In comparison with fracture network flow model，fractured porous flow model，which is also called as dual medium seepage model，assumes that the fractures and the blocks cut by fractures are all permeable. With this kind of model，only the determinate bigger fractures are considered in fracture network simulation，and the rock blocks and their inner stochastic small fractures can be treated as continuous porous media. So the fracture quantity can be decreased and the calculation capacity can be increased. Therefore，this kind of model has a significant development prospect in discontinuous rock mass fluid flow model. At first，the problems of fractured porous flow model are discussed. Then，two kinds of solution methods are summarized，which are called as global solution method and flow exchange method，respectively. In the global solution method，the fractures are considered as media with definite widths and modeled with solid elements. The conductivity matrices of fracture elements and block elements are incorporated to form the global conductivity matrix. The fracture solid elements are obtained by expanding fracture nodes in calculation codes，and needn?t to be generated in meshing. In the flow exchange method，the fluid flow of the fracture network system and the rock block system are calculated separately by forming conductivity matrices and flow functions respectively. Then，by means of flow exchanges between these two systems，the calculation results can be iterated with the balance of flow and the unique hydraulic head in one node. It is pointed out that the flow exchange influences only the flow balance function of the downstream node. At last，the characteristics of these two methods are contrasted by means of cases study. Additionally，arbitrarily shaped loop triangulation method without adding any node is put forward.

Underground powerhouse caverns of Guandi Hydropower Station have the characteristics of high geostress and widely distributed discontinuities in hard surrounding rocks. Based on the characteristics analysis of geostress，rock mass structure and the conclusions derived from the monitored deformation data and the three-dimensional numerical simulation results，the deformation and failure characteristics of rock mass are summarized. The countermeasures for general layout design，excavation support design，construction of powerhouse caverns under high geostress condition are proposed based on systematical summarization. Following proposals are made for high geostress condition，such as the direction of the maximum principal geostress and the main discontinuities in the surrounding rock should be taken into account when the longitudinal axis of the chamber is chosen；adopting larger distance between the main chambers；adopting larger ratio of height to span of the top arch；adopting reasonable methods and sequence for excavation；improving the strength grade of shotcrete；delaying concreting the rock wall crane beam and the lining of busbar tunnels；determining reasonable initial prestress of the anchor cables. Also，for surrounding rock where rockburst is likely to take place，it is suggested that the initial steel fiber shotcrete with a thickness of 50 to 60 mm should be sprayed firstly；and then to install the systematical anchor bolts；finally to implement the designed remaining shotcrete with wire mesh. The above-mentioned proposals provide great guiding significances and application values for design and construction of similar underground powerhouse caverns under high geostress condition.

Loading rate has an important influence on rock mechanical properties. The influence degree is closely related to the microstructure of rock，loading and unloading paths and states，etc.. Based on the uniaxial compression tests of coarse crystal grain marble with nine strain rate levels in range of static loading rate，the influences of loading strain rate on stress-strain curve，failure pattern，strength，elastic modulus，deformation modulus and strain energy dissipation and release of the marble are investigated；and the energy mechanism of rock damage evolution is discussed. The initial cracking stress and critical dilatancy stress of rock specimens under different loading rates can be obtained by the relations of total volumetric strain and crack volumetric strain with initial cracking stress and critical dilatancy stress. The loading strain rate of about 1×10－3 s－1 is the dividing point. When the strain rate is less than the value，a certain plastic yield or flowing section near the peak of stress-strain curve is still present；but when the strain rate is more than the value，the fold line type near the peak of stress-strain curve is present. The fracture pattern of rock specimen changes from tension-shear to tensile rip and even rip-ejection with the increase of loading strain rate. Generally，the initial cracking stress，critical dilatancy stress，and uniaxial compressive strength increase with the loading strain rate；and the initial cracking stress and critical dilatancy stress are more closer to the peak strength. But when the loading strain rate is 1×10－4–1×10－3 s－1，a relative low value area is present for all values mentioned above，which is related to the microstructure of coarse crystal grain marble. The correlations between the initial cracking stress，critical dilatancy stress，elastic modulus and deformation modulus and the uniaxial compressive strength are linear. Under uniaxial compression，the more the energy dissipation before peak strength is，the higher the strength is；and the more the energy release after the peak strength is，the stronger the tensile through fracture characteristic is，and the more the fractured blocks are. The energy dissipation makes rock damage and the strength loss；and the energy release makes the macrofracture surface be run-through，inducing integral damage.

In order to better apply the technique of quasi-parallel cutting blast，based on similarity theory，the similarity criterion of model test of quasi-parallel cutting is established. The physical model tests of quasi-parallel cutting are carried out. Taking the face spacing，array pitch and angle of main cut holes as the key factors，the orthogonal tests are conducted. The results of range analysis show that：(1) The face spacing of main cut holes has the maximum effect on cut depth，next is the angle，and the minimum is the array pitch. (2) For cavity volume，the face spacing of main cut holes has the maximum effect，next is the array pitch，and the minimum is the angle. The results of variance analysis show that：(1) The face spacing of main cut holes has a very significant effect on cut depth，the angle has a significant effect on cut depth，while the array pitch has no effect on cut depth. (2) The three factors all have very significant effects on cavity volume. Besides，the model tests are conducted under the condition that the angle of main cut holes is greater than 85°. The test results show that the influence of angle of main cut holes on quasi-parallel cutting blast is very apparent. Meantime，the test results prove the analysis of corner span between quasi-parallel hole and the free face. The optimization blast parameters of model test are obtained as following：the face spacing of main cut holes is 150 mm；the array pitch of holes is 70 mm and the angle of main cut holes is 83°. The good blast effects are achieved by using the transformation scheme from the above scheme in field engineering.

Jintan bedded salt rock caused by mechanical and chemical deposition actions is structured under shallow lacustrine-lagoon facies-evaporite rock facies geological environments. However，Qianjiang bedded salt rock，whose lake basin environment is perennial deep water bedded salt lake，is formed by mechanical deposition action under the deep-water lake，oxygen lack and calm water environments. So，the interfaces between these two types of salt rocks are different. According to the characteristics of interfaces between Jintan and Qianjiang salt rocks，the uniaxial compression tests，shear tests and triaxial compression texts are carried out to investigate the interfaces of typical Jintan and Qianjiang salt rock specimens；and the complete stress-strain curves and their mechanical significations are deeply analyzed. Simultaneously，the specimens failure characteristics are also investigated. It is shown that：(1) Both of the two kinds of salt rock specimens present good ductility and the collapse failures don′t occur. (2) The cracks are generated mainly around the interfaces. The interface of Qianjiang salt rock plays a prominent role in limiting the deformation of the samples compared with the Jintan′s. (3) The peak shear stresses of both interface salt rocks are almost equal to the pure salt rock′s，which indicates that the shear failure of interface salt rocks is decided by the mechanical behavior of pure salt rock. The results could provide some references for selection and construction of gas storages.

Experiments are carried out to study sandstone mechanical properties after high temperature under static and dynamic loadings by the SHT4206 electro-hydraulic servo-controlled testing machine and split Hopkinson pressure bar(SHPB) equipment，respectively. The differences of rock failure mode，peak strength and peak strain after high temperature under static and dynamic loadings are analyzed and compared systematically. The effects of temperature on rock mechanical properties are investigated from microcosmic angle. The results show that：(1) The dynamic and static mechanical properties of rock are different evidently. With the increase of temperature，the failure mode of rock exhibits splitting failure with brittle fracture under static loadings while the rock failure mode is tensile fracture under dynamic loading. (2) The peak strength decreases evidently with the increase of temperature in a nearly linear way under static and dynamic loadings. The average peak strength decreases from 126.37 to 64.76 MPa in an extent of 48.8% under static loading，as well as from 176.3 to 83.1 MPa in an extent of 52.9% under dynamic loading. (3) The peak strain increases with the increase of temperature under static and dynamic loadings. Thermal stress and variation of microstructure induce different mechanical properties of sandstone due to the effect of temperature. The different modes of internal crack propagation and formation of microcracks appear due to different loading methods，which results in the difference in resistance of deformation.

Different from land tunnels，the subsea tunnels are located deeply under the sea，so the groundwater treatment is the key issue during tunnel construction. Simultaneously，water inflow control and calculation of water load acting on lining structure are the core issues. The external water pressure on lining will be reduced remarkably with low discharge by adopting the design discipline of blocking groundwater and limiting discharge. So the design of lining structure in subsea tunnels is more economical. Based on the correlation theory of groundwater hydraulics，a calculation methods of water load acting on composite lining and water inflow in subsea tunnels is derived. Taking Xiang′an subsea tunnel in Xiamen for example，the influences of variable parameters of primary support，secondary support and grouting circle on water inflow and external water pressure are then expounded by using theoretical analysis and numerical simulation. Subsequently，the program and method for choosing economic and rational parameters of grouting circle are put forward；and the reasonable parameters of grouting circle for Xiang′an subsea tunnel through the weathered deep slot F4 are given，which gets satisfying effects. The results provide references for tunnel waterproofing and drainage system design in high water pressure and water-enriched regions including subsea regions.

Traditional slope reinforcement measures adopt slope surface reinforcement such as anti-slidfing piles and cables，in which the depth from the surface to the inside of the slope is less than 80 m. While treatment measures aiming at large-scale potential sliding body with deep weak slip surface are not widely accepted yet，and the passive measures like avoidance and unloading are often employed. Taking the left high slope of Jinping I hydropower station as a case，the reinforcement principle and working conditions of deep embedded concrete shear resistance structures used for treatment of large engineering slope are analyzed；and the design methods of the shear resistance structures，including arrangement of tunnels trend，selection of cross-section types of tunnels，excavation ways and construction procedures，layouts for consolidation grouting holes around the tunnels and segmental and dislocation lamination pouring of backfill concrete，are systematically presented. Three-dimensional numerical results and field practice indicate that the proposed design method for embedded concrete shear resistance structures with the effects of replacement，adding strength and shear resistance for reinforcement of the rock slope with deep slip surface is valid. The proposed design method is not only helpful to ensure the safety of the left high slope，but also provides valuable experiences for the reinforcement of the high slopes of similar projects.

According to experimental investigation on permeability property of coal containing gas，the change rule of permeability of coal containing gas is analyzed systematically under complex stress paths. Quantitative and qualitative relations of the permeability of coal containing gas with axial pressure，confining pressure，gas pressure，loading-unloading of confining pressure and complete stress-strain process are established respectively. The controlling mechanism and change law of permeability of coal containing gas under different stress paths are discussed. The results show that the stress path has an important impact on the permeability of coal containing gas：(1) The permeability of coal containing gas decreases with the increase of axial pressure and confining pressure，while increases with the increase of gas pressure. (2) The relationships of permeability of coal containing gas with axial pressure，confining pressure and gas pressure obey approximately an exponential law. (3) During the loading-unloading process of confining pressure，the permeability of coal containing gas is damaged to a certain extent and this damage can be represented by the maximal damage rate and damage rate of permeability. At the same time，the results show that the second-compacting effect of coal containing gas will happen under the condition of triaxial compression. (4) During the complete stress-strain a test process under triaxial compression，the change trend of permeability of coal containing gas versus strain curve is V-shaped approximately. The permeability of coal sample decreases first，then increases with strain，and reaches its maximum finally. The increasing amplitude is less than the decreasing amplitude.

An experimental investigation on three-dimensional(3D) surface crack under biaxial compression is conducted to investigate the growth of wing crack and anti-wing crack. A digital speckle camera is used to record the growth process of cracks during loading process. The images captured from the digital speckle camera are used for digital speckle correlation analysis to study the strain field of 3D surface crack. From the experiments，it is observed that the anti-wing crack initiates away from the crack tip region and then propagates towards the crack tip. The stress and the stress intensity factors along crack front are analyzed by using the finite element method. 3D wing crack growth pattern is revealed by the mixed-model fracture criteria. The theoretical analyses indicate that the wing crack propagation can be predicted by the maximal circumferential stress criterion   and maximal circumferential strain criterion  . The strength failure analysis is also conducted in the anti-wing crack area. The anti-wing initiation and propagation can be predicted by the Mohr-Coulomb strength theory. The whole fracture and failure process of the 3D surface crack is analyzed by both experiments and theories.

Effects of torsional shear frequency，input voltage and specimen torsional stiffness on the torque factor are systematically investigated on the basis of a number of torsional shear tests on six aluminum calibration bars using the combined torsional shear resonant column apparatus. Results indicate that the torque factor of this type of device slightly decreases with increasing torsional shear frequency and input voltage，but significantly increases with increasing torsional stiffness of specimen，due to the inherent design limitation of the electromagnetic drive system. When the constant torque factor obtained from the traditional calibration method，which is suggested by the manufacturer，is employed to analyze the shear modulus of calibration bar，testing result is significantly underestimated with the error of 14% for the greatest stiffness calibration bar(Bar #6)，and overestimated with the error of 25% for the smallest stiffness bar(Bar #1). Therefore，a new calibration procedure is proposed to overcome the error induced by the inherent design weakness of the drive system. It can minimize the testing error within 3% for torsional shear tests conducted by this type of resonant column device.

In order to understand the relationship between acoustic emission(AE) parameters and mechanical failure mechanism of salt rock，and to further reveal the damage evolution law under different loading strain rates，the damage evolution law and AE parameters of salt rock are studied under three kinds of loading strain rates of 2×10－3，2×10－4，2×10－5 s－1 by AE technique. The results show that：(1) The change laws of stress-strain curves of the three kinds of loading strain rates are similar. With the increase of loading rate，the elastic limit strength increases slightly，the peak strength and its corresponding strain value vary slightly，and the time of reaching the peak strength decreases linearly. (2) The slower the loading rate is，the more loosely the rock is crushed，which results in more cracks and more cumulative numbers of AE signal. (3) The faster the loading rate is，the larger the AE frequency is，and the brittle failure characteristic is more evident. The change range of AE signal frequency reflects the crack generation velocity and the damage evolution process of salt rock under different loading strain rates. The AE counts reflect rightly the stress-strain curve of salt rock before peak strength. The change of transmittance of salt rock can reflect the damage distribution regions and damage cumulative ranges to some extent under uniaxial compression. Based on the AE counts，the damage evolution equation is established，which can rightly reflect the evolution of salt rock under low loading strain rate.

Based on the project example of Hulusu auxiliary shaft of Hujierte coal mine in Erdos，the construction technology and monitoring method of the first new single-layer shaft lining  in bedrock during freezing sinking in China are described. The main technical difficulties in shaft lining construction process are analyzed in detail and the concrete quality control standards of shaft lining are given. The field monitoring results show that：(1) The steel stress and concrete strain of new single-layer shaft lining are the combined action results of bedrock freezing pressure and shaft lining temperature during shaft sinking. (2) The change process of steel stress and concrete strain can be divided into 4 periods，i.e. OA，AB，BC and CD period. (3) During shaft sinking，the maximum tensile stress of vertical steels is 35.5–70.8 MPa and the maximum compressive stress of vertical steels is －7.0–－45.0 MPa；and the circumferential steels keep in compression condition all along and the maximum compressive stress is －41.7–－101.0 MPa. (4) The maximum vertical compressive strain of concrete is －190.5–－458.0 με and the maximum circumferential compressive strain is －590.4–－799.1 με. The maximum circumferential compressive strain of concrete is 1.3–4.2 times of the vertical direction. (5) It is recommended that the vertical steels should be designed to withstand the load of 12 m height of the new single-layer shaft lining. (6) In conclusion，the new single-layer shaft lining of Hulusu auxiliary shaft is safe during shaft freezing sinking.

The classical Nishihara model is composed of the Hooke body，viscoelastic body and viscoplastic body，which can hardly describe the rheological feature of nonlinear accelerating creep of rocks. By connecting a nonlinear viscous dashpot with a strain trigger and the classical Nishihara model in series，a modified Nishihara model is obtained and a 3D creep constitutive equation for rocks under constant stress is deduced. Through fitting with a rheological curve from experiments on red sandstones from Wanzhou in the Three Gorges reservoir area，parameters of the modified Nishihara model are derived. Comparison between the actual experimental data and the fitting curve of the modified Nishihara model shows that not only an adequate reflection of primary and steady creep stages，but also a well depiction of accelerating creep stage can be obtained. Accelerating creep is a key stage for landslides forecast. So success of the modified Nishihara model in representing this stage contributes greatly to landslide forecasting.

The major problem in determining the shear strength of rock joints is how to measure and then express the joint roughness with a number or a mathematical function according to joint morphology. Joint roughness coefficient(JRC) is probably the most commonly used method to measure roughness of rock joint surfaces. The method of evaluating JRC of joint is by visual comparison of measured profiles against a set of standard JRC profiles produced by Barton and Choubey. However，JRC estimation by visual comparison is prone to subjectivity and based on the analysis of only a single profile in the direction of shearing and usually underestimates joint roughness. The right method should be based on three-dimensional topography of joint surface. During shear tests，it is observed that the common characteristic among all the contact areas is that they are located in the steepest zones facing the shear direction. There is a parabolic function relationship between the potential contact area and the apparent dip angle. This function is a manifestation of real three-dimensional joint surface morphology information. Based on 42 direct shear test results，the relationship between peak shear dilatancy angle and three-dimensional morphology parameters is presented，and then a new shear strength criterion is proposed. All the parameters are determined according to joint topography. The new criterion follows the standard form of Mohr-Coulomb formula and has a explicit physical meaning. Finally，priority between two shear strength criteria is analyzed and how to use the new criterion is also suggested.

Considering the sequence of two-tunnel excavation，converting the underground space of tunnel to the case of elastic half-space under plane strain，an analytical solution is presented for stress and displacement of twin- tunnels with arbitrarily shape and size using analytic continuation method and Schwarz alternating method in an elastic half-plane. Because the depth is larger than the size of the tunnel，thus the effect of gravity gradient is ignored，and gravity loads are simplified as uniform normal loads along far-field boundary. As a special case，a close solution for stress and displacement field around circular twin-tunnels at great depth considering the influences of lining forces of tunnels is given. Circular twin-tunnels are subjected to uniform internal pressure and their construction sequences are properly taken into consideration. Comparison between the results of numerical analysis by two-dimensional finite element method and those from the closed solutions indicates that the closed solution is reliable and applicable for the stress and displacement field around the twin-tunnels at great depth.

Using self-designed visual model devices，macro-meso tests on pile tip penetration in layered media are carried out to study the impact of upper weak layer on variation of lower sand around pile tip. It shows that the critical depth of pile tip resistance exists in layered medium. Because of different tendencies of frictional resistance，the depth of pile tip penetration in layered medium is less than that in pure sand in order to reach the ultimate pile tip resistance；the layered media present different variations of particle?s directionality in meso side. Three-dimensional non-circle particle flow code numerical simulation program is developed to simulate the laboratory model tests of pile tip penetration in layered medium. The results of simulation have a better consistence with laboratory tests，building a foundation for the further study of macro-meso mechanism of soil variation around pile tip in the course of penetration.

By analyzing the physical process and mechanism of the dynamic residual strain of unsaturated loess，critical influence parameters are investigated. By contrast with laboratory data of unsaturated loess specimens under dynamic/static triaxial tests，consequently，a magnitude estimation method with two individual formulas is proposed for the dynamic residual strain of nature loess. The analysis results show that the dynamic residual strain of unsaturated loess could be described as a consolidation response of generalized solid-phase-media of loess mass under external dynamic loads. Meanwhile，critical parameters influencing the dynamic residual strain of unsaturated loess include two aspects，which are the strength and volume characteristics of the generalized solid-phase-media and the external dynamic loads features，respectively. For above-mentioned critical characteristics，the strength could be figured by cohesion and internal friction angle，both expediently obtained through laboratory geotechnical tests，while the volume could be described by void ratio，which reflects the under-compacted status of loess mass. Generally，the former shows the endurance capacity of loess to resist external dynamic loads and the latter describes the settlement capacity of loess under an external dynamic load. In the analysis of magnitude estimation method for dynamic residual strain of unsaturated loess proposed here，the results of physical mechanism and critical influence parameters are considered comprehensively. It will be helpful，therefore，to establish a reasonable and practical constitutive model for plastic deformation of unsaturated loess under dynamic/static loading.

For resolving controversy of separate and combined calculation of water and earth pressures and theoretically proving that combined calculation of water and earth pressure is reasonable under some circumstances，it is necessary to establish a unified algorithm that is able to integrate separate and combined calculations in a theoretical framework. This paper establishes a unified calculation theory of water and earth pressures through the ideal model test and verifies its scientificity at the same time. Based on the ideal model test，a new strength theory is proposed that can be applied to the unified algorithm. From the calculation example we can see slight differences between the results of new and traditional methods. This new unified algorithm can be used to calculate water and earth pressures separately for sand and change to combined calculation for clay. Moreover，this can also be applied to calculate the water and earth pressures for aquitard strata like clayey silt and silty clay. It provides a theoretical basis for the calculation of load on underground structures.

Based on the bursting modes such as overall heaving，water and sand inrushing in contact between soil and underground structures and surface boiling，judgment methods that determine whether inrushing happens were studied by numerical and theoretical analyses. Results show that the rupture surface modes include vertical plane and circular plane with the angle of   with impermeable layer. Then the shear force formula of rupture surface was established and a quantitative calculation method to determine whether overall heaving occurs was gained through theoretical derivation. Based on the mechanism of surface boiling and the index of tensile-shear failure，the judgment formulus that determines whether surface boiling happens was gained. By comparison，it is shown that the calculated values have a good agreement with the experimental values.

Compression tests for structured clay in Zhanjiang were conducted to obtain the evolution of soil microstructure in deformation process. Natural soil samples and soil samples after compression tests were prepared for SEM and MIP tests by lyophilization. Three-dimensional porosity was calculated based on gray scale，the evolution of microscopic pores in compression process was qualitatively and quantitatively analyzed. The results show that，compared with two-dimensional porosity based on binary image，the three-dimensional porosity has advantages of explicit physical significance，simple calculation method and high accuracy. Pores with diameters of 1.0–0.1 μm were dominant in natural clay，whose volume took up 73% of total pore volume. When P＜?k，each pore size changed little. When P＞?k，fine pore content firstly increased，subsequently decreased with the increase of the pressure. In the compression process，a positive correlation between the sensitivity of each pore size to external forces and pore volume content was found. The distribution density of the fine pores might be exaggerated while the one of macro-pores might be underestimated in MIP for the bottleneck effect during MIP test. The evolution of microstructure of structured clay in the compression process might be divided into three stages：fine tuning stage，damage stage and solidification stage. The study is helpful for good understanding of deformation mechanism of soil，and provides a scientific basis for engineering design of structured clay.

Since the concrete lining has viscoelastic properties，the whole process of its creep can not be described well by the previous theories such as elastic curved beam，elastic shell and so on. In this paper，the soil and concrete lining are considered as saturated viscoelastic porous medium and viscoelastic material with fractional derivative constitutive relation，respectively. The coupled vibration characteristics of the saturated viscoelastic soil and the lining system with a deep circular tunnel are investigated in frequency domain. Based on the Biot?s theory and viscoelastic theory，analytic solutions of displacement，stress and pore water pressure of the saturated soil and the lining under harmonic loads are obtained by displacement potential function，respectively. Besides，the expressions of undetermined coefficients are presented according to the inner boundary conditions of the lining as well as the displacement and stress continuous conditions at the interface between the saturated soil and the lining. At last，the effects of the physical and geometric parameters of the saturated soil and the lining on the system dynamic behavior are investigated. It is shown that the dynamic characteristics of the saturated viscoelastic soil and fractional derivative viscoelastic lining system are obviously different from those of the saturated viscoelastic soil and classic viscoelastic lining system. Furthermore，the response amplitudes decrease gradually as the damping ratio of the soil skeleton increases.