In light of the limitation of analyzing the single spalling rock plate by the existing catastrophe theory, studying the spalling rock plates as a whole is put forward; the catastrophe theory applied to the rockburst analysis is improved, considering the horizontal stress between the splitting rock plates. Based on this, the rockburst proneness of single rock plate and combined spalling rock plates are calculated and compared respectively under the conditions of quasi-static and dynamic disturbance. The results show that: under the condition of quasi-static, the eigenvalue Δ of single rock plate changes gently while the eigenvalue Δ of combined spalling rock plates increases rapidly because of the large equivalent flexural rigidity; the rockburst depth of combined rock plates is obviously larger than that of single rock plate; and the depth reaches 0.76 m. As the thickness of rock plate increases, eigenvalue Δ grows up gradually and the sufficient condition of rockburst in no longer fulfilled. However, the catastrophe condition can be fulfilled again if external vertical disturbing stress is applied on the rock plates and the external stress needed increases from several MPa to tens of MPa.

The base reaction and deformation features are analyzed based on measured data, according to model test of variable-length CFG pile composite foundation for frame-tube structure. Some conclusions are drawn as follows. First, under the working loads, longitudinal deflection of medial axis of foundation is 0.25‰, and longitudinal deflection of diagonal direction of foundation is 0.21‰, as adopting long piles to strengthen the area of core-tube, short piles to weaken the area of outside frame column, and middle length piles between area of core-tube and area of outside frame column to transit. Second, under the working loads, the pile top stress of core-tube is obviously higher than pile top stress of outside frame column. Pile top stress of core-tube area is relatively uniformly. The biggest pile top stress is on the corner pile, next is on the side pile, and the smallest is on the center pile in the area of core-tube. Soil stress between area of core-tube and area of outside frame column is little difference. The distribution of soil stress is even distribution both in area of core-tube and outside frame column, and bearing capacity of soil among piles of three areas all can play fully. Third, under the working loads, the highest stress of the base force is in area of the core-tube, distributes relatively uniformly and shows linear distribution basically. Base reaction is gradually weak from area of core-tube to area of outside frame column. The lowest stress of the base force is in area of outside frame column, its distribution is relatively uniformly and basically line-shaped. The base reaction basically shows basin-shaped. Distribution of base reaction is obviously related with composite modulus, which is basically linear relationship.

The retical formula of diffusion parameters of Newtonian fluid based on column–hemispherical penetration grouting is not existence, such as, diffusion radius of hemispheroid, diffusion length belongs to cylinder etc; so it lag far behind the actual grouting engineering. In this study, according to combining with the rheological equation and seepage motion equation of Newtonian fluid, theory formula of diffusion radius of hemispheroid, diffusion length belongs to cylinder based on column–hemispherical penetration grouting were deduced. Relationships between some grouting factors and them based on cylindrical penetration grouting, such as, rheology of Newtonian fluid, grout pressure, groundwater pressure and water temperature of configuration cement, were analyzed theoretically. What’s more, they were validated by means of designing grouting verifying experiments. Experimental results show the theoretical diffusion radius of hemispheroid, diffusion length belongs to cylinder calculated by the formula of diffusion parameters of Newtonian fluid based on column-hemispherical penetration grouting have about 30% of the differences with the actual measurement diffusion radius by grouting experiments; but they are all within the acceptable error limits. Therefore, research achievements may not only provide strong theoretical basis for perfecting the penetration grouting mechanism, but also play a reference guiding role for the theoretical research, design and construction on grouting technique.

For the thick fill foundation, due to its effects of consolidation on piles, deformation, the pile negative side fricition can not be ignored. Based on the monitoring data of the actual project site, the distribution law of the negative side of pile friction in thick fill site is analyzed; and a simplified theory calculated figure of negative side friction linear distribution along the axial, and the negative side friction coefficient calculation method are proposed. Through the comparison and analysis of the monitoring data, the negative side friction coefficient in thick fill foundation is obtained about 0.09-0.15, which verifies the rationality of the method proposed for the rational design of similar site pile foundations.

The plane shape, size of the excavation and embedment depth of the retaining wall all affect the heave-resistant stability of excavations. However, the influence of above factors can’t be comprehensively expressed by the calculation methods of safety coefficient of heave-resistant stability recommended from existing standards and codes. In order to solve this problem and differentiate the situations, the possible failure modes of basal heave are classified; and thereby the corresponding formulas calculating the safety coefficient of heave-resistant stability under different failure modes are given. Based on this method, the heave-resistant stability of excavations will be influenced by the strength, stiffness and embedment depth of the retaining wall. The calculation analyses indicate that, for both the drained and undrained situation, the narrow excavations are more stable than wide ones, and that the stability can be improved by adjusting the embedment depth of the retaining wall. The improved excavation safety factor, can take more factors into account, which provides a theoretical method to reduce the embedded depths of the retaining wall of narrow excavations.

The high loess-filled project research is a new research topic in the field of geotechnical engineering with impressive prospects. In this paper, indoor compression consolidation and moistening tests are carried out for high loess-filled project researches in Yan’an new district; the influence factors of deformation characteristics of compacted loess are analyzed; the best fitting model of vertical pressure and strain of compacted loess is built; and also, the consolidation and moistening settlements of the 100 m high project are predicted under different compactnesses. The results show that: (1) The vertical pressure-strain curves of compacted loess can be expressed with Gunary model. (2) The lower compactness of compacted loess will produce collapsibility deformation under lower pressure, higher pressure does not; the moderate compactness does not produce collapsible deformation under lower pressure, but higher pressure does; with the continued increase of compactness, the compacted loess does not produce collapsibility deformation under both lower and higher pressure. (3) Under the condition of optimum water content, the settlements of the 100 m high project are predicted under different compactnesses, so as to guide the field compaction and test the quality of construction. (4) The higher the compactness of compacted loess is, the smaller the total amount of deformation is, the greater the amount of water moistening deformation ratio of the total amount of deformation is, the lesser the consolidation compression deformation ratio of the total amount of deformation is.

Due to reasons such as the reservoir water level fluctuation and rainfall preliminarily, alternate wetting and drying usually occurred in the rock, which is fairly harmful for long term safety of rock. Taking argillaceous sandstone in Three Gorges Reservoir area as the research object, the conventional uniaxial and triaxial compression tests after the action of wet and dry cycle in acid environment, have been conducted to obtain the relevant mechanical parameters of the argillaceous sandstone in wet and dry cycle of acid environment. Relative to the dry specimen without dry-wet cycle, there are different degrees of reduction in elastic modulus , uniaxial compressive strength ,cohesion and internal friction angle of argillaceous sandstone with different times of dry-wet cycle. Overall trends of substantial decrease of various mechanical in dices appears, at which saturated with water for the first time, then the decrease of amplitude reduces with the increase in wet and dry cycles. Meanwhile, the pH value of acid environment has a great influence on the mechanical properties; there is a critical pH value influencing the mechanical properties of argillaceous sandstone. The influence of acid environment on mechanical properties of argillaceous sandstone significantly increase in the case below this critical value, there is smaller influence on its mechanical properties when the pH value is higher than the critical pH value.

The creep of soil is affected by many factors , behaving variable under different conditions. Tianjin Binhai dredger fill also has soft soil creep characteristics possessed by the general. Unconsolidated and non-drained triaxial tests and uniaxial compression creep tests were carried out with the soil triaxial rheological testing machine to study the creep characteristics of soft dredger fill, 10 time node samplings during creep have been selected for miniature vane shear test to study the variation of long-term strength. The results showed that: uniaxial compression creep and triaxial creep duration curve has a nonlinear characteristic, the isochronous curves deviated to the stress axis with the improvement of stress in uniaxial compression creep, while the isochronous curves deviated to the strain axis in triaxial creep. Viscosity coefficient is merely relative with the time under the linear condition, while associating with time and stress level on the nonlinear condition. In the three axis creep condition，the compression modulus decreases with the time increasing, the long-term strength firstly decreases and then tends to be stable over time. The uniaxial compression modulus increases with time increasing, Therefore the functional relations of the long-term strength are derived with time and deviatoric stress under different states of stress.

In order to determine nonlinear constitutive model parameters of rockfill materials, the inversion procedure based on response surface method is proposed. The sequential impoundment processes of concrete-faced rockfill dam are simulated by using nonlinear finite element method. The response surface functions of forecasting dam settlement for every observing point are presented. The coefficients of response surface function are calculated. Model parameters of nonlinear constitutive relationship of rockfill materials are determined using observed deformations after dam construction and response surface functions of forecasting dam settlement. The practical applications show that the proposed inversion procedure is of higher computing efficiency; and the forecasted dam settlements agree well with observed values.

Taking into account the displacement non-compatibility between the deep mixing columns and the surrounding soils, a new method is developed for calculating the total settlement of ground improved by deep mixing column method. Based on previous test results, a simplified column-soil stress ratio and differential settlement between column and surrounding soil calculation model was proposed. Column lateral friction and loading sharing ratio between columns and soils were calculated based on the actual stress state; and then the settlements of column and surrounding soil were calculated respectively. The new method satisfied force equilibrium and displacement compatibility of the system components, including the embankment, column, and foundation soil between and under columns. In order to verify the correctness of the proposed model, the measured settlement in Huai-Yan expressway, the settlements calculated by the proposed method and traditional composite modulus method were compared. Results indicate that the settlement calculated by the proposed method is in good agreement with the measured result; and the proposed method precedes the traditional composite modulus method.

Experiments were conducted in a large-scale direct shear apparatus to study the mechanical behavior at the sand-geogrid (S-GG) and sand-geotextile (S-GT) interface. The results show that a certain relationship exists between peak/residual shear strength and shear dilatancy of interface. That is, peak shear stress will occur at a stage when relative shear compression finishes, while residual shear stress will occur when relative shear dilatancy finishes. The shear stress obvious reduction with increasing shear displacement is known to be caused by geosynthetics polishing, folding and rupture, which should not be neglected in interface behavior studying. Thus, a combined constitutive model has been presented for predicting sand-geogrid interface behavior. The model is composed of four relationships: (1) The peak/residual shear strength envelope. (2) A hyperbolic relationship model of shear behavior in pre-peak region. (3) A displacement-softening model for post-peak region. (4) Modeling for shear dilatancy of sand-geogrid interface. The predictions made by the proposed model are found to be in good agreement with the results of direct shear tests, so as to prove that the model is reasonable.

Shale gas, an important unconventional natural gas resources, is transforming world energy and economic and political pattern. Permeability is one of the most important parameters of shale gas reservoirs that estimates their viability for commercial development. The mechanism of gas flow in the shale gas reservoirs is different from that of a conventional gas reservoir because of the tight nature of the rock matrix. Therefore, permeability measurements of shale reservoirs and flow model for shale gas have become one of hot topics for international research in nowadays. In this paper, theoretical and experimental studies of permeability measurements of shale reservoirs are summarized based on a simple presentation of shale gas production technique. Furthermore, the effects of gas adsorption on shale permeability are analyzed. Latest advances of shale gas flow model are reviewed; and accuracy of a dual-pore model describing gas transport is analyzed. Multistage transport models for desorption and diffusion and seepage of shale gas are presented, which can be used to describe behavior of gas flow in the homogeneous reservoirs. Brief reviews on greenhouse effect of shale gas extraction and its impact on groundwater are also addressed; and then shale gas production technique for waterless hydraulic fracturing is presented. That is, shale gas reservoirs are fractured multistage via carbon dioxide injection, and meanwhile carbon dioxide is sequestrated in the abandoned shale gas wells. A few of comments are also made on the future research directions and subjects on permeability measurements of shale reservoirs and shale gas flow model and waterless hydraulic fracturing technology.

Jet grouting soil-cement-pile strengthened pile (JPP for short) is a new type pile which is composite of jet grouting pile and prestressed concrete core pile, and achieving the powerful effect of rigid pile and low cost of flexible pile. JPP pile is used in excavation protection and other engineering, but its research on horizontal bearing behavior falls behind the engineering practice. In order to study the horizontal bearing behaviors of different combinations JPP pile, horizontal load model tests are carried out by using the home-made model test pile loading system. The test results show that: sub-portfolio II carries maximum capacity, combined with the sub-portfolio I close, under combination carries the lowest capacity level, so the more sub-portfolio combination shows that the overall horizontal bearing capacity appears. Maximum moment of JPP pile occurs at the position of 3 to 4 times diameter under core pile top and this site is relatively weak and prone to damage. So we can conclude that the soil characteristics within a certain depth below the soil surface will have a direct impact on the horizontal bearing capacity.

As the result of the direct shear test and triaxial test, strength index of over-consolidated soil is not in conformity to that of normally consolidated soil. Shear strength index under the pressure which is greater or less than the previous consolidation pressure is obviously different; and the test data should be respectively processed. Prior to shearing, the sample pretreatment should be in the condition of dead weight stress or preconsolidation pressure. The comparison of the shear strength index under the vertical stress or confining pressure which is smaller than and greater than previous consolidation pressure shows: the former cohesion obtained by unconsolidated undrained shear test is smaller than the latter; on the contrary, the internal friction angle is larger; it is just the opposite in consolidated undrained shear test; the stress history simulated through experiment for remolded soil is difficult to reflect the actual strength characteristics, so test should be carried out by using undisturbed soil. Laboratory test should determine the previous consolidation pressure and K0; and then, according to the actual engineering stress state, the shear strength index can be obtained.

Different proportions of aggregate and adhesive materials of low strength similar material were developed by similar proportioning test, and the influences of sand-binder ratio and cement content of cemented material on similar material properties were analyzed. Then three feasible and effective proportions of similar materials were determined and a multilayer shale deposits model was established based on condition of deposit and experimental. The results show that the density, uniaxial compressive strength (UCS), elastic modulus, and Poisson's ratio increase with the cement content of cemented material increasing. And the density, porosity, elastic modulus, and Poisson's ratio are less volatility in low sand-binder ratio. Further studies prove that the error between actual similar constant and design similar constant of low strength similar material is less than 1.77%. Meanwhile, combining with the results of numerical simulation, the pillar strain variation between numerical simulation and similar simulation test is less than 8.76%, and the deformation characteristics agree well with each other. It indicats that test model is reasonable and effective in studying multilayer shale deposits model experiment. The study results provide an effective scientific basis and experimental basis of multilayer shale deposit underground mining research.

Based on the analytical stiffness matrix solution for layered soil, the calculated method for additional loads induced by the pipe bulkhead additional pressure, and the propulsion friction force between the shield and surrounding soil, and the interaction forces, is derived by means of five-node Gauss-Legendre integral arithmetic. The distribution rule for vertical additional loads induced by pipe jacking construction is analyzed. Furthermore, the influences of equivalent uniform characteristics, soil mechanical parameters, spacing distance for calculation point, and pipe buried depth on additional loads are discussed. The research results show that the peak compressive stress is rapidly achieved ahead by the shield opening according to the additional loads due to the friction force. The value and influence scope of propulsion effects due to the friction force is more obvious than that due to bulkhead additional pressure. The friction force is the main influence factor of additional loads induced by pipe jacking. In addition, the change of layered soil parameters will lead to a certain extent impact on additional loads. The equivalent uniform characteristics, spacing distance for calculation point, and pipe buried depth have distinct influences on the magnitude and distribution of additional loads. The results may provide certain basis to draw up correctly protective measurements of geotechnical environments influenced by pipe jacking construction. The research results can also provide theoretical references to the other projects such as metro tunnel engineering.

A method for predicting evaporation process in unsaturated soil surface is presented based on physical properties of soil and meteorological data. The soil-water characteristic curve (SWCC) is estimated by physical properties of soil (i.e. particle size distribution, specific gravity and dry density). Then, the relationship between relative humidity of soil surface and water content is obtained based on the SWCC. Finally, the Penman-Wilson model is applied to predict evaporation curve of unsaturated soil surface. In this method, only in situ soil physical properties and meteorological data are needed to get the predicted evaporation curve. The evaporation rate of soil surface can be obtained with given water content at that time. Laboratory evaporation tests of thin layer soils are conducted in a designed evaporation measuring system. The measured evaporation curves are compared with those predicted. The results show that the measured and prediction evaporation curves have same processes and slight difference in evaporation rate. Three evaporation stages, i.e. stable rate stage, reducing rate stage and residual stage, are evidently shown in both observed and predicted curves. The stages are divided by as called critical moisture content and air-dried moisture content. The suggested method is accurate and practical for engineers to predict unsaturated soil surface evaporation rate and determine the boundary flux.

Based on the analytical solution for soil nailing tension model and the field measured data of soil nailing tensile test，the influences of elastic modulus of cement grout Eg and shear deformation coefficient of soil nailing K on the mechanical properties of soil nailing are analyzed. The results show that the displacement of nail head under the maximum loading decreases as Eg increases. With the increase of Eg, the relative displacement and shear force between soil and nail, decrease in the shallow part of the nail body, and increase in its deep part, respectively. Furthermore, the variations of relative displacement and shear force between soil and nail along the nail body direction become much smaller with the increase of Eg, resulting in more homogeneous distribution of side friction resistance along the nail body. As K increases, the relative displacement between soil and nail under the maximum loading decreases and the variation of relative displacement along the nail body direction becomes much smaller, indicating the effect of grouting on soil nailing gradually becomes marginal. With the same change rate of K and Eg,the influence of K on the load-displacement curve of soil nailing is greater than that of Eg, while the influence of K on the shear force between soil and nail is lower than that of Eg.

Adopting palm as a reinforcement material for Shanghai clay, the direct shear tests are carried out to study the effect of palm on Shanghai clay strength characteristics by changing the reinforcement ratio and palm size of reinforcing material. The results show that: (1) Compared with the pure soil, the reinforced soil shear strength and cohesion have improved significantly, but small changes in the angle of internal friction. (2) The optimal rate of reinforcement is 0.6%. (3) The shear strength of shanghai clay with palm size of 6 mm×12 mm is higher than that with palm size of 6 mm×6 mm and 6 mm×18 mm. (4) When the vertical load is 100 kPa, the stress-strain curve is of strain softening type; with the vertical load increasing, the stress-strain curve is of strain hardening type. (5) Compared with pure soil, the reduction of residual strength of reinforced soil is reduced; and its resistance deformation enhance. At the same time, the reinforcement mechanism of the clay shearing strength and the effect of the palm in the clay are expounded. Therefore, the palm can be used as an effective method for reinforcing Shanghai clay.

In order to obtain the temperature distribution and frost deformation law of frozen wall, the shallow-buried rectangular freezing engineering, which is a construction of the line 3 to cross line 6 in Guangzhou metro, was studied through the model test based on similarity theory. Conclusions are drawn as follows. Firstly, the temperature of the soil closed to the ground surface drops slowly under the influence of ground heat dissipation in shallow-buried freezing engineering .And the frozen wall closed to the ground surface is relatively weak. In the process of freezing, the average development speed of internal frozen wall is about 1.5 times that of the outward frozen wall. Secondly, small amount of frost heaving deformation is generated in the initial freezing stage. The freezing construction is proceeding with high-temperature brine; and the closed frozen wall is not formed at this stage. Thirdly, when the frozen wall is closed, the frost deformation of frozen wall increases obviously at the time of the freezing construction with low-temperature brine. In general, the soil frost heave deformation tends to decrease when the soil layer depth becomes smaller because the upper soil layer is compacted. There is significant interaction effect between the upper shallow covering and frozen wall in shallow-buried rectangular freezing engineering. This implies that the upper soil layer, which will produce deformation in the advance of the freezing process, will affect the temperature field distribution in frozen wall.

In light of the importance of study of mechanical parameters of rock mass structural plane, based on a large number of practical projects and the basic statistical principle about error analysis, the applicabilities of least square method and M - estimation method for calculating the structural plane shear strength parameters, are studied. The results show that, when the gross errors are uncertain, it is hard to find the regularity that the two methods are more suitable for some certain condition. Because the data all have the given engineering characteristics, in order to make results more accurate, a new method based on the above two methods is proposed; and it is applied to calculate shear strength parameters of Lijiahe reservoir.

On the basis of a non-Newton fluid viscous damping element, fractional nonlinear dashpot element has been presented. Based on the definition of fractional derivatives, a theoretical expression for the element has been obtained. Its expression is consistent with that of the Abel dashpot. Through further comparison, it is found that the element can reflect the nonlinear acceleration characteristic of the creep curve. By introducing the element, new nonlinear creep constitutive model has been established. Based on the data from the creep experiments, fitting analysis has been conducted about the model. The results show that the nonlinear creep constitutive model agrees well with the data from the experiments and can clearly reflect the characteristics of the creep curves of the whole process, especially the nonlinear acceleration creep stage.

The key equipment of thickening process in the action of cemented paste backfill (CPB) is deep cone thickener (DCT). The underflow mass fraction of DCT is significant related to the slurry pressure. And the void ratio is an important representation parameter of the underflow mass fraction. However, the change rule between the void ratio and the slurry pressure is not clear. For the interpretation of the problem aforementioned, a new concept for the tailings thickening degree is proposed and named as effective void ratio (EVR). The EVR is referred to void ratio minus saturated void ratio. A total tailings dynamic thickening experiment is conducted. The results show that the slurry pressure is between 2 477-4 410 Pa as the slurry height is between 31-200 mm. The underflow mass fraction is calculated as 73.26%-78.30%, which corresponding the EVR is 0.433-0.191. The regression result indicates that EVR and slurry pressure follow the power function. Moreover, the paste dynamic thickening model is proposed. According to this proposed model, the paste dynamic thickening behaviour is divided into three processes: (1) linear thickening zone, with the increasing of slurry pressure, the void ratio decreases quickly almost as linear, (2) attenuation compression zone, with the slurry pressure increasing continues, the void ratio decreases gradually and the paste tends to be saturated, (3) constant thickening zone, the tailings achieve saturated state and the void ratio become constant. This study reveals the change rule between the void ratio and slurry pressure in the process of thickening and provides the theoretical foundation for the thickener design and operation.

A comprehensive laboratory investigation on the workability, compressibility and hydraulic conductivity of fine-grained zeolite-amended clayey soil-bentonite backfills is conducted via a series of slump and oedometer compression tests. Kaolin is used as the control clayey soil, and it is amended with various contents of bentonite and zeolite to prepare zeolite-amended kaolin-bentonite (ZKB) backfills. The study results are compared with those of zeolite-amended sandy soil/Na-bentonite backfills as well as compacted zeolite-bentonite liners reported in previous studies to clarify the effects of zeolite content and zeolite grain-size on the compressibility and hydraulic conductivity. The results indicate that the water content required to achieve a target slump (100-150 mm) increases with increasing zeolite content, and is approximately in the range of 0.96 to 1.18 times the liquid limit. The results reveal that the hydraulic conductivity of the zeolite-amended clayey soil-bentonite backfills is generally lower than the typical regulatory limit (10-9 m/s). The addition of fine-grained zeolite has little influence on the compressibility and hydraulic conductivity of clayey soil-bentonite and sandy soil/Na-bentonite backfills. In contrast, the addition of coarse-grained zeolite is likely to considerably increase the hydraulic conductivity of soil-bentonite backfill. Finally, a proposed empirical method is examined for predicting the hydraulic conductivity of the backfills in this study. The predicted hydraulic conductivity values are found to fall in the range of 1/3 to 3 times those obtained from the oedometer tests.

The essential researches on pile foundations are on bearing capacity of piles and interaction between the pile and subsoil, including deformation of soil and pore pressure change of saturated silty clay around the pile. Centrifuge model testing is used to study vertical bearing capacity of single pile both in saturated and unsaturated silty clay. The pile is pressed into the soil by vertical loading device, and deformation of soil around the pile and pore pressure change during the loading of pile are measured and then analysed. When saturated, the soil around pile results in pile’s softening of bearing characteristics, and the bearing capacity of pile gets smaller than in unsaturated soil. However, an obvious ultimate bearing capacity in the experiment of unsaturated silty clay does not exist. Deformation of subsoil has a significant relevance to the loading of piles. The impact of loading of the pile on the deformation of soil around the pile has a certain limit of distance, out of which the displacement of soil is negligible. The results show that the limit of distance is about 7 times the length of pile section, and a certain limit of distance exists in the impact of loading of the pile on the water pressure changes in saturated silty clay around the pile, which reflects the same rule as the displacement of soil around the pile. Displacement of soil is greater in the places closer to the pile. As the distance from the pile increases, the impact of piles on soil deformation decreases.

In order to study the evolution of internal force and the load characteristics on pile-anchor retaining structure of complex, large and deep foundation, based on the deep foundation of which the total area is about 160 000 m2 and the maximum excavation depth reaches 26 m, we have monitored the internal forces of the pile and anchor respectively in the process of foundation pit excavation, pile head with lateral loaded and different working conditions of the bolt drawing by embedded bar gauge on the retaining pile and anchor reinforcement. The results show that: (1) during the cantilever pile stage, as the foundation pit excavation the lateral pile body stress of three retaining piles presents “tension-compression-tension” and the inside pile body stress exhibits “compression-tension”. The same point stress increases. Max stress position moves down slightly. The stress-zero appearance varies depending on the length of pile. During single-fulcrum stage, along with increasing exposure time of foundation excavations, the exposed pile stress increases. The peak stress of pile appears in the near excavation area. Excavation of pile body stress tends to complex and the zero-stress point arise earlier than the cantilever pile stage. During two-fulcrum stage, pile’s reinforcing stress tends to be more complicated. Main reasons are that the excavation time of foundation excavations and the impact of factors such as tension locking of prestressed anchor. (2) structural bolting design needs to consider the maximum deformation; After meeting the threshold length of anchorage, the longer the free section, the better anchoring effect, the shorter anchoring section, the more economical. (3) without pulling force or during different tensile force, redistribution occurs in bolt stress, which is different from the those in soil or rock excavation. (4) the appearance and movement of the neutral point of lateral friction force in anchor arm are in consistence with those of the potential slip surface. Therefore, the location of slip surface and anchor arm threshold length in a deep excavation can be determined.

The external water pressure is the key factor for lining structural safety in construction, operation and maintenance condition. The traditional method for external water pressure estimation is with empirical formula. However, the effects of geology, boundary, excavation and lining construction aren’t adequately taken into account; and the solution results have risks and uncertainties. This paper reviews the general methods for external water pressure estimation, such as discount coefficient method, theoretically analytical method and numerical analysis method. The numerical results compared with the analytical results under different permeability environment and lining support forms illustrate the viability of the numerical analysis method. The numerical model scope is discussed to reduce the calculation error. The evolution process of seepage field is captured along with the tunnel excavation and lining supporting. The results show that the external water pressure on lining increases with the increase of permeability of surrounding rock and the lining thickness. The distance from the tunnel center to the boundary should not be less than 30 times tunnel diameter. Considering the transient effect, the tunnel seepage field tends to be stable within 10 days after the excavation; the water pressure distribution tends to be stable within 20 days after the lining supporting.

The mechanical properties of coal are the basic data for the design of drilling completion programs, coal bed methane development plans and construction methods; and the important factors which influencing the effect of reservoir reconstruction. The mechanical parameters of coal under different stress conditions are significantly changed caused by the existence of large plenty of endogenous fractures, structural fractures and micropores. At present, researches on the changing rules of the effective mechanical parameters of coal under different stress conditions, and the internal causes for those changing rules are relatively lacking. By triaxial compression tests, the characteristics of effective elastic mechanical parameters of medium rank coal under different stress conditions are studied. The results show that the deformation of coal under different stress conditions is significantly affected by the pore and fracture. In the elastic deformation stage, the effective elastic modulus and effective Poisson's ratio of medium rank coal increase with the increase of confining pressure. The effective elastic modulus and effective Poisson's ratio of coal present a nonlinear relationship with confining pressure respectively; and their values tend to be constant when the confining pressure increases to a certain degree. Based on the triaxial compression test, the effect mechanism of stress conditions on the effective elastic properties of coal is analyzed; empirical formulas of the effective elastic modulus and effective Poisson's ratio are given for medium rank coal with extensional fractures in it. Meanwhile, the applicability of the formulas is analyzed.

Moduli of the four stages during the compression of sandstone after high temperature varying from 25℃ to 1 000℃ are defined, through which the complete stress-strain curves of sandstone are analyzed. The modulus characteristics are analyzed as well as the ultrasonic properties. The damage of sandstone after different high temperatures is analyzed based on the damage factor which is defined by the modulus of compact stage. The research shows that the compression of sandstone after different high temperatures is of prominent staged characteristic. The changing rules of moduli of the four stages with variations of temperatures are not different, among which the modulus of compact stage has a strong relativity with the longitudinal wave velocity. The damage factor defined by wave velocity loses sight of the density and Poisson’s ratio. Avoiding the defect of Vp-method, the damage factor defined by modulus of compact stage is of greater scientificalness. Within the temperature range of 25 ℃-200 ℃, the thermal damage of sandstone is more sensitive to temperature. The results have some guiding significance to rock engineering in high temperature environment.

Ground movement induced by tunneling may cause excessive deformation or breakage accident of buried pipelines. Therefore, these problems arouse great concerns of engineers. Based on assumed distribution form of the vertical displacement of buried pipeline, the governing variational equations are established based on the energy method. The energy variational solutions of the vertical displacement of buried pipeline causes by tunneling are obtained accordingly. Using the principle of superposition, further results are extended to solve the twin-track tunnels. The validation of the proposed method is demonstrated through comparison with the centrifuge tests and cases studies. Meanwhile, factors that affect the vertical displacement of buried pipeline are also analyzed. The conclusions can be applied to practical engineering.

The combined composite foundation improved by both sand drain and cement-soil mixing piles, is a new technique of ground improvement for soft soils. It can not only accelerate the consolidation process but also enhance the bearing capacity of the soft soil foundation. According to the configuration of the pile and sand drains, this type of composite foundation is simplified as an axisymmetric model with the cement-soil mixing piles located at the center of the unit cell. The water is assumed to flow into the sand drain from the center along the radial direction and the water flows into the sand drain is equal to that flows out of it, i.e., the equal flow assumption at the soil-sand drain interface. In this way, the smear effect of the sand drain can be taken into account and the consolidation equation for this type of composite foundation is developed. Then analytical solution is obtained for the loading scheme which is applied gradually and the stress increment is distributed in a trapezoid form in the vertical direction. Furthermore, with degeneration of the obtained solution to the simple cases, the analytical solution under an instant loading is presented. Finally, the influences of the following parameters, including the ratio of influenced zone radius to sand drain radius, the loading period, pile-soil compression modulus and sand-drain’s permeability coefficient, are investigated. This analytical solution has a theoretical significance to improve the design and the calculation of this type of composite foundation.

Based on the mass conservation of fluid, Darcy law and elastic constitutive equation of expansive soil, two-dimensional equations of coupled seepage and deformation in expansive soil are obtained. Combined with the field soaking test on expansive soil foundation under low embankment of Yun-Gui high-speed railway, then both the numerical simulation considering coupling and that without considering coupling are used to analyze the swelling deformation characteristics of expansive soil foundation under low embankment. The study results indicate that the swelling deformation of ground surface can be fitted with hyperbola in the coupled case, but it increases gradually with time in the uncoupled case. The swelling deformation obtained from the numerical simulation which did not consider coupling is less than that obtained from the numerical simulation considering coupling at the same time. The relative expansion ratio decreases along the depth of foundation in the coupled and uncoupled case. In addition, the numerical calculated values are compared with test results in field. It is pointed out that the numerical simulation without considering the effects of coupling is difficult to describe the swelling deformation of expansive soil foundation under the artificial soaking condition. On the other hand, the results from the numerical simulation considering the impacts of coupling agree well with the measured results.

In-situ loading test is the most reliable method for determining bearing capacity of composite foundation. Many construction projects show that, when loading tests haven’t reached a high degree of loading, the characteristic value of subgrade bearing capacity is unable to be determined by ultimate load. In this case, the method suggested by technical code for ground treatment of buildings should be employed to determine the characteristic value of composite foundation being capacity, but sometimes this characteristic value determined by the code is too small, which will lead to the results that the engineer adopted smaller bearing capacity characteristic value of composite foundation than normal in the design, and the design results are too conservative. From this it will bring out the technology investment and the cost of engineering economy increase. disadvantages of the method determined bearing capacity characteristic value of composite foundation by in-situ loading test are analysed by comparing a group of in-situ load test data of the plain concrete pile composite foundation with a group of in-situ loading test data of natural foundation in the same site and the same condition; and the reasons for defects are discussed. This paper complements the method for determining the bearing capacity of composite foundation by the load test proposed by technical code for ground treatment of buildings, and in order to promote the application of composite foundation technique and in situ loading test.

As an important parameter of calculating the limit skin friction which is a main part of the ultimate uplift capacity of single piles in sand, the rationality of the coefficient of lateral earth pressure K will affect the accuracy of the ultimate uplift capacity of single piles. Firstly, based on the passive stress state of dense sand around uplift piles and the active stress state of loose sand around uplift piles, the coefficients of lateral earth pressure of different relative densities sand are derived considering the effects of the skin friction and the surface roughness of piles. Afterwards according to cylindrical shear failure mode, a method for predicting the ultimate uplift capacity of single piles in sand is obtained considering the development critical depth of unit skin friction. Lastly, the test results of uplift piles are analyzed by the present method and the predicted ultimate uplift capacity of single piles agree well with those measured values.

Laminar formation of sliding bed is usually regarded as equivalent with homogenate in current study of anti-sliding piles. However, this equivalent will definitely lead to some errors compared with real condition. Here, based on the deflection differential equation of the laterally loaded piles, the formulas of the displacement, internal forces and the stress of the elastic anti-sliding piles is deduced considering the different foundation coefficient of sliding bed. Meanwhile, the calculation and graphic processing programs of the internal forces and stress of the elastic anti-slide piles are written in Matlab software. This software devotes much in increasing the efficiency and the accuracy of the calculation. Comparisons were made with the method of equal effects to show that the displacement of sliding surface, the corner of sliding surface, the maximum values of the shear strength and the bending moment increases 25.76%, 18.04%, 15.6% and 4.39%, respectively, and the lateral stress of sliding surface decreases 44.91%. The study plays an important role in guiding different lithological rock masses of landslide for anti-sliding piles design.

The looseness range of surrounding rock is easy to overlay and enlarge when tunnelling adjacently underneath triple-decker mined-out area, the asymmetric movement of formation may lead to asymmetric loads to tunnel structure. Indoor similarity model test of tunnel excavation underlying triple-decker mined-out area was carried out; the ground movement of the mined-out area and internal forces of the primary supporting structure were gauged with the displacement meters, the earth pressure cells and the electric resistance strain gauges embedded in the earth. Test result of displacement predicts that in a specific dip angle range the smaller dip angle of mined-out area will cause larger settlement rate, steeper curve, slower convergence speed later and bigger settlement value. With the increase of distance between the strata and tunnel, strata disturbance degree first increases and then decreases; a certain angle of mined-out area will make the earth pressure of one side of the inverted arch where relatively far from the mined-out area significantly larger than another side; therefore, the inverted arch’s structure design should be strengthened. In the range of 15° to 30°, the existence of dip angle has little influence on distribution form and size of surrounding rock pressure; but greatly affects the internal forces of the steel arch; the larger the angle is, the bigger the primary support eccentricity is. For the fourth grade of surrounding rock, when two-lane tunnel is built adjacently(2 m) underneath triple-decker mined-out area, it’s strongly recommended to support in advance, then excavate by steps method, excavation footage should be not more than 1m, steel arch span should be not more than 0.5 m.

The orthogonal test L9(34) program is designed by taking slenderness ratio of piles l/d, ratio of pile spacing to pile diameter s/d, thickness of grouting body h as factors and the ultimate load-bearing capacity of single pile Qu and settlement of pile top under a load Sp as inspection parameters. The finite element method is used to analyze load-bearing behavior of single pile with post grouting at pile tip, and then order of factors and effect rules are got. The results show that the ratio of pile spacing to pile diameter s/d is the most important factor for bearing capacity or settlement of pile. When the s/d is larger, the effect of post grouting at pile tip on the increase in bearing capacity and the reduction in settlement of pile is more obvious. The post-grouting at pile tip can increase pile tip resistance and change the bearing behavior of pile gradually from the friction pile into the end bearing friction pile, friction end bearing pile, or end bearing pile.

In order to investigate the unsaturated hydraulic properties of wide grading gravelly soil which will be conducted as the protective layer of the geotextile clay liners geomembrane (GCLs/GM) lining in a landfill composite liners under drying-wetting cycles, the parameters of SWCC for the gravel soil were measured by using pressure plate extractors; and the four dehydration SWCCs with 0-3 drying-wetting cycles were fitted by using the equations of van Genuchte and Fredlund with 3 parameters. The results show that the wide grading gravelly soil dehydrate rapidly in low suction within 0-100 kPa, and the variation of moisture content gradually decreases when the suction is located on 400 kPa with the increase of drying-wetting cycles; the saturated water content presents convex function but the residual moisture content gradually reduces and smooths under drying-wetting cycles; there is little difference between both the models, and van Genuchte is slightly better than the model of Fredlund with 3 parameters. In addition, the experimental results were compared with clay and bentonite soils from existing literatures. It is suggested that wide grading gravelly soil, as a protective layer of the anti-seepage lining of landfill, is more conducive to the moisture and hydration of GCLs.

Shape acceleration array (SAA) is a sensor based on microelectronic mechanical system (MEMS) testing principle used to test acceleration and displacement, and it has the characteristics of high accuracy, reusable, automatic real-time acquisition. This paper presents the first use of the shape-acceleration array (SAA) technology in shaking table test of pile and composite subgrade in layered soils. We investigate the displacement response of the coupling system of pile and composite subgrade as well as soils under seismic excitations. Experimental results show that SAA can record the dynamic behavior of piles and soils in regard to accelerations and deformations. We also observe that the deformations of piles and soils are compatible only under small amplitude earthquakes. The existence of soft soil layers has a large effect on the horizontal displacement of the soil foundation.

Near blasting beneath the just completed primary support line is a special condition; it relates to many problems such as the primary support failure and subsidence. A design and construction example of an engineering of the Qingdao Metro Line 2 close (250 mm) beneath the just completed primary support line 3 tunnel, is employed, controlling vibration and deformation with measures such as the self-feeding pipe shed, tunneling crown, assisted middle hole cut, applied tensile force for the existing tunnel load, and reasonable blasting vibration control indexes are proposed according to analogy. The variation law of deformation and internal force of existing tunnel in building construction is revealed by using the finite element analysis software MIDAS-GTS for numerical analysis of 3D model. The measures taken achieve the desired effect. Primary support structure of the line 3 has no abnormal, through theoretical calculation and experimental analysis. Research results have an important reference value to blasting under special condition in design and construction.

When the horizontal reinforced concrete struts are used in retained foundation pit of large area，the cost of horizontal reinforced concrete struts will be very high and need long construction period. Moreover, large amount of solid waste will be produced after the struts been demolished. Therefore, the multi-bench retaining method is developed and was used in large area foundation pit projects. The failure mechanism of multi-bench retained foundation pit is investigated and design method is studied. The multi-bench retaining structure can fail as overall stability failure or overall overturning failure like a gravity retaining wall when the width of the bench is small. The slip surface can extend into the soil between retaining pile of different benches with the increase of the width of the bench, this leads to the mutual-effect between the multi-bench retaining piles. Separate failure can occur to the multi-bench retaining pile when the width of the bench is big enough. The application of multi-bench retaining method shows that multi-bench retained foundation pit with the use of horizontal reinforced concrete struts can be highly cost-effective and construction period of underground structure can be significantly reduced.

Aiming at high water-pressure, great ground stress, high ground temperature, large deformation, difficult supporting and other problems in the construction of deep and long tunnels, the superiority and disadvantage of tunnel construction method are conducted, such as drill-blasting method, TBM method, and TBM bored pilot+enlarging method. TBM bored pilot+enlarging method provides a new idea for tunnelling design of deep and long tunnels. Due to the remarkable differences in geological condition between deep tunnels and shallow tunnels, there are three crucial problems for TBM construction, namely, rockburst, TBM jamming (large deformation), and construction accidents (water gush, mud burst, etc.) attributed to inaccurate geological prediction. In order to detect the occurrence of TBM jamming, theoretical analysis and numerical simulation of TBM construction are conducted in deep soft rock and hard rock under certain geological conditions. The results show that the jamming occurs in deep soft rock, but never happens in intact hard rock.

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Post-cast strips are widely used in the main building and annex, and the interaction analysis is more complicated. The interaction analysis method for the main building and annex with post-cast strips is introduced. Calculation should be done separately according to different working conditions during construction, and the calculation results should be added together. The limited compression layer model is used as the foundation model, and both resilience and recompression are considered. The structure stiffness is formed step by step. For the main building with annex on medium or low compressible soil, by analyzing simplified models with different locations of post-cast strips and different pouring time, the settlement and contact pressure show the feature as follow: the later post-cast strips are poured, the smaller the differential settlement between the main building and the annex is, but the settlement of the main building is larger; compared with post-cast strips at the first span outside the main building, both the maximum settlement of the main building and the differential settlement between the main building and the annex are decreased, and the average contact pressure under the main building is lower, when the post-cast strips are set at the second span outside the main building.

Shield constructions usually have significant influences on adjacent piles due to soil disturbing, not grouting in time and shortfall grouting, which changes inner force and induces deformation and displacement. Orthogonal test is an effective and fast method to find major and minor factors on certain parameters. Based on the mode of elastoplastic FEM induced in the process of shield construction, combined with orthogonal tests and variance analysis, magnitude of shield construction influence factors on adjacent piles is got. The results show that magnitude of influence factors from large to small is distance between pile and tunnel, load applied on pile top, stress loss and properties of soil. Piles are not affected by shield construction beyond 2.5-3.0 times diameter of tunnel; and there is obvious relationship between pile settlement and pile loading which reflects state of initial stresses. Adjacent pile degree and formula are proposed according to results of significance testing of variance analysis, based on which, piles are classified into four categories: very near pile, adjacent pile, distant pile and very far away pile. The results show that there will have major impacts on first and second category piles that will be protected and strengthened, while third piles are taken measures regarding situations and the fourth piles needn′t be dealt with.

Risk factors of long inclined-shaft construction in coalmine by TBM were identified; and two-layer indicator system was established for risk assessment. Standard of risk classification was determined. Risk analysis model for long inclined-shaft construction in coalmine by TBM techniques was established on the basis of set pair analysis. Weight vector was determined by entropy weight method. Calculation method of five-element partial connection number was established and method of trend prediction was put forward by improved set pair potential theory. Trend analysis and risk evaluation of inclined wells (experiment wells #1, #2) which were constructed by TBM in Taigemiao mine area were studied by this model. The model is effective and practical for the risk analysis of mine inclined-shaft construction by TBM. As a result it provides a new way for long inclined-shaft construction in coalmine by TBM techniques

Brownish-red(Quelo) sand in Angola has formed for a long time. In low moisture content, the soil has high bearing capacity; but it will reduce largely when meeting water. Ground treatment schemes often have different views. An amount of project practice and special researches prove that, there is a obvious correlation between bearing capacity and moisture content. Through sampling in pit and in-situ tests; the physico-mechanical properties of the soil are identified; through analyzing the cone penetration test (CPT) and plate loading test (PLT ) results with different moisture content, a power function relationship between bearing capacity ( fak) and moisture content for this soil is built; and a linear empirical formula between bearing capacity( fak) and cone resistance(qc) is given too. CPT results indicate that cone resistance(qc) and side friction resistance( fs) gradually increase with depth; soil is even, but friction-resistance ratio(Rf) is small. According to the analysis, it is high risk taking the non-rolled soil (original soil ) as subsoil. For multi-storey and 9-13 storey buildings, using replacement layer of compacted fill is more reasonable than pile foundation.

Collected data from blasting vibration test is quite discrete. The technique of deleting error data and wavelet denoising are used to preprocess blasting vibration test data. In this study, standard residual sum of squares between the collected blasting vibration and the calculated fitted values using Sadovski formula are adopted as deviation basis; while wavelet denoising method is used to deal with the measured data. Particle swarm optimization algorithm (PSOA) was optimized for k and a of Sadovki formula of regression analysis. The results show that: wavelet denoising and particle swarm optimization algorithm reflect the real situation of blasting vibration test and thus improve sequentially simulation accuracy of blasting vibration test, so as to offer a good reference for blasting vibration test theory and engineering practice.

When construction embankment upon soft ground, settlement and stability are most important problems to be considered. Based on Xiaonianwei construction on Nanjing Yangtze Dike upgrading project, field monitoring and tests on embankment construction process upon soft ground are carried out. The monitoring projects contain surface settlements, layered settlements, lateral displacements of soil, soil pressure, pore water pressure and the groundwater table, etc. Based on Plaxis software, numerical simulation model on embankment construction process upon soft ground is built. The accuracy and reliability of numerical simulation model is verified by comparative analysis with field monitoring results. Then, the settlement influenced by key indicators of construction control factors, such as filling rate and filling intermittent time, is discussed and analyzed. The results show that the whole settlement increases with single filling thickness increasing; while the influence becomes little when single filling thickness less than 1 m. Hence, the single filling thickness with 0.5－1.0 m is suggested. The research results can provide a reference to construction quality control upon soft ground in similar places.

Large scale deep mining has become an inevitable trend in the development of China’s mining industry. Rockbursts and large deformation control are the research highlights in deep mining; and they are both caused by exceedingly concentrated underground- pressure of deep mining. So the aims of pressure-relief mining are to transfer or release some of the concentrated stress. These pressure relief theories, such as underground-pressure arch, bearing pressure, maximum horizontal ground stress, plate theory, the pressure-relief support and theory of axial variation, etc, and their application fields are summarized. From the pressure-relief mechanism, the stress-relief construction technology is classified simply. Moreover, the research methods are overviewed on pressure relief mining too. Results indicate that drilling blasting is a kind of flexible pressure-relief construction technology; and future stress-relief theory research would still follow the principle that the similar simulation and numerical simulation are combined with in-situ test. In general, it is an important research direction to develop FLAC3D software insetting LS-DYNA3D software in the field of numerical simulation of pressure-relief mining with drilling blasting; and it is the research & development direction to innovate pressure-relief construction technology that various pressure-relief theories are combined organically. Furthermore, underground-pressure arch and the pressure-relief support theory must still to be studied in depth.

There is a great development of underground space in the Yujiapu area, in Tianjin. The problem of anti-float is serious, because of the buried depth of the basement is deep and the groundwater table is higher. The monolayer area is about 30,000 m2; and the buried depth of the basement is about 16 m. Based on the Yujiapu north-south underground garage, the tests on pedestal uplift piles and side-grouting uplift piles are canied out. The tests show that, compared with the normal uplift piles, the pedestal uplift piles and side-grouting uplift piles have advantages of greater uplift bearing capacity and shorter pile length; so that its economic benefit is notable. The pedestal pile is better than the side-grouting piles in the aspects of ultimate bearing capacity and displacement controlling. The pedestal uplift pile is used in the garage; full hydraulic swivel-driven construction technology is used too. The successful using of the pedestal uplift piles has great significance and practical engineering value; it will be a good practical case for similar projects.

Blasting squeezing silt technology plays an important role in the marine reclamation and tidal power station seawall project construction. The thickness of soft clay that needs to be dealt with is gradually deepening with the continuous advance of marine engineering progressing to offshore and underwater shoals. The suspended seawall structure appears when soft clay is more than 12 m deep. Therefore, it is of great importance and of application value to carry out the settlement calculation and analysis. Taking Huizhou port depot revetment project for example, traditional settlement calculation method, the settlement calculation method considering buoyancy and numerical simulation method were applied to carry out settlement calculation; their results are compared with the actual monitoring results. Furthermore, the applicabilities and rationalities of these three methods are analyzed. It is shown that, the results of traditional settlement calculation method are significantly larger than the actual ones, it may not be suitable for suspended seawall; while the settlement calculation method considering buoyancy and numerical simulation method are suitable for suspended seawall because the calculation result are closer to the actual situation.

Some damages such as overall incline, horizontal misalignment in the movement joint, spalling of sealant and liner in the movement joint etc. of a metro station passageway have been found, which caused by excavation of adjacent deep foundation. In order to provide guidance for the metro security, the passageway accidents and damage cases have been described as follows: the project’s overview of the accident case is introduced including the design and engineering geology of the passageway and deep foundation; the main damage of the passageway is summarized detailedly; the main cause for the passageway’s damage is discussed based on circumstances surrounding, the passageway construction site, actual displacement data, pit monitoring data. Numerical simulations are carried out for the underground diaphragm wall and excavation construction of the foundation pit, prestressed anchorages are disturbed by the underground diaphragm wall construction and the computed passageway’s displacement is induced by drawdown. Finally, from the perspective of metro protections, the successful experience and accident protection lessons are summarized.

Salt rock is internationally recognized as the most ideal energy underground storage medium because of its good creep properties，low permeability and damage recovery characteristics. Casing structure of gas storage in underground salt rock is affected by internal pressure, material parameters and geometric size of casing which are uncertain during the operation process of gas storage. In order to evaluate effects of these random risk factors on operation safety of casing structure, a mechanical model and the structure function of casing based on Von Mises yield criterion have been established. According to the established mechanical model and structure function, the change laws of reliability of gas storage casing under the high pressure and low pressure conditions are obtained through the response surface combined with Monte Carlo sampling. Reliability analysis shows that the minimum operating pressure of gas storage should be greater than 3 MPa, the maximum operating pressure of gas storage should be less than 22 MPa, the distance between the casing shoe and the gas storage cavity should be more than 10 m. In order to ensure the safety operation of the gas storage casing, it is very important to appropriately increase the casing wall thickness and decrease the diameter of casing.

Due to spatial auto-correlation and inter-correlation among geotechnical observed data, the spatial geotechnical characteristics distribution at unknown location has to be extrapolated or interpolated by some special methods. However, classical statistical methods could not rationally resolve the problems which include selection of sample points, and comparison of spatial estimating weights between bilateral data. The distance-weighted ordinary Kriging (OK), universal Kriging (UK), and co-Kriging (CK) prediction methods for scattered data are introduced at first, which are known as the Kriging family in global geostatistics. Moreover, multi-fractal theory combining with co-Kriging (MK) is presented to depict the local singularity which should be ignored by Kriging of sliding weighted average algorithm. The performance is compared in different typical geotechnical parameters: cohesion coefficient c, friction angle and compression modulus . This study is based on the main axis (525 m long, 80 m wide) of Expo 2010 area of Shanghai, geotechnical test samples come from 42 boreholes. The performance of the different model fitness used in this study is MK, CK, OK and UK from the best to poor for parameters c and , and for parameter simulation, the sequence is MK, CK, UK and OK. The results prove that, in the most geotechnical occasions, auxiliary information would improve the prediction accuracy, and MK theory is useful tool to measure local singularity.

Basal bearing capacity calculation is one of the important issues for soil nailing wall design. In Chinese excavation engineering, the bearing capacity of soil nailing walls is usually taken into consideration with the basal stability analysis. Soil nailing wall models are established in the Plaxis3D. Finite element method is employed to study the foundation soil′s failure mode, the failure loads and the basal stress distribution of the soil nailing wall. The analysis mode in Chinese excavation codes for bearing capacity of soil nailing walls is examined based on the results from the finite element method; and some problems are detected. Referring to the bearing capacity calculation mode for the mechanically stabilized earth walls, and based on the stress distribution under the soil nailing wall, the soil nailing walls are considered as rigid footings with inclined and eccentric loads. The solutions for rigid footings with inclined and eccentric loads proposed by Meyerhof and Vesic are used to calculate the bearing capacity of soil nailing walls. Calculation results show that the solutions by Meyerhof are more consistent with the truth; so that the bearing capacity analysis mode for soil nailing walls is presented.

A method is proposed to conduct back analysis of the proportional coefficient of horizontal resistance in vertical elastic subgrade beam method for deep excavations according to the measured deformation of retaining wall. The Ucode program is coupled with the Abaqus software in order to achieve this process. This article focuses on the theory and implementation process in the back analysis. Methods for determining the controlling parameters in Ucode program and the parameters to be estimated are also proposed. The soil layer which significantly affects the lateral displacement of retaining wall can be found by parameter sensitivity analysis. Back analysis of the m values for these soil layers can improve both the efficiency of iteration and the accuracy of back analysis results. The methodology is used to analyze an actual project and it is found that the simulated wall displacements is well consistent with the measured ones. According to the back analysis results from several inclinometers, the suitable proportional coefficient of horizontal resistance of each soil layer for this project is obtained.

When underground or surface excavations are made in rock masses, the behavior of the surrounding rock material will be greatly influenced by the presence of discontinuities. Various modes of rock slope and wedge failure can be attributed to the existence of fractures in a rock mass. In order to make rock mass structure plane group reasonably, and simulate the distribution of rock mass structural plane network by computer, this paper proposes a fusion of clustering method with improved genetic algorithm and support vector machine. First of all, according to the rock mass structural plane orientation information to establish the mathematical model of structural plane grouping, the global optimal clustering center of structural plane is obtained by using the improved genetic algorithm. Then the structural plane is grouped completely with support vector machine. The application of practical engineering shows that the genetic-support vector machine clustering algorithm for grouping of the rock mass structure plane is reasonable and reliable.

If the confined aquifer is not completely cut off by the diaphragm wall during the pressure-relief process which is used for preventing the heave failure of deep excavation, the sphere of influence of ground settlement caused by pressure-relief of confined aquifer is much larger than that caused by the excavation. Therefore, the deformation characteristics of the existing shield tunnels caused by pressure-relief of confined aquifer are simulated by finite element method; and then the diaphragm wall is inserted into the confined aquifer, the effect of the length of diaphragm wall into the confined aquifer on the deformation of tunnel is analyzed. The results show that, as the length of diaphragm wall inserted into the confined aquifer increases, the settlement of tunnel decreases. But because of the deformation of wall, horizontal movement of the tunnel is considerable during the pressure-relief process. So it should be pointed out that when the tunnel is close to the dewatering well, even there is a diaphragm wall cutting off the confined aquifer, the influence of dewatering on the horizontal deformation should be paid attention to. Besides, the long-term pressure-relief process will cause severe settlement of the tunnel; so it should be avoided when the confined aquifer is not completely cut off.

Evaluation and prediction of landslide susceptibility degree are the primary task of landslide disaster prevention. Therefore, evaluation of landslide susceptibility degree is very important in a scientific and reasonable method. According to the special geological conditions of the dam site of Yansangshu hydropower station, the nine influencing factors are selected, including weathering degree, slope and so on. And then landslide susceptibility classification standards are established; the landslide susceptibility rank is divided into mild, moderate, severe and extremely severe. Catastrophe theory is used to evaluate the landslide susceptibility degree; and a new comprehensive evaluation model of landslide susceptibility is proposed. Landslide susceptibility degree evaluation method based on catastrophe theory considers the correlation between every evaluation index; in which the internal mechanism of landslide system is described truly. The results of cases studies show that this proposed method has higher accuracy and good application to landslide prevention.

Due to the effects of spectacular geological formations and high in-situ stress, the stratigraphic heave after excavation, roof collapse and floor heave in the coal seam roadway in deep steeply inclined soft rock masses are easy to appear, resulting in extremely difficulty in supporting. Through field exploration and tests of roadway in Xinji Coal Mine No.3 -700 m, this paper proposes a new support scheme by applying steel arch of shoring and unsymmetrical prestressed anchor reinforcement in roadway supporting according to the asymmetric deformation, obvious floor heave and the stratigraphic heave deformation. A numerical model is established by finite element software ABAQUS and is compared with the original support scheme. The results show that the displacement of floor heave decreases by 66%; the largest tensile stress reduces from 0.58 MPa to 0.38 MPa, the plastic zone distribution is much smaller than the original scheme; and stress distribution of supporting structure is more uniform by using the improved support scheme. The study can provide useful references to some similar roadways in deep steeply inclined soft rock mass.

Landslide is the result of the interaction among several nonlinear factors; and a large amount of field data is needed to predict it. The Mamdani fuzzy inference system(FIS) model is applied to the Badong-Zigui area in Three Gorges Reservoir Region; and the results are analyzed. Based on the 3 kinds of factors (geomorphology, eco-environment and geology), which are collected by GIS and RS, 192 rules of inference are established. The regional landslide prone zoning is mapped and the susceptibility indices are derived using the Mamdani FIS, which is developed and employed in Matlab. The area under curve (AUC) obtained from the receiver operating characteristics (ROC) based on results is 82.8%, indicating that this landslide susceptibility map is successful. With the parameters selected by spatial information technology, the Mamdani FIS using its nonlinear analysis capabilities, based on expert opinion and specific inference rules, is free from prior knowledge, simplifying the data requirement. In addition, the model could suit to different areas with simply changes in reference rules based on expert opinion, demonstrating a strong adaptability.

Drilling and blasting method is a major construction method in tunnel excavation. Blasting excavation will inevitably produce vibration disturbance on the surrounding rock. Based on the project of new Zoumagang tunnel passing through upon Dong-Shen water supply tunnel, blasting vibration control technology is studied. In order to ensure safety of the existing tunnel, the new tunnel blasting construction should be strictly controlled. Construction section is selected which is consistent with the lithological character of the cross-section. Blasting vibration is monitored and vibration law is got under field conditions of the construction. Sadovski formula of peak particle velocity (PPV) for Zoumagang zone is calculated by regression analysis of the measured data. The maximum cutting dosage, safety distance, range of vibration control and the corresponding blasting plan are formulated according the formula and standard, and are verified by simulation, and are implemented on in-situ construction. The in-situ construction measured results in cross-section show that the vibration velocity control standard and blasting designation proposed satisfy the safety requirements, so as to ensure the excavation safety of the constructing tunnel and existing tunnel. Research work has a higher significance and reference value for similar excavation works and vibration control.

Based on a series of field monitoring data of earth pressures acting on the shield tunneling segments, the earth pressures for both long-term and construction period are analyzed respectively. The results show that the depth of the ground water level plays an important role on the distribution of earth pressures in the circumferential direction. The earth pressure upon shield tunnel lining will be influenced by the stiffness ratio of ground to lining; the reasonable value of stiffness ratio is 1.5 since the soil reaction acting on segments will be relative smaller. The loads during construction can not be ignored in various strata, the segments are considered to receive larger loads if the backfill grouting pressure or the grouting ratio are larger than design. The earth pressure distribution can be divided into four stages. i.e. segments assemble stage, the backfill grouting stage, grout solidification stage and the stabilization stage. The distribution of earth pressure in the circumferential direction is uneven during construction, the earth pressure in the backfill grouting stage is 2-3 times as much as in the stabilization stage. The insights obtained from this study can contribute to an improvement of load considerations in shield lining design.

The side abutment pressure distribution, the resources recovery, the stability of coal pillar and the mining roadway are considered in determining reasonable width of full-mechanized top-coal caving with large mining height. In order to determine the reasonable width, taking the 8103 mine as the engineering background, firstly, the side abutment pressure distribution of full-mechanized top-coal caving with large mining height is studied by using stress monitoring and theoretical calculation; and 8 m in width of low stress zone, more than 28 m in width of original rock stress zone are determined. Secondly, the width of fractured zone in side coal mass of full-mechanized top-coal caving with large mining height is determined by using engineering analogy and numerical simulation, and about 4 m in width of fractured zone is determined. Finally, the stress, the deformation and fracture and displacement of the gateway excavating and the coal pillars under different widths of coal pillars are simulated by FLAC3D. The study results show that the coal pillar almost have no bearing capacity and the roadway has large deformation and failure under the influence of mining abutment pressure when the width of segment pillar is 6 m or 8 m; the coal pillar has the stronger bearing capacity and the roadway has small deformation and failure under the influence of mining abutment pressure when the width of segment pillar is 28 m or 30 m. All in all, various elements such as resources recovery, roadway support control, and secondary disaster control are considered comprehensively; and the reasonable width of segment pillar of full-mechanized top-coal caving with large mining height is determined as 28 m.

In order to estimate the seismic weak parts of a crossing-active fault urban metro tunnel more fastly and accurately, the finite element method of pseudo-static elastoplasticity is used for numerical simulation to nonlinear reaction of metro tunnel by strike-slip fault, taking the range of Beijing metro line 7 as an study object. Based on the established reasonable damage plastic constitutive model, damage index is adopted to research the failure mode of lining structure, especially the first position, process and final degree of damage. The statistic formulas estimating structural damage region and the most severely location are developed. The results show that: the damage range of lining structure is located in active fault under the effect of strike-slip fault; the destruction is the most serious at the hance. The degree of lining destruction can reduce with the increase of the ground thickness. It does not need to worry about the effect of strike-slip fault rupture on the shallow tunnel when the soil thickness is greater than or equal to the critical value of soil thickness. The damaged range of liner is related to magnitude and soil thickness, and the location of the most serious damage changes along with soil thickness. The obtained results play an important role in seismic design and safety evaluation.

By properly selecting the main physical and mechanical parameters of surrounding rock, a model for calculating water inflow of a large underground water seal oil cavern after the whole section excavation is established based on porous elastic continuum fluid-solid coupling theory. And the groundwater seepage field and displacement field of Huangdao oil storage underground water seal cavern are analyzed with numerical simulation. By the comparative analysis of different grouting mode and different thickness of grouting case, it is found that it is not a fact that the greater the thickness of grouting circle of cavern, the better control effect of the seepage flow. There is a relatively economic and reasonable threshold. The results show that the best way of post-grouting is to form a whole section closing grouting circle, and the best thickness of grouting is 5 meters.

The deformation of rock mass around underground facility is confined by excavation face. Under the confinement, the spatial effect of excavation face is remarkable. Field test was performed to investigate the characteristics of the spatial effect of excavation face. An empirical hyperbolic tangent formula is proposed to describe the spatial effect. The stability of an underground cavern was analyzed using the proposed empirical formula. It is shown from this study that for a certain section, the spatial effect is not the most remarkable when the excavation face is passing the section. For rock mass of low quality, the spatial effect is less significant than that of high quality. The total displacement could not be obtained using the conventional monitoring method, which takes influence on back analysis of mechanical parameters of rock mass. The standard for stability control could be obtained using the principle of spatial effect. This study will benefit the understanding of the spatial effect and provide the reference for the stability control of underground facility.

For a nuclear power and water tunnel project, a large-scale three-dimensional finite difference Flac3D model is established to simulate the seismic response under the action of seismic waves schedule in tunnel portal section, adopting nonlinear dynamic analysis method. Simultaneously, two-dimensional finite element model of backfill high-slope is created for slope stability analysis of tunnel entrance under the action of earthquake ground motion to draw the sliding surface of slope position and dynamic time history curve of safety coefficient. Through the input of the site seismic wave and the investigation of the structure response characteristics of the tunnel entrance and slope, duration curve of tunnel lining force under seismic waves action and tunnel lining figure can be obtained. Meanwhile, high slope safety factor of tunnel can be given. The analytical results show that the seismic weak parts of the tunnel entrance are at tunnel spandrel and the sidewall. The analytical method and conclusions have a certain reference value for the seismic design of tunnels.

In light of the effect of soft soil rheology, the time effect of rheology should be considered in excavation analysis. Due to the excavated and structural construction conditions, construction period is prolonged, therefore time effect is particularly significant in the construction process. For the project of Shanghai Zhongshan Hospital, the finite element model is built to simulate the construction process of top-down excavation of foundation pits. The calculated displacement of diaphragm wall and soil is compared to the measured one in various operating conditions during construction. The results show that the model can reasonably reflect the impact of excavation on the structure and the surrounding environment, and rationally simulate the time effect of excavation. The construction process of top-down excavation and the excavation period is relatively long, so the construction process and the construction time should be reasonable arranged to control the deformation of structure and soil and protect the surrounding environment.

As a north-westward fault zone located at the Western side of Yishu fault (in Shandong section of Tan-Lu fault zone) controlling Changqing-Linyi moderately strong seismic belt, the in-situ stress state presented in Mengshan fault zone plays an important role in the hazard research on the seismic activities in central Shandong. The hydraulic fracturing stress measurements of two deep boreholes located in the vicinity of Mengshan fault zone have been carried out; resulting in the maximum horizontal principal stress SH as 7.0-17.0 MPa and the minimum horizontal principal stress Sh as 5.0-11.0 MPa. The measurement results show that the relative size of triaxial principal stress at the depth over 300 m tends to SH＞Sv≥Sh, and that tends to SH＞Sv＞Sh in the range of the depth between 400 to 450 m. The direction of the maximum horizontal principal stress presents NE-NEE, which is consistent with results acquired from other data. The average values of the lateral pressure coefficient obtained by measured data are maximum lateral pressure coefficient KHmax=1.54 at Borehole ZK134 and KHmax=1.38 at Borehole ZK8. According to Byerlee’s law, Mengshan fault zone lies in a relatively stable in-situ stress state, ? m (the ratio of the maximum shear stress to the average principal stress) presented in two boreholes shows little change between the years of 2010 and 2011 indicating that the fault zone is in a steady state at the moment.

According to observed deformation data in underground powerhouse excavation of Baishan pumped storage station, a parameter inversion method based on the response surface methodology is put forward. Using the response surface methodology, the nonlinear relationship between unknown rock mass mechanical parameter and surrounding rock deformation is proposed. Applying the finite element method, coefficients of response surface function are identified. Defining the objective function of parameter inversion, the problem of parameter inversion is changed into optimization. Quasi-Newton optimization algorithm and genetic algorithm are adopted to solve the objective function and get rock mechanical parameters. Based on rock mechanical parameters which are identified by parameter inversion, excavation deformation of surrounding rock is simulated. The study indicates that deformation of surrounding rock simulated by finite element method give a good agreement with in-situ observed data in underground powerhouse.

Using the strain hardening elastoplastic constitutive model which is suitable for numerical analysis of deep excavations in close proximity to sensitive properties, the effect of the anchor on deformation and force of double-row piles is discussed. Increasing the anchorage angles can effectively reduce not only the maximum horizontal displacement of double-row piles but also the bending moments of the back row piles. Increasing the anchorage forces can only effectively reduce the maximum horizontal displacement of double-row piles. The bending moments increase when the anchorage force is larger. In the actual design, we should choose the possible larger angle between anchor and the back row piles and actively control the anchorage forces along with the monitoring.

Concerning on the blasting excavation of division pier where free face has formed as one side of the deep trough was excavated, in order to study the effect of blasting on the division pier, dynamic responses of vibration, stress and displacement of the division pier were analysed under blasting impact load. In addition, both the blasting excavation way was improved and the excavation procedure was optimized. The study shows that the division pier dynamic responses under blasting impact load are caused by the reflection and superposition of blasting stress wave. So selecting proper reserved rock thickness could reasonably utilize this reflection and superpositon to impair dynamic responses of the division pier under blasting impact load and consequently the resulting dynamic unstability risk is also reduced. This research result has guiding significance on engineering practice.

Based on the Boussiesq solution, a method for computing the distribution of the stress and the deformation in homogeneous soil with several different kinds of loads including rectangular loads and strip loads acting exclusively on the surface of a half elastic space is given by means of integration of the Boussiesq equations of a concentrated force acting on the surface. The integration is realized by numerical integration, the composite Simpson’s rule, with dividing the acting area of the distributed loads into numerous tiny rectangles. Meanwhile, the deformation of discrete pile elements, which derives from the finite difference analysis, is given with pile subjected to concentrated force or moment on the pile top. In the same way, deformation of discrete soil elements around the pile is given based on the Mindlin solution. With the combination of the deformations of pile and soil elements, the interactions between discrete pile-soil elements are calculated to solve the responses of “active pile”. Then, combining the analysis of soil in free field and that of “active pile” mentioned above, with the displacement of free field imposed on the pile, we thus get solutions of the stress, moment and deformation along the passive pile. Consequently, a method which can be used to calculate free-field movements and stress of soil, strain and stress of “active pile”, as well as the responses of passive piles subjected to different kinds of external loads acting at the surface of soil, is given based on the analysis above. The validity of the method proposed above is testified. A pile subjected to a rectangular uniform load at the surface of soil nearby is taken as an example. Comparisons are made between results from the method proposed in the paper and those from finite element method (FEM), which testifies the method is reasonable. Furthermore, a project case of piled bridge abutment is taken for verification. Results from the method given above are in good accordance with the original data from the in-situ test from the published paper. Therefore, the method could be used to calculate the response of bridge piles with embankment loads nearby.

According to the construction of Tianjin Metro Line 2 passing under a masonry building, the finite element model is established to analyze the influence of tunneling on the ground surface and the surface masonry buildings. The calculated results which adopt the small-strain constitutive model are compared with the field measured data. The results are also compared with the conclusions obtained by the hardening soil constitutive model. The further analysis shows that both the maximum settlement and the width of traverse settlement trough predicted by small-strain model achieved better agreement with the practical project. And both the maximum settlement and the width of traverse settlement trough obtained by the hardening soil model are larger than the results obtained by the small-strain constitutive model. During the tunnel construction, the masonry building tilts to the axis of the tunnel. The rate of inclination obtained by the small-strain model can also consistent with the field data. Therefore, the small strain response of soil should be taken into account during the settlement investigation of buildings and ground surface induced by shield tunneling.

The time history analysis method of dynamic point safety factor is established based on safety margin, in light of the dynamic response of geosynthetics reinforced soil slope is very complicated, and existing methods are difficult to use for it. The nroposed method is used to evaluate the stability of geosynthetics reinforced soil slope, taking into account both horizontal and vertical seismic action. Based on the theoretical analysis, the dynamic point safety factors of the soil, geosynthetics and interface in the geosynthetics reinforced soil slope numerical model are defined. According to dynamic point safety factor method, through using a computational aids, the dynamic characteristics data is recorded, calculated and stored during computation process; and the dynamic point safety factor of the geosynthetics reinforced soil slope numerical model is figured out. The results show that the engineering applicability of method is well. The method reflects the relatively weak structure more clearly in the engineering, so as to provide reference in slope seismic design; vertical seismic action has greater influence on the stability of geosynthetics and interface, but smaller on soil.

This paper adopts laboratory experiments and numerical calculation to analyze the stability of high cutting loess slope. Taking the cutting slope in the site of Huanneng electrical plant ,which islocated in Huanxian county, Gansu province , as an example, the linear elastic finite element method is utilized to attain the stress path of soil mass on the potential failure surface under multistage excavation. Then based on this stress path, triaxial shear tests are conducted on specimens with two moisture contents. With the strength parameters obtained from these tests, elastic-plastic finite element models against different excavation ratios are made to figure out its stress field. Afterwards comparison between the shear strength and shear stress on the slide surface reveals the mechanism of slope failure. Results show that the stress path (in p-q space) of soil on the prospective failure surface displays a trend that the mean stress p decreases with excavation while the shear stress q decreases at first then increases slowly. The effect of excavation on the potential surface changes from unloading at the beginning to loading. Failure firstly occurs at the shoulder of the high slope and then expands to lower area with the excavation process until a connecting yield surface in the slope develops. This mechanism is typical of top-driving landslide mechanism.

The coupled thermo-hydro-mechanical (T-H-M) model for dual- pore-fracture media was degenerated into a model for single pore media; then this model and the gradient of rock dilatancy was introduced into the FEM code developed by the first author; also the Mohr-Coulomb yield criterion was used and the effects of dilatancy of plastic rock on porosity and permeability of rock mass were considered. Aiming at a model of hypothetical nuclear waste repository in a saturated porous rock mass with a laboratory scale, five computation cases with different values of rock dilatancy gradient were designed; then the corresponding numerical simulations for a disposal period of 4 years were carried out; and the states of temperatures, normal stresses, plastic zones, porosities and permeabilities, pore pressures as well as flow velocities in the rock mass were investigated. The results show that：compared with the case without considering dilatancy gradient, the distributions of normal stresses, porosities and permeabilities, pore pressures and flow velocities correspond to obviously the distributions of plastic zones, so some “shearing effects” are presented; all of the values of normal stress, areas of plastic zones, porosities and permeabilities, pore pressures and flow velocities increase with the raise of given dilatancy gradient.

FLAC3D software is used to establish numerical simulation model of soil nailing wall based on the basic parameters and dimensions of the model obtained from the physical model of soil nailing wall destructive test. The excavation and supporting process of the foundation pit are simulated by the numerical model, the horizontal displacement along the depth direction of the wall and the axial force of each layer soil nailing as well as the relationships between them are monitored. After the supporting process, vertical loading are exerted on the coping until large deformation of the wall appears in order to study the working conditions and the damage process of the soil nailing wall under the overload conditions, then compared with the results from the destructive test of the physical model for soil nailing wall. The study results show that the bottom horizontal displacement of the wall during the excavation stage is larger than at top, and in a spoon-shaped distribution; soil nailing axial force in the vicinity of maximum horizontal displacement of the wall is also the largest. If deformation of silty sand soil nailing wall is more than 4 ‰ of excavation depth, the stability of the wall would reduce greatly. When there is no soft substratum under the silty sand soil nailing wall, under the overload on the ground, the destruction form is the damage in the wall, and shows that a part of the soil slids down along the slip face.

Grouting-screw pile is a new type of uplift pile which uses a construction technology innovation combining boring and secondary grouting, has been carried out in soft soil area. In order to conduct a further research on its bearing characteristics, so that the pile can be widely promoted, a three-dimensional finite element numerical simulation analysis of its uplift bearing performance and mechanism is carried out. Firstly, the numerical simulation of pile-soil interface indoor large direct shear test is done to get the pile-soil interface parameters. Secondly, the three-dimensional finite element numerical simulation analysis is done by using the pile-soil interface parameters obtained. Finally, through the numerical simulation, the uplift load-displacement curve and the distribution of axial force of screw piles for different values of S/D (ratio of screw pitch to pile diameter) are obtained; the development of plastic deformation of soil around the pile is observed. Numerical analysis shows that owning to the increase of skin friction of pile caused by the "mechanical occlusion effect", the ultimate uplift resistance bearing capacity of screw pile increases by 3~5 times than circular cross-section pile's; the bearing capacity is related to S/D, when the S/D equals optimum, the initial tangential stiffness of the load-displacement curves, the ultimate bearing capacity and the continuous arched plastic deformation zone of soil around the pile equal maximum.

It is difficult to forecast and control the deformation of foundation pit engineering. A time series forecast method of foundation pit deformation based on wavelet transform, least squares support vector machine (LSSVM) optimized by particle swarm optimization (PSO) and autoregressive moving average model (ARMA) is proposed. Firstly, the foundation pit deformation series is decomposed and reconstructed into trend series and random series. Secondly, the trend series future values are forecasted by PSO-LSSVM model; while the random series future values are forecasted by ARMA model. Finally, the sum of trend series and random series future values are used as the final forecast value. This method is used to forecast the deep horizontal displacement of a foundation pit in Kunming. Wherein, the latest measured data of early working stage is used to build forecast model; and the model is used to forecast the later working stage deformation. The result is satisfied.

Large scale direct shear tests on remolded colluvial mixture samples were carried out in laboratory on the basis of gradation analysis. The deformation and strength characteristics of colluvial mixture with different rock particle contents were studied combined with simulation by two dimensional particle flow code PFC2D. By synthesizing the numerical and testing results, it is concluded that the colluvial mixture with higer content of rock particle behaves strain hardening. Colluvial mixture samples exhibit shear dilatation characteristics at low normal stress level, and tend to have shear contraction at higher stress level. If the rock particle content is less than 40%, the mechanical characteristic of colluvial mixture is controlled by soil; while this content is greater than 80%, its mechanical characteristic is influenced by rock alone.

The sand liquefaction problem has been one of the important topics in soil dynamics and geotechnical earthquake engineering. Based on a project of the Middle Route of South-to-North Water Transfer, physico-mechanical parameters of soil have been obtained through field and laboratory tests. And the dynamic numerical analysis on the liquefied sand foundation of the main canal which has been reinforced by compacted gravel piles is conducted with FLAC3D. The results show that, for the drainage of the compacted gravel piles, the excess pore water pressure and pore pressure ratio in the saturated sand foundation of the main canal bottom have been significantly reduced compared to ones before reinforcement. Monitoring curves of the saturated sand in the bottom of the main canal show that, with the duration of the seismic loading, the peak values of the excess pore water pressure and pore pressure ratio in the saturated sand foundation decrease significantly compared to ones before reinforcement; and the time-history curve declines quickly when to the peak value, which keeps essentially unchanged before reinforcement. For the drainage and compaction effect of the compacted gravel piles, the liquefaction of the sand layers, in the bottom of the main canal, and from the outside platform of the embankment to the bottom of the slope foot, is eliminated effectively. And no liquefaction occurs in the saturated sand foundation of the main canal bottom after reinforcement.

Vacuum preloading technique without sand cushion layer has been successfully applied to the weak foundation reinforcement; but it is difficult to shorten construction period due to the low permeability of weak soil. Intermittent air injection is proposed to increase the drainage rate for vacuum drainage. The combined method of vacuum preloading and air injection is investigated for different conditions of the injecting positions and air pressures based on finite element simulation. Seepage velocity, drainage rate and seepage gradient are compared and analyzed before and after air injection. The simulation results show that the air injection can improve the efficiency of vacuum drainage, so as to enhance the foundation reinforcement and reduce preloading time of the vacuum loading. The efficiency of injecting air below the drain boards is better than that above the bottom ends of boards. And in the case of not breaking through the foundation in the air injection, the greater the air pressure is set, the better effect of reinforcement will be. The combined method of vacuum preloading and air injection could be widely used in the improvement practice of weak ground.

A 3D numerical model for flowing groundwater is built based on field vacuum well point dewatering test. Through comparison of observation data and prediction data calculated from numerical model, influences of the vacuum negative pressure and the interval among dewatering wells on the dewatering effect are studied. Variation characters of the seepage field around the vacuum well point are described; a conception of three areas, i.e., coupled field area, transition area and gravity field area is proposed; and changing law of seepage field with negative pressure and depth of well point was obtained. Comparison results show that the numerical model can reflect the relationship between the water level in the observation well and the water yield well. This method can be used in analysis of vacuum well point dewatering test and provide a reference for practical design.

Research tools for direct shear of geomaterials contact surfaces with strain softening constitutive characteristics is more limited, based on FLAC, strain softening constitutive contact element models is achieved in this paper. Using this element models, the direct shear tests are simulated; the relationships between the shear strength parameters evolution for contact elements and the formal features of shear stress-displacement curves are deeply studied. The progressive failure process of the contact surfaces and the variation characteristics of the internal shear stress are reproduced in the simulation results. The studies have shown that the variation of the friction angle has a major impact on the formal features of shear stress-displacement curves.

Space distribution of foundation pit engineering for metro transfer station, which consists of vertically crossed station excavation, connected aisle and running tunnel, is complex. Numerical simulation method is usually used to analyze the construction impact of pit on adjacent buildings. Because of complicated structure and large excavation size, it is difficult to establish an integrated model to simulate construction process with single microcomputer; and numerical method does not work smoothly due to a large number of grids. In the numerical simulation of Qianshan Road metro station in Hefei, in order to overcome this problem, the complex metro foundation pit is divided into global model and one local model. The ultimate results of global model will be exported as a result of initial displacement field in local model; and then the local model is further excavated to study the influence of pit construction on neighboring buildings. Taking inverse distance weighted method and elementary interpolation method for examples, two kinds of initial displacement field of local model will be obtained by these two approaches. The calculating results of two methods are compared. It is shown that the results obtained by using displacement superposition method, which is consistent with the ones obtained by calculating separately, can used as the results of overall model approximately. The feasibility of displacement superposition method is verified. Comparing the inverse distance weighted with the elementary interpolation method, the former has a higher precision than the latter. The results play a guiding role in numerical simulation of complex foundation pit engineering.

It is more likely to cause the collapse of tunnel surrounding rock and water disasters under the action of the coupling effect of the groundwater seepage field, the stress field and the damage field. First of all, surrounding rock is regarded as the isotropic continuum material, and the elastoplastic damage constitutive model of rock is established based on the Drucker Prager criterion. The fully implicit return mapping algorithm is adopted to achieve the numerical solution of elastoplastic damage constitutive equations. Secondly, according to the dynamic evolution formula of permeability coefficient in elastoplastic state based on the above research, the elasoplastic stress-seepage-damage model of rock is established; and the coupling solving iterative method of many fields is presented. Back analysis program is compiled on the basis of the principle of differential evolution algorithm in order to solve the problem that elastoplastic damage model involves many parameters and not easy to determine, and the damage parameters are inversion; Finally, the corresponding coupling program of the elastoplastic stress-seepage-damage is compiled and parameters inversion program are compiled using C++ language respectively. The following calculations are conducted by using the programs: (1) The performance and the correctness of the intelligent back analysis program are analyzed, comparing the inversion accuracy and the convergence rate of the differences between the different strategies, the cross factors and the variation factors. (2) The calculation results of the displacement field and the stress field by the elastic model and the elastoplastic model are compared. (3) The pore water pressure and the seepage flow are calculated without considering the effect of mechanics. (4) The interaction rules of the stress field, the seepage field and the damage field of tunnel surrounding rock are calculated using the coupling model. The results show that the problem of damage parameters which is difficult to determine can be better to solve in damage model by the back analysis program based on differential evolution algorithm. It provides effective method for the calculation parameters are acquired not easily determined in practical engineering. At the same time, the macro failure of rock material can be more realistically reflect through the interaction of the stress, the seepage and the damage of the built coupling model. The calculation program which provides a method for the engineering construction affected by groundwater severely can simulate the coupling characteristics of the groundwater seepage field, the stress field and the damage field. The study of this paper lays a solid foundation for the coupling calculation of the later period for actual tunnel engineering.

In-situ stress is an important factor for underground mining and construction. We usually use back calculation combined with field measurements to obtain the accurate in-situ stress values. Based on the monitoring data of a certain complex copper-nickel mine, we establish a 3D orthogonal numerical model and use this model to obtain the difference between the measured and calculated values, the sum of the squares of the minimum objective function optimization of in-situ stress. Finally, the genetic algorithm of intelligent algorithm is used to optimize the objective function so as to acquire the original rock stress field in this copper-nickel mine. Test sample validation results show that the relative error between measured and calculated values within 10%; it is proved that the intelligent recognition method of in-situ stress is reliable in some extent and will provide a more viable method of in-situ stress field for complex geological body.

The structure effect of joint network rock mass on seismic response of underground cavern is studied. Based on the discussion of generating principle of two-dimensional joint network, five characterizing parameters, i. e. joint density, joint orientation and its discretization, joint trace length and its discretization, are identified. The powerhouse cavern of Dagangshan Hydropower Station is taken as a study case here. The results indicate that in the precondition of a same seismic level, seismic displacement increases with increasing the joint density. Seismic displacement also increases with the joint inclination increase at the range of 0°-80°. If the discretization of joint inclination is considerable, the seismic displacement is of positive correlation with joint inclination discretization, yet if the discretization of joint inclination is comparatively small, this correlation is ignorable. Seismic displacement increases with increasing the joint trace length increase. At last, little relationship between joint trace length discretization and seismic displacement has been found. Those findings may provide certain reference for the aseismic design of the underground caverns.

The three-dimensional general slope and steep slope as numerical models are used to research the inhomogeneous slope reduction scope by the field variables based on finite element strength reduction method. In the study, from some scholars research results, both rock material’s shear strength parameters and tensile strength parameter T are reduced in ABAQUS. In light of the current shortage in existing slope stability criterion, the point mutant which sites on the relationship curves between the ratio of the feature point displacement’s increment to the strength reduction coefficient’s increment and the strength reduction factors is applied to determine the critical state of slope. The results show that the reasonable safety factor can be obtained only when the local reduction in the cohesion of similar circumstances is implemented and suggests that the overall strength reduction can be used for the rock mass difference slope, whereas the more reliable results can be obtained for the relatively soft local reduction in the high and steep three-dimensional slope. Compared with the traditional feature point displacement criterion, the (the relationship between feature point displacement increment and the strength reduction coefficient increment ratio and strength reduction factor) method is proved to be practical and reasonable. Meanwhile, the safety coefficient of bridge foundation is calculated based on the criterion, so as to provide a theoretical basis for the control of the bank slope.

By introducing two covers, namely, the mathematical cover and physical cover, the numerical manifold method can solve continuous and discontinuous problems in geotechnical engineering in unified way. At present, the application of NMM is mainly limited to two-dimensional analysis which is not realistic for many underground engineering. In this paper, three-dimensional numerical manifold method based on hexahedron element is proposed; and two kinds of high-order displacement functions are used as the cover function. The stiffness matrix, loading matrix, displacement resistance matrix are given according to the cover function; and the methods of handling rank deficiency induced by high degree polynomials as local approximation is discussed. Corresponding program is made by Matlab. One simple example is calculated by the program and the numerical results, being compared with the result of other methods, proves its correctness and effectiveness. It shows that the solution accuracy of numerical manifold method will be improved, when high-order displacement function is used. An example of underground chamber is also presented. Finally, the prospects of the method in tunnel and underground engineering are given.

Xiaonanhai landslide in Chongqing city is a high landslide occurred in relatively low seismic intensity regions, its causes have been puzzled. This paper is based on the related research materials of Qianjiang Xiaonanhai, through the recovery of the Xiaonanhai slope instability analysis, to calculate the seismic force’s critical conditions that make rock mass collapse sliding. Only after the topographic ampliflcation effects of seismic waves can landslide start. In order to further validate the calculated conclusions, by using UDEC software, a typical two-dimensional space model of the Xiaonanhai is established. Applying the corresponding seismic force on the slope to simulate the whole process of landslide, as to research in the mechanism that a steep slope parallel to the surface of the structure controlling the high rocky slopes triggered by topographic amplification effect under earthquake. The results show that, in the process of seismic wave propagation, the high and steep terrain with a parallel slope controlled by steep structure plane, have a significant amplified effect on seismic wave. Amplify peak acceleration-the increasing amplitude forces rock mass along the controlling structure planes which parallel with slope to crack quickly-slip along the gently dipping levels-high-speed detach from the slipping source region-huge potential and kinetic energy drive rock mass to do long-distance movement; meanwhile, accompanied by disintegration, collisions between particles and scraping effect, even with two-phase or three-phase fluid properties, which is the movement mode of this slope. Analysis reveals that the particle acceleration in the slope body has terrain amplification effects under the action of seismic force. Comparing the speed amplification factor of monitoring points between structural surface and bedrock, it is proved that the slide starts with a greater acceleration, when faces with discontinuities structural surface which parallels, to the slope, the dynamic response of slope becomes strong and eventually lead to slope’s instability.

The dissipation process of excess pore water pressure could be spread out by using permeable pipe pile. Furthermore, the negative effects in pile driving could also be eliminated. Based on FEM and the permeable pipe pile calculation model built by ABAQUS finite software, the simulation of permeable pipe pile penetration and soil consolidation could be realized. Throughout the experiment, the numerical results are validated by contrasting CEM. Meanwhile, the variations of displacement field and excess pore pressure field created in permeable pipe pile penetration process were clearly described. Compared soil consolidation around static pressure pile and permeable pipe pile, it is shown that permeable pipe pile could accelerate excess pore water to dissipate and achieve a significant promotion of pile bearing capacity in a short time.

The thesis summaries China’s recent situations of geophysical prospecting in coral island and reef. Combined with the In-situ borehole test, three regular geophysical methods are adopted in the investigation of a coral island; their applicabilities and results are specified. It is shown that the active surface wave(ASW) and marine seismic reflection(MSR) can achieve satisfactory results; but the resistivity method is not suitable for coral island and reef. Apparent velocity profiling of ASW method figures out the geological stratigraphic sequence of coral clastic deposit and underlying reef limestone. MSR does well in the distinguishing the deposit interface of outer reef flat, seaward slope, offshore and discovers the unsymmetrical structure of sea bottom, deposit between the northeast and southwest survey line, which is probably related with the marine hydrodynamics in the coral growth and development. In-situ borehole test showes that the loose coral clastic sediments has little difference in electric resistivity with the reef limestone; therefore the resistivity method is overall not suitable for the geotechnical profiling for the reason of the same order of magnitude in electrical resistivity.

The caves not tamped back of vault lining of the excavated metro would destroy the soil layer above the metro tunnel, which can develop to ground and became the big dangerous to the traffic and buildings. The prediction aquifers and interface between rock and soil is important thing to construction safety in excavating subway tunnel. The landsonar method has been used to solve those problems and got good feedback. Three caves of 2 m long were found in the Landsonar time-section of 60 m long survey lines in metro line-6 in Tongzhou, Beijing, which cross with Jing-Ha railway under ground surface of 21 m depth . The left and right survey lines are along the median of subway tunnels, surrounding rock of which are alluvial land and miscellaneous fill soil. On the Landsonar time-section of 50 m long survey line along the median of subway tunnel of Line-4 subway of Nanjing, it can be found that 9 caves and looseness region whose depth were around 8 m, which lead the soil body above them to loosen, and five developed to the asphalt pavement. There was another survey line with a collapse. From the Landsonar time-section, it can be seen that the collapse only developed to the clay layer of 4m depth, but the looseness already developed to the asphalt pavement.

In the construction process of pipe pile, the pile blasting or crack diseases often appears. The real-time dynamic sensing monitoring technology of quasi-distributed fiber Bragg gratting(FBG) and distributed sensing monitoring technology of Brillouin optical time domain analysis(BOTDA) are applied to pile driving into soil layer monitoring. The data processing method of distributed optical fiber sensing(DOFS) technology is proposed; the pile driving processing model experiment was designed. The experiment results show that: the FBG sensor can be well used to dynamically monitor the strain variation characters in the process of pile driving; it also can reflect the strain variation rules in pile different parts varied with soil depth; BOTDA distributed optical fiber sensor can monitor the pipe pile body strain variation characteristics during pile adaption (suspended) when driving; according to the strain changes, it can be used to analyze the eccentric loading level and estimate whether the pile cracks and fails, etc; research on the pile-soil interaction rules in the process of driving. The experiment results also show that: the combination of FBG and BOTDA optical fiber sensing monitoring technology in the monitoring quality of piles driving into soil layers has the more advantage; the combined technology has wide application prospect.