under the condition of different pressures and initial water contents. Namely，structure nearly has identical influence on the growth of moistening deformation under different conditions.

The two major issues in front of the worldwide mining industry are work safety and protection of ground environment when carrying on underground mining activities. Cut-and-fill mining method is increasingly applied in China owing to its advantages of controlling ground pressure and protecting the ground environment effectively. However，few works and reports are known on the topics of large-scale rock mass movement and ground fissures resulting from the mining with backfill. An introduction to the phenomena of the ground surface deformation and ground fissures due to underground mining is given in Jinchuan Nickel Mine which is the largest underground mine with cut-and-fill mining in China. In 1999，many ground fissures and breakage on the ground surface appeared in Jinchuan No.2 Mine. Following an introduction to the distribution of the ground fissures and the correlation of the fissures with the location of underground ore body is presented. The emphases are put on the field investigation and monitoring for the fissures. A new type of three-dimensional fissure instrument IGG–1 is invented to measure the change of the fissures with the mining. The results of the measurement show that the three-dimensional displacement characteristics are distinct for the ground fissures. The mechanism and the influential factors are revealed from the field exploration and monitoring. It is shown that the stress redistribution in surrounding rocks resulting from the mining，low stiffness of the filling body，the existence of the void space underground and the influence of on-going mining activities are the main reasons for the occurrence of ground fissures. It is thus concluded that in mine design with cut-and-fill mining，the ground surface deformation and fracture must be taken into consideration.

The in-situ stress of rock mass is determined by Kaiser effect of rock under uniaxial compression. This method is applied widely in rock mass engineering. Based on the recent in-situ stress field by Kaiser effect，direction of modern in-situ stress field，direction of in-situ stress in the location of samples and in-situ stress in the three directions are presented by Kaiser effect of rock under uniaxial compression and micro-fault research methodology in Qinling area along Xi¢an－Nanjing Railway. Modern in-situ stress field is in the direction of northeast，and the in-situ stress gets up 15 MPa. The results by Kaiser effect are consistent with those of field test.

To study stress corrosion and chemical corrosion coupling effect，the corrosion environment and the corrosion situation of anchors，where the anchors are buried in the Jiaodong Coal Mine in Jiaozuo City，Henan Province，are discussed. The spot corrosion，pitting corrosion，weight loss，corruption speed and strength loss rate，etc. are study. The results show that the strength loss rate of naked-scaled anchor is about 14.0%，the diameter loss about 10.0%，and the sectional area loss about 19.0% under the medium corrosion condition. Especially，the weight loss rate is extremely unevenly distributed：the maximum rate is about 24.4 times against the minimum one. After 17 years，the limit tension load is 18.4%–22.2% lower than that of the new one. The data of durability and service life of the 17-year anchor are acquired，which can provide references to the investigation of the protective countermeasure against the corrosion of anchor.

The creep property of rock salt varies with the mineral gradients and loading level. Through creep experiments on rock salt and glauberite rock salt with different stresses and sample sizes for more than 100 days，the following results，which are elaborately described in the paper，are obtained：(1) under the same stress 7.0 MPa，the creep ratios of glauberite rock salt and rock salt are 8.72×10－6 and 2.38×10－4 d－1 respectively，and the former is only 3.67% of the latter；(2) under different stresses，the creep properties of two kinds of rock salt are different from each other. The rock salt loaded by 7.0 MPa shows a higher creep ratio，which is 2.38×10－4 d－1，while the creep ratio of the sample loaded by 4.0 MPa is 3.77×10－5 d－1，which is only 15.87% of the former；(3) under different stresses，i. e. 7.0 and 12.0 MPa，the creep ratio of glauberite rock salt is 8.72×10－6 and 1.12× 10－5 d－1 respectively. The higher the load is，the greater the creep ratio is. Finally，a creep constitutive equation of rock salt is established based on the theoretical analysis；and it fits with the obtained creep data very well. The results obtained and constitutive equation can provide some references for stability analysis of oil and gas storage constructed in bedded salt deposits.

Frozen soil is a kind of multi-phrase compound material. There are many defects and micro-cracks in frozen soil. Supposing the defects as the initial crack，using the theory and testing method of fracture mechanics，the nonlinear fracture process and character of frozen soil are investigated. The result shows that the nonlinear fracture process of frozen soil is composed of elastic period，micro-crack damage zone(MDZ) forming period and softening period. MDZ forming period is the main feature of nonlinear failure of frozen soil. The micro-crack is regarded as the virtual crack，considering the cement ice in frozen sold，the cementation force crack model of nonlinear fracture failure is presented. The material in MDZ is partially damaged but still able to carry cementation stress ，which is nonlinearly distributed over the length of MDZ. Then the method to calculate the length of MDZ is proposed. This model can offer some references for theory analysis and numerical calculation. Finally，the test method of nonlinear fracture toughness index involved in cementation force crack model and the corresponding results are given.

The rock mass of open mine slope is the 3D damage mass，which contains a large amount of joints distributing randomly in space. Because both its strength and joints distribution are random，the damage of rock mass is a kind of probability damage. According to the definition of damage tensor of jointed rock mass and simulation of 3D joint network，the analysis approach and program of the damage tensor and the probability distribution rule of jointed rock mass are put forward. Based on the Rosenblueth principle，the theories of effective stress in damage mechanics and fracture mechanics，FLAC3D numerical simulation and 3D joint network simulation，etc.，the coupling analysis technique of the probability damage evolution in 3D jointed rock mass has been established. It organically combines the damage theory，fracture analysis of jointed rock mass and numerical simulation of slope excavation，and provides a practical approach for the probability damage evolution rule of jointed rock mass. The formation of slope is a long-term process during mining. With the development of mining engineering，damage of jointed rock mass is progressively accumulated. The results have been proved during the excavation of the south slope of Yanqianshan Open Iron Mine. The assessment and working process of the probability damage and the evolution are systematically studied with the excavation of the rock slope. The spatial distribution and evolution of the damage rules of the rock slope are quantitatively shown. 3D random damage fields of the rock mass in different excavation stages are established by applying Rosenblueth principle and numerical simulation of the damage evolution. The damage tensor，the mean and the variation of damage degree are calculated. The dynamic laws of stability and reliability of open pit mine will be well studied.

The realistic characterization of rock heterogeneity has been a long-standing problem of great practical interest. The heterogeneity of the fractured rock masses can be described by statistical random sampling in most numerical simulations. In this study，a digital image based(DIB) numerical method is proposed for the two-dimensional transient seepage analysis of the fractured rock masses by actually taking the spatial distribution of main fractures，minor fractures and intact rock into account. The digital image processing technique is developed to identify and classify the main structures(i.e. fractures，intact rocks) in the fractured rock masses and their intrinsic permeabilities are specified to these main structures. Then the characterized permeabilities of these structures are directly imported into newly developed three-dimensional simulator SCMR，a FEMLAB-based simulator of coupled multiphysics in rocks，to evaluate the effect of heterogeneity on the transient fluid flow in the fractured rock masses. The digital image based numerical results of transient fluid flow show that the digital image-based technique is capable to characterize the heterogeneity and the fracture structures of fractured rock masses. The digital image based technique is more advantageous than the statistical method in characterizing the rock heterogeneity and provides a new approach to obtain the realistic results.

The experiments used to detect the characteristics of soil under the condition of principal stress rotation are analyzed systematically. Some conclusions have been drawn as follows. Under the condition of undrained principal stress rotation the pore pressure is generated and accumulated，which is especially obvious in the cyclic rotation；and the pore pressure is usually larger than that in the dynamic triaxial or torsion shear test at the same level of the shear stress. Besides，the mode of the pore pressure accumulation has a certain functional relationship with some kinds of strains，and is influenced by the inherent anisotropy of soil，but this influence is also inhibited at the low level of the shear stress. During cyclic rotation the pore pressure is also influenced by the rotation amplitude，frequency and cycle times. The cyclic stress rotation does not obviously change the effective internal friction angle of soil，and quite a few tests show that whether the soil has experienced principal stress rotation or not，the normalized shear strength criterion is same. But some results convince that the axis of inherent anisotropy can rotate with the rotation of the principal stress under drained condition，which leads to the different shear strengths before and after rotation. During the principal stress rotation the direction of the principal strain increment is between those of the principal stress and the principal stress increment. The degree to which stress-strain relationship influenced by the principal stress rotation as stress history is mainly dependent on the strain level having accumulated during principal stress rotation. The suggestions to bring pore pressure，strength，and stress-strain relationship into consideration on the further experimental study are also put forward. The higher shear stress level is，the higher frequency tests should be taken and the influences of specified stress factors on the properties of the soil under principal stress rotation need to be further investigated.

A calculation method of reliability for slope stability，whose state function is implicit function，was researched. The Janbu method as an example for the calculation procedure and process of stability coefficient of slope，in which mechanical model sliding surface is deemed as a non-circle，was introduced firstly. It was put out that the calculation for the stability coefficient of the mechanical model of implicit function was regarded as a test method. The implicit equation of calculation stability coefficient was taken place by an approximate equation that was fit through test results by response surface method idea. The limit state equation was established by using the approximate equation；and checking point and reliability indices were calculated. The approximate equation of calculation stability coefficient was combined with implicit function and the checking point to decide a new basic point and the sample points. New approximate equation and reliability indices were performed circularly until the reliability index was converged. The approximate calculation method of stability reliability for slope whose state function was implicit function was established. The accuracy of the approximate method was validated through comparison between reliability indices calculated by different methods. A stability reliability of open pit slope was analyzed by the approximate method at last.

Hydraulic fracturing has originated as a stimulation technique of oil reservoir，and has been developed as a rock stress measurement technique. Recently，it has also been developed to create artificial heat exchange surfaces for hot dry rock power generation system. To study the mechanism of crack extension by hyduaulic fracturing，the mass hyduaulic fracturing experiments are carried out in granodiorite at Fangshan District，Beijing，China. A FR borehole of 301 m deep in a fresh and intact rock is used for the experiments. During the fracturing process，electrical potential changes around the injection well are measured on the surface. Measurement points，total 49 points，distribute around the injection well on the grid with interval of 25 m in an area of 200 m×200 m. Hyduaulic fracturing experiments are carried out by selecting 3 spots without natural joints from the section of 110 m to 140 m in the depth of the FR borehole. These spontaneous potential(SP) anomalies show elliptical distribution in the map view. The values of the anomalies increase with the water flow. Most of the measurement results show that the positive elliptical anomalies have two long axes or one long axis with distortion to different directions. These directions coincide with the orientations of fracture and joint. In these cases，water is considered to flow into both the fracture and joint. The directions of crack extension obtained from the SP measurement agree with those evaluated one from the hydraulic fracturing stress measurement.

Emphasizing the importance of research on seismic response of shield tunnel and depicting its extinct features during earthquake，different traditional antiseismic analysis methods for shield tunnel are discussed with the merits and demerits pointed out by comparison. Then，aiming at a newly-built shield tunnel in Shanghai，a three-dimensional numerical simulation method for large-scale seismic response of shield tunnel is proposed with the character of fully emulating to the reality. Firstly，some basic and crucial theories and methods are introduced，including explicit finite element algorithm，time step control，hourglass control and dynamic relaxation. The three-dimensional analytical object is constructed from geometrical model to finite element model，which consists of surrounding soil，shield tunnel，connecting passages and many other objects with the total number of nodes and elements 4 million respectively. This model takes nonlinear behaviors of soil and contact interface between soil and tunnel into account；and the contact interfaces between lining segments are also considered. Final calculation is successfully completed on a high-performance computer. According to the calculation results，the whole tendency of shield tunnel reflecting heave and settlement are achieved，which reveals the interaction and distortion of the foundation soil-shield tunnel system under seismic loading. Besides，both the stress in lining segments and axial force in connecting bolts are investigated and analyzed respectively；and typical curves of force or stress variation with time are selected and illustrated in detail. Also，the stress distributions on the connecting passages and lining segments are shown；and corresponding weak zones are indicated consequently. In a word，it provides a practical method and meaningful data for the further research on aseismic design and research of shield tunnel.

According to the failure criterion of cumulating damage and one-dimensional spalling model，the condition of collapse induced by conventional explosion has been analyzed. According to correlative standards，the practical calculation method is achieved aiming at the steel fiber shotcrete support used in tunnel. The comparison between the calculated result and the numerical one shows that the calculation method is valid. In order to illuminate the resistance performance of steel fiber shotcrete induced by the conventional explosion quantitatively，the velocities of rockfalls from the top of tunnel supported by steel fiber shotcrete are compared with that of the tunnel supported by other kinds of support and that of the tunnel without support. The practical calculation methods offered can provide some references for design of steel fiber shotcrete support in tunnel.

A new method，particle swarm optimization(PSO) algorithm，is adopted to locate the non-circular critical slip surfaces of slopes. These slip surfaces are verified and refined frequently by PSO algorithm and tend gradually to the critical slip surface，and simultaneously their safety factors decrease towards the global minimum safety factors. The critical slip surface and its corresponding global minimum safety factor can be obtained within limited iterations. PSO algorithm can achieve a good balance between a global search and a local refinement；and it can solve the problem of falling into local minima，which happens in most of the regular optimization methods. At the same time，it shows great efficiency. Furthermore，PSO algorithm can be easily incorporated with the traditional limit equilibrium methods as well as the finite element method for slope stability analysis. A numerical example is analyzed to show the effectiveness and efficiency of the proposed method.

The stability characteristics of main seam roof in Yanzhou coalfield are analyzed. And the different influencing factors are generalized as the sedimentary characteristics，tectonic characteristics，mechanical property and some others. From sediment analysis，the main seam roof is divided into hardness-upward，softness-upward or their compound. From tectonic characteristics，the main seam roof is divided into super structure-development，structure-development，middle structure-development，and nondevelopment. From rock strength，the main seam roof is divided into extra-high intensity，high intensity，middle intensity，and low intensity. All factors are comprehensively analyzed，and based on analytical hierarchy process(AHP) and fuzzy mathematics method，the stability characteristics of main seam roof are evaluated in Yanzhou coalfield. The stability roof are divided into four grades：super stability，stability，middle stability and instability. The zone of super stability is thick coarse sandstones，with few structures and extreme high strength. The zone of stability is medium-bedded fine sand and silt with a few structures and intermittent，and high strength. The zone of middle stability are silt and mudstone with many structures of partly cutting through and medium strength. The zone of instability are mudstone and seam with large quantity and continuous structures and low strength.

Theoretical analysis shows that the height-to-diameter ratio and Poisson¢s ratio are two factors influencing the stress distribution within the flattened Brazilian specimen for the test to determine the tensile strength of rock material. Through 80 3D finite element computations，the stress distributions within the specimen for various height-to-diameter ratios and Poisson¢s ratios are obtained；and it is found that a breakage cannot initiate at the center of the ending surface during the test. Breakages initiating on the compressive diameter of the ending surface of specimen are defined as valid breakages. It is found that the ratio of tensile strength to compressive strength has notable influence on Mohr maximum equivalent stress within the specimen when the test is valid. The maximum equivalent stress based on Mohr theory occurs away from the center of the ending surface of specimen for an increasing ratio of tensile to compressive strength. And there exists a perfect linear correlation between Mohr maximum equivalent stress and the ratio of tensile to compressive strength. Based on 3D finite element computational results，a method and a formula for determining the tensile strength of the flattened Brazilian specimen are presented. In this method，Poisson¢s ratio，the compressive strength and a suitable strength theory are needed to calculate the tensile strength of rock material.

Applying stochastic theory to establish a 3D probability distribution model of discontinuities network is an important research subject of utilizing the computer programming technique in the field of rock mechanics. This technique obtains the original data of discontinuities from the in-situ investigation by sampling window method and creates a probability statistics distribution model of discontinuities geometric parameter；then，Monte Carlo method is adopted to build up a 3D discontinuities network model；finally，3D discontinuities network model is obtained with the help of computer. Based on the 3D discontinuities network model，the persistence is determined and the 3D shear strength indexes are provided by searching for the critical path of combined failure of the discontinuities and rock bridge. During the process of search，genetic algorithm which has obvious biological background is applied.

The fluid flow of an actual infiltration experiment performed in fractured rocks is simulated with channel flow model. When building the flow model，a network of disc-shaped fractures is constructed with inverse method firstly. Then，after the removal of unconnected fractures(isolated fracture or fracture clusters not linked to the infinite cluster)，the fracture network is simplified to a network consisting of channels in three-dimensional space. When constructing the channel network，for each disc-shaped fracture in the network，nodes are designed at the centers of its intersections with other fractures and the center of the fracture-disc；and each node at intersection-centers is connected to the node at disc center by a channel. The diameters of the channels are modified with observed discharge data. This is a process to modify guessed input channel diameters over likely ranges of values until a satisfactory match between the simulated and observed discharges for the infiltration experiment is obtained. It is impractical to modify the diameter of each individual channel. Consequently，it is assumed that，within a given fracture，the diameters of channels follow the lognormal distribution，so，only the mean and standard deviation of the channel diameters for each fracture set are corrected. To validate the stability of the model，20 fracture networks are generated and the flow in them are investigated. The difference between the measured and the average discharges of the 20 realizations is about 6%. That is，if the discharge of the experiment is predicted with 20 realizations of the stochastic model，the error of the prediction is about 6%.

Aiming at the defects and hidden troubles in reinforcement of layered slope by prestressed bolts，the mechanical mechanism is deduced theoretically and test is conducted and analyzed contrastively；and a conclusion that the change of designed inclination of anchors will bring a contrary influence on shear strength and withdrawal resistance of anchors is drawn，which makes design difficult. Therefore，a viewpoint that multiplex reinforced method of pressure grouting and anchors could solve the problems is brought forward. A bolted and grouted jointed model is established and analyzed；and a conclusion that pressure grouting will strengthen the shear strength and stiffness of bolted layered slope is drawn，it provides theoretical references for the multiplex reinforced method. Finally，the method is applied and validated by an actual engineering；and some key technological problems about the method are illuminated.

To investigate the process of cover splitting due to corrosion in the anchorage zone of bolts，the dummy radial displacements loaded on the hole in wall of bolts are used to simulate the expansion of corrosion products overlaying above bolts. The dummy displacements can be determined according to the quantity of iron corroded when uniform or nonuniform corrosion occurs to bolts. Then the splitting of the mortar cover due to the corrosion in the anchorage zone of bolts is numerically simulated by use of element Solid65 with the function of cracking based on the smeared fixed crack model in the finite element software ANSYS8.0. By use of an example，it is proved that when the corrosion quantity are equal，the cracks in the mortar cover and the destructive effects are obviously different around bolts uniformly and nonuniformly corroded，so the assumption of uniform corrosion should be adopted with caution in the prediction of time-to-corrosion cracking.

Based on the elastic plate theory，taking the influence of shear deformation into consideration，tunnel is regarded as the cylindrical shell on elastic foundation. By applying the theory of elastic cylindrical shell and simplified circular function，the overall stiffness of segment tunnel is separated as circumferential and radial shear stiffness and their effects on the deformation and internal forces are analyzed. The results show that it can improve the tunnel longitudinal structure behavior and reduce the bending moment of tunnel cross section by raising the stiffness of circumferential shear stiffness. It is suggested that a flexible ring with an appropriate stiffness should be applied in cross section design and a rigid design with certain flexibility in longitudinal section in soft ground. The conclusions are an important supplement for the theory of tunnel longitudinal shear transfer，which benefits to the optimization of the tunnel design.

By conducting field loading tests on single pile and composite foundations with single pile，four piles and nine piles with different lengths and area replacement ratios about compacted soil-cement pile composite foundation in unsaturated clay and silt，the failure pattern and the effect of pile length and area replacement ratio on bearing capacity of composite foundation are studied. By comparing the result of field loading test in different flat plates with sand cushion，the existing questions in evaluating the bearing capacity of the composite foundation are analyzed according to the results of the field loading tests on the composite foundation with compacted cement-soil single pile.

Wuqiaoling tunnel，the longest single-track railway tunnel in China，is the key project of Lanzhou—Urumchi Railway. It goes through four regional faults，and its geological and geostress conditions are complicated. According to the characteristics of soft rock and large deformation under the complicated stress condition，the comprehensive monitoring is executed during the construction in F4 section. Based on the measured results of the vault settlement，the horizontal convergency，the axial force of rock bolt，the surrounding rock pressure，the steel liner plate stress，the concrete stress of preliminary support，the stress and pressure of the secondary lining，the synthetical factors of the relation between measurement and construction procedure，the relation between surrounding rock pressure and displacement，the forecast of measurement，the developmental rule of multi-measurement items，the longitudinal distribution rule of displacement，the coefficient of lateral pressure，the shared ratio of secondary lining，the time of secondary lining construction，etc. are analysed. And the information is fed back to the construction in time. The structure stability is analysed and the corresponding measures are adopted，which can provide references for data simulation and theoretical analysis. The practice proves that the effect is reliable，the surrounding rock is steady and the structure is in good condition，which can provide a reliable technology reference for the perforation of the section.