This paper presents the experimental study of the granite rockburst under four different unloading rates. With the help of the collected fragments measurement after tests, the scale features of fragments can be obtained. Acoustic emission system is used to monitor the internal damage of the rock; and the typical time-frequency analysis tool is applied to the major frequency extraction of every acoustic emission (AE) waveform. The tested results indicate that the total number of fragments and the portion of fragments with blocky structure and plate shape have a decreasing trend with the unloading rate dropping down. The AE major frequency band is found to be located in the moderate low frequency band and it is up-shifting as the unloading rates decrease changing from intensive broadband to discrete narrowband. According to the distribution of RA and AF, the crack type evolution can be determined. During the unloading rockburst test, the cracks generating in the specimen are mainly tensile cracks. Further decreases in unloading rate do appear to drive the AE signals reduced indicating crack amount decrease. All these results will be helpful for us to understand the rockburst mechanism under different unloading rates and prove the feasibility of adjusting excavation speed to reduce rockburst risk in field site.

This paper presents an experimental investigation on hydraulic conductivity of coarse and fine sands from a deep underground mine under high confining pressures using a static triaxial permeability test system. A series of experiments for hydraulic conductivity is performed under high confining pressures to investigate the correlation between the hydraulic conductivity and the confining pressure in the same hydraulic gradient, the relationship between the hydraulic conductivity and hydraulic gradient in the same confining pressure, the differences between hydraulic conductivities from the confining pressures by stepwise loading test and the direct loading test under the same hydraulic gradient. The results show that the hydraulic conductivity of the coarse sand and fine sands are all gradually decreased with the increasing confining pressure under the same hydraulic gradient. Under the same confining pressure, the hydraulic conductivity of the sand increases gradually with the increasing hydraulic gradient. It is also found that the hydraulic conductivity of the sand with stepwise loading is much higher than that with the direct loading under the same hydraulic gradient. The volume change and grain size compositions of the sand sample before and after the test are studied to find the reason why the hydraulic conductivity changes with the confining pressure. The results indicate that the volume of the sand sample decreases during the process of confining pressure increasing and permeation, which lead to the decreasing hydraulic conductivity. The grain size compositions of the sand samples before and after the permeability test show that some sand grains are crushed under high confining pressure, which increase the finer particles and decrease the porosity of the sample therefore decrease the hydraulic conductivity.

The infiltration characteristics of soil under the action of heavy rainfall is an important part to study the developing process of landslide debris flow and soil landslide. A soil cylinder experimental facility for infiltration test under artificial rainfall is prepared to do infiltration test for strongly weathered mudstone under six rainfall intensities, i.e. 10, 20, 30, 40, 50 and 60 mm/h, and the longest rainfall duration is 105 minutes. Three conclusions are drawn as follow. Firstly, the infiltration process can be divided into non-compressive infiltration, compressive infiltration, and saturated infiltration stages. Meanwhile, the infiltration rate will close to be a constant along the rainfall duration in the non-compressive infiltration and saturated infiltration stages, and it will reduce quickly in compressive infiltration stage. Secondly, the infiltration interface in the soil is defined as infiltration front, and it contains original infiltration interface and final infiltration interface. Then, the relation is discussed between the depth of infiltration front and rainfall intensity, the bigger the rainfall intensity is, the bigger the amplitude between two infiltration interfaces is. Thirdly, a rainfall infiltration formula is built to express the infiltration process of Jurassic strong weathering mudstone in Chongqing city. The results have positive effect for the study of constructing the forecasting model of rainfall-induced type landslide and slope debris flow in Chongqing city.

The underlying soil possesses the nature of variation in consolidation degree before subway operation, which will result in the change of pore pressure as well as the differential settlement. Hangzhou saturated soft clay is tested by dynamic triaxial test system to find the effect of consolidation degree, consolidated stress and cyclic stress ratio on the development of pore pressure. A new pore water pressure model considering the initial consolidation degree and the threshold cyclic stress ratio is proposed on the basis of existing research findings. The results show that under cyclic loadings, the development of pore pressure undergoes higher regularity than that of shear strain. The higher the consolidation degree is, the slower the pore pressure increases. Furthermore, the pore pressure will be stabilized at a lower level with the increment of cyclic times. Taking pore pressure delaying into consideration will lead to more desirable results while predicting the pore pressure and long-term settlement of the tunnel. The obtained pore pressure model can well simulate the pore pressure development under subway loadings.

Based on the practical situation that the opening of outburst mouth is man-made controlled in experiments of coal and gas outbursts, the simulation device of outburst is designed and developed which can change axial pressure, confining pressure and pore pressure. The outburst mouth can open by itself. Sunjiawan coal mine in Fuxin is a typical high gassy mine as example, the whole processes of outburst induced are simulated by experiments on conditions of joint action of stress and gas pressure near working face when mining depth is respectively 900 m, 1 100 m and 1 300 m. In experiments, axial pressure and confining pressure are used to simulate ground stress. And pore pressure is used to simulate gas pressure. According to similarity theory, axial pressure and confining pressure are determined in advance on condition of 900 m, 1 100 m and 1 300 m. With the step-by-step increment of pore pressure, the gas pressure of outburst is obtained. The relationship curves are presented. The results show that the relationship curves are all power exponent among mining depth, axial pressure, confining pressure, gas pressure and outburst distance, outburst intensity. With depths increasing, the influences of stress and gas pressure on the intensity increment of gas outburst are gradually decreased. The effect of the gas pressure on outburst presents three stages characteristics, dramatic stage, steady stage and slow stage of impact increasing. The gas pressure of 0.75 MPa is the threshold influenced on maximum rate of outburst. That is also cut-off point of gas pressure between abnormal and steady region, corresponding mining depth of 350 m, which is consistent with previous theoretical results. On the basis of analysis above, it can be presented that with deep mining, the frequency of coal and gas outbursts will increase on the joint action of stress and gas pressure. But the increment of impact strength and damage will decrease. The conclusions will have reference significance to mechanism, forecasting and prevention of gas outburst for Sunjiawan coal mine.

For the study of the flow behavior of rock avalanches under the effect of entrapped air, the Xiejiadianzi rock avalanche is studied with a series of experiments, equipped with a fluidized bed designed by authors. Based on the experimental data, the following results are reached: (1) For materials having wide grain size distribution (ranging from 0.1 to 7 mm), sharp irregular shapes, and high fine-grain content at its lowest part, an obvious bubbling control characteristic, not a linear increasing trend, is displayed as the quantity of air increases. Variation of the positions of bubbles or the air cushion layer causes significant differences in bed pressure drops. (2) When air quantity is low, the deposit presents a high stability with limited air holes observed. As the increase of air quantity, the fluidization intensity of the deposit increases obviously with some fluidization characteristics observed, such as dense sandy cloud, air holes, and ridges, which are similar to the phenomena observed in field rock avalanche deposits. (3) For such irregular shaped debris, bridging phenomenon is easy to form, which can strengthen the stability of deposit and prevent the escape of entrapped air. When air quantity is high enough, an air cushion effect can be observed at the bottom of deposit with air born system formed.

According to the equal strain axisymmetric consolidation theory of sand-drained foundation developed by Xie and Hansbo, analytical solutions to the axisymmetric consolidation equation with bottom vacuum preloading are derived in this study as the vertical water flow in soil is neglected for the actual loading boundary condition that the vacuum preloading locates at the bottom. Based on the analytical solution formation process of excessive pore pressure axisymmetric consolidation control equation, a comparison between this new developed model and the current solution is carried out gradually. In comparison of the new model outputs and the experimental results by laboratory test, the excessive pore pressure distribution in vertical direction and the consolidation ratio development trends for excessive pore pressure dissipation can be obtained by the new developed analytical model, and it also can be concluded that the calculated results show a good agreement to the laboratory and site experimental results. Therefore, the analytical solution can be further applied to practical engineerings as basic theoretical foundation, which also promotes the application of bottom vacuum preloading method in soft foundation reinforcement engineering.

Mercury injection test on Zhanjiang natural soft clay and compressed soil is conducted to obtain the microscopic deformation mechanism of structured soft clay. Evolutions of pore distribution, size, and structural characteristic parameters under different consolidation pressures are analyzed; the pore morphology is further quantitatively analyzed by SEM image, which is explained and testified by fractal theory. The results show that, a positive correlation is shown between the sensitivity of each pore size to external forces and pore volume content. The distribution density of the fine pores might be exaggerated while the one of macro pores might be underestimated in mercury injection test for the bottleneck effect. Pore distribution is affected by structure. When consolidation pressure increases to yield pressure, pores of 0.01-0.50 μm are changing obviously, pore connectivity becomes worse, pore size decreases, isolated pores increase, and limits between pore sizes become unobvious. Zhanjiang soft clay has multi-fractal characteristics, the limits for determining micro-pores, interparticle pores and isolated pores are 0.01 μm and 0.50 μm. Pore size division standard is given.

Supporting the excavation face is the most important role for slurry in the field of engineering, such as diaphragm walls, bored piles, and slurry shield tunneling. To achieve the function, a filter cake has to be formed on the soil, and the soil and pore water pressure have to be counteracted by slurry pressure. And the essence of filter cake formation is that the slurry infiltrates in the stratum. To reveal the phenomena and laws of slurry infiltrating into the soils, a series of slurry infiltration tests is carried out on sand samples with different permeabilities. Based on the test results, three typical seepage curves are discovered, and the shapes of slurry particles accumulated on the ground surface are also divided into three types: filter cake, filter cake with an infiltrated zone, and only an infiltrated zone without filter cake. Meanwhile, a corresponding relationship is discovered between the types of slurry seepage curves and the shapes of slurry particles accumulated on the surface. In addition, the seepage discharge during slurry infiltrating into the sand reflects the type of slurry infiltration. And it can be used as a criterion to determine whether a filter cake is formed on the surface.

The initial anisotropy of natural soft clay tends to have a significant influence on its subsequent cyclic behaviors. The current elastoplastic constitutive models for cyclic behaviors of saturated clay always adopt an elliptic yield surface similar to the one in the modified Cam-clay model. However, studies have demonstrated that these kinds of models which adopt an elliptic yield surface are not suitable for predicting the characteristics of K0-consolidated soils under the extension state, due to its over-predicted elastic region. In this paper, within the framework of the generalized isotropic hardening rule, by introducing the initial anisotropic tensor to the formation of the bounding surface and combining with the transformed stress tensors which are based on the spatially mobilized plane (SMP) yield criterion, a new bounding surface plasticity model for saturated clay with initial anisotropy is proposed. The predicted results by the model for the monotonic and cyclic triaxial tests on both isotropically and anisotropically consolidated clays demonstrate that the bounding surface model can reasonably describe the initial anisotropy and the subsequent cyclic behaviors of saturated clay.

Water pressure could stimulate rock crack and accelerate the process of rock failure, this has an important influence on the deformation characteristics and failure mechanism of rock. A hydro-mechanical coupling test of sandy rock is conducted at different confining pressures by MTS815 Flex Test GT rock mechanics test system and PCI-Ⅱ acoustic emission (AE) system. The experimental results are displayed as follows: AE activity represents different characteristics with the loading time and stress changing during the total loading process. With the increase of water pressure, the AE activity is more concentrated and strength is higher after the stress reaches the peak strength of rock. But concentration and strength reduce with the increase of confining pressure. At the same confining pressure, the AE counts and energy increase as the water pressure increases. As the water pressure increases, the number of cracks enhances and the degree of concentration of crack is higher in the 3-D location of AE figures when the rock is unstable failure. At the same time, the failure angle decreases on the macroscopic failure morphology. These results reveal that the mechanism of rock failure changes from suppression of shear to suppression of tension rift; its plasticity is weakened and brittleness is enhanced under hydro-mechanical coupling process.

In order to find the effect of total phosphorus on physico-mechanical performance of clay, samples have been tested with deionized water and total phosphorus solution with different concentrations in laboratory, and the interaction mechanisms of clays and total phosphorus are revealed by mineral and microscopic analysis. The results make clear that the total phosphorus has significant influences on physico-mechanical performance of clay: the plasticity indices of samples decrease with the increasing concentration of total phosphorus solution, the effective cohesive strength increases and then decreases, and the effective friction angle increases with the increasing concentration; the strain hardening phenomenon appears in the stress-strain relationships, and the variation of stress-strain curve of samples soaks in deionized water and total phosphorus solution is almost the same. The peak shear strength of samples manifests as a trend of increase and then it decreases with the increasing concentration of total phosphorus solution. The mineral composition, microstructure and physico-mechanical performance of clays are affected by the interaction between total phosphorus and clays, including ion exchange, cementation, microbial decomposition as well as the dielectric constant and viscosity of pore solutions.

Interface strength parameters are the key technical indices of the design and stability analysis of reinforcement. The pullout test is widely used for its better simulating of the field reinforced behavior. Through pullout test and direct shear test, the research focuses on the law and mechanism of the pullout (shear) rate’s influence on reinforcement interface characteristics and hydraulic fill sand, and the reinforcement effect of different fillers and different geosynthetics are discussed. The results show that: with the increase of pullout (shear) rate, the shear strength of sand-geotextile-sand interface decreases greatly while clay-geotextile-sand and sand-sand interfaces change little. From the perspective of strength index, sand-geotextile shear strength decreases mainly caused by the decrease of cohesive force; clay-geotextile shear strength increases mainly caused by the increase of friction angle; shear rate has little influence on hydraulic fill sand. Friction angle of reinforced soil is less than that of the soil itself. The interface characteristics of reinforcement are influenced by both pullout rate and normal stress level, related with type of geosynthetics and characteristics of soil. The choice of friction parameter for design and evaluation of reinforced structure should accord to the size of cohesive force.

The waterproofing properties of compacted clay barrier at landfill site will be greatly weakened by crack which is induced by the waste’s differential settlement. In order to reveal the effects of preferential flow on the anti-seepage performance of cracked barrier, the crack is treated as high-permeable porous medium, and a simplified saturated/unsaturated seepage model of the barrier with a single crack is developed to study the process of preferential flow. In addition, the influence of crack position, depth, width and permeability coefficient on the anti-seepage performance of the barrier is comparatively analyzed. The results show that the infiltration process can be divided into three stages: early stage, penetrating stage and steady stage. Besides, the bottom crack has little influence on the barrier’s anti-seepage performance, but it is greatly affected by upper or fully penetrated crack. The breakthrough time will be significantly shortened with crack depth increasing until the crack is thoroughly penetrated; and it is better to keep the crack depth under 0.1 time of the barrier’s thickness to ensure its anti-seepage performance. What’s more, with the increase of crack width and permeability coefficient, the water breakthrough time will be rapidly shortened and the steady leakage will increase respectively; and they tend to be stable when they are reaching a certain value. It also shows that the barrier’s anti-seepage performance would significantly deteriorate as soon as the crack is fully penetrated; and the steady leakage will increase linearly with the increase of crack width and permeability coefficient.

Water flow and heat transfer processes in fractured rocks may be encountered in several engineering disciplines, such as geological disposal of radioactive waste, geothermal development, petroleum exploration, etc. Currently existent theoretical models and calculation methods for water flow and heat transfer in fractured rocks are almost exclusively based on the assumption of parallel smooth fracture walls, without considering the effects of local fracture wall asperity contacts on water flow, water-rock heat exchange and heat transfer. The following studies are presented in this paper. Firstly, dealing with water flow in a fracture with rough walls, the Reynolds lubrication equation and the Hele-Shaw model of a fracture with local wall asperity contacts based on the Stokes equations are expounded; solutions are sought by using the PDE tool of the MATLAB software, and compared with the Walsh formula of the effective hydraulic aperture of a rough walled fracture. Secondly, the similarity between the water flow and heat transfer in a fractured rock with local fracture wall asperity contacts and the water flow and heat transfer in a fractured rock with fills is analyzed; the condition for applicability of the instantaneous local thermal equilibrium is proposed; and the time and its influencing parameters for local thermal equilibrium between the local fracture wall asperity contacts and the flowing water in the fracture are computationally analyzed under the premise that the Biot number condition can be satisfied by the local fracture wall asperity contacts. Lastly, assuming instantaneous local thermal equilibrium between the local fracture wall asperity contacts and the flowing water in the fracture, the distributions of temperatures in the flowing water and the rock matrix are calculated using an existing analytical solution for water flow and heat transfer in a fractured rock with fills, and the effects of the ratio of local asperity contact area, the fracture aperture and the averaged water velocity on the temperature distributions are analyzed, which indicate, under the prescribed conditions, (1) that due to the heat exchange between the local fracture wall asperity contacts and the flowing water in the fracture, the range of influence of the flowing water on the temperature of the rock matrix decreases with the increase of the ratio of local asperity contact area, whereas the degree of influence of the rock matrix on the temperature of the flowing water in the fracture increases as the ratio of local asperity contact area increases; (2) the influences of the fracture aperture and the water velocity on the temperatures of the rock matrix and the flowing water in the fracture are consistent in that the range of influence of the flowing water on the temperature of the rock matrix increases with the increases of the fracture aperture and the water velocity, whereas the degree of influence of the rock matrix on the temperature of the flowing water decreases as the fracture aperture and the water velocity increase.

On the basis of a series of uniaxial compressive tests on frozen silty sand under different initial ice contents and strain rates, the uniaxial compressive deformation and strength characteristics of frozen silty sand are discussed and analyzed. The results show that with the initial ice content increasing, the plasticity of frozen silty sand is enhanced and the stress-strain behavior gradually tends to the characteristic of remolded ice after the initial ice content increases above 210.1%, and the relationship between stress and strain can be described by using the revised Duncan-Chang model. With initial ice content increases, the initial tangent modulus of frozen silty sand nonlinearly rises when the strain rate is 0.083×10-3 s-1 or 0.467×10-3 s-1; but it originally increases to a maximum value and then begins to decrease when the strain rate is 0.667×10-3 s-1. A log function can be used to describe the relationship between the uniaxial compressive strength and initial ice content, that is, the strength first increases and then gradually tends to be stable as the ice content augments from 32.9% to 304.0%. This study can supply a basis for evaluating the stability of subgrade in permafrost region with ice-rich soil.

A series of undrained tests is carried out on Hangzhou soft clay with hollow cylinder apparatus. The stress paths which include shearing test under different-fixed principal stress directions for the intact soft clay and principal stress rotation for intact and remolded soft clay are designed to study the non-coaxial development behavior of soft clay as well as the influence of intermediate principal stress parameter b, initial deviatoric stress and induced anisotropy on non-coaxiality. The results show that the non-coaxiality of soft clay is similar to that of sand, but they are far from identical. The non-coaxial angle is quite small in fixed shear tests; and it is dependent on the loading directions; however, affected by the development of deviatoric stain, the non-coaxial angle is not 0° when the specimen is close to failure. Regardless of intact soft clay or remolded soft clay, the non-coaxial angle fluctuates with the increase of principal stress orientation α, of which the cycle period is 90°. The non-coaxial angle basically decreases with the increase of coefficient of intermediate principal stress b, but this effect is not quite remarkable. The deviatoric stress has certain effect on the angle of non-coaxial as well as its development trend. As to the test of remodeled soft clay, it shows that the non-coaxiality is not only entirely determined by the inherent anisotropy, the induced anisotropy also has a great impact.

In order to identify the deformation and failure mechanism of rock mass with high strain energy under fast unloading condition, Jinping marble rockburst tests are designed, and the macroscopic failure characteristics and acoustic emission(AE) processes are studied. Firstly, based on previous characteristics of true triaxial rockburst tests, true triaxial rockburst tests with entire process and without entire process are done, and a detailed process and AE characteristics are analyzed. Secondly, progressive failure is explained by comparing macroscopic failure characteristics of true triaxial rockburst tests with entire process with that of true triaxial rockburst tests without entire process. Conclusions are drawn as follows: in marble rockburst test, the macroscopic failure of rock specimen varies from outside to inside; tensile cracks appear earlier than shear cracks, and isolated rock fragment, which is confined by tensile cracks (or free face) and lapping shear cracks, peels off with or without a initial speed; the phenomenon that rock powder only exists on the shear crack planes demonstrates that a considerable strain energy dissipates, accompanying expansion of shear cracks; compared with other classification and mechanism of rockburst, a progressive failure view of rockburst in this article explains rockburst mechanism reasonably.

As a new foundation for wind turbine on land, piled beam-slab foundation has a broad prospect .The optimized structures properly can reduce costs. To investigate the bearing and deformation characteristics of piled beam-slab foundation under vertical loads under different raft rigidities, a large-scale model test is carried out, which also research the ratio of the force carried by pile and that carried by soil. The research shows that within the range of work load, average pile axial force increases with the increase of the raft rigidity; the axial force of the outer-ring-piles increases while the axial force of inner-ring-piles reduces. The moment of the ring beam and the ribbed beam decrease when the rigidity continues to increase after a certain value, there is little effect on axial force, moment of the ring beam and ribbed beam. With the increase of the stiffness of the beam-slab foundation, the differential settlement of the foundation decreases. However, this trend will become insignificant as the stiffness increases to a certain value. The variety of rigidity of the piled beam-slab foundation could make a difference on the uniformity of subgrade reaction. Besides, there is an optimal stiffness that can make the foundation reaction distribution most uniform. In the experiment, the subgrade reaction distribution of the piled-beam-slab foundation with 12 beams is more uniform comparing to the foundation with 6 piles and block foundation. And there is an optimal rigidity for piled beam-slab foundation, which makes the soil beneath the foundation beared more loads while piles do less. The distribution of piles and beams produces mutual effects on each other. When the distribution of beams changes, the forces of the pile top will be affected. And piles under the beams will also result in beam stress redistribution. In actual project, the rigidity of caps should be optimized and the research results can provide reference for the design of piled beam-slab foundation.

Kriging interpolation methods are widely applied to geological modeling because spatial characteristics of borehole samples are considered by using geostatistics. However, most commonly used Kriging techniques (e.g. the ordinary Kriging method) produce smoothed estimation results, those will lead to an inaccurate regionalization of discontinuous geological stratum around zero value zones, such as pinch-out stratum or stratum with missing segments in some areas. In this paper, a combined indicator-ordinary Kriging method is presented to estimate thicknesses of discontinuous geological stratum. In this method, the estimation of stratum thickness is divided into two steps. Firstly, the indicator Kriging method is used to estimate the distributed area of a geological stratum. Secondly, the ordinary Kriging method is employed to estimate the thicknesses of the geological layer in the distributed area. In addition, a standard error is obtained to evaluate the estimation uncertainty of stratum thickness. The proposed method is applied to estimate the thickness of geological stratum in the Shanghai Yangtze River tunnel project. Through cross validations, the case study shows that the proposed method improves the estimation results by reducing the standard deviation by 15% to 18%, and produces more accurate estimates of thickness of discontinuous geological stratum around zero value zones than that given by the ordinary Kriging method and conventional linear interpolation method.

The first part proposed a two-phase flow-reservoir coupling model, in order to apply this model to evaluate the stability of reservoir and fluid transportation, the commercial algorithm, Comsol Multiphysics, is used and the corresponding numerical modeling method is proposed. The determination procedure of model parameters is firstly presented and the simulation results are validated by the laboratory tests. The density and viscosity of CO2 are determined according to the in situ condition of temperature and pressure, the Van Genuchten parameters of rock layer are from the literature. Based on the triaxial compression tests, effective stress coefficient tests and permeability tests, the model parameters involved in mechanical model and coupling relations are identified. We then perform a case study. The rock layer is situated at depth between 680 to 700 m, and the width is 100 m. The evolution of injection pressure under different injection rates is studied, the distributions of pore pressure, vertical strain and damage variable are presented; the CO2 transportation is also analyzed. The present work offers theoretical basis for evaluating the stability of reservoir and fluid transportation.

Ground subsidence induced by salt cavern gobs under the planned Zhangshu Modern Pharmaceutical Logistic Center determines the feasibility of the project. Mogi model is a ground movement prediction model based on the principle of semi-infinite elasticity, which has been widely used in the modeling of the deformation of volcanoes caused by pressure changes in their magma chambers. With the consideration that the main cause of salt cavern-induced subsidence is the volume shrinkage of caverns, the analytical solution of the salt cavern in steady state creep is introduced to improve the Mogi model and the improved model is used to predict the subsidence of Pharmaceutical Logistic Center. The superposition method is cited to gain the subsidence of the cavern group. The results show that: the ground subsidence and tilt induced by cavern groups are within the scope of building foundation settlement rule, and along with the increase of the distance to cavern groups, the ground tilt firstly increases, and then decreases. What else, the results by Mogi model are in accordance with the numerical simulation. The improved Mogi model provides an accurate and fast method for the ground subsidence analysis of salt cavern groups.

Rock mass integrity is an important indicator for the stability classification of roadway roof, however, the current grading methods just describe from the one-dimensional angle of rock mass structure, which cannot fully reflect the integrity of the roof rock in three-dimensional. In order to overcome the limitation, the stability classification of roadway roof in fractured rock mass is studied by using blockiness as a rock mass integrity index instead of the two sub-indicators of rock mass quality RQD value and joint spacing in the conventional grading method, creating a kind of innovation especially suitable for the fractured rock mass stability classification methods called BT classification methods. According to the block percentage and block volume distribution curve, a solving process of the blockiness of the roadway roof surrounding rock in fractured rock mass is built. An AHP method is applied to determine the weights of the stability factors. The method and the standard of stability classification are constructed. Based on structure surface data and rock mass mechanical parameters of the roadway roof in four fractured rock mass experimental zones in the ore body No. 92 of Tongkeng mine, using the RMR method in the traditional classification methods and the new development method of roadway roof stability classification for each test area, two different classification results are comparatively analyzed, the results show: compared with the traditional RMR classification methods, BT method is more superior to the stability of the description, classification accuracy and safety management guidance, it can more truly and objectively reflect the fractured rock mass roadway roof stability. Research results can provide more reliable scientific basis for the condition of complex fractured rock mass of roadway roof safety classification and management.

In order to study the intensity and the variation law of the airblast induced during the high-speed motion of rock avalanche with multiple angle changes along its travelling path, a true three-dimensional model of the Niujuangou rock avalanche is studied with the software CFD by introducing the definition of resistance along traveling path under the law of Voellmy. The characteristic of the airblast flow field is simulated emphatically with the dynamic mechanism of the airblast discussed based on the back-analysis of the whole travelling process of the Niujuangou rock avalanche. The results show: (1) The whole travelling process of the sliding mass lasts 119 s, and the maximum speed at every moment appears in the part near the front zone of the sliding mass (except t=50 s, the maximum speed appears in the front zone of the sliding mass) with three ultimate values of 52 m/s at 14th second, 55 m/s at 27 th second, and 49 m/s at 50 th second, respectively. (2) The maximum velocity of the airblast appears at the 50th second with its value reaching 38 m/s. The maximum pressure of the airblast, 657 Pa, is generated at the moment the sliding mass bursts out the scarp, which is equivalent to the violent storm. The squeezing effect of the sliding mass on the air ahead is the most obvious when the sliding mass is moving fast and the leading height is higher. (3) The topography along the sliding path displays a large influence on the distribution of airblast pressure. During the high-speed motion of the sliding mass, an obvious gradient variation of air pressure is induced when an obstruction appears along its sliding path, resulting in a destructive effect. When the sliding mass rushes down a scarp or ridge, the velocity of sliding mass will increase rapidly with a negative pressure generated inside of the sliding mass because of weightlessness, meanwhile, a sharply increase of the air pressure will also appear at some locations distributed ahead of the sliding mass due to the intensive compression induced by the sliding mass.

Sanhekou hydraulic junction is one of the two potable water source projects of the water diversion from the Hanjiang River-Weihe River project, and deformation properties of the slope rockmass are the main rock mechanical problem. Thus, many groups of in-situ tests for different lithologies and weathering degree rockmasses are conducted on abutment slope through rigid bearing plate method and borehole deformation test method. At first, 92 points' rigid bearing plate deformation test results are comprehensively analyzed, variation range of the deformation parameters for different rockmasses is obtained; different curve types and influencing factors of test results are emphatically discussed. And then, borehole deformation test method and principle are introduced; borehole deformation test results for abutment slope rockmass are analyzed. At last, deformation test results through two different test methods are contrasted and slope rockmass deformation characteristics are comprehensively studied. The results show that the deformation parameters of this dam abutment slope rockmass are relatively high; deformation curves are mainly belong to linear type; deformation characteristics are closely related to the category; and parameters trend obtained from the two test methods trend to be general consistent.

At present, relatively few drilling surveys have been conducted on coral reefs, and comprehensive geological info on coral reefs is difficult to obtain. However, research on coral reef is of great importance to our development and exploitation of maritime resources. The survey of Chenhang Island in Paracel (Xisha) Islands saw China’s first usage of digital borehole camera technology, which resulted in a large amount of first-hand geological data, but the traditional rock mass integrity index (RMDI) method is not suitable for coral reef rock mass. To evaluate the size effect of cavities on coral reef rock mass, we proposed the concept of coral reef cavity density, and established the coral reef cavity density and block functions. Afterwards, the value of coefficient ? in the RMDI can be determined; the integrity index density function (DIDF) can be reconstructed; and then ultimately the coral reef RMDI can be determined and used to evaluate the coral reef rock mass integrity. The evaluation method is applied to the borehole CK1 of Chenhang Island in Paracel Islands. The evaluation results are generally consistent with other evaluation methods. Some conclusions are drawn as follows. High-resolution borehole images can provide reliable results for evaluation of coral reef rock mass integrity. The cavity density function can reflect the distribution of cavity effects on coral reef rock mass along the axial direction; DIDF is a good representation of coral reef rock mass integrity along the axial direction; The RMDI method is a feasible approach for the evaluation of coral reef rock mass integrity along the full or partial depth of a borehole.

Shield tunneling passing through adjacent large interchange's super-long piles has negative effect on super-long piles and bridge structures. Numerical analysis is conducted to simulate the process of the shield tunneling passing through the adjacent super-long piles. The bearing performance, deformations and forces of super-long piles caused by the shield tunneling with different depths are investigated. Some conclusions are drawn as follows. Large deformations and forces may occur in piles due to nearby tunneling. The various tunneling locations have different influences on the behaviors of piles. The most unfavorable position for lateral displacement is the upper part of pile; the most unfavorable position for longitudinal displacement is the middle part of pile; the most unfavorable position for vertical displacement is the tip of pile; the most unfavorable position for additional axial force is the lower part of pile, when other conditions are the same. The shaft resistances appear ‘S-shaped’ distribution near the tunnel axis; meanwhile, the maximum axial forces of the piles are also located at the tunnel axis. Lateral and longitudinal deformations of piles that extend to bridge decks are considerable. Horizontal deformations of piles top should be strictly controlled while tunneling passing through adjacent interchange's super-long piles.

Major engineering projects put forward higher requirements for rock stability in the process of construction, and a dynamic mode of engineering design is usually applied to deal with various kinds of emergencies and diseases. Rheological damage model can simulate both the time-dependent deformation of rock mass and the time-dependent degradation of mechanical properties, which can reflect the dynamic stability of engineering projects. In order to reflect the instantaneous plastic deformation in the unloading-rebound stage of slope as well as the viscoplastic deformation in the time-evolution stage of slope, loading-plastic and viscoplastic components are applied to the rheology model; thus a composite visco-elastoplastic model (elastic-viscous-viscoelastic- viscoplastic-plastic) is established. Results of compression(unloading) creep test proves the rationality of this model; and rheological parameters are recognized. On this basis, damage tensor describes the characteristics of joint geometry, and damage evolution equation based on the viscoplastic partial strain is established; eventually, a new type of equivalent rheological damage model of jointed rock is established. Applying this model to a soft-hard interbedded slope under the cutting(unloading) condition, the results show that instantaneous plastic damage in unloading-rebound stage and viscoplastic damage in time-evolution stage, of the damageable parts (soft rock section, buried section of soft rock, hard rock section of soft-hard handover), gradually accumulate; the unloading damage areas gradually appear; creep rates of every part gradually increase in varying degrees of growth with the damage accumulating. The reasonable analysis results can reflect the dynamic stability in the process of slope cutting, and guide the intervention time of supporting measures.

High-voltage transit lines, gas and petroleum pipelines, riverbeds and other facilities located in mining disturbed zones are extremely sensitive to surface dynamic movement. Based on the case of coal mining under Jinsha river in Gansu province, in-site surface movement monitoring is carried out; and the dynamic law of surface subsidence of fully mechanized top coal caving mining under the thin alluvium is obtained. The study shows that the surface subsidence experiences a very short initial period and a longer active period of movement. The active period of surface movement appears in the range from 110 m in front of the working face to 400 m back of working face, which lasts 185 days and results in 90.7% of the total surface subsidence. The severe period of surface subsidence occurs at 50 m to 150 m in the rear of working face; but the severer movement time is relatively short about 60 days. Based on the sinking curves of the measuring point displaying S-shaped distribution, and the sinking rate curves that are similar to normal distribution, the dynamic model of surface subsidence and sinking rate are established with respect to the mining time and advancing rate. The trajectories of ground measuring points are captured showing the back and forth moving characteristics. The fractures on the surface induced by mining under thin alluvium intend to develop parallel to the mining direction. With the working face advancing, the time and space features demonstrate that the surface fractures move forward and the concentration areas expand to the outside of the mining area.

All-vertical-piled wharf in offshore deep-water subjects to dynamic load for a long time, such as wave load and impact load, only static analysis cannot meet the requirement of the engineering design. In order to research dynamic simplified calculation method of all-vertical-piled wharf in offshore deep-water, an embedded solid finite element model and the structure and soil interaction 3D elastoplastic finite element model are established by using ABAQUS software. Based on the established finite element model, the natural vibration characteristics of above-mentioned wharf are studied by employing modal analysis method. The analysis indicates that fundamental period of structure is relatively long, and it is close to periods of wave load and impact load; so dynamic response of structure is remarkable. Then the further calculations have shown that the results of dynamic finite element and the theory formula of the dynamic amplification coefficient of single-degree-of-freedom system under wave load and impact load are in good agreement; so dynamic response simplified calculation method of the wharf is put forward. On this basis, the dynamic simplified calculation method is proposed combining with m method, p-y curves method and NL method. In comparison with the dynamic finite element method, the dynamic simplified calculation method is reliable.

Based on the analysis of energy consumption theory, the different reduction coefficients of strength on the cohesion and internal friction angle are assumed; different ways to define the comprehensive slope safety factor is used, and the objective function expression of respective comprehensive safety factor is derived from the principle of virtual work. Using sequential quadratic programming method and interior point method, a nonlinear programming iteration procedure for optimization solution of comprehensive safety factor is established. According to the obtained solution, we investigate the effect of double strength reduction technique evaluation method on the calculation of slope safety factor. The results show that due to many factors affecting the stability of slope, the well-determined function relationship between reduction factor of shear strength parameter c and φ does not exist; the current presupposed processing method that the strength reduction of cohesive force and internal friction angle are under a certain proportion is difficult to give full reasonable explanation. Through the shortest path of strength reduction to define the comprehensive safety factor of the slope is of more clear physical meaning, through which it can deepen engineering technicians’ understanding of strength reduction technology used in slope stability analysis.

By analyzing the effect of groundwater on rock bedded slope, the hydraulic pressure model of rock bedded slope in both cases that the outflow seam is blocked or not are established. Then the slope stability is presented and organized into a dimensionless （Q、P、S）form of expression; curve of relationship between geometric elements and dimensionless variables（Q、P、S）is drawn when the splay fracture in the tailing edge of slope is filled with water, which can bring convenience for analyzing the influence of different geometric elements, water depth, different shear strengths of rock mass on the stability of the slope. By using the relation curve, the effect mechanism of hydraulic pressure on actual bedding rock slope stability is discussed. It is shown that: the effect of hydraulic pressure on slope stability is considerably significant. For example, the safety factor is reduced by 33.33% owing to the effect of hydraulic pressure in the case of the outflow seam unblocked, which is the main external factors triggering the failure of bedding slope；and the safety factor on rock bedded slope in the case of the outflow seam is blocked reduced by about 0.458 than that the outflow seam isn't blocked. The results can provide an important guide to engineering design and construction of rock bedded slope.

The uniaxial compressive strength (UCS) is one of the most basic parameters in geotechnical investigation; it is widely used in the rock foundation design, surrounding rock classification, rock mass classification, rock excavation grading, and rock foundation check and its acceptance. Proximately, 70% of Chongqing urban area is located in the middle Jurassic Shaximiao Formation; so that the UCS has great significance in Shaximiao formation research. From the exploration project practices, this article seeks to establish the relation between the UCS and the softening coefficient of Shaximiao formation rock. An empirical formula has been established between the saturation and natural compressive strength by comparing the calculated values and the large number of experimental values. The results show a high reliability of the calculated values which can replace the experimental values to get a broad application prospects.

Goaf stability is a long-standing problem. But almost all conclusions about goaf-integral-stability-evaluation are on a qualitative level, especially for the goaf in condition of large-scale and complex underground mines. If be quantified, it will, to a better extent, provide some protections for mine safety. For the problem of goaf stability in large-scale, the concept of “failure probability of goaf” based on numerical simulation is introduced to try to answer it. In the postprocessing of FLAC3D, several aspects of failure probability of goaf in the principal stress and shear failure criterion Fs and elastic energy are researched and analyzed respectively, in which the basic principles of probability of statistics are subjected to 95% confidence interval, and "Excel" plugin @Risk is used to statistically analyze the calculation results of grid in FLAC3D; then it makes the stability problem of goaf been quantified. Finally, a conclusion that the principal stresses and elastic energy of rock grid cells in large number follow Weibull distribution and Lognormal distribution has been drawn as well. At the same time, quantification not only solves the problem of the goaf stability, but also makes application of numerical simulation broadened.

Some valuable studies have been done in the aspects of numerical simulation of natural infinite foundation and seismic wave input. The thesis comments the advantages and disadvantages of infinite element, and expatiates on the theory system of ABAQUS infinite element which is improved. The artificial boundary of ABAQUS dynamic infinite element considering the impact of outland fluctuations is proposed. Based on the equivalent boundary force superposition principle, the incident and scattered waves are dealt with separately, and assumed that they are independently to each other. The input ground motion is converted to equivalent stress acting on the interface between the finite element and infinite element to solve the problem of exogenous incident wave. Case study results show that: for the calculation results obtained from inside vibration source and the fixed boundary, the distortion and disturbances appear; the results calculated by the method mentioned above are compared with the results of viscoelastic boundary, which make it certain that the filter function of outgoing scattered wave with the method mentioned above is better than viscoelastic boundary. Therefore, the improved ABAQUS dynamic infinite element boundary method is effective and has certain stability.

Prestressed anchor cable has been widely used as a main reinforcement measure in geotechnical engineering．But the existing calculation method is difficult to reflect the actual situation, such as slip deformation among rock, grout, steel stranded wires. Damage softening concept is introduced by studying characteristics of interface. Damage softening constitutive detailed finite element method is presented to simulate prestressed anchor, and a field test result is compared with calculation result. The most remarkable feature of the algorithm is that it can describe stranded wire, grout, interfaces and other detailed structures. It also can simulate the process of damage softening for interface. The new model can exactly reflect the mechanical change process of the anchoring segment. The test and simulation results are both show that with the load continuous increasing, the interface shear stress peak value of the anchoring segment transfers from the port to inside. The peak value appears at the port when the port is in elastic stage, and the peak value transfers from the port to inside when the port is in damage softening stage. The change law of stress for the anchoring segment of calculation results is basically in accordance with test.

Critical sliding surface search has been an important research topic in the field of slope stability analysis. The limit equilibrium method is still playing a major role in the design of slope because its concept is simple relatively and it is easy to grasp by engineers. Residual thrust method is one of the limit equilibrium methods proposed by Chinese researchers which is practical and has high accuracy in engineering application, and it has been brought into national regulation. But considering the drawbacks that inter-slice force is too crude and only equilibriums of forces are used without regarding to moment equilibriums, we construct a model which satisfies all equilibrium conditions through iteration of Spencer method. And then combining it with ant colony algorithm, we find out the critical slip surface which has the maximal residual thrust. The model has characteristics of high accuracy and fast convergence. Finally, two cases are calculated and compared with the model that has the minimum safety factor based on the ant colony algorithm too. The results indicate the correctness of this method.

The elastic foundation beam method is usually used to analyze the soil-structure interaction. For elastic foundation beams under uniform loads and simple boundary conditions, their theoretical solutions can be obtained from the previous research. Piles under lateral loads and embedded retaining walls are generally analyzed according to the theory of beam on elastic foundation and their coefficients of subgrade reaction are assumed to increase with the increase of the depth. For elastic foundation beams with linearly distributed coefficient of subgrade reaction or with uniform coefficient of subgrade reaction but complex boundary conditions, it is difficult to obtain their theory solutions. In this case, finite difference method or finite element method is used to obtain their approximate solution. When the beam on elastic foundation with linearly distributed coefficient of subgrade reaction is analyzed by finite element method, the calculation accuracy is not ideal if the number of elements are not enough. A 5 times polynomial displacement function and corresponding stiffness matrix of beam element with 2 nodes are presented by adopting weighted residual method. An approximate solution of the deflection of beams under linear distribution of the force is expressed with quintic polynomial. And then more precise nodal displacements and the distribution of element displacements are achieved by the fewer elements. Therefore, the computational efficiency of the presented method is improved. Furthermore, the postprocessing is simplified because the internal force distributions of element can be derived from the displacement function.

Soil’s creep indicates a phenomenon that strain increases with time while keeping soil’s stress stable. Researching soil’s creep properties is very important for confirming soil’s long-term strength; and it is quite popular in recent years. However, a creep experiment costs a lot of time; therefore a simple, feasible and reliable device for soil’s creep properties will boost the research. The soil’s direct shear creep experiment is the simplest and the most intuitive way to research soil’s creep properties. But the experiment just keeps the shearing force stable, in the shearing process, the effective area reduces gradually and the shear stress increases continuously with the shear strain developing, this process is not a proper creep. By adding a simple device on the traditional experiment, the liquid’s buoyancy is used to control the shear stress to keep the shear stress stable in the shearing process. After the corresponding modification of the instrument, we had done a group of contrast tests to check the effect of shear stress controlling. The test results show that it can control the shear stress to a certain level.