The researches on seepage characteristic of rock joints are reviewed and analyzed. The results show that the experimental study plays a very important role in researching on hydro-mechanical characteristic of rock joints. Many researchers bring forward the experiential computation formulations according to the experimental researches，but there are not consistent understandings about them. The available research directions are put forward for the future research on hydro-mechanical characteristics of fractured rock masses.

There is no foolproof method by which the magnitudes and orientations of three-dimensional in-situ stresses can be reliably measured at great depths，although various field and laboratory measurement techniques have been proposed. In the case of scientific deep-drilling wells，therefore，it is desirable to combine borehole methods with core-based methods to obtain a complete three-dimensional in-situ stress. Here，the principles，testing techniques，and procedures for a new and effective core-based stress measurement method called anelastic strain recovery (ASR) technique are described；and then its application to a scientific deep-drilling project is shown. The measurement results reveal that the method is suitable for determining the orientations of the principal stresses and for estimating their magnitudes in deep drilling wells where other methods such as the over-coring technique and hydraulic fracturing tests are difficult or impossible to be conducted，or are needed complementary data to enhance the reliability of the stress measurements.

The practical techniques for risk analysis of earthquake-induced landslide are presented and discussed. The procedure of frequency analysis and consequence analysis for earthquake-induced landslide is proposed. A new concept of “critical line” proposed for the first time can make Monte Carlo simulation easier and more effective. The key problem in consequence analysis is how to estimate the travel distance，velocity and volume distribution of landslide，which can be solved by using the discontinuous deformation analysis(DDA) simulation. The results from a practical DDA simulation show the agreement with those observed from the past landslides. Therefore，the proposed way for risk analysis of earthquake-induced landslide will be put into practical use.

It is recognized that the intermediate principal stress plays an important role in strength and stress- dilatancy relation of soft sedimentary rock. However，few plane strain/true triaxial experiments on soft rock have been referenced in literature due to the relatively high strength of geomaterials. By using new apparatuses，triaxial and plane strain tests of sedimentary soft rock have been conducted. An innovative plane strain test system is introduced firstly，which can obtain real isotropic consolidation before shear and measurement of inner pore water pressure within/near shear band. Then，testing procedures including issues related to specimen preparation，are introduced. Finally，the strength characteristics，stress-dilatancy relation and creep behavior are analyzed. The following conclusions have been drawn. The strength of the soft rock increases under plane strain conditions，while the dilatancy decreases. The plastic potential function based on concept of tij is suitable for soft rock. Creep failure occurs only when the creep load reaches a threshold value；and the failure time is related to magnitude of creep load.

The groundwater inflow into a tunnel affects not only the construction schedule，cost，stability and safety，but also the groundwater level. Because of the increasing public concern regarding the impact of tunneling on surrounding environments，the control of groundwater has become an essential part of the planning，design and construction of a tunneling project. The impact on groundwater table due to groundwater inflow into Shinkansen (high speed trains) Chikushi Tunnel in Japan is analyzed by coupling geographic information systems(GIS) and FLAC3D. Firstly，the area around Shinkansen Chikushi Tunnel is drawn into watersheds using the hydrologic- analysis of ArcGIS；and tank model，which is a method for hydrologic balance analysis of precipitation，evaporation，water flow and infiltration，is used for calculating the rainfall infiltration. All the data，such as the geological data，three-dimensional terrain and rainfall，are processed using GIS. Then，a three-dimensional groundwater flow numerical model is used to predict the groundwater inflow into tunnel and the drop of groundwater level around the tunnel. Based on the 3D numerical model，considering the rainfall infiltration and the tunnel excavation sequences，a time-spatial simulation of the groundwater inflow and its influence on the groundwater level of Shinkansen Chikushi Tunnel are presented.

Distinct element method(DEM) provides a powerful analytical tool for modeling rockfall behaviors，i.e. trajectories，velocities and energies of falling rocks. Better DEM prediction of the motion of the falling rock requires realistic input parameter values used for the analysis. A methodology is developed in which the DEM parameters are determined from back analysis of a rockfall trajectory observed in field rockfall experiments or traced by site investigation of natural rockfall events. A number of techniques and strategies are proposed to ensure the efficiency and robustness of the solution procedure. The method is also extended into non-homogeneous slope cases，by applying repeatedly the presented procedure to each of the homogeneous segments along a given rockfall trajectory. Laboratory rockfall experiments on small model slopes are carried out to verify the proposed method. Case studies on well-documented rockfall records are also presented to show good performance of the method for both homogeneous and non-homogeneous slopes.

The coupled shear-flow behavior of rock joints is an important issue in rock mechanics. A number of coupled shear-flow tests were carried out under different normal loading conditions. By means of visualization system，flow images during shear process were taken and processed. Using the finite element method，with a special algorithm by treating the contact areas as zero-aperture elements，numerical simulations of fluid flow in joints were conducted. Numerical simulations providea good agreement with the flow rate obtained from tests，revealing that the flow paths and aperture distributions in a joint change remarkably with shear displacements，loading conditions and joint surface roughness.

Microcrack development patterns in Westerly granite specimens stressed immediately before their ultimate failure by uniaxial compressive loading are observed using the fluorescent method proposed by Nishiyama and Kusuda(1994). Applying this method，the microscopic crack growth patterns，such as cleavage cracks within feldspar grains and intracrystalline cracks in quartz grains，and the wide-area distributions of these cracks are simultaneously confirmed with accuracy and ease. As a result of the observations，the elongated contiguous cracks estimated to have a direct impact on the final failure of granite are identified；and these cracks are roughly classified into three types. It is inferred that these three types of cracks do not develop at the same time；and each type has a different mechanism of generation. The mechanism of crack development under uniaxial compression is suggested to occur as follows. Firstly，many microcracks running parallel to the loading direction are induced by loading. Next，long cracks are induced by the elongation and coalescence of these microcracks located near the sides of the specimen. Then，the sides move outward due to further loading，generating the fault plane. The cracks within the relatively less damaged remaining parts are linked and propagated；and finally，these cracks induce the failure of specimen.

Landslides and debris flows，the main types of movements when slope failures occur，are sources of severe geohazards in mountainous regions throughout the world. Area-scale landslide and debris flow hazard prediction and assessment are hot topics in the research of geohazards. The study of the mechanism and properties of historical landslide is a valuable reference for prediction and assessment of the future landslide hazard in adjacent or geotechnically similar area and is also useful for hazards mitigation. Most debris flows originally occur in the form of rainfall-induced landslides before they move into a valley channel. Based on the coupling of geographic information system(GIS) and numerical model，a two-step method is adopted to predict and assess the disasters of landslide and debris flow in Atsumari area，Minamata City，Kumamoto Prefecture，Japan. Firstly，the potential new landslides are predicted. Then，it is supposed that landslide will transform into debris flow when meeting heavy rainfall；using GIS-based numerical simulation model of debris flow，the inundated area across three-dimensional terrain is simulated；and the potentially affected homes，streams and road sections are predicted.

To visualize in detail the manner of deformation in rocks under various confining and pore water pressures，a micro X-ray CT system is used to obtain three-dimensional images with a high resolution of 5 mm. A new pressure vessel is developed to simultaneously supply both confining pressure and pore water pressure to rock specimens. Berea sandstone and Noto diatomaceous mudstone specimens with diameter of 10 mm and length of 20 mm are deformed hydrostatically. The diameters at every 15° are measured under various conditions of confining and pore water pressures. The average diameter decreases monotonically with increasing effective confining pressure，which is defined as the difference between confining pressure and pore water pressure. Sensitive orientation around the specimen diameter during pressurization is recognized，deformation anisotropy during pressurization then emerges and the anisotropic ratios reach a maximum value of 8% in the case of Noto diatomaceous mudstone. The method of micro X-ray CT is applicable for deformation measurements of small and irregular rock specimens under various confining and pore water pressures.

Uniaxial tension tests were conducted on specimens with three axial orientations taken from the same block sample of Inada granite for investigating anisotropy of strength and deformation. The experimental results reveal that the tensile strength and deformation properties of the Inada granite vary with the direction of tensile load. The strength and Young¢s modulus in the R-direction，perpendicular to the rift plane，are significantly less than those in other directions. In addition，the degree of anisotropy of tensile strength is largest compared with that of other physical properties. Moreover，a new type of specimen assembly is designed so that microscopic observations of fracture at different stages of the tensile failure process can be performed. Specimens before completely broken are successfully obtained，making such microscopic observation possible. The observed tensile fracture in a specimen examined at a stage beyond ultimate strength but before completely broken shows that the tensile fracture path is mostly within mineral grains in the granite.

The stress and seepage properties are mainly decided by the geometry such as surface roughness and aperture of rock joints；meanwhile，the different boundary conditions such as initial normal stress and normal stiffness also affect the stress and seepage properties. By using GIS technique，a new geometrical model is developed to describe the surface roughness and the aperture of a rock joint quantitatively. Numerical programs for simulating shear process are coded based on mechanical and hydraulic models of a rock joint；and then，the stress and seepage properties during the shearing processes are simulated and predicted by using GIS technique. The main results of this research show that during shear process，the normal stress，aperture of fracture and hydraulic conductivity increase gradually and reach to stable values at last under different boundary conditions as the shear displacement increases. The hydraulic conductivity increases with two orders. However，the shear stress leaps to a peak one at the first step and decreases quickly at the second step. And then，the shear stress under constant normal stress reaches a stable value soon，while the shear stress under constant normal stiffness increases slowly.

Transient pulse method is a theoretically well-established and widely used method at home and abroad. The limitation of the method in measuring range due to its fixed apparatus storage is discussed theoretically. Storage-variable transient pulse method for permeability has been proposed. The principle，test device and procedures of the storage-variable transient pulse method have been introduced；and the repeatability is analyzed based on the repeated permeability measurements at different apparatus storages. The results show that the measured values have a good repeatability(less than 5%) and well agree with that measured by constant flow method.

Risk management theory was applied to the restoration plan of a failure slope induced by the Fukuoka earthquake in 2005. The potential slope failure is simulated using the discontinuous deformation analysis(DDA)；and the risk of the slope disaster is evaluated for the potential failure slope of the three pointed-out cases based on the DDA results. Countermeasures for an appropriate failure scale in the restoration plan are proposed based on the risk analysis and risk pair convenience analysis.

A new geographical information system(GIS)-based landslide risk prediction method using Hayashi¢s quantification theory is proposed and applied to a landslide prone area in Minamata City of Kumamoto Prefecture. In the past，Hayashi¢s quantification theory was used in slope failure hazard mapping；however，the preparation of larger spatial data is very hard；the work efficiency is low；and the reliability of the results is doubtful sometimes. A preparation method of a series of GIS-based spatial data is proposed for quantification theory analysis；and the results of the analytical results can be input into GIS to make hazard map directly. The application of the proposed method in Minamata area shows that the created hazard map agrees well with the real slope failure condition.

Tank model is a helpful tool for rainfall-groundwater-runoff analysis since it can represent a nonlinear transport behavior and get solutions very quickly. It is known that the successful application of one conceptual model mostly depends on how well its parameters can be calibrated. Recently，in many literatures，it is indicated that by use of existing calibration methods，the calibration process with many parameters(such as multi-tank model proposed in this paper has parameters over 20) is typically difficult，sometimes even impossible to obtain unique optimal parameters. A new random optimization approach called dynamically dimensioned search(DDS) algorithm is introduced and improved for parameters calibration of tank model. DDS is designed for calibration problems with many parameters，requires no complicated algorithm parameter to be adjusted，and automatically scales the search to find good solutions within the maximum model evaluations. Tank model with 27 parameters is applied to the actual case；and DDS algorithm is adopted to find optimal solutions. The calculated runoff roughly agrees with the measured values. Finally a comparison between finite element method(FEM) and tank model is conducted，which shows that during rainfall infiltration，the multi-tank model has advantages over FEM in the simulation process of predicting groundwater table. It is clarified that the multi-connected tank model is useful in groundwater table prediction of the basin especially when the slope stability analysis is necessary there.

The development of three-dimensional finite element method，which can be applied to the immiscible contaminant transport problems in the underground flows，for two-phase flow in porous media is developed. The fundamental theory and numerical discretization formulations are elaborated. The numerical difficulty brought about by the distinct nonlinearity of the temporal evolvement of saturation-dependent variables is overcome by the mixed-form formulation. The effectiveness of simultaneous solution(SS) method and its efficiency improvement are explained. Finally，two computational examples are given for verification of the correctness and demonstration of the preliminary applicability.

As a specific instability of rock slope，an antidip stratified rock slope is different from the sliding one，and the failure mechanism has not been clarified yet. It is clear that the flexural toppling behavior is influenced by the geological structure significantly，and the numerical method based on continuum theory does not seem to work well. It is aimed to discuss the flexural toppling mechanism by using a universal distinct element code(UDEC)，and to find out the critical parameters for the future large slope cutting. Firstly，a numerical analysis has been conducted to simulate the flexural toppling failure phenomenon，which happened in a construction site. Then，a series of numerical analyses have been carried out further in order to find out the critical geometrical parameters of the slope for flexural toppling prediction. A significant slip behavior is found between the blocks in the UDEC model；and typical flexural failure phenomenon is reproduced in the simulation. According to the numerical results，a thinner spacing of joints leads to a trend of flexural toppling in case of the same geometrical parameters of the dip angle and the gradient of the cutting slope. The toppling failure is related with an alternate relationship between the joint dip angle and the gradient of the cutting slope.

The seasonal rainfall and corresponding variations of groundwater status due to rainfall are important factors that can induce collapse，debris flow and landslide hazards at Ryukemitsu area，Kakoshima，Japan. The average annual precipitation is around 2 000 mm in the study area；and several collapse and debris hazards occurred due to the influence of groundwater，making a great damage to the surrounding roads and railways. Based on many years of observation data of rainfall and water level，the tank model of the study area has been established to provide a powerful data support for the monitoring and early warning systems.

In order to expand the applicability of the coupled fictitious stress method and displacement discontinuity method，an advanced numerical system FSM·DDM that can be applied to the problems dealing with rock bolting is developed. In the procedure，two line elements representing rock hole and rock bolt are taken into consideration. Basic condition of this system is displacement continuity over the hole length of two line elements which have the same geometry，i.e. the two line elements are overlapped. The condition mentioned above corresponds to the real condition that rock bolt surface completely adheres to borehole wall. Hence，the displacement difference between two ends of bolt element is equal to that of borehole element in the numerical procedure. The influential coefficients due to extension of line element are computed based on Kelvin solution. Then，the borehole line element(free element) is combined to the three-dimensional BEM system with rock bolt line element，and the combined system can be solved as a boundary value problem.

Aiming at the attenuation of stress wave traveling through the rock joints，the influences of joint geometrical shape and stiffness on the stress wave transmission coefficient are analyzed. According to the geometrical shapes，six joint models have been designed to simulate the different rough surfaces of fracture. UDEC is adopted to simulate the wave propagation of single fracture with the six models and different stiffnesses. The modeling results of the transmission coefficient of the fracture models are compared with the theoretical solutions. It reveals that a rough joint surface distinctly affects the stress wave transmission in the jointed rocks compared with a smooth plane joint and decreases the amplitude and velocity.

A series of uniaxial compression creep tests on dry，saturated sandstones，and the sandstones with hydro-physico-chemical influencing effects due to the circulating flow of different hydro-chemical solutions are conducted. Based on the test results，the strain versus time relations，instantaneous strains，creep strains and creep rates of dry and saturated sandstones under different stress levels are compared；and the hydro-physical influencing effects and mechanisms of saturated sandstone are derived. Furthermore，the differences of creep strain versus time relations，creep strains，instantaneous strains and creep rates of the sandstones with hydro-physico-chemical influencing effects due to the circulating flow of different hydro-chemical solutions are systematically and originally researched respectively. The influencing effects of ion concentrations and pH values of the different hydro-chemical solutions are revealed；and the corresponding mechanisms of hydro-physico-chemical actions are investigated. The research demonstrates that the creep behavior of saturated sandstone is more obvious than that of dry sandstone，while the creep behavior of the sandstones with hydro-physico-chemical influencing effects due to the circulating flow of different hydro-chemical solutions are larger than those of dry and saturated sandstones. The creep behavior of saturated sandstone is affected dominantly by the hydro-physical action. The creep behavior of the sandstones due to the circulating flow of different hydro-chemical solutions has both the hydro-physical and hydro-chemical influencing effects. The larger the creep behaviors of sandstones are，the stronger the ion concentrations of the hydro-chemical solutions are. This paper has a useful reference to the theoretical and applied research in the field of rock rheological mechanics and water-rock interaction.

In order to detect the deformation and development of deep rock strata，a FBG-GFRP-cement mortar- unconsolidated soil layer strain transfer system is formed；based on the theoretical analysis results of the strain transferring of FBG sensor，the effects of the mechanical parameters of optical fiber，middle layer and host material on the strain transfer rate are analyzed；and the FBG sensor used for rock deformation monitoring and the borehole parameters are designed，which provides a basis for engineering application. The results show that，in the monitoring of rock strata，the diameter of the borehole is adopted to be about 100 mm，the critical length of FBG sensor used in this system is 149.23 mm. This system is then applied to the settlement monitoring of Quaternary system unconsolidated soil layer in Jining coal mine No.3，it is shown that FBG sensors can be used to monitor strain change of unconsolidated layer.

Based on the typical coal and gas outburst of Datong mine in Songzao，the experiment of outburst coal¢s gas seepage under stationary gas pressure and different confining pressures is conducted by MTS815 mechanical testing machine and self-developed servo-controlled triaxial load system. The results show that the seepage velocity of outburst coal¢s specimen drops at first and rises later with increasing axial stress，but decreases and keeps stable after peak stress. The seepage velocity after peak stress decreases with the increase of confining pressure，and keeps stable after the confining pressure reaches 4 MPa. The complete process equation of seepage velocity-axial stress is built. The relationship curve of seepage velocity-strain，which reflects the change of gas gradient，is derived.

There are responses of slope under long-term cyclic load，and the degradation of mechanical capability of slope soils causes the slope to become unstable and trigger the movement. The dynamic responses of a highway slope under cyclic load are presented by a finite element numerical simulation method. The results show that the displacement，velocity and acceleration of the monitoring point on slope increase linearly with the increase of the maximum amplitude of cyclic load with a constant vibration frequency. However，the maximum response values of the slope under the cyclic load with a constant vibration amplitude are not proportional to the frequency，and there is a strong response in the frequency band of 4–5 Hz，approaching to predominant frequency of the slope. It is possible for the slope system under the frequency band of cyclic load to arise a disadvantageous resonance for the stability of the slope. It is of theoretical and practical significance to evaluate the long-term stability and durability of the highway slopes under dynamic load.

Time domain reflectometry(TDR) is increasingly used to estimate soil water content in field and laboratory tests. Errors arising from estimation of soil water content in field are analyzed and their sources are summarized as adhesiveness of expansive soils and gaps between tube and expansive soils. Based on these，three types of laboratory test are designed to quantitatively analyze the corresponding sources of the errors. It is shown that with high adhesiveness of expansive soils，the amount of bound water is large and dielectric constant of soil is small. The measured values of volumetric water content by TDR are smaller than those by oven dry，but there is a corresponding relationship between volumetric water content measured by TDR and that calculated from mass water content. Thus a linear regression equation is proposed to represent the calibration curve. Gaps generated from shrinkage of expansive soils can be divided into gaps around the tube and radial gaps. Errors dramatically increase as gaps around the tube exist. An air gap around the tube about 1 mm will result in an underestimation of 40% of soil water content，and the errors increase with the increase of soil water content. However，there is no obvious influence caused by radial gaps，which only results in errors less than 5%. The reason is that the measurement sensitivity of TDR probe rapidly decreases with the increase of measuring distance. Finally，the data from field monitoring are applied to examine the test results，and measures to reduce errors are put forward.

Consideration of structural robustness is one of the most important measures to guarantee the structural safety，especially to deal with unexpected events. How to evaluate the structural robustness quantitatively is one of the most challenging problems in structural engineering. A new method to calculate the importance coefficient of components in structural robustness evaluation is given，which focuses on the change of structure capacity after removing a certain component in the structure. From conception，the structural topological relation，the component stiffness and strength，and the effect of external loads are all considered synthetically. Besides，from mechanics，how the broken component influences the remnant structure are also described，which can be used to explain the physical meaning of the new coefficients. At the same time，from global point of view，the interaction between the structural property and the external load effects is considered. The loading process is completed until the structure becomes a mechanism，to some extent，which helps to establish the relationship between component importance and structural robustness. From algorithm，a method called perturbation is used. It bridges the structural stiffness matrix before removing some component with that after removing，by which the rearrangement and inversion of the structural stiffness matrix can be avoided. Instead，the dimension of the structural stiffness matrix in each stage is only decided by the number of the broken components. The inversion calculation is easy，which only needs to treat some specific large sparse matrices. Finally，as practical examples，two plane trusses are given. Comparing with some existing indexes of component importance，the internal relations between them are found，and the correctness and rationality are also proven.

As Wenchuan earthquake was of high magnitude and shallow seismic focus，it caused considerable damage and thousands of geohazards. After a field investigation and the interpretation of remote-sensing images and aerial photographs taken after the earthquake，11 308 earthquake-induced geohazards have been obtained；and the general distribution situation of the geohazards has been learnt. Then，the distribution of these geohazards was investigated statistically using GIS techniques to determine how the occurrence of geohazards correlates with distance from the coseismic fault，slope steepness，elevation and rock type. The main results of this research can be summarized as follows. (1) The geohazards triggered by earthquake show the feature of zonal distribution along the coseismic fault and linear distribution along the rivers. (2) The distribution of earthquake-induced geohazards has marked hangingwall effect，for the geohazard concentration in the hangingwall of coseismic fault is obviously higher than that in the footwall and the width of strong development zone in the hangingwall is about 10 km. (3) the slope steepness is a main factor which controls the development of earthquake-induced geohazards and a vast majority of geohazards are distributed within the range of 20° to 50°. (4) The earthquake-induced geohazards have corresponding relationship with the elevation and micro-landform；for most hazards occur in river valley and canyon section below the elevation of 1 500 to 2 000 m，particularly in the upper segment of canyon section (namely，the turning point from the dale to the canyon). Thin ridge，isolated or full-face space mountains are most sensitive to the seismic wave，and have striking amplification effect. In these areas，collapses and landslides are most likely to occur. (5) The research also shows that different lithologies have no marked corresponding relationship with the development of geohazards，but it determines the types of geohazards. Usually，landslides occur in soft rocks，while collapses occur in hard rocks.