Based on the treatment of soft foundation in Chaoshan railway station, monitoring sections and instruments are selected and embedded respectively for observing surface settlement, deep layered settlement, deep horizontal displacement, stress among pile spacing, and extension length of geogrid, etc. The results show that at the beginning of loading, stresses of both soil among piles and pile top will increase rapidly for a while; but the varying speed of stress on pile top is larger than that among pile spacing. When the filling hits a certain height, stress among pile spacing reaches extreme value; the occurring arch effect will make the central stress of four piles become less than that of two piles; the axial force and the side friction of pipe pile have close relationship with the stratum situation and raise along with the passing of time and growth of loadings; the layered settlement of foundation has positive correlation with the speed of embankment fillings; and the settlement value is related to depth and property of stratum. The tension displacement of geogrid ascends with the increment of filling height; and its increasing velocity undergoes a process of first slow then drastic and calm at last. The lateral displacement of embankment grows up with the increment of loadings and decreases along depth, and is effectively controlled by pipe piles.

For multi-braced diaphragm wall structure calculation, a matrix displacement method based on the theory of elastic foundation beam is derived considering the effects of staged excavation upon internal force and displacement as well as the bracing force. Based on the Melan’s solution, combining with the geometrical plane-strain problems, a displacement solution in semi-infinite elastic under horizontal strip load is derived. Furthermore, the horizontal foundation coefficient applied to the above matrix displacement method is gained. Compared with measured results of diaphragm wall obtained from engineering cases, the analysis results indicate that the matrix displacement method is convenient and feasible, and it can provide references to the similar projects.

Seismic response of rock is the main topic in current dynamic analysis of underground structures, but the dynamic response and collapse mechanisms of rock structures are lack of thorough study. Based on a practical hydropower project, three kinds of unfavorable geological structures are selected in the dynamic analysis of large underground caverns by using block theory. Then ground deformation history and characteristics of open and slip joints are studied under seismic loadings by a discrete element program UDEC. Simultaneously the movement mechanisms of the cutting blocks are also analyzed. The results show that steep dip geological structures have greater impact on earthquake response of underground caverns. Under the seismic loading, adverse geological structures slip along the steep incline joint with sudden. Collapse form of adverse geological structures may change with seismic load increasing.

A series of tests are carried out to study the dynamic compaction parameters and their effects on the deep collapsible loess foundation under super-high fill in Lishi region. Analyses are made on the average settlement of each test area before and after dynamic compaction and on the regularity of the main physical and mechanical indexes of soil. The main parameters are gained, such as the centre distance of dynamic compaction points, the best impact number, the standard of cutting out, and the effective reinforcement depth under the energy levels of 2 000 kN•m, 3 000 kN•m or 6 000 kN•m; hence, the empirical formula of the effective reinforcement depth of dynamic compaction is given. The results of the tests show that the deep collapsible loess foundation in Lishi region can be effectively reinforced by dynamic compaction and that the loess collapse in the reinforced range is removed. Moreover, the results show that after dynamic compaction above the energy level of 2000 kN•m, the eigenvalue of the bearing capacity of collapsible loess foundations in Lishi or similar regions can reach over 300 kPa, the foundation soil deformation modulus is more than 25 MPa, and the effective reinforcement depth can be computed by the modified formula Menard, in which the modified coefficient is 0.35-0.37. Furthermore, the results indicate that under the energy levels of 2 000 kN•m, 3 000 kN•m or 6 000 kN•m, the best impact numbers of dynamic compaction are 11, 10 and 10 respectively; the effective reinforcement depths are 5 m, 6 m and 9 m respectively; the optimum centre distances of dynamic compaction points are 4m, 4m and 5m respectively; and the average settlements of the last two impacts, which are not more than 5 cm, 5 cm and 10 cm respectively, can be used as the optimum standards of cutting out. Therefore, the results of the tests can provide a reference for the design and construction of engineering projects of the same kind.

At present, heavy metal pollution in the leachate of waste disposal site only can be controlled by hydraulic barrier of extremely low permeability. The chemical field of the barrier has never been used for the retardation of heavy metal pollution. A conception of “sewage sludge barrier” is proposed based on the integration of low permeability with plentiful organic matter and anaerobe contained in the sewage sludge. To investigate the feasibility of the sewage sludge barrier, the flexible wall permeameter is used in this study to measure hydraulic conductivity of sewage sludge under different effective stresses; and the chemical properties of the effluent are monitored. Test results show that with the increase in effective stress, the dry density increases and the logarithm of hydraulic conductivity decreases linearly with decrease in void ratio. The formation of biofilm and inorganic precipitates with the anaerobic respiration, and the increase of the thickness of diffuse double layer of the clay particle within sewage sludge specimens are also responsible for the decrease in hydraulic conductivity. Hydraulic conductivity of sewage sludge as low as , combined with strong adsorption and neutral to weak alkaline reducing conditions induced by the anaerobic respiration, makes the heavy metals of Zn and Cd retarded effectively.

A laboratory model experiment system for subgrade drainage is designed and processed (declared a national invention patent); and the study of the subgrade moisture migration and laboratory underground drainage experiment under the influence of groundwater level fluctuation is conducted. By changing the height of the groundwater level, the dynamic response of subgrade humidity is studied in the case of without any waterproof measures, adding ordinary sand cushion, new drain material as underground waterproof and drainage base; and its effect of subgrade is evaluated. The results show that under the influence of the groundwater level fluctuation, the moisture of subgrade near the groundwater changes with the water table accordingly, the upper soil moisture has a relatively substantial increase because of the capillary action; when the water table is low, sand cushion plays a good waterproof and drainage effect; when the water table is high, the rise height of capillary water within the sand cushion is higher than the height of the sand cushion; and the subgrade moisture has a greater changes; new drainage materials can prevent the capillary water entering into the subgrade effectively; and it has good waterproof and drainage effects.

Dredged material (DM) solidification technique was gradually put into engineering application in China, determination of the compressibility behavior cement-treated clays is of great importance to direct DM solidification engineering. Compressibility behaviour of cement solidified dredged material (SDM) was conducted through single factor experiment considering initial water content, cement content and curing time in the oedometer tests. Results show that the significant characteristics for the SDM compressibility is there exist a yield stress, when external load is below the yield stress; the compressibility is very low, however, once the external load exceed the yield stress, the compressibility of the SDM suddenly increases to more than 20 times at the post-yield state than that pre-yield state, and is also larger than that of the untreated dredged material. The untreated dredged material is belong to high compressibility soil according to criterion, and the cement treated dredged material transfers to medium or low compressibility soil. Yield stresses of SDM increase linearly with increased cement content; lower water content and longer curing time get larger yield stresses. The compressibility behaviour of SDM is similar to that of the natural sedimentary soils, double logarithm compression pattern is fitted to depict the sudden drop compressibility behaviour of SDM.

In order to investigate the mechanical and deformation characteristics or action effects caused by vehicles and impacts on important parts of bridge or tunnel connecting sections under weak surrounding rocks especially grade Ⅳ or Ⅴ surrounding rocks, systematical indoor model tests have been carried out. The relationship among physical quantities and the similarity indexes have been worked out under the dimensional analysis method of the similarity theorem considering the characteristics of bridge and tunnel connecting projects. The model test methods such as test contents, working conditions, test equipments and instruments etc., have been systematically analyzed and elaborated. Through analyzing the test phenomena and results, some conclusions are drawn as follows: the vehicle loads with impact actions during post operation stage cause harmful mechanical effects or structure damages on some key parts of bridge or tunnel, such as oversize displacement on bridge mid-span and lap joint tip or oversize settlement of tunnel bottom, or lower stability of surrounding rocks nearby tunnel entrance etc. Consequently, for bridge and tunnel connecting projects under Ⅳ or Ⅴ surrounding rocks, some key parts of bridge, tunnel lining and surrounding rocks nearby the entrance should be strengthened in order to avoid damages or diseases .

Based on the progressive rupture mechanism in the backfill, the modified Coulomb's solution of earth pressure against flexible retaining wall is developed; and the nonlinear relationships between the wall movement and the angles of internal friction and wall friction are derived. It is applied to an improved solution for beam on a nonlinear elastic foundation. So that a new calculation of earth pressure against flexible retaining wall considering displacement is obtained. Comparisons of the calculated results with observations from model test show that the calculated results of the earth pressure has a satisfying agreement with the observations. This calculation can give some references to design of flexible retaining wall.

Fissures which almost exist in all of expansive soils always result in failure of expansive soil slope. Shear strength characteristics of fissure-plane are studied; and a new triaxial test method is recommended with typical expansive soil taken from Nanyang section of middle route project for South-to-North Water Transfer. The computerized tomography (CT) technology is firstly introduced to shear strength test of fissure-plane. The real failure stress of fissure-plane is analyzed accurately through measurement of the fissure-plane’s real occurrence by CT scanning; and shear strength parameters determined method is provided for triaxial test of fissure-plane. The test results show that the peak strength of fissure-plane is much lower than that of bilateral expansive soil without fissures and even smaller than residual strength of bilateral expansive soil without fissures. The reasons of these phenomena are that gray clay in fissures has higher water content, smectite content and particles orientation degree. Leaching behavior of groundwater generates three aspect alternations to fissures. In microscopic view, leaching changes ferric iron oxide in expansive soil to ferrous oxide and that results gray clay in fissures whose color is different from expansive soil besides fissures. In mesoscopic view, mineral composition and particles arrangement of expansive soil have been modified by leaching and filling material in fissures have higher smectite content and particles orientation degree. In macroscopic view, factors mentioned above result in significant difference between fissure-plane and bilateral expansive soil.

Large diameter pile with variable cross-sections is applied to the region of bride engineering and foundation treatment. It is necessary to study the vertical bearing behaviors and working mechanism. The relation between vertical bearing capacity and settlement & distribution of the axial forces and skin friction along pile and failure mode of the pile are discussed based on laboratory test. According to the test, it is concluded that it is clear that the vertical bearing behaviors of the pile is affected by the ratio of variable diameters b value; the b is more smaller, the vertical bearing capacity is more smaller. It is proved that how to choose the b is controlled by the lateral bearing behaviors. The squeezing effect is not clear to improve the vertical bearing capacity unless the top displacement of the pile reaches a certain value.

Calcareous sand is a special marine geotechnical sediment, which has unexpected physico-mechanical property due to its composition and structure. Study of dynamic characteristics of saturated calcareous sand under explosion has important theoretical and practical significance. This paper aims at studying attenuation rules of earth pressure, pore pressure and vibration acceleration in different relative density calcareous sands due to explosive load through model experiment. Results show that explosive wave attenuates as the distance increases in saturated calcareous sand, and attenuation speed decreases as the distance increases. Explosive wave attenuates slower as relative density increases; excess pore pressure due to explosion reaches the peak value within 10 to 30 millisecond, and about 90 percents excess pore pressure dissipates in the previous 3 minutes; since delay explosion is used in this experiment, dynamic behavior of saturated calcareous sand is more intensive because of explosive wave overlap. Calcareous sand has strong absorption and attenuation effect for P-wave due to its particle breakage characteristics, and about 25% explosion energy loosed to form crush zone, compression zone and damage zone.

The anti-slide pile is an important method to treat landslide at present. Because of the particularity of rock and soil masses, there are many differences between the practical engineering, landslide thrust of landslide at the back of the pile, soil resistance, failure mode of pile deformation, and theoretical calculation. So we’ve done the physical model test of fortifying landslide with cantilever anti-slide pile, loaded step by step on the top of landslide mass, then obtained some phenomena and lots of test data, the landslide thrust at the back of the pile, soil resistance in the front of the pile and pile strain by using testing equipments. According to the test data, pile failure mode and variation of landslide thrust distribution and soil resistance are analyzed. The test results show that the cantilever anti-slide pile is divided into two parts: separated part and contact part; then landslide thrust has gradually concentrated to the contact part as load increases. Soil resistance in the front of the pile is mainly above 25 cm. It decreases with the depth increasing. The failure model of cantilever anti-slide pile is break-off and the failure point of pile lies 25 cm below the sliding surface. The reason is soil yielding in front of pile caused a large displacement of the pile top and the pile broke off. Finally landslide is instable. These results have reference significant for the actual engineering.

 ring-shear test; residual strength; slide zone soil; Huangtupo landslide Slide zone soil of Huangtupo landslide is studied in detail as a typical example in the Three Gorges Reservoir. Three types of shear methods, including single-stage shearing, pre-shearing and multi-stage shearing, are conducted to investigate the residual strength of slide zone soil by employing ring-shear apparatus. It is conducted that the formation of shear band of slide zone soil is relevant with the shear displacement; the residual strength increases with the increasing of effective normal stress. For slip soil sample with a pre-existing shear band, residual shear strength can be soon and easily reached; initial dilatancy phase, contraction phase due to grain migration and constant contraction phase make up shear settlement curves of different ring-shear tests and the changing trend of shear stress in each stage is different. The residual strengths obtained from pre-shearing test and multi-stage test are larger than the actual value; the single stage shearing should be the preferred approach to acquire residual strength of slide zone soil.

Through preparing different water contents remolded dredged material, the influences of water content on the undrained shear strength of remolded dredged material by laboratory miniature high-precision shear vane apparatus are studied. The precision of the apparatus is 1 Pa. The experimental results show that the measured data are reasonable. But, the lower the shear strength of remolded dredged material is, the bigger the relative average deviation of the experimental results is. Test results show that the influences of water content on the undrained shear strength of remolded dredged material are obvious. Undrained shear strength decreases with increasing the ratio of water content to liquid limit (w/wL). The bigger w/wL is, the smaller is downtrend of undrained shear strength. When w/wL is the same, undrained shear strength of remolded dredged material is almost the same. Undrained shear strength linearly decreases with the increase in w/wL in the bilogarithmic plot. Relation between undrained shear strength and w/wL for all kinds of remolded dredged material is derived, undrained shear strengths of all kinds of water contents for all kinds of remolded dredged materials are derived by this relation. The test results of this paper are bigger than the calculated values of relation by Hong Zhen-shun. The test results are consistent with the calculated values of relations by Locat and Leroueil when IL >2. The test results are bigger than the calculated values of relations by Locat and Leroueil when IL<2.

Large amounts of sludge are produced in China every year. Non-hazardous treatment and recycling technology is vital for industrial production to deal with sludge pollution problems, in which sludge solidification technology is of great importance. The hygroscopic and self-hardening properties of paper sludge ash are the beneficial to produce cost-effective sludge curing agent formulation. It is a worthwhile and environmental friendly to make use of wastes induced by paper production industries. The basic engineering properties of paper sludge ash have been studied in this study first. Furthermore sludge solidification tests have been carried out, including pH value, heavy metals in the extracting solution, hygroscopic property, microstructure and shear strength, and on the basis, the unconfined compression strength of solidified sludge using paper sludge ash. The results indicate: the paper sludge ash is weakly alkaline, the extracting heavy metals is of little pollution, hygroscopic property decreases with increasing pressure and there is a minimum water absorption; shear strength decreases with the water content increases; paper sludge ash can improve the unconfined compression strength of solidified sludge; and the shear strength increase obviously with higher cement content.

Ground deformations induced by normal fault can cause severe damages to infrastructures and pipe line systems nearby. In this paper, the results of a centrifuge test simulating multiple-step normal faulting in saturated clay are reported. The test focuses on the area and characteristic of distortion zone, fault propagation and location of surface ruptures. Based on the test, it is found that (1) the magnitude of normal fault movement has insignificant effect on the area of the distortion zone at the ground surface; (2) the shape of distortion zone in the clay is triangular and the width of this distortion zone at the ground surface is about the same as the depth of the soil underneath; (3) the main fault rupture propagates upward vertically; and (4) surface ruptures are located at the edge of the distortion zone on the side of the bedrock foot wall. Normal fault displacement required for the development of tension cracks at the ground surface is smaller than that required for fault rupture to outcrop the ground surface.

To study the reinforcement effects of different forms of bolt bolster plates under explosion, two different plates, namely face plate and bowl-shaped plate are selected in the field explosion test. Macroscopic failure pattern, displacement characteristics of tunnel wall, relationship between vault displacement and proportion distance, and vault displacements of both sides of explosion center are compared. Furthermore, reinforcement effects of the two plates on tunnels under the condition of explosion are analyzed. Test results show that bowl-shaped plate can bring tensile strength of bolt into full play; and stiffness of rock mass can be greatly improved. Reinforcement effect of bowl-shaped plate on rock are better than that of face plate.

In the translational displacement mode, a stress of wedge soil between rigid retaining wall and sliding surface, which is in the passive state of limit equilibrium, is analyzed. Considering the horizontal equilibrium of the soil between the wall and the slip surface, the formula of passive earth pressure coefficient and the angle of failure line to horizontal are obtained by using the principle of soil arching effect. According to the equilibrium equation considering the static equilibrium conditions of horizontal unit of soil, the formula of the passive earth pressure distribution, the resultant earth pressure and the application point of resultant earth pressure on retaining wall are respectively set up. After comparing the computed result using the method mentioned above with the experiment results and the results obtained on the basis of Coulomb and Rankine theories, it is demonstrated that the calculating results agree well with the experimental results; and thus the calculating method obtained is verified rational.

Taking granite as samples, a freeze-thaw cycle experiment (with the temperature ranged from -40℃ to 20℃) is conducted. The highest cycles are 100. Nuclear magnetic resonance (NMR) technology is employed to observe the rock damage changes. The results show that freeze-thaw cycle action will produce damages to the sample. Some samples crack after a certain cycles. Both the T2 spectrum and NMR image indicate that the action of freezing and thawing cycle redistributes the inner structure of sample. The T2 curves change greatly after the cracks emerged. Finally, damage mechanism is adopted to analyze granite damage principle in condition of freeze-thaw. An equation of material continuity and porosity is obtained. Then an equation between effective stress and porosity is established. Taking N-4 for example, the relationship between effective stress and cycles is obtained.

Three-dimensional particle flow code(PFC)is adopted to simulate the true triaxial tests of rockfill. Not only the macro stress and deformation characteristics of the rockfill under three-dimensional stress conditions are researched, but also the micro and macro parameters are then linked with each other in order to further improve the study of rockfill. In the process of the test, the ratio of intermediate principal stress is fixed. By comparing the results of rockfill true triaxial test based on PFC and the results of true triaxial test in laboratory, we find that the PFC can suitably simulate the mechanical properties of rockfill. The PFC numerically experimental results indicate that the intermediate principal stress has a remarkable influence on the strength and deformation of rockfill under the three-dimensional stress condition. When stress ratio parameter change from 0 to 1 , the intermediate principal stress surface compresses firstly and inflates later; the minor principal stress surface is always on the compression state. The intermediate principal stress is influences on the internal friction angle, the elasticity coefficient and the Poisson's ratio. In a mesoscopic view, we find that the higher confining pressure is, the higher value of b is, the greater particle coordination number is, and the smaller porosity factor is. The rockfill macroscopic stress and deformation phenomena are explained from microscopic angle.

The reuse of scrap tires in civil engineering may not only to prompt new way of disposal scrap tires but also provide new geosynthetic materials to help solving geotechnical problems. In this study, unconsolidated undrained triaxial test was undertaken with the goal of evaluating the shear strength of granulated rubber/loess mixtures (GR-LM) with different rubber contents (10%－ 50%). The mechanism of test is explained. It is found that GR-LM shows stress-strain hardening behavior associated with rubber content and confining stress; and granulated rubber shows a linear stress-strain behavior. The optimum rubber content is about 30%, which offers higher strength under low confining stress compared with rubber contents. The critical content of GR-LM is analyzed from the viewpoint of GR-LM meso-structure. By combination of porosity structure and loess matrix state, the influence of rubber content on the shear strength of compacted GR-LM was reasonably explained. The shear strength of GR-LM shows like silt soil to granular soil with different contact relationships of elastic skeleton particles under different rubber contents and confining pressures.

Flexible slope protection geocell is an economic, convenient and eco-friendly technique; and it is increasingly used in practical projects. However, geocell is sensitive to the ambient environment; and it might lose its stability due to rainfall infiltration. In this paper, the shear failure behavior of the geocell system under rainfall infiltration is analyzed. By adopting the limit equilibrium method, a slope stability analysis model is established; and the influences of soil moisture content, slope angle, rivet space, slope length, slope wash and geocell depth on stability are analyzed. The research result would provide technical support for the design and stability analysis of flexible slope protection geocell system.

The chemosmosis performance for long-term solute permeation in the geosynthetic clay liner (GCL) is obvious. The laboratory test of permeation with solute is introduced. And the test result indicates that the cation exchange has largely effect on the hydraulic conductivity of GCL. The hydraulic conductivity of GCL is up to 2.5×10-11 m/s and 5.6×10-11 m/s permeated with 10 mM and 30 mM CaCl2 solution respectively. The time of solute breakthrough the GCL decreases with the solution concentration increasing. The change of the hydraulic conductivity of the GCL is impacted largely on the presaturation reagent. The effect of the hydraulic conductivity of GCL by using the distilled water for presaturated sample is much smaller than that using the CaCl2 solution. Considering the effect of the membrane behavior and cation exchange, the coupling dynamic model of solute transport has been developed. And the coupling model is applied to modeling the variation of the solute concentration in permeation process. The Ca2+ concentration is anastomotic by data match from the test and simulation result; and the reliability of the coupling model is approved. The chemosmosis in GCL is important, which can effectively delay the solute transport velocity described by the breakthrough curve of Ca2+ concentration and flux. Moreover, the level of the retardation effect by chemosmosis becomes obviously with decreased of the solute concentration. Therefore, the effect of the chemosmosis should be taken into account for analysis of the solute transport in GCL.

Based on the region block #1 of the first-period peninsula in Wenzhou tidal land, in-situ static load tests have been conducted on thin-wall tubular piles, bored piles and prestressed pipe piles. The results indicate that compared with bored piles and prestressed piles, thin-wall tubular piles are widely use in the foundation treatment of tidal flat soil due to its advantages of no sediment, high quality, weak pile driving effect, cost-saving, meeting the requirements of bearing capacity and settlement of pile top. In addition, no plugging happens during driving thin-wall tubular pile in tidal flat soil. The soil plug and cover plate on pile top have contribution to increase bearing capacity to some extent. At the same time, in order to increase bearing capacity, thin-wall tubular pile can be lengthened appropriately.

The values of shear strength parameters, c and φ, estimated by two linear regression methods from data of rock or soil triaxial test are different. To reveal the basic cause of differences between the two regression methods, the principle of linear regression based on the least square method is analyzed thoroughly. The results estimated by regressing maximum principal stress with minor principal stress are the best values, while the results obtained by regressing maximum shear stress with average normal stress are not reliable. Modification for least square method of the latter regression method is done to obtain uniform results. Formulas for calculating modified regression coefficients are deduced. It is proved that results by the two methods after modification are the same; and they are applied to calculate the shear strength parameters in triaxial tests of phyllite. The results show that to rock or soil triaxial test, the values of shear strength parameters calculated by the two methods after modification are also the same best and unbiased estimations.

Because large quantities of loose deposits were accumulated in gully after “5•12” Earthquake, the occurrence probability of gully debris flow is enhanced greatly in rainfall. However, due to the special conditions of provenance and disaster environment, the traditional theory cannot be used to expound the mechanism of gully debris flow and prevent the disaster effectively as ever after the event. Here, based on hydrology, the hydrological model of ground water table in loose deposits is established first. Then by aid of hydraulic theory, the change of hydraulic characteristics and the variation of hydraulic power with the rising of groundwater level are analyzed. Furthermore, the calculation formulas of hydrodynamic and hydrostatic pressure are also proposed. Finally, by applying infinite slope theory in calculation of sliding force, anti-sliding force and residual sliding force acting on each segment, the failure mechanism of accumulation body is illustrated clearly with an example. The result indicates the failure of loose deposits in rainfall is the result of increase of the hydraulic power with the rising of groundwater level. Those deposits which have small coefficient, gentle slope, narrow-deep gully and large basin would be easy to fail because of its high hydraulic pressure generating in rainstorm, and the failure modes can be divided into two types according to residual sliding force as pushing failure and hauling failure.

To forecast and assess the hazard mechanism of catastrophic landslides, based on the data of earthquake and rainfall-induced catastrophic landslides, the relationships including the equivalent friction coefficient (H/L), the maximum horizontal distance (L), the maximum vertical distance (H) and the landslide volume (V) are studied. The relationships among H/L, L, H and V are power laws, in which there are negative power laws between H/L and V and the positive power laws among L, H and V. The horizontal and vertical movement distances of the seismic and the rainfall catastrophic landslides are different in the same scale. The H/L=0.42 is taken into consideration in the standard of landslide long-runout. It is not significant between seismic induced catastrophic landslides and the landslide long-runout, but there is remarkable relationship between rainfall induced catastrophic landslides and the landslide long-runout. The dominate distance of landslide movement can be analyzed based on the movement distances of the 80% landslides; the dominant distances of the horizontal and vertical movements of seismic and rainfall catastrophic landslides are different in the same scale. The results indicate that the movement distances of catastrophic landslides are not only controlled by the volumes but also related to occurrence mechanism. And they can provide references for forecasting and evaluating the hazard region and strength induced by the earthquake and the rainfall catastrophic landslides.

Using four-fold line strain softening model which considers the structure damage, according to the effect of squeezing soil when pipe sinking, the improved cylindrical cavity expansion theory is deduced; and it is compared with the existing models; the results indicate that the simplified four-fold line model is proximate with the typical compressing curve; and the method for determining each line and relevant factors is put forward. The formulas of stress and strain for each region around pile and the method for determining ultimate softening radius, ultimate destructive radius and ultimate expanding press are obtained by using Mohr-Coulomb yield criterion and associated with flow rule. On the basis of engineering case study, the improved cylindrical cavity expansion theory using four-fold line strain softening model is compared with the existing models; the results indicate that the displacement calculation of four-fold line model is the closest to the measured value; so the model can satisfy the practical engineering of squeezing soil more effectively.

The Rayleigh wave velocity of dynamic compaction foundation which comprises detritus soil is tested under three groups of different soil-rock ratios to research soil-rock ratio and large size rock block influence on reinforcing effect. The curves of wave velocity after dynamic compaction present obvious catastrophe characteristics, which are enhanced with soil-rock ratio reduction, and its catastrophe segment is consistent with location of large size rock block. The curves of its wave velocity increasing proportion present vertical partitioning characteristics; and the soil-rock ratio influences more on reinforced thickness. The surrounding soil of large size rock block is strongly disturbed; and the wave velocity sharply reduced; especially located near the site surface or much large rock blocks. The reinforced depth is reduced with increasing buried depth of large size rock block which located in strong encryption zone, and it gets more shallow when its buried depth closer to the peak value of wave velocity.

Combining the dynamic consolidation of a nuclear power plant foundation, varieties of in-situ tests are used to monitor the vibration intensity and safety of cutoff wall under dynamic compaction. Through experimental research, dynamic compaction parameters which ensure the cutoff wall safety and the dynamic compaction effect are analyzed; the controlling standard for long-term dynamic compaction is given. The long-term monitoring results show that the adopted monitoring scheme is reliable and efficient so as to provide a very important reference for the similar projects? safety assessment.

In order to minimize coal resource loss and mitigate the support difficulty of reused gateroad in double-U shaped gateroad layout of high gassy coal mine, a numerical simulation is used to investigate the stress distribution and deformation rule of reused gateroad with respect to different pillar widths. Results show that with one side pillar width increasing, vertical stress peak in surrounding rock moves close to the gateroad and then gets away in one direction. When the pillar is slender, the deformation of slender rib and roof are larger than that of the wider rib and floor. Floor heave increases and becomes the main convergence with pillar width increasing. With stress peak ratio in coal pillar as an indicator, the division of barrier pillar width reveals the relationship between pillar width and gateroad stability. Research results are successfully applied to an engineering practice, and it provides guidance for gateroad layout in the similar situation.

Apparent particle size grading is an important characteristic of superhigh bench dumping site; and the critical factors with the impact of its stability and disaster prevention are the fragmentation distribution and shear strength parameters of accumulate granulae. With the copper mine dumping site which has the feature of apparent particle size grading in Jiangxi province, the study of on-site particle size investigation and indoor laboratory tests are carried out. The particle-size distribution law with the changing of dumping-site height is analyzed; and quantitative relationship between the fragmentation distribution and the shear strength parameters of granulae is discussed. The research results indicate that the mean grain size , the coarse-grain contents P>5mm and the maximum grain size are increased significantly according to the decreasing of dumping-site height, which show that the dumping-site has the feature of apparent particle size grading. The distribution value B, by using the Gandin-Schuhmann model, fits the decrease with the increment of dumping-site height. The coarse particle content in the grain size composition and the internal friction angle φ of shear strength parameters increase with the obvious increment of the distribution value B. The relationship between distribution value B and the internal friction angle φ can be expressed by exponential function curve.

Based on the issues of roof collapse in fault zones, roof elastic thick outrigger mechanical models in normal fault zone and reverse fault zone are established; the roof stress distribution law is researched; and the roof collapse mechanisms under different roof pressures, different support strengths, different span-depth ratios, etc. are analyzed according to the Mohr-Coulomb failure criterion. Theoretical analysis shows that the maximum effective shear stress of roof thick outrigger increases with the growth of span-depth ratio; and it presents three different kinds of fracture modes with the increasing of span-depth ratio; support strength should be enhanced in the roadway crossed faults; surface protection effect should be enhanced near normal fault plane. According to the theoretical analysis, pressure relief anchor box beam support system is put forward to apply to fault zones, by which roof is supported opportunely and forcefully; and the effect of first anti-pressure, then pressure relief, at last anti-pressure is implemented; and the support system works effectively; the self-bearing ability of surrounding rock is put into full play. The mechanism research conclusion is applied to the support scheme in similar fault zones of the mine; and it prevents roof collapse accidents effectively, so as to prove that the conclusion of theoretical analysis is correct.

A field measured model which is 12 m high is built to study the long-term performances of grid reinforced slope. At the same time, a numerical procedure based on finite element methods for analysis of behavior of deformations and stresses of reinforced earth structures is presented. In the proposed method, the nonlinear creep behavior of both backfill and geosynthetics used for reinforcements is taken into account by using the rheological models of visco-elasto-plasticity and nonlinear visco-elasticity respectively. Additionally, the panel and the backfill as well as the panel and the panel are rationally considered. The layer-by-layer filling process of backfill of retaining wall is also simulated. Comparing with the conventional calculation methods and the field measured data, the effectiveness of the method is proved tentatively. Meanwhile, the failure mode, the distribution of tensile stress of reinforcing materials and the safety index in high reinforced retaining walls are obtained.

Numerical models of frictional arch, end bearing arch and united arch of anti-slide pile structures are established with FLAC3D. Differences and similarities between three arches about formation, development and law of effect factors are researched comparatively, as well as the combination mechanism of each single one. The results show that the united arch’s development starts with the frictional arch’s forming and ends with the end bearing arch’s breaking. And during all the progresses, each single arch exists and occupies some dominant areas severally. The united arch’s distribution, limit capacity and plasticity zone are almost made up of the two single arches’. Different factors have different influences on both quality and quantity of the same arch, while the same factor has different influences on different arches only quantitatively. So a new method which can help us come to understand it much better is put forward by separating the united arch and combining the two single ones.

Response displacement method is a kind of simple and practical analysis method for aseismic design of soft soil tunnel, for the method can reflect dynamic reaction behavior of soft soil tunnel under aseismic load. Taking square section tunnel for example, the accuracy of the method has been verified by comparing its predictions with results from a soil-structure whole dynamic finite element method. Based on plane strain assumption, the analytical expression for soil spring stiffness has been deduced from the function of complex variable method in elastic theory for the purpose of simplifying the calculation process of response displacement method. The analytical solution for soil spring stiffness has been verified by comparing its predictions with results from finite element method. The analytical expression for soil spring stiffness has been applied to response displacement method. Meanwhile, simplified calculation models for shear stress and seismic response displacement of free soil field have been adopted. The whole dynamic finite element method has been used to validate the accuracy of simplified response displacement method for transverse secion aseismic analysis of soft soil tunnel

The grey relational analysis (GRA) and stepwise discriminant analysis (SDA) for water source identification of mine water inrush are selected to be basic models. The advantages and disadvantages of both models are analyzed as well as the problems of one applied alone, and the idea of coupled identification is proposed to build GRA-SDA coupled model. Six sets of ions (Na++K+, Ca2+, Mg2+, Cl-, SO42-, HCO3-) and total dissolved solid (TDS) are selected from the sample data of a mining area as discriminant factors for model verification. The analysis shows that the identified results meet the actual situation very well; and the coupled model enhances the identified accuracy efficiently compared with applying one analysis method alone.

On the basis of using the models of stress corrosion and pressure solution established by Yasuhara et al, the solute concentration field is introduced into the 2D FEM code of thermo-hydro-mechanical coupling analysis for dual-porosity medium developed by the authors. Aiming at a hypothetical nuclear waste repository in unsaturated rock mass from which there is a nuclide leak, two computation conditions are designed: (1) the fracture apertures are changed with the stress corrosion and pressure solution (the porosity of intact rock is also a function of stress); (2)the fracture apertures and the porosity of intact rock are constants, then the corresponding two-dimensional numerical simulation for the coupled thermo-hydro-mechano-migratory processes is carried out; and the states of temperatures, rates and magnitudes of aperture closure, pore and fracture pressures, flow velocities, nuclide concentrations and stresses in the rock mass are investigated. The results show that the aperture closure rates caused by stress corrosion are almost six orders higher than those caused by pressure solution; and the two kinds of closure rates climb up and then decline, furthermore tend towards stability; when the effects of stress corrosion and pressure solution are considered, the negative fracture pressures in near field rise very high; the fracture aperture and porosity decrease in the case 1, so the relative permeability coefficients reduce; therefore the nuclide concentrations in pore and fracture in this case are higher than those in case 2 because the effects of negative pore and fracture pressures on the stress balancing are not reckoned in; the magnitudes and distributions of stresses within the rock mass in two calculation cases are almost the same.

Due to the randomness of dynamic loads and structural parameters, dynamic reliability of stability between layers of RCC gravity dam deserves the attention. Considering the randomness of spectrum characteristics and peak acceleration of seismic waves as well as material parameters of the dam, potential sliding paths of the dam subjected to earthquake can be identified by generalized statistics; based on stochastic finite element method (SFEM) results, the limit state function of dynamic sliding is built according to rigid limit state criteria and response surface method (RSM) under a certain seismic loading; the reliability index is got as well; then, considering the relativity between different failure paths, the reliability index of the system can be estimated by Ditlevsen narrow-bound method. Finally, the randomness of seismic load is taken into account, the numerical integration method based on complete probability formula is used to get the dynamic system reliability. The results indicate that the system reliability between layers of gravity dam no longer depends on the failure path of the foundation plane, but is closely related to the failure paths at the downstream fold slope when the horizontal earthquake coefficient is greater than 0.2. This method is mathematically clear and practical.

A new meshless numerical method for frictional contact problem is presented. In order to represent the discontinuous displacement field along contact surface and stress singularity around the contact surface tip, a discontinuous function and asymptotic crack tip displacement fields are added to the standard displacement formula based on the idea of partition of unity. Then, combined with frictional contact laws, a linear complementary model with the meshless method is formulated. In this approach, contact interface equations are discretized by contact point-discretization; and the global discretized system equation are transformed into a standard linear complementary problem that can be solved readily by using the Lemke method. Numerical examples show that the method is effective for solving the frictional contact problems.

It is shown that the water tables of leachate in many early valley-type MSW landfills in Chinese Southern Region are very high by the operating experiments in last ten years. It is shown that the high water table of leachate by rainwater infiltration is a main factor induced MSW landfill landslide by many literatures. So, it is very important to investigate the water transport responses and the stability of valley-type MSW landfills under heavy rainfall. Firstly, based on the soil-water characteristic curve of shallow, middle and deep layer MSW in Qizhishan landfill and Brooks-Corey equations, the permeability function of MSW landfills is given by nonlinear curve fitting. Secondly, numerical analyses are conducted to investigate water transport in Qizhishan valley-type MSW landfill subjected to rainfalls with four different patterns, i. e. delayed, central, advanced and uniform rainstorms. At last, the stability of Qizhishan landfill has been studied by limit equilibrium method. The computed results show that rainfall pattern has a significant influence on water transport in valley-type landfill and its stability, and the delayed rainfall is found to be the most critical one because it results in the highest pore-water pressure in the landfill and the smallest safety factor of landfill. Numerical results show that the safety factor of landfill reaches 1.016 after 746 mm rainfall with duration of 7 days, and the possibility of landside in Qizhishan landfill is very great.

Water injecting well backwash is one of the important measures to maintain normal production; backwash pressure is the main factor determining the efficiency of backwash well. Backwash process involves the coupling function of formation and casing under water pressure. In view of the backwash well pressure is based on compressive strength of casing. Three dimensional elastoplastic consolidation of rock and casing is analyzed by ABAQUS-6.5 finite element software. A fluid-solid coupling model is established to research transient responses of casing, formation and fluid during backwash, the coupling between casing and formation and fluid is realized; the change regulation of casing stress with anti-cleanup’s time is obtained. Numerical results indicate that the distribution of in-situ stress and formation property have significant impact on backwash pressure, which include formation elastic modulus, penetrating quality and horizontal in-situ stress. Casing and formation conditions should be taken into account for backwash pressure decision. Compared with the in-situ stress only considering the bearing capacity of the casing, the study results provide a more accurate theoretical basis.

Based on the finite beam element method, two kinds of whole bridge models of high-speed railway multi-span simply-supported bridge are set up. One is vehicle-bridge model including pile foundation, the dynamic impedances of the layered soil are presented, the improved Penzien model is used to simulate the soil-structure interaction (SSI); the other is vehicle-bridge model where pier bottom is consolidated without considering SSI; the seismic responses of the models are computed at different vehicle speeds, pier heights, earthquake strengths and earthquake waves. The calculation results show that the influence of the SSI on seismic responses of high-speed vehicle-bridge on soft foundation can not be ignored; the lateral displacement and acceleration of the bridge are influenced by low-frequency components, those low-frequency components interact with the earthquake wave incident from bottom side of the piles, which change the spectrum composition of the foundation movement, the frequency components which approach to bridge vibration frequency are strengthened; the lateral displacement and acceleration of bridge increase a lot after considering SSI; the vertical vibration frequency of the bridge changes little while considering SSI; the vertical displacement of the boxing girder increases little with the increase of pier height and vehicle speed; the high-frequency components which are caused mainly by the vehicle load and the track irregularity significantly influenced on the vertical acceleration of the boxing girder

In numerical simulation of geotechnical engineering, it is a priority to correctly select parameters, which reflects the real mechanical behavior of materials. Within the scope of particle flow code(PFC2D) as the particle discrete element method theory, a number of plane biaxial compression simulation tests are carried out for cohesive materials in the present study. According to peak axial stresses recorded under different confining pressures, internal friction angles and cohesions of specimens are defined following the Mohr-Coulomb strength criterion. After analysis of the simulation data, the relationship is interpreted between particle mesoscopic parameters of cohesive materials, including particle stiffness ratio of 0.5 to 10, particle bond strength of 0 to 50 kPa, particle friction coefficient from 0 to 6, particle bond strength ratio of 0.1 to 10, and material macroscopic shear strength parameters. The result shows that particle friction coefficient is logarithmically related to the internal friction angle of material; and particle bond strength is linearly related to the cohesion of materials. It is also noted that particles stiffness ratio and particle bond strength ratio have slight influences on material mechanical parameters; and the particle bond strength ratio significantly affects the shear failure form of the materials. Two final formulas are then established for the quantitative combined relationship between particle mesoscopic parameters and macroscopic shear strength parameters of cohesive materials after multiple nonlinear fitting. In these formulas, the proposal value of particle bond strength ratio is given for the mechanism of cohesive materials.

Limit equilibrium method with horizontal slice method is more suitable for layered soil slopes; but there are some deficiencies than vertical slice method. By studying the relationship of interaction forces between horizontal slice and vertical slice methods, corresponding assumptions of inter-slice forces between horizontal slice and vertical slice methods are established. And a combination model of horizontal slice and oblique slice is adopted when horizontal slice method encounters the sliding surface with toxoplasma. On this basis, the formulas of Sweden method, simplified Bishop method, simplified Janbu method, and Morgenster-Price (M-P) method for calculating factor of safety (FOS) are derived. Among those, two different FOS calculated formulas of Sweden method are obtained according to different satisfied conditions; and the general simplified Janbu method is improved based on previous studies. By using two types of sliding surfaces, arbitrary curve and arc, through analyzing some examples, the treatment of horizontal slice method taken in this article is verified feasible. At the same time, it also shows the results got by two Swedish methods are consistent; and the improved simplified Janbu method is better in analyzing stability of slope than general simplified Janbu method.

The refracturing technology has become an important means to develop the potential of old wells and stabilize or increase the production in oil field, while the reorientation mechanism and fracturing time are the key issues of restraining the stimulation effects of refracturing. This article makes the secondary development of ABAQUS finite element software platform, considers the dynamic evolution of rock porosity and permeability with the volumetric strain, achieves the overall coupling of fluid pressure change and physical property parameters, and makes the fluid-solid coupling analysis of reorientation mechanism of refracturing. The results show that stress reorientation phenomenon is common; the impact range of artificial fracture on the stress is limited which is not enough to form reorientation fracture; and the change of pore pressure is the major factor affecting stress direction; with the continuing progress of production, formation pressure and pore volume decrease, the change of volumetric strain of rock becomes slow, which makes the permeability decreases to a stable value; and the distance of stress reorientation increases and eventually turns to be stable finally; the greater stress differences, the more difficult the reorientation fracture forms because of little stress reorientation distance. This article realizes the visual depiction of stress reorientation in the condition of fluid-solid coupling; and the visual simulation is benefit for guiding the application and implementation of refracturing.

Using simplified k-??and mv-??models, the approximate solution for one-dimensional consolidation of structured soils under time-dependent loading is obtained by transforming structured soils into double-layered soils with the gradually changing thickness of the upper and lower layers. The rationality of the approximate solution is verified by compared with a numerical solution. The results indicate that different changes of the permeability coefficient and volume compressibility coefficient of structured soil after failure produce different results. Under a fixed change of the consolidation coefficient , the greater the permeability coefficient decreases, the greater the average consolidation rate in terms of stress decreases, while the greater the coefficient of volume compressibility leads to the greater decrease of the average consolidation rate in terms of deformation; the average consolidation rate in terms of stress is greater than that in terms of deformation; furthermore, the greater increase of the coefficient of volume compressibility yields an increased gap between them.