In order to break through the experimental research bottleneck of hydro-mechanical coupling mechanisms of fractured rock mass reflecting the combined actions of rock mass characteristics，rock mass structure，initial stress state and stress path，a HMTS–1200 hydro-mechanical coupling true triaxial test system for fractured rock mass，consisting of high water pressure sealed test chamber system，loading and reaction system，high water pressure resistant deformation measurement system and high precision servo control system，is developed. The advantages of this apparatus are shown as follows：(1) based on the ideology of external sealed system，a high water pressure steel sealed test cabin with 1.6 m diameter is constructed to simulate the water pressure environment of fractured rock mass and the rock mass specimen and mechanical test apparatus can be placed in the chamber to carry out tests，(2) the size of fractured rock mass specimen reaches 310 mm×310 mm×620 mm and a maximum axial load of 12 000 kN and a lateral load of 3 000 kN can be applied，and (3) the rock mass deformation under high water pressures can be measured directly by deformation sensors with 3 MPa water pressure endurance，0.001 mm resolution and less than 0.05% linearity. Hydro-mechanical coupling tests under different stress states were performed. The test results show that the mechanical effect of the water pressure and the deformation response of rock mass specimens are related to the structure characteristics of rock mass，initial stress state and the path of water pressure. The water pressure acting on the specimen presents two types: an additional surface force applied on the surface of the specimen and compressing the specimen，and a seepage pressure produced by water infiltration into the fracture，reducing the effective stress of the fracture surface，and causing shear dislocation of fractures and dilating deformation of the rock specimen. The successful development of this apparatus can provide a new means for researches on complicated hydro-mechanical coupling problems and the engineering applications of rock bank deformation and induced landslides related to water impounding and operations of high dam reservoir.

Hydro-mechanical coupling analysis has been a focus and difficulty in the study on the stability of deep buried diversion tunnels in hydropower station. Based on the effective stress principle of porous media，an improved model regarding the dynamic evolution of porosity and permeability of saturated rock with respect to volumetric strain is derived，which can realize the real hydro-mechanical coupling analysis in the process of failure of surrounding rock. Being introduced into the code ABAQUS through the secondary development of user-defined subroutines，the evolution model is applied to a large deep buried diversion tunnel. The calculation results by the proposed evolution model are compared with field monitoring data and traditional hydro- mechanical coupling calculation results in terms of the permeability distribution and displacement in the surrounding rock，and it is shown that the proposed model is more precise and more practical. In order to study the influence of filling and draining water on the stability of the diversion tunnel during operation period，a numerical simulation with 5 calculation steps is conducted. Compared the traditional case taking the permeability as an invariant，for the surrounding rock，the pore water pressure after the periods of filling and draining water decreases more rapidly from the border to deep ground，the displacement at the roof is much larger by up to 100% and larger by 180% to 200% at the floor，and the scope and extent of the plastic zone are far greater. For the lining of the tunnel，the tensile stress in the linings with a constant permeability increases by approximately 11% from filling water to draining water while the calculation result by the proposed evolution model increases by up to 35% with a larger value，which should be paid more attention.

Liquid nitrogen(LN) fracturing，as a novel waterless fracturing technology，is expected to provide a new approach for shale gas development. To reveal the cracking characteristics of shale due to LN fracturing， laboratory simulation experiments were performed on shale samples utilizing a self-designed experimental apparatus. The effects of shale initial temperature and LN treatment on cracking characteristics and fracture pattern of shale were researched，and the shale cracking mechanism induced by LN fracturing was explored. Finally，a novel fracturing technology with LN was proposed based on the experimental results. The investigations show that the thermal shock induced by LN remarkably affects the breakdown pressure and the cracking mode of shale. As the shale temperature increases from room temperature(25 ℃) to 80 ℃ and 150 ℃，the breakdown pressure decreases by 22.58% and 32.26%，respectively. During LN fracturing experiments，the samples at room temperature were fractured along the original weak plane，whilethe cracking mode of 80 ℃ and 150 ℃ samples transforms to tensile rupture along the borehole axis. For LN cool-treated samples，the cracking mode mainly presents in the form of local fractures，whose complexity increases with the sample initial temperature. For the samples under LN cooling condition，the obvious gas leakage phenomenon was observed on the sample surface due to the increase of the permeability of shale. The cracking mode of the samples under LN cooling condition transforms to local fracture with low aperture. Under LN cooling condition，the breakdown pressure increases compared with original samples. However，the re-open of existing cracks induced by LN cooling could make the fluid permeate into the shale more easily，which is beneficial to the pressure transmission. The multiple cracking effect on shale can be generated by LN fracturing，including thermal shock，cryogenic damage，low-temperature cracking and pressure-induced cracking. The alternate treatment of gaseous nitrogen fracturing and LN cooling was proposed to make full use of the low-temperature cooling effect of LN.

The mechanical analysis of surrounding rock with arbitrary shape holes is of great significance for the safety of tunnel construction. In traditional analytical methods，the Schwarz alternating method is usually used to solve the multiple-hole problem，but its accuracy and efficiency are seriously affected by the number of iterations. Therefore，the Schwarz alternating method is not suitable for engineering applications. To solve this problem，in this paper，a non-iterative analytical method for the mechanical analysis of surrounding rock with arbitrary shape holes was proposed based on the theory of multiple Laurent series expansions. This method introduces several groups of analytic functions to accurately reformulate the stress and displacement fields of the multiply-connected domain，and establishes the stress and displacement boundary conditions by performing the conformal mapping on each hole individually. The conformal transformations of different holes are independent of each other，which makes it possible to handle the complex boundaries. Finally，the Fourier transform technique is used to transform the boundary conditions into the frequency equations，and then all unknowns in the analytic function can be uniquely determined. The proposed method can directly obtain the accurate solution of stress and displacement without any iteration，and hence is simple，efficient and suitable for engineering applications.

The effects of initial normal stress(0.02–8 MPa) and roughness coefficient JRC(12–18) on shear stress，normal displacement，normal stress and shear wear characteristics of fracture surfaces were investigated. The results show that，during the whole shear process，the normal displacement-normal stress fitting relationships of fracture surfaces present a group of parallel lines，with a constant normal stiffness boundary of 10.8 GPa/m. With increasing initial normal stress and JRC，the normal stress of fracture surfaces presents an increase，and the initial peak shear stress respectively increases by 6.201–9.974 times and 22.70%–55.76%. The normal displacement of fracture surfaces declines as the initial normal stress increases，while the dilatancy deformation tends to be intensified with increasing JRC due to gradually significant “climbing effects” along the asperities of the fracture surfaces. The peak surface resistance index decreases with increasing the initial normal stress，while increases by 10.82%–36.46% with increasing JRC. As JRC increases，the strength envelope of the initial peak shear stress becomes steeper. At the shear wear stage，the normal stress-shear stress paths can be will described using a linear function，and the fitting curves tend to be gentle as the initial normal stress increases. The binaryzation calculation results after shear tests indicate that，with increasing the initial normal stress and JRC，the ratio of the shear area on the fracture surfaces increases by 1.032–1.799 times and 8.63%–71.81%，respectively. The shear wear characteristics tend to be significant.

In order to study the dynamic tensile mechanical properties and energy dissipation mechanisms of layered slate under saturated conditions，Brazilian disc split test was performed by using SHPB system with a 50mm diameter rod，and the influence of water，bedding angle and loading rate on the dynamic tensile strength，failure mode and energy dissipation of slate was studied. The research results show that the dynamic tensile strength and the dissipated energy density of slate increase with increasing the loading rate. When the loading rate is lower than 395 GPa·s－1，the tensile strength of saturated slate is lower than that of dry slate，and the strength of the rock mass is softening. However，when the loading rate is higher than 395 GPa·s－1，the tensile strength of saturated slate is higher than that of dry slate，and the strength of the rock mass presents a strengthening phenomenon. Saturated slate shows tensile failure mode and combined tensile and shear failure mode when the loading angle q is in the ranges of 0°–15°and 30°–90°. When q = 75° and 90°，the dynamic tensile strength of saturated slate increases faster as the loading rate increases，and at the same time，the energy dissipation and the dissipation rate are the highest. The dissipated energy density of saturated water slate is higher than that of dry slate under impact loads.

The permeability of the parent rock(type I granite)，hydrothermal fluid backfill(type II granite)，A-type fractured-subsequently-filled granite(cementation interface between the backfill and the parent rock laterally positioned through the specimen，type III granite) and B-type fractured-subsequently-filled(granite cementation interface between the backfill and the parent rock longitudinally positioned through the specimen，type IV granite) under high temperature and triaxial stresses was studied in this paper. The threshold temperatures of permeability change of types I，II，III and IV granite are 300 ℃，200 ℃，300 ℃ and 250 ℃，respectively. When the temperature is lower than the threshold，the permeability of four kinds of granite almost unchanged. When the temperature exceeds the threshold，however，the permeability of four kinds of granite increases rapidly by 1，3，2 and 3 orders of magnitude respectively，and the permeability magnitude of types II and IV granites reaches 10－1 mD at above 450 ℃. The micro-structure and thermally induced fracture number of fractured-subsequently-filled granite under the action of high temperature were observed by a microscope. It is found that the permeability of types I and III granite increases because of the penetration of fractures with a length greater than 200 μm after 300 ℃，and that the low strength and deteriorated mechanical property of the backfill due to dissolution are the main reasons for the permeability of types II and IV granite to be significantly higher than that of types I and III granite. Through the analysis of the model of convection heat transfer between water and rock mass，it can be seen that the reservoir construction in fractured-subsequently-filled granite can greatly reduce the construction cost，increase the water-rock heat exchange area and improve the heat exchange efficiency. The research work provides a new technical and theoretical thinking for deep HDR geothermal exploitation.

The shock damage of brittle rock under high temperature generally reflects its cracking characteristics，which is of significance in practical engineering of dry hot rock energy resources. In this paper，the parameters of the HJC constitutive model that can reflect the temperature effect are obtained by simulating the granite failure process with Hopkinson pressure bar under different temperatures. For a single blasthole，the granite damage and cracking characteristics under different temperatures are studied. The results indicate that the crush area around the blasthole is not sensitive to temperature changes under the blasting loading while the crack area increases substantially under 100 ℃ temperature but changes little between 100 ℃ and 500 ℃. Then keeping the blasting load peak(1 500 MPa) unchanged，the increase of loading rate has a great influence on the crack area at room temperature but a negligible influence at high temperature. And the increase of explosion load impulse or the action time can result in the expansion of crack area obviously，especially at a high temperature between 100 ℃ and 500 ℃. Therefore，to reduce the crush area and increase the crack area of surrounding rock during the dry hot rock cracking process，the low-detonation-velocity explosive is suggested to use for controlling the crush area. And raising the charge weight correspondingly to increase the load action time can increase the crack area for better cracking effect. Although the high ground temperature can affect the impact property，cracking effect induced by explosion will be enhanced.

The particle distribution of glutenite formations is often heterogeneous，which seriously affects the fracturing effect. To ascertain the hydraulic fracturing mechanism of glutenite formations is thus one of the hottest and most difficult points in current oil and gas reservoir development. Three kinds of downhole glutenite cores with different gravel particle sizes were selected，and hydraulic fracturing tests were performed under different confining pressures to analyze the hydraulic fracturing mechanism of glutenite. The results show that, when the confining pressure is low，the fracturing curve has obvious nonlinearity in the pressurization stage and the difference(Pb－Pi) between the rupture pressure(Pb) and the initiation pressure(Pi) is large，With increasing the confining pressure，the non-linearity of the fracturing curve and the value of Pb－Pi of glutenite with poor particle size sorting decrease rapidly，while the glutenite with good gravel particle size selection has a smaller change range and smaller value of Pb－Pi. The rupture pattern appears as revolving gravel under the low confining pressure. Crack propagation evolves from crack arrest to penetration for the glutenite with poor particle size sorting when the confining pressure increases，while for good particle size sorting，the fracture morphology has no obvious relationship with the confining pressure. Fracturing fluid filtration can induce crack initiation and injection energy can affect the mechanical mechanism of cracks encountering gravel. Change of the gravel particle size selection from poor to good directly affects the reduction of the fracturing fluid filtration rate，resulting in the decrease of the fluid loss，and the increase of the crack initiation pressure. When the confining pressure increases，the injection energy increases while the crack tortuosity decreases. Related research results are expeceted to provide theoretical basis for the reconstruction of glutenite formations.

Based on the recent advance of ambient noise in seismology and diffusing wave in acoustics，a novel method for monitoring the wave velocity change of rock mass inside slopes using diffusing wave induced by ambient noise is proposed，by which the ground surface vibration caused by ambient noise is monitored using seismometers. The real time wave velocity change of the underground rock mass can be obtained through the correlation of the diffusing wave. This method was applied to monitor the rock slope at the right band of the reservoir of the Pubugou Power Station in Sichuan Province. The results show that the rock mass wave velocity varies with the season and is affected by the nearby earthquake and precipitation. Specifically，the rock mass wave velocity increases with the temperature，decreases temporarily due to the earthquake and decreases continuously with the precipitation. Around 7 days prior to a local small landslide，abnormal wave velocity decrease was observed，and the velocity stayed at a minimum value till the catastrophic failure.

Granite is widely used in engineering for its superior mechanical properties. A multilevel parallel bonded-grain based model(Multi Pb-GBM) was proposed to revel the micro structure of crystalline granite，in which parallel bonded-grain model(Pb) was introduced to replace smooth joint model(SJ) to represent the grain boundaries. The bonded mode of the samples were clarified into three types including intra-grain contact，inter-grain contact inside one mineral and inter-grain contact between two different minerals. Parameters of the model were calibrated through uniaxial compression tests and Brazil splitting tests，and simulations were conducted to study failure modes and dynamic damage evolution of brittle granite rock under the influence of the grain size distribution coefficient. An intact fracture-monitored system was established based on Fish function，and the behaviors of the micro-fracture were discussed. The results indicate that the grain size distribution coefficient has an effect on the failure modes，tensile cracks are dominant in uniaxial and Brazil splitting tests，and that both UCS and UTS show an increasing tendency with increasing granite crystal size. The number of cracks at grain boundaries of different minerals is larger than that at grain boundaries inside the same mineral. With increasing the grain size coefficient，the number of cracks at grain boundaries gradually decreases while the internal fractures increase. The microcracks first appear at the third level contacts，followed by the fractures at the second level contacts，and then the number of first level cracks increases rapidly. During uniaxial compression tests，a transformation process from inter-grain fracturing with kalium feldspar-quartz boundary to intra-grain damaging within kalium feldspar-plagioclase occurs until macroscopic failure.

Based on the horizontal centerline(HC) of tunnel，an automatic extraction and deformation analysis method of tunnel cross-section information is proposed. Firstly，the point cloud data of tunnels are projected horizontally to extract the horizontal centerline. Considering the influence of the tunnel adjuncts and the absence of point cloud data on the accuracy of the HC extraction，a sliding window robust fitting method is proposed to extract the HC accurately. Then，the cross-section of the tunnel is extracted and the points of the central axis are fitted. Finally，the radial displacement of each part of the tunnel is calculated according to the central axis points and the design values. The overall deformation of the tunnel can be described intuitively through visual rendering. The results show that，with increasing the length of the tunnel，the fitting error of the HC of the tunnel by the traditional global fitting method gradually increases while tends to be stable by the sliding window robust fitting method，and that the sliding window robust fitting method can effectively avoid the horizontal centerline deviation caused by obstacles. After fitting the tunnel cross-sectional parameters according to the space circle model，the RGB color components are used to render the point cloud of the tunnel according to the radial displacement，which can reflect the deformation of the tunnel. The research work provides a basis for tunnel deformation monitoring.

Temperature has an important influence on pore water pressure and stress-strain relationship of soft clay. Through a self-developed temperature controlled triaxial apparatus，the development of pore water pressure and stress-strain characteristics of soft clay under three different temperature modes including constant temperature，heating and cooling were studied. Under the temperature rise and temperature drop modes，the effects of time interval and confining pressure on the dissipation of pore water pressure，stress-strain relationship，shear strength and elastic modulus of soft clay were emphatically studied. The results show that the dissipation rate and amount of pore water pressure increase with increasing temperature from 10 ℃ to 70 ℃ in constant temperature mode. In the heating and cooling modes，the pore water pressure shows a fluctuant decrease and the increases of the time interval and the confining pressure could promote the dissipation of the pore water pressure. In the constant temperature mode，the stress-strain mode changes from strain hardening to strain softening with increasing the temperature，the shear strength increases obviously，and the elastic modulus shows a trend of first decreasing and then increasing. In the heating and cooling modes，the stress-strain mode of soil is strain hardening，and the time interval and the confining pressure obviously have positive influence on the shear strength and the elastic modulus.

A non-orthogonal single yield surface model for clays and sands is proposed based on the critical state soil mechanics，while，and a state-dependent hardening rule including parameters of  and  is developed for the sub-loading surface by considering the effects of the stress level and the relative density. The proposed model is quite simple in the formula and is capable of describing the strain-softening and dilative features of over consolidated clays and dense sands. In the  plane，the relative position between the current mean effective stress and the critical state mean effective stress  is represented by the pressure state parameter，while the void difference between the current and critical states in the plane is captured by the density state parameter. Both  and  will approach zero once the material enters the critical state due to yielding. On the other hand，the generalized plastic potential function adopted in the proposed model is integrated by a high-order dilatancy rule，which is extended from the modified Cam-clay dilatancy rule. The plastic potential function contains a dilatancy related parameter a，whose value can be determined by fitting dilatancy curves with the high-order dilatancy rule. Besides，a two-parameter yield function can be developed by introducing an extra parameter into the proposed plastic potential function. Adjusting the value of d，both associated() and non-associated() plastic flow rules can be obtained. The deviation between the plastic flow direction() and the loading direction() increases as the parameter d increases，and at the same time，the strain vector is not normal to the yield surface. With the two-parameter yield function，the proposed model can consider the effect of the yield surface shape on the model prediction. Comparisons between the calculation results by the proposed model and drained triaxial test results of clays and sands show that the developed model can uniformly describe the behaviors of clays and sands. Moreover，adjusting the yield function shape can improve the accuracy of model prediction significantly.

The construction of subway connection channels in Hangzhou is mostly carried out by freezing method，which leads to uneven settlement during operation. In the whole range of frozen soil，the freezing conditions change with the relative relationship between the soil and the freezing pipe. Soil samples frozen under different freezing conditions were obtained using sample making instrument invented by the authors. Nuclear magnetic resonance(NMR) tests were performed to study the variation of pore size distribution curve of freezing-thawing soil under different freezing conditions, and the pore pressure，strain and stiffness of the samples were deeply explored combined with dynamic triaxial test. A concise pore pressure prediction model of soft clay under artificial freezing with clear physical parameters was established. The results show that, with decreasing the freezing temperature，frost-heaving brings about worse destruction of the soil structure. During freezing-thawing period，the confining pressure can effectively compact the framework structure of the soil and reduce the deformation under cyclic loads. The limit value of the pore pressure is linearly correlated with the area of medium pores of pore size distribution curve.

Current simplified analytical methods for predicting shield tunnel longitudinal deformation due to excavation commonly adopt elastic foundation model to consider the ground-tunnel interaction and hence，fail to reflect the nonlinear deformation characteristics of subsoils. Introducing nonlinear Pasternak foundation model for considering the tunnel-soil nonlinear interaction，in this paper，a differential equation for shield tunnel longitudinal deformation owing to overlying excavation is derived. The differential equation is transferred into matrix-vector form according to the finite difference method，and then the numerical solution for shield tunnel longitudinal deformation induced by excavation is solved using the Newton¢s iteration method. The applicability and feasibility of the proposed method is verified by three-dimensional finite element simulations and two field cases. The results show that，when the longitudinal heave of shield tunnels induced by excavation is smaller，both the simplified analytical methods based on the Winkler and Pasternak elastic foundation models and the proposed method provide good predictions for shield tunnel longitudinal heave，while that，for a considerable large longitudinal heave of shield tunnel，the proposed method based on the nonlinear Pasternak foundation model always offers a more reliable prediction of the heave of shield tunnels but the simplified methods give a significant underestimation.

Based on the analysis of confining pressure variation of shield tunnels caused by foundation pit excavation，a model for evaluating the transverse additional confining pressure of shield tunnels，considering the influence of longitudinal deformation，is proposed. A simplified finite element model of shield tunnel segment rings is established for structural calculation and analysis. Taking a underlying shield tunnel of Hangzhou metro line 1 as an example，the calculated values of the horizontal convergence of the tunnel is compared with the measured data to verify the reliability of the calculation method. The confining pressure，the internal force of linings and the relationships of the longitudinal and transverse forces are studied，and the influence of the excavation size of the foundation pit is analyzed. The results prove that the calculated horizontal convergent deformation of the underlying tunnel and its distribution along the tunnel well match the measured values. The unloading effect of the confining pressure caused by excavation mainly affects the top and bottom of the tunnel lining and is affected by the forces between segments in the process of longitudinal deformation. The excavation causes the reverse of the bending moment on the shield tunnel lining and significantly reduces the axial force at the arch waist. The three-dimensional unloading ratio V3D can better reflect the influence of the size of the excavation on the underlying shield tunnel.

In order to evaluate the influence of horizontal freezing tunnel construction on the adjacent orthogonal subgrade more reasonably，considering the non-uniform frost heave of soil and regarding the subgrade structure as an elastic Euler Bernoulli continuous beam， a coupling calculation equation for evaluating the effect of horizontal freezing tunnel construction on the adjacent orthogonal subgrade was deduced based on deformation coordination conditions，random medium theory and superposition principle. The reliability of the random medium prediction method was verified by an engineering example，and the accuracy of the coupling method was shown by comparing the measured values with the calculation results of the coupling method and the two-stage method. Finally，numerical simulation was carried out based on ABAQUS software，and the results show that the coupling method and ABAQUS simulation results are in good agreement with each other. It is also shown that the uplift displacement at the same location of the subgrade increases gradually as the frozen wall expands，and that the lower the temperature of the refrigerant medium or the shallower the tunnel depth，the larger the uplift deformation of the subgrade. The frozen pipes in silty clay layers have the greatest impact on the uplift deformation of the subgrade. The improved calculation method in this paper can provide some theoretical guidance for the protection measures to reduce the influence of horizontal freezing tunnel construction on subgrade.