The cohesion and friction of rock do not act at the same location simultaneously, therefore，the linear Coulomb criterion does not describe the rock strength accurately. The friction within fissures is related to the confining pressure. A fissure will not slide as the friction approaches the cohesion of intact rock in its neighborhood. And thus，the range of dip angle of fissures affecting the strength of specimen decreases gradually with the increase of confining pressure. The linear variation of the strength under the low confining pressure is usually induced from the fissures with the specific dip angle，and is not applicable to calculate the internal friction coefficient in the Coulomb criterion. The natural fissures with various dip angles in sandstones result in the scattered uniaxial compressive strength under the low confining pressure. The strength varies regularly with the confining pressure，and their relationship can be described with the exponential criterion. The plastic deformation due to the axial compression results in the cohesion losing from low to high in marble specimens，while the thermal damage in marble causes the cohesion losing in full scale. Freezing enhances the cohesion but has no influence on the internal friction. The conventional triaxial strength of macroscopically isotropic rock is perfectly fitted with the exponential criterion，from which the initial influence coefficient of confining pressure on strength is applicable to estimate the friction coefficient of fissures.

TAW–2000 kN triaxial experiment system and SH–II AE signal acquisition system were used to investigate the energy conversion and acoustic emission characteristics of coal under uniaxial cyclic loading. The coal sample c05 suddenly burst when failed. The curve of c06 had a plastic jump before destruction. The local buckling of c08 was accumulated into interferential damage and the curve fluctuated and dropped suddenly when the sample failed. The instability precursor was analysed through the perspectives of energy conversion. Elastic energy reaching the peak value and the elastic energy index reaching the maximum through accelerated growth of the dissipated energy was the first judgment. In the second judgement，the elastic energy is constant，and the plasticity is increased. With the increase of cyclic loading，the dissipated energy presented an overall upward trend. The vibration resistance of coal samples evaluated according to the damping ratio was in the order of c06＞c08＞c05，which was consistent with the uniaxial compressive strength. The radial elastic energy and the volumetric elastic energy both showed a trend of decrease and the radial plastic energy and the volumetric plastic energy both tended to rise，which may be taken as the instability criterion. The peak count of acoustic emission in the loading stage presented a trapezoidal shape，and the peak count in the unloading stage showed a decreasing trend. The Kaiser effect of the cyclic loading is obvious，while the felicity effect in the later stage of cyclic loading is obvious. The variation of characteristic parameters of AE in the loading and unloading stage indicated that the plastic properties can be showed with the AE count in the loading stage and the energy and dissipation energy can be characterized with the AE count in the unloading stage. The accumulative count of AE and the plastic properties showed consistent regularity，the dissipation energy and AE energy showed consistent regularity. The sudden increase of AE energy and the sudden reduction of AE amplitude can be used to predict the breaking of coal and rock.

One of the main geologic disasters，the avalanche of perilous rock has important influence on the loss of lives and economic values. The indirect effects of water in fissures on the dynamic stability are not taken into account in Chinese specifications. Based on the assumptions of solid and fluid mechanics，the coefficient of reflection and transmission of the incident P waves at the interface of solid-liquid was deduced and verified in terms of the energy conservation，and then the hydrodynamic pressure acted on the perilous rock was calculated. The influence of the elastic modulus，density and Poisson?s ratio on the dynamic stability coefficient was studied qualitatively according to the expression of the transmission coefficient. The proposed method has been extensively applied to analyze the stability of unstable toppling rocks at Wanzhou district in Chongqing. The influence of the rainfall intensity and ground motion intensity on the stability of perilous toppling rock was discussed. The dynamic stability coefficient was reduced considering the hydrodynamic pressure in fissures. The reduction was more obvious in the case of rainstorm. It was concluded that the hydrodynamic pressure should be taken into account for the stability analysis of unstable rock in complicated surrounding conditions.

The weighted joint density(wJd) method was revisited and modified by considering the angle between the structural plane and the observation surface，which offered better information for characterizing the degree of joints in the rock mass. The accuracy of the method relies on the measurement of the angle between each joint and the observation surface，and in particular，for the inclined surfaces. A modified wJd method was derived for the inclined surfaces based on the original form of wJd method calculated from the geometrical relationship between the angels of pitch/dip and strike. The accuracy of the modified method was validated in practice and discussed in the paper. Validation was performed in light of the dataset obtained from three case studies to calculate and compare the values of wJd with different sampling methods，including the global grid method，the overlying gird method，and the elementary unit method. The results were compared with the corresponding values obtained using the volumetric joint count(Jv) method，and the elementary unit method(1 m×1 m) yielded the most optimal outcome and reduced the bias induced by the offset of traces. The results demonstrate that the modified wJd method provides a novel and reliable means of evaluating rock mass quality for inclined surfaces.

Experimental study on the ejection process of strain rockburst in coarse-grain granite using the rigid true-triaxial test machine for rockburst developed in house was presented. The processes of ejecting failure in focused energy driven rockburst and in concentrated stress driven rockburst were respectively simulated with different loading and unloading paths. The speed of rock fragments was recorded with the high speed camera system and the characteristics of rockburst were analyzed. Rockburst was found to have four typical stages such as small grain ejections，spalling，shearing rock into fragments and fragments ejection. The failure of the specimen after rockburst had a V-shaped notch or sidestep-shaped notch near the free face and a shear zone away from the free face. Loading rate had important influence on the concentrated stress driven rockburst. The kinetic energy had an increasing trend with the increasing of loading rate ranging from 0.05 MPa/s to 2 MPa/s. Gathering enough elastic strain energy and inputting energy with enough high rate in the pre-peak are essential conditions for stress concentration driven rockbust. Whether it is the focused energy driven rockburst or the concentrated stress driven rockburst，less than 1% of released elastic strain energy in the pre-peak was translated into the kinetic energy.

Seasonal temperature variation induces cyclic frost heaving and shrinkage of rock in cold regions. The unfrozen water content and frost heave in rock under low temperature are the key problems for numerical simulation and stability analysis of engineering in cold regions. Because rock，different from soil，is a brittle porous medium，its unfrozen water content cannot be directly measured experimentally. Considering the existence of unfrozen water films and the freezing point depression of pore water at low temperature，a theoretical expression of unfrozen water content in frozen rock was established with the assumed distribution function of accumulative pore volume，and the expression was validated to be reliable with examples. Assumed rock as the elastic porous medium，the ice pressure was derived on the condition of volume equality. The ice pressure in pores was considered to be equivalent to the triaxial tensile loads on the surface of rock and a frost heave model was thus established based on the elastic theory. The results show that the frost heaving strain in saturated frozen rock is a function of the mechanical parameters of rock matrix，porosity and unfrozen water content. Finally，the frost heave model was validated to be correct and practical by comparison with two existing frost heave experiments.

To date，some criteria have been proposed to estimate the peak shear strength of rock discontinuities. Although these criteria contribute to the understanding of the shear behaviour of rock joints，there are still some limitations that should be recognized. For example，these criteria cannot describe the anisotropic properties of rock discontinuities. Considering both asperity inclination angle and amplitude，a new parameter ? describing the discontinuity roughness is proposed in order to comprehensively predict the peak shear strength of rock discontinuities，which can be expressed by the anisotropic parameter SRv and amplitude parameter A. The anisotropic parameter SRv is obtained with the Variogram method. The relationship between JRC and ? is established through calculating ten standard roughness profiles and a shear strength model accounting for anisotropy was developed based on Barton?s peak shear strength criterion. The morphology of artificial rock discontinuities was measured with ShapeMetriX3D system，the parameter ? was calculated and the peak shear strength of the studied surface was estimated by the proposed method. Meanwhile，the shear tests on the artificial rock discontinuities were carried out. The new model of peak shear strength was validated with the results from shear tests.

The propagation process of stress wave across the macro interfaces with larger thickness is difficult to be described using the linear elastic model of discontinuous displacement. The linear elastic model of discontinuous displacement was improved by adopting the multistage Taylor expansion of displacement component and stress component on the side of interface transmission. The elastic modulus of the interface was calculated using the customary and improved models respectively. The effect of impedance ratio and interface thickness on the test error was analyzed. The elastic modulus of the interface should be measured using the customary model based on the waveform difference of transmission wave when the impedance ratio was larger. The effect of interface thickness on the test deviation was analyzed using the vibration waveform of measuring points through numerical calculation. The test deviation，based on the reflection waveform difference adopting the improved model，decreased with the increase of the interface thickness. However，the test deviation based on the transmission waveform difference adopting the customary model increased with the increase of the interface thickness. The results of the field test and the numerical simulation were consistent with each other.

To deal with the problems associated with anchor rope support in tunnels with slow and instantaneous large deformation which occurred frequently in coal mines，an appropriate high constant resistance and large deformation anchor rope，which is made of the constant resistance device and anchor body，has been invented based on the oretical analysis，laboratory and field tests. The laboratory test showed that the constant resistance anchor rope provided a constant resistance of 350 kN and the displacement reached 300–950 mm under the static tension，and that the burst resisting force was 280–375 kN under the burst impact dynamic load when the limit elongation was not exceeding 1.6 m. the developed anchor rope displayed the detachment failure instead of breaking failure of traditional anchor rope. Once the anchor rope force exceeded the maximum constant value，the constant resistant cell began to slip. In the slipping stage，the temperature of the constant resistant cell increased rapidly first，then decreased slowly and approached stable finally. The highest working temperature is 35.6°. The external conjugate diameter of the constant resistant cellswasenlarged evenly along its axis，exhibiting a negative Poisson?s ratio. The maximum value of radial expansion is 4.1 mm and the Poisson’s ratio is between －0.5 and －2.0. In the blast impact failure test at backstopping tunnel，the high gas and constant resistance anchor rope entry retaining and the large section cut roof entry retaining，the maximum slipping value of constant resistant cell was 57 mm. The constant anchor rope has the advantage of low temperature，high pretightening force，and large elongation.

Characteristics of fracture evolution inner loaded rock are significant for understanding rock failure mechanism. In this paper，acoustic emission(AE) and CT imaging techniques were combined to perform CT inversing calculation for mudstone samples in different loading speeds， the characteristics of velocity distribution in rocks in different loading phases were analyzed，and relations between velocity evolution and macro- and micro-fractures of rocks were studied. The results show that：(1) In initial loading phase，the variation of velocity scale in rock samples is minor，and the velocity anomalies regions are small and distributed scatteredly. When loading increases，the velocity scale grows and the velocity anomalies regions are enlarging continuously. Before failure，the velocity scale further increases and large areas of low velocity regions connect mutually. (2) The macrofractures position in rock samples after failure has a positive corresponding relation with the region of low wave velocity and affluent wave velocity anomalies，indicating that when approaching failure，numbers of sprouting and growing microfractures lead to rapid expansion and connection of low velocity regions，and the regions of particles around microfractures represent high velocity status caused by compression；(3) In initial loading phases，locations of the emerging micro-fractures correlate well with low velocity regions. When loading increases，numbers of microfractures sprout in the regions of low velocities and affluent velocity anomalies. Before failure，dense areas of microfractures expand and connect，which correspond with the macrofracutres of rock samples. (4) There is a similar AE events distribution before and after inversing calculation，which proves the accuracy of the initial AE locations and the reliability of CT imaging results.

Leakge is a big problem for the safety and efficiency of drilling. The fracture aperture，circumferential stress and stress intensity factor of fracture tip were studied in the case of bridging or sealing in different fracture locations with the numerical method. The results show that，when the wellbore pressure is constant，the longer the fracture，the larger the stress intensity factor and the fracture aperture. The bridging location in the fracture opening has the best effect，with the circumferential effective stress enhanced the most and the stress intensity factor the lowest. The lower the fracture pressure，the more enhanced the circumferential effective stress and the smaller the stress intensity factor. Suitable particle size should be chosen in accordance with the fracture aperture while drilling. Sealing micro-fractures quickly and efficiently by constantly adding LCMs and using high-performance LCMs can prevent the occurrence of pernicious mud loss effectively，and improve the pressure bearing capacity of the formation.

The self-anchored strengthening structure was put forward to solve the reinforcement issue of tunnels located in the deep landslide，in this paper，stress and deformation of the entire reinforcing structure under the interaction of landslide soil were studied. A physical and mechanical calculation model was established and the matrix transfer method was adopted to establish the calculation formulas of internal force and deformation. The internal force and displacement distribution characteristics of the reinforced structure were obtained by MTLAB programming calculation. Numerical simulation calculation and model test were carried out to verify the theoretical results. The results indicate that：(1) The anti-slide sustaining pile and anchor can control the displacement of the tunnel well and improve the stress state of the tunnel；(2) In the design， the angle between the anchor cable and horizontal plane should be minimized，and the design anchor force values in the scope of the landslide boundary should be increased；(3) The internal force and deformation results of numerical simulation calculation and physical model test are in good agreement with the theoretical calculation results，which verify the correctness of the theoretical calculation method.

The residual coal mining face #3101 at Shenghua Coal Industry of Jincheng Anthracite Mining Group was studied to investigate the roof fracture characteristics，surrounding rock stress distribution and support stress state in the caving zone for residual coal mining face using the analog simulation considering the coal face sloughing，tip-to-face flaking and larger roof weighting strength features. On the basis of the simulation results，a mechanical model of residual coal mining field was established，a formula calculating the hydraulic support strength was derived，and further surrounding rock control technology in the caving zone for residual coal mining face was proposed. The roof of residual coal mining field was found to form easily thicker and long-span advanced fractures. The caving zone weakened the stress transfer of roof strata and aggravated the loading intensity of the support pressure. The working resistance of the hydraulic support suddenly increased due to the effect of advanced large fracture，its maximum value from numerical simulation is 16 200 kN，and the theoretically calculated value is 16 110.5 kN. The residual coal mining face must be grouted before passing through the caving zone. The relationship between the support working resistance and filling body strength was determined.

A high-precision microseismic(MS) monitoring system was installed to evaluate the stability of the left bank bedding slope at Baihetan during excavation. The main damage regions of the left bank slope were delineated through real-time monitoring and analyzing of the MS activities. The initiation，propagation，extension and coalescence mechanisms of mircocracks were revealed using the realistic failure process analysis(RFPA) approach. The full progressive failure processes of the rock slope at atypical section were reproduced. The MS activities were found to match well with the excavation disturbances. The MS events induced by the slope excavation were mainly distributed around the dam spandrel，especially along the internal staggered zones LS331，LS337 and the hanging wall of fault F17(610–700 m)，forming the main damage regions of the slope. Influenced by the excavation-induced unloading of the slope，the stress concentration was highlighted in the weak structures such as LS331，LS337 and F17，and myriads of rock failure elements continuously propagated in these regions，resulting in the rock failure along the weak structures. Numerical simulation results coincided with the trend of spatial macro evolution of MS activities.

A pseudo threshold pressure gradient was introduced into the Biot equation to study the low-frequency vibration stimulation in low permeability reservoir. The solution of the governing equation from Laplace transform and Durbin discrete method verified that the low-frequency vibration stimulation resulted in seepage enhancement and pressure increase. Laplace transform with respect to the time，the iterative elimination and the order lowering of non-homogeneous differential equation were employed to solve the governing equation. Numerical analysis based on the expressions and fitting properties of rock from Yanchang field was carried out with the Matlab programming. Examples with the porous media saturated with water phase，or with oil phase under different vibration frequency were given to analyze the change in seepage rate，pressure，porosity，solid strain and swelling shrinking ratio of the fluid. The results showed that the seepage velocity and porosity were increased obviously in the injection side by the low-frequency vibration stimulation. There existed an optimum vibration frequency in the range of 10 to 30 Hz to reach the biggest increase in porosity and permeability，which agreed with experiment results.

In tunnel construction，sprayed concrete as a necessary means of primary support plays an important role on the stability of tunnel surrounding rock control，and the quality and dosage of accelerator directly affect the shotcrete strength and the construction environment. Based on the accelerating mechanism of aluminate accelerator，a new high performance and low dosage of liquid accelerator is developed，The accelerator has good properties. for examples，the caustic ratio is less than 1.2，pH value is 9–1，the amount of solid is 65% and the solution is stable without precipitation. Through the analysis of the XRD and SEM and the related performance tests，the accelerator can effectively improve the degree of hydration of cement，and in a short time，form a large number of calcium silicate，which overlap each other to form crystal structure，and hence reduces the setting time. The  suitable dosage of the liquid accelerator is 1.5%–3% of cement quality，while the sprayed concrete late strength loss within 10%. In the field application，a high precision and small flow rate of liquid accelerator adding device is developed to ensure the precise control of the dosage of liquid accelerator. The corresponding matching spraying technology was improved，which can effectively improve the shotcrete strength，reduce the dust and rebound in the construction，and therefore have good popularization and application value.

To enhance the reliability and effectiveness in design of laterally loaded single pile，a link finite element method based on the principle of composite stiffness and bi-parameter was presented. Some flaws in the m-method recommended by the current technical codes for the design of laterally loaded pile were pin pointed through theoretical analyse and static loading experiments，and a modified method was proposed. Unlike the analytical approach，the is link finite element method established in this paper has no restrictions in parameter selection and avoids tedious calculations of table looking-up. In addition，it is not necessary to assume the restraint conditions of piles tips and discriminate the long，short or medium piles. Comparisons with the practical examples showed that the results between the link finite element method and analytical approach agreed well when the same composite stiffnesses and bi-parameters were employed. The calculated displacements and rotation angles at the tops of the piles and the maximum bending moments and their positions were in agreement with the measurement. Comparisons also showed that better results than those of the analytical approach was achieved through multiple trial calculating and adjusting of the exponent n and composite stiffness EI when the values of the proportional coefficient m were determined according to various layers of soil around the piles.

The unsaturated soil seepage occurs widely in the dam seepage，rainfall infiltration and pollutants diffusion in landfill etc. The numerical solution of unsaturated seepage equation of Richards based on the finite element algorithm has been derived with the matrix suction head as the independent variable. However，the strong nonlinear characteristics of the material properties leads to the poor mass conservation properties and non physical oscillation of the numerical solution，and may cause inconvergence of the iterative process at the same time. In order to obtain a numerical solution with mass conservation，smoothed particle method was introduced into the solution of the head-based form of Richards equation，and the practicability and reliability of the new algorithm was verified by a numerical example. Finally，a complex unsaturated seepage problem with the evaporation condition was simulated using a program which was written based on SPH algorithm.

In order to carry out the all-round prediction with high efficiency and high precision for the metro train-induced environmental vibration，the effect of the actual moving award process of train on the environment was taken into full consideration，and the tunnel-soil system was supposed as a longitudinal periodic structure，which consists of a series of the identical sliced structures successively arrayed in the longitudinal direction of tunnel. Each sliced structure was supposed to be composed of the finite elements in the near field of tunnel and the infinite elements in the far field away from the tunnel which can provide good boundary conditions. Based on the decompositions of the environmental vibration excitation forces into the components corresponding to the wheel-rail forces with various excitation frequencies，utilizing the principle of superposition and the periodic boundary conditions existed in each longitudinal sliced structure under the wheel-rail forces with a single excitation frequency，the solution of the vibration response of the actual three-dimensional tunnel-soil system induced by the moving train was transformed to be solved within a longitudinal sliced range in the frequency domain. Computation results show that the proposed model can effectively predict any train-induced vibration physical quantity of tunnel-soil system in any direction. the model not only has high prediction precision，but also has fast calculation speed and strong calculation ability. The ground surface vibration velocity and acceleration responses in the transverse，vertical and longitudinal directions induced by metro train have the similar frequency components，and their time-domain maximum amplitudes are in the same order of magnitude.

To explore the influential factors，regular patterns and mechanism of adfreezing strength on the interface between artificial frozen sand and structure，an experimental study was conducted with the large-scale direct shear apparatus developed in-house. All the adfreezing strengths were found to be affected notably by many factors， such as freezing temperature，normal stress and roughness，etc. The adfreezing strengths increased with decreasing temperature. The ultimate adfreezing strength presented a linear relation with the temperature，and the residual adfreezing strength varied with the temperature and presented three typical regular patterns. The adfreezing strengths increased with increasing the normal stress. The relation between the ultimate adfreezing strength and the normal stress was in line with Mohr-Coulomb criterion，and the residual adfreezing strength varied with the normal stress and also presented the same three typical regular patterns. The adfreezing strengths increased with increasing the roughness. The relation between the ultimate adfreezing strength and the roughness satisfied a logarithmic function. The fluctuation cycle about the residual adfreezing strength curves increased with increasing the roughness. In addition，the internal mechanism of adfreezing strength was revealed. The stick slip phenomenon in the residue adfreezing strength was also explained. Through the regression analysis of multiple factors affecting the adfreezing strength，an empirical formula for the adfreezing strength related to the temperatures，normal stress，and roughness was derived.

The shape of the rock block influence greatly the meso-structure and macro-meso mechanical behaviour of soil-rock mixture(S-RM). In this paper，a method for the study of meso-mechanics of S-RM based on the real shape of rock blocks was presented. Firstly，the database of 3D geometric model of rock blocks was built based on 3D scanning technology. Then，with the database and the block size distribution，a special 3D model of S-RM with rock blocks was generated. A numerical model of S-RM sample was also generated. Furthermore，using the proposed multi-sphere modelling method of complex blocks，arbitrary particles can be modelled with the multi-spheres contacted uniformly and closely. As a result，a 3D DEM meso-structural model of S-RM sample was generated. In accordance with the field test，a series of 3D numerical direct shear tests were carried out. The meso-mechanical parameters of the soil particles used in the DEM numerical test were obtained from the field tests. The results of numerical tests indicated that the rock blocks made the shear zone of the S-RM sample wider and more zigzag than that of the soil sample，which induced the higher friction angle of the former. However， with the increase of the rock block content，the content of the fine soil particles with binding function decreased. As a result，the cohesion of S-RM was smaller than that of the soil sample.