Based on the thin layer stiffness matrix method, the behavior of Rayleigh waves in three typical media with smoothly varying stiffness is studied and compared with that in the layered media. The results show that whether the stiffness profiles are smoothly varying or layered, the fundamental mode dominates the surface wave field and the effective phase velocity approaches to the phase velocity of the mode in far field for the regular profiles. For the irregular profiles, the higher modes have a significant influence on the surface wave field. The intensity and the frequency range of the influence are related to variation of the profile stiffness. In media with smoothly varying stiffness, the tendency of the effective phase velocity of mode at high frequencies is above Rayleigh wave velocity of the medium with the smallest shear velocity; and the tendency of the phase velocity at high frequencies deviates from Rayleigh wave velocity of the surface medium. These characteristics are different between the layered media and the media with smoothly varying stiffness. The results show that when a medium with smoothly varying stiffnesses is modelled with a layered medium in the back-analysis of the measured dispersion data, the match between the measured and the theortical dispersion data and the calculated stiffness profile are influenced by number of layers.

The Mw7.8 Kunlun earthquake of 14 November, 2001, in the northern Tibetan Plateau of China, is the largest event in the Chinese continent in the latest 50 years. In this paper, layered viscoelastic models are calculated by PSGRN/PSCMP code; and the results are used to fit post-seismic deformation obtained from four GPS stations of CEA across the earthquake fault. The results show that model of a single anelastic layer of 10 km thick upper crust overlying an elastic lower crust cannot explain the amplitude of deformation; the relaxation model of 30 km elastic upper crust overriding 40 km ductile lower crust can explain the main features of exponential attenuation of post-seismic deformation. Combination of the two models, however, can fit the character better with deformation rate being higher in the first few weeks and slower rate thereafter. The viscous layer of lower crust provide the main control of the post-seismic deformation of long term decay of deformation in months, while the upper anelastic layer may contribute to the high rate of initial few weeks after the main earthquake. The result also suggests that rheological differences exist at two sides of the Kunlun Mountains fault.

Acoustic emission (AE) experiments of rock failure are carried out under uniaxial compression loading with AE location technique. Relationships between different stress levels with spatial distribution fractal dimension and b-value of AE events are studied. The results show that fractal dimension D and b-value of AE events can directly reflect the evolutionary process of microcracks initiation and propagation. In the initial stage of loading, on account of high proportion of small scale microcracks, the value of fractal dimension and b-value are higher and appear fluctuating, and in some rock samples they are increasing. With the increase of load, the distribution of microcrack turns from random to order, large scale microcrack are increasing, acoustic emission location events begin to cluster, fractal dimension and b-value begin to drop much quickly. The fractal dimension and b-value reach to the minimum value at the critical point of rock failure. During rock failure process, variable tendencies of fractal dimension and b-value are similar. Although it is difficult to confirm the minimum value of fractal dimension and b-value in practical application, continually declining of the two parameters can be seen as precursors of rock failure. Consequently, fractal dimension and b-value can be combined used to improve the accuracy of rock mass monitoring and forecasting in-situ.

The overburden thickness, stiffness and the layered sequence are important factors which affect the vibration characteristic of ground motion. The dynamic time-history analysis is one of the useful methods to deal with such problems. However, when the dynamic time-history analysis is used, it will take much time to finish complicated numerical models and calculations. Sometimes it is impossible that any anticipated results can be obtained because of numerical algorithm instability. A fast time-history algorithm is put forward to calculate the layered site response effect according to the principle of seismic wave propagation of the layered elastic medium. As a series analytical approach algorithm, not a numerical method, the algorithm need not solve equations based on discrete network models, thus it can improve the calculative efficiency enormously. Finally, the feasibility and the usability of the algorithm are also proved by some test models.

A series of fall cone tests are performed to determine the liquid limits and the plastic limits of fine grained soil. The result shows that the log-log relationships between penetration depth of fall cone and water content of some fine grained soil are clearly nonlinear; and the liquid limits and the plastic limits can not be obtained according to the linear relation. Effective test data can not be measured within the three ranges of water contents proposed by the present standards. The dependability is necessary to discuss about the liquid-plastic limit test results obtained from three ranges. It is possible that the contradictory and wrong classification results exist by using the liquid limits and the plastic limits obtained from the test data with straight line. The further test results show that the fall cone test is suitable for the silts over 13 % clay particles content since the shear strength is mainly controlled by cohesion; and the plasticity is available from the plasticity indexes. On the contrary, the fall cone test is not suitable for the other silts and the silty sands which are similar to silts, because the shear strength is mainly controlled by particle friction. At last, some opinions about the fine grained soil classification are given.

The two-dimensional consolidation problem of unsaturated soils is studied. If water and air in the pores can be regarded as a mixed fluid in unsaturated soils with , the deformations of unsaturated soils become the consolidation process of two-phase with soil skeleton and mixed fluid. Regarding the compressibility of the mixed fluid in pores, mixed fluid continuity equations are established. Then the stress-strain and mixed fluid pressure can be computed by mixed fluid continuity equations and balanced equations. If the suction and pore-air pressure are required, the water continuity equation should be established first to compute the pore-water pressure. A numerical example shows that the pore-air pressure is a minor factor in the consolidation process of unsaturated soils because the changing of the mixed fluid pressure is consistent with that of pore-water pressure; the deformation process is similar to that of embankment construction. Therefore, the approach is reasonable and very important to pragmatize computation of consolidation deformation.

Big size of particle such as crystal, mineral or aggregate is often seen in rock or concrete material. The mechanical behavior of these particles with big size crystal is simulated by clump, which can break during the loading process. According to the designed numerical uniaxial compression test of particle material with same number of particle, same spatial location and different radii of clump, the material’s mechanical response affected by these different sizes of crystals, minerals or aggregates is observed by means of rupture shape, fracture propagation, curve of stress and strain and energy dissipation process during the breakage of particle material under virtual experimental condition. It is found that big size particle does favor to material feature’s enhancement, can stop the expansion of crack and makes cracks produced around the clump, and that the enhancing degree is proportional to the clump radius.

The bearing capacity of rock sample is determined by material strength and confining pressure together. Both axial compression and unloading confining pressure can induce the failure of rock sample, but because of different stress paths, the failure processes under two conditions are different. The tests of conventional triaxial, pre-peak unloading confining pressure and post-peak unloading confining pressure are done to the Baishan marble which comes from access tunnel in Jinping Hydropower Station lying on Yalong River. The test curve and the rock sample failure characteristics indicate that rock samples are all showing brittle failure in pre-peak and post-peak unloading confining pressure tests; and the brittle characteristics in pre-peak test is more stronger than that in post-peak test. The deformations of rock sample in loading and unloading are increasing with the increase of principal stress difference; but dilatancy in unloading is bigger than that in loading under the same principal stress difference. Rock sample fails as confining pressure unloaded to about 60 % of initial confining pressure in pre-peak unloading confining pressure test; and as confining pressure unloaded to about 80 % of initial confining pressure in post-peak unloading confining pressure test, it fails. The conclusion can be for reference in internal correlative engineering stability analysis, design and construction.

The short-time rheology tests of No.3 coal seam of a Shandong colliery was carried out with MTS815 servo-controlled rock mechanical test system; the creep model and failure characteristics were analyzed. The experimental results indicate that the coal’ creep threshold coefficient is 0.915 and its rheological coefficient is 0.383; rheological failure of coal presents spatial inhomogeneity, plastic destroying is mostly as a whole but dominant failure plane orientation is sheared failure; mirco-ruptures occur in the rheological process of coal which is damage; and furthermore those damages occur on lower stress levels, just the accumulation and transfixion of lots of micro-ruptures induce the failure of coal sample; both damage and hardening exist in coal creep, the creep process lies on those two mechanisms; three polynomial experiential model can describe creep characteristics of this coal compatibly; and Nishihara model can describe its initial creep stage and steady creep stage, but not accelerating creep stage.

With the development of present underground constructions such as hydropower projects, traffic engineerings, mining works, energy sources and nuclear waste treatments, the tunnels’ surrounding rocks original carrying capacites and their actual permeabilities, etc. under project working states are the indispensable initial values of geological research; and these are also the reference for scientifically optimizing the engineering design. Because conventional measurement techniques and methods such as water pressure test do not adapt to the design requirement of rock masses permeability for complex engineering, it is necessary to carry out innovative and multiform fissure permeability tests. For a specific engineering, only using exact test method, the proper permeability can be mastered; and the accuracy and effectiveness of the engineering design can be ensured.

Shear strength is a basic issue for unsaturated soil; and how to quickly and economically determine the unsaturated soil shear strength index is an important issue for the implementation of unsaturated soil mechanics into engineering. The cohesion and the internal friction angle are functions of water content index; cohesion-degree of saturation curve (CDSC) and internal friction angle-degree of saturation curve (IFADSC) are gotten by simulating shear experiment through different paths, through which shear strength parameters can be obtained; CDSC and IFADSC are approximating straight lines in the same path when the change of saturation degree is small. A simplified method which provides advantages for applying soil mechanics theory of unsaturated soil to practical engineering is suggested to get the parameters through simulating different paths of shear strength experiments.

Based on comparative field tests of 15 super-long piles in 5 sites and comparative elastoplastic FEM numerical simulation of 2 super-long piles, the effect of the improvement of rock or soil strength at pile tip on total super-long pile lateral friction is studied. It is found that the total lateral friction of super-long pile increases 29.86 % ?112.17 % after reducing the thickness of residue at pile tip, or there is no residue at pile tip; the total lateral friction of super-long pile increases 33.07 % ? 66.95 % after grouting at pile tip; the total lateral friction of super-long pile increases 23.34 % ?235.65 % after penetrating pile tip into harder soil or rock stratum. It is concluded that, like general piles (short piles and middle-long piles), the improvement of rock or soil strength at pile tip can strengthen the total lateral friction of super-long pile.

The apparatus for static and dynamic universal triaxial and torsional shear soil testing was employed to perform stress-controlled coupled vertical and torsional coupling shear tests and monotonic torsional tests under undrained condition. Through a series of tests on saturated clay, monotonic torsional and rotation of principal stress under coupling cyclic shear behavior was examined. The strength of normal consolidated saturated clay in the monotonic torsional tests could be used to evaluate the overconsolidated monotonic torsional strength. The results of coupling tests show that the dynamic stress ratio and critical cyclic stress ratio linearly increased at uniform failure number with the overconsolidation ratio increased. This paper indicates that the effect of development mode of pore water pressure of coupling cyclic shear tests under different overconsolidation ratios is notable. The method of acquiring pore water pressure after ceasing coupling cyclic loading is able to better reflect the variation of water pore pressure with different overconsolidation ratios. It has been observed that a general strain fail criterion for clay is recommended for considering the integrative effects of torsional shear strain and normal deviatoric strain as well as cyclic strain and accumulative strain. Moreover, the general strain fail criterion is fit for the failure criterion of coupling cyclic test.

Working mechanism of gravl pile composite foundation under embankment loads is deeply analyzed. The system of embankment-pile-soil is simplified properly; the calculation model of pile-soil stress ratio is established; and the solving process of key parameters is given. The principle of minimum potential energy is adopted to deduce the formula of pile-soil stress ratio under embankment loads. Compared to the results which is observed in large-scale laboratory model test, the method put forward can satisfy the engineering requirement. Factors influencing the stress ratio are studied. The results show that the stress ratio is significantly affected by pile-soil modulus ratio and displacement ratio, while embankment height and embankment material less effect on it. The pile-soil stress ratio increases when the embankment height increases, it becomes stable when height comes to a fixed value; and it increases slightly when shear modulus of embankment fill increases.

The dissipation of excess pore water pressure of pile side soil caused by construction and the consolidation of subsoil caused by vertical load are major factors leading to the settlement of soil compaction pile in saturated soft clay. Changing rules of reconsolidation settlement of pile side soil are studied based on three-dimensional consolidation theory. The calculating formula of settlement of soil compaction pile is educed under reconsolidation settlement of pile side soil by using the interaction effect principle of pile and soil combining boundary condition. Terzaghi’s one-dimensional consolidation theory and layer-wise summation method are adopted to compute settlement of subsoil under vertical load. The calculating method is brought forward on settlement time-dependency of soil compaction pile in saturated soft clay. Engineering case is calculated and analyzed; and the calculating results accord with actual settlement rules.

Based on the Biot’s theory, the dynamic responses for a multilayered poroelastic soil subjected to harmonic horizontal load is developed with the transmission and reflection matrices (TRM) method. Applying the Helmholtz vector decomposition and Hankel transformation, the general solutions for the displacements, the stresses and the pore pressure are derived from the governing equations of Biot's theory. Utilizing the transmission and reflection matrices (TRM) method, the transformed domain solutions for the multilayer saturated poroelastic soil subjected to harmonic horizontal load are established. Numerical results for the displacements, the pore pressures and the stresses are obtained by performing inverse Hankel transformation in the space domain. Some numerical examples and corresponding analysis are presented. The present methodology is validated by comparing solutions with some known results. According to the analysis, it is concluded that the occurrence of a softer middle layer subjected to a harmonic horizontal load in the layered half space enhances the horizontal displacement and pore pressure. Comparing with the homogeneous case, the response of the multi-layered half space tends to contain higher frequency components and exhibits larger magnitude.

Determination of ultimate uplift capacity for enlarged-base pile plays a dominant role in engineering design. Resorting to limit equilibrium method based on local cutting slippage surface, a new simple formula of uplift capacity of enlarged-base pile in soft clay is deduced. Calculated results by the proposed formula have a good accordance with field test data. Based on above analysis approach, range of enlarged base is gained combined with the in situ test and engineering example. Finally, the analysis approach is applied to long enlarged-base pile and some useful conclusions are drawn: Failure mechanism of enlarged-base pile embedded in soft clay can be interpreted rationally with local cutting slippage surface; Range of enlarged base is related to pile radii and embedded depth.

Much attention has been paid to the development of the analysis method for slope stability, which is an unsolved problem in the classical soil mechanics till now. Based on the previous analysis methods and slope failure mechanism, a convenient approach, slope centrifugal method, is presented to calculate the safety factor of slope stability in the current work. In detail, the horizontal acceleration is applied on a slope and the value of the acceleration increases until that the slope failure happens. The safety factor can be obtained considering both of the centrifugal and the gravity on the failure slope. The comparisons between the presented method and the previous methods, e.g. the traditional limit equilibrium method and the finite element intensity discount method, is given by an example; and the sensitivity analysis of various physical parameters is given to show the validity of the presented method for analysis of slope failure. Results also show that the safety factor obtained by the presented method depends on the elasticity of the material in slope, slightly.

An indoor model test result of distribution regulation of strata resistance beside piles in the system of anchor anti-slide pile is introduced. In three test groups, two groups load on back of slope, the third one directly loads on the pile by jack. There are earth-pressure boxes on each pile to test the strata resistance. The distributing graphs of loading on the piles in the system is obtained from the tests. From the graphs, it is concluded that the strata resistance is focused on back of the piles. That is different from the anti-slide pile, in which the force is focused in front of the pile. Three distribution patterns of strata resistance beside piles in the system of anchor anti-slide pile and approximate scope for partial passive resistance values in front of the piles embedded the slide surface are given.

In the study of double reinforced composite ground, the settlements of pile and soil of composite ground are different, which results in vertical relative displacement in fill column and change in stress state. The shear displacement method is adopted to analyze the strain and stress of horizontal reinforcement. Equations about pile-soil stress ratio and distance of pile sticking into embankment are deduced from analyzing the vertical mechanical equilibrium of soil unit, in consideration of the influence of soil mechanical properties (c, ) and horizontal reinforcement. Finally, when the equations are used to analyze the practical project, its feasibility is proved by the reasonable agreement between the calculated and the measured values; meanwhile, all kinds of factors that affected pile-soil stress ratio are analyzed systematically; and some rules are obtained.

A series of small-scale model tests were carried out to measure stresses developed in testing quartz sand bed during loading and the corresponding variation during unloading in glass cylinder and steel rectangular box. A new conceptual stress release model was proposed based on the model test results by considering the fundamental behavior of granular materials. It was found that stress in sand increased linearly with applied load. There is almost no change of stress at the beginning of unloading; significant stress release took place in later period of unloading and shown an obvious boundary. It is analyzed that the difference between loading and unloading was attributed to the internal friction of sand. Stress can only release when “removed load” is larger than internal friction resistance. Whether or not and how much stress will release not only depends on the internal friction resistance, but also is related with magnitude of unloading and stress state prior to unloading.

Global warming has aroused a close attention all over the world. Emission of CO2, as a major greenhouse gas, must be reduced for the purpose of stabilizing the concentration of CO2 at a safe level. CO2 capture and storage (CCS), a new kind of geotechnical engineering, is a potential cost-effective and fossil energy-compatible technology, which is considered to play a significant role in global emission control and be helpful in reducing the total greenhouse gas control cost and mitigating the economic impact caused by the drastic transformation of energy structure. Industrialized countries have drawn up CCS R&D roadmap. CCS research is just getting started in China and the R&D roadmap has not been drawn up. A mid-long term R&D technical roadmap of CCS in China is presented based on authors’ investigations and analyses.

Based on one-dimensional consolidation-creep laboratory test, the creep deformation of muddy soft clay in Tianjin littoral area is performed. A nonlinear rheological model is established; and the model coefficients are determined considering the characteristics of littoral soft clay. Furthermore, a settlement equation is deduced from the rheological model and applied to the settlement calculation of the soft soil under Beitang reservoir’s dam in Tianjin littoral area. Numerical results agree well with those of field measurement, which provides convincing evidences for model’s excellent solution quality and fidelity, and shows the necessity of considering the soft clay’s nonlinear rheological characteristics in settlement analysis. Finally, a pre-estimation on long-term creep settlement of the soft clay in Tianjin Binhai New Aera is presented.

Based on fuzzy mathematics and extension theory of rock mass quality evaluation, the weight is the key to the identification. At present, despite there are many ways to determine the weights, it is not very convenient for the actual projects. By introducing the extension theory of hierarchy eigenvalue, the weight calculation will be solved by conversing it into the optimization problem; it is a new meaningful exploration. Combining chaos optimization algorithm and extension evaluation method, the sample data are back analyzed and the weight is obtained. Choosing influential index according to the actual situation, the evaluation criteria are established; sample data are extracted, and the data are analyzed by using CAExWeigh.exe. The calculation results are analyzed based on actual engineering geological conditions. It is shown that the method is reliable; meanwhile, the weight factor is the mean value of the impact on the statistical significance to some extent; it’s meaningful only when its index value is in a certain range.

The rigid body limit equilibrium method and the nonlinear finite element method are often used in the analysis of anti-sliding stability in deep foundation of gravity dam. But the rigid body limit equilibrium method can not reflect the process of progressive instability and mechanical mechanism on failure for rock mass while the nonlinear finite element method is difficult to solve the displacement discontinuity of weak structural plane. Combining the research with Xiangjiaba project, the analysis of anti-sliding stability in deep foundation for 4th monolith has been carried out using interface element method. The results can supply most dangerous location, the scope and distribution of failure zone in weak structural plane and process of progressive failure in dam foundation as well as the safety coefficient of possible sliding body. These achievements provide an important technical reference reliance for dam foundation treatment measures. The computational results show that the interface element method can naturally describe discontinuous deformation of rock mass such as dislocation, openness and sliding. Besides, this method is characterized by good adaptability, calculation conveniently and high compatibility, thus being regarded as an effective way to make an analysis of anti-sliding stability in deep foundation of gravity dam

The composite retaining structure of soil-cement pile and concrete pile (named MC pile) is applied to the projects in recent years. Due to lack of researches in view of service mechanisms and deformation characteristics of the composite retaining structure, experience design method that lacks of theoretical basis is usually applied to design composite retaining structure in practical project. Through studying some problems of composite retaining structure, especially several key issues about designing MC pile retaining structure, the methods to design M pile and C pile are put forward; with the characteristics of the MC pile composite retaining structure, a new stability calculation method for the composite structure design is proposed. Finally, applying the design method to actual project, the results demonstrate the feasibility of the method.

The engineering environment of subway foundation pit is complex with too many influencing factors; and the analysis of risk factors is incomprehensive due to the uncertainty of risk events in the construction of foundation pit. However, up to now, the conventional risk identification method can’t consider all the risk factors. A risk identification method based on the fault tree analysis (FTA) method is proposed to identify the risk factors with the combination of the work breakdown structure (WBS) and risk break- down structure (RBS). The risk factors or risk events are judged and explained by the coupled analysis of WBS and RBS; and then the fault tree of subway foundation pit risk is established. Furthermore, sensitivity analysis is carried out based on FTA; and then precaution measures of risk events in subway foundation pit are proposed.

Anti-seepage in thick overburden dam base is one of the key problems for dam construction and dam safty. It has been used in several dam projects that the plastic concrete anti-seepage wall plus grouting curtain regarded as the waterproof system. The anti-seepage wall construction impropriated the time limit for such projects; so, it should be shortened as its possible. To study the optimum depth of anti-seepage wall is needed. An analytical solution for grading downwards the anti-seepage wall is deduced based on the drag index methods. And it is studied in detail that the law of grading downwards the anti-seepage wall varied with its depth increase. The results show that the depth of anti-seepage wall in limited thick overburden is not the deeper the better. By contraries, it was sure that there was an optimal depth, in which grading downwards the anti-seepage wall is the least. The value of the optimal depth is related with the depth of the overburden. In general, when the relative depth ratio between the depth of anti-seepage wall and overburden is about 0.7; grading downwards the anti-seepage wall is at the least.

The large ancient underground rock caverns in Longyou is an important component of grotto cultural. Current task facing the long-term preservation of these unmovable cultural relics is arduous and challenging. The weathering velocity of these caverns is accelerating. The deformation failure of the caverns' surrounding rock is deteriorating. Construction of the maximum-security routes in the caverns might be an efficient way to ensure the security of tourists and reach the target of long-term preservation. In order to establish an optimum schemes, field investigations for the deformation and failure situations of caverns' surrounding rocks are carried out. According to field investigation results, several kinds of failure characteristics are recognized. Numerical analysis is also performed using FLAC3D code. The safety coefficient evaluation method is introduced to assess the stability state of caverns' surrounding rocks in the research progress. Also, various kinds of schemes for construction the maximum-security routes in the caverns are contrasted; and the maximum-security routes through No.1 to No.3 caverns are determined preliminarily.

The largest shallow coal field in the world is in west China. The coal seams have thin roof and thick sandy overburden. The failure of thick sandy soil layer spreads to the ground surface in shallow seam mining, which will cause heavy disasters, such as dynamic ground pressure in coal faces and ground surface subsidence. Through physical simulation model tests, the development of fractures in sandy soil layer and on the ground surface is observed to be temporary structure of “arch beam” and periodic “arch rock pillar”structure. The “arch beam” mathematical model is set up; and the stress distribution in the “arch beam” is presented. Furthermore, the criterion of thick sandy soil layer failure is set up; and the position of periodic tension fracture is determined. This work provides basis for analyzing roof pressure control and surface subsidence.

The safety risk evaluation of metro tunneling-induced effects on adjacent buildings and structures is one of the problems urgently to solve. Considering the interval distribution characteristic of ground parameters in engineering, the interval analysis theory is suggested to estimate the interval of the response of buildings and structures. Based the response interval, a risk index is defined by introducing the risk evaluation function; and the other risk index is defined by assuming the response is the uniform distribution. With the two risk indexes, the event that whether the buildings and structures adjacent tunneling are safe or not is classified into the impossible event, the risk event and the sure event. The risk event is further classified into 3 classes, and responding measures are recommended. In the end; the application of the defined risk indexes to engineering is explained in an example.

The unconfined compression test is utilized to research on the cemented marine soft clay and testifies that there is considerable discrepancy between the effect improved by slag cement and that by Portland cement. X-ray diffraction analysis is employed to investigate the mechanism and the causes of the discrepancy. It is observed that the strength of the cemented soil is related to the amount of the cement hydrates. Slag cement generates more hydrates, and restricts the influence of soluble salt in the soft clay on cemented soil.

Because of the wind erosion, the empty cavity phenomenon is formed, which shows different soils have different abilities of resisting wind erosion at the mesa of Jiaohe ancient city, Turpan. The ability of resisting wind erosion is the results of many factors in which the microstructure is the important inner factor. Wind erosion rate is an important physical quantity of showing soil’s abilities of resisting wind erosion. The experiment of wind tunnel and the microstructure analysis are applied to reveal better corresponding relationships between wind erosion rate and microstructure indexes, such as particle area ratio particle roundness, equal diameter of pore and filling ratio of pore. Furthermore, by adopting related analysis methods, better related relationships between wind erosion rate and the indexes of all characteristics are analyzed and approved. Through regression analysis method, the regression equations between the three kinds of wind erosion rates and odd index, even multi-index are built; and the microstructure characters which have notable influence on the ability of resisting wind erosion of soils are validated. Above results also provide micro basis for wind erosion evaluation of soils.

A large amount of analyses of model test and in-situ test results show that both light dynamic penetration and cone penetration tests can be used in testing the relative density of the back filling by coarse sand in highway roadbed construction; and there are good linear relationship between blow count N10 and static point resistance Qc. In order to disclose the root of the pertinence theoretically, Lade model is applied to three-dimensional finite analysis to simulate the two test processes; it is proved that the stresses, strains and displacements around the two kinds of test cones have great comparability.

Cone penetration tests (CPT) measurements are widely used in soil characterization. An important precondition for subsequent study is the stationarity of the soil random field, which can be tested by Bartlett statistics. But the rejection criteria is not accordant when using different autocorrelation models, which brings difficulty in practical using. The new model, LGS, can solve this problem because it can be adaptive with different autocorrelation functions. The simulation of the new autocorrelation model, LGS, is presented based on the random field theory. The stationarity of soil characteristics is tested using modified Bartlett statistics based on the autocorrelation model, LGS, which unifies the rejection criteria. Two examples are analyzed; the result calculated by the program shows that this new model is adaptive with different autocorrelation functions; and the problem of rejection criterion can be solved well.

Equivalent pollution control is proposed as a basic principle for the design of alternative bottom liner at municipal solid waste (MSW) landfill site. As a representative alternative liner, compacted loess is employed to illustrate the design method in case that the accumulative concentration of pollutants is selected as a primary parameter for the leachate pollution control.

Hyperbola method, three-point method, exponent curve method, Asaoka method etc. are widely applied to settlement prediction for soft soil ground; but less study of applying to case of small settlement. With regard to the four methods, the small settlement data from the construction site of a passenger dedicated railway line are used to study the influence of starting point of calculation time and span of starting and ending time of the sample on relative error and prediction effect of the last observed values are checked. Comprehensively considering correlative coefficient and relative error, the applicability of every method is studied and the advantages and disadvantages for every method are analyzed. The research results show that the exponent curve method can not fit to the case of small settlement: other three methods all provide better fit to the real data when the settlement data fluctuation is small; however only three-point method and Asaoka method fit better if settlement data fluctuation is not small.

Settlement observation is an important method for quality detection in explosive compaction embankment. Nowadays, the traditional observation method is more used; it requires longer time and consumes time and power. By analyzing the characteristics of grey Verhulst model, the embankment settlements of various periods can be predicted according to the observed numbers by applying the Verhulst model. The prediction has good compliance with the actual observation; moreover, the finals settlement and the time it required are predicted. The result shows that the grey Verhulst model is very effective and can be applied to the similar projects.

A series of laboratory tests are performed to investigate the change of water content for quick lime treated dredged clayey soils with different quick lime contents and original water contents of dredged clays. With introducing a new concept of decreasing ratio of water content, the change law of water content of treated soils is obtained. That is, the decreasing ratio of water content has the same linear relationship with quick lime content for different original water contents of dredged soils. In addition, a simple method for predicting the water content of treated soils is proposed; and its effectiveness is verified with the data published in literatures.

The development process of negative skin friction is divided into two stages. At the first stage, it is mainly controlled by the relative displacement between soil and pile, and at the second stage, it is mainly controlled by the increase of soil strength caused by consolidation. Based on the re-analysis of data from history cases in Japan, Canada and Thailand, the relation between drag load and time can be fitted with hyperbolic curve, in which the physical meanings of parameters are preliminarily discussed. The results of history cases indicate that the calculated results fit well with in-situ test data, which verifies the feasibility of the method presented.

Several optical measurement methods applied to measure displacement of model are discussed. For automated grid method, grid dots are arranged easily on model surface. After improving the program, dots can be encoded automatically in the condition of removing dots, and can be encoded handily by human-computer dialogue if necessary. For speckle correlation method, speckle is arranged easily on model surface. After improving the program, displacement can be acquired automatically in the condition of removing speckle. Displacement cannot be acquired if speckle is destroyed badly. Other optical methods are not suitable for experiment conditions.

Based on the self-balanced test of S10 pile in the Third Karnaphuli Bridge, the ultimate bearing capacity under extreme event and limit state is analyzed; and it is compared with the bearing capacity controlled by pile deformation. The results are similar between deformation control under structure stress analysis and ultimate bearing capacity under limit state, the limit top settlement for the ultimate bearing capacity should be determined according to the limit state of structure, which is helpful for playing the bearing capacity of super-long pile as long as structure internal force caused by settlement deference can be controlled in design range. The calculation method of determining the pile stiffness is introduced, which is more accurate and useful than traditional one.

In order to develop a rational numerical analysis and design method for predicting the bearing capacity and deformation of the pile foundation on Ryukyu calcareous sediments, a series of nonlinear elastoplastic finite element analyses are conducted to simulate pile vertical loading tests. In the finite element analyses, the calcareous soil is modeled as an elastic perfectly plastic material. The load and displacement relation of pile foundation is analyzed with different strength reduction factors for the interface between the pile and calcareous sediment. The analytical results indicate that the strength reduction factor significantly affects the load and displacement of pile foundation on Ryukyu calcareous sediments; and that the proposed FEM could reasonably simulated the experimental results when an appropriate strength reduction factor is used. In addition, the soil plugging effect for open-ended piles is also examined from the FEM results.

Based on the North Gongti Road Station of Beijing Metro line 10, the construction steps and mechanism of large section crossing tunnels constructed with the pile-beam-arch (PBA) tunneling method were described. The behaviors of preliminary lining of tunnels was analyzed using FEM. The results showed that the preliminary support system of tunnels worked interactively restricted within certain area and the tunnel crown settlement decreased from junction area to both sides. With the influence of latterly constructed arch, the tunnel crown of the main tunnel jointed with the vertical tunnel manifested tensile state. The folding beam settled in the tunnel junction could diffuse the pressure of upper arch and weaken the stress concentration. The results could be a reference to design and construction of crossing tunnels constructed with PBA tunneling method.

The explicit dynamic analysis of the reinforcement effects and dynamic characteristics of rock bolts is carried out by LS-DYNA software. The change features of vertical stress of rockmass, vault displacement and axial strain of rock bolts themselves caused by explosive waves are compared whether wall rock is reinforced or not. By comparing the cavern that is not reinforced, the stress of wall rock is larger and the displacement of vault is less than the cavern that is reinforced by rock bolts. By analyzing the axial strain temporal curves of rock bolts, the response to the dynamic loads is different when rock bolts’ installing angles are different. The rock bolts of vault bear pressure at first and tension after., and the rock bolts in upright wall bear tension absolutely. The axial tension strain generates at these two positions. The comparison between the axial strain temporal curves and the corresponding curves is carried out in model test. These two curves are compatibility. This simulation provides the references of arrangement methods in wall rock of tunnels reinforced by rock bolts under the effect of dynamic loads.

With the advantages of efficiency, advancement and non-destruction, ground penetrating radar (GPR) can scan the lining of tunnels successively and obtain objective and accurate images. Because of the transitory application of GPR in China and the complexity of radar images, there are still some problems in the identification of cavity radar images. Accordingly, through various tests the cavity feature is obtained; and GPR waves and images of tunnel lining cavity are simulated using 2D-FDTD. Finally, a forward numerical simulation program is developed with VC++, which simulates a few familiar cavity models in detection of tunnel lining. Comparing the simulated waves and images with the measured, and it is shown that the simulated, which has the cavity feature, is similar to the measured. The good results verify the feasibility of 2D-FDTD.

Effects of surrounding rock, clear-distance and buried depth on blasting vibration characteristics of small clear-distance tunnel are analyzed by two and three-dimensional numerical simulations; and effects of blasting in lately excavated tunnel on early excavated tunnel are studied for different support systems, reinforcement measures of middle wall of early excavated tunnel and different construction plans of lately excavated tunnel. According to research results, such blasting control measures of tunnel construction are provided that middle wall should be reinforced by grouting, and primary support of early excavated tunnel should be closed down in time; and hole cut should be far away from middle wall and advance should not greater than one-third of clear-distance. All measures can be for reference in design and construction for blasting excavation of small clear-distance tunnels.

In order to study the rock fragmentation mechanism and its influential factors, a numerical simulation method for simulating the rock fragmentation by the tunnel boring machine (TBM) cutters is proposed which is based on particle flow code (PFC) method. With PFC method, the two dimension numerical models of rock material and TBM cutters are created. The results show that the rock fragmentation process can be divided in 3 phases, which are fragmentation by impact and extrusion, appearance of micro cracks, extending of dominating tensile cracks. And this proves the extrusion-tension theory of rock fragmentation by TBM cutters. When the cutters have the same penetration depth, and the angle and width of cutter rings become larger, the crash zone and the number of dominating tensile cracks enlarge, which means the cutter’s fragmentation ability is enhanced. Compared with the plain cutter rings, the wedge effect of wedge cuter rings is more remarkable, which make the radial tensile cracks extend faster and deeper in rock material. The damage of medial strength rock by cutters is more remarkable than the high and low strength rock.

A finite element method in moving coordinate is formulated in order to analyze the vibrations of railway embankment and ground under moving loads. A viscoelastic boundary condition in moving coordinate is also formulated to simulate the waves transmitting at boundaries. In the formulation the ground is assumed to be a layered viscoelastic half-space medium; and the railway embankment is modeled as a viscoelastic beam. The transient state numerical results agree well with the field measurement data at Ledsgård, which shows that the proposed method is effective in solving moving loads problems.

Weibull distribution is adopted to simulate the heterogeneity of Young’s modulus and strength of coal; and the seepage-stress elastoplastic coupling mathematical model of heterogeneous coal is presented based on elastoplastic theory of coal rock and the gas flow theory. Then the finite element discretized equation of the model is obtained; and the code (coupling analysis) is developed. In a case study, the gas flow process for a gas production well in Liaoning is analyzed with the model; and some conclusions are obtained. During the gas production well works, the change of the effective stress of coal causes coal plastic failure. In plastic failure region the permeability increases by 4.9 times than initial one; while the permeability in elastic region reduces to 22% because of effective stress increasing. The gas pressure, effective stress and deformation of coal in the case study all are asymmetrical, yet obey theoretical laws. It is proved that the Weibull distribution can simulate the heterogeneity of coal.

Fracture water lying in fractured rock mass, has been considered as a positive factor for the damage of rock wall. Rock bolts, as an effective rockmass reinforcement measure in civil and mining engineering, enhance the stability and improve the damage of jointed wall rock through restraining the formation within the rock masses. According to the damage mechanics theorem, the flexibility tensor variation may externalize the macroscopic effect of rockmass damage. Associating with the flexibility tensor of the intact material, the accessional flexibility tensor is used to show the effect of the joint on the rockmass. The seepage pressure flexibility tensor is also introduced to denote the effect of seepage pressure on the rockmass intension. The accessional stiffness is introduced to represent the enforcing effect of bolt on the rockmass, the inversion of which is the flexibility tensor. So the paper has studied systematically the coupling mechanics between the seepage field and the damage field in the anchoring jointed rockmass under seepage pressure. Based on the Betti energy reciprocal theorem and self-consistent theorem, the constitutive model for the anchoring jointed rockmass under the seepage pressure is obtained under the conditions of compression-shearing and tension-shearing. The calculation method and finite element procedure come into being according to the above model, in which half solution coupling method is applied to coupling the damage and the deformation. The above program is applied to actual project to model the ground movements that occur when the subsea tunnel is installed in the jointed rockmass. The computation results validate their validity; and the analysis indicates that the damage effect of the seepage pressure on anchoring jointed rockmass can not be ignored.

As a novel version of penetrometer, T-bar is extensively utilized in in-situ measurement for undrained shear strength of marine soft foundation. However, the effects of penetration velocity, anisotropy of soil strength and gradual softening on penetration resistance of T-bar penetrometer are seldom systematically investigated. The simple elastic-perfectly plastic Tresca model is modified to allow for the above mentioned effects based on the finite element software ABAQUS. Then the numerical simulations for penetration resistance mechanism of T-bar penetrometer in soft clay are conducted. The results show that the effects of strain rate, anisotropy of soil strength and strain softening on T-bar factor are appreciably large. Compared with the upper bound limit analysis, the present finite element solution is validated.

The discontinuity network modelling is one of the most common used methods to get rock mass structure model. Mechanical and hydro-mechanical models can be set up based on discontinuity network models; and then fine numerical simulating work can be carried out, which is an attractive direction in rock mechanics. Because there have no well used software to translate network modelling result into mechanical or hydro-mechanical grid, a complete set of programs has been developed by the authors, which can be used to form connective hydraulic network and finite elements grid based on discontinuity network. Relevant algorithms and realizing processes are described in detail. It’s expected that the achievements would be helpful to other researchers.

Piles supporting bridge abutments on soft clay may be loaded laterally from horizontally soil movements induced by the approach embankment. 3D finite element modeling of piled bridge abutment is set up to explore the behavior of piles induced by embankment load which is compared well with the data from the site monitoring. The results indicate that the bending moment of piles and settlements of bearing platform calculated are consistent with the data from the site monitoring. The curves of the maximum bending moment plotted against the average stress applied by the embankment in the middle pile row and the rear pile row are double broken lines which are consistent with what Stewart, D.P. suggested. However, the average stress corresponding to the threshold (at the intersection of the two lines) do not occur at the same embankment load which are about 3.34 times weighted mean ccu of layered strata in the middle pile row and about 2.22 times weighted mean ccu in rear pile row. The curve of the maximum bending moment plotted against the average stress in front pile row is linear. The deflection of the pile cap plotted against the average stress applied by the embankment doesn’t agree with the curve Stewart, D.P. suggested. The curve obtained in the paper is nonlinear and can be divided into two portions. The maximum bending moment of the front pile row is developed at the upper portion of the clay layer rather than near the pile cap, but that of the rear pile row is developed at the upper portion of the clay layer under low embankment load and then shows the maximum value at the pile head under high embankment load.

The finite element method is used to investigate the consolidation behaviour of strip footings embedded in a finite stratum based on Biot’s consolidation theory. The calculation is carried out using a well-known finite element software, ABAQUS. The influences of three factors: (1) the ratio of buried depth to the thickness of the stratum, (2) the ratio of footing width to the thickness of the stratum, (3) the Poisson’s ratio of the soil skeleton on the average degree of consolidation settlement have been examined. Based on the results of analysis, a new normalized dimensionless time is suggested. Solution charts for determining the average degree of consolidation settlement of strip footings embedded in a finite stratum are presented. The charts can provide engineers with a quick answer to the design issues. The maximum error caused by using the solution charts is within 3 %.

In order to simulate and make optimum analysis of partial pressure joint arch tunnel, a 3D finite element model is established. The simulation results are compared with the measured data in site. Arch crown settlement, stress and displacement of middle wall, plastic area distribution of surrounding rock, and variation of initial and secondary linings are analyzed. Then, the joint arch tunnel’s optimal construction sequence, the optimal construction space of two holes, the suitable construction method of cutting face and cycle length are determined by the simulation. The results provide a scientific basis and technical guidance for the construction optimization of partial pressure joint arch tunnel.