The effect of anisotropy on the pore pressure development for clay is investigated. A rotational yield surface is presented by introducing the Sekiguchi-Ohta stress ratio and Xin’s failure equation into the Modified Cam Model; and an anisotropic elastoplastic model is built. Based on this model, a new anisotropic pore pressure equation is presented, which can account for the pore pressure development induced by the rotation of Lode angle and principal stress. The equation is used to study the pore pressure development induced by the rotation of the Lode angle and stress axis direction under triaxial stress state. Finally, the pore pressure development in the plane strain anisotropic clay foundation under an strip load is analyzed by the equation. Results show that the pore pressure induced by the Lode angle rotation is small in the foundation. However, in the soil under the edge of load, pore pressure induced by the rotation of stress axis direction is significant, especially at a lower depth.

A soil nail FEM system, SnEpFem, developed by the authors, has the new features as follows: the interfacial soil-nail element adopts the better Desai element than the Goodman element; the mechanical behavior of the surface-layer element is described with an elastic foundation beam model; a pursuing failure mode is considered for the soil element. The SnEpFem system is used to analyze the influences of prestressed positions and magnitudes on the horizontal deflections, ground surface movements and scopes, uplifts at the pit bottom, and tension and plastic zones. It is found analytically that, (1) greater prestressed values applied at the upper-part and middle-part positions of slope is better for controlling the horizontal deflections, tension zone and plastic zone; (2) prestressed positions and magnitudes have a tiny influence on the ground surface movements and scopes, and the maximum uplift values and their locations; and (3) prestressed positions and magnitudes play a great impact on the stress distribution states and tension zones and plastic zones in the slope body. In terms of the above-mentioned analysis, the reinforcement mechanisms of soil nail are summarized. A case study is presented to illustrate the capability and merit of the SnEpFem system.

The behavior of undisturbed loess in the case of moistening or demoistening is investigated with single-line and double-line uniaxial compression test. According to the experimental results, the characteristics of collapsible deformation of loess changing with saturation level and pressure are presented. The collapsible deformation properties of loess during moistening or demoistening process and the influence of different stress-paths on collapse deformation characters of loess are analyzed. It is indicated that collapsibility coefficient curves can display different characteristics for different test method. The collapsibility of single-line method is larger than that of double-line method for lower initial moisture content, and is smaller than that of double-line method for higher initial moisture content. For certain value of initial moisture content in between, collapsibility coefficient curves of the two methods will intersect. This intersection phenomenon is caused by special structure of loess. Finally, the relation between collapsibility coefficient and initial moisture content is discussed.

The dense no viscous earth takes on the dilatancy and strain softening in course of the triaxial test. The model used in engineering extensively , such as the nonlinear elastic Duncan-Chang model and the general nonlinear elastic K-G model, do not contain the characters. According to a great deal of data by the triaxial test and research of Zipingpu Reservoir Concrete Faced Rockfill Dam’s material, the dilatancy and strain softening of the dense no viscous earth are analysed. The K-G model that contains the dilatancy and strain softening of the earth and the method to obtain the model’s parameters are introduced. The comparison between the theoretical and the experimental volumetric strain-shear strain curves verifies the rationality of the model .The model adapts to various stress path and obtains the parameters expediently, and can be used in FEM stress-strain analysis.

The mechanical behavior and mechanism of the interface between structure and coarse grained soil with slurry were investigated through conducting monotonic and cyclic tests of both interfaces with and without slurry. The interface with slurry between structure and coarse grained soil can be thought as the one between structure and slurry if the slurry is thick enough. Whereas, the behavior of the interface with slurry would be similar to that of the interface between structure and coarse grained soil if the slurry is not thick enough, which is only affected quantitatively by the slurry. For example, the shear strength would be reduced and the compression would be increased if the slurry becomes thicker. The behavior and thickness of slurry as well as the behavior of structure material and soil are main factors to the behavior of the interface between structure and coarse grained soil with slurry.

In the testing of impact-echo method in pile or other structure, the signals are got by velocity or acceleration transducers .The signals include the velocity response of the observing point and the influence of transducer behavior . First of all , the velocity response of pile are simulated by the numerical simulation software FLAC-3D .Secondly, the velocity response comprising the transducer behavior are gained by signal synthesis. And a new time-frequency domain analysis method, wavelet analysis, is introduced to study the influence of transducer on the velocity response. Finally ,a new suppressing method, wavelet suppressing method, for suppressing the influence of transducer is put forward. In order to validate the new suppressing method , several examples are given; and the results indicate that the new suppressing method is practicable.

A patent device , which is combined with the MTS815.02 Rock Mechanics Test System, is used to measure the seepage properties of non-Darcy flow in broken sandstone; and the permeability and the non-Darcy flow β-factor are obtained by steady-state seepage method. The relations between both the permeability and the non-Darcy flow β-factor and porous ratio are obtained through linear regressions. It is held that the seepage properties are mainly decided by the porous ratio; and the porous ratio is concerned with not only the current stress, but mainly also the history of loading. The test results show that the seepage flow of water in broken sandstone does not obey the Darcy’s law any longer, but obey the Forchheimer’s formula; and the characteristic of non-Darcy flow is more remarkable when the rock is under less porous ratio. Both the permeability and the non-Darcy flow β-factor can be fit by power functions of porous ratio.

The calcareous soil is a special rock and soil medium which composes more than 50 % Ca CO3. It has irregular grain shape, which correlates mechanical and engineering properties of compression and filling in calcareous soil. Using optical microscope, the grain projection of calcareous soil is got. With image processing tool of matlab,grain shape of calcareous soil is analysed in two ways:one is the traditional statistics way; the other is the fractal geometry. The results show that the grain shape of calcareous soil can be expressed by fractal dimension. And the character is getting more obvious when the grain is getting smaller. And the character of calcareous soil is analysed with its special cause of formation.

In order to increase the successful rate of the original complex optimization algorithm, the mutation particle swarm optimization (MPSO) calculation would be introduced for all design points of the initial complex and the current complex while the mapping of the bad design point was unsuccessful firstly. One of the design points is replaced by a point with quasi-optimum object function value that has been gotten by the MPSO based on the substitution rule of maximum complex central distance; and a new complex has been formed. The original complex optimization calculation would be continued with the new complex until the stopping criterion. The improved complex method is applied to searching minimum safety factors in two complex soil slopes; and the result has shown that the method is much more likely to locate the true minimum.

Load transfer tests of single pile and single pile with cap are conducted. The main characteristics of load transfer are as follows：the load on pile top is decreased while the total load increased. The cap on pile top makes distribution of axial force gently, frictional resistance decreased, and transfer function softened at upper pile shaft; meanwhile, frictional resistance at the rest increased; rigidity of pile top is changed a little.

Based on the Reissner-Mindlin plate theory, with the study on the deformation character of longitudinal joint and ring joint of shield tunnel, the interaction between the segment lining and soil layers, a flat shell-elastic hinge-foundation model is proposed. Furthermore, the relevant software is developed. The flat shell element is formed by assembly of Reissner-Mindlin plate element which is taken for the bending part and shearing part, and membrane element, where the bending and membrane effects are uncoupled. The elastic hinge element is employed to simulate the impairment of moment around ring joint and the difference of stiffness around longitudinal joint under positive moment and negative moment. The proposed model demonstrates much advantage in 3D analyzing of shield tunnel, such as inner forces of structure rather than stress. Finally, the presented example shows the validity and effectivity of the model in analyzing of interval shield tunnel, the feasibility of the model and program to other underground structures.

Landslide hazard is a complex system of holism, dynamic, open and random characteristics; and the artificial neural network model is a nonlinear dynamic system, which is fit for regional landslide hazard risk prediction. The BP model for the zonation prediction of the landslide hazard risk is established. Applying BP model and GIS technology, the landslide hazard comprehensive prediction of New Badong County is carried out. Based on hazard evaluating and vulnerability estimating, the landslide risk after the completion of Three Gorges Reservoir is predicted in study area. The applicability of BP model for landslide hazard risk prediction is proved. At the same time, the existing questions and the possible solving ways are put forward.

Slope stability calculations are usually done in the framework of limit equilibrium analysis. Safety factors are calculated for every slip surface; and the lowest value of safety factor characterizes the safety of the entire slope. During the calculating process of slope stability safety factors are treated as function of the coordinates of the potential slip surface center and radius of the potential slip surface. By applying tabu search for continuous variables the safety factors of slope stability are calculated. The safety factor calculated by tabu search is globally optimal. Thus the reliability of slope stability calculation is improved.

Characteristics of the vibration and impact water pressure are analysed based on the in-situ monitoring for the Qinzhou Harbour (second phrase) underwater explosive ramming. It is revealed that monitoring results of the vibration velocity agree well with the empirical formula; while the monitoring value of the impact water pressure is far less than that of empirical formula as the existence of tensile wave. It is also reported that there is pulse phenomenon for the velocity and the impact water pressure, and the intensity intend to decrease. In addition, it is also suggested that the value of the impact water pressure increases with the increasing throw-in water depth because of the tensile wave. The results can be a good reference for the similar engineerings.

General slope mass rating(GSMR) method is proposed. The continuous modification of discrete value which is composed of intact rock strength and rock quality designation and joint spacing, the modification of the relation between joint and slope, the excavation method, the inclination between joint plane and applied force, the state of artificial slope, the seism stress, the slope height and the revised coefficient F3 of Romana are considered. Because of this considering, rock mass mechanical parameters are determined by using the GSMR method, which is a workable method in engineering. That the discrete value can be replaced by the continuous modification to calculate the GSMR value is proved; and the rock mass mechanical parameters which are needed by the analysis for the slope stability are determined by using the GSMR method.

When the Three Geoges Reservoir impounding water and water level fluctuating, the hydrological condition of landslides will be greatly changed. Both the sudden drawdown of reservoir water level and rainstorm infiltration become major factors that effect on the stability of landslide. The stability evaluation of landslide is difficult in the sudden drawdown of reservoir water level. On the basis of the project that reservoir water level is controlled and the mechanical mode that the ground water acts on landslides in Three-Gorges Reservoir area, transient seepage due to the sudden drawdown of reservoir water level from 175 m to145 m is computed using the finite element. Disequilibrium push method is applied to stability evaluation of landslide under seepage forces. The results of the stability analysis show that permeability coefficient of landslides and the descending velocity of reservoir water level are main factors that effect on the stability of landslide When the permeability coefficient of landslides is less than 0.864 m/d and velocity is 2 m/d, the sudden drawdown of reservoir water level will take place. And water level on which safety factor of Landslide is minimum drops by 10m to 20m under 175m water level, which will provide scientific bases for the treatment of landslide in 175m water level in Three Gorges Reservoir.

With bilinear load transfer function，a set of equations for the axial load-settlement curve is established; furthermore, it is applied to the load-settlement of pile. Then hyperbolic load-settlement curve is applied to soil; an analytical formula for analyzing pile-soil stress ratio under the interaction of pile and soil is deduced; and the influence of several relevant parameters on pile-soil stress ratio are discussed. The study shows that the pile-soil stress ratio of soil-cement pile composite foundation is not only related with the characteristic of surrounding soil of the pile, but also dimension, elastic modulus of the pile and the total load of composite foundation. It provides a new way for the calculation of pile-soil stress ratio of composite foundation.

Structural elements such as beam, plate and shell, are widely used in the finite element analysis. However, the geometric characteristics of structural elements may lead calculation errors in some cases. For example, when analyzing composite structures with structural elements, some problems such as stress concentration and improper simplification of the geometric position will induce rather large calculation errors. Taking the slab and girder composite structure in subway station as the analyzing object, the corresponding coun-termeasures are put forward for the purpose of engineering practicality. By using these measures, reasonable result can be obtained with general-purpose FEM software.

Through a thorough study on the settlement development regularity of soft clay embankment and its settlement curve characteristics, based on every single S-type forecasting model and 5 types of S-type curves, and with the idea of combination prediction, a forecasting method and theory for settlement development of soft clay embankments are discussed emphatically; and a variable-weight combination of S-type curves is put forward for forecasting soft clay embankment settlement. Applying the mathematical programming method, the settlement development course of soft clay embankment can be forecasted by limited observed settlement data. The analytical result of engineering practice indicates that the forecasting curve obtained by this model and method can fit well the measured curve, which can meet engineering demand; what’s more, the variable-weight combination forecasting model is obviously superior to other single model so as to provide an effective and practical method for forecasting settlement development of soft clay embankments.

Dynamic construction process which consists of excavation, primary lining and secondary lining of deep buried tunnel (depth above the crown of tunnel about 490 m) was analysed in coal measures strata by 3D FEM numerical simulation. Characteristics of the tunnel support structural displacement and stress changes were analysed emphatically when underlying coal bed (dip angle =30°, thickness h=2.8 m) was exploited according to sub-level and full collapse method. Economic and safe prohibiting exploited depth of underlying coal bed is presented. So that a scientific basis for tunnel construction of coal measures strata and reasonable exploiting mineral resources in complex geological conditions is offered.

The regular hybrid boundary node method is improved and a new numerical method in geotechnical engineering is proposed in this paper. The source points of the fundamental solution are located on the boundary directly. There is no free parameter in the method which combines the modified variational function with the moving least squares approximation. It not only has the well-known dimension-reduction advantage of the boundary element method, but also is a true meshless method. Only randomly distributed nodal points on the bounding surface of the domain are required and the post-processing is very simple. At the same time, it is suitable for treatment of the semi-infinite space problems in geotechnical engineering. The numerical examples show that this method has high precision and is more suitable for computation in geotechnical engineering.

The negative friction problem of single pile, which is in layered porous half-space under the surface load, is studied by using Biot’s consolidation theory and integral equation method. The poroelastic half-space considered rheology is governed by Biot’s consolidation theory and the Merchant model is used to describe the porous half-space’s rheology. The second kind of Fredholm integral equations of the pile subjected to circular load in layered porous half-space is obtained by using the fundamental solution. The integral equations can be simplified by means of Laplace transform methods .These equations can be transferred to each layer by the transfer matrix and stiffness-matrix approach. By the numerical solutions of the integral equations and the corresponding inverse integral transforms the displacement, axial force, pore pressure and shear stress of the pile and pore pressure along the pile axis are obtained. It is indicated that the shear stress of the pile and pore pressure along the pile axis are obviously layer built.

In studying the contents of Hoek-Brown strength criterion, it is easy to discover that the complicated failure of engineering rock under loads is generalized to tensile and shear failures, and that factors affecting the rock strength are interpreted with two empirical parameters in the criterion, m ( the degree of stiffness of rock) and s ( the degree of failure of rock). So there is much practical value in engineering to study the two parameters m and s that influence the strength of rock. To satisfy the digital accuracy of engineering, the article mainly describes the regulation of the parameters, influencing the accuracy of strength value of rock masses; meanwhile it points out that there is important meaning and value to raise the accuracy of the two empirical parameters. Also this paper is beneficial to applying the standard to engineerings.

The large-scale triaxial consolidation drained shear tests have been carried out for geobelt reinforced crushed gravel soil and non-reinforced crushed gravel soil. The effects of reinforcement on stress-strain and shear strength of gravel soil are studied. The experimental results show that the failure strength and strain of the reinforced soil are increased. It is seen that the curves of strength between reinforced and non-reinforced soil are almost completely parallel; and their friction angles are fairly same; cohesion of reinforced soil is higher than the non-reinforced soil by the strength envelopes of reinforced and non-reinforced soil. The properties of shear strength of geobelt reinforced crushed gravel soil are studied by analyzing the relationship of stress-strain of reinforced crushed gravel soil. A calculation formula of shear strength of geobelt reinforced crushed gravel soil is drawn. This paper provides an experiment basis for studying mechanism of geobelt reinforced crushed gravel soil further.

When doing permeability test by using pressure pulse test method, the straddle packer system is adopted to isolate the test interval with the other parts of borehole; and then increase the pressure of test interval by high-pressure pump rapidly. The system is then shut-in and the pressure decay curve is recorded. By fitting the recorded data with the type curve, the permeability of test rock mass could be determined. Permeability test results of three intervals of one borehole in use of pressure pulse test method at granite mass in Gansu Province are presented. The test results are compared with Lugeon test results in the same borehole and statistical analysis of permeability test results in other areas. As one method of rock mass permeability test, pressure pulse test has superiority to other methods for its convenience and shorter time consuming, and is suitable for low permeability rock mass test especially.

Based on engineering geological features of tunnel setting, a1:1 hypostatic model of Tong-Yu deep buried highway tunnel is built. Combined measuring results, characteristics of yield degree, displacement, stress of surrounding rock-supports structure, as well as steel support force and lining axis force and bending moment of supports structure are analysed when the tunnel adopting full face method and bench method dynamic excavation. The analytical results show that the bench method there isn’t obvious advantage than full face method. The study provides a scientific basis for optimizing design and construction of deep buried highway tunnels.

The forming process of the layered crack and failure structure and effect of the disturbing stress wave intensity pmax on the forming of the layered crack and failure structure is simulated in software LS-DYNA. The characters of the shape and thickness of the layered crack structure of the surrounding rock in the roadway-rib are acquired. It shows the stress wave disturbance is an important factor to form layered crack and failure structure and induce the rockburst; and intensity of the stress wave decides whether the layered crack and failure structure is formed and how for the structure grows. It has an important significance of researching the mechanism of inducing rockburst and taking effective measures to control rockburst.

During the filling construction of the soft soil roadbed, the total settlement value could be predicted by using polynomial and time-series combined model. On the basis of measured settlement data, the polynomial prediction model could be discriminated and established by statistics; and the settlement trend value at a certain future time would be predicted. The random settlement could be gotten by random prediction model that is established by smooth and stable time series analysis method. The sum of above two prediction values is the settlement prediction value of the roadbed at some certain time. With the addition of new settlement data, the model parameters are continuously modified. The practical settlement prediction of the soft soil roadbed shows that the combined model is superior to the single polynomial model; and the absolute error value between measure and one-step prediction value is mostly below 5 cm. The more prediction step is, the greater error is.

Based on a program for geotechnical engineering, the functions of modeling reinforcing bar and cracking of concrete are supplemented; and a corresponding nonlinear FEM program is developed. The combination of cracking and plasticity in iterative calculation has also been achieved. Then, in accordance with the practice of a diversion tunnel for a certain hydropower station, the whole procedure consisting of construction, operation and plugging has been analyzed. The process shows that the algorithm routine has good stabilization and convergence, and can meet the requirement of accuracy. The results show that the crack extent, the crack width and the reinforced bar stresses increase with the increment of the original gap width in the operation; and the plastic zone in rock increases with the rising of the outside water level. So some measures should be taken to keep the rock stable in plugging time.

The sedimentary clay in the alternate marine and terrigenous environment of the north side of the Yangtze River estuary is possessed of the interbedded structure by interlacing the clay and silt, as well as the granular composition of high silt content. And its physical property indexes are in-consistent with its mechanical property indexes. The principal component analysis of multi-statistic theory is applied to analyze the potential of engineering characteristics through the routine physical indexes. The results indicate that it is not scientific that sandy loam is subjected to clay category; and the methods is not all reasonable estimating physical consistency state of sandy loam with relative water content and inferring its engineering characteristic.

By using resonant column apparatus, the dynamic parameters of interbedded soil and other soils in two sites are tested; the curves of dynamic shear modulus ratio G/Gmax and damping ratio versus dynamic shear strain amplitude of the soils in two sites are given. Compared with the variation range of G/Gmax vs. and D vs. curves of other soils, it is obviously that the G/Gmax vs. and D vs. curves of mucky silty clay and fine sand interbedded strata are more close to those of soft clay. By calculating the seismic response of the two sites, the results show that the interbedded soil weakens the peak acceleration greatly and its maximal shear strain amplitude is very big which is near to be failure under horizontal earthquake. The dynamic characteristic of interbedded soil is similar to that of soft soil; and this property is caused by its special conformation, i.e. the feeble horizontal joint planes are overgrown.

Considering the time distance effect of blasting vibration and the quasi-static method, and making use of the improved slice method, this paper puts forward an analytic method of slope stability under blasting vibration; and gets a new computing technology of dynamic stability of slopes under blasting vibration. The calculation of an actual engineering example shows that the method is more reasonable and closer to the actuality than the conventional methods.

Geomembrane strain gauge is a new kind of instrument used to measure strain of geomembrane. The key techniques in measuring large strain for the materials with low elastic modulus such as geotextiles and geomembranes were solved in the Chinese National 7th and 8th Five-Year Key Science and Technology Research Project. These techniques involved developing special method to achieve best sticking effect, seeking appropriate glue with the same lower modulus after being solidified to be compatible with geomembrane; developing new method in calibrating the gauge to get the two key parameters ( sensitivity coefficient k, and property index of geomebrane A) and solving problems in installation and protection. The gauge is reliable and durable in rigorous environment. It was used in-situ with good performance to monitor the strain of geomembrane in the 2nd-stage upstream cofferdam for Three Georges Project in May 1998.

The inherent uncertainty on geotechnical engineering is rootstock come into being risk. The kinds of uncertainty have been systematic analysis. The ways for analysis and reducing uncertainty have been summarized. To evaluate stochastic-field about geotechnical parameters has been reviewed. The uncertainty of the numerical model and variables description has been discussed. The risk analysis ways, status in quo, and its application for typical geotechnical have been integrated. The forward question for geotechnical risk theory, such as reasonable description of uncertain factors, imitation study of invalidation modes, risk analysis applied modern information technology, to quantify research the weakened risk by engineering, and anti-analysis of risk as well as relative question has been viewed. The application prospect of geotechnical risk analysis, with regard to imaging synthesized demand for engineering design, representing the unification between safety and economy has been stated. By way of supplement of decision-making or traditional design, quantified risk analysis can provide more assistant evaluation information to the decision-maker. However, it can only be described of “random certainty model” at present, therefore, the engineer none but make conservative selection in order to adapt and remedy incomplete acquaintance and limited information in geotechnical engineering.

The researches on seepage characteristic of fractured rock masses under the conditions of single fracture, hydraulic coupling, unsaturated seepage and considering the filled materials are reviewed and analyzed relatively. The results show that the experimental study played a very important role in researching on seepage characteristic of fractured rock masses; the more experiments that can simulate exactly the actual rock fracture should be done; the experiments considering the shear stress and 3-dimensional stress should be emphasized; the fully reasonable experiments of unsaturated flow in fractured rock masses are few now; the research on seepage characteristic of the filled fractured rock masses is more significant and should be strengthened. The available research directions are put forward for the future research on seepage characteristic of fractured rock masses.