Through a lot of tests under triaxial stress, rock salt dissolving characteristics have been studied. The results show that the influence of triaxial stress on rock salt dissolving velocity can not be ignored; the relationships between macro dissolving velocity (can be equal to dissolved mass in tests) and confining pressure, plastic volumetric strain and dissolving time, can be used to quantitatively describe the variation of rock salt dissolving velocity under the effect of triaxial stress according to the test data; the numerical expressions between macro dissolving velocity and confining pressure, plastic volumetric strain and dissolving time, are obtained; at the same dissolving time and plastic volumetric strain condition, under the different confining pressures, the obvious difference between the shape of rock salt sample before and after dissolved exists; dissolved mass with stress effect changes greatly, and with increased confining pressure, dissolved mass with stress effect on the variation for the shape decreases; the obtained mechanism of rock salt dissolving characteristics under triaxial stress is that the direct relationship between rock salt dissolving velocity under triaxial stress and development of surface cracks under different confining pressures is obtained. The achieved results can provide a foundation for the further analyses of coupled stress-dissolving mechanism of rock salt.

By laboratory test, the potential use and effectiveness of soda residue as an additive for improving expansive soil are evaluated. The tests research the features of the basic physico-mechanical properties and expansibility of soda residues treated soil. The result shows that the increase of blending residue ratio has made the viscous composition decreased while the percentage of coarse granule increases so that the plasticity index, liquid limit, relative density, free swell index, load swell index are reduced significantly with the increase of soda residue. The test indicates that the soda residue has significant impact on the improvement of the expansibility of expansive soil. The range of compaction water content for soda residues treated soil is larger than expansive soil’s. It brings great convenience for the construction of soda residues treated soil roadbed. After 7 days conservation, there is a remarkable increase in unconfined compression strength and shear strength. Furthermore, a peak appears when the blending ratio of residue has come up to 30%. The remarkable increase in cohesion reflects the shear strength enhancement. However, the angle of internal friction changes little.

The fatigue damage characteristic of salt rock is researched based on the acoustic emission (AE) technology by changing the upper limit stress, lower limit stress and loading rate. It is found that the AE count increases slowly with the stress increasing, but for sandstone, the AE count is intensive around the upper limit stress. The fatigue life of salt rock is more dependent on lower limit stress than sandstone. The higher the upper limit stress is, the more the AE count is, and the higher the loading rate is, the damage becomes much earlier. It is found that the AE cumulative curves are in keeping with strain curves which show that they can both show the fatigue damage process of salt rock. In the end, the constant amplitude load is instead by three-level variable amplitude load. The AE count becomes much more in the third level which shows that the variable amplitude load makes more serious fatigue damage in the salt rock than the constant amplitude load does.

The uniaxial loading tests on cement-soil are conducted by true triaxial apparatus in order to study the characteristics of cement-soil anisotropic deformation and the effect of stress on the lateral expansions. It is shown that the specimen is compressed along with the loading direction and the lateral expansions are related to the shear stress increment under uniaxial loading condition. Under the loading condition in the direction of maximum principal stress, the value of the shear stress increment is greater than zero, and the lateral expansions in two directions of intermediate principal stress and minor principal stress are shown; under the loading condition in the direction of intermediate principal stress, the lateral expansions in the directions of minor principal stress are shown when the value of the shear stress increment is greater than zero only; under the loading condition in the direction of minor principal stress, lateral expansions are not produced due to the value of the shear stress increment is less than zero; both the lateral expansions and compressive strain decrease with the increasing of consolidation stress for the same stress increment. It can be seen that the lateral expansions have a negative correlation with the constraining force at a certain direction according to the energy analysis.

Using large-scale shearing device, K0 consolidated-drained triaxial test and isotropically consolidated-drained triaxial test under different confining pressures are performed for three relative density overburden material of Shuangjiangkou earth dam. The behaviour of coarse-grained soil under K0-consolidation is investigated. The test results from K0 consolidated-drained tests are compared with those from isotropically consolidated-drained tests. The results show that the relationship between mean principal stress and volumetric strain and between deviatoric stress and deviatoric strain during the K0-consolidation can be fitted with power function. In the stage with steady pressure after K0-consolidation, the strain-time curve can be fitted with exponential function. The strength of K0 consolidated-drained triaxial shear test is slight greater than that of isotropically consolidated-drained test. The initial elastic modulus Ei and Poisson’s ratio vi obtained from K0 consolidated-drained triaxial test is larger than that from isotropically consolidated-drained test. The dilatancy K0-consolidated sample is more evident.

In order to investigate compression mechanical properties with strain rates varying from 600 s－1 to 2 500 s－1 on compacted clays under different compaction degrees and water contents，the specimens are subjected to axial impact with different projectile speeds by using the split Hopkinson pressure bar(SHPB) of 25 mm in diameter made by polycarbonate and a small pellet of vacuum seal cement as pulse shaper; and the validity of experiment is discussed considering the stress equilibrium and constant strain rate. The related curves of stress and strain, the relationship between dynamic stress and strain at peak with strain rates, the relationship between dynamic stress increase factor and strain increase factor at peak with strain rates, and what’more, the relationship between specific energy absorption and strain rates are also analyzed. Experimental results show that the dynamic peak stress, peak strain and specific energy absorption increase with the increase of strain rate; but the compaction degrees and the water contents have no influence on them; compaction degrees and water contents have a greater influence on dynamic stress increase factor and strain increase factor at peak; specific energy absorptions are dependent on strain rates; and the strain rate effect can be expressed by exponential approximations.

To study the rock joint parameters, joint space and joint angle of rock fragmentation by full face rock tunnel boring machine (TBM) disc cutter, the test of high-strength gypsum specimen penetrated by wedge indentation is applied. Data of penetration depth and loads during the loading process are collected. Shooting with the camera in real time, photograph of the specimen surface damage and failure mode of the development process are taken. The results show that: when joint angle is constant, a greater joint space needs a greater penetration load when loading value drops, it also needs greater penetration power and crack propagation energy; when joint angle equals to 0 and 90, anti-invasive factor is consistent. When the joint angle equals to 30 and 60, with the increase of joint space, anti-invasive factor increases. When the joint spacing is constant, with the increase of the angle, the peak load, penetration power and crack propagation energy decrease and then increase. When joint angle equals to 30, the values are the minimum. According to a morphological analysis after the destruction of specimens, it is found that the spatial characteristics of joints crack obviously control the crack mode and have significant limitations for the damage region .

The influence of crack filling on the mechanical property of jointed rock mass is studied. The brittle jointed rock mass specimens with preset crack are simulated by the similar material. The mechanical properties of specimens are tested by uniaxial compression. The fracture and damage of jointed rock mass are analyzed through the program ABAQUS. The tests and analyses results show that compared with the specimens that there are no filling in the crack, the peak strength of jointed rock specimens which have filled crack slightly increase and its post-peak plasticity is enhanced significantly; the strain energy release rate Gc of jointed rock specimen decreases. The damage factor and the hoop tension stress field area as well as peak are less than those of specimens with non-filled cracks.

According to the situation of CHINALCO Henan Branch, combined with ore discharge mechanics theory, similarity experiment and discrete element simulation technology, we deeply research discharge mechanism and main factors that influence ore flow in hopper in both macro and micro conditions. Discrete element simulation shows the dynamic process of mutual interaction between particles-particles, particles-walls. According to the results, we design a new internal vertical flow-aiding device, achieve a better effect in field experiment. New device not only greatly improves the flow capability of ore in hopper, solves the blocking, arching, stucking problems which troubled CHINALCO for several decades, optimizes the mechanical relationship between ore and hopper, reduces wall dynamic contact pressure, but also largely improves the discharge efficiency and safety factor and reduces the labor intensity.

To get a better understanding of relaxation process of warm permafrost and find factors influencing on this process, a series of laboratory triaxial relaxation tests are conducted. The results indicate that the instantaneous relaxation increases with pre-strain and the relaxation stabilization duration prolongs. For the constant strain rate loading, the increase in strain rate leads to bigger relaxation rate and longer stabilization duration. For constant stress rate loading, the stress rate iucreases, the stabilization prolongs and the relaxation rate increases. The relationship between deviatoric stress and time cannot be simply described by linear relation but shows a obvious non-linear tendency. However, the relation between deviatoric stress and time can be simulated by a hyperbolic relation, and based on this relation, a new empirical rheological relation is obtained and the reliability of the rheological relation is verified by the validation results.

With USTX-2000 automatic unsaturated and saturated dynamic triaxial testing system developed by GCTS (Geotechnical Consulting and Testing Systems) company, a series of dynamic triaxial tests under cyclic loadings are performed on saturated sand reinforced with horizontal-vertical(H-V) inclusions of perspex with different confining pressures. The results of dynamic elastic modulus of saturated sand reinforced with H-V inclusions influenced by confining pressure, dynamic elastic strain and the height of vertical reinforcement are studied. Then, the relations between the maximum dynamic elastic modulus which is useful for practical engineering and confining pressure are gained. It is found that the dynamic elastic moduli of both unreinforced sand and reinforced sand decrease with the increment of dynamic elastic strain, and increase with the confining pressure increase; H-V inclusions reinforced sand improves the dynamic elastic modulus along with the increase of the height of vertical inclusion compared to unreinforced sand and conventional reinforced sand with horizontal inclusions. The maximum dynamic elastic moduli of both unreinforced sand and reinforced sand increase with the increase of confining pressure. The damping ratios of both unreinforced sand and reinforced sand increase with the increase of dynamic elastic strain. Neither the damping ratio of unreinforced sand nor that of reinforced sand is sensitive to the change of confining pressure; however, it has the tendency to decrease as the accretion of confining pressure. In addition, the damping ratio of reinforced sand is obviously decreased compared to that of unreinforced sand.

A water infiltration apparatus is specially designed to study the unsaturated hydraulic properties of compacted bentonite-sand mixtures under unconfined condition by measuring the moisture distribution and the swelling pressure during capillary water infiltration. Experimental data show that the water diffusion coefficient is changed with the moisture content of the mixtures (dry density 1.70g/cm3, sand ratio 30%) in a U-shaped curve. It is found that, with the increasing water content, the water vapor diffusivity decreases but the liquid water diffusivity increases. A theoretical analysis is made to estimate the unsaturated hydraulic conductivity, which expresses a general increasing tendency with the increase of water content. With respect to water states, it is found that the unsaturated hydraulic conductivity of water vapor increases at low water content and then decreases, but the unsaturated hydraulic conductivity of liquid water increases continuously at the same time. After water infiltration, the compacted mixtures tended to uniform as judged by dry density. The progress of pressure monitored at different positions of the specimen is found to be closely related to water migration process. For example, the pressure at water inlet surface increased much more rapidly at earlier infiltration stage and then increased slowly. The pressure at water outlet surface, on the other hand, increased continuously. After 96 hours infiltration, the pressure at both surfaces became almost the same. The parameters derived from this experimental research, such as water diffusivity and unsaturated hydraulic conductivity, can be used for safety evaluation of buffer material to radioactive nuclides.

An elastoplastic fracture model for jointed rock mass under compressive loading is presented. In order to account for the mixed mode plastic zone model of wing crack tip of jointed rock under small scale yielding, the dimensionless function of the plastic zone diameter based on the Drucker-Prager (D-P) criterion is derived. The plastic zone models of mode I, mode II and mixed-mode (I+II) are compared with plastic zones obtained by Mises criterion and the influences of different Poisson's ratios for mixed-mode plastic zones of wing crack tip are studied. It is shown that the mode I and mixed-mode plastic zones of D-P criterion are larger than that of Mises criterion; and its mode II and mixed-mode plastic zones are not continuous between the upper and lower surfaces of wing crack. Moreover, plastic yield criterion is employed simultaneously with the fracture softening to describe the behaviors of jointed rock based on D-P criterion. The conception of fracture softening factor is introduced to characterize the softening feature of crack propagation. Regarding the strain energy density of wing cracks at joint-tip is responsible for the evolution of fracture softening of jointed rock. Thus, the behavior of fracture softening can be developed by proposed function of strain energy density. Borja’s strain hardening/softening function is employed as the plastic yield function, regarding the plastic inner variables and stress as two impact factors of the hardening function. The elastoplastic fracture model with its numerical algorithm is proposed; and the code of elastoplastic fracture model is implemented by using return mapping implicit integration algorithm. The influences of friction coefficients, initial joints orientation and stress intensity factor on the constitutive response under uniaxial compression are studied. The results are generally in good agreement with experimental data of uniaxial compression tests of jointed marble.

An in-situ stress measurement and a rock mechanical test under different confining pressures and statistics of structure properties of rock mass in a deep borehole in Beijing have been carried out to research the relation between in-situ stress and rock elastic modulus thoroughly. The results are as follows: the relation between principal stress magnitude and rock elastic modulus shows a positive correlation in granite, but not clear in limestone. In granite, the relative coefficient between principal stress magnitude and revised rock elastic modulus exceeds the relative coefficient between principal stress magnitude and rock elastic modulus. The correlation between in-situ crustal stress magnitude and results of rock mechanical test in high-isotropic rock (e.g. granite) is high, but the correlation in low-isotropic rock (e.g. sedimentary rock) is low.

Centrifugal model tests are conducted to study the bearing capacity, deformation rules and effect of slope inclination on failure rules of soil nail-reinforced cohesive soil slopes when they subjected to a vertical load applied to a strip footing. The failure processes are observed photographically and the displacements of slopes are measured. The results show that the slope stability is significantly affected by the surface load. When vertical load increased, soil deformation concentrated; slip surfaces can be noted and propagated which will eventually lead to collapse of the slope. Under the influence of loading process and strip footing, soil nails closer to the slope surface exhibits an intensive interaction with the soil resulting from the increasing load. As the slope inclination increases, the bearing capacity decreases and the soil exhibits much more obvious movement tendency toward slope surface.

The problem of floor heave of high geostress broken and soft rock roadways, because of its complex geological conditions, is one of the technical problems of coal mining. Deformation and failure characteristics of floor heave of high geostress broken soft rock are analyzed; and the control measures are studied. The results show that, surrounding rock shows compressive shear rheological properties, supporting system should be regarded as a complete system; it focuses on not only surrounding rock repair, stress transfer and enlarged load ring, but also on exploiting the indirect effect of other parts of the supporting system. Comprehensive control measures integrating overcutting floor, high-strength cable, deep-hole grouting, bottom corner rockbolt, side bottom rockbolt and backfill are put forward. Numerical analysis model is established by using FLAC3D; the changes of surrounding rock displacement field and plastic zones are analyzed while using the method; the validity of the method is verified. Comprehensive control measures applied to main roadways of Donger coal mining area, Paner mine, Huainan, makes a good supporting effect.

It is an important topic to predict the settlement, especially post construction settlement, of high fill foundations, which is encountered more and more often in the mountainous areas in western China. However, both the calculation model and calculation method are to be studied further. The characteristics, application scope and parameter values of the hyperbolic model are discussed first; and then the creep mechanism of rockfills is also discussed in depth, especially the reason that creep under laboratory test conditions always finishes in a shorter period than that under filled conditions is explained. After that, a simplified calculation method is proposed to calculate the creep deformation for high fill foundation with uniform thickness in a large area, in which load variations during creep can be properly considered. The rationality and feasibility of the proposed method is demonstrated through numerical comparisons. Besides, by analyzing the results of laboratory tests, the significant relationship between dry-wet cycle deformation and cycle numbers is found, on the basis of which a simplified coupling calculation method that can simultaneously compute the creep deformation and dry-wet cycle deformation is also proposed. Finally, the post construction settlement of a practical engineering project is predicted by the proposed method.

Shear tests along bedding plane on Guzhu expressway schist under natural state and water-saturated state have been carried out in order to analyze the shear strength characteristics of the water-sensitive schist located in northwest of Hubei province under the two states. The results show that：compared with the native state, the cohesion force of the schist under saturation state decreased by 36.7%; the internal frictional angle decreased by 4.6%; the residual cohesion force decreased by 66.7%; the residual internal frictional angle decreased by 11.3%; it is different from the brittle fracture under natural state that the schist shows obvious characteristic of ductility at failure under saturation state. Based on the experimental results，the water weakening mechanism of shear strength parameters of schist has been discussed; a safety factor of a slope located in Guzhu expressway has been computed with limit equilibrium method; and then the evaluation of the slope stability under storm or continuous rainfall conditions has been made.

Utilizing the classical earth pressure theory for setting the reasonable thrust line position of soil slice, the linear equations including as variable are established by the condition of static equilibrium and torque equilibrium, where is safety factor of slice side. Least square method is applied to solving the above linear equations by means of MATLAB program based on the maximum principle and reasonable conditions: . Case studies show that the capacity for resisting shear deformation of slope is brought into play when The slope safety factor decreases with thrust line position increasing; but the impact of thrust on slope safety factor is negligible. The safety factor obtained by the above method is little larger than those by other methods.

By laboratory test and theoretical analysis, the rheological properties of anchored rock and controlling mechanism by anchor are studied. The results show that, non-anchored and anchored specimens’ indoor long-time (above 100 h) creep test is done by RLJW-2000 rheology tester; creep stress threshold of anchored rock is increased by about 30%?c; creep deformations at different stress level stages are significantly controlled; and anchored specimen’s long-term intensity is increased by 5% to 10%?c. In addition, according to the equivalent co-deformation principle, one-dimensional creep constitutive equation of anchored rock is established; the answer of anchored generalized Kelvin (B-K) model is derived. The example shows that rock rheology’s control effect gets better with increasing of bolt consistency, which can be obtained that the anchor’s equivalent stiffness is a dominant factor restraining rock rheology. But from the view of economic technology, bolt consistency and rock rheological parameters have a rational matching interval. The result provides a theoretical basis for the anchorage support design of rock engineering after long-term service.

Based on the modification of Sun’s solution, additional load formulas caused by bulkhead additive thrust and force of friction between shield and soil in double-o-tube (DOT) shield tunneling are put forward by elastic Mindlin solution. Assumed soil is Winkler model, additional load in vertical direction caused by soil loss is deduced by using random medium theory. A calculation formula additional load caused by DOT shield tunnel construction vertical crossed adjacent underground pipeline is deduced. The results show that: during the pass of DOT shield machine, additional load caused by the friction force between shield and soil plays a leading role; additional load on adjacent underground pipeline induced by bulkhead additive thrust is very small which can be negligible; additional load in z direction is mainly caused by soil loss, and the maximum value generally appears above the axis; when pipeline buried depth is near tunnel, the maximum additional load in z direction appears near to center of each single round.

The detonating delay time of millisecond blasting is an important parameter during shaft excavation by one-step deep-hole blasting. If detonating delay time and detonating sequences are reasonable, the millisecond blasting technology has many advantages. The foregoing blasting can create free face and compensating space for the following blasting to achieve the purpose of layered and segmented blasting. Also, the vibration damage of the surrounding rock can be reduced by decreasing detonated explosive charges in every turn. Based on deep-hole millisecond blasting theory, calculation methods of the detonating delay time of presplitting blasting, cut blasting, the same segmentation auxiliary holes blasting and the adjacent segmentation auxiliary holes blasting of shaft excavation by one-step deep-hole blasting are studied. In addition, six kinds of detonating sequences are put forward, such as bottom-up presplitting blasting, up and down before the middle smooth blasting, etc. The one-step deep-hole blasting technique is seen to meet the requirements in the Huaheng coal mine which proves that this research is applicable to other similar projects.

The analysis and prediction of seawall foundation's post construction settlements are very meaningful for engineering maintenance and disaster prevention. Based on seawall's early post-monitoring data in the initial stage of construction, the soil consolidation coefficient is inversed by using layer-wise summation method and Terzaghi's consolidation theory; and an analysis is also carried out the variation laws of consolidation coefficient. In this way, the authors adopt the improved variable dimension fractal prediction models to forecast the consolidation coefficient with strong trends; and then predict the contingent long-term post construction settlement of seawall. As a test, the prediction model is applied to the seawall monitoring data of Beidaihou second east-causeway project (located in Dongtou County of Zhejiang Province). As a result, it reflects well the mechanism of soil body’s consolidation and settlement, and predicts better the trend of seawall’s post construction settlement.

The soil arching effect in micro anti-slide pile system has obviously spatial characteristics when bearing landslide thrusts because of pile body large deformation due to its small diameter. Most current research methods could not consider this point, just treat soil arching effect as plane strain problem. Therefore, based on the particle flow code in 3-dimensions (PFC3D), a series of micro anti-slide pile system tests are simulated to study the formation and development process of the soil arching. The simulation results show that the soil arching effect mainly occurs in the middle and bottom of soil body located nearby the slip plane. The soil arching effect located in the top of soil body is affected by the pile displacement which causes the evident horizontal soil arching formed between piles. Pile length and stiffness have little influence on the distribution of soil arching. It is difficult to form soil arching with the increasing of pile spacing.

In the process of tunnelling with horizontal freezing method, soil volume expansion caused by freezing can produce the phenomenon of surface frost heave. Multiple frozen pipes are usually used to form frozen wall in the actual engineering. Before the circle-crossing period of frozen wall, surface frost heave is induced by superimposed expansion deformation of multiple frozen columns. After the circle-crossing period of frozen wall, surface frost heave is induced by expansion deformation of the whole frozen wall. In view of this, considering the formation process of frozen wall and based on stochastic medium theory, a duration prediction model of surface frost heave induced by tunnelling with horizontal freezing method is presented. Two value methods of freezing outer front radius and frost heave region outer radius are discussed at the same time. Finally, aiming at two engineering cases, surface frost heave displacements are analyzed by calculation model. Variations of surface frost heave displacements with time are obtained, which are compared with field measured results to verify reliability of the model. The model is applied to surface frost heave displacements prediction at any time of freezing period before tunnelling with horizontal freezing method, and can provide effective reference for reasonable determining freezing implementation scheme.

This paper makes a study of the collapsible characteristics under overburden pressure of the Western Henan loess along Zhengzhou-Xi'an high-speed railway by field experiment. The developing process in the depth of loess collapsibility under overburden pressure and the collapsible horizontal distance have also been analyzed. The results show that: the influence of soaking boundary on collapse is very clear; but collapsible rate shows a slow-fast-slow-until-stable tendency, with 60% of the total settlement immersed for 10 days and 90% for 30 days. The of the site is 1.30, greater than the recommended 0.9 by the code. The results show that the extent of collapsibility of this region is more intense than that of general knowledge. In the site, loess collapse under overburden pressure maximum depth laboratory test value is 19 m; and field test value is 16 m, the former is 1.2 times the latter. The collapsible horizontal distance out of the test pit is 20 m, similar with the diameter of the test pit. Therefore, no water should be kept within 20 m from the embankment toe. The research results have been applied to the Zhengzhou-Xi'an high-speed railway construction, and can be taken as reference for similar projects in this region.

As one of the most important factors, pile-soil stress ratio can reflect the load transfer and deformation mechanism of composite foundation. Up to now, as a new pile, no uniform method has been found to calculate the pile-soil stress ratio for X-section pile. Sedimentation basin and filter chamber are typical buildings with concrete floor plate that is considered to be a rigid base. The bearing capacity of pile composite foundation under the rigid base is different from which under the soft base. The in-situ static load tests are carried out based on the foundation treatment project in Qiaobei sewage treatment plant. Besides, a finite element model is built to simulate the cast-in-place X-section concrete pile composite foundation under the rigid base by software ABAQUS. The pile-soil stress ratios are discussed considering some factors including elastic modulus of pile, compression modulus of surrounding soil, pile lengths, cushion thicknesses and compression modulus. The results reveal that the pile-soil stress ratio increases with the increasing of pile modulus, cushion modulus and pile length, while reduces with the increasing of modulus of surrounding soil and cushion thickness. The reasonable pile-soil stress ratio of X-section pile ranges from 20 to 25, corresponding to the pile modulus from 10 to 20 GPa, the cushion thickness from 20 to 40 cm, and the cushion modulus from 30 to 45 MPa.

Moluocun landslide lies on the left bank of the Dadu river and at the tail of Houziyan reservoir. It is at the toe of Suopo deposit, on which the renowned Danba watchtowers concentrate. Due to their unique historical, cultural and sightseeing values, the stability of the landslide is important both to the preservation of the towers and to the selection of rational reservoir level. After introduction to local geoenvironmental conditions, the formation and stability of both Suopo deposit and Moluocun landslide are analyzed based on site investigation and field reconnaissance, numerical evaluation is also made to the stability of the landslide under different reservoir levels and operation schemes by three dimensional strength reduction technique and two dimensional limit equilibrium method. Results show that: Suopo deposit is the result of glaciations. Moluocun landslide is formed due to the long-term creep and disintegration of the toe of Suopo deposit in the past 3 300 years and its total volume is around 40×106 m3. The two diversion ditches constructed after year 1983 raised the water level in the landslide, worsened its stability and made its head and toe crack successively. Under present state, the landslide is in critical state and its safety factor is 1.048 and 1.070 obtained by using 2D limit equilibrium method and 3D strength reduction method respectively. Whether the reservoir level is 1 842 m or 1 852 m, the influence of reservoir impounding and operation on landslide stability is quite small. Drainage is the most efficient measure to maintain the landslide stability and to preserve the watchtowers.

In the framework of limit equilibrium analysis, stability of slope protected by soil nailing is analyzed by using a new method of searching for sliding surface and circular sliding surface method. When considering earthquake, pseudo static method is adopted. Then, according to different modes of slice, a formula of calculating dynamic distribution coefficient of horizontal seism is derived. Aiming at the shortage of vertical slice method of circular sliding surface under earthquake, the mode of combining horizontal slice method with vertical slice method is used. Through analyzing examples and studying the effect of space change of soil nailing and length of soil nailing under different earthquake intensities on the static and dynamic stabilities of slope protected by soil nailing, some conclusions are obtained. The minimum factor of safety (FOS) calculated by new method is quite close to that calculated by circular sliding surface method, and is also smaller than previous results, so it shows that the new method of searching for sliding surface is feasible. In analyzing the static and dynamic stabilities of slope protected by soil nailing, the critical sliding surfaces got by the new method is close to the those got by critical circular sliding surfaces, but they perform the characteristics of non-circular feature. Reducing space of soil nailing and increasing length of soil nailing to a certain degree can effectively improve stability of slope protected by soil nailing under earthquake.

The fuzzy point estimate method of slope engineering reliability evaluation is presented based on the statistical moment point estimate method and fuzzy random theory. The slope stability limit state equation is transformed from fuzzy random set to normal random set, then the point estimation method is used to solve the slope reliability indexes. In view of the approximate distribution types for physico-mechanical parameters of rock mass, the normal fuzzy number, which is different from the normal number is used to do fuzzy random variable. By doing this, the physico-mechanical parameters are closer to its real distribution types. The fuzziness of various mechanical parameters is considered. The calculation results can reflect the true working condition of slope. A case study shows that the method has a higher calculation efficiency and reliable calculation results, and it is convenient in use; it also avoids the shortcomings of traditional methods. The method has great potential for slope reliability analysis of complex slope or functions for implicit expression; it provides a new way to slope reliability analysis and has a broad prospect of application.

Initial cracking law and evolution law of stress intensity factor at the tip of the branch crack of compression-shear fractured rock under high seepage pressure are discussed. The critical water pressure value and the initial cracking intensity criterion of the fractured rock mass under high seepage pressure are established when tension-shear failure occurs. The cracking characteristics under different water pressures indicate that the existence of osmotic pressure aggravates the growth of branch crack; and the branch crack propagation under high osmotic pressure will convent from stable expansion to unstable expansion and cause the shear failure of the crag bridge at the branch crack tip; simultaneously the branch crack interaction is considered, the crag bridge?s cutting penetration damage mechanical model of the compression-shear rock under the high seepage pressure is established. Finally, the flexibility tensor of the rock mass? initial damage and its damage evolution based on damage mechanical effect of fractured rock are studied. Then a damage evolution equation of fractured rock under high seepage pressure is proposed. The theory provides the basis for the quantitative investigation about the compression-shear destruction of fractured rock under high seepage pressure.

The bearing behavior of a new type of prestressed pipe pile with rib (the pile with rib for short) via ABAQUS finite element simulation and in-situ static load test. The comparison between the in-situ static load test of the pile with rib and the common pile with the same outer diameter (500 mm) shows that the ultimate bearing capacity of the piles with rib is 13.10% higher than that of the common piles. The influence of the pile parameters, including the thickness of the rib and the spacing between ribs, on the bearing capacity of the pile with rib is studied. Moreover, the design formula for bearing capacity of the pile with rib is suggested. The formula will provide an important reference for the large scale application of the new type of prestressed pipe pile with rib.

For the strength reduction factor commonly used in geotechnical engineering, its lower limit programming problem is nonlinear and can’t be solved directly by linear programming. Based on the lower limit method and the feature of strength reduction factor and overload factor, the strength reduction factor can be obtained by adjusting the shear strength when the overload factor approach to 1, and thus linear programming algorithm can be fully used. It is shown that the fitted hyperbolic curve method is more efficient and has larger convergence range than conventional methods, such as bisection method and secant method. Suggested method can take full advantage of the efficientcy of linear programming, and is also suitable for application in engineering.

Gas drainage through strata is usually a way of gas control in outburst coal mine. Blasting in boreholes is useful for gas drainage through strata. Taking the blasting practice of Nantong coal mine as research background, the mathematical models of deep-hole blasting through strata are established. Using numerical simulation and verification test from the coal mine, the changes of dynamic stress are respectively studied for blasting holes and control holes; relations between strength of the stress field and drainage effect after the blasting are discussed. The research result shows that the layout of drainage holes and blast holes is associated with the characteristics of gas drainage crossing layer. Due to the blasting hole inclined cross coal seam, dynamic stress distribution of different coal seam sections is extremely uneven; the dynamic stress of center control hole is the biggest compared with other control holes. Under the condition of thin coal seam in Nantong mine, average value of destruction radius is 0.57 m when the charge length of blasting hole is 3.2 m. This value increases 20% more than that of blasting holes of other rows. Charge length of blast hole is an important factor affecting draining gross of gas. The average of gas drainage volume in blasting holes is 55% larger than that of control holes, and the average single-hole flow of blasting drill field is 49% larger than that of the non-blasting drill field’s.

Based on fundamentals of continuum mechanics with Eulerian description method and the corresponding configuration transform relationship, a strict functional form on excess pore pressure (EPP) and void ratio during nonlinear consolidation of saturated soil is presented in this paper to study the development of EPP with a general meaning of nonlinearity. According to the analytical solution to linear finite-strain one-dimensional consolidation by Morris and the presented functional form, analytical solutions to EPP occurred with two-way drainage are put forward for normally consolidated and dead weight consolidated soils respectively. Thereafter, the asymmetry characteristics of EPP and the impact factors are investigated through a numerical orthogonal experiment. The results show that a dimensionless parameter N plays a dominant role in the spatial distribution behavior of EPP during nonlinear consolidation. For the case of non-zero N，the symmetry distribution of EPP in context of classic Terzaghi’s theory is not suited to nonlinear consolidation.

The inverted T-type breakwater with jackets and pile foundations which mixes gravity breakwater with pile is a new type of breakwater; its working mechanism and failure pattern are unclear. A 3D elastoplastic finite element model is established for its stability analysis. Based on the displacement field distribution of the structure in a critical state, the instability mode can be concluded as the inverted T-type breakwater with jackets and pile foundations rotates around a point that is below the top structure and deviates the axis of the pile foundations. For the purpose of engineering application, a simplified calculation method for anti-overturning and anti-sliding analyses is presented. In comparison with the finite element method, the simplified calculation method is reliable.

Assuming a log-spiral sliding surface passing through the toe of retaining wall, based on energy method, the upper bound of active earth pressure for rough walls with inclined backfill is formulated. The formula can be applied to sandy soil and cohesive soil. Extracting the screw-in angle ? 0 and screw-out angle ? h through the slope as variables, hybrid particle swarm optimization is used to search the most dangerous sliding surface globally. Hence, the optimal solution of active earth pressure is obtained. For sandy soil, the earth pressure coefficients in this work agree with the classical upper bound solutions of limit analysis when the inclination of wall is small, but obviously bigger than the classical solutions while the wall angle is larger than 30°. Compared to other well-known solutions obtained by limit equilibrium based on optimum principle, the solution herein is more approximate than that of the classical upper bound solution. For cohesive soil, employing the formula developed by this work to calculate the active earth pressure in an engineering practice, it is found that the relative error between calculation results and measured data is 5.4%.

The Mohr-Coulomb’s model and contact surface model are adopted to simulate the characters of soil and the interaction between pile and soil respectively; a 3D finite element model based on the interaction of piled raft foundation, soil and excavation is established by ABAQUS. It is carried out an analysis for the vertical bearing behavior of group pile foundation considering the effects of pit excavation. The changes of pile top resistance distribution, axial force of piles, lateral friction of piles, pile flexibility and moment due to excavation are discussed. The paper also compared the vertical bearing behaviors of group pile foundation considering and without considering excavation. Through this study, the basic knowledge of the effects of pit excavation on piled raft foundation for high-rise buildings are initially obtained, which would be of some referential significance for the improvement of theories for piled raft foundation design.

Based on principle of minimum potential energy, the government equations of single pile’s load-settlement response are established. The solution of the pile-soil system obtained by using analytical form for soils displacement and difference scheme for pile. The effect of soil’s nonlinearity on settlement response is considered by assuming that soil is linearly elastic-perfectly plastic. And the corresponding computer method is proposed. Then a program is developed based on Maple software. According to the numerical examples, the influences of soil parameters and slenderness ratio of pile on the settlement response are studied. The proposed method is used to analyze a full-scale static loading test pile; and the predictions are in reasonable agreement with the measurements.

Equal safety factor (K) method is recommended for double-slide mode in the code for design of concrete gravity dams(SL319-2005), but there is no unified standard for the determination of the resistance angle between two blocks and it is very sensitive to the calculating result. In this paper, the resistance angle is discussed in detail. In order to get reasonable resistance angle of two blocks, Sarma method, finite element method and the slice-free method of limit equilibrium method are used for the anti-sliding stability of double-slide mode; then a suggestion for determining the resistance angle is given. Finally the stability against deep slide of concrete gravity dam is analyzed and the critical slip surface of double-slide mode is searched.

Oil and gas leakage is one of the most important types of underground storage cavern accidents in salt rock, which has the features like abruptness and inestimable loss. By taking the underground storage caverns in bedded salt of China as research object, its oil and gas leakage risk in the operation process is analyzed; the mechanism of oil and gas leakage accident is revealed and the corresponding fault tree model is established. By analysis, mostly influence factors and fault patterns are found out; and the occurrence probability formula is deduced, which is applicable to the typical underground storage caverns in bedded salt rock. The results show that there are 28 fault patterns of oil and gas leakage accidents of underground storage caverns in bedded salt and this kind of accidents are likely to happen and difficult to prevent; namely, its occurrence possibility is pretty large; according to the calculation results of the basic events’ importance degree, low strength of salt rock, excessive creep of salt rock, fault near the cavern, earthquake, incorrect control of cavern construction parameters, non-uniform ground stress field, human error and so on are the main factors leading to oil and gas leakage accidents. By using Delphi method and fault tree analysis synthetically, it is concluded that the risk probability of oil and gas leakage accidents at five old caverns of Jintan salt mine in recent 10 years is about 0.703%, belonging to incidental accidents.

Based on a visco-elastoplastic model considering the feature of water degradation effect of rock, its finite difference scheme is presented. Through program development for the model by C++ language, the FLAC3D dynamic link library file is obtained. To test the model effectiveness, it is shown that the model program can better simulate the instantaneous elastic deformation, attenuation creep, creep constant, water degradation and plastic deformation characteristics of rock. With the numerical calculation for an on-site tunnel geological model by the visco-elastoplastic model program, it is shown that the vault settlement, convergence and uplift deformation increase with the growth of moisture content, and the time that surrounding rock remains stable is shortened. Uplift displacement in saturated state is twice of that in natural moisture state; and the time that surrounding rock remains stable in saturated state is less than that in natural moisture state for about 40 days; so reasonable construction time for the second supporting is also greatly shortened. The calculation results are consistent with the measuring results in the tunnel site, which can explain the generation mechanism of large deformation disaster effectively. Both stability of rock-support system and reasonable time for the second supporting can be well predicted by the visco-elastoplastic model program presented above.

There are usually several problems during underground mine’s deep-hole blasting，such as large blasting back impact effect, non-uniform pieces and so on. In order to solve the problems in a southern lead-zinc mine, ANSYS/LS-DYNA is used to build numerical models for six kinds of hole’s charging structure with different charging quantities and different coupling coefficients based on parameters of blasting, explosives and rock in this mine. By analyzing information of Von Mises effective stress of blasting simulation, combining with mechanism of rock crack during blasting and Mises yield criterion, the best hole’s charging structure for deep-hole blasting is determined. In-situ test shows that, the optimized charging structure gets uniform blasting pieces; and back impact effect is controlled effectively. Problems of deep-hole lateral blasting in the mine is basically solved, so as to provide optimization of deep-hole blasting’s design with theoretical foundation and technical support.

Inversion parameters are used to calculate and predict long-term deformation of high concrete face rockfill dam (CRFD). Since the construction process and deformation mechanism of rockfill are complex, it is difficult to separate the instantaneous deformation and rheological deformation, and hence it is necessary to carry out the integrated inversion of static constitutive and rheological model parameters. Based on the measured displacement data, static constitutive and rheological model parameters sensitive to the deformation of rockfill dam are selected for inversion. Additionally, a modified particle swarm optimization algorithm (MPSO) based on particle migration and radial basis function neural network (RBF-ANN) are adopted. What is more, by using the trained neural network to describe the relationship between model parameters and displacements, shorts computing time of parametric inversion. The inversion result of Shuibuya CRFD shows that the calculated settlements agree well with the measured data; and dam deformation is within a reasonable range and tending towards stability.

Based on the idea of the initial flow method, initial velocity is introduced to eliminate the velocity that does not exist in dry zone. Darcy formula is extended to the entire region and a nonlinear boundary value problem of the entire region is defined. Through categorizing the potential seepage face as a boundary condition of Signorini’s type, an equivalent variational inequality is established. By combining the continuous Heaviside function, a finite element iterative algorithm of the variational inequality based on initial flow method is given. With this algorithm, a program is developed. Two typical examples are employed to demonstrate the efficiency and robustness of the algorithm proposed here in locating the free surface of complex fracture networks subject to underground water.

Based on the mechanical theory of unsaturated porous media, an equation of electroosmostic consolidation theory which considers the coupling of electrical field, seepage field and stress field is derived by applying the principles of charge and mass conservation, stress equilibrium equation, Darcy’s law and Ohm’s law. The equation is discretized by using the Galerkin method of weighted residuals to get the formulation for finite elements; and then a code is developed. A model test of the electroosmosis combining with vacuum drainage is simulated. The simulated results agree well with the measured ones; it is shown that the proposed theory can predict the development of pore water pressure and displacements quantitatively in the electroosmosis consolidation process.

Based on the microtremor observation data of 539 measuring points in Tianshui, horizontal-to-vertical spectral ratio and the predominant frequency are analyzed. According to the geological records of 59 boreholes and shear wave velocity distribution, two methods including the quarter-wave length and statistical relationship between overburden thickness and predominant frequency are applied to inverse the overburden thickness. The results show that the quarter-wave length has great flexibility to the third and the fourth terraces with a thicker overburden and single stratum; high accurate formula simplifying the influence of shear wave velocity is drawn with the method of the statistical relationship between the overburden thickness and the predominant frequency; and it is suitable for the whole studied area.