The damage area is much larger than the blasting excavation area, so rock mass would be damaged several times and result in accumulative damage. The left bank diversion tunnel at Wudongde hydropower station is monitored and simulated for blasting vibration and rock mass deformation during excavation. Based on accumulative damage theory, the damage threshold and damage variable are adopted to consider the parameter weakening in different damage areas. The weakened rock mass parameter is adopted in each damaged element, and numerical simulations are conducted to simulate the accumulative damage induced by blasting excavation. By comparing monitored data and calculation results, the results considering accumulative damage is more close to the monitored values of both blasting vibration and rock mass deformation. Therefore, in numerical simulations of blasting excavation of tunnels, accumulative damage effect should be considered.

To investigate the coupling properties and laws of the deformation and the shear strength of fresh municipal solid waste (MSW), the compression-direct shear combined tests have been carried out by using large-scale combined test apparatus of compression and direct shear. Ninety-six fresh municipal solid waste samples were prepared in geoenvironmental laboratory. The initial void ratios of the samples were selected as 2.1, 2.5 and 2.9. Four different vertical pressures 25, 50, 100, and 200 kPa, were chosen; and the compression times for every vertical load were 0, 0.25, 0.5, 1, 2, 6, 12, and 24 hours, respectively. The testing results show that: (1) The relationship between shear stress and shear strain under different compression times is in conformity with a hyperbolic model; model parameter a varies from 0.028 to 0.144; and model parameter b varies from 0.012 to 0.024. (2) A multinomial model can be used to express the relationship between shear strength and compression strain (compression time) under different vertical pressures and different limit values of shear strain, the values of model parameters are given, and the correlation coefficient of the model is found in the range of 0.63-0.98. (3) The relationship between shear strength and vertical pressure applied on the sample under different initial void ratios complies with Coulomb’s law. Besides, shear strength parameters of the MSW are obtained; the cohesion force varies from 11.1 to 34.2 kPa; and the internal friction angle varies from 11.2 to 30.6 degree.

To truly describe the reaction of saturated sands under cyclic loading, a parameter considering macroscopically dilatancy stage on fabric changes is necessary. Based on the existing constitutive model dependent on a state parameter, a fabric-dilatancy internal variable z considering the influence of the fabric change is introduced. It is still based on phase transformation state. With state parameter the deformation tendency of sand at any time or any conditions can be judged. Through the z effected on the dilatancy, plastic deformation accumulation is considered when load increment reversals. In this paper, an elastoplastic constitutive model of saturated dense sand under cyclic loading is established. According to experimental phenomenon analysis, plastic modulus in the existing model is modified, it can simulate well expansion shrinkage change process of sands under drained cyclic loading. Finally, in view of the dense sands during triaxial drained cyclic loading, a comparison between model simulations and a sequence of experimental results shows that the model can generally reflect the deformation behavior of being given sand.

Mechanical characteristics of saturated argillaceous dolomite under freezing–thawing cycles were tested by low temperature numerical control incubator BCD-218 C and computer-controlled electronic versatile testing machine WDW3100. In uniaxial compressive state, characteristics of stress–strain curves and law of peak stress, peak strain, elastic modulus and Poisson's ratio varying with freezing-thawing cycles were analyzed. Base on existing theory of damage mechanics, damage constitutive model of taking freeze-thaw cycle times and strain as control variables were established by introducing slope increase trend coefficient (correction coefficient). The results show that peak stress, peak strain and elastic modulus decrease exponentially; while Poisson's ratio increases linearly with increase of freezing-thawing cycles. For the effects of freezing and thawing cycles, the short line shape gentle stage appears after the first stage (compaction stage) in complete stress-strain curves, during this period, the rock shows partial slippage phenomenon. In addition, failure mode of the rock transforms from brittleness to ductility, which has pre-peak plastic hardening and post peak strain softening behavior. Theoretical constitutive model coincides with experimental results.

In light of the present situation of engineering rock mass stability control problem caused by strength deterioration of rock under wetting-drying cycles, taking the coal seam roof No.8 medium grained feldspar quartz sandstone of Baode coal mine in Xinzhou, Shanxi province, China, for example, modified tests by organic silicon material were carried out. The strength damage and deterioration rules of sandstone for modified and unmodified under different wetting-drying cycles were studied by uniaxial compression tests; the change rules of surface zeta potentials of sandstone for modified and unmodified were comparatively analyzed by electrophoresis; and modification mechanism of organic silicon material modified sandstone is discussed. The results show that: (1) The uniaxial compression strength (UCS), elastic modulus (E) and deformation modulus (Ed) of sandstone samples are increased obviously by modification, and raising the UCS, E and Ed of sandstone samples by 2.17%, 22.2% and 23% respectively. (2) The strength deterioration effect is obvious under wetting-drying cycles; and the UCS, E and Ed of sandstone samples decrease by negative exponent relationship with wetting-drying cycle times increase. (3) Organic silicon material greatly affects the surface of electrical behavior of sandstone; with the pH values of sandstone suspension samples decreasing, the surface electrical potential of sandstone varies from electronegative to electrically neutral and to electropositive in the end.

Considering the factors of static buoyancy and dynamic buoyancy, time variation of grout and compression of the overburden soil, based on curved differential equation of elastic foundation beam, finite element theory, boundary conditions and the coordination equations for deformation, angle rotation, shear and bending moment, a theoretical solution for longitudinal upward movement of underwater shield tunnel is obtained. It was applied to comprehensive pipe Project of Caofeidian Industrial Zone Gallery known as ‘the 1st shield of Hebei. The computation example of engineering shows that the maximum error of theoretical solution and numerical solution is within 2.5%. Furthermore, the result obtained by the proposed theoretical solution is well consistent with the monitoring result of normal excavation section and can be used to analyze the longitudinal upward movement of shield tunnel. Moreover, the theoretical solution has got rid of the tedious process when numerical model established and unit refined, so it will be accepted more easily by constructers or designers, so as to provide some reference to perfect the related design specifications.

In order to further clarify the effect of particle breakage on strength and deformation of soft rock coarse aggregates, consolidation drained triaxial shear tests of two groups of different initial dry densities of sericite schist coarse aggregates are carried out. The law of particle breakage and its influence on mechanical properties of sercite schist coarse aggregates are discussed. The result shows that the relative particle breakage index of sercite schist coarse aggregates increases with confining pressure. But the growth rate of particle breakage is greatly influenced by the initial dry density. The relationship between particle breakage and confining pressure might be described by a linear function. The particle breakage of high density samples is significantly higher than low density samples under the same stress level because of the influence of the initial porosity. So influence of particle breakage on shear strength decrease under the high density is higher than the influence of low density samples; this might cause stress strain curve of two different dry densities to intersect somewhere. Finally, the shear strength of low density is greater than the high density samples. The porosity of high density sample is small and its dilatancy factor always stay near 1.The porosity of low density sample is larger and the particle breakage and dilatancy delay the impact on its dilatancy factor. So the lower density of samples, the larger volume change is. However, the volume change is very small because of the influence of particle breakage and dilatancy of sericite schist coarse aggregates.

To investigate the mechanical properties of shale under different strain rates, then to provide scientific guidance for the exploration of shale gas, the uniaxial compression experiments of shale samples have been conducted under strain rates of 5×10-4/s, 1×10-4/s, 1×10-5/s and 1×10-6/s, respectively. The experimental results show that the strain rates affect obviously on elastic modulus, peak strength and fracture morphologies, etc. of shale. Elastic modulus and peak strength gradually decrease along with the inclining of strain rate from high to low, but the decreasing speed becomes gradually smaller and smaller. The fitting relationship of elastic modulus (also peak strength) versus minus logarithm of strain rate largely adapts to the power function, whereas a higher fitting degree occurs if the mean values are implemented. Relatively speaking, the elastic modulus has a higher strain rate reaction. The fracture modes are obviously affected by the strain rate: under high strain rate, sample rapidly split into several large pieces and the entire skeleton ruptured; with the decreasing of strain rate, the fracture mode gradually transfers to main splitting failure with local shear failure; under the lowest strain rate, the main fracture mode is still splitting fracture but with many transverse cracks inserting the lateral surface; that is to say, the fracture mode under lowest strain is characterized by occurrence of cracks-net. In a word, the strain-rates affect the fracture morphologies most obviously, which performs mainly the relatively mean fracture and cracks net. Thus, these features of strain rate effect can provide important enlightenment for the parameters determination and hydro-fracture plan-design of shale.

The pile-plank structure, as a composite foundation for roadbed treatment in goaf, is still being held up by lack of recommendation and regulations. In order to study the behavior of this structure, the example of the Wufushan station in Hefei-Fuzhou high-speed railway was researched by model test; and then a series of data of pile axial force, soil pressure, and settlements of pile, bearing platform, soil, and goaf roof was obtained. Based upon the results of these data, an analysis of the variations of pile axial load, soil pressure, and settlement characteristics of this structure was conducted. Some conclusions are drawn as follows. (1) Under the effect of overlying load, the value of pile axial load presents a decrease as the increase of depth with its maximum appeared at the top of pile. The pile axial load along the sections distributed in goafs maintains constant as the increase of depth. (2) As the increase of depth, the skin resistance of pile also reduces along pile without negative value presented. The value along the sections in goafs is zero. (3) The variation of pile-soil stress ratio is similar to that of pile-soil load share ratio. The load shared by the pile firstly presents an increasing trend as the increase overlying load and tends to stable finally. (4) The settlements of bearing platform and soil among piles are even and small. There is almost no difference in the settlements in goafs and non-goaf regions, and almost no deformation occurred at the bottom of goaf roof . (5) Pile-plank has a good effect on reinforcement for goaf roadbed.

Usually, stress state of the soil is replaced by plane strain state when slope stability is analyzed, which leads to conservative results adopting triaxial tests. Based on fully considering the physical meanings and mechanisms of the intermediate principal stress, this paper proposes a modified relationship of intermediate principal stress in plane strain state when soil approaches ultimate strength making. Mises strength criterion identical to the circle internally tangent to M-C strength criterion, and we further derive the ratio of maximum principal stress to minor principal stress, which is a constant associated with internal frictional angle under plane strain state. The ratio has been proved by tests, which demonstrates the modified relationship of intermediate principal stress is reasonable. Based on the ratio and the modified relationship, the stress path under plane strain state is derived. Combined with Lade-Duncan strength criterion, the strength formula transformation between plane strain state and triaxial state is established. Then, comparisons between internal frictional angle derived from plane strain experiment and strength formula transformation show that the errors between the two frictional angle are only about 2%, which largely decrease the errors caused by triaxial test. Two different strength parameters, one of which is derived from triaxial test and another of which is derived from strength formula transformation, are used to evaluate the stability of a homogeneous slope. The results show that, when the internal friction angle in triaxial test state is between 10°-20°, the difference of safety factor based on the two different strength parameters is small; if it beyond 20°, the safety factor in plane strain state is about 19% larger than that under triaxial state. However, the results are only effective in this study, a further study is needed. Furthermore, the critical slip surface depth becomes shallower and shape becomes steeper with larger strength of soil under plane strain state.

Taking the marble as the specimens, conventional triaxial compression tests under 20 MPa confining pressure and different axial compressions are first conducted. Then the nuclear magnetic resonance (NMR) tests are conducted on the loaded specimens. The stress-strain curves, crosswise relaxation time T2 distribution and rock porosity are obtained. The function about damage degree and porosity is established. The results show that: (1) The fitted function about porosity and axial compression ratio indicates that porosity of marble increases exponentially with the increase of axial compression. When the axial compression ratio is below 70%, specimens perform elastic deformation and the increase of porosity is small. When the axial compression ratio is above 70% and below 90%, the specimens perform plastic deformation and the porosity of specimens increases significantly. When the axial compression ratio is above 90%, the dilatancy of specimens increases sharply and the porosity of specimens multiplies. (2) The number and size of microcracks in specimens increase with the increase of axial compression. (3) The function about damage degree and axial compression ratio indicates that as the axial compression ratio increases, the damage degree of marble grows, and the effective stress of external loads also grows.

Researchers used high-pressure consolidation tests to study the deformation law of calcareous clast of coral reef during consolidation and rebound stages, as well as particle breaking conditions under diverse loading ways or saturated conditions. The results show that different contents of sand and gravel in sample play different roles during consolidation, which lead to different deformation laws. Loading method and aquiferous condition show appreciable impact too. Analysis of particle breakage result shows that 0.25mm is the relatively stable particle size during breaking, which is an important particle bound in particle breakage study. This finding is of great significance on using calcareous clast of coral reef as a stable packing material and increasing the stability of it.

Dilatancy is a basic behavior of soils which is closely related to strength and deformation behaviors of soils and makes soils significantly different from normal elastic materials. Four groups of large-scale triaxial tests were conducted to investigate the influence of dilatancy on strength and deformation behaviors of coarse-grained soils at different initial densities. The test results show that: (1) The stress-strain curve shows softening behavior if volumetric strain rate (the ratio of volumetric strain increment to axial strain increment, assume positive for volumetric strain and axial strain under compressed condition) firstly decreases from a positive value to a negative value and then increases but still smaller than zero; the dilatancy and strength of the soil reach maximum at the minimum value of the ratio, otherwise the stress-strain curve behaves as hardening behavior if the ratio of volumetric strain increment to axial strain increment decreases monotonously from a positive value but always larger than zero. (2) The variation trend of volumetric strain depends on dilatancy and compressibility of soils; the volumetric strain is firstly compressive and then dilatant and stress-strain curve behaves as stress softening form if dilatancy rate (the negative of the ratio of volumetric strain increment caused by shear stress to axial strain increment) is larger than compression rate (the ratio of volumetric strain increment caused by compression stress to axial strain increment) in the late shear stage; otherwise the volumetric strain is always compressive and the stress-strain curve behaves as hardening behavior for the condition that dilatancy rate is smaller than compression rate in the whole shear stage. It is of great importance to know the dilatancy of coarse-grained soils for insight into the strength and deformation behaviors of coarse-grained soils.

The composite bolt containing steel bar is applied successfully to the anchorage of earthen sites. However, its anchoring mechanism is only initially studied. In the Jiaohe ruins, a typical earthen site, the composite anchor containing steel bar (? 22 mm) were chosen to carry out the pull-out experiment as well as the interface strain monitoring among the bolt. The experimental results indicate that the maximum anchoring force of the 3 m-length bolt is over 190 kN; and the bolt shows the strong plastic deformation. The interface strain monitoring result reveals that as the damage interface the axial strain of the interface between steel and composite material is greater than the other ones. Due to the heterogeneity of the bolt, the irregularity of the axial strain occurs in the interface between bamboo and composite materials, which results in some local compression phenomenon. Meanwhile, the change of shear strain along bamboo-grout interface coincides with that of the pull-out load; and shear strain is transferred to the end of the bolt under larger load. Furthermore, because of the multilayer structure of the bolt, the transverse transfer and shearing expansion distinctly appear during pull-out experiment. The research lays the foundation to optimize the bolt structure and its anchoring craft.

Based on the uniform design, the influence of pile cap, cushion, pile spacing and pile length on bearing capacity of settlement reducing pile foundation has been researched through six lab model tests with 3×4 pile group. Earth pressure, axial force of pile shaft, and tunnel settlement are measured under the different load of immersed tunnel. Owing to the application of the uniform design, the test data can be analyzed with the mathematical statistics methods such as correlation and regression analysis, and the significant degree and influence effect of the four influence factors on the settlement are estimated. Different from the traditional single factor optimization, this approach makes it possible to study the comprehensive influence of the pile foundation on the tunnel settlement under the multi-factor and multi-level conditions. The result shows that the influence of pile length, pile spacing and pile cap on tunnel settlement varies with the increase of the external load, and that the cushion and the pile cap interacts with each other, having a joint effect on the tunnel settlement. Finally, with the back analysis based on the fitting results, one optimum combination is obtained among 432 combination forms and verified in the successive test, which provides a new effective and practical way for the optimum design.

For a large area of shallow slope covered with weathered soils, when the groundwater table or the impermeable bedrock is shallow, intense rainfall will result in the air in soils being closed. With the wetting front moving downward, air pressure increases constantly. Closed air pressure not only reduces rainwater infiltration rate of the soil in slope, but also has a significant effect on slope stability. This paper analyzed the formation of air pressure and its related theories, and suggested that a pressure head was used to study slope stability(Hc is a value of water head related to the pore size distribution; hd is an air-closing water head). Combining the Mohr-Coulomb failure criterion of unsaturated soil and the limit-equilibrium method, the closed air pressure head is applied to slope stability analysis; and the stability analysis model is established considering air pressure. The comparison was also carried out with the classical stability analysis method; and a concept of effect rate of air pressure is also defined. It is found that closed air pressure significantly reduce the safety factor of slope stability; the classical stability analysis method of infinite slope is more dangerous; research results in this study of infinite slope safety prediction have a great guide significance.

In order to provide the basement of a further numerical analysis, a series of large-scale triaxial creep tests is performed on gravel-soil obtained from sliding mass of Majiagou landslide in the Three Gorges area. The test results show that the tested gravel-soil is a typical creep material, and its creep deformation characteristics are very obvious. The soil experienced two creep stages, i.e., the decay creep stage and constant speed creep stage. The data also indicate that confining stress and stress level have an effect on the creep characteristics of soil. Based on these tests, the Singh-Mitchell model is used to predict the creep strain. Compared with the original test data, the Singh-Mitchell model results have good agreement with the experimental data.

A cumulative deformation forecast model can predict long-term settlement of sand under the train-induced vibration load and has a great practical value in engineering practice. Based on cyclic triaxial experiment on the remolded samples of Nanjing fine sand using GDS (geotechnical digital systems) dynamic hollow cylinder torsional apparatus, the article analyzes sand characteristics of accumuted deformation, summarizes current studies on a cumulative deformation model formula at home and abroad, and compares the different formulae results with the experiment data; finally finds the most suitable model formula for Nanjing fine sand. Through comparison and analysis, the formula of logarithm model, of which the parameters are determined, has been found having a good application effect on a cumulated deformation prediction of Nanjing fine sand.

In order to study the effect of temperature and confining pressure on rock mechanical properties and failure mode, experiments on granite under triaxial compression of different confining pressure from 0 to 40 MPa were conducted after high temperature of 25-1 000 ℃ by the MTS815.02 servo-controlled testing machine. The results show that: (1) Complete stress-strain curves of granite which heated to various temperatures under conventional triaxial compression with fixed confining pressure have experienced compaction, elasticity, yield, failure and plastic flow five stages. (2) Relationship between triaxial compressive strength of granite and confining pressure after high temperatures is nonlinear quadratic polynomial relations. When the confining pressure is 40 MPa, the triaxial compressive strength is increased 382.30% than uniaxial compressive strength; 400 ℃ is the threshold temperature of granite mechanical parameters under conventional triaxial compression conditions. (3) Elastic modulus of granite tends to increase with the confining pressure and quadratic nonlinearly decrease with the temperature, which is increased 90.26% than that at uniaxial compression when the confining pressure is 40 MPa, and when the temperature is 1 000 ℃, it is decreased 57.16% than that at 25 ℃. (4) Form of deformation and failure of rock samples is from brittle fracture transiting to plastic deformation as the temperature increases under uniaxial compression state. Instability mode is sudden instability at low temperatures, quasi- abrupt instability at medium-high temperature, and progressive failure at temperature higher than 800 ℃. Rupture type of rock samples changes from brittle tensile fracture to shear fracture gradually with the increase of confining pressure under triaxial compression. Instability mode of rock is dominated by sudden instability. In the experimental temperature and pressure range, temperature is the primary factor affecting mechanical properties of rock samples, followed by confining pressure, while the instability mode of granite depends on both confining pressure and temperature.

Compression index obtained from the oedometer test is required for calculation of ground settlements. However, oedometer test is very time consuming and expensive, and requires a lot of experience for obtaining undisturbed soil samples from the field. Equation needs to be developed in order to predict compression index using index properties of soil which are relatively easier to obtain. Intact samples are taken in Shanghai area using thin-wall samplers, and are conducted by oedometer tests. The data used for the study consist of current and existing laboratory results from several geotechnical investigation reports. Natural water content has good linear correlation with initial void ratio, but not obvious with liquid limit. Since water content is more easier to obtain than initial void ratio, it is used to predict compression index. Commonly used linear equation is not suitable for Shanghai clay, especially when water content is higher than 45%. Finally, an exponential function involving the water content is recommended to predict compression index of upper Shanghai clay for preliminary engineering design. The function is also verified by compression index of clays at other places in coastal area of eastern China.

In light of the inapplicability of common method to get p-y curves near a slope, a series of model tests on lateral static loading is carried out for single flexible piles near a slope. There are totally 11 series tests of different slope angle and distance between slope and pile. The strain curves of pile are fitted with piecewise cubic polynomial, which avoids singular points effectively. p curves and y curves are gained through derivation and integration of strain curves. The load-displacement curves are drawed, and the influence of slope on the distribution of bending moment is analyzed. Existing expression is introduced and revised according to test results to get the ultimate lateral resistance near a slope. Other reseracher’s expression is employed to get the initial stiffness of p-y curves near a slope. The final expression of p-y curves put forward in this paper is approved reasonable by comparison with a typical centrifuge test results.

In order to reinforce the loose, high moisture and unstable strata in the underground engineering artificial freezing method was commonly used, and vertical straight layout of the frozen pipes was used frequently. However, the distribution and changes of temperature, stress and displacement were completely different from vertical circular layout, thereby induced engineering stability problems were paid less attention, which need further investigation both at home and abroad. On the basis of an inclined shaft freezing construction, the similarity criteria in the vertical straight freezing process were derived, which contained temperature field, stress field and moisture field, etc. Specific experiment program during the total process of soil freezing was designed detailedly. In self-made three-dimensional simulation freezing experiment system, 20 vertical frozen pipes were layout as 4×5 form. Stress environment and seepage condition were simulated as possible as field conditions. The value and change rate of soil temperature and horizontal frost heaving force were measured during the process of soil freezing. On this basis, the distribution of soil temperature and horizontal frost heaving force in different depth were investigated. Experiment results show that in vertical straight freezing, the impact of soil depth on the horizontal frost heaving force is significantly. In the same depth and ignoring the impact of other conditions, the value of frost heaving force and soil temperature are closely related; the change rate of frost heaving force mainly depends on the location of freezing front, which reaches its peak gradually by the distance close to freezing front; while the horizontal frost heaving force in frozen soil has stabilized with the development of freezing front.

To evaluate the changing degree of single pile vertical bearing behavior resulted by defect piles such as stem shrinkage pile, stem enlargement pile and broken pile which are developed in construction process, field model tests were used to analyze single defect piles. And measurements of its ultimate bearing behavior were carried out by conducting vertical static loaded tests of test piles with and without defects. Compared with normal piles, the influences of defects mentioned above on bearing behavior of piles were studied. Conclusions are drawn based on the designing scheme of test piles in the paper through comparative analyses of the load-settlement curves of normal piles and defect piles. Compared with the vertical ultimate load capacity of single normal pile, it reduces by less than 15 percent due to defects in single pile such as stem shrinkage pile or a pile with mud cake around. The steep drop point is not so clear in the load-settlement curve of single stem shrinkage pile, the top settlement of which increases more gradually than normal pile. The occurrence of inflection point in load-settlement curves of broken piles is determined by the distance of broken defect from ground surface.

The shear failure characteristics and failure law of spread foundations are researched by tests on ten model foundations. The results show that punching shear failure of foundations will occur when the width of foundation is greater than the width of column plus double effective height h0 of the foundation. When the width of foundation is less or equal to the width of column plus double h0, shear failure will occur if only arranging bending reinforcement; and bending failure will occur if arranging reinforcement according to beam. The ductility and bearing capacity of strip footing under column will increase considerably comparing with raft foundations when the size of foundation and longitudinal reinforcements are identical. The arrangement of reinforcement of strip footing under column should design according to that of beams are suggested, so as to avoid brittle shear failure of foundations.

Based on the curtain grouting engineering of Zhongjiashan tunnel, a large-scale model test device is designed to simulate the process of fracture grouting in fault fracture zone. The variation law of key parameters during the grouting are recorded and analyzed by layouting monitoring components, and the distribution of grouting veins are exposed intuitively by excavating the filling medium. The test results show that the fracturing pressure presents a pulse-like law during the grouting process, and the first fracturing pressure under the conditions of this test is 0.12 MPa which is made a comparative analysis with the existing theoretical solution. The change mechanism of fracturing pressure is analyzed based on the conversion of slurry diffusion form, saturation of primary and secondary fracturing channels, formation of new fracturing channels and saturation of the follow-up fracturing zone. The definition methods of primary and secondary fracturing pressure are proposed; then 7 primary fracturing pressure and 53 secondary fracturing pressure under the conditions of this test are found to show an increasing law approximately. Based on the p-t curve, the fracturing process of soil are divided into 3 stages including the energy accumulation, soil fracturing and slurry energy transfer from the perspective of energy dissipation. The spatial distribution law and coexistence law of primary and secondary grouting veins are found by excavating the filling medium. The site application test is carried out in curtain grouting engineering of Zhongjiashan tunnel to verify the correctness of test results. The test results play a guiding role on the understanding of grouting theory and the application of grouting engineering to some extent.

At present, studies of pile-supported embankment focus mainly on the stress ratio of pile to soil and the soil arch effect under static loading, less considering effects of dynamic loading. But dynamic stress resulting from vehicle operation has a certain influence on the embankment of soil arch, which affects the overall behavior of pile-supported embankment. In order to analyze the change of bearing behavior of pile-supported embankment under static and dynamic loading, through visible laboratory test and analysis of particle flow code(PFC), the mechanism of stress transfer and deformation of pile-supported embankment under static and dynamic loading have been studied. Some factors affecting soil arching are investigated, such as filling height, pile cap size, pile spacing, reinforcing modes, loading frequency. The results show that the stress on top of piles decreases under dynamic loading, which resulted in increase of stress between piles and displacement of embankment. The effect of dynamic loading on unreinforced embankment is larger than that on reinforced embankment. And reinforcement material is helpful to reduce the impact of dynamic loading. The mechanisms of load transfer and deformation are different depending on the types and numbers of the geogrid; and the impact of dynamic loading is mainly related to the strength of the soil arch effect. In the case of piled embankment reinforced by two layer geogrids, because the mechanism of semi-rigid platform takes effect due to the interaction of reinforcement and the surrounding fill, the soil arching decreases which leads to the effect of dynamic loading minimally; and for embankment with a single geogrid, the impact by dynamic loading decreases remarkably when geogrid is set above 10 cm of top of piles compared with geogrid on the top of piles. The PFC simulation results confirm the above conclusion, and further conclud that with the increase of loading frequency and the filling soil height, the decrease of pile net spacing, the effect of dynamic loading increases.

The surrounding rock quality and construction method are essential reasons affecting overbreak-underbreak of tunnels. It is important to evaluate and forecast overbreak-underbreak, and judge the stability of tunnel structure for researching the relation between surrounding rock quality and overbreak-underbreak. Based on the measured data and numerical experiment, the effect of span on surrounding rock quality is studied; and modified rock quality index based on multifactor evaluation is established. According to excavation section profile showing the fractal characteristics, the fractal dimensions of 20 sections profile of Yuanyanghui tunnel are calculated; and the relation between surrounding rock quality and overbreak-underbreak is studied. The linear relations among modified rock quality index and percent of overbreak and fractal dimension are gained. With the increase of modified rock quality index, the percent of overbreak and fractal dimension are decreased. According to the principle of multiple correlation, the multiple correlation among modified rock quality index and percent of overbreak and fractal dimension of section profile are established so as to provide reference for correct evaluation of surrounding rock quality and analysis of overbreak-underbreak. Meanwhile, by contrast with relation between different surrounding rock classifications and overbreak-underbreak, it is shown that BQ method based on multifactor evaluation has better adaptability in tunneling engineering.

The excavation area of Shanghai International Financial Center, whose surrounding environment is complex, is 48 860 m2. The depth of the excavation ranges from 26.5 to 27.9 m. In order to minimize pumping effects of confined water on the surrounding environment, a 700 mm thick and 56 m deep constant thickness cement-soil wall has constructed as a watertight screen along the periphery of the excavation. As the first time to construct such a deep TRD wall in Shanghai, a series of tests had carried out on the site. The monitoring results show that the strength of the cement-soil wall has ranged from 0.84 MPa to 1.38 MPa in the deep aquifer. Laboratory permeability test results show that the permeability of the wall is increased from 10-3 cm/s to 10-7 cm/s. Both strength and permeability of the wall satisfied the design requirements for a watertight screen. During construction of the wall, the maximum surface settlement is about 8 mm and the main influence zone is approximately 5m away from the wall. It is also observed that lateral soil displacements mainly took place within 5 m from the wall. Therefore, the influence of the wall construction on the surrounding environment is negligible. The test results provide references for subsequent construction of the TRD walls and serve as a case study for similar projects in Shanghai as well.

The project of wind power generation is an important step of the sustainable development path of China or even the world. Piled beam-slab foundation of wind generating set is a new form of the foundation for wind turbine on land, the research on which is attracting broad attention in academic and engineering fields. Through installing earth pressure cells under the baseboard and reinforcement meters in the piles, the test, based on the wind turbine project at Sheyang port in Jiangsu province, measures the soil pressure under the foundation and the axial force at the top of piles when the wind turbine is under construction and working normally. The research mainly focuses on the change rules of the axial force at the top of piles of the wind turbine piled beam-slab foundation under construction condition and working condition and the analysis of the load sharing percent of piles and soil. The contrastive analysis of the internal forces between the field test and actual design calculation is also carried out. The results show that the piles bear most of the load before the wind turbine running; piles inside bear less load and piles outside bear more after the wind turbine running. The soil bears large percentage of load when the wind turbine is working; so the current design method which doesn’t consider the bearing capacity of soil makes the result safer.

This paper presents an investigation into crack evolution in rocks containing pre-existing double flaw by distinct element method. Based on experimental data, a zero-thickness microscopic bond contact model containing rolling resistance is proposed and implemented into distinct element method commercial software. Crack propagation and coalescence in double-flawed rock samples under uniaxial compressive conditions are modeled. The mechanisms of crack propagation and coalescence are illustrated from the macroscopic and microscopic viewpoints. Simultaneously, the crack propagation and coalescence as well as strength properties measured in the Discrete Element Method (DEM) simulations are compared with the experimental observations. The results demonstrate that tensile stress concentrations between the pre-existing flaws and in their endpoints cause the instability and failure of rock samples containing pre-existing double flaw. The crack evolutions obtained from experiments and our DEM simulations are in good agreement. Rock samples containing flaw of an inclined ? =30°to the horizontal is most easily to initiate, while rock samples containing flaw of an inclined ? =75°to the horizontal is most difficult to initiate.

Six typical shapes of rockfill were selected and simulated by clusters of round particles. Two kinds of contact constitutive models were adopted to establish multi-shape numerical model of rockfill. The process of particles crushing under vibration compaction was simulated and the mechanism of crushing was discussed. A quantitative calculation method of crushing was proposed, which can be used to analyze the variation of grain size distribution curve before and after particle crushing. The effect of different contact constitutive models on the numerical results was also discussed in detail. The numerical results indicate that the tensile cracking is dominated and the shear failure zone appears only after several numbers of vibration rolling compaction. Although the crushing ratio calculated from the proposed quantitative calculation method results is higher than the test data for the large particles; the grain size distribution curve predicted from the numerical method has a good agreement with the test results on the whole. The predicted results from the numerical models of parallel-bounded law are more rational than that from the contact bounded model. The numerical results from the 6 shapes models indicate that the crushing ratio decreases with the increasing of shape coefficients. The rectangular particles are more fragile than other shapes. These study results of different particle shapes indicate the numerical model consists of 6 different shapes are more rational than pure round particles or single non-round particles.

Considering the yield characters of foundation soil, the soil surrounding pile shaft is divided into elastic and plastic deformation zones. Based on the beam-on-foundation method the deflection curves differential equations of elastic and plastic zones of pile shaft are established respectively assuming that the coefficient of subgrade reaction is the three-parametric general form and the effect and effects such as gravity of pile, skin friction of pile are all taken into account. During the process of solving the differential equations, matrix transfer method with Laplace forward transformation and Laplace inverse transformation has been used to solve the deformation and internal force for axially and laterally loaded piles. And then, the computational procedure is compiled using the Fortran language. Finally, this approach is verified by the data from experiment. The results indicate that the computed data and test data are in good agreement; and then, the discreteness of inversion parameters of three-parametric subgrade reaction is very small, meaning that the presented approach is applicable in engineering practice.

As a new bridge type, integral bridge can significantly reduce the long term maintenance cost, and its application should be encouraged in China. However, there is great uncertainty about the dynamic performance of integral abutments during earthquake. This paper presents the findings from a dynamic numerical simulation about a typical integral bridge. The influence of seismic peak acceleration, abutment height, and bridge deck length has been investigated. The effects of two mitigation methods, e.g. installation of a flexible layer and reinforced soil behind the abutment, have also been discussed. The results show that the traditional M-O method adopted in the current bridge abutment design code cannot give a reasonable prediction about the dynamic earth pressure behind integral abutment, which would lead to an unsafe design. Although a flexible layer can reduce the earth pressure, the deformation and bending moments will increase. Reinforcement can provide horizontal tensile forces to the abutment, leading to reduce abutment deformation and bending moments.

By adopting Biot’s consolidation theory and the contact analysis of discontinuity surfaces, a two-dimensional calculation model containing two ground fissures is set up based on detailed groundwater and stratigraphic data in Xi’an. By using this model, the pumping-induced land subsidence under preexisting fault situation is simulated as much detailed as possible. Combining the land subsidence monitoring, the space distribution pattern is analyzed. The results indicate that the amount of compression of the soil deposit 100-300 m beneath contributes to the main settlement. The initiation of the ground fissures is not only for the differential subsidence caused by thickness change of soil deposit, but also the presence of fault. Because of the existing of the normal fault, the displacement of hanging wall is magnified, while the displacement is reduced during the ground subsidence. The reverse effect makes the scarp become larger and larger; so that the ground fissure hazards become more and more serious. The research results are benefit to further understanding the mechanisms of ground fissures, also can play some roles for predicting its development.

The fault structure is the key factor constraining the design and construction of underground works. A unified model of the strata, faults, and underground caverns were established within a method of 3D geological modeling considering the coupling relationship of complex geological structures and underground cavern group. A concept of fault staggered and topological complexity is put forward based on the unified 3D model. And a new analysis method is provided to solve the location problem of underground caverns in the design of the hydropower engineering. In light of surrounding rock stability, an identification method of curved surface blocks based on the staggered cut of faults and the excavation faces is proposed to search the instability regions in the underground cavern group. This method has successfully applied to a hydropower engineering with underground cavern group and played an important role in program optimization and rock stability analysis.

In order to represent and disseminate geological boreholes on digital earth platforms, we present an automatic method for the modeling and visualization of boreholes in urban areas. At first, several borehole models with different levels of detail, such as point placemarks, scatter dots and tube models, are created according to a standard form of borehole database. And then, a LOD-based multi-scale representation is constructed to visualize massive boreholes. Finally, borehole models are loaded into a digital earth platform for 3D visualization and spatial analysis. A concrete example of applying this method to create borehole models in Shanghai shows that the modeling process is simple, automatic and effective. In addition, borehole models generated from this method are well-suited to the dissemination, integration and visualization on the Internet. Therefore, the widespread future use of this method will help earth scientists share their borehole data more easily. This will make borehole information accessible to a broad user base, and may promote the development on the social service of geological information in urban areas.

Taking into account the uncertainties of the calculation model of bearing capacity and the load, with the reliability analysis method and the theory of probability and statistics, the calculation formulas of reliability indices for ultimate limit state (ULS) and serviceability limit state (SLS) are obtained respectively. Meanwhile, the linear relationship between reliability indices for ULS and SLS is presented. Finally, it is studied that the impact of stochastic behaviors of limiting tolerable settlement of pile head ( ) on reliability analysis for SLS. The following conclusions can be drawn from this study. First, the influences of soil type and pile type on the model factor for SLS are slight. Second, the reliability index for SLS decreases with an increase of the uncertainties from the bearing capacity calculation model and the load, although the decrease rate gradually diminishes. And the total variation in the reliability index for SLS is limited, which means that it is reasonable to ignore the influences of the uncertainties from the bearing capacity calculation model and the load on the reliability analysis for SLS in engineering practice. Third, the stochastic behaviors of have significant effect on reliability analysis for SLS. The model factor and reliability index for SLS both increase with an increase of . However, the variability of model factor for SLS decreases with increase of . The appearance of these conclusions is simply because the requirements of are different, but is not the result that the pile own properties have run into some changes. The research results would provide a reference for code amendment and engineering applications.

In response to the problem of more influence factors and difficulties in identifying the depth of damage floor of coal seam, six factors including mining depth, mining height, incline section length (working face), dip angle, floor lithological combination and roof lithological combination were selected to research the depth of damage floor by analyzing two aspects influential elements of the deformation degree of the floor rock, geological model was generalized and six factors and five levels orthogonal numerical simulation experiment were carried out with mine 4602 working face as the background. The experimental results showed that: (1) The main factors influencing the depth of damage floor were incline section length, floor lithological combination, roof lithological combination, mining depth and mining height were weakened in order, dip angle was weakest; (2) that roof lithological combination was the key factors in influencing the floor damage depth was made clear for the first time; (3) prediction model of mining depth of damage floor on incline section length - floor and roof lithological combination - mining depth - mining height - dip angle was established, the calculation results were more close to reality comparing with the results of mining regulation empirical formula calculation, and the precision was high, the error was low, and it can meet the engineering use basically. The results of the study had a positive guiding significance on the research of the depth of damage floor and engineering application.

Several strong earthquakes proved that the concrete face rockfill dam (CFRD) has nicer aseismic behavior; but its dynamic response is still concerned, especially when the dam height comes in the level of 300 m and it is built on complicated valley terrain conditions, etc. Analyzes the dynamic response of CFRD under complicated topographic condition (the shape of valley is irregular W) by using the equivalent viscoelastic model. It is concluded that the dynamic response of CFRD under complicated topographic condition is more complex than under a single topographic condition, but the rules are same. The strongest dynamic response acceleration locates on dam’s crest of the largest section, the biggest earthquake’s settlement is about 0.30% of the dam height. Because of the ancient river terraces on the right bank and vertical slope on the left bank, axial and consequent dynamic acceleration magnification on the right bank are greater than on the left bank; but the vertical dynamic acceleration magnification is contrary. There is an obvious displacement area near the ancient river terraces. Under the influence of seism and terrain conditions, the larger net tensile stress appears on the upper panel to the left bank, which may lead to panel cracking damage. According to the results, the failure forms of high CFRD mainly include the downstream dam slope instability, panel cracking and excessive settlement. Finally, some viable aseismic measures are discussed.

In light of the problem that the related triaxial stress seepage experiment devices lack of high pressure water and negative pressure loading function at present, the gas seepage law of coal samples cannot be studied under both of these cases. A kind of new triaxial stress seepage experiment device has been developed, of which the export negative pressure of coal sample itself is adjustable and the high pressure water can be loaded to the coal sample. The device is mainly composed of five parts including triaxial stress loading system, gas seepage system, hydraulic fracturing control system, gas flow test system, sensing and control system, all sorts of uniaxial and triaxial seepage experiments can be carried out in the case that samples are loaded by high pressure water or the negative pressure. Studies have shown that the device can simulate the gas migration law about coal body when the pressure of extraction drill hole is negative and can investigate the hydraulic fracturing effect of coal, complete the research about gas seepage law of coal sample under negative pressure condition, at the same time accomplish the inspection about the anti-reflection effect of coal body after hydraulic fracturing measures implemented in the laboratory.