The consolidation behavior of cohesive soils has an important effect on the contaminant transport in a clay layer. In the current time the research on contaminant transport in deforming porous media has not yet begun in China; even in other countries this work only began some years ago. Combining Biot’s consolidation theory with the contaminant transport theory, a one-dimensional mathematical model for contaminant transport in clay layers is developed. The main feature of the model is considering the effect of soil deformation under loads on contaminant transport. The analytic solution of the model is then given based on some reasonable assumptions. Finally, the calculation results are compared with the results measured in a disposal site for the contaminated dredged sediments from the Taihu Lake. The simulated result has reflected the transport of contaminant in the actual soil layer.

A study on surface seepage effects on stability of borrowed soil in ecological slope. Stability tests of the soil without seepage and with surface seepage which use the same soil are carried out. It is found that the failure mode of the soil is a translational sliding surface parallel to the original slope surface along the upper surface of plane nets via stability tests with surface seepage; it is the same as the failure mode of stability tests without seepage. Stability tests of the soil with surface seepage testify that the charts, developed by YANG Jun-jie are effective. It is known from test results and theoretical analysis that stability of borrowed soil with surface seepage is remarkably reduced than that without seepage.

The behaviors of geomaterials before destroy can be reflected by the representative volume element; but when the high strain gradient occurs (such as the strain localization occurs), the representative volume element in which the strain and stress ate nonlinear, cannot reflect the mechanical character of geomaterials entirely. A plasticity gradient volume element (PGVE) which can describe the local deformation is proposed. The start-up mechanism of strain localization is analyzed; when the hardening modulus (or softening modulus) changes from positive to negative, the deformation pattern will change from uniform pattern to localization pattern.

dynamic canonical descent(DCD) algorithm is able to avoid being trapped by local optimization, and do not assume the cost function to be differentiable, if firstly given a appropriate convex space interval; the algorithm can converge to a least point which lies in the given convex space interval; the algorithm of global optimization is shown on the numerical experimentation and the application to the rock and soil project for back analysis; and it is proved that the new algorithm would converge to the global best point quickly with a good numerical stability and credible results.

Conception of limit soil-retained state was originated. Four kinds of woven steel-wire nets with different opening sizes were adopted in the filtration tests with silt. Test results show that filtration system approached limit soil-retained state when the ratio of the opening size of net filter (O) to the characteristic particle size (d85) of the silt upped to 12. Filtration system under limit soil-retained state kept stable during 26 hours of cyclic flow. And the filtration system still maintained its stability under the unidirectional submersed flow whose hydraulic gradient was increased from 3.8 to 9.1 gradually and maintained at 9.1 for 453.25 hours. Filtration system lost its stability under the unidirectional free flow whose hydraulic gradient was increased from 5.3 to 12.7 gradually and maintained at 12.7 for 261.83 hours. Researches on limit soil-retained state redound to a more reasonable upper limit of filter opening size and less clogging for filtration design.

Undrained triaxial compression tests were performed on these reconstituted samples of Nanjing sands at three different relative densities and the results of an experimental study are presented. All tests were performed under monotonic loading. It is evaluated and analyzed to the stress-strain relationship and the probability of the static liquefaction. At low densities, samples exhibited typical strain-soften characteristics, in which peak strength arrived when the axial strain was below 1%; then deviator stress decreased rapidly. Moreover undrained triaxial tests showed static liquefaction ( zone stress difference) at the confining pressure of 50kPa and 100kPa. As confining pressure were increased, static liquefaction disappeared and the effective stress paths indicated increasing resistance to liquefaction. Compared with Nanjing fine sand, clean sand, which has no fine granular, didn’t exhibit the static liquefaction at low confining pressure. So it is hypothesized that the presence of fines (particles smaller than 0.075mm) in the soil structure doesn’t bring out the notable changes of and, but provides the highly compressibility. At media dense and dense Nanjing sand show the strain-harden characteristics, and the slope of critical stress path arrives 55°with high resistances of static liquefaction.

A pile-cap foundation system is an effective way to support an embankment in order to minimize total settlement. Due to the higher stiffness of the piles in relation to the surrounding soft soil, the vertical stresses from the embankment are concentrated on the piles. Soil arching develops as a result of differential settlements between the stiff pile caps and the soft ground between them. The three-dimensional arches span the soft soil and the applied load is transferred onto the piles and then the firm-bearing stratum. This research was initiated from the Shanghai F1 speedway project. Shanghai F1 speedway has been built on the typical soft ground of Shanghai. The fill of Shanghai speedway includes not only the lime fly-ash which has been widely used but also EPS which aimed to alleviate the total load; piled embankments method is employed at the region where the height of fill is relatively high. The field test has been done in Shanghai F1 speedway to investigate the distribution of earth pressure on the cap and between the caps. In addition, numerical method is used to in comparison with the field test results. The results show that the earth pressure obtained in the soil right above the cap is relatively higher than in the soil surrounding the cap. And the earth pressure distribution shows the same way for the soil lies on the edge of cap and the centre of cap. The influence of EPS and piles character on soil arching is discussed.

Lower bound nonlinear programming model based on limit analysis theory is constructed through the analysis of limitation of linear programming models that are proposed by S.W.Sloan. The statically admissible stress fields for lower bound analysis are constructed by using nonlinear yield conditions; and the nonlinear programming models that can calculate overload coefficient and strength safety coefficient are established; and then the optimization strategy of nonlinear programming problem is put forward. Finally, a classic example of slope stability is given; and the results prove the correctness of the method.

It becomes more and more important to study and understand the deformation and strength properties of rocks to meet the increasing demands of deep mining and nuclear waste disposal. The paper mainly studied different temperature effects on deformation and failure characteristics of sandstone through meso-experiment. Experimental results indicated that the tensile strength increased with the temperature increment from 25℃ to 150℃, and decreased with the temperature increment from 150℃ to 300℃. The similar phenomenon has not been reported in the previous literatures. Also it differs with the most macroscopic experimental results. The paper analyzed the possible reasons in detail. Also the experimental results of macroscopic fracture map and nominal stress-strain curves indicated that the temperature had a strong influence on the deformation mechanism of sandstone. The fracture mechanism had the tendency which transforms from brittle fracture mechanism in low temperature to ductile fracture mechanism in high temperature.

Using the obtained parameters of field shear velocity test, static and cyclic triaxial tests, the finite element method based analysis approach is presented for the seismic stability of extended municipal solid waste (MSW) landfill, and the seismic stability of extended MSW along internal circular sliding surfaces, along interface between extended and existing MSW as well as along back and base liners is analyzed respectively by the finite element method. During the earthquake, the extended MSW more tends to be failure along the interface between extended and existing MSW if the water level of the leachate in extended MSW is low. For the dynamic stability of the extended MSW along internal circular sliding surfaces, the computed dynamic factor of safety of the conventional total stress method will be larger than the real one due to that is cannot take into account the softening of MSW induced by the increasing dynamic pore water pressure during the earthquake. The permanent diplacements of six landfills with different vertical and horizontal extensions are computed by the Newmark method for two kinds of input accelerograms with different maximal horizontal accelerations. Results show that logarithm of seismic permanent displacement of extended MSW along interface between the existing and extended MSW is roughly linear to the ratio of the yield acceleration and the maximal horizontal acceleration.

Based on rock engineering system (RES) theory, a full coupling analysis method and optimization design idea for the stability problem of underground roadway engineering are put forward. At first, the full coupling analysis method and flow are described briefly; and then collecting twenty-seven lithology samples. Global interaction matrix （GIM）of roadway had been made up by artificial network coding method; and the main influential factors and effect mechanisms had been analyzed. And then the stability evaluation parameters are proposed from the results of stabilization capability analysis; and the stability state ranges are given. At last, taking Shaqu Coal Mine for example, stabilization analysis and supporting optimization design are made; and the Q system is applied to appraise rock body quality for contrast analyze and validate the design result. All the results show that the full coupling analysis method has practical value for stability analysis and supporting design.

Disturbed soil is widely spreaded on the subaqueous delta of the Yellow River. It is different from the ambient undisturbed soil in many aspects. A sea area in the old Yellow River estuary is chosen as the study area. Geotechnical drilling and geophysical prospecting is processed to get the stratification and the geotechnical characteristics of the soil in this area. It turns out that compared with the undisturbed soil, the bulk density of disturbed is bigger, the void ratio is smaller, the water content is lower, and the shear resistence is higher. The limit liquefaction depth is calculated. The depth is coincident with the maximum thickness of the disturbed soil; and according to the statistics of the geotechnical factors, the abnormity of the soil is more or less limited in this very depth. The forming mechanism of the disturbed soil is discussed; and liquefaction during storm time is believed to be the controlling factor.

On the condition that the kinetic energy of coal shell in premonitory phase of its outburst is ignored; the equilibrium equation of spherical symmetric force of pore medium is established, which is under the coupling action of ground stages, gas pressure and effluent seepage. The character of spherical symmetry makes the strain Lode parameter at elastic and plastic stages is the same, and meet the condition of the physical relation of single curve. Popularized the uniaxial constitutive model, it can be educed that the relational expression between stress intensity and strain intensity of coal shell. It is discovered that, the educed expression of radial displacement u in elastic and plastic zones of coal shell, can be broken down into the displacement corresponding to deviatoric strain and the displacement corresponding to average strain. The energy analysis, which is carried through by using geometry equation, force equilibrium equation, physical equation and the relation of stress intensity and average stress synthetically, shows that the external force work change can be broken down into the external force work , and corresponding to deviatoric stress, mean stress and seepage stress; they are respectively corresponding to changes of strain energy of deviatoric stress, volumetric strain energy and pore volume energy; i.e. , . and The findings of two work-energy increment equilibrium relationship can be educed. It builds up the foundation for engaging catastrophe theory analysis of disintegration and outburst of a single coal shell in the outburst process.

The data of plastic geogrid such as yield stress, elongation of yield, tensile force relating to different tensile stretches etc., were obtained from the tensile test under low temperature. Through analyzing the test results, it is found that 1) The tensile characteristics of plastic geogrid enhance obviously under low temperature. 2) Under low temperature, the larger the cross-sectional area of ribbing is, the wider the increasing extent of tensile force is; while more obvious the decreasing trend of the elongation of yield. Contrarily, with the decreasing of the cross-section area of ribbing, the effect of temperature reducing on tensile force and elongation of yield is weakened gradually. 3) Compared with the unfrozen sample, the tensile characteristics change of the plastic geogrid suffered freeze-thaw cycling is not obvious.

Grouting used to heave ground is a common measure adopted to control the settlements of ground and buildings in underground constructions. Presently, designs of grouting are based on field-monitoring and construction experiences. The numerical simulation of the grouting effect is realized by advancing the parameters of soil property in the grouting zone, while ignoring the compensation effect of ground heave due to grouting. The relationship of the volume of grouting, the soil volume strain increment, and the value of displacement is established by a study on the mechanisms of soil expansion caused by grouting. A numerical method is applied to simulate ground heave caused by grouting. In the numerical modeling, a method is defined to calculate soil volume strain. It is proposed to increase the volume of the element by applying a “fictitious” expanding pressure in the element. And The process of injection modeling can be controlled by estimating the element volume strain increment to see whether it has reached the soil volume strain increment. The advantage of this method is that the expanding pressure can be a “fictitious” stress in the element, but not a real one of grouting. Contrasting the numerical solutions with the analytical ones, the numerical method is proved to be proper and available.

According to the Kelvin’s solution，considering three-dimensional stress state，the distribution formulas of normal stress and shear stress(that is, friction on the interface between the grout and the rock) along bonded length of compression type rock bolt are derived. Comparing with the in-situ experimental data, dependability of the formulas are proved. The stresses distribution along bonded length is analyzed with various parameters of soft rocks. This research offers a basis for the compression type rock bolts.

The general solution in the Laplace transform field for the consolidation of soil with partially penetrated vertical drains under complicated time-dependent loadings is derived. In order to consider the three-dimensional seepage in the soil beneath vertical drain, an imaginary drain in the soil just below the tip of actual one is assumed. And then by the Laplace transform the average degree of consolidation, excess pore water pressure and settlement of the vertical drain under arbitrary loading could be calculated. According to numerical examples, the influences of parameters of partially penetrated vertical drains are investigated; and by using the solutions, the approximate methods so far available for the computation of average consolidation degree of soft soil with partially penetrated vertical drains are compared and discussed in detail.

A hypoplastic model was investigated to describe the monotonic and cyclic behavior of gravelly soil. A new model was established through introducing the fundamental concepts of hypoplasticity theory and the critical state parameters. The formulae were derived; and their parameter determination method was also illustrated. The monotonic and cyclic stress-strain relationship response of a few gravels in practical projects were predicted and compared with the test results. The new model has few parameters, three-dimensional format and succinct formulae without loading criterion. The model is able to capture main monotonic and cyclic behaviors of gravelly soil, including the nonlinear relationship between the strength and confining pressure, the volumetric strain behavior dependent on confining pressure, contraction due to unloading and volumetric strain accumulation due to loading.

Underpinning is a new concept summed up from engineering practice in recent years; its principle is based on the relative position(distance) between the excavation and the existing buildings, the weight of buildings, soil engineering property, the probable destroy type and extension, with the load transfer and the stress transfer theory as the guiding ideology; designing to use less underpinning component to attain the purpose of anti-lean. The finite element analysis software package, Plaxis ver7.2, is used to study the underpinning excavation engineering. The anchor dead pressure piles are used to underpin the existing structure; and the finite element simulation is used to study the effect of underpinning on the force and deformation of the bracing structure. Through finite element analysis, it can be found that the distance between the excavation and the existing buildings and the thickness of the weak layer are important factor to underpinning.

Based on blasting vibration monitoring for the second phrase for Ling-ao Nuclear Power Station in Guangdong Province，the wave propagation characteristics under blasting in concave landforms are simulated with UDEC. It is founded that the numerical simulation results agree well with that by site monitoring. It is reported that the peak particle velocity (PPV) of blasting clearly decreased in concave landforms and the decreasing rate of PPV in horizontal direction is large than that in vertical direction. It is also reported that the attenuation coefficient increased with increment of depth and width of concave landforms; and the rising rates of attenuation coefficient with the width is less than that of depth. It is further suggested that the attenuation coefficient increases with increment of the charge weight and decreases with increment of explosive distance.

As a new type of deep-water offshore foundations, suction caisson foundation is widely used to fix offshore structure or facilities. Under such a circumstance, suction caisson foundations are frequently subjected to pullout forces. Therefore the ultimate bearing capacity and performance of such foundations under combined application of both vertical and horizontal components of pullout are one of the key issues in the design and construction of offshore structures and facilities. However, the performance of such foundations has been not well understood; and current methods of evaluation and design cannot meet the increasing requirement of engineering practice. Therefore a numerical procedure based on FEM for evaluating the uplift bearing capacity behavior of suction caisson foundation is developed. On the basis of the multi-purpose finite element analysis software ABAQUS, step-by-step loading procedure is numerically implemented to simulate the progressive deformation process and failure mechanism. During the pullout of caisson foundation, the normal consolidated clay is under fully undrained state. The general shear failure of caisson foundation is characterized by an ultimate collapse pattern due to bearing capacity which is opposite to traditional failure mode of foundation subjected to vertical compressive load. It is assumed that the soils surrounding the caisson foundations are in undrained condition during pullout and their original strength is fully mobilized. Then comparative numerical computations are performed for different aspect ratios of caisson foundation to determine the ultimate bearing capacity of caisson foundations under single action of vertical pullout or horizontal pullout. The authors’ numerical results are compared with the solutions obtained by current theoretical or numerical analyses. It indicates that the uplift ultimate bearing capacity by finite element numerical method is accordance with by theoretical method, and the horizontal ultimate bearing capacity has small variant.

Utilizing four kinds of limit equilibrium methods such as Morgenstern-Price, Ordinary, Bishop and Janbu, stability of the landslide No. 8 in Zhuxi sector of Taizhou North-to-South Water Transfer Project is studied on basis of reliability theory. Determined analysis schemes of most harmful, most favorable and mean constitutions are designed to set reference points for probabilistic method. The influence of cyclic number on Mento-Carlo method is discussed under condition of cyclic numbers of 5 000, 50 000, 500 000, 5 000 000. Then, the effect of probability distribution function such as normal, triangular and uniform is analyzed and tested. Furthermore, the effect of variance is reviewed on condition that standard deviation respectively equals 0.5, 1.0, 2.0, 3.0, 4.0 and 5.0 times of experimental value. Finally, sensitivity analysis and correlative coefficient between strength parameters from -1.0 to 1.0 change at intervals of 0.25 is considered. It is found that cyclic number only imposes great effect on extreme values of Fs, that different probabilistic distribution function and variance can do great harm to reliability indexes, and that correlative coefficient only exerts effect on failure probability.

It is important to research the relationship on the vehicle-terramechanics in lunar surface circumstances for the lunar rover to work according to schedule. However the regolith used in the laboratory test will greatly influence the precision and reliability of the test results. The regolith research based on the data of lunar soil specimen and the JSC-1 simulant lunar soil, the eruption is used as the basic material, and some hematite were added as regulator. Parameters of simulant lunar soil were measured, such as specific gravity, angle of internal friction, cohesion, grain size distribution, and mineralogy chemical composition. The results showed that parameters of simulant lunar soil in this test were close to the parameters of the lunar soil after adjusting grain size and proportion of added hematite sands. The simulant lunar soil could be used for the basic test of the terramechanics on moon in near future.

Displacement back analysis based on the in-situ measured information is one of the important parts that compose the dynamics measurement-control and information-oriented construction of the underground project. On the basis of measured displacements of surrounding rockmass , a system analysis method for back analysis of rock mechanics mechanical is established, which is used to gain the unloading surrounding rock mechanical parameters of the large-scale underground powerhouse (excavating span 30 meters and height 78.5 meters) of Pengshui Project on Wujiang River. The analysis method includes uniform design (UD) ，BP artificial neural network（BP-ANN）and genetic algorithm (GA) .Uniform design and numerical simulation are used to gain training samples of BP-ANN, and BP-ANN is used to simulate the relationship between rock mass displacements and rock mechanical parameters. In addition, the initial input weights of BP-ANN model are optimized by genetic algorithm (GA) because the initial input weights of BP artificial neural network model strongly affect the accuracy of neural network. And the rock mechanical parameters are gained through the trained BP-ANN and measured increment displacement of surrounding rock mass. Finally, the surrounding rock mass displacements induced by the excavation of underground powerhouse are forecasted. According the result, the forecasting displacements are approximate to the measured ones; so as to validate, the rightness and reliability of the above method.

The principle and process of the parallel seismic for the integrity of piles of existing structures is introduced. A 3D finite element model for the pile-soil system is established for impulse responses. Under saturated soil or unsaturated soil condition, some vibrating velocity-time histories at different depths in the parallel hole are obtained with the numerical model. It is shown that the length and 1D P-wave velocity of a pile are easy to determine from the features of the mentioned velocity-time histories. Results indicated that the PS method is a new suitable nondestructive test to evaluate the integrity of piles of existing structures.

The settlement of foundation with a cylindrically elastic inhomogeneity is researched. By considering the stress-deformation characteristic of the total field and applying the technique of series expansion, the appropriate stress functions are constructed; and accordingly the complex potentials of the rock mass are obtained. The numerical results indicate that to the different ratios of the shear moduli between the matrix and the inhomogeneity the settlement value of foundation boundary in some scope is greater than in the middle point of foundation base; and the value in other scope is less than in the middle point of foundation base. The results of the paper are enough accurate when the buried depth of the inhomogeneity is greater than 5 times of the radius of the inhomogeneity. As two special cases, the solutions for a circular tunnel and a rigid inhomogeneity in foundation are recovered.

Nonlinear FEM based on explicit time integration is applied to simulating the collision process of dynamic compaction. Many characters are taken into account, such as material nonlinearity, geometric nonlinearity, contact nonlinearity, movement nonlinearity and coupling characters of them, etc. The variation processes of collision force of hammer and deformation and stress of soil have been obtained at different heights, weights and areas of hammer. The analysis results indicate that the displacement of soil lags behind the stress of soil. The collision's entire process of hammer and soil and the common phenomenon in the dynamic compaction’s process has been reappeared.

Two moot dolphin platforms with bucket foundations were installed in JZ9-3 field of the Bohai Sea in 1999. This also was the first time in China to use the multi-bucket foundation to the platform．Though bucket foundation platform has been installed before, there is no experience in pulling up process of the multi-bucket foundation platform after long time use. The reutilization of buckets is proved in the pulling up test. According to the results, the analysis about the pulling up forces is given; and the results have certain effects to guide the construction procedure and the further study about pulling up forces.

Through the model experiment, the in-situ actual result and the theoretical solution of elasticity are compared each other; and it is pointed out that the theoretical solution of elasticity exaggerated the pile - pile, pile - soil, soil - soil interaction influence and created the predicted subsidence value to be big and overestimated the nonuniformity of pile head reactions (or nonuniformity of raft bottom foundation soil reactions). Finally, the solution way and method for revising the theoretical solution of elasticity ate pointed out.

Because foundation pit dewatering causes the readjustment of stresses in soil , it brings uneven settlements and architectural damage of the building around foundation pit; accordingly ,real time prediction of land subsidence caused by foundation pit dewatering has the realistic meaning; by using the theory of unsteady well flow and basic theory of soil mechanics, the real time prediction method of land subsidence has been introduced; the rationalities of different parameters in formula have been analyzed via case study; and it has certain meaning to forecast the land subsidence around foundation pit caused by foundation pit dewatering.

The tomography is a new nondestructive detection technique developed in recent years; it has special advantages of rich information, accuracy and visibility. So it has been playing more and more important role in detecting hidden danger of earth-rock dams. Based on the discussion of the theory of electrical resistivity tomography, a series of resistivity tomography nondestructive detcction tests has been carried out in Longfengshan Reservoir Dam. The seepage channels in Longfengshan Reservoir Dam has been found out; meanwhile, it has been approved that this method is reliable via applied to nondestructive detection in earth dams. The local tests indicate that the resistivity tomography nondestructive detection technique may be applied to detecting hidden dangers of earth-rock dams.

In the pumping tests to determine hydrogeologic parameters, the residual drawdown are considered more reliable because of the automatically controlled flow rate to the well during the pump shut-off period. Some strict limits and assumptions in classical Theis well function and Theis recovery method induce that it’s not suitable to practice. In practice, leaky aquifers are more and their flow to well will reach steady soon, while the pump discharge often is unsteady after begin. The discharge in the steady flow is substitute into Hantush-Jacob leaky aquifer model; then the extended Kalman filter is used to compute the parameters such as transmissivity, storage coefficient and leakage coefficient. Comparing with historical and in-site data indicates that estimated data match well with pump test data.

The compression modulus of sandy soil exerts influence on the stability of sandy soil surrounding rock of tunnel. From the perspective of influential factors of the stability of sandy soil surrounding rock and the stability classification of surrounding rock, the influential factors of compression modulus which are related to the stability of sandy soil surrounding rock, are explored. It is discovered that the clay content (d <0.074 mm) of sandy soil has distinct influence on the compression modulus of sandy soil; The relationship between the compactness and compression modulus is not always a direct ratio which is relevant to the clay content of sandy soil and water content of clay. It is held that it is more rational to adopt the water content of clay rather than water content of sandy soil to access the compression modulus of moist sandy soil. Recommended limits of content of clay and compactness for surrounding rock classification are advanced in accordance with the relationships between compression modulus and content of clay , compactness.

First, according to the basic equation of dynamics, using FEM and NEWMARK implicit algorithm, an elastoplastic numerical analysis is made to analyze the critical burial depth of hidden holes in loess under the roadbed subjected to the dynamic load (FWD). In order to reduce the effect of wave reflecting on artificial boundary, transmitting boundary and semi-infinite elements are respectively used to treat the lateral and underside boundary. Based on the numerical analysis, a regression analysis method using finite numerical results of critical depth is developed; and the calculation program "LDMC" is compiled. Finally, a validity check of the program is made;and it is shown that the result has relatively good precision and completely satisfies the needs of projects.

A new means of strain measurement of unsaturated soil specimen is introduced in suction-controlled triaxial tests based on digital image measurement method. The digital image measurement method can non-contactually and selectively measure the deformation of whole and local specimen and overcomes some critical shortcomings of using conventional strain measurement method for unsaturated soil specimen in suction-controlled triaxial tests. Meanwhile, the deformation process of the unsaturated soil specimen can also be recorded and analyzed after tests finished. The local deformation of middle section of unsaturated soil specimen that is relatively little influenced by end restraint can be handily and accurately measured by adopting the method. The deformation measurement results of unsaturated compacted soil specimens show that the end restraint has material effect on deformation of specimens and deformation characteristics of middle section is evidently different from the whole specimen that is influenced by end restraint in suction-controlled isotropic loading and triaxial compression tests. So the deformation measurement results of middle section can correspondingly really reflect basic deformation characteristics of unsaturated soil.

To protect the environment and reduce the water pressure on lining as possible, the controlled drainage principle is proposed in high water-level mountain tunnels. But there is no specification for tunnel design with controlled drainage, so it is very urgent for tunnel design and construction. The mechanical character of the surrounding rock under coupling of seepage and stress is studied based on tunnel mechanics and seepage mechanics. The interaction between surrounding rock and lining with different drainages is studied by using character curve method; and the result is compared with numerical method. The result shows that the character curve and the support force are different and the effective tangential and radial stresses vary remarkably with different drainages; so the effect of drainage on the stress of surrounding rock and the support force can’t be ignored. Another conclusion is drawn that it is unsafe in traditional tunnel design that action of water is not considered during total drainage. All these conclusions can provide theoretical base for tunnel design with controlled drainage.

The microstructure and pore characteristics of natural loess and CO2-silicification loess are qualitatively and quantitatively studied based on the test results from scanning electron microscope and digital image analysis and accelerated surface area-porosimetry system. The silicified loess samples have been curing for 13 years, 19 years and 24 years respectively. It is found that the main structure type of CO2-silicification remains the same as that for the natural loess. the silicate gel and calcium(magnesium) silicate gel have only filled in the pores and adsorbed the surface of frame grains resulting in increase of contact area of frame particle. Being compared with natural loess, CO2-silicification loess isn’t reduced in pore size distribution and average pore diameter and area porosity and pore volume; the pore surface area of CO2-silicification loess has been increased from 17.8104 m2/g to 27.4735 m2/g. CO2-silicification loess mechanism is that the open structure in silicification loess remains, but a film of gels reinforces the bond strength of cement in microstructure and forms three dimensional networks of frame grains resulting in the collapsibility of silicification loess disappearing; and mechanical properties of silicification loess are improved.

Low-permeable abnormal high-pressure reservoirs own some characters that elastic energy is abundant, and reservoirs are under-compacted, and rocks are prone to elastoplastic deformation. According to these features, an approximate relationship of final recovery and petrophysical property based on Darcy’s law is achieved; and the concept of permeability variation factor is introduced to analyze the affecting factors on recovery rate. Taking West Wen-13 block for example, exploitation methods of such reservoirs are analyzed and discussed by means of permeability variation factor, combining with pressure sensitive experiment of different fluid permeability, experiments of permeability change in different pressure loading modes, and depressurizing elastic drive and water flooding experiments. The results show that a higher oil recovery can be obtained by maintaining slower depressurizing speed and higher pore pressure.

The method of the stability calculation of landslide with pore pressure is presented and an amelioration for the imbalance force method is done. A three-dimensional numerical simulation with FLAC3d has been carried out for a landslide of a hydropower station to study the pore pressure, phreatic level and flow discharge, which affected by the subhorizontal drainage holes, during the drainage period. The research of the stability change of the landslide is accomplished by the amelioration imbalance force method with the data achieved from the simulation results of FLAC3d with a program written by FISH language. The results indicate that the procedure of the stability expansion is represented properly by the amelioration method. The degrees of increased stability and the decreased imbalance force are underestimated with normal methods during the drainage period.

The mechanical model of circular layer-crack structure of coal heading face is established with the simplification that the laneway is circular. Based on the expression of total potential energy function, a fold catastrophe model of circular layer-crack structure is established; the sudden change condition of gas outburst is given. The research results indicate that the coal and gas outburst will happen if pressure drop of the two sides of plate is larger than critical value. This research result is useful for gas outburst prevention.

In order to study the seepage law and influential factors of flow in double porosity medium in the pore-fractured low-permeability reservoir, the dual-media cross-flow mathematical model is established and its solution is given. By numerical solution, the pressure dynamic characteristics and effects of storage coefficient and interporosity flow coefficient on pressure response are researched. By pressure-sensibility experiment, the effect of effective stress on percolation ability of double porosity medium low-permeability reservoir is studied. The study shows that the larger storage coefficient is and the later happening interporosity flow time is, the smaller interporosity flow coefficient is the larger interporosity flow pressure is. Permeability and porosity decrease when effective stress increases, which changes storage coefficient and interporosity flow coefficient and effects pressure dynamic characteristics. So keeping pressure and protecting reservoir are important for developing the pore-fractured low-permeability reservoir.

In connection with slope stability of soil nailing support for foundation pit, the authors discuss the shortcomings of limit equilibrium method and indicate that the FEM stability analysis is new trend to evaluate the stability of foundation pit. The slip surface stress analysis method and strength reducion method are used to analyze the stability of soil nailing support for foundation pit. For the slope without supporting foundation pit, the results of safety factor and critical slip surface obtained by two finite element methods are consistent and the shapes of critical slip surface keep sameness with the reduction of strength parameters with soil. For the slope with soil nailing support for foundation pit, the safety factors by two finite element methods are consistent; but the shapes of critical slip surface are inconsistent in different stages. The reason is that only the strength of the soil and the cement deep mixing pile are reduced during the process in the calculation; and the strength parameters of the nail bar are regarded as constant. Finally, the authors indicate whether or not considering the reduction of soil in strength reducion method with FEM waits for further research.

A numerical simulation method of drainage hole in three-dimensional seepage field in underground engineering is presented according to the theory of seepage flow. Drainage holes are implicit in model and their data are gained according to pre-process. The relative positions of drainage holes are judged and their impacts are simulated through modifying the penetrability conduction matrixes of elements perforated by the drainage holes. And then drainage substructure method and implicit composite element method are compared via an example. Finally, a three-dimensional finite element method calculation program compiled by ourselves is used to simulate the seepage field of an underground hydropower house. The calculation result shows that the new method introduced is feasible to simulate drainage holes.

To cut a bedding high rock slope, usually it is necessary to take some reinforced structures in advance. How to determine the range of disturbed zone properly is a core problem. According to the stress condition and displacement condition after cutting a slope, the disturbed zone can be defined. Taking the bedding high rock slopes of Wanzhou-Liangping Expressway for example, mechanical properties and influential factors of disturbed zone are introduced. In addition, the disturbed zone of bedding high rock slope is studied on the basis of rock mass structure. It is most unstable when the inclination of rock stratum is between 15－30°; also there is a relation between length of disturbed zone and depth of cutting. The results show that the ratio of length of disturbed zone to depth of cutting is situated in between 2 and 5 to most sandstone and mudstone bedding high rock slopes.

Through large numbers of geotechnical tests, the correlativity between liquidity index and natural water content, natural void ration, natural density, modulus of compressibility, coefficient of compressibilty, cohesion of silty clay in the subgrade of Su-Tong Bridge Engineering at lower reaches of the Yangtze River was studied, regression equations were given, and the comparison of correlativity curves with other areas in China was also presented. It was found that the correlativity between liquidity index and natural water content, natural void ration, natural density, coefficient of compressibilty was linear, and the correlativity coefficients were over 0.92; the correlativity between liquid index and modulus of compressibility, cohesion is exponential, and the correlativity coefficients were over 0.87; there were better comparability between regression curves of silty clay in Su-Tong Bridge subgrade and regression curves of silty clay in other areas’ subgrade. The following conclusions can be drawn that these regression equations in this paper can provide important reference for silty clay in analogous subgrade.

The simulation method of rock mass joint network is studied. The randomness of geometric parameters and mechanical parameters of joint is taken into account in the generated joint network. In order to determine the representative element volume (REV) scale of rock mass, an index is defined by use of the generated joint network. On the basis of the above analysis, the codes for joint network simulating, for network plot outputting and for REV scale analyzing are developed. The rational analysis of the research results and codes is carried out through a case study. The results of a case study show that the REV scale is about three to four times of the maximum expected value of trace length of rock mass joints sets. The research results offer a basis of computation of rock mass equivalent mechanical parameters.

The paper points out that incidence function of matter-element extension model is not convenient to calculate, and mutual exclusion of indexes has not been solved; so it has an influence on applied range of matter element analysis method. By constructing a new interval incidence function, matter-element extension model has been improved., and solved mutual exclusion of indexes. The method is convenient to calculate, and widen applied range of matter element analysis method. It has been applied to determine expansive scale of expansive soils; and its reasonableness and effectiveness have been proved.

Based on reviewing three-dimensional geographic information system (3D GIS) technology, an information management and prediction system for urban land subsidence is designed on the basis of GIS technology. The detail of design thought, function and structure of the system is introduced. The authors proposed a series of blue print for key problems when constructing the system, such as the principle for choosing land subsidence modeling based on porous water migration, the process of 3D land subsidence modeling and its volume visualization supported by the mixed data model and three layers structure for the information broadcast function of the system through Web, etc.

The G23 mylonitization and fractured belt located in the dam-foundation of a hydropower station is a main engineering geological problem of the project. Its genesis mechanism has been analyzed based on the characteristics of the new tectonic movement and the tectonic system. With the X-ray diffraction and scanning micrograph analysis, the main mineral components and microstructures of either the fractured rock or the phyllonite are identified. With the conventional triaxial compression testes, the stress-strain characteristic of G23 belt rock is examined. In conjunction with site specific analyses, the pre-existing state of rock mass in G23 belt is expounded. At last, based on physico-mechanical properties, the mass rock’s engineering characteristics are estimated; the influences of the G23 belt are discussed; and the main problems which should be study further are put forward.

Post-grouting technique has a wide range application to piled foundations. The principle of post-grouting technique is as follows: through grouting cement into bottom of bored pile or around pile body, the loose material such as deposit and slime during pile construction can be strengthened; and it can highly increase frictional resistance and end bearing capacity of pile. Post-grouting technique was successfully employed in the piled foundation of Su-Tong Bridge, a huge bridge under construction which connects Suzhou City and Nantong City in Jiangsu Province, China. According to the results of static load tests, the U-shape grouting pipe was used in the project for the piles’ bottom grouting. After grouted, values of the ultimate bearing capacity of the tested piles were increased up to1.48-2.0 times the ones of un-grouted bored piles. For end bearing capacities, their values were increased up to 2.46-7.21 times. It can be drawn a conclusion that through using post-grouting technique, it saves investment, improves construction quality and reliability, and brings considerable economic benefits and well social environment effects as well.

The excavation of foundation pit involves both horizontal and vertical unloading processes. In order to investigate influence of each directional unloading on displacement and internal pressure of the retaining structure, a foundation pit is analyzed via the FEM simulation of the corresponding modified Duncan-Chang model, under respective unloading of horizontal or vertical pressure. It is shown that the horizontal displacement of retaining structure is largely caused by the horizontal unloading; while the vertical unloading is responsible for the negative internal force. Consequently, this study provides an explanation about the often-observed fact that measured internal pressure in the field is always lower than the one expected in the design.

Firstly, an assumption that the compressibility curve of soft soil fits in with the hyperbolic equation is adopted; and it is validated by a series of data in a certain project. Since there are only a few parameters of hyperbolic equation,it is simple and feasible to use data fitting.Thus a simplified calculation can be introduced to the practical calculation of soft soil foundation and meets the accuracy requirement of a project.And then under the circumstance of not having adequate e-p experimental data in a geological report, a simplified approach is put forward to determine parameters of e-p hyperbolic equation with initial void ratio e0 and compressive modulus Es. Finally, based on the above-mentioned method of e-p curve, we acquire tangential modulus(Et) of Duncan-Chang model and with the Layer-wise Summation method(LST) apply it to the nonlinear settlement calculation of soft soil foundation. By comparing the tested settlements with the calculated ones, it is shown that the simplified method is capable and practicable.

Based on researching the collapse cause of an industrial building, it is concluded that the main cause is pile foundation’s lateral displacement induced by soil pressure, which is transferred to pile body due to soil arching action between piles. The accident proves that the soil arching action indeed exists between piles. Furthermore, three-dimensional numerical model is established to explore soil arching action of passive piles; the comparison is made for the differences of soil arching action between three dimension and two dimension; the rule is drawn for soil arching action of passive pile under different pile spaces and different loads; and the variation rule of soil arching action with time is explored.

Based on the exponential trend model, the Kalman filter model is applied to forecasting displacement values at observation point in Lianziya hazardous rock mass GA. At first, nonlinear exponential trend model is linearized into linear model; and linearized model parameters are obtained using the linear least square method; the linearized model parameters are regarded as state vectors containing dynamic noises to erect Kalman filter model. On the basis of Kalman filter model, the displacement values of the hazardous rock mass are forecasted. An example of calculation shows that the forecast error is little and the forecast effect is good using Kalman filter model to forecast the displacement values of the hazardous rock mass .

Some problems such as fuzzy physical meaning, imperatively discerption of resistance and action involved in the wedge stability analysis method specified in the Gravity Dam Design Code（DL5108－1999）, are put for ward, based on introducing the destruction types of deep slide of gravity dam and rigid equilibrium limit method. And the reasonable expression of analysis presented in this paper is not only very clear but also the result is apt to safety through a practical engineering example.