In order to solve the problems of the waste of coal pillars and the limitation of working faces，the rapid gob-side entry retaining technology by roof cutting and pressure releasing was introduced into the 8304 working face of Tashan coal mine. The technological process and the space-time relationship of the new gob-side entry retaining technology were summarized，based on which the surrounding rock structure was divided into coal support zone，dynamic pressure zone and lane stable zone. Taking 8304 working face as an example with composite roof and medium thick coal seam，the relevant parameters of six key technologies including roof cutting，shaped blasting，constant resistance anchor cable support，retaining support，temporary support and loose blasting were respectively designed. The technical effects of related designs were verified by numerical simulation and field test. The practice results show that the ultimate convergence of the roof and the bottom of the roadway is 261 mm，the shrinkage of the two sides of the roadway is 390 mm，the effective section size of the roadway is 2 839 mm×4 610 mm，and the remained roadway is sufficient to meet the reuse requirement of adjacent working faces.

The purpose of this paper is to investigate the equivalent ground shock effects of hypervelocity impact and shallow buried explosion in rock. Based on the similarity of craters resulted from hypervelocity impacts and shallow buried explosions，the crater can be regarded as the source of ground shock effects，and the equivalent relationship between hypervelocity impact and shallow buried explosion can be established assuming that ground shock energies of them are equal. The relationship between the equivalent charge and the dimensionless impact velocity was obtained，and a simplified expression of the energy conversion coefficient was given. Experimental results of hypervelocity impact on granite indicates that the ground shock waves of equivalent charge explosion and hypervelocity impact are highly similar，which verifies the validity of the equivalent method in the case of a large enough dimensionless impact velocity. When the dimensionless impact velocity increases，both the equivalent charge and the energy conversion coefficient increase. Based on the equivalent method，the relationship curves between the safe thickness of protective layer and the mass of projectile were obtained with the impact velocity of 5 Mach，10 Mach and 15 Mach respectively.

To investigate the cumulative damage characteristics of rock joints under different failure modes，the original rock samples with second-order asperities were obtained by adopting water knife cutting processing method，and the direct shear test was carried out under pre-peak cyclic loading conditions. The influence of the cyclic loading times，the loading rate and the loading amplitude on shear properties of rock joints were analyzed. Results show that the cumulative damage of a rock joint with climbing failure mode is characterized by the abrasion of second-order asperities，that the cumulative damage of a rock joint with cutting failure mode is characterized by the crack initiation and crack coalescence of the first-order asperity，and that，under the climbing-cutting failure mode，the cumulative damage of a rock joint has the damage features of the climbing failure and the cutting failure modes. With increasing loading cycles，the peak shear strength of the rock joint presents a trend of increasing at first and decreasing subsequently while the residual shear strength of the rock joint almost keeps stable. When the loading rate or the loading amplitude increases，the deterioration speed of the peak shear strength of the rock joint increases and hence，the peak shear strength of the rock joint decreases. The effect of pre-peak cyclic loading on the rock joint can be attributed to contact effect and damage effect，and the evolution of the two effects is the root cause for the peak shear strength of the rock joint increasing at first and decreasing subsequently during direct shear test under pre-peak cyclic loading.

In order to analyze the energy evolution and permeability characteristics of coal during the coal mining process，the triaxial cyclic loading and unloading tests were carried out by controlling the confining and axial pressures，and the permeability was measured. The evolution characteristics of elastic parameters(elastic modulus and Poisson?s ratio) and energy densities with the axial strain were analyzed under different confining pressures. A modified damage variable was introduced for this elastoplastic material and its correlation with the permeability was explored. The results show that，during the loading and unloading processes and after entering the yield phase，the elastic modulus begins to decrease，and the dissipated energy density，dissipated energy ratio and damage variable gradually increase，and that in the post-peak period，changes of these parameters develop rapidly. It is also demonstrated that rock damage is an energy-dissipating damage evolution process. Taking the yield point as the demarcation point，the relationship between the permeability and the damage variable can be described by a logarithmical function and an exponent function before and after yielding，respectively，and the fitting formulas were obtained under different confining pressures. The permeability decreases with increasing the confining pressure，which indicates that the confining pressure has an inhibitory effect on permeation.

A polymeric seal is the critical structure for high-pressure air storage in lined rock caverns(LRCs) for compressed air energy storage(CAES). However，the air tightness and mechanical characteristics of polymeric seals under operational conditions are still unclear. Some problems，such as whether air leakage occurs and how much high pressure air permeates，are unsolved. In this paper，the permeabilities of four types of polymer(IIR，EPDM，NR，FRP) were measured by a self-developed equipment for high pressure gas test，and mechanical parameters of the polymers were also measured. The governing equations of the multi-physical coupling process in CAES caverns were proposed and validated by the in-situ test data of Huntorf plant and a Japan pilot cavern. The air tightness and mechanical characteristics of polymeric seals under operational conditions were calculated and analyzed using the experimental data and governing equations. Results show that a certain degree of air leakage occurs through three types of polymeric seals(IIR，EPDM，NR) except FRP. Nevertheless，all polymeric seals(IIR，EPDM，NR，FRP) meet the requirements in terms of air tightness and mechanical stability. Among these four type polymers，IIR and FRP are preferred materials for internal seals in LRCs. It is also indicate that the proposed governing equations are capable of effectively obtaining accurate responses of LRCs for CAES.

In order to get more reasonable corresponding stress value( ) in Kaiser effect points of different sedimentary rocks，the uniaxial cyclic loading tests were conducted，combined with acoustic emission technology. The influence of the loading cycle peak stress( )，the loading rate and the moisture content on Kaiser effect for rocks was discussed，and a reasonable multi-cyclic loading model was proposed. The results indicate that，as the loading rate or the water content increases，both the ringing count and the energy of fine sandstone decrease but Felicity ratio(FR) changes insignificantly，and that the impact of the loading cycle peak stress on sand Kaiser effect is more significant than the loading rate and the water content，and when is greater than the previous maximum stress( )，the damage memory of rock will be further deteriorated which results in that FR changes more significantly. It is also shown from cyclic loading KE tests that the reasonable values of first circulation of various sedimentary rocks such as siltstone，fine sandstone，medium sandstone，coarse sandstone，sandy mudstone，mudstone and limestone are respectively less than 25.65%，21.66%，12.31%，11.31%，23.40%，3.61% and 4.32% of the corresponding uniaxial compressive strengths( )，and other cyclic does not exceed 59.39% to 75.72% of  . Stepwise regression analysis of   reveals that the elastic modulus，the buried depth and  can enter the regression equation with a fitting degree of 0.556.  is a linear function of the buried depth with a correlation coefficient of  0.592. The research results provide a theoretical basis and reference for measuring the in-situ stress by Kaiser effect.

To address the indeterminacy of contacts involving nonconvex angles of arbitrarily shaped polyhedron，an easy-to-implement local convex decomposition method(LCD)，dividing any arbitrary angle along the extensive plane angle of concave dihedral angles into a set of convex angles，was proposed and employed to extend the entrance plane method(EPM). The LCD-EPM is a universal method for contact detection of general polyhedrons，and herein，enabled the use of a three-dimensional discontinuous deformation analysis (3-D DDA) to calculate contacts between general polyhedrons. Finally，the extended 3-D DDA program was used to illustrate the powerful ability of LCD including contact detection and calculation as well as an impact-contact behaviour analysis of general polyhedrons，which validates the correctness and robustness of the LCD-EPM. The extended 3-D DDA program can be applied in mechanical analyse of complex polyhedral block systems.

Taking a typical loess-mudstone landslide in Tianshui city of Gansu Province as a prototype，using the conceptual model of the loess-mudstone slope with an 80°dip angle bedding fault zone and inputting different seismic waves with different peak accelerations，the shaking table test with a size similarity of 1∶20 was designed and completed. Based on the shaking table test and numerical simulation，the seismic dynamic responses and failure modes of loess-mudstone slopes with a steep dip bedding fault zone were revealed. The results show that the dynamic response of acceleration reflects an obvious surface effect and the amplification effect at the fault zone is greater than that of both side strata of the fault zone. The peak acceleration a = 0.3 g is the critical point of seismic responses of slopes，and the acceleration amplification effect at the hanging wall，the vertical and horizontal earth pressure responses are different while the peak acceleration is less or greater than 0.3 g. When the peak acceleration is less than or equal to 0.3 g，the amplification effect at the hanging wall is not obvious，the vertical earth pressure response is positively correlated with the thickness of the overburden strata，and the horizontal earth pressure response is strongest at the slope shoulder and has a decrease trend at fault zone. When the peak acceleration is greater than 0.3 g，the amplification effect at the hanging wall is very obvious，the vertical earth pressure response is controlled by both the fault zone and the thickness of the overburden strata，and the horizontal earth pressure response is strongest at the slope foot. The failure of loess-mud slopes with a steep dip bedding fault zone under the action of seismic waves is a shock slip failure mode and the width of the fracture distribution area in the loess-mud slope induced by seismic waves on the hanging wall is 1.5 times that of the footwall of the fault zone，which indicates that the slope with a steep dip fault zone has a certain amplification effect on the hanging wall of the fault zone.

To study the initiation mechanism of strain rockbursts，model tests on strain rockbursts induced by unloading in deep underground opening were conducted based on elastic adaptive boundary. The phenomena of strain rockbursts were reproduced in the laboratory. At the distances of 2 cm and 8 cm from the tunnel wall，the hoop pressure values of the surrounding rock increase by 63.3% and 42.9% respectively，and the radial pressure values decrease by 79.2% and 29.3% respectively. The maximum values of the radial and hoop strains，2 cm away from the tunnel wall，reach －2 443  and 1 268  respectively. The convergences at the vertical，left and right sides of the wall in the tunnel after excavation are respectively 0.37 mm，0.53 mm and 0.55 mm. In the process，brittle failure phenomena of the surrounding rock including block-fracture and strain rockburst were observed，and the failure of the surrounding rock displayed an obvious lag effect. The mechanism of strain rockbursts was established. The test method can simulate strain rockburst phenomenon well，and the study conclusions can provide a reference for further theoretical study and engineering practice of rockbursts.

In shear tests of rock joints，constant normal load(CNL)，constant normal displacement and constant normal stiffness(CNS) conditions are used. Compared to the first two conditions，Shear stress-displacement curves display more complicated in the case of CNS condition. Aiming to evaluate shear behavior of rock joints under CNS，an extension was made to model strength softening and strength hardening processes in a unified form on the basis of the approach which takes strain softening process as a series of stress drop and plastic flow，and the corresponding formulation was presented. Shear behavior was modeled under various CNS conditions. The results show that shear stress-displacement curve displays in strength softening mode when the normal stiffness is small but that strength hardening mode appears while the normal stiffness increases. The shear stress-shear displacement curves，normal displacement-shear displacement curves and normal stress-shear displacement curves were compared with test results and good agreements between them were observed，which indicates that the presented procedure is reliable. Furthermore，the shear behavior of rock joints was studied under different combinations of the initial normal stress and the normal stiffness.

During blasting excavation of deep tunnels，the rapid in-situ stress release occurring on blast-created free surfaces is one of the major dynamic disturbances. For a deep circular tunnel which is excavated with the full-face millisecond-delay blasting method，the mechanism and influence factors of rock vibration induced by the transient unloading was analyzed，and vibration control methods were discussed in detail from the perspectives of cutting modes，blasthole arrangements and initiation sequences. The results show that properly designing drilling and blasting parameters can reduce initial stress levels on the excavation surfaces，prolong the duration of the transient unloading and reduce sizes of the excavation surfaces，and that，as a result，rock vibration induced by the transient unloading can be effectively controlled. The research work can be applied to blasting construction of deep tunnels in the industries of deep resource exploitation and deep space utilization.

For soft rocks，point load test is often used as an effective method to evaluate the strength quickly and easily due to that it is difficult to obtain complete cylindrical standard specimens. Based on the mechanical essence of the point load strength，the difference between the calculation models of load spacing method and equivalent diameter method was analyzed. By introducing the width ratio of the actual breaking section to the minimum section，the unified expression of the equivalent area method with taking the minimum section area as the basic parameter was constructed. The samples of irregular soft phyllite were adopted to discuss the variation characteristics of the ratio with different weathering degrees and to investigate the influence of the shape factor and the loading point space on the point strength index. Test results show that the distribution of the ratio is highly skewed，and that，with increasing the weathering degree，the characteristic value increases slightly between 1.40 and 1.46，which is not only larger than 0.3–1.0 of the“load spacing method” but also greater than 4/π of the“equivalent diameter method”. Consequently，1.43 is suggested as the characteristic value for soft phyllite. The point load strength decreases with increasing the shape factor or the loading point space. With increasing the weathering degree，the sensitivity of the influence of the shape factor on the point load strength reduces gradually. While the relative deviation of the point load strength is less than 40%，for strongly，weak and slightly weathered samples，the shape factors are not less than 0.4，0.5 and 0.6 respectively and the loading point spaces are 35–80 mm.

以黄河上游某水电站层状岩体斜坡为对象，通过90个勘探平硐和地表大量变质砂岩和板岩层厚的现场测量和统计，揭示层厚的空间变化规律，分析岩层薄化的影响因素及影响范围，并基于地应力测量、岩体波速测试、三轴应力–弹性波耦合试验和数值计算，探讨卸荷作用下陡倾层状岩体斜坡的岩层薄化机制。结果表明：岩层薄化是岩性、构造、卸荷和风化等因素综合作用的结果，软硬相间岩层及其潜在弱面是岩层薄化的基础，构造作用使潜在弱面剪切，卸荷作用使潜在弱面显性张裂，风化使地表岩层进一步变薄，其中卸荷作用是主要和全局性的。河流下切使软硬相间陡立层状岩体斜坡内的地应力场非常复杂，坡顶和坡面岩层内潜在弱面直接拉张，斜坡内一定深度范围内岩层沿潜在弱面发生压致拉裂，斜坡内陡立层状岩体发生大范围岩层薄化。受之影响，层状岩体斜坡内层厚总体上随深度增加振荡式增加并在一定深度达到原生厚度而趋于稳定，层间错动带、褶皱带、卸荷裂隙带附近的层厚普遍较薄并也随埋深增大而增加，岩层厚度及影响范围随高程增加而增加，左岸反倾岩层的厚度和影响范围大于右岸顺倾岩层。层厚、埋深、纵波速度和应力状态之间具有较好的相关性，表明层状岩体的单层厚度始终受地应力场控制。研究成果为层状岩体力学性质与变形破坏研究以及工程设计提供基础。

In order to study fracturing and fractal characteristics of rocks containing a hole and multi-flaws，model specimens containing a hole and multi-flaws were prepared and uniaxial compression tests were conducted. Failure process of rock specimens was numerically studied by RFPA2D. Formation mechanism of tensile cracks and the effect of different flaw inclinations on the compression strength were explained by constructing an overhanging beam and structural plane mechanical model. Box-counting dimension method was introduced to quantify new cracks geometric distribution of physical and numerical model specimens after failure，and its correlation with fracture characteristics was investigated. Satisfactory agreement between numerical and test results indicate that the failure modes in the specimen can be classified into two modes，namely cutting through the flaw(mode I) and sliding along the flaw(mode II). The rock bridge near the pre-hole is considered as an overhanging beam model，and the generation of tensile cracks around the hole appears to be produced by the maximum bending moment acting at the non-symmetrical part of the overhanging beam. The compression strength of the specimens is weakened by pre-flaws，which can be explained by the structural plane mechanical model. With increasing the flaw inclination，the compression strength of the specimens decreases first and then increases，while the weakening factor shows a crosscurrent. The fractal dimension of new cracks geometric distribution of rock samples after failure is closely related to fracture characteristics. Compared with mode II，the specimen failing in mode I has a greater compression strength，leading to a higher fractal dimension. The results of data fitting show a positive correlation between the compression strength and the fractal dimension.

A high order dilatancy equation for considering the effect of the temperature on the dilatancy behaviors of clays is presented in the framework of critical state mechanics. Two material parameters related to the temperature are introduced in the dilatancy equation. Integrating the high order dilatancy equation will lead to a new yield function which is flexible to represent the experimental data of clays，and yield functions of the original and modified cam clay models can be regarded as the special cases of the new yield surface. Considering the influence of the temperature on the pre-consolidation pressure of clays，a new yield surface was obtained. Comparisons between the prediction results and the experimental datum were performed，and a good agreement between them was observed. It is shown that increasing temperature will lead to the yield surface of clays shrinking and，at the same time，the plastic dilatancy factor will decrease gradually. The proposed high order dilatancy equation and the yield surface related to the temperature can show an insight into the thermodynamic behavior of clays.

In order to fully understand the strength deterioration law of compacted loess caused by wetting-drying cycles，a series of triaxial tests considering the influence of the dry density，the wetting-drying amplitude and the lower bound water content of drying-wetting cycles were carried out，and the strength deterioration curves of compacted loess under different influencing factors were obtained. The effects of the dry density，the wetting-drying amplitude and the lower bound water content on the strength deterioration law were quantitatively analyzed by fitting a hyperbolic function to the deterioration data and as a result，a compacted loess deterioration model(CLDM) was established. Besides，SEM tests were carried out to study the microstructure change caused by wetting-drying cycles. A Python-based secondary development of finite element software was carried out in order to apply CLDM to ABAUQS，by which the stability of a loess fill slope after exposure to drying-wetting cycles was analyzed，and the applicability of the CLDM model was validated. Research results provide a theoretical basis for the analysis of the strength deterioration of compacted loess caused by wetting-drying cycles and for the prediction of fill slope disasters.

In order to provide a guide for design and construction of clayey soil subgrades in the Yellow River Alluvial Plain，the physical and mechanical properties of the medium-high liquid limit clay subgrade including the shear strength，the equilibrium moisture content and the long-term stability were studied. Direct shear tests under 24 conditions were performed. The relationships between the shear strength indices and compaction conditions were discussed，and the empirical formulae of the soil cohesion and the friction angle were established as functions of the moisture content and the compaction degree. Based on the 84 groups filter tests，the relationships between the saturation degree and the matric suction were obtained at different initial compaction states，and the empirical parameters of the soil-water characteristic curve equations were given according to MEPDG method and Frendlund & Xing model. The equations of the equilibrium moisture content and the corresponding shear strength of the medium-high liquid limit clay subgrade were deduced，and the critical subgrade height was proposed considering the safety factor and the equilibrium moisture content. Results show that，for the medium-high liquid limit clay mainly composed of silt particle with higher roundness in the Yellow River flooded areas，the shear strength indices is markedly influenced by the soil moisture content but that the friction angle is independent on the compaction degree. The high soil air-entry value(more than 199 kPa)，ascending with increasing the compaction degree，indicates that the soil with a high compaction degree has great water retaining capacity at high saturation state. The equilibrium moisture content is bigger by 4%–8% than the optimum moisture content，which results in a larger reduction of the shear strength. For the typical bi directional and four lane highway in the Yellow River flooded areas，the critical subgrade heights at the construction and equilibrium moisture contents are 20 m and 8 m respectively.

Based on the assumptions of one-dimensional nonlinear consolidation proposed by Davis and Raymond，one-dimensional nonlinear consolidation of soils under instant loading was investigated by introducing the continuous drainage boundary. An analytical solution of the one-dimensional nonlinear consolidation problem of soils was derived by utilizing variable substitution，variable separation and Laplace transform，and the reasonableness of the solution was verified compared with Davis solution. Influence of different interface parameters or nonlinear parameters on consolidation behavior of soils was analyzed in detail. The results show that the boundary conditions of the presented solution can strictly meet the initial conditions，and that the consolidation equation is well-posed and its solution is continuous. The average consolidation degree，Us，defined by the settlement，increases with increasing the nonlinear parameter  ，but the average consolidation degree，Up，defined by the pore pressure， decreases with ascending  . Comparisons indicate that the interface parameters have more marked influence on soil consolidation than the nonlinear parameter .

In the numerical simulation of the thermal-force coupling of permafrost soils，the frost expansion coefficient is the key thermal physical parameter. At present，the negative thermal expansion coefficient is taken by most scholars as the frost expansion coefficient，and only the change of the temperature is considered. However，the frost expansion coefficient is actually affected by many factors. Based on the theory of elastic mechanics and without considering the frost heave caused by water migration，the relationship between the frost heave rate and the frost heave coefficient of soil body during freezing process caused by in-situ water freezing was studied. Taking into account the factors such as the temperature，the poisson ratio of soil body and the phase change rate of ice water under freezing state of different soil materials，a formula between the frost heave rate and the frost heave coefficient was derived. Comparisons between the developed method and the traditional calculation method were performed based on the basic physical parameters of soil mass measured in Qingshuihe area of Qinghai—Tibetan Plateau. As is shown by the results，the method considering multiple factors has smaller errors and can be used to accurately simulate the frost heaving process caused by water freezing in situ.

Microbial-induced calcite precipitation(MICP) is a good approach for cementing residual soil to the bio-claystone with high strength，and hence，is widely applied in the subgrade improvement. However，the durability of the bio-claystone in the frozen regions is still uncharted. Therefore，it is necessary to study damage characteristics of the bio-claystone under freezing-thawing cycles，which will provide references for the further engineering application of MICP. Samples of the bio-claystone of shale residual soil were prepared after grouting period and rate were determined，and freezing-thawing tests with different moistures were performed. The damage characteristics and epigenetic features of the bio-claystone samples were analyzed，and the developing process of internal pore and fissure of the bio-claystone was investigated using the nuclear magnetic resonance(NMR). It is shown that the damage of the bio-claystone under freezing-thawing cycles is resulted from that the frost heave force of pore water exceeds the bond strength of MICP. Clastic particles fall down from the surface of samples due to the invalidation of cementation，and the damage area increases with increasing the water content and the number of cycles. T2 spectral curves of the bio-claystone remarkably vary with different water contents. The development of the internal crack of the bio-claystone can be evaluated by analyzing waveform alteration with cycles. It is also indicated that lower moisture causes the development of medium and small fissures while that higher moisture results in the continuous expansion of large fissures. The destruction of the bio-claystone gradually develops from the central part to both ends of the sample. With the increment of the cycle number， the growth rate of large fractures in the central part of the sample is greater than that at both ends. In the initial stage，the“sharp point”effect occurs in the middle of the T2 curve with high moisture. With increasing cycles，however，the“sharp point”gradually disappears and the curve becomes flat. Large fractures expand from the central part to both ends and then penetrat gradually，which finally causes the failure of the bio-claystone.