Shear strength properties of clay are related to stress variation and consolidation state. By using the conventional triaxial shear test, the effect of stress paths on it can not be reflected actually. With the self-made triaxial equipment, a series of special shear tests has been carried out to study the effect of drained and unloading stress paths on shear strength properties of a typical soil in Tianjin city. It is shown that the total shear strength properties are different from that of conventional triaxial test. And the total shear strength properties under drained and unloading stress paths are different from the experimental results under undrained and unloading stress paths. And the effective shear strength properties under different stress paths are equal.

Based on the equations of coupled thermo-fluid-mechanics, a model of subgrade soil responding to the change of atmosphere is established with the boundaries of actual evaporation. The influence of climatic evaporation on a certain subgrade soil is analyzed by the model. It is shown that the behavior of subgrade soil can be perfectly modeled by the equation of coupled thermo-hydro-mechanics with the formulation considering actual evaporation. The water vapor diffusion is very important to evaporation and volumetric water content under the condition of evaporation. By studying the influence of the periodic change of weather on the subgrade soil by simulating the difference of evaporation with sine wave, it has an important influence on surface layer. There is a desorption-absorption cycle of moisture of surface layer with the periodic change of evaporation.

In order to research the mechanical characteristics of unsaturated intact Q2 loess, the mechanical parameters of unsaturated intact Q2 loess are derived entirely from results of isotropic compression and conventional triaxial compression tests. The yield function and the hardening rule with plastic work as hardening parameter are derived by test results and the theory of soil plastic mechanics. The Elastoplastic model of unsaturated intact Q2 loess is set up. The comparison between the measured and predicted stress-strain relations and volume change behavior for unsaturated intact Q2 loess shows that the model can predict soil behavior of shear compression and dilation with good accuracy.

Using a new type rock meso-mechanical testing system, an observation and experiment on whole process and real-time of gypsum breccia is carried out under the condition of uniaxial compression load. Digital images of germination, extension, juncture, perforation till macroscopical fracture of micro-crack which is the rock initial damage, are obtained under the condition of different water contents. On the basis of meso-damage mechanism and stress-strain curve, the process of damage and fracture is divided into four phases. Considered the condition of water damage, rule of rock damage evolvement is researched. A damage threshold value of stress is discussed. Finding out that initial damage microcrack, which is caused under the influence of water environment, is an important factor to generate softening of gypsum breccia.

The mechanism and features of creep of Shanghai sands are researched through oedometer tests. The effects of stress histories on creep deformation are also investigated. The experimental results show that the Shanghai sands exhibit nonlinear creep obviously; and the relationship of stress-strain-time can be expressed by power functions. The stress histories have significant effects on the creep of sands. When the load is less than the preloading, the creep of sands is unremarkable. The main reason for creep of Shanghai sands is that the sand grains slide along one another.

Based on triaxial compression and permeability test of brown mudstone and clayey siltstone perpendicular to and parallel with bedding planes, the change rule of elastic moduli of brown mudstone and clayey siltstone is obtained. And elastic modulus expression of soft rock is proposed with different confining pressures and angles of bedding plane. Coupling relation between permeability tensor and stresses is key problem in hydromechanical coupling analysis of anistropic rock. The stress-dependent permeability tensor of soft rock is introduced where principal stresses do not coincide with the principal permeabilities, so control equation of stress-permeability relationship is presented. Measured data and calculation results are compared. And these can be used in the research of the model of hydromechanical coupling in anisotropic soft rock.

Particle breakage of several kinds of rockfill materials is analyzed based on many groups of large-scale triaxial shear tests. The experimental results indicate that the quantity of particle breakage occurred during preparing specimens can not be ignored. So the gradation curves for preparing sample should decline certain percentages in order to retain the designed initial gradation before consolidation. Large grain fracture mainly focuses on the surface zone in the sight of the changes of gradation. And the amount of particle breakage, occurred in whole shear experiment process, increases linearly when the confining pressures raise. Moreover, the available data show that the quantity of particle breakage appears to increase with the addition of water.

The damage process is accompanied by the acoustic emission (AE) for brittle materials such as rocks. AE rule of fine sandstone was investigated under cyclic loading at different loading rates and different stress ranges. The research shows that changing upper limit stress has strong effect on AE rules, and changing lower limit stress advances the time of AE at the end of cyclic loading. Increasing loading rate makes the AE rate bigger, and accelerates the process of rock failure, especially, when the main crack is forming and expending. AE has the different changing mode at different stress ranges and different loading rates, which indicate the different deformations and failures rates of rock.

Current researches indicate that the stress path of rockfill dam during dam construction can be approximated as that the principal stress ratio keeps constant. According to the triaxial drained tests conducted in large scale triaxial apparatus under two types of stress path, which are isotropic consolidation tests and shearing tests of constant stress ratio, a four moduli incremental nonlinear model was proposed. The model can not only present functional expressions of bulk modulus K and shear modulus G of rockfill, but also calculate volumetric strain produced by shearing stress and shearing strain produced by mean principal stress with the coupling modulus J1 and J2. Compared with the test data, the model can present good predictions of the stress-strain relationships of rockfill under the path of constant stress ratio.

It is generally important to maintain the stability of soft clay foundation as road embankment is rapidly filled. Some controlling standards of displacement or movement velocity are currently employed in road embankment construction regulations. But some practical cases with foundation failure show that the present controlling standards need to be reviewed and improved to ensure the construction safety. Besides collecting more engineering data, centrifugal modeling test should be a helpful way to get more understanding about the soft foundation failure. A centrifugal test performed by authors is described. Some insights are drawn from this test: (1) as foundation enters shear failure state, foundation settlement takes a horse-saddle shape, i.e. the settlement under road shoulders being larger than that under road center; and slope toe horizontal displacement increases rapidly; (2) pore water pressure in foundation increases remarkably only after foundation has taken a large deformation; (3) the displacement velocity of foundation is basically in agreement with the value of controlling standard in construction regulation; (4) the ratio of horizontal displacement at embankment slope toe to settlement under road center, may be an acceptable standard in construction stability control.

The effect of stress history under three dimensional stress conditions are one of the important phenomena which have to be evaluated for the accurate prediction of ground deformation. Various stress-controlled drained monotonic shear tests on the Chinese Fujian standard sand of relative density 30 % under complex stress conditions with different stress paths are conducted using the soil static and dynamic universal triaxial and torsional shear apparatus. The mean principal stress is controlled unchanged in the process of tests. The stress history conditions are varied so that their influences on shear strength and stress-strain relationship of saturated sand are explored. Test results show that under drained condition sand specimens with stress history of different type do not change their shear strength for a given mean principal stress. On the other hand, the stress-strain characteristics behaved differently with respect to the stress history. The elastic locus varied with stress history has directional and stress condition effects. Finally, introducing predominant parameters for the difference of the direction and the stress condition between stress history and shear process, as well as taking into account the experimental results, the elastic boundary space due to the stress history is expressed under three dimensional stress conditions.

Based on a series of consolidated-undrained stress path tests, the mechanical characteristics of soft soil from Guangzhou Nansha under different consolidation conditions are systematically studied. The effect of initial consolidation on stress paths dependence of soft clay is analyzed; the characteristics of stress-axial strain relation and pore water pressure distribution under different stress paths are compared; and the connection of pore pressure and soil deformation state is discussed; the lateral unloading will induce shear dilatation of clay soil because of shearing stress increased and volume stress decreased. The test results also show that the effective stress paths under consolidated undrained shear is main related to initial consolidation; as a result the effective stress paths is only one under the same consolidated state. In addition, shear controlled mode of test has evident effect on the effective stress paths, but little influence on soil shear resistance.

An earth-rock dam is constructed with many layers and its core wall is unsaturated in construction period. The whole load of dam is divided into several increments for the calculation of stress and deformation. It is supposed that the increment is added instantaneously and then the dam is consolidated some times under the increment. Thus, the parameters for calculation can be taken from the consolidated undrained triaxial test. The characteristics of consolidation and stress-strain relationship and lateral deformation of test are presented. The law about the volume strain with time in consolidation process is discussed. The hyperbolic model for tangent Poisson ratio is also presented.

Based on the total Lagrangian description, the finite-strain finite element method (FEM) for foundation settlement is formulated and investigated from the viewpoint of the effect of geometrical stiffness (EGS). The soil mechanics sign convention was considered in the derivation of the FEM formulation. An illustrative example is used to study the EGS on the curve of load vs. settlement, and to analyze comparatively the EGS on the finite-strain FEM based on constitutive relations using different stress rates. The results indicate that: (1) the occurrence of EGS decreases the stiffness of the finite-strain FEM system for foundation settlement problems; (2) the ignorance of EGS will underestimate the values of simulated results, esp. for the case of large deformation; (3) the ultimate settlement predicted by finite-strain FEM based on the constitutive relation with Truesdell stress rate would be the same with that by conventional small-strain method, etc. The EGS of finite-strain FEM for foundation settlement plays an important role in accurate simulation, and should be treated appropriately. Any improper treatment of EGS would change the property of finite-strain analysis results with higher stiffness.

To evaluate the ultimate bearing capacity of strip footings on inhomogeneous soil foundations under combined loading accurately and to estimate the relevant factors which affect the ultimate bearing capacity are very valuable in engineering practice and significant in theory. Based on limit equilibrium theory and yielding criterion of Mohr-Coulomb, the application of the variational principle transforms the problem from its equilibrium equation format to a format of functional extremization equivalently which boundary value is undetermined. A nonlinear program, which is generated using VC++6.0, is used to achieve the function of the 2-D sliding surface and the failure envelope of strip footings on inhomogeneous soil foundation under combined loading. The friction angle of soil, the cohesive force, the shear strength ratio ci / ci+1 and the fluctuation of groundwater level, which affect the ultimate bearing capacity of strip footings on inhomogeneous soil foundation and the failure envelope, are studied theoretically. The results show that it is a certain upper bound minimum solution of the bearing capacity of soil foundation.

Vacuum preloading and vacuum combined with surcharge preloading used widely in construction put their vacuum location in the ground surface, and take out air from the top to improve the soft foundation; but that is not suitable to land reclamation. Vacuum preloading at the top and vacuum preloading at the bottom are simulated by laboratory test; then the properties of soil before and after test, axial settlement, drainage flow are analyzed to study the effect of vacuum location on the improvement of subsoil. The results show that the vacuum preloading at the bottom is better than vacuum preloading at the top.

From the viewpoints of considering the two effects of initial water content and rainfall intensity, infiltration velocity characteristics of expansive soil cut slope is studied through the field test. The results show that the water can infiltrate effectively only under the condition of successive rainfall in a certain intensity. The water content variety of slope is controlled by the successive time of rainfall, but not the intensity. The erosion amount is decreased with the reduction of water content. When the rainfall intensity is small, the rainfall makes little erosion on the slope surface. The erosion amount increases with the enhancement of rainfall intensity, but the value is gradually convergent. When the slope is covered by vegetation, the permeability is strengthened, but the erosion scale is lightened greatly.

The scattering of SH-waves by a shallow buried cylindrical elastic inclusion with a partially debonded curve in half space is studied by function of complex variable method. Firstly, the standing wave function in the cylindrical elastic inclusion is constructed, where satisfies that the stress on the debonded curve is zero. Then the function is generated into the Fourier series. In the half space, the boundary condition of the medium satisfies that the stress on the debonded curve is zero and the stress and displacement on the common border are continuous with the elastic inclusion. Then, a set of infinite algebraic equations to solve this problem can be obtained. In the end, numerical examples of the surface displacement are presented. The results indicates that the surface displacement could be influenced by the incident wave parameters, the position of debonded curve, the parameters of elastic inclusion and the depth of the buried inclusion to some extent.

Mechanical behavior of soil-concrete interface is essential to soil-structure interaction; and it is necessary to understand it properly during numerical simulation. Negative shear tests using laboratory simple shear apparatus are performed on soil-concrete interfaces with three water contents, namely 17 %, 20 %, and 24 %. Five normal stresses and four previous shear ratios are taken into accounted in each water content. Experimental data show that while water content and previous shear ratio are fixed, failure of negative sheared interfaces still satisfy the Mohr-Coulomb criterion. After experiencing shear with 0.5, 0.75 and 1.0 previous shear ratio, shear strengths of the negative sheared interfaces become 90 %, 75 % and 55 % of those of original interfaces respectively. At the same time, cohesion forces of the negative sheared interfaces become 95 %, 80 % and 54 % of those of original interfaces, and friction angles of the negative sheared interfaces become 90 %, 76 % and 57 % of those of original interfaces respectively. This experimental research is useful for relative engineering numerical simulation.

Assuming that the back-filled grouts are Newtonian fluids, and the grouts diffuse with cylinder surface, the grouts diffusion radius and the pressure to shield tunnel segments in case of grouting at the tail as well as through segments, are studied by substituting the intrinsic void percent with the equivalent void percent of the soil to consider the influence of construction gap. As a result, the formula used to calculate the radius and the pressure are acquired. It is shown that the grouts diffusion radius and the pressure to segments are related to many factors, such as the grouting pressure, grouting time, characteristic of the surrounding soil and the grouts, etc. It is also shown that the pressure to the segments produced by grouting at the tail is less than grouting through segments. With other parameters known, the relationship between the grouts diffusion radius, pressure to segments, and the grouting pressure, grouting time is discussed by an engineering example, which shows that both the diffusion radius and the pressure to segments increase with the increase of the grouting pressure and grouting time, but their speeds are different.

The preconsolidation pressure ( ) is an important parameter in soil mechanics. For conventional unfrozen soils, is an index of the loading history and has close relationship with mechanical properties of soils; for frozen soils, special structure exists due to the interaction of ice and soil grains. Similar index like the preconsolidation should exist in frozen soils. A clay obtained along the Qinghai-Tibet Railway is taken as research object. compression tests are carried out on remolded soil samples with a wide range of dry density under different negative temperatures. Double logarithmic coordinates are used for obtaining the preconsolidation pressure of the frozen soil. The testing results show that the preconsolidation pressure of the frozen soil is related to the initial dry unit weight of the frozen soil, while temperature is more dominant.

According to the results of tests in laboratory and in-situ under different weather conditions, the geotechnical properties, some laws of different dry densities and original water content shear strength properties and penetration-resistance of static cone sounding of in-situ of the powdered soil of coal measure strata are discussed emphatically. Some important critical indices of the powdered soil of coal measure strata are put forward. And the empirical formulas with practical value are given. The research results would provide theoretical reference for evaluating properties, roadbed treatment and slope treatment of the powdered soil of coal measure strata.

The treatment and disposal of dredged sediment is one of the main environmental problems; and the valorization technique has potential application in engineering practice. By means of the proposed chemical treatment technology, heavy metals existing in dredged sediments can be chemically stabilized to insoluble metallic phosphates by adding H3PO4; the organic content can be remarkably reduced by thermal treatment; the physical property of treated sediment can be improved by adding FeCl3. The effect on the physical, mechanical and thermal properties of dredged sediment is investigated based on the laboratory tests on samples of different contents of additive reagent. The results show that the mobility of contaminant in dredged sediment is significantly decreased, and the treated sediment can be a kind of potential construction material.

A new type of retaining and protecting structure called squeezed pan pile in double-row is introduced; and then its compaction efficiency, loading transfer behaviors, characteristics and the calculation method are discussed. Squeezed pan piles in double-row are indicated that its stress system is similar to a special frame structure through model test and numerical simulation. Compared with the cantilever reinforced concrete retaining straight piles, the major characteristics of squeezed pan piles in double-row contain: (1) The space rigid is increased enormously; the displacement in top of piles can be reduced greatly. (2) The stress system is proper; bending moments are alternating distributed; the maximum bending moment is decreased. and (3) The embedded depth can be shortened; retaining height can be enhanced; the material of piles can be utilized sufficiently. It is concluded that the squeezed pan piles in double-row have many significant advantages including advanced technology and little risk. It will provide a more reliable method of retaining and protecting for foundation excavation.

A study of swelling properties of bentonite-sand mixture is presented. A series of swelling tests is conducted on the mixture. Based on the experimental data obtained, the relationships between swelling strain and axial stress, swelling strain and water-absorbing volume, axial stress and water-absorbing volume are analyzed. Then, a swelling constitutive equation of the mixture is brought out, which reflects the influences of axial stress and water-absorbing volume on swelling strain. The results show that the swelling strain increases with water-absorbing volume increases, but decreases with axial stress increases. The water-absorbing volume decreases with axial stress increases. For a given value of axial stress, water-absorbing volume has a maximum value at the end of swelling process.

Soil preconsolidation pressure is an important index for determining the consolidation status. The foundation settlement calculation formulas are different as on various consolidation statuses, so it is very significant to determining preconsolidation pressure precisely. First the imperfectness of normal parametric models for determining the max curvature point of the fitted e-lg(p) curve is analyzed; then the cubic smoothing spline which is a nonparametric model used for fitting is proposed; the calculation results show that this model is more adaptive to experimental data and the fitting result is more precise. Base on the Casagrande’s method of determining the preconsolidation pressure, the corresponding program “PCP Calculation” is then developed by MATLAB; the program has a friendly interface and can draw figure exactly; and the calculated results are satisfactory.

An experimental research on a model pile embedded in a deposit of submerged silt has been carried out under lateral static loadings. The 6th order polynomial function was selected to fit the tested results and back-calculate the lateral soil reaction p and lateral deflection y. Thus, the silt p-y curves and theoretical p-y curves formulation accounted for both angle of friction and cohesion component were proposed and compared with the API recommended ones for sand and soft clay, respectively. The results indicate that the cohesion component has great effect on the p-y curves, neglecting the soil resistance from the cohesion component, sometimes will lead to a significant conservation pile foundation design in the case of silt. And the predicted bending moment responses of the model pile using these silt p-y curves are in good agreement with the experiment results.

The direct shear tests with controlled suction, water content and dry density equaling constants were conducted to study the effects of suction,water content and dry density on the shear strength of remolded unsaturated soil. The test results show that the cohesion of unsaturated soil has a linear increase with the increasing of suction; but the friction angle has little change with the change of suction. The cohesion and friction angle of unsaturated soil have a linear decrease with the increasing of water content; but the cohesion decreases more. The cohesion of unsaturated soil has an exponent increase with the increasing of dry density; but the friction angle has little change with the increasing of dry density. The comparison of the test results with controlled suction and water content equaling constants is carried out. The shear strength formula including impact of water content is proposed, which can be for reference in engineering application.

Unconfined compressive strength tests and direct shear tests were conducted to cement solidified dredged material (SDM) and remolded solidified dredged material(RSDM). The stress-strain curves and unconfined compressive strength and cohesion and internal friction angle of SDM and RSDM were compared and analyzed. Test results show that the brittleness of SDM increase but the plasticity deduce. However, the cement content and curing time do little effect on RSDM, the stress grows slowly while the strain increase, the plastic deformation is great. The unconfined compressive strength and cohesion of SDM gains with cement content or solidified curing time increases, however the internal friction angle knock down. The unconfined compressive strength and cohesion of RSDM reduce a little comparing to SDM, the more the cement content and curing time longer the reduction is larger. The internal friction angle of RSDM increase as the cement content and curing time become gains. The unconfined compressive strength of RSDM largely comes from friction effect among the crushed solidified soil mass.

The existing of voids is the nature characteristic of the porous media, which not only alters the mechanical character of the rock masses, but also affects their permeabilities. Most of the porous media models in the past regard the porosity and permeability coefficient as the constant which were irrelevant to the time constant. In fact, they varied with time and coordinates due to erosion, and other reasons. At the same time, the porosity and permeability coefficient were relevant to the pore pressure and velocity of the porosity water. From the continuum damage mechanics point of view, the mechanical permeability properties of the porous media were studied based on the quantitative relationship between the porosity rate and the damage variables. First of all, the traditional Darcy law was modified, and the complete effective Darcy law (model) inside the complete and effective seepage field in porous media was derived. Then, the model’s properties of permeability parameters were discussed and analyzed. Finally, some useful and valuable conclusions are drawn.

Deformation behavior of bored pile wall is analyzed based on a database of some 80 case histories of deep excavations in Shanghai soft deposit. The maximum lateral deflection of bored pile wall ranges from 0.1 % to 1.0 % of the excavation depth, with a mean value of 0.44 % of the excavation depth. The location of the maximum lateral deflection of wall occurs 5 m around the excavation surface. No significant difference of wall deflection was observed between the concrete strut group and the steel strut group. Normalized maximum lateral deflection of wall decreases with increasing the system stiffness, while increases with increasing the thickness of soft soil above wall toe. Neither depth ratio nor factor of safety against basal heave has significant effect on maximum lateral deflection of wall. Lateral displacement of top of wall increases exponentially with the depth of the first level strut. However, location of the first level strut does not have significant effect on the maximum lateral deflection of bored pile wall.

The bucket foundation breakwater is a new type of structure applied to port and coastal engineering; of which the stability is sustained by the bucket foundation penetrated in soft soil. In terms of a practical project, a 3D elasticplastic finite element model is established for stability analysis of the bucket foundation breakwater; and it is shown that the instability mode is rotation of the bucket foundation breakwater around a point below foundation base. Through analysis of forces on the structure in limit state, a stability calculation method based on the actual rotation point is set up. The stability calculation model and calculation formulas for soil forces, etc., in the model are tested by comparing with the results calculated by finite element method. On this basis, a simplified calculation method for the bucket foundation breakwater founded on the stability checking mode of gravity structure is established by moving the rotation point to the foundation base as the imaginary supporting point when the structure is overturning. And the horizontal distance between the imaginary supporting point and the central line of the structure is expressed as h′, the value of which is suggested by analyzing the results calculated in different foundation scales. In comparison to finite element method, the results indicate that the simplified method has high accuracy and could be a reference for practical projects.

A simple two-stage method for estimating the longitudinal deformation of existing tunnels caused by adjacent excavation in soft soils is presented. In the first stage, the Loganathan and Poulos analytical solution is used to estimate the free-soil settlement induced by adjacent tunneling. The additional stress due to adjacent foundation pits excavation is calculated based on the Mindlin solutions. In the second stage, existing tunnels are considered as beams with infinite length based on the Winkler foundation model. The free-soil settlement or additional stress is then imposed to the existing tunnels. Displacements and internal forces of the existing tunnels are obtained. Finally, the accuracy of the proposed method is verified with centrifuge model test data and engineering case studies. The proposed method may provide a theoretical basis to establish rational protective measures of the existing tunnels influenced by adjacent excavation.

The Xuefeng Mountain tunnel is the largest controlling project of Shaoyang－Huaihua Expressway in Hunan Province which belongs to the Shanghai－Ruili National Key Highway. The length of the tunnel is about 7 km and the largest thickness of its overlay is about 850 m. It is a typical thru-mountain long highway tunnel. Several different methods were used to predict the geologic disaster and stability problems of the tunnel，such as fault, rockburst, large deformation of surrounding rock, etc. Based on geological analysis, methods such as TSP, geologic radar, projection and key block search method, mechanism of fault movement, testing of surrounding rock stress, etc. were applied to forecast the geologic information in tunnel facing frontage; and good effect was achieved; especially the successful prediction and forecast of F2 appearance and zero possibility of strong rockburst. This provided guarantee for the tunnel safety construction，and a good example for other similar projects.

Based on the successful in-situ ground improvement experiment and large-scale practice of a harbor container terminal in Shanghai, by innovative and modified construction techniques and parameters, the effectiveness of vibroflotation compaction without additional backfill materials in filled saturated silty fine sands is investigated. The variety of soil deformation and excess pore pressure, techniques and parameters, improvement effectiveness have also been analyzed and discussed. The in-situ test results show that the vibroflotation compaction without additional backfill materials can significantly strengthen deep silty fine sands. It can significantly improve the densification and remove the damage of differential settlement and liquefaction. The results further broaden the application range of vibroflotation and provide great practical value for some other similar projects in the future.

The concept of coefficient of slice stability is proposed for the limitation of the definition of factor of safety in traditional slice method. Some effect factors are analysed to the height of thrust line, an assumption is advanced that the stability coefficient of inter-slice forces is equal to the same value , and the eccentric moment of slice weight should be considered in the analysis; the four variables equations are established based on the balance of forces and moment and the assumption of inter-slice forces; then the stability coefficient of every slice and its distribution along the slip surface can be obtained. According to the distribution of slice stability coefficient along the slip surface the slip mass can be divided into main slide sector and trailed sector and anti-slide sector; and then the sliding model of the slope can be judged; the factor of safety of the slope stability is also defined by the ratio of the sum of anti-sliding force to the sum of sliding force on the slip surface. Two examples are analysed by the traditional slice method and the slice-stability method; the result shows that the slice-stability method is more reliable.

The Yingbin Avenue trench slope being designed is adjacent to the existing Jingcheng railway 21th tunnel, the tunnel will suffer a bad affection when the slope be excavated. A numerical analysis of statics and dynamics according to the rock and lining parameters from the field test has been undertaken. This paper studies the maximum extension of slope which can be excavated and the influence of tunnel on slope blasting vibration. The result indicates while the distance between the base of second slope and tunnel center line is larger than 30 m, the inner force of tunnel lining will increase but the structure still in safety state when the second slope be excavated; and when we excavate the slope by blasting method, if we consider a triple safety factor, and while the vibration velocity is smaller than 1.5 cm/s, the dynamic tension stress of the 21th tunnel lining is smaller than its ultimate value; and therefore we can undertake field monitoring by the reference control vibration velocity.

For the design of impervious lining system of seepage tunnel, load-structure method and crack limit verification method are mostly recommended in China. However, the impervious design criteria is proved to be unreasonable for high pressure concrete lining system resulting in an over estimation of steel ratio. Thus, the research on a reasonable and safe permeable design for concrete lining of seepage tunnel is necessary. But, the suitable criterion is not confirmed in the design of high pressure hydraulic tunnel. Based on body force theory, a method of FEM is presented to design the permeable lining in high pressure hydraulic tunnel. The method can simulate the construction and security operation and repair process of the tunnel. The direct coupling of seepage field and stress field may be analyzed. Then, it is used in a real project. The crack width of concrete and the reinforcement of lining can be calculated by means of internal force. By comparison of the reinforcement, it is demonstrated that the results are satisfactory and the presented method is reasonable and effective.

Through deeply researching the formation of complex structures and a variety of impermeable materials, the suitable construction equipment and improved technology are seleted. During the trial on the basis of the analysis, based on different strata to determine the construction of scientific control parameters; and further on the two-storey high-permeability zone to take a simple filling of deep plugging engineering measures to achieve the desired effect of anti-seepage. By statistically analyzing the sandy gravels from the basin of the Jialing River and Bailongjiang formation and several other engineering examples, their anti-seepage coefficients are about K >1×10-4 cm/s; and the complex high-permeability strata by calculating and pumping test analysis to verify, K <5×10-5 cm/s. Finally, an alternative, 2-hole single-row or three rows of double-row nozzle at high complex formation in the construction process control measures and filling plugging measures is suggested to deal with the success of the project application; and it will be available for similar projects.

The fractal geometry is the theory used in the field of studies of the nonlinear phenomenon which has been developed since 1970s. Based on the theory, the fine structures hidden in the chaotic and complicated phenomenon have been described quantitatively. The method of fractal has been taken into the research on the advance geological forecast of tunnels ;and the rock mass quality has also been predicted by the fractional dimension of the net of the rock mass structural plane. Combining the theory with the practical constructions, some conclusions have been drawn: the fractal characteristics of the rock mass structure are obvious; and the fractal descriptions can be used as the criterion to evaluate the rock mass quality. Therefore, the fractal method is an effective method for evaluating the properties of rock masses; and it has the extensive using prospect.

Dry mixed cement gravel pile is a rapid, uncavated embankment new technology. It is applied on the embankment of Xuchang-Luohe Section of Beijing-Zhuhai Expressway. The length of the testing pile is 5.0 m, with 150 mm diameter, the interval between piles is 1.0 m×1.0 m; and height of filling mater is 25 cm; and it is tamped with 120 kg rammer, ≥1.0 m length of hammer ramming space. Three plate loading tests have been carried out with the pile of 10, 8, 7 pound per layer respectively; heavy duty dynamic sounding tests have been done with the pile of 8,7 pound per layer. The results show that the pile with 7 pound per layer of which the ultimate load capacity is 400 kPa is the best. Through geological radar and lab testing, valid unit weight added and water content reduced after construction. Embankment diseases have not been detected after they were treated one year, so it is shown that the pile is effective in treatment expressway embankment.

Saturated-unsaturated seepage theory is applied to calculate seepage in riverside foundation pit; and the seepage stability of the foundation pit is evaluated; also the best anti-seepage measures and corresponding parameters of this foundation pit are determined. The results show that the slope soil of foundation pit is instable without anti-seepage measures, so that the anti-seepage measures must be adopted. The steel sheet piles are adopted from the perspectives of convenient for construction; it is located at about 6.0 m distance to the foundation pit’s right slope. The length of steel sheet pile has remarkable effect on the seepage field; they should drill through silty sand layer, thus can play a better anti-seepage effect, so as to benifit the stability of foundation pit slope. In addition the steel sheet pile should not too long, because increasing the length of steel sheet pile not only waste materials, but also the effect is not better; the best length is 15.4m.

Under deep mining, according to the modified rock quality designation(RQD), namely, the different rock groups are classified as different lithologic characters at first; then three-dimensional RQD is measured as the corresponding rock groups. By using the method of accurate measurement along three-dimensional routine lines, the RQD of the three-dimensional surrounding rockmass in the tunnel headings at Kongzhuang Mine is figured out and statistical analysed. Based on these results, the jointed rockmass strength reduction coefficients are obtained; and the engineering rockmass equivalent strength is calculated as reduction formula to the rock uniaxial compression strength. The research findings are good to the quantitative assessment for the rockmass structure character; and it is a new method to define the deep rockmass strength properly.

Based on the features of acoustic emission(AE) time series monitored for rockburst, adopting the wavelet neural network and catastrophe theory, a new rockburst prediction model is established. Firstly, a wavelet neural network model based on the AE monitored is established to forecast the future AE. Secondly, a catastrophe prediction model for rockburst is founded based on AE forecasted. A practical example shows that the predicted AE time series has high prediction accuracy; and rockburst prediction are consistent with field situation. It is shown that the model has the advantages of high forecasting accuracy and strong practicality.

The stability of the dam-abutment is reflected synthetically by its deformation observation. The small deformation of the dam-abutment is continuous in working period and its influence factors have time-varying characteristic. Therefor a spatial-temporal series forecasting model is presented combining with regression model and multilayer recursion analysis method of dynamic system in this paper. The model syncretizes the strongpoint of regression analysis and recursive analysis and enhances the capability of forecasting evolution of the arch dam-abutment deformation. The engineering case analysis shows that the model is effective and applicable. There is a considerable merit for forecasting arch dam-abutment deformation to take into account time-varying effect of dam-abutment status.

Compatible distortion method of structure of pile-anchor is a key point in internal force computing of structure of pile-anchor. The present method is derived from a hypothesis that the distortion of the pile is very small, or even can be ignored. Thus the method can be used only when the prestressed force of cable is very small or null. But in a lot of engineering case, the prestressed force of cable is significant and the distortion of pile can’t be ignored. So, the hypothesis of present method is not in accordance with the working condition of the structure of pile-anchor. Based on studying on the two steps of distortion process, the present method is improved with structural mechanics theory in two aspects. Firstly, the calculating method of the distortion and rotation in the slipping surface is modified. Secondly, the formula which is used to count the distortion made by the anchor on the j row to the i point on the pile is improved. An example is given to prove that the improved method is more useful to the engineering design.

In order to investigate the influence of pore gas pressure on the coupled thermo-fluid-mechanical processes in geological disposal of high-level radioactive nuclear waste, a 2D elastoplastic FEM code was developed by using the model of non-isothermal air flow and water flow in a deforming porous medium suggested by R. Leiws et al, in which an item of thermal water diffusion was added by the author. Against an assumed model of geological disposal of nuclear waste, the numerical simulations in which three kinds of original pore gas pressure in the buffer were applied, were carried out under the conditions of the same initial temperature, pore water pressure and in-situ stress. The distributions and changes of the principal stresses, saturations, fluid flow velocities, pore pressures and temperatures in near field of the disposal model were analyzed. The results show that the higher original pore gas pressure in the buffer gives a bigger effect on the stresses in rock.

Three-dimensional finite element coupling numerical model is used to simulate the bearing behavior of pile foundation from low-cap to high-cap with fluid scour; and a reasonable simulation is drawn. The simulation has some reference value for the problems of fluid scour and numerical simulations of excavation about pile-soil interaction. Combining an engineering example, it is found that the calculation about the effect of scour on the pile foundation is inaccurate, if it just be considered simply as high-cap. At last, the variation law under different conditions are analyzed by changing the contact element and soil element stiffness. The results show that the rebound effect by the fluid scour couldn’t be neglected during the engineering calculation.

The relationship between thermal conductivity of porous material and fractal dimension is numerically simulated by using finite element method. The solid matrix and pore space are generated randomly according to material porosity；and material parameters and element properties are changed by ANSYS parameter design language. The effective thermal conductivity is computed according to thermal flux through some section computed by FEM and Fourier heat transform law. The investigation shows that the effective thermal conductivity linearly decreases with increasing porosity; the effective thermal conductivity of FEM model will increase in exponential function with the increase of scaling factor while the material porosity is constant. The effective thermal conductivity will decrease in exponential function with the increase of fractal dimension of porosity space and increase in exponential function with the increase of fractal dimension of solid matrix

The basic components of solid cellular automaton were defined in three-dimensional condition. The theories of elastoplasticity, cellular automaton, statistics and rock mechanics are integrated to develop an elastoplastic cellular automaton model to simulate the failure processes of heterogeneous rocks under three-dimensional condition and the associated numerical code EPCA3D was compiled in Visual C++ environment. The EPCA3D code was used to simulate the failure processes of heterogeneous rocks under uniaxial compression. The failure mechanism was well explained by analyzing failure pattern, inner failure position, complete stress-strain curves as well as the acoustic emission. It is found that the EPCA3D has the ability to simulate crack initiation, propagation and coalescence in the failure processes of rocks. Using the developed model, the effect of confinement on the complete stress-strain curves is investigated by using the linear combination of stress and strain loading control method. It is concluded that brittle heterogeneous rock is prone to behave Class II with small confinement and behave Class I with big confinement. The strength of the rock is lower with smaller confinement and vise versa, which is consistent with the results obtained from physical experiments.

A mixed finite element method for miscible contaminant transport (mass transfer) process in saturated porous media is presented. The governing mechanisms in contaminant transport model contain convection, mechanical dispersion, molecular diffusion and adsorption. The displacement, strain and effective stress in solid phase; pressure, pressure gradient and Darcy velocity in liquid phase; contaminant concentration, concentration gradient and its flux are treated as independent variables. The variational (weak) form of the governing equations is given on the basis of the extended Hu-Washizu three-field variational principle with particular consideration of the characteristic-based algorithm in eliminating spurious numerical oscillations in solving mass transfer process. The numerical results illustrate good accuracy and efficiency in comparisons with the existing standard four-point quadrature.

High fill culverts have been widely used in expressway in mountain area and problems of culverts frequently take place because of improper ground treatment. Field test and FEM numerical simulation were carried out to investigate the stress state of the culvert and ground, as well as the deformation characteristics of the ground. The effect of stiffness and uneven settlement of ground on the stress state of culvert and embedded depth on the ground bearing capacity are discussed. The research results show that the pressure of subgrade of culvert is close to that of the roadbed at the same elevation, which can be regarded as equal pressure in design of foundation. The stiffer the ground is, the higher the vertical earth pressure on the top of culvert will be. So a higher strength of culvert is needed and the application of rigid pile in ground treatment of culvert under high embankment should be avoided. In addition, the design method for foundation of culverts under high embankment is proposed based on the research results.

As a commonly used dynamic integration analysis method of earth-rock dam, Wilson-? method has comparatively low accuracy in analyzing problems involving high frequency and long time interval. Aiming at the disadvantages, an improved quadratic acceleration integration method is put forward. Compared with the one step quadratic acceleration integration method, its numerical accuracy remains the same and the requirements of stability are more easily satisfied but the time needed in calculation is reduced sharply. And then, the fundamental, stability and accuracy of the method are analyzed. Moreover, a case study about the earth-rock dam dynamic analysis is given to prove the feasibility of the method. At last, by comparing the results of the proposed method with those of Wilson-? method, Newmark method and Central difference method, the numerical accuracy has been analyzed. The results indicate that the proposed method is highly accurate in analyzing problems especially in high frequency and long time interval.

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Based on virtual internal bond model (abbreviated as VIB) for isotropic materials, and enlightened by the similarity of the damage constitutive model of rock under uniaxial compression and the cohesive force law of VIB, a virtual internal bond density evolution function of rock under uniaxial compression is suggested; and then the elastic tensor is formulated. Finally, it is successfully to simulated the complete curve of rock under uniaxial compression. The simulation results show that the VIB model can simulate different kinds of rock sample if the parameters are selected well.

The authors give a comprehensive derivation of the concrete damaged plasticity model in ABAQUS, which is based on the damage mechanics and can describe the damaged mechanism of concrete during unloading in postfailure stage through introducing a damaged variable. The constitutive model can consider the stiffness degradation and strain rate under cyclic loading condition which is suitable for the analysis of concrete and other quasi-brittle materials, such as rock, mortar etc. In order to verify the feasibility of applying it to underground structures, a time-history dynamic nonlinearity analysis is achieved for a hydropower station underground structure which mainly considers the influence of different compression stiffness recovery factors and strain rate dependence to the damage of concrete and surrounding rocks. The simulation results indicate that the damage of underground structure is a progressive procedure; the rate dependent effect doesn't immediately occur at the beginning of earthquake but gradually behaves after the understructures have undergone some damage. The results also prove that the damaged plasticity model is dramatically competent for the dynamic nonlinearity study of underground structure during seismic loading especially under strongly seismic loading. The conclusion could be used as a primary guidance to the anti-earthquake design for practical engineering.

Based on the extended Mindlin solution of a vertical point load in the interior of a layered elastic medium, boundary element method is used to analyze an axially loaded pile in a layered soil system. The method to deal with the singularity of fundamental solution has been improved. The influence of the compressibility of pile and the ratio between length and diameter on the load transfer between pile and soil and the settlement pile foundation are taken into account. Numerical calculation and analysis indicate that good and reasonable results can be acquired using the method presented.

For actual engineering, the aquifers are generally three dimensional anisotropic problems, aiming at the computing time too long and local optimization limitation of conventional method, a new method of three dimensional seepage parameters identification based on support vector machine and particle swarm optimization is proposed. Adopting orthogonal experimental design and finite element program producing training samples, using SVM mapping, the nonlinear relation between water heads and seepage parameters is established. Then taking error objective function as the fitness value of particle swarm optimization, the seepage parameters should be identified by PSO. The method can directly utilize the large scale seepage finite element program. The computing example is given to prove that the method has favorable efficiency and precision.

In order to reduce the cost, the GPS with multi-antenna highway steep slopes real time monitoring system is established according to the idea that the single GPS receiver links multiple antennas. The system consists of field collection subsystem and indoor control subsystem. The collecting GPS signal from antenna array of the former is transmitted to the latter through time-sharing instrument, signal amplifier, wireless router, WLAN antenna; and the monitor points’ coordinates are computed by data processing. In the single epoch algorithm, the non-integer solution of the ambiguity can be calculated from double difference value of satellite-earth , double difference value of carrier phase and wavelength because the sampling of GPS is dense and the deformation value of monitor points between the twice samplings is small commonly; and then the integer ambiguity is obtained by ROUND function. Thus, the positioning precision of the double frequency receivers’ carrier phase can attain ±5mm. It not only meet the requisite precision of steep slopes real time monitoring of highway, but also solve the problem of cycle slips which is brought from the switch of GPS signal between different antenna channels; thus the data processing can be simplified.