The evolution of slope reliability research from statics to even more universal dynamics is an inevitable result of its development. At present, the research on dynamic reliability of slope is in its infancy, and the available evaluation theory and methods are evolved from the static reliability theoretical system of slope. Based on the analysis of the theoretical framework of a reliability problem, the methods of static reliability analysis are divided into six nested modes, four of which are compatible with the dynamic reliability problems. This paper clarifies the significance of the high-performance computing in reliability analysis. A quantitative study of the efficiency of the algorithm is achieved based on the theory of computational complexity. The time complexities of these six modes are proposed under static and dynamic conditions. Based on the statistical analysis of 46 SCI-E citations within 2000-2012, the problems of present slope dynamic reliability research are summarized into three aspects: ① The consideration of uncertainty is inadequate. ② The controversy regarding slope system reliability methods has a significant effect on the dynamic field. ③ Computational efficiency has become one of the technical bottlenecks of restricting the further study of dynamic reliability. Correspondingly, the future development trend can be summarized as follows: ① Consideration of uncertainty will trend to more comprehensive and in-depth methodology. The use of random field theory to characterize the spatial variability of mechanical properties of the rock and soil will gradually be given more serious attention. In addition, the fuzziness and randomness will receive in-depth integration. ② Addressing the controversy issue of slope system reliability methods, a strong proof of theory is desired. In future practice, more precise and more complicated approaches as well as the emerging swarm intelligence optimization algorithms will be widely used. ③ For the issue of computational efficiency for dynamic reliability analysis, the embedded mode that combines response surface method and Monte Carlo simulation method has an excellent prospect of developing. By using the appropriate and excellent algorithms from nonlinear disciplines as a high-efficiency surrogate for the response surface, the development of the slope dynamic reliability research will be greatly promoted.

Strength and failure modes of pre-existing jointed rock mass with different joint dip angles, joint discontinuity degrees, joint sets, load strain ratios, slenderness ratios, joint filling’s depths and its sort under uniaxial compression are studied by means of similar material model tests. The results show that failure modes and peak strength of jointed rock mass are much related to joint configuration. Shear failure along or tensile failure across the joint face will occur in the continuous jointed rock mass, in which the peak strength is less corresponding to the first failure mode. To discontinuous jointed rock mass, its peak strength lies between that of intact rock and continuous jointed rock mass. With increase of parallel joint sets’ number, strength of rock mass gradually decreases. With increase of loading strain ratio, peak strength of rock mass gradually increases; and its failure mode becomes complicated. The slenderness ratio does not change the failure mode of the rock mass; and the intact specimens mainly show tensile failure; while the jointed ones mainly show shear failure. With increase of the slenderness ratio, the peak strength gradually increases; while to joint filling’s depth, it is reverse. The effect of different joint’s fillings on the specimen’s strength exists.

The high liquid limit laterite soil frequently needs to be improved by adding lime or cement due to its moisture susceptible property, while it is used to construct subgrade. However, it’s difficult to uniformly mix ash and soil for the aggregate phenomenon of laterite soil; that would influence on the expected stabilization effects finally. California bearing ratio (CBR) tests are conducted on different sizes aggregation soil specimens of laterite soil and lime stabilized soil. The results show that, the dry density of soil mass increases first and then decreases with the increase of aggregate soil diameter, and the diameter corresponding to the maximum dry density is in 0.2-5 mm range for both laterite soil and lime stabilized soil; and the diameters of laterite soil and lime soil corresponding to the largest CBR values are in 5-10 mm and 2-5 mm range, respectively. The absorption and inflation rate decrease first and then increase with the increasing of aggregate soil size of them. The swelling percent of them are at minimum stage in the diameter range of 2-10 mm. Lime could reduce the expansive of the laterite soil significantly; when the aggregate soil diameter is less than 5 mm. It’s very important to control the size of soil mass strictly in the site construction, so as to ensure the soil strength and moisture don’t fluctuate.

In order to investigate the influence mechanism of effective stress on the adsorption property of coal, a series of isothermal adsorption experiments of coal from Lu’an coal mine are designed and conducted. Combining the porosity and pore size distribution law determined by mercury injection test and using the self-made testing apparatus, the difference of methane adsorption law are confirmed under the different effective stress conditions. The results show that: ①When temperature is constant, CH4 adsorption amount decreases as the effective stress increases; and the larger the gas pressure is the stronger such change tendency becomes. ②The Langmuir equation constant a has a negative correlation with effective stress and the constant b has a positive correlation with effective stress. It is related to the closure of a portion of micropores and the change of chemical potential difference. ③According to the fitting results of experiments, the Langmuir equation takes the influence of effective stress into account is proposed. The research results have some reference significance to the reservoir evaluation and development of coalbed methane.

By analyzing the soil structural parameters based on strain considering and stress considering under confined compression conditions respectively, a unified expression for structural parameters is given, which is soil structural parameters using the secant modulus description. The obvious merit of the soil structural parameters expressed by the secant modulus is that it can avoid, when soil is under initial state, the soil structural parameters based on strain considering and stress considering can not be solved. Further, a single variable model of structural parameters using the active role description is established. In this model, the same stress method and strain method are utilized. For experiment, the confined compression test with intact sample, remolded sample and saturated intact sample from Yangling are conducted. Through the comparison of experimental values and calculation values, the rationality of the single variable model of structural parameters is tested. The results show that the calculated values agree with the experimental values well. The single variable model of structural parameters using the active role description can directly reflect the influence of the active role on soil structure. In addition, the single variable model of structural parameters has the ability to simplify the calculation process and realize the numerical calculation.

At present the prototype monitoring is commonly used to know the seepage in performance period in earth-rock dam. Much research to stable seepage and there is no report about in-situ drilling tests of seepage during the first impoundment. In Pubugou hydropower station，the core-wall is such thin and not decorated with any monitoring instruments at early time above the elevation of 788.00 m. Weak areas of anti-permeability are revealed probably by the earlier monitoring, in-situ drilling tests of seepage is carried out in the core-wall during the first impoundment at 0+131and 0+434 section in August 2010. The results of the test analysis shows that, weak penetration area exists at some elevation of section 0+131and section 0+434 in the core-wall of Pubugou hydropower station. It also shows that under the necessary condition, in situ drilling tests in the core-wall during the first impoundment is practical and meaningful. The anti-permeability of fissured soil under the protection of reversed filter is suggested to be evaluated, the seepage monitoring in core-wall should be strengthened to inspect the safety of the core-wall. The experiment researches provide a reference for other gravel soil core wall of the dam design, construction, and the safety of the operation period.

In order to investigate the effect of bond thickness on the mechanical behavior of idealized bonded granules, based on the previous work in References [1-4], another two kinds of bond thicknesses (i.e. 1.0 and 1.5 mm) between granules are investigated. Then, a series of mechanical tests are performed on the idealized bonded granules with two different bond thicknesses i.e. 1.0 and 1.5 mm, and two different bonding materials, i.e. epoxy resin and Portland cement. The test results show that the effects of bond thickness on the mechanical behaviors of two kinds of bonded granules with different bonding materials are nearly the same, i.e. the peak tension force increases with the increasing of bond thickness, while the peak compression force decreases with the increasing of bond thickness. With the same bond thickness, the peak shear force and rolling resistance increase with the increase of normal force firstly, and then decrease when normal force exceeds a special value. At a given normal force, both the peak shear strength and the rolling resistance will decrease with the increasing of bond thickness. Moreover the strength envelope in the normal-torsion-shear space shrinks almost analogously when the bond thickness changes from 0.6 to 1.5 mm.

3D finite element model is built in this paper, and seismic behavior of pile body of rigid pile composite foundation is studied by using response spectrum method and time history analysis method. According to similarity theory, pile group model of rigid pile composite foundation is established to analyze the response pattern with pseudo-dynamic test methods. And compared and analyzed the results which are obtained by different methods, whether bending moment or shear also are: the biggest is the corner pile, next is the side pile, and the smallest is the center pile; the displacement value difference is very little. The result shows that displacement distribution of rigid pile composite foundation is more uniform under seismic response; rigid pile composite foundation has excellent seismic behavior, based on observing experimental phenomena and studying theoretical and experimental data; pseudo-dynamic test method used to study the seismic behavior of rigid pile composite foundation is feasible; and it can be applied to the other test research of composite foundation with similar seismic behavior.

The rock compressibility has always been the focus of reservoir workers; and the influence of clay characteristics on the rock compressibility gets more attention in recent years. Rock is regarded as two-component model ‘clay + matrix’, based on definition of rock compressibility and theories of elastic mechanics, two-component rock compressibility formula is derived; thus the theoretical relationship between the rock compressibility and content of clay as well as the mechanical properties of clay has been found. Clay-containing sandstone cores from Daniudi gas field are regarded as the research objects, the compressibilities of these cores are measured by triaxial compression experiment with variable internal pressures, the micro-experimental study is carried out simultaneously. Theoretical values of compressibility of these cores are obtained by using the two-component rock compressibility formula as well as the other traditional mathematical methods which do not take clay into consideration. By comparison among the theoretical values of compressibility of different mathematical methods and the measured ones, two-component rock compressibility is proved the closest to the experimental result, which indicates the rationality of theory of two-component rock compressibility, this theory develops a new ideal for predicting the reservoir compressibility.

Interlayer shear weakness zone has a series of features such as loose structure, easy to be softening, large spatial distribution and poor mechanical properties in Baihetan hydropower station. The existence of interlayer shear weakness zone seriously affects the stability of underground cavern groups of hydropower station. In order to reveal and improve the mechanical properties of interlayer shear weakness zone, X-ray diffractometer, scanning electron microscope and mercury intrusion porosimetry tests are applied separately to observe and determine the main mineral composition, the orientated range of particles and the distribution of pore structure in samples. Microstructural properties of interlayer shear weakness zone and its effect on the selection of grouting materials are discussed in detail combining with the testing data. What’s more, chemical modification experiments are carried out based on above experiments. Comparative experiment between samples immersed with or without sodium silicate solution indicates that chemical modification can improve the integrality, elastic wave velocity, compressive strength, elastic modulus and cohesion of interlayer shear weakness zone effectively. These cognitions can provide some useful means for the engineering reinforcement and modification design of interlayer shear weakness zones in Baihetan hydropower station.

Silicifrcation is one of the chemical methods of collapsible loess treatment. For better silicification effect, sodium silicate is modified by various methods. The mechanism of loess reinforced by temperature modified sodium silicate is studied. The physical component such as chemical composition and mineral composition, microstructure are tested and analyzed by carrying out X-ray diffraction (XRD), scanning electron microscope(SEM) and mercury intrusion porosimetry (MIP). The results show that the mechanical strength of loess is improved obviously with the temperature of sodium silicate increasing in the temperature range of 20~80℃. Diffraction intensity of parts of the mineral is reducing in the X-ray diffraction patterns; and low density amorphous phase peak groups appeared. The SEM images show that the gel films increased with the temperature of sodium silicate increasing. MIP data show that surface area of pores increased with the temperature increasing. The findings indicate that the increased amorphous phase and the gel films caused to decreased most probable pore size and increased small pores. The mechanism of loess reinforced by temperature modified sodium silicate is due to reinforcement of the bond strength of cement in microstructure and formation of three-dimensional networks of frame.

As the engineering practice indicated that the rheological behavior is obviously under unloading of the soft clay. According to the typical pit unloading paths, a series of unloading rheological tests were done with stress-control triaxial devices under different unloading conditions. The unloading conditions include confining stress, unloading stress paths and drainage conditions. Through experiments, the unloading rheological deformation of soft clay can be divided into instantaneous rebound deformation and hysteretic rebound deformation. When confining pressure and axial pressure unloaded under the same time, the initial strain rate is relatively larger on a short time after unloading; at the same condition, the hysteretic rebound effect is not obvious because the soil have negative pore pressure. When the axial pressure unloaded, the hysteretic rebound effect is more obvious. At the same unloading path, the rheological properties are more obvious under drainage condition because of that the soil makes water swelling, and the negative pore pressure will eventually be dissipated. Based on the test results, the linear function between the Merchant rheological model parameters and unloading conditions is established; and then established the soft soil unloading rheological empirical model which can consider the effects of the confining pressure and the unloading path. These conclusions are very useful to research the soft clay rheological deformation model and the calculation of excavation unloading rheological deformation.

Experiments on characteristics of infrasonic wave generated by full-regime rock failure under uniaxial loading are carried out with a stiffness material test machine, and the stiffness materials involve granite, limestone, red sandstone, sandstone, phyllite, mudstone. In this study, an advanced digital infrasound emission detecting system to study the characteristics of the infrasonic signals is independently developed. The collected infrasonic signals are processed and analyzed through the wavelet-based denoising method, short-time Fourier transform time-frequency analysis and accumulative ring-down count (ARDC). The results show that: ① The infrasonic wave emission phenomena can apparently appear during the process of uniaxial loading of rocks before rocks fracture. ② The characteristic frequency of prominent infrasonic wave generated by rocks’ fracture typically range 2.0-6.0 Hz. ③ The ARDC of hard rocks, e.g. granite and limestone, are much more than those of soft rocks, e.g. mudstone, in the case of complete structure. Compared with other acoustic signals, infrasound is low-attenuate, cannot be absorbed easily by water and air, and can propagate avoiding huge obstacles due to its long wavelength. Combined with other methods, the further study of the characteristics of infrasonic wave generated by rocks’ microfracture can provide a significant innovate approach and techniques for rock stability monitoring.

Strain energy density factor theory hypothesizes that the crack will propagate in the direction of minimum distortion energy density, while the stress intensity factors which being used in the modified theory are calculated in tension stress field. However, rock mass is usually being in compression in the nature. So the modified strain energy density theory with the stress intensity factors which has been calculated in compression is incorporated, the friction between crack faces also being took into consideration additionally; and a modified strain energy density theory which aims at analyzing the rock crack propagation in compression is proposed. The influence of crack angle, confining pressure and crack surface friction on crack propagation angle are analyzed, and the analyzing results have been compared with experiment results and numerical simulation results of other researchers and a good agreement has been obtained. The analysis shows that the critical load for cracking decreases first and then increases with the increase of crack angle under uniaxial compression. And one crack angle corresponds to more than one crack propagation angle, which means that the crack can propagate in different directions. Finally, the crack propagation angle is related to the confining pressure under triaxial compression. The results can provide reference for numerical simulation of rock crack propagation in compression.

The microstructure changes of Q2 loess in Pucheng power plant, Shaanxi province before and after wetting are studied by using Quanta ESEM (environment scanning electron microscope). A lot of microstructure pictures are obtained. The microstructure qualitative analysis results of Q2 loess before and after wetting with different pressures show that the intra-particle pores are more sensible to pressure and water than inter-particle pores. The maximum pressure of collapsibility of Q2 loess is more than 200 kPa. The area proportion, the roundness, the orientation and the distribution fractal dimension of pore, the gray entropy, the Euler value decrease with increase of pressure and wetting; however, the area proportion, the roundness, the orientation and the distribution fractal dimension of particle increase with pressure and wetting. The quantities of pores with diameter greater than 20 ?m during wetting; while the quantities of pores with diameter less than 20 ?m the pore content increases during wetting. Most pores change during wetting; the large pores turn into medium and small pores; the medium and small pores turn into smaller pores. The peculiar collapsibility of Q2 loess can be explained well by the microstructure changes of Q2 loess before and after wetting with different pressures. The microstructure qualitative analysis provides a new method to research the mechanisms of collapsibility of loess.

In order to confirm the impact of the loading history on the permeability characteristics of broken coal, the permeability characteristics of broken coal with different grain size gradations are tested under two experimental schemes by the CMT5305 electronic universal testing machine with a seepage circuit which is composed of gear pump, reversing valve, overflow valve, permeameter, etc. And the relations between the seepage velocity, permeability, the non-Darcy flow ? factor and the porosity are obtained under the two experimental schemes. The experimental results show: ①The power function fits the relationship between the seepage velocity, permeability and the porosity in the first experimental scheme; and exponential function fits the same relationship in the second scheme. ②When the porosity is large, the permeability and the non-Darcy flow? factor bear a relation to the loading history, while when the porosity is small, they tend to be stable and are independent of the loading history. ③With the decrease of the porosity, the non-Darcy flow ? factor changes from negative to positive in the first scheme; and the permeability characteristics of the broken coal with different grain size gradations are strengthened; but the non-Darcy flow ? factor is always negative in the second scheme and the permeability characteristics are weakened. ④Relation between the non-Darcy flow ? factor and the porosity can be fitted by the cubic polynomial, of which the coefficients have connections with the loading history.

It is an indisputable fact that rainfall can induce landslides in loess area; however, groundwater levels are always very deep in loess area. At present, it is not clear that how does rainfall move in loess and whether it affects groundwater directly when infiltrating ground below. In order to simulate the natural rainfall condition, manual drip experiment is carried out. By using soil moisture meters which are inserted into the wall at a 10 m-deep exploratory well, the changes of moisture content with time of soil layers at different depths in the process of artificial rainfall infiltration could be easily observed; the range affected by rainfall could be confirmed later. The result shows that moisture content of soil layers within 0.5 m changed obviously when the precipitation is 3.82 mm/d (light rain), while that of below have almost no changes; the moisture content within 1 m increases when the precipitation is 10.31 mm/d (moderate rain); the moisture content of the layers within 1 m increases significantly, and that of between 1 m to 1.6 m have a slight rise when the precipitation reached 25.21 mm/d (heavy rain), the changes of moisture content lag and the growth decreases gradually with depth. It is shown that if there are no obvious water paths in arid loess region, the infiltration depth of short-term rainfall is limited and it is difficult to reach the groundwater level, but according to the results of paleosol in deeper, the moisture content of paleosol has a considerable increase even though that of upper loess is relatively weak, which indicates that unsaturated seepage or vapor migration do exist in loess. It is also found that the circulation of soil moisture is primarily occurred in evaporation zone; that within shallow 0.7 m in Longdong Loess Plateau, if there is no recharge from follow-up rainfall, the rainfall infiltrated within evaporation zone will be excreted upward by evaporation; however, it will continue to move downward without the influence of evaporation when infiltrating beyond the evaporation zone; the water will gather on the surface as encountering the impervious layer, which is also reflected preferably by finite element simulation.

The tailings sample has characteristics of easily to be disturbed in the process of both transportation and storage. However, limited by human resources as well as project budget, or else factors, it is impossible to establish field laboratory for all upstream tailings dam during their engineering geological exploration, thereby leading to errors between the shear strength index and practical situation. For this reason, an extensive field testing is carried out in a lead-zinc mine tailings dam, the water content and standard penetration number can be easily obtained from field testing; and the internal friction angles of tailings as it changes through standard penetration number under the influence of the water content are studied. Considering the effect of overburden pressure, a amended expressions of standard penetration number is proposed. And using the standard penetration number，a estimation method about the internal friction angle of tailings is deduced; Finally, several examples are given to verify that except for the situation when the amended standard penetration number is N1 >8（5%< <20%），this method can estimate the internal friction angle of tailings sand effectively. The results show that, the method has a high application value in upstream tailings dams’ engineering geological exploration in the future.

In order to get the seismic permanent displacement of clay slope reinforced with cantilever stabilizing piles effectively, based on the upper bound theorem of limit analysis and circular failure mode of soil slope, factor of safety and the corresponding yield acceleration of slope with stabilizing piles under the earthquake can be derived through calculating the rate of work done by external loads and the energy dissipation rate. Then, combined with the Newmark’s sliding block method, the expression for the seismic permanent displacement related to design safety factor can be deducted by the double integrals of the rotational acceleration of slope. The paper takes a clay slope reinforced with cantilever stabilizing piles under the 5.12 Wenchuan Earthquake for example, the validity of the proposed method is verified by comparison with Ambraseys’s method. In Addition, the permanent displacement time history of the reinforced slope is given, and the relationship between the permanent displacement and factor of safety of the slope is also shown. The laws that the permanent displacement affected by the cohesion and internal friction angle of soil under different safety conditions are obtained. The research results show that the permanent displacement exponentially decreases with design safety factor of the slope increasing. In the case of lower design safety factor, the permanent displacement is more sensitive to soil shear strength parameters. However, the sensitivity is gradually reduced with the increase of the design safety factor.

Based on the Barton-Bandis failure criterion, this paper explores two common methods on converting the nonlinear strength parameters of Barton-Bandis failure criterion into the linear shear strength parameters c, φ of Mohr-Coulomb failure criterion, and discusses their advantages and disadvantages by case study. Following this idea, the anti-sliding stability factor was deduced for such a plane slide rock slope, which was reinforced by prestressed anchor cable and controlled by single rock joint. Next, the analysis of parameters on anchoring was conducted. Parametric analysis shows that, studying the anti-sliding stability factor of plane slide rock slope by Barton-Bandis failure criterion is intuitive and effective, in comparison with obtaining the Mohr-Coulomb shear strength parameters with the equivalent linear fitting or tangent equivalent method. Meanwhile, the slope safety factor increases significantly with the increase of three factors, namely, the basic friction angle, the surface roughness coefficient and the effective compressive strength. Also, the influence of the basic friction angle and the roughness coefficient on the slope safety factor is more pronounced. It is also shown that the larger the tension force of anchor cable is, the better the slope sliding stability will be, whilst, the value of the set angle of anchor cable exerts a negative role on the slope sliding stability; therefore, the improper dip angle of anchor cables will significantly reduces the anchorage effect.

Under the intense rainfall infiltration, the air in the shallow slope is likely to be confined, and the pore air pressure in air-confining condition increases constantly as the infiltration of rainfall. The physical meaning of the air-closing pressure is illustrated through the force analysis of the wetting front. Compared with the classical Green-Ampt infiltration model, the simplified infiltration model considering the air pressure is used to study the effects of air pressure on the infiltration rate and the moving wetting front. Then the infiltration process and stability analysis of a large area of shallow slope with bedrock beneath is studied through the simplified infiltration model. The results show that the air pressure in the air-confining condition reduces the infiltration rate and the safety factor remarkably, which could also reveal the reason that why some areas had frequent landslides after the rainfall. So considering air pressure for landslide forecasting is greatly significant.

In order to study the development of soil arching in the piled embankment, a series of three-dimensional model tests are conducted. The relationships between stress reduction ratio and ground settlement with different pile cap sizes and different geosynthetic reinforcement materials are analyzed in detail. Based on the test results, it is shown that the effect of soil arching develops gradually with differential settlement and it is more significant at large differential settlement. The inclusion of geosynthetic reinforcements reduces the differential settlement and weakens the soil arching effect correspondingly; and the load transfer from soil to pile top is caused by the combination of soil arching effect and tension membrane effect. The finite element sensitivity analyses are also carried out to study the effects of pile spacing, embankment height and other factors which did not included in the model tests. The focus of numerical analysis are laid on the development process of the soil arching effect and an index is proposed to describe the mobilized degree of the soil arching. Based on the test data, the results of the finite element analyses, and the experimental data collected from literature, a hyperbola equation is suggested to describe the relationship between the mobilized degree of the soil arching and the normalized deformation. The given equation can be used to account the development of soil arching with settlement.

Collapse is one of the typical common geological hazards during the construction of shallow tunnels. Real-time control conducted using dynamic evaluation model and risk aversion is an effective way to ensure the safety of tunnel construction and can be fallen into the following procedures: ①Based on the geological conditions in and out of the tunnel, the risk factors of collapse are analyzed and a fuzzy analytic hierarchy process (FAHP) model of risk assessment for tunnel collapse is proposed. Static evaluation of collapse is then conducted using the risk environment and the proposed model. ②The risk environment is updated based on the actual geological conditions. Furthermore, dynamic evaluation is carried out according to the risk environment, meteoric water, excavation method, support measures and monitoring measurement. ③A risk aversion method is proposed using the results of dynamic evaluation. The purpose of risk reduction can be realized through the optimization of construction scheme. The presented approach has been successfully applied to the construction of Duanjiawu tunnel to avoid collapse, which can provide references to the risk assessment of other similar engineering cases.

The monitored sections are always assembled behind working face excavation. The displacement induced during this period is called loss displacement. The optimization back analysis method is used to get loss displacement. The method transforms the problem to a global optimized problem that treats the error between geodesic loss displacement and computational loss displacement as objective function, the mechanical parameters of surrounding rocks as decision variables. Aiming to solve the global optimized problem that is high nonlinearity, many peak values and expensive cost, an intelligent cooperative optimization algorithm based on particle swarm optimization (PSO) and Gaussian process (GP) machine learning for back analysis is proposed, then combined the FLAC3D, a new method called PSO-GP-FLAC3D for the loss displacement back analysis is developed. The results of a numerical example show that the proposed method is feasible. It not only obtains reliably predicted loss displacement, but also gets reasonable mechanical parameters of surrounding rocks. In addition, the proposed method has the merits of global optimization and high computational efficiency. It can overcome the shortcomings that the traditional optimization back analysis method is easy to fall into local optimum or overly dependent on initial learning samples. The proposed method is applied to the auxiliary tunnel BK14+599 section of Jinping Ⅱ hydropower station in China, and loss displacement and mechanical parameters of surrounding rocks are obtained. The results indicate that the elastic deformation of surrounding rocks increased quickly after excavation, which results in large loss displacement. Therefore, the loss displacement of surrounding rocks can not be ignored in stability evaluation or back analysis for underground engineering, especially for deep underground rock engineering.

Besides elastic strain, creep would also occurred in long-term pile stress test represented by pile immersion test in loess regions for concrete pile; and the influence of creep occurred under long-term axial stress was usually be overlooked in the past when calculating stress of pile body. But creep is a real existence, influence degree of creep and how to eliminate its effect are worth studying. Based on comparative analysis of field test data, how the concrete creep affect the analytical results of pile stress is studied; and the conclusion shows that the overlook of concrete creep will lead to wrong distribution rules of axis force and friction. A formula, which calculates axial force of pile and can eliminate the creep influence, is derived from some basic theory on creep. Some measures needing be taken in pile immersion test of loess regions to attain representative creep curve are presented; mainly include: controlling the concrete strength grade of test pile, setting calibration section near pile top and keeping concrete’s temperature and moisture constant in this section and are in the same with lower pile.

In light of the problems of that the highway rock slopes have large numbers and slope stability is hardly to predict in time, the stress monitoring method of the anchoring rock bolt is used to evaluate slope stability. Typical slope along Guangyuan- Shaanchuan expressway reconstruction as the example, the FLAC3D software is taken to simulate the excavating and support process of the rock slope, and the strength reduction method is taken to analyze the change of rock bolt axial force during the rock mass strength reduction process, the monitoring values are obtained; and combined with the result of field test to evaluate the slope stability. The research results show that the mainly monitoring locations should be at mudstone structures, and the stress monitoring is a wholly system; so that the early warning should be made if axial force values at any locations reached the early warning values; The result of field test shows that the stress monitoring has obvious change at 120 d, while the displacement change has a time lag, it appear obvious change at 167 d; from the results of stress monitoring and displacement monitoring, a conclusion is drawn that the slope keep in a state of safety operation, so the proposed stress monitoring method can be applied to evaluate the highway rock slope stability.

In order to estimate seismic surface rupture dislocation more accurately, the finite element method of pseudo-static elastoplasticity is used for numerical simulation to seismic surface rupture by strike-slip fault. In the numerical model, the two cases of silty clay and clay are discussed respectively. According to the relationship between magnitude M and bedrock dislocation Dbedrock which is regressed and fitted based on historical earthquake damage data and numerical calculation results, the relationship between magnitude M and surface dislocation Dsurface is set up. In the formula, the influence factor of soil thickness H is considered, and not just estimate surface rupture dislocation depending on magnitude by using statistical formula. The results show that: seismic surface rupture dislocation under strike-slip fault relates not only to magnitude, but to soil thickness and soil properties; Surface dislocation decreases gradually with the increasing of soil thickness under the same magnitude; Surface dislocation of silty clay is larger than that of clay under the same magnitude and soil thickness; The critical value of soil thickness without considering strike-slip fault is estimated based on the fitting formulas, and the result is helpful to improve the reliability of seismic risk evaluation of active fault.

In view of the difference in the monotonicity for risk factors and the nonlinear relationship between the primary risk factors and secondary risk factors in the evaluation of debris flow risk, a new method to evaluate the correlation between the primary risk factors and secondary risk factors by using scatter diagrams and Spearman rank correlation is proposed. In the method, the scatter diagrams are used to analyze the relationship between the primary risk factors and the secondary risk factors, and on this basis, a preliminary screening of the secondary risk factors can be made. Spearman coefficients of rank correlations are used to further screen the secondary risk factors and identify their weights. With the new method, a new formula of debris flow risk is established by using the basic data of 37 debris flow gullies in Yunnan province. Finally, the new formula is taken to calculate the debris flow risk of 12 debris flow gullies in Dongchuan city. The results verify that the source conditions and dynamic conditions are significant to the potential risk of debris flows, so as to justify the rationality of this method.

In the project of deep excavation pit supported by piles with prestressed anchors, the soil pressures acting on the pile and pile body displacement are nonlinearly changed. For the nonlinear change issue, based on displacement soil pressure model, considering the influence of the displacement of supporting structure, a calculation formula of mixing method is derived. The mixing method can effectively track the deformation process of supporting structure, and reflect the nonlinear function relationship between soil and the pile. Combining with the engineering practice, the MATLAB program is compiled; the nonlinear relationship between earth pressure and pile body displacement is well reflected by the calculation results; the calculated results are analytically compared with Lizheng software. It is shown that they can anastomose each other well so as to prove that, this calculation method has wide applicability and a good reference value for deep excavation pit supporting structure design.

The mechanism of foundation pit excavation affecting the below existing shield tunnel is researched. 14 cases of the foundation pit instance are collected to make a statistical analysis of measured data. The results show that the maximum vertical displacements of shield tunnel are all uplift, and 64% of the tunnel uplift values exceed the alarm value (10 mm). Based on the measured statistical data, an empirical tunnel maximum uplift value prediction formula below pit is proposed. Measured data of displacements in horizontal direction are fewer surveyed; and they are also small; the convergent small deformations change from “horizontal stretching, vertical compression” to the “horizontal compression, vertical stretching”. Based on the at Hangzhou Yan’an Road, underground street passage project, the influence of foundation pit excavation on lower shield tunnel deformation in Hangzhou Metro Line 1 is researched. The measured data of tunnel vertical displacements, horizontal displacements and horizontal convergence deformations are analyzed. The results verify the reliability of theoretical analysis and the proposed formula.

Reamers have been the major implements used to enlarge the hole size in reaming stage of horizontal directional drilling (HDD). The choice of its available structural design becomes critical to maximize the rate of penetration and minimize the tripping time; thereby decreasing the cost of operations and the risk of experiencing stability problems. Moreover, because the duration period of a HDD project is largely dependant on the reaming stage; it is crucial to study the reaming efficiency by use of the appropriate operating conditions (cutting angle and depth). The reaming efficiency of reamer is analyzed based on the development of a 3D analytical cutting force model of soil orthogonal cutting under a single reamer cutter. Focusing on the soil orthogonal cutting mechanism under a single reamer cutter, the interaction and friction between soil and cutter and the shear action of 3D shear zone are comprehensively considered, consequently the mechanical properties are given. Based on these analyses and using the Drucker-Prager criterion given a weight to the intermediate principal stress, the analytical models are proposed. In addition, this paper presents 3D FEM simulations for the analysis of soil orthogonal cutting under a single reamer cutter. The subject has been covered in two parts. Part one deals with the verification of the analytical cutting force model, the other focuses on the assessment and selection of the criterions of shear angle. The analytical cutting force model presented provides the capability to evaluate cutter loading for utilization of a single cutter with different rake angles to cut soils, and to plot the effect of change in the rake angle. Finally, the optimum rake angle of single reamer cutter was obtained. The results of this analysis can be integrated to study reamer performance. It can also provide a guideline to the application and design of the reamer assembly for various soils.

Sandy pebble soil is a granular media, and the physico-mechanical properties of sandy pebble soil are different from those of sandy soil and intact rock mass. Here sandy pebble soil is considered as a simplified material, namely a two-phase composite material consists of sandy soil as matrix and pebble as ellipsoid inclusion. This paper presents the theoretical derivation of equivalent elastic matrix calculation equation. The derivation process is based on Eshelby tensors and Mori-Tanaka equivalent method within small deformation condition. The process is also considered pebble’s content and distribution, using replacement iterative method. This paper focuses on the calculation of sandy pebble soil equivalent elastic modulus using numerical solution through compile program. Comparison is made between numerical solution and theoretical result. The result shows that the theoretical calculation method has better calculation accuracy than the earlier calculation methods of previous experiment and theory. When the pebble volume fraction less than 50%, the result of theoretical calculation coincides with experiment result, thus the presented method can be used to predict sandy pebble soil’s macroscopic mechanical properties, and it is beneficial to underground engineering application; when the volume fraction more than 50%, the theoretical calculation result may have some error with the experiment result.

To prevent the accident of fleeing bore during manual digging pile construction, the instability mechanism of soil between manual digging piles is discussed; then the feature of displacement in instability is analyzed; a stability analysis mechanical model is established; formulas for the stability coefficient and critical value of pile spacing are derived; and some suggestions for fleeing bore prevention are provided. The results show that during the instability of soil between piles, the sliding soil displacement parallels to the line through the two pile centers and its width is equal to minimum of diameters of the two piles. While the most disadvantageous value of the thickness of the sliding soil could be determined by repeated calculation, the stability coefficient of soil between piles is inversely proportional to the width and the depth of the sliding soil, is proportional to the pile spacing, and rises with increasing of the shear strength and residual shear strength of the sliding soil. Controlling the concrete height difference between two pile holes, increasing the pile spacing, strengthening the lining structures, and reducing disturbance of soil between piles, are the most effective measures for fleeing bore prevention. Engineering practice has proved that the stability analysis method of soil between manual digging piles is reasonable and practical; so as to provide reference for manual digging pile construction in cohesive soil-based site.

Shield is a kind of underground construction machinery used to excavate soil tunnel with efficiency, environmental protection, safety and high quality, and it is employed widely in city metro construction in China. The origin driving of shield is one of the key techniques in shield construction. Through analyzing normal and origin driving shields, the mechanical model of shield driving in the two driving modes is established with reference to fundamental principles of soil mechanics. The calculation formula for resistance moment of the shield is presented, and the composition and effects of resistance moment of normal driving mode of shield are analyzed. It is discovered that in the normal driving mode, the resistance moment from the cave wall is strong enough to countervail the reverse torque resulted from the shield chisels’ cutting rock, and during the origin driving, protective measures should be taken in between shield cushion and its crust to prevent torsion. The formula has been adopted in some earth pressure balance (EPB) shield tunneling construction project with good results achieved. Conclusions can be referenced for the design and application of EPB shield.

Tensile crack induced by differential settlement is the primary cause and typical form in earth-rock dam failure. The classical deformation gradient method is extended by coupling with finite element method. The newly developed deformation gradient finite element method is used to calculate deformation gradient with deformation obtained by conventional FEM instead of on-site monitoring data. This method is simple, and can be used to estimate the risk of tensile cracking in the design phase of dam construction. The possibility of tensile cracking caused by post deformation in Nuozhadu high earth core rockfill dam is analyzed with the method proposed. The distribution rules of deformation gradient and its relation with post deformation are discussed. The analytical results show that: in Nuozhadu high earth core rockfill dam, the post settlement at dam crest is smaller than 0.39 percent of the dam height; so that tensile cracking is almost impossible. According to the case study, the proposed method is applicable to cracking analysis of high earth-rock dam.

According to the practice of the excavation of the Xiqing Road Tunnel adjacent to the existing tunnel of the operating Tianjin Metro Line 1, ABAQUS is applied to simulate dynamically the construction process based on the field monitoring data. On this basis, the effects and the effectiveness of the soil reinforcement alongside the existing tunnel, a protection hoop formed by the slab and anti-floating piles and the reverse heap-loading on the track deformation of the existing tunnel are analyzed. It is found out that the above protection measures adopted synthetically can timely and effectively control the uplift of the track in the existing tunnel and ensure the safe operation of metro. Furthermore, the effect law of the different reinforcement parameters on the track deformation of the existing tunnel are studied. The results show that the increase in the different reinforcement parameters can reduce the up lift of the track in the tunnel and the different deformations between the two adjacent boxes of deformation joint, but the reinforcement effect decreases with increase of the parameters; and there exists a reasonable scope of the reinforcement. The results can provide evidence for the optimization of the construction design.

Based on triaxial compressive experiments of hard rock simulated by numerical method, the influence of intermediate principal stress on the fracturing mechanism of homogeneous and heterogeneous rocks is analyzed with four constitutive models, i.e. Mohr-Coulomb, Drucker-Prager and strain-softening considering deformation modulus degradation or not. The results show that the intermediate principal stress has a larger effect on the strength of rock using Drucker-Prager model than that using other models, whether the rock is homogeneous or heterogeneous. And it has a large impact on the failure process and mode of heterogeneous rock using strain-softening model. For the example in this paper, the strength of homogeneous or heterogeneous rock varies considerably with different constitutive models. Although the rock uses the same constitutive model, the strength of homogeneous rock is much larger than that of heterogeneous rock except for Drucker-Prager model. Because the responses of engineering rock masses to the intermediate principal stress are different, proper constitutive model should be chosen based on the characteristics of rock masses in order to guarantee engineering safety during the design process of underground structure.

Dynamic compaction (DC) plus drainage is a new technology developed in recent years, especially in improving the hydraulic fill deposits. Based on the analysis of energy dissipation, soil compaction mechanism and the model of pore water pressure generated by impact loading, a simple but effective model is developed to simulate the process of dynamic compaction. A numerical program based on the finite difference method is developed to solve the boundary value problem under the condition of DC plus drainage. Development of pore pressure and the performances of compaction during DC are studied by the numerical results and compared with field data. Some factors affecting the performances of compaction such as hydraulic conductivity, time between impacts and distance of wick drains are discussed. Different effects between number of drops and impact energy per drop are also analyzed. The simulation results indicate that the proposed numerical model can simulate the process of DC with drainage. The development of excess pore water pressure and the reinforcement effect of soil can be predicted correctly. The drainage structure introduced in the DC technique can reinforce the deep soil and shorten the construction period. Finally, a design procedure is proposed to improve the practicality of DC and drainage technique.

Based on the theory of subcritical expansion of cracks, rockfill particles breakage with the time-dependent effect is caused by the extension of microcracks. Through a new way to simulate the rheological behavior of rockfill, a series of numerical uniaxial rheological tests are carried out by the three-dimensional particle flow code method, according to the theory of subcritical expansion of cracks. The simulation results are partially compared with the lab experiments, and good agreement has been achieved. The evolution of microscopic characteristics for rockfill samples and particles breakage are presented visually during the process of numerical rheology. The analytical results show that rheology is the main results of the delayed particles breakage caused by the extension of microscopic crack, which further develops the recognition of the rheological mechanism of rockfill.

Based on the specialty of loading environment for the deep underground structure, a reasonable boundary condition setting method is developed to the coupled static and dynamic response analysis of deep structure. The system of forces on the boundaries of computational region is determined and used to match the inner initial earth stresses; and then the system of forces is transformed to that of dynamic forces in the form of step function. Finally, this system of dynamic forces and subsequent dynamic loading act together. Research results show that the reasonable results can be gotten through indispensable transform of boundary condition during a complete coupled static and dynamic analysis. In addition, the coupled static and dynamic response analysis can be done well with the artificial viscous boundary condition in software simply. The case studies indicate that the boundary condition setting method has many advantages such as good accuracy, efficiency and convenience.

Great variability of lithology and permeability, low porosity, poor connectivity, complex pore structure and serious heterogeneity are the common characteristics of glutenite reservoir. Therefore it is difficult to control crack propagation form of hydraulic fractures, and undertake a large-scale reconstruction. Based on the characteristics of a typical glutenite reservoir in China, the propagating mechanism of hydraulic fractures is investigated by using numerical method. Numerical simulation results show that the hydraulic fracturing is more complex due to the existing of gravels and there are four fracturing modes: terminations, deflections, penetrations and attractions. The primary fractures are strictly dependent on the difference of the maximum and minimum stress. With the increasing of principal stress difference, fractures are selected to cut through gravels rather than propagate around gravels. Consequently the propagation of primary fractures appears discrepancy and a lower breakdown pressure is needed. The higher the gravel volume content is, the worse the heterogeneity is. With the increasing of gravel volume content, the interaction between gravels and fractures is more evident. The higher gravel volume content needs a higher breakdown pressure. For the cases with a constant gravel volume content, the fracture initiation is mainly influenced by the stochastic distributing of gravels, consequently a gently higher breakdown pressure is required for the larger gravels.

The shearing induced dilatancy is an important deformation characteristic of granular materials during loading process. As the minimal unit to remain stable under external load, void cell is used to characterize the internal structure of granular materials. Based on the shear process of the individual void cell, it is found that the volume change of void cell is dependent on the stress ratio and the shape of void cell. It is explained the microscopic mechanism of the phenomenon that the dense granular materials compress first and then dilate. The evolutions of the shape of the individual void cell and volume deformation in them during biaxial shear test are simulated by using discrete element method (DEM). The results show that, the void cell is enlarged along the direction of the maximum principal stress and the volume deformation in the void cell compression first and then dilate as biaxial compression proceeds. Moreover, localization phenomenon is observed in the volume deformation in local void cells from the numerical results, i.e. voids with large dilatancy exhibit in the form of oblique bands at large deformation stage. The mechanical analysis of individual void cells and DEM results of dense granular array show that dilatancy of granular materials is dependent on the microscopic geometry fabric and the transmission of the force in them.

In order to study the mechanism of high pressure water jetting on the coal, the damage mechanism of high pressure water jetting on the coal is investigated by using numerical simulation, which is based on coal using J-H-C damage constitutive model and water jet using Bridgman equation. Based on fluid-solid coupling penalty function, a mode of numerical algorithm, the various damage forms of the coal are gained under different jetting pressures of water. The numerical calculated values are in good agreement with experimental results. The numerical simulation results show that, different water pressures of jet flow cause different damage patterns in coal. The shape of damage caused by jetting in the coal is staged and the recombination action of compression stress wave and tensile stress wave is the main factor that results in coal damage. With penetration evolving, compression zone and tensile zone reduce that are formed by high water. There is the critical breakdown pressure of water on the coal that has different fracture strength.