In alpine regions，freezing and thawing have an important influence on the acoustic emission(AE) characteristics and the frost resistance index of rock mass. Freezing-thawing tests and the uniaxial compression AE tests of granite specimens from cold areas were carried out. Results show that，as the freezing-thawing cycles increase，the frost resistance coefficient of granite specimens decreases and the mass loss rate gradually increases. With increasing the number of the freeze-thaw cycle，the end effect of the specimen becomes more obvious and AE counts at failure increase significantly. AE ring-down counts can be divided into three stages such as the contact period，the quiet period and the destructive period. With increasing freezing-thawing cycles，the duration of the contact period extends and AE ring-down counts increase obviously，the density of the ring-down counts at the calm period increases with many abrupt points，and AE ring-down counts are larger with a longer duration in the destructive period. As the number of the freezing-thawing cycle increases，the peak frequency points of AE signal are concentrated from the distracted state to a dominant peak frequency. When the sample is near to destruction，the dominant peak frequency of the AE signal gradually concentrates to the mid-high frequency band and the low-frequency of the AE signal reduces continuously. The probability density of the AE energy under different freezing-thawing conditions can meet the power law distribution. The critical index reflecting the scale invariance first decreases and subsequently increases slowly with increasing the number of the freezing-thawing cycles. The experimental results are of important significance for the application of AE technology in the cold region to identify and predict the stability of rock mass and to study the freezing and thawing damage mechanism of rock.

The self-developed “TCHFSM-I” large-scale true triaxial hydraulic fracturing seepage simulation device was used to study the crack initiation and propagation in coal-rock blocks under different stress conditions，and the hydraulic pressure and acoustic emission event evolutions were also analyzed. The results show that，when the difference of the axial stress and the minimum horizontal principal stress was equal or greater than 6 MPa，the hydraulic cracks can extend into coal across the interface，otherwise extend along the interface. The hydraulic pressure and acoustic emission response characteristics can well reflect the behaviors of hydraulic fractures across the interface. When the hydraulic cracks extend into the coal，the hydraulic pressure shows a significant secondary rise，and the cumulative number of the acoustic emission events increases significantly at a rate of 51.4%，most of which occur in coal. When the hydraulic cracks expand along the interface，the cumulative number of the acoustic emission events increases just by 6% and there is no secondary rise in fluid injection pressure. A crack expansion model crossing the interface，considering the angle between the crack and the interface，the interfacial friction and the stress state，was established，which can well describe and predict the crack expansion behavior crossing interfaces in hydraulic fractures. The research results in this paper can provide a technical guidance for efficient exploitation of coalbed methane.

The fracture parameters such as crack initiation time，crack propagation velocity and dynamic crack initiation toughness of different brittle materials will be different under impact loads. In this paper，the crack propagation characteristics of four types of common brittle materials including green sandstone，red sandstone，black sandstone and PMMA(polymethyl methacrylate) were investigated under dynamic loading.. The crack propagation velocity and crack initiation time were measured by utilizing TWSRC(tunnel with single radial crack) samples and crack propagation gauges(CPG)，and the initiation fracture toughness was calculated by experimental-numerical approach. The failure behaviors of the TWSRC samples were analyzed by the finite difference code AUTODYN. Through comparisons between the test results and the numerical results，some significant conclusions were obtained as follows. The crack propagation velocity increases with increasing the elastic modulus of the brittle materials and，conversely，the crack initiation time decreases. The dynamic crack initiation toughness of brittle materials increases with increasing the elastic modulus of the brittle materials. Under the same impact loading，the failure behaviors of three types of rock materials are greatly different from those of PMMA.

To investigate fracturing characteristic and cycle loading and unloading damage mechanism of the rock with rein detects in the sliding zone of Daguangbao(DGB) landslide，the surface area of veins were counted based on the technology of image recognition，and uniaxial compression and unloading tests were carried. The test results show that the interfaces of the vein mass are easy to form the potential failure plane of the specimens，and that the loading and unloading stress in the elastic stage can obviously cause the damage of the specimen and reduce the strength of the rock. The area ratio of vein mass has a great influence on the Poisson?s ratio，damage rule and peak strength of the specimen. Under the same loading and unloading condition，the bigger the area ratio of vein mass，the greater the Poisson?s ratio and damage are and the lower the peak strength is. The smaller the area ratio of vein mass，the smaller the Poisson?s ratio and the damage of the rock are and the lower the peak strength. The results reveal that the stress concentration caused by the non-compatible deformation of the veins during the earthquake has a very obvious effect on the damage and strength degradation of the rock.

To solve the problem that the traditional landslide displacement point prediction model cannot effectively describe the reliability of the prediction result，a landslide displacement interval prediction model based on different Bootstrap methods and KELM-BPNN model was proposed by introducing the method of interval prediction. In this model，firstly，the original dataset consisting of the monitoring information from various external trigger factors and landslide surface displacement was randomly sampled with an equal probability for B times and then，B dummy datasets were obtained based on different Bootstrap processes. B KELM models were trained to estimate the variance of the system error respectively and consequently，a BPNN model was trained to regress the variance of the random error. Finally，the variances of the system error and the random error，both obtained from the same Bootstrap process，were combined to construct the landslide displacement prediction intervals with different confidence levels. Through comparisons，an optimal displacement interval prediction model fitting in the deformation characteristics of actual landslides was proposed. Baishuihe Landslide，a typical colluvial landslide with step-like behaviour in the area of Three Gorges Reservoir，was taken as an example. The monitoring data of ZG93 and ZG118 from July 2004 to December 2013 were analysed. The results show that, compared with the traditional point prediction model，the developed model not only provides a relatively accurate point prediction result but also constructs a clear and reliable displacement prediction interval to cover the landslide displacement curve completely. In addition，the dynamic variation of the prediction interval width can be used to better quantify and explain the uncertain impact of the dynamic change of external triggering factors on the landslide evolution，which offers a new idea or option for the forecasting and the early warning of landslides.

The uniaxial stress-strain tests of granite under different temperatures and cyclic loads were performed utilizing the multi-functional rock high temperature triaxial testing machine，and the effect of the temperature and the cyclic load on the mechanical properties of granite was revealed. The results show that the uniaxial compressive strength and elastic modulus of granite decrease generally with increasing the temperature. The ultimate strain changes with the temperature in W shape. Specifically，the ultimate strain of granite firstly decreases with rising the temperature from 25 ℃ to 200 ℃，secondly increases from 200 ℃ to 300 ℃ ，thirdly decreases from 300 ℃ to 500 ℃ and then increases from 500 ℃ to 600 ℃. The elastic modulus of granite increases generally due to cyclic loads，and the increase amplitude is different with different temperatures with the minimum and maximum values at 100 ℃ and 400 ℃ respectively. The increase of the elastic modulus mainly occurs in the second stress cycle but is not obvious from the second to the 50th stress cycle. At 25 ℃ and 600 ℃，granite samples fail after a limited number of stress cycles，and the strength is lower than that without stress cycle. However，the strength of the samples after stress cycle shows different degrees of increase at other temperatures. The ultimate strain of granite subjected to 50 stress cycles is greater than that without stress cycle at 100 ℃ and 400 ℃ but changes slightly at other temperatures. The research results have important theoretical significance and application value for the study of engineering stability under the simultaneous action of temperature and cyclic stress.

Aiming at the problem that it is difficult for high strength cable bolts to come into action in roadway roof with water-bearing soft rock and taking Lijiahao coal mine as an example，theoretical analysis，numerical simulation，laboratory experiment and field test were adopted to propose a method for improving the anchorage effect of cable bolts. A new device which is easy to install and simple in structure without affecting the normal installation of cable bolts was developed and the anchorage improving mechanism of the device was revealed. The results indicate that， as the distance between the water-bearing rock stratum and the roof changes，it is difficult to determine the reasonable anchorage position. When cable bolts are anchored in irregular distribution soft rock stratum，the anchoring force significantly declines and may not meet the anchoring requirements. The device including mixing structure and sealing-lifting structure can increase the uniformity and density of the resin grout to improve the anchoring force. The field test demonstrates that the anchoring force can be increased by more than 30% compared with the normal anchored cable bolts. The device can promote the roof to form a stable anchorage structure and hence，reduce the roof deformations obviously and enhance the roof stability.

There exists a large error in conventional stimulated reservoir volume (SRV) calculation method which adopts relatively regular shapes to build 3D envelop. An integrated methodology that utilizes the octree method to generate irregular tree mesh structure according to the density of microseismic events was presented，in which the stimulated reservoir volume is obtained by summing up the volumes of non-empty nodes in the tree structure. The method was validated by analog events generated by Monte Carlo simulation and application of eighteen wells of Kunbei oilfield. It was found that the octree method can be used to envelop the event cloud perfectly and eliminate effectively enough the error of unresponsive zones during microseismic monitoring. The octree method fully considers the impact of event density on SRV calculation in different monitoring areas and determines hierarchies of tree structure according to local event density. Hence，the calculation result conforms to engineering knowledge. Engineering applications show that the method has a high computational efficiency for large scale microseismic data，and that the calculated SRVs are consisted with the daily liquid production of 18 wells in Kunbei oilfield. Compared with the conventional approach，the developed method provides a more reliable quantitative index for hydraulic fracturing evaluation.

With the increase of the mining depth，the deterioration of the ore rock condition and mining environment，rockbursts are becoming an inevitable and frequent dynamic disaster in the process of underground metal mining. Based on a comprehensive review of status quo，influencing factors，typical characteristics，types and grades，and evolution process of rockbursts in underground metal mines at home and abroad， the prediction and control technologies of rockburst in roadway and stope are discussed and analyzed respectively. The results show that the world can be roughly divided into 6 rockburst zones. At present，rockbursts have occurred or maybe occur in more than 20 underground metal mines in China，which are mainly distributed in the shape of “S” along the coast from northeast to southwest，and the number of rockburst mines increased in the last 30 years. The influencing factors of rockbursts in underground metal mines can be divided into three types including internal factors of class I，external factors of class II and aggravating factors of class III，which are both independent and interacting. The rockburst in underground metal mines can be divided into two categories based on the project type，that is，the roadway rockburst and the stope rockburst. The engineering protection of the roadway rockburst should follow the basic principles of “combination of active and passive supports，combination of rigid and flexible supports，and multi-method coordinated support rather than single support”. The prevention and control of stope rockburst，which is still at the research and exploration stage，can be carried out from the aspects of mining method and technology，stope layout and mining sequence. Backfill method is a mainly solution of ground pressure disasters such as rockbursts in deep mining. The prevention and control of rockbursts in underground metal mines should run through the whole mining process. It is an urgent need to establish a long-term monitoring and feedback mechanism and to form corresponding technical specifications in this field. Finally，the problems and key research contents in the study of rockburst in underground metal mine discussed and analyzed，which can provide references for the establishment of rockburst prevention system and the design research of mining engineering in this field.

In order to investigate the difference of mechanical properties of deep-buried soft rock under different stress paths，the indoor triaxial loading test and confining pressure unloading test with a constant axial stress under different confining pressure levels，different unloading stress levels and different unloading rates were performed on the deep-buried soft rock samples from the right bank of the Danba Hydropower Station，and the microtopography of the unloading failure surface of the rock samples was scanned. Deformation，strength and failure characteristics of rock samples under different conditions were discussed. The results show that，compared with the triaxial loading test，the strength and the peak strain the soft rock with the same grade confining pressure under the unloading condition are reduced，and the stress-strain curve is converted from ductility to brittleness. The peak axial strain，the ultimate strength and the residual strength of the soft rock are positively correlated to the unloading stress level and the unloading rate. Compared with the Hoek-Brown empirical strength criterion，the Mohr-Coulomb strength criterion can better describe the soft rock strength characteristics. Different stress paths have different effects on the shear strength parameters. The unloading rate has a more significant effect on c value while the unloading stress level has a more significant effect on ? value. The failure mode of soft rock under both loading and unloading is shear failure. There is no derivatized microcrack except for the main crack under loading，but the low unloading stress level is more likely to induce new cracks than the high unloading stress level. The larger the unloading rate，the more severe the damage is. When the sample fails under a lower confining pressure unloading，there is a higher degree of freedom of failure surface microtopography evolution and the roughness of the failure surface is larger.

In order to better study the prevention and control mechanisms of multi-stage grouting steel pile group， large scale field model tests were carried out to analyze the anti-sliding performance of multiple segmented grouting steel pile group from the aspects of soil pressure and bending of steel pipe. Grouting effect，pile group effect and failure mode were also discussed. The test results show that，while a slope is reinforced by multiple segmented grouting steel pile group，“root shaped” anti-sliding cement columns around the grouting steel piles form，which can efficiently enhance the strength of the soil around the piles and improve the anti-sliding ability of the pile group. The horizontal anti-sliding force of every pile of multiple segmented grouting steel pile group structure with three rows of pipes of 6.0 in length was 1.1×104 N larger than that of single row piles，and the lateral bearing capacity of single pile increases by about 10.5% considering the group pile effect. Because of tat the bending failure of every pile of pile group happens near the sliding surface，it is suggested that the reinforcement ratio of the piles near the sliding surface should be properly enhanced to improve the anti-sliding ability.

In order to investigate the leakage law of underwater shield tunnel joints，a set of model test device was designed to observe the leakage process of shield tunnels under constant water pressure，and tests for the leakage law with different assembly patterns，leak widths and locations were carried out. The influence of the leakage on soil stress and deformation around the leak was also revealed. The experimental results show that the critical width of the leak is almost unaffected by the leak location. The water leakage under the critical width is non-convergent and related to the leakage direction. The leakage rate at the tunnel hance is about twice that at the tunnel vault. However，the sand leakage of all leaks is convergent within 4 min and is related to the formation of the soil stress arch. The increment of the soil pressure around the leak at the arch foot of the tunnel is the largest，the soil stress arch is the most difficult to stabilize，and the amount of sand leakage at the arch foot is about three times of that at the tunnel vault. The characteristic particle size of sand leakage decreases gradually from the original gradation，and eventually smaller particles are absorbed on the skeleton of large particles and no longer leak out. The soil pressure around all leaks increases by approximately 60%，and the increment of the soil pressure is positively related to the leaking sand-water mass ratio. The surface settlement is the most obvious when the tunnel arch foot is leaking，and the average influence range of the surface settlement is wider when the staggered pattern assembly tunnel is leaking.

As a kind of suspension liquid，cement slurry has obvious characteristics of the bleeding. Once the bleeding occurs，the viscosity and the density of the slurry change obviously，which leads to the viscosity and the density of the slurry in time and space are not uniform at the penetration zone. In order to accurately describe the grouting process of the fracture under the function of the bleeding，a theoretical model of fracture grouting，considering the characteristic of cement bleeding，was established under the constant grouting rate，the expressions of the diffusion radius and the pressure gradient of slurry were derived，and a calculation method of fracture grouting considering the cement bleeding was put forward. Based on MATLAB programming，the distribution calculation of the bleeding rate and the grouting pressure in time and space was realized. The rationality of the theoretical model was verified by using the self-developed fracture grouting model test platform. The results show that the bleeding rate of the slurry shows a nonlinear change with the increase of the penetration length of the slurry. With increasing the water-cement ratio，the spatial distribution gap of the bleeding rate increases obviously. The grouting pressure calculated by considering cement bleeding is obviously higher than that of the unconsidered. With increasing the water-cement ratio of the slurry，the difference of the grouting pressure between two cases of considering and without considering cement bleeding rises. Comparison between the test results with the theoretical calculated values indicates that the grouting pressure obtained from the theoretical calculation is 1.2–1.5 times of the model test value. The established theoretical model can better describe the diffusion process of cement slurry in fracture grouting considering the effect of bleeding.

In order to study the difference between the equivalent viscoelastic method and the elastoplastic method in earth-rock dam dynamic analysis，the Shen?s dynamic model and the generalized plasticity model were compared in several aspects of acceleration response，dam displacement history，residual deformation and slab dynamic stress under the same condition. Results show that，compared with the viscoelastic method，the acceleration amplifications at the top and at the lower middle of the dam calculated by the elastoplastic method are respectively slightly smaller and larger. Because the residual displacement is not considered in the viscoelastic method，the calculation displacement history is largely different from that obtained by the elastoplastic method. The residual deformation calculated by the viscoelastic method is rather consistent with the elastoplastic method，but the dam shrinkage evaluated by the elastoplastic method is more identical to actual earthquake damage. Calculation results by the viscoelastic method show that tensile failure will occur at the top part of the slab during the earthquake，but the results by the elastoplastic method reveal that compressive failure will occur at the middle of the slab. The main reason is that the viscoelastic method does not include the residual displacement component which results in the dynamic stress of the slab distorted. It is indicated that the elastoplastic method can effectively overcome the defects of the viscoelastic method.

The mechanical properties of loess are very sensitive to the change of the water content，and the immersion of water-sensitive loess stratum has obvious influence on its engineering structure. In order to study the influence of the collapsibility of large-thickness loess stratum induced by immersion on the subway tunnels，a model box which can reproduce the conditions of basement and surface immersion was developed，and the tests of tunnel mechanical response under different immersion conditions were carried out systematically. The influence mechanism of loess immersion on subway tunnels was studied，and the control standard of residual collapse settlement of the foundation was suggested. The results show that，with the increase of the immersion depth，the redistribution of the soil pressure around the tunnel will be caused by the local immersion of the foundation and the surface，and that the variation trend of the soil pressure is not uniform. The soil pressure decreases with the immersion depth under the condition of foundation all-range immersion but increases with the immersion depth in the case of surface all-range immersion. The change trend of the soil pressure of the both cases is relatively uniform. Foundation local immersion leads to a local decrease of the bearing capacity and hence，results in an irregular change of the bending moment of the tunnel lining. The uniform immersion of the whole basement leads to a uniform decrease of the bearing capacity，and the bending moment at each point of the tunnel lining changes relatively uniformly. The strength of the stratum above the tunnel losses partly due to local immersion，and the load gradually acts on the lining of the tunnel which causes a rapid increase of the bending moment of the lining. The bending moment increases with increasing the immersion depth under surface uniform immersion condition. The horizontal and vertical displacements of the tunnel are obvious when the foundation and the surface are partially immersed. When the foundation or the surface is fully immersed，the vertical displacement is predominant but the horizontal displacement is not obvious. The tunnel displacement caused by the foundation immersion is larger than that caused by the surface immersion. The differential settlement caused by the local uneven immersion will have an additional twisting effect on the tunnel，which is more harmful to the tunnel. When the collapsible layer of the tunnel foundation is 30 cm，only 10 cm of collapsible soil has little effect on the whole tunnel. It is suggested that the residual collapse settlement of 10 cm is allowed and the treatment depth of the collapsible foundation is 20 cm. The research results can be used for reference in the preliminary design and post operation of subway tunnels in large thickness loess area.

According to the characteristics of good uplift resistance of flexible semi-excavated foundation，which is suitable for better undisturbed soil and deeper underground water level condition，the uplift bearing capacity of the new type of foundation was studied. Considering different soil properties，depth-diameter ratio and cone spreading angle of new foundation，4 sets of test models of undisturbed soil were designed and manufactured，and the uplift stable bearing capacity tests were carried out. Tests results show that deformation of the foundation due to the uplift load experiences three distinct stages such as linear，elastic-plastic and failure stages and that the foundation fails in the form of the upheaval of the ground soil. The nonlinear behavior of uplift stable bearing capacity of the new flexible semi-excavated foundation was simulated，and the difference of deformation characteristics and force transfer mechanisms of the new foundation and the traditional excavated foundation was analyzed. Comparisons between soil weight method and shear method were performed. It is shown that，under the condition of a large depth-diameter ratio，the bearing capacity calculated by the soil weight method is 20% larger than that obtained by the shear method and hence，the soil weight method is unsafe. The calculation theory of the uplift bearing capacity of the new foundation was proposed based on the hypothesis of soil arc sliding surface considering the shear method，and the theoretical method of the uplift bearing capacity of the foundation was verified by test and simulation results.

To study the difference of site dynamic parameters and seismic response between unfrozen and frozen seasons，the characteristics of microtremors in frozen and unfrozen seasons were analyzed by 3-component observation in Harbin sites. The effect of frozen soil on site predominant frequency，site amplification factor，equivalent shear wave velocity and site classification were studied by microtremors H/V method. A method for estimating the thickness of the frozen soil was proposed. The results show that the frequency of the horizontal component of microtremors increases because of the frozen soil but the increase of the vertical component is not obvious，and that the increases of the predominant frequency are different among sites even if in the same area. The increase of the site predominant frequency is correlated with both the thickness of the frozen soil and the stiffness of site surface soil. The amplification factor of the site decreases due to the frozen soil，and the decease of the amplification factor is correlated to the stiffness of site surface soil rather than the thickness of the frozen soil. The thickness of the frozen soil can be estimated according to the shear wave velocity of the site and the predominant frequency of the H/V spectra ratio. Due to the frozen soil，the equivalent shear wave velocities，vs20 and vs30，increase by 13% and 11% on average in six sites respectively. The increase of vs20 does not affect the site classification of class II，but can change the site of class III into class II with vs20 of nearly 250 m/s. The increase of vs30 during the frozen season does not affect the site classification of class D.

For large diameter thin-wall pipe piles，the soil plug at the pile toe and the pile three-dimensional effect should be taken into account during low-strain testing. A coupled dynamic model of large diameter thin-wall pipe and pile-soil plug considering the pile three-dimensional effect was presented，and an analytical solution in Laplace domain and a semi-analytical solution in time domain were subsequently deduced subjected to the longitudinal vibration. Comparisons between the solution and the existing solution based on Rayleigh-Love rod model were carried out. It is indicated that the two solutions are identical，which verifies the reliability of the one-dimensional rod model considering the lateral inertia effect in solving the dynamic problems of a pipe pile with soil plug. The influence of the combinations of the outer radius and the wall thickness of the pipe pile and the height of the soil plug on the low-strain testing results adopting the presented solution. The study can provide theoretical support and practical guidance for the engineering test on site.

In view of the current situation that the relative density test results are limited to indoor tests，site large-scale density barrel tests were carried out on granite rockfill material from a certain engineering for the first time. The effect of different scale methods on the dry density was investigated，and the influence of the dry density scale effect on the sample preparation standards for indoor scale tests and on-site compaction quality evaluation was revealed. The test results show that，due to the truncation error of the grading after the scale and the difference of the particle shape，the dry density of the rockfill increases with increasing the maximum particle size and the scale effect still exists even if the similar scale is used，but that the scale effect is significantly reduced when the maximum particle size reaches 300 mm or more. The measured dry density of each group of grading piles with different maximum particle diameters have maximum values，and the corresponding critical fractal dimension has nothing to do with the maximum particle size of the gradation. the mixed scale method commonly used at present reduces the fractal dimension of the original graded rockfill and deteriorates the filling relationship between the particles，and as a result，the dry density under the same relative density condition deviates from the scene more obviously than the test result of the similar grading method which is difficult to reasonably reflect the physical and mechanical properties of the original graded rockfill. It is shown that，using the same relative density standard sample preparation as the on-site compacted rockfill body，the compression modulus obtained by the indoor compression test is reduced by 90%–220% compared with the direct filling of the dry density sample on site and that the indoor test results without considering the density scale effect significantly overestimate the mechanical properties of the rockfill on site. The indoor test results used to directly calculate the relative density of the original graded rockfill body overestimate the compaction degree of the rockfill body，and even the calculation value of the relative density may be greater than 1.