Among a lot of factors participating in the saturation progress of buffer material in geological disposal for high level radioactive nuclear waste, the initial head, permeability and saturation degree are the most keys. The author uses a 2 D FEM code for coupled thermohydromechanical phenomena to analyze the influence of the three factors mentioned above on the saturation progress of buffer material. From the results it is known that the bigger of the values of the initial head, permeability and saturation degree is, the faster of the saturation velocity is; and vice versa.

The geogrid-reinforced earth retailing walls have been widely applied to geotechnical reinforcement constructions. A viscoelasto-plastic model is employed to consider the rheological properties of backfills and foundation soils while the empirical nonlinear viscoelastic model proposed by the authors is used to take the creep behaviour of geogrids into account. The numerical analysis procedure based on finite element method is developed for evaluation of stresses and deformations of geogrid-reinforced earth retaining walls under long-term loading. The comparative computations are conducted to examine the effects of construction process, geogrid length and spacing on long-term performance of geogrid-reinforced earth retaining walls. It is shown that the filling process have a considerable influence on the lateral displacements of panel, pullout forces and strains of geogrid and horizontal and vertical deformations of foundation The geogrid used for reinforcement will induce the redistribution of stresses in backfill. Both rheological effect of soils and creep effect of geogrid seem disappear after a certain period.

Based on the cutting experiments used by cutter tooth and point-attack pick on the press and cutting simulation test table, the deformation and failure process of coal body are studied by the method of white light digital speckle correlation. The results indicate that a stable deformation localization band occurs in the coal cutting course and develops to macroscopic crack; the deformation localization band is slantwise; while the cutter tooth is used, the deformation localization develops slowly, and the localization becomes wider and the strain value in the band area higher afterwards; when the point-attack pick used the localization develops quickly and the localization band becomes narrow and the strain value in the band lower. Finally, the authors draw a conclusion that the main failure of coal body is shear failure under the action of cutting.

As a type of gas or oil storage, salt-cavern gas storage has been adopted widely in developed countries. With the development of Gas Transmitting From West to East Project and natural gas industry, large numbers of gas storage will be built in China, so it is important to analyze the stability of salt cavern. The stability and creep of salt caverns #1 and #2 in Jintan Salt Mine are simulated by the famous finite difference software FLAC3D; and the results show that volume reduce ratio of salt caverns is within 22 percent as running pressure of gas storage between 6 MPa and 14.5 MPa, which can give guidance to build and management of gas storage.

Based on test of physio-mechanical properties of the overconsolidated soils near the depression cone of groundwater in Haikou City of Hainan Province, it is found that the seepage and deformation of the saturated overconsolidated clayey soils can take place under the additional stress. The lab test results show that the sustainable exploitation groundwater level can be determined by the deformation characteristics of the compressive curves. The research achievements are of great significance for the reasonable exploitation of groundwater and for the control and prevention of the land subsidence and relevant geological hazards.

In order to reflect the influence of complex geologic faults in large underground chamber, the authors put forward a numerical simulation and analysis method for the connotative fault element. The method establishes an equivalent element comprising both rock material and fault material, which can decrease the influence of faults incision. By this way, not only the mesh generation of large underground chambers becomes relatively convenient and feasible, but also the influence of complex geologic faults on stability of surrounding rocks is reflected effectively. At last, a sample about underground chamber of Three Gorges Project is given, which testifies that the method is reasonable and provides an effective computation method and train of thought for the analysis of complex geologic faults structure.

Based on the prototype of the representative geological section plane of a copper mine, the physical general model test is made to analyze deformation and subsidence of ground surface and surrounding rock with different excavating steps by grid digital photography which is used to measure full-field displacement of model section plane. In the model test, once mines between –75m and –45m are excavated; the influence zone of surrounding rock and the subsidence displacement of surface become greater and greater. Thus, the rocks above the cavity begin to separate from surrounding rocks after the 7th excavating step and the zone from No 1 testing point to No 4 testing point form a subsidence basin obviously after the 9th excavating step. The result of model test is almost consistent with the result of UDEC( The Universal Distinct Element Code) and the in-situ circumstance.

Assessment on stability of partial rock-block mass is essential during tunnel’s design and construction. On the basis of geological sketching explosion views, combined with projective geometry and the block theory, simple geology-geometry analytical procedure simplifies geometrical analysis of critical rock-block mass so as to define its space location, geometrical forms, different type of collapse or slippage, stability factor of single sided or double sided slippage, thus directly instructing purposive reinforcement of tunnel surrounding rock mass promptly. Finally, on the basis of geological sketching explosion views, this new simple analytical procedure is firstly applied to assess the stability of partial critical rock-block mass of tunnel Manxie 3; and a conclusion that plump collapse is the main destructive manner of critical rock-block mass is drawn. It not only assures the safety and continuity in the course of tunnel’s construction, but also has been testified having anticipated good effect in actual geology engineering application.

3D-FEM computation model included 41 items large structural planes and 5 items faults in the real attitude and distribution in the No.3 dam foundation and No.4 dam foundation of left powerhouse of the Three Gorges Project combined action are created. The safety factor of No.3 dam foundation in deep sliding stability due to No.4 dam foundation combined action is studied. A new practical judge method of dam foundation stability safe factor based on 3D-FEM simulation results using strength reduction method is proposed; it has definite physics meaning. It shows that the combining action of No.4 dam foundation can increase the safety factor of No.3 dam foundation; but its effect is small.

Slope engineering stability is affected by lots of reasons and the load possesses uncertainties, which can be expressed by the upper and lower boundaries of an interval variable. The interval finite element method, which is combined by interval mathematics and FEM, is proposed to solve the deformation of slope. Taking Gushubao landslide as an engineering case, the practicability of interval finite element method is investigated. The numerical results gained by interval finite element method are compared with that by conventional finite element method, of which the case results show that the method applied to the engineering of the loading uncertainties and mechanical parameters uncertainties is feasible. Compared with conventional finite element method, the interval finite element method is more convenient and simple but the computable results are more suitable to calculate the loading combinations of slope.

The compaction character experiments under different compaction degrees showed that the CBR value increased with the filling compaction degree increasing; the filling is provided with nicer compaction property, so it can be used for highly weathered soft rock to fill high grade highway embankment. Triaxial shear apparatus with an approximate actual stress path was used to do dry-wet crewel parallel experiment and wetting deformation experiment of different compactions under complicated stress function. The result shows that crazing and plastic destruction will not take place on road surface when the critical strain value is 2 %，the slaking deformation is reduced with compacting factor of the samples increasing and the shear swelling deformation is increased with deviator strain increasing when ? 3 equals to 200 kPa. Testing results are applied to subgrade embankment of the Zhaoshan Road in Xiangtan city, and construction measures of the embankment of clay in 95 area, wetting embankment and increasing compaction degree of the filling in 90 area are put forward.

The expansive potential of expansive soils is decided by many factors. It is a multi-factors evaluation problem for classification of swelling-shrinkage grade of expansive soil. The theory of adaptive-network-based fuzzy inference systems (ANFIS) was introduced and subtractive cluster method was applied to deciding fuzzy inference rules. After that, an ANFIS was proposed and applied to two engineerings. Good results were obtained for many test examples. It is concluded that ANFIS can function as BP neural network and fuzzy comprehensive evaluation on classification of swelling-shrinkage grade of expansive soil; and moreover, ANFIS is clearer than BP neural network in network structure and possesses of self-study ability compared with fuzzy comprehensive evaluation. The application of ANFIS on classification of swelling-shrinkage grade of expansive soil is feasible.

There are some reasons to engender the rock-burst such as the rock post-peak behavior, which is the radical reason, and geological factors, which are exterior. After analyzing the energy releasing and gathering and transferring in surrounding rocks during the excavation in underground projects, it is discovered that the high stress is one of the important factor to engender the rock-burst. Character of engendering the rock-burst in space-time appears in step of plastic intenerated deformation. And the conditions of rock-burst are studied with nonlinear analysis. So the results are that the stability of the rock is connected with the size of the rock and physical characteristic of demolished rock. And the criterions are following the equations, and < .

The geological conditions in Xiang-Lin Road in Yunnan Province are complex with poor rock quality, far-ranging slopes and numerous clayey gliding mass containing much reduced stones.The test data of this kind of gliding mass are analyzed by the random statistic method and random-fuzzy method. The density function of the shear strength about the gliding mass is worked out firstly. Then the shear strength of the representative slope is acquired in four different ways. At last, the comparison is made between the statistic results so as to get the best indicator.

By use of medium scale dynamic triaxial apparatus made by Earthquake Engineering Research Division, Dalian University of Technology, the development of axial strain and pore water pressure in sand-gravel composites during liquefaction is studied experimentally. At the same time, using DS-2T dynamic triaxial device scalping the oversized gravel particles and taking similar gradation method, a series of parallel tests proceeded. The development of shear strain and pore water pressure of sand-gravel composites and substituted material due to cyclic loading were compared. The results show that with isotropic consolidation, the development of dynamic pore water pressure in sand-gravel composites differs from that in substituted material and its curve can be fitted by corrected arcsine. However, the pore water pressure curve in substituted material can be fitted by arcsine function. The maximum value of dynamic pore water pressure in both of them can not reach the initial effective confining pressure. Also, the response of axial strain in sand-gravel composites is variant from that in substituted material and it increases steadily during cyclic stress action. The development in substituted material is not appreciable before initial liquefaction; when pore water pressure reaches its maximum value which is considered as the liquefaction standard, once initial liquefaction occurred.

The limit state function in the reliability analysis of geotechnical engineering is often very complicated or even implicit, so it’s difficult to calculate the limit state function’s gradients analytically. However, the solution of the gradients is necessary and important in some general used reliability analysis methods, such as the first order reliability method(FORM) and the second order reliability method(SORM). Therefore, it’s necessary to solve the gradients of the limit state function by numerical methods. The authors studied carefully two numerical differential methods, finite difference method(FDM) and rational polynomial technique(RPT), and pointed that FDM is the special case of RPT when the limit state function is linear. Accordingly, FDM3 can be used for the continuous linear limit state function and RPT5 for the continuous nonlinear limit state function. For the discontinuous limit state function, RPT should be used because of the large error of FDM. In each case, the control coefficient of step size is suggested to be 1.

The secondary pollution from sludge is reduced as a result of the lower permeability of sludge treated by the S/S(solidification and stabilization) treated. However with the change of the biochemical condition of the environment, the permeability of solidified sludge will change as well. To evaluate the environmental impact, the biochemical condition of solidified sludge was enhanced; and the permeability test with acid and nutritional filtration liquid was performed on the solidified body. The experimental results showed that increasing the solidification level would lower the permeability of sludge, but the permeability will be increased under acid condition. The permeability change of solidified sludge was not only decided by the total infiltration volume of infiltration liquid but also controlled by the strength of acid; and microorganism activity could remarkably decrease the permeability of solidified sludge.

The microstructure and pore characteristics of natural loess and roadbed loess improved by impact compaction after 8-40 compactor passes were qualitatively and quantitatively studied on the basis of the test results from scanning electron microscope (SEM) and mercury intrusion porosimetry(MIP). The results show that open structure is the main structure type of natural loess and roadbed loess after 8 compactor passes; and inter-particle inlaid structure is the main type of roadbed loess after 16-40 compactor passes; The pore size distribution is within the range of 0.006~164 μm before and after 16 compactor passes, the average pore diameter has been lowered from 0.767 9 μm to 0.071 1 μm; the median pore diameter has been decreased from 5.264 μm to 0.5684 μm. The pore surface area has been increased from 0.624 m2/g to 7.517 m2/g; there are two dividing pore diameters of 10 μm and 2 μm for all types of loess, and for the loess before 16 compactor passes, the pores with diameter between 2 to 10μm cover 67.53 % of all the pores, while the pores with diameter less than 2μm cover 68.07 % for loess after 16 compactor passes. Therefore the optimum compactor pass is 16 and the improvement mechanism of impact compaction is change in loess microstructure and increase of micropores.

Based on the mechanical test and the Norton Power law of salt rock, a new constitutive law of salt rock is presented. The new constitutive law can embody the steady creep and the accelerative creep of salt rock by importing the damage variable. The damage equivalent stress is the function of confining pressure and deviatoric stress in the new constitutive law. The parameters of the constitutive law were obtained by simulating the experimental data of salt rock in some salt mine. The theoretic results accord with the experimental results. By the three-dimension numerical method, the new constitutive law is programmed. The natural gas storage in the salt mine is analyzed by the new constitutive law. The evolvement law of damage bound and the displacement law around the natural gas storage is studied under the minimal natural gas storage pressure. The continuous operating time of the natural gas storage is also analyzed under the pressure. The study indicates that: (1) The presented constitutive law has good numerical stability during the accelerative creep. (2) The extension of the damage bound around the storage is very fast after the salt rock around the storage enter the accelerative creep phase under the minimal operating pressure. The most dangerous position of the storage is the top. (3) The steady volume convergence becomes steady and the damage creep volume convergence develops very fast after the salt rock around the storage enter the accelerative creep phase. (4) The continuous operating time of storage can’t exceed three months under the minimal pressure.

The slope stabilized by single-row piles is simulated by nonlinear finite element method with shear strength reduction. The piles are laid out at variant sites on the slope surface, whose spacing is four meters each. Conclusions are made that factor of stability, the location and shape of the slide surface vary as pile location varies. Pile location variable determines whether slide comes from anterior surface of the pile or from posterior surface. One critical principle for the option of pile location is that the factor of stability on landslide control is greater than the factor of safety to meet with design expects, else slide will originate from pile head or from anterior surface of the pile. Under the same factor of stability, the lateral force, internal forces such as shear force, moment and deflection of the pile vary with pile location variable. The length of the pile is longest and the lateral force is largest when the pile location is in the middle of the slope, so it is not desirable location for the pile. But the deflection and resisting force responded are largest. The lateral forces on the normal method and the method of finite element are equal for the pile that there is no soil mass in the front of pile. The lateral force is reduced when the pile as beam element is located in the body of landslide, because resisting forces supplied by the soil mass in front of the pile are taken into account.

The no-smoothness resulting from changes of contact state is the main reason of nonlinearity in contact analysis; but this no-smoothness can be approximated by constraint function; and then Newton method or Newton-like methods can be used to acquire its approximate solution. The conventional Goodman element is the most frequently used model in the numerical simulation of structural planes; but there are some difficulties in parameter determination and computing convergence. By constraint function method, the conventional problems in Goodman element can be solved easily. The detailed format of its finite element method is given; and then a simple method dealing with rigid displacement is also given. Finally, combined beams and dam foundation #3 of the Three Georges Project are computed as examples.

Using definition of damage variable, a method for engineering application is put forward; and it not only reflects real mechanical course, but also obtains and measures its value readily and objectively. The definition of relative damage is brought out. The degree of damage expansion and relative damage of different parts when the damage material under blasting action could be expressed with it, and the determination of damage variable which measures the degree of loading is easier. At the same time, based on crack expansion, a computation method of damage cumulation is suggested.

The function and process of ANSYS, a large software, are elaborated. Based on the materials which we got from the practical investigation about the dam, used ANSYS to analyze and numerically simulate the major dam of the Forth Tailings Deposit in Fuxin Electric Power Plant. Based on it, displacement, deformation, all sorts of equal stress and the region of cracks and crushing can be drawn from the analysis of the dam. Based on the useful information, it put forward the suggestion on future work. And the factory can take timely action during the time of the dam operating.

Combinating the typical engineering geology characteristics and the typical example, the method of calculating settlement of handling the soft soil roadbed by DJM piles are discussed; and on the basis of settlement control and analysis, the project of design use DJM pile to handle soft soil roadbed was chose optimally, especially the pile length choice and pile distance choice are discussed. And the different design schemes based on settlement control were analyzed and compared; some physically and very beneficial conclusion are drawn for using DJM piles to handle the bridge head roadbed and curing the automobile bouncing on either end of bridge etc.; and they have the direct leading meaning.

The interaction of soil and pile is analyzed by ANSYS; and the state of stress and strain in the soil after the pile was driven in is simulated. By combining the contact analysis with birth - death element of ANSYS, and proposed the soil material comply with the Drucker-Prager criterion, the circulation command is used to analyze complicated soil stress state. These results are verified by limit equilibrium method and theory of expansion of a cavity.

Forecasting of the blasting vibration is always the premise and basis of the controlling of the blasting vibration damage, and is an important subject of it. Based on the numerical simulation method of finite element, the calculation method of particle vibration velocity, an important index reflecting the blasting vibration intensity, is discussed; and an comparison analysis of the calculation results between two different kinds of charge structures decked with air and water is made. Numerical simulation results indicate that the calculation results are correspondent with the actual results if the distance from the blasting center is not far; it has certain significance to the design and construction of blasting.

The problem of earth pressure is studied by using the limit equilibrium variational method and the Culmann analysis method. In the limit equilibrium variational method, the problem of active earth pressure and passive earth pressure is formulated in terms of calculus of variation based on the two force equilibrium equations of the sliding mass, and is transcribed as the functional extreme-value problem of two undetermined function arguments by means of Lagrange multiplier. According to Euler equations that must be satisfied when a functional attains its extremal, the conclusion that the failure of soil mass behind wall is in the mode of sliding on a plane surface is drawn when the active earth pressure and the passive earth pressure get the minimax solutions. In the Culmann analysis method, the assumption that the soil failure is in the mode of sliding along a plane is adopted; however only one force equilibrium equation along some special direction is utilized to derive the computation formula of earth pressure. Compared with the popular proof process of the Coulomb earth pressure theory, the Culmann analysis method is more simple.

The stress field induced by waves in seabed is calculated on the basis of Biot’s two-dimensional consolidation theory. On the assumption that cohesive force of seabed soil isn’t associated with wave action, a criterion is proposed for discriminating wave-induced failure in seabed of feebly cohesive soil or silt; and it enriches traditional discriminant methods. Moreover, with a detailed discussion about influence of cohesive force on failure depth of seabed, the criterion is applied with ideal results to analyze the stability of seabed in the sea area of Chengdao Oilfield, the yellow River Delta. In the analysis, influence of cohesive force of soil on failure depth of seabed induced by waves is discussed under two oceanic conditions (with occurrence periods of 50 and 5 years). Calculation results show that the cohesive force of soil has a prominent influence on seabed stability.

The long-term settlement behavior of multi-story buildings on soft clay foundation in Shanghai is analyzed based on the long-term observed data of 50 multi-story buildings. Exponential model can reflect creep deformation of soft clay, which has obvious physical meaning of rheology. The long-term settlement of building is simulated well by analyzing the observed settlements after construction with the exponential model; and the final settlement and settlement duration are predicted. Considering the variation of thickness ratio (Ks) of very soft clay layers in the four types of subsoil, relationship between Ks and long-term settlement of building is obtained from analysis of all records. With the increase of Ks , the final settlement and settlement duration increase, while the ratio of settlement finished during construction is decreasing.

The extent of soil disturbance induced by shield tunneling construction is analyzed. It is considered that the assumed boundary condition of ground loss in Loganathan’s formula exists error based on the principle of limit equilibrium. The influence of internal friction angle on ground movements is taken into account. It is considered that the level obliquity about boundary line of the vertical ground formation region should be (45°+? /2), but not 45°. The modified Loganathan’s formula is presented, which is only applicable under the undrained condition in clays. At the same time, the calculation for the extent of the cut disturbance of shield is advanced for the first time. As shown by analytical calculation for a project case, the proposed new approach tends to decrease the width of surface settlement troughs and horizontal ground displacements; and the results are more accordant with the field observations when compared with results of Loganathan’s formula.

Taking some tunnel as the background. and by using FEM numerical simulation , the factors affecting the safe thickness of roof of karst cave are analysed; and forecasting model of safe thickness of roof is obtained by support vector machines (SVM) and stepwise regression analysis.The result of calculation indicates that, SVM forecasting model not only has the advantages of convenience and swiftness compared with the linear regression model, but also has higher precision of prediction.

The compressional elastic wave velocities are measured for 25 granite samples in Henan Province before and after high temperature; and the complete stress and strain experiment of uniaxial compression is carried out. Through the experiment, the rock damage change due to temperature, temperature affects on rock porosity density and damage strain energy release rate, were observed. The experimental data show that the plastic strain of granite mainly depends on the strain energy of distortion due to deviatoric stress, but not on the strain energy of volume change.

From overburden layers, semipervious layers above depression-cone level drainage consolidation, porous media (geo-formation) compression and water compression, the ground settlement mechanism is analysed during foundation pit dewatering. Compression layers thickness due to dewatering is chiefly overburden layers, semipervious layers thickness above depression-cone level. Collecting the related data of 10 foundation pits dewatering engineerings, the practical values and theoretical values are compared and a set of modified-coefficient of surrounding ground settlement due to foundation pit dewatering (aggregately 880 groups of data ) are got. Using BP neural network method to process those data, we can find a sort of net mapped connection between given inputs and outputs ( ).We can use net connection to input a sort of , and get isoline of modified-coefficient which is corresponding with different , S. Accordingly we can find modified-coefficient of arbitrary ，S, which has practical value to foundation pit dewatering engineering of similar layers to forecast practical settlement at different times and distances from foundation pit.

According to the soil tests requirement, the control software system is provided for the soil static and dynamic universal triaxial and torsion shear apparatus developed jointly by DUT and SEIKEN INC, Japan based on modern computer control technique. The software uses VC++6.0 as a platform, and automatic control, data acquisition, data treatment is realized for the apparatus by using multithreading of modern computer technique, precise time determine technique, drawing technique, in accordance with modern neuron adaptive PID controller. After the improvement of the control system, the apparatus can perform any static and dynamic combination test; and the complete process of the test can be supervised for twelve parameters including stress, strain and displacement. More control precision and convenience for usage is realized for the new control system.