Ground source heat pump (GSHP) is a new type technology for the use of the superficial layer energy. According to the law of conversation of energy and the law of conversation of mass, the equation of heat transfer, the equation of seepage, the equation of continuity and the constitutive equation of thermo-hydro-mechanical (THM) are established respectively. The whole displacement and deformation diagram of single-well and the failure criterion are obtained through simulating the flow zone with software COMSOL. The results indicate that: (1) The pressure gradient increases with elevated distance from the well, and trends to a steady value eventually. (2) The goodness of fit is good by comparing the result obtained from the heat transfer model and actual engineering measurement, which shows the reasonability and validity of the thermo-hydro-mechanical coupling model.

It is important theoretical significance and application for the failure mechanism of rock and parameter selection of fracture surface that failure property of rock and roughness of fracture surface are studied. The unloading fracture property of rock, micro-mesoscpic characteristics of fracture surface, and the correlation between fractal dimension of fracture surface roughness and unloading rock mass strength are revealed under high stress, by adopting high precision of three-dimensional 3D laser scanning and scanning electron microscope (SEM), combined with fractal theory. The macro-fracture property of marble specimen is converted from shear and tensile-shear complex to tensile fracture development. The higher the initial confining pressure and the faster the unloading rate, the main fracture surface is more fluctuant and rough. But The higher the initial confining pressure and the slower unloading rate, the main fracture surface is more flat and smooth. With the increase of unloading rate, the microscopic fracture of the marble is gradually from traverse crystal sheared, tensioned-sheared complex along crystal face and traverse crystal, to tensioned or splited along crystal. The friction angle of unloading rock is larger, but the cohesion is smaller with the fractal dimension of main fracture increases.

At present, most of the elastoplastic constitutive models for unsaturated soils are verified by using test results of unsaturated compacted soils. In situ, other types of the soils, such as alluvial soils, are often in the unsaturated states. Hence, it is necessary to study if the existing elastoplastic models for unsaturated soils are suitable for unsaturated alluvial soils. A series of triaxial tests on unsaturated Shanghai layer ③ soil were performed with suction being controlled. By using an elastoplastic model proposed by the first author for predicting the hydraulic and stress-strain behaviour of unsaturated soils, the model predictions were made on the tested conditions. Predicted results are compared with those obtained from drained triaxial compression tests on unsaturated Shanghai layer ③ soil during shear loading. The comparisons indicate that the model can reproduce the hydraulic and mechanical behaviours of undisturbed Shanghai soft clay very well. Therefore, the model is not only applicable to unsaturated compacted soils, but also is suitable for unsaturated alluvial soils.

Typical rock samples of weak broken surrounding rock are collected from Tianpingshan Tunnel for Guiyang-Guangzhou railway. The conventional triaxial compression and triaxial compression creep tests are also carried out in the test room. Based on the results of rock tests, the creep characters of carbonaceous shale are studied. Only decelerating and steady creep stages appear under a low stress level. In the higher stress level, accelerating creep doesn’t appear. However, increasing confining pressure has raised the yield strength of the rock to some extent; and the elastic modulus also tends to increase. According to these, the viscoelastic plasticity strain softening creep model of the carbonaceous shale with whole creep process is established; and the constitutive function of this model is deduced under three dimensional stresses with its parameters confirmed. The creep parameters are identified by least square method. The comparison between creep model and test curve shows that the proposed creep model can reflect the creep characters of carbonaceous shale in background project; and it can be used to study the creep properties and stability of weak broken surrounding rock of this tunnel.

The effect of structure is important for the deformation and strength of marine soft clays. The replacing depth is also related to the structure of soft clays during the dealing progress of soft foundation, in which the blasting-based squeezing and replacing method is used. The structure may be an uncertain factor to evaluate the settlement and the stability of the embankment. In order to explore the effect of structure on the settlement of the foundation, a compression model of structural soils is established for analyzing the compression characteristics of marine soft clays quantitatively. The calibration method of model parameters is also given. The compression model is verified by the experimental data from literatures. The results show that the model is not only effective for predicting well the deformation at the 1D stress state but can be used to describe the compression characteristics at triaxial stress state. Then the model is adopted to analyze the compression characteristics of marine soft clays in Xuanmen area, Zhejiang province. The effect of structure on the compression deformation of soft clays in the area is simulated well by the new model. The model offers a quantificational method to predict the settlement of the embankment in the area. Furthermore, the model will be helpful for reinforcing the theoretical basis for design and construction of the embankment in the structural clay area.

Through analyzing the influence for washing process of rock-salt cavern with coupled mechanical-dissolving effect, mechanism of washing process of rock-salt cavern under coupled mechanical-dissolving effect has been studied. The research results show that during the washing process, influence for rock-salt cavern shape by coupled mechanical-dissolving effect can not be ignored. The mechanism of washing process of rock-salt cavern under coupled mechanical-dissolving effect is that because of dissolving effect the mechanical properties of wall rock of rock-salt cavern within the scope of influence by water has been changed; and then because of the variation for the mechanical properties of the boundary of wall rock, the dissolving process in the interior of rock-salt cavern has been changed; so that the variation for the shape of rock-salt cavern has occurred. According to the mechanism of washing process of rock-salt cavern under coupled mechanical-dissolving effect, the computing method of washing process of rock-salt cavern under coupled mechanical-dissolving effect has been built. Based on the established computing method, by computing program of rock-salt cavern shape under coupled mechanical-dissolving effect and FLAC software the washing process of rock-salt cavern has been computed. the computing results show that compared with the computing shape of rock-salt cavern under dissolving effect, the computing shape of rock-salt cavern under mechanical-dissolving effect more coincided with the actual shape of rock-salt cavern. The results can provide a foundation for further analysis of the mechanism of washing process of rock-salt cavern.

The splitting sandstone from Yichang is taken as the research object. The authors make a study of the seepage velocity variation rules caused by different loading paths, axial compressions, confining pressures, particle diameters of filler and filler thickness, when the splitting sandstones are respectively filled by medium-fine sand, coarse sand and mixed sand. The rsearch results show that under different fillers and a certain stress, the seepage velocity changes with the loading path, which is one of the reasons for discreteness of seepage data measured in projects. The axial compression and seepage velocity are in linear relation; while the low confining pressure has a greater impact on the seepage velocity, but the high confining pressure has smaller effect. The particle size is positively correlated with the seepage velocity; and confining pressure has a larger influence on the non-filler sandstone than on the filled one. The seepage velocity and the filler thickness are in an increasing exponentially relationship within a certain range. The research also gives a quantitative analysis formula of axial compression, confining pressure and the seepage velocity in specified conditions.

For researching seismic response and piles’ bending moment distribution regularity of the slope reinforced by cantilever stabilizing pile, some seismic response model experiments of slope reinforced by cantilever stabilizing pile were carried out by using large-scale shaking table in Beijing University of Technology’s Structures Laboratory. During the experiments, inputted earthquake motion of Chonghua town, recorded the time course of changes of the acceleration of the slope at different positions and made comparative analysis and collected strain of the pile so as to analyze the bending moment distribution of the pile. The results show that: in the process of earthquake, the slope acceleration enlarged from the bottom to the top; and the enlarged effect of slope top achieved maximum. The reinforcement effect and the soil arching effect of cantilever stabilizing pile restrict the dynamic response of the soil near the pile. The strain of the interface between the mounted side and the cantilever part of the pile increases rapidly as the input of seismic wave; the strain of the cantilever part decreases with the increase in height; those reflect the convex distribution regularity of the bending moment of the cantilever sliding pile.

A series of laboratory tests was conducted for investigating the swelling deformation characteristics after one-dimensional consolidation under different vertical pressures and the nonlinear strength properties after dry-wet cycles for remolded expansive soil/rock specimens, which were derived from the field test section in Nanyang and Xinxiang, where the Middle Line of Water Transfer Project from South to North China passes. The test results indicate that: (1) With the increment of vertical pressure, the shear strength of expansive soil obviously has two stages characteristics, that is to say, there is great difference between the strength parameters under low stress state and those under high stress state. (2) Under the same vertical pressure, swelling ratio of expansive soil decreases linearly with increment of original water content; while increases linearly with increment of original dry density. Swelling ratio expressions which simultaneously reflect the influences of original water content and vertical pressure, and the influences of original dry density and vertical pressure as well are presented, respectively. Moreover, a stress-strain relationship for soaking after one-dimensional consolidation is also presented. On the base of analysis, some suggestions are provided for expansive soil slope: (1) There are often shallow slides for slope of expansive soil, so strength parameters under low stress state should be measured and applied to its slope stability analysis. (2) High compaction degree for the shallow area of slope and toe of slope is inappropriate.

The deterioration of ancient earthen monuments are highly related to the change in soil moisture content, so there is a practical need to find a way to measure accurately and easily the moisture content at heritage site.This paper reports the test results of soil water content measured by microwave drying method (MDM) compared with the standard method, the oven drying method (ODM), using soil samples including earthen monuments, saline soil and loess soil. The origin of test error by MDM is analyzed based on liquid limit test, plastic limit test, salt content test results. It has been found that the error of soil moisture content measured by MDM is increased with the increase in soil plasiticity compared with that measured by ODM; but the maximium error is restricted within 2%, satisfying the requrement of national code. Soil salt content is responsible for increasing the drying rate of the soil in MDM, but has no effect on the final masurement of soil moisture content. As a final conclusion, this research indicates that the MDM is a reliable method for soil moisture measurement in heritage conservation for its advantages of accuracy, speediness and convinence.

The block set mechanism was used to analyze the characters of pull-out capacity and failure surface of anchor plates. An application to upper bound analysis of vertically loaded strip anchors on horizontal ground surface is given first to illustrate the utility and effectiveness of the proposed method，and include detailed comparisons with model test results of Das[1] and Rowe[2]. Then analyses of anchor plates were given with emphasis on consideration of sloped ground. Comparisons between theoretical predictions of block set mechanism and model test results of Khing et al[3] and Rao and Prasad[4] are presented. The results show that the steel rod which adopted in model test as a loading device has a significant effect on pull-out capacity of anchor plates. So the Trapdoor model should be given priority in the model test of anchor plate which the sloped ground was taken into consideration.

Suoertou landslide which originated in fault rupture zone is a super large landslide, the sliding zone soil of the landslide consists primarily of highly weathered phyllite and slate in the Middle-Upper Silurian. There is about 30% amount of coarse particles of which size is greater than 2 mm in sliding zone soil; so the coarse particles occupy an important position in the soil particle composition and have serious influence on the stability of the landslide. The large scale direct shear apparatus is used here to investigate the direct shear strength behavior of the sliding zone soil under different moisture contents. The results show that there is a strain-hardening feature in the curve of the relationship between shear stress and shear strain with different water contents when the controlled dry density equals 1.7 g/cm3; besides, the more is the normal stress, the more is the hardening feature. The shear modulus G0.1 which is the modulus when the horizontal shear strain is 10% increases with the increment of normal stress at the same moisture content, and the shear modulus has a negative linear relation with moisture content at the same normal stress. The relationship between shear stress and horizontal shear strain can be simulated well by using Duncan-Chang hyperbolic model; but it can't reflect the strain softening feature of the sliding zone soil.

The dynamic response of slopes under earthquake is the basis of slope dynamic stability research. A dynamic numerical simulation model of bedding rock slope with bolts was established by using FLAC3D program; the dynamic response under coupling vertical and horizontal seismic waves is studied. The result of numerical simulation shows that the coupling vertical and horizontal seismic waves are closer to the actual situation and make greater destruction of the rock mass. Amplifications in the vertical zoom and free surface exist in bedding rock slope under coupling effects of earthquake. With elevation increasing, the horizontal and vertical accelerations of slope increase, particularly at the structural surface. Master factors of slope body early slump destruction are horizontal and vertical crack generated by vertical seismic waves. Amplification effect of parameters in slope dynamic response shows that the amplification coefficient of vertical acceleration is larger than that of horizontal acceleration; and the vertical and horizontal velocity decreasing one by one. With the increasing of aV/aH under coupling effects of earthquake, the horizontal displacement of monitoring points increase and it proves that the vertical seismic action plays an important role in the destruction.

The soil-water characteristic curves in three dry densities are obtained with filter paper method; the parameters of Van Genuchten model are received by fitting test data; and the influence of dry density on soil-water characteristic curve and parameters of Van Genuchten model is analyzed. The effects of compactness and water content on resilient modulus are analyzed with laboratory test of resilient modulus; and the relationship between them is established. At last, based on hydromechanical coupling mechanism and combined with the test results, the dynamic response model of subgrade moisture and deformation under the variation of groundwater level is built; the distribution of water content and resilient modulus and the deformation of subgrade are calculated when the groundwater level rising from -6 m to -3 m. The results show that: dry density has great influence on parameters of Van Genuchten model of soil-water characteristic curve, the saturated water content linearly decreases, the residual water content and parameter n linearly increase with the increase of dry density; and the parameter has a linear correlation with the reciprocal of air entry value; the resilient modulus decreases with the increase of water content and increases with the increase of compactness. The water content increases and resilient modulus decreases significantly caused by the rise of groundwater level; then it results in unnegligible deformation of subgrade. Under different filling compactness, the difference of deformation of subgrade caused by variation of groundwater level is obvious. Therefore, controlling compactness is an effective method to improve the performance of subgrade.

Based on the method of images, the three-dimensional soil loss additional load formula caused by DOT shield tunneling soil loss is derived by using non-uniform soil movement model. The distribution regularity of total additive load from additive thrust force, the friction between DOT shield machine and soil together with soil loss on existed adjacent tunnel is researched. The results show that: the distribution regularity of additive load is closely related with the relative position of existed adjacent tunnel and DOT shield tunnel; and it is a three-dimensional problem. In the thrust direction, the additive stress changes from tension behind into pression ahead of the excavation face. Soil loss is the main factor in total additional load, followed by friction and thrust additional force; the additional load that the existed adjacent tunnel subjected to is closely related to its net spacing away from DOT shield machine S; and additional load increases rapidly when S decreases; the existed adjacent tunnel is subjected to the greatest additional load in the axis position of DOT shield machine with the variation of axis buried depth of the existed adjacent tunnel.

A systematic study of foreign standards, is the first step and key problem for the enterprise to go abroad to overseas market, and to enhance the international competitiveness. On the other hand, the revision and perfection of current domestic codes must draw lessons and absorb the advanced experiences from international standards. The basic principle of the European geotechnical engineering design code[1] including the action, effect, resistance and limit state calculation inequality, taking value characteristic of partial factors and application situation for three design approaches are introduced. Taking “The code for design of building foundation”[2] for example, the comparative analysis is made to find the similarities and differences in design approaches of the Chinese and European geotechnical design codes and the problems in domestic standards. Finally, a shallow foundation design example is given to illustrate the computing errors among three kinds of design approaches of European standard and those of domestic design codes. On this basis, the suggestions for improvement of domestic design codes are put forward.

A series of calculated curves for computing the safety factor of 3D soil slopes are presented here, in light of the analysis process of the 3D limit equilibrium solution to the slope stability is too complex to be widely used. The safety factors of 36864 homogeneous slopes were calculated in advance by using the 3D limit equilibrium solution with a simplified 3D slip surface. And a series of calculated curves were obtained based on these calculation results. According to the curves, the safety factor can be quickly obtained, which is more accurate and reasonable than the 2D analysis. And also the soil strength parameters of the slip surface can be got by back analysis, which overcome the disadvantage that the soil strength parameters obtained by 2D analysis are higher than practical values. The study provides a simple and practical method to the 3D slope stability analysis.

Due to the importance of study of mechanical parameters of rock mass discontinuities, four shear strength parameters linear regression methods, i.e. least square method, point center method, random-fuzzy method and reliability method, were carried out to conduct the comparison and theoretical analysis. An improved algorithm with rigorous solving process and higher calculation accuracy was proposed based on the traditional point center method. The optimized mean and standard deviation assignment method of shear strength parameters c, of rock mass discontinuities was presented to ensure the accuracy of initial assigned parameter with JC method based on reliability theory. An example of Jiweishan landslide in Wulong County was taken to explain the applicability of the above four methods under different data conditions of rock discontinuities. The result indicates that the applicability of four methods depends on the divergence and volume of the data. Each method of the four can be directly applied for the linear regression analysis of the shear strength parameters of rock discontinuities when the data is under good linear relationship. However, the point center method is not available anymore when the data is discrete; and the reasonable method should be determined according to the engineering requirements, exceptional value and convergence conditions.

Rock mass is a rheological material; under the action of high geostress for a long time, its inner unequal stress could relax as time itself; thus finally tends to be hydrostatic stress state. In such state, although the volume remains elastic, it lost the ability to resist shear deformation; its energy mostly stored in volume deformation. This paper uses a plane compression model to investigate the deformation behavior and energy distribution relationship for rock mass under different stress levels long-term effects; and then discusses the brittle fracture failure for strong unloading, so as to reveal the influence law that initial geostress value(energy distribution relationship) acts on rock mass deformation(inertia, viscosity and elasticplastic deformation). The research results build a basis to establish the loading-unloading constitutive model for deep rock mass.

Taking the Xikema no.1 tunnel as engineering background, the reinforcement effect of pre-reinforcement measures including pipe-roof and double-row small duct, is studied through the model test. Some useful conclusions are drawn by analyzing the change law of stress and displacement of surrounding rock in different pre-reinforcement measures during the excavation, The research results show that: (1) In the tunnel longitudinal direction, pipe-roof and double-row small duct play a role of supporting beams; they can primely control the above surrounding rock loose caused by tunnel excavation and reduce surrounding rock stress above the work face, so as to guarantee the stabilization of the work face. (2) In the tunnel on the transverse, pipe-roof and double-row small duct can form into a complex well with surrounding rock, which plays a role of load-bearing arch to limit the above surrounding rock stress release and improve the safety of the supporting structure. (3) The longitudinal beam effect of pipe-roof is stronger than double-row small duct; but the transverse arch effect is weaker than double-row small duct.

It is significant for the reliability assessment of retaining wall to analyze the displacement and earth pressure induced by earthquake. Based on the pseudo dynamic method, a new model is proposed to compute the active earth pressure. The proposed model considers time effects, phase difference of wave spread, overload friction on the back of retaining wall, cohesion and internal frictional angle of backfill soil. Then, the active earth pressure, distribution pattern and height of action point are obtained. Meanwhile, taking the seismic response of retaining wall, the rotational displacement about the toe of retaining wall is determined. Comparison between the Mononobe-Okabe method and present model is carried out. The results show that the active earth pressure obtained by present model is similar to the Mononobe-Okabe method. But the height of action point obtained by Mononobe-Okabe method is lower than present model; this revealed that seismic engineering design by using Mononobe-Okabe method may be led to risk. Finally, the dependence of the rotational displacement of retaining wall on the seismic coefficients, friction on the back of retaining wall, surcharge, time effect, cohesion and internal friction angle of backfill soil are discussed by case studies.

Based on theoretical analysis of specific power of broken hard rock, a mode of specific power of broken hard rock has been established. Tools structural dimensions and rock mechanical performance and broken technique three types parameters, which are interrelated with specific power of broken rock, have been determined. Fuzzy logic method (FLM) has been introduced to predict the specific power of broken rock. Taking the above three types parameters for input variables of FLM and the specific power of broken rock for output variables of FLM, a fuzzy prediction model of the specific power of broken rock has been established. The model is applied to a project instance. The comparison of the project practice real value and the model value shows that the model values are close to the project practice real values. It is indicates that the model is reasonable and fuzzy if-then rules can express the experience of the project practice. Given input variables, the model can predict effectively specific power of broken rock.

Relationships between the difference of 2D and 3D safety factor and parameters of landslide geometry (including ratio of slope, 3D sliding mass shape and length of landslide) and soil strength (including cohesion and internal friction angle) are studied. 2D and 3D safety factor of the different parameters homogeneous slopes are calculated based on the slope stability analysis program of the limit equilibrium method by modifying normal stress over slip surface. The ratio of 3D to 2D safety factor (denoted by F3/F2) is used to analyze the difference of 2D and 3D safety factor. Then, variation rule and mechanism of F3/F2 by changing parameters of landslide geometry and soil strength are also discussed. Finally, the standard of ignoring the difference of 2D and 3D safety factor are proposed from the view point of engineering practice. Results show that: F3/F2 decreases while ratio of length to height, internal friction angle and ratio of slope increases, and increases when cohesion increases; 3D safety factor is suggested to estimate the slope stability when (1) ratio of length to height is lower than or equivalent to 5; (2) ratio of length to height is more than 5 and lower than or equivalent to 10 while cohesion more than 25 kPa or internal friction angle lower than 15° or ratio of slope lower than 1. The conclusion can be referring to correct evaluation of slope stability.

Prebored hole is an effective construction measure for reducing the squeezing effect of sinking-pile. For the problem of soil squeezing by sinking-pile adjacent to slope, it is assumed that the soil is the linear elastic constitutive model, The process of sinking-pile is simulated by a series of continuous spherical cavity expansion, Based on the mirror image method and present literatures, the soil squeezing displacement expression caused by pile sinking adjacent to slope is deduced which considers the influence of prebored hole. The results show that the soil compacting effects which far away from the hypotenuse free boundary side are not as obvious as the opposite side due to the influence of asymmetrical displacement boundary; the compacting effects become more obvious with the steeper of the hypotenuse free boundary; the influence of inclination boundary to the soil squeezing displacement would be gradually smaller with the increase of free inclination boundary angle; the aperture and hole-depth are important factors for the compacting effects of pile sinking adjacent to slope; combination of the aperture and hole-depth can effectively reduce the compacting effects. The results provide some reference value for engineering design.

The definition of effective pile length can be concentrated on bearing capacity or on pile head settlement. The study of effective pile length is still in progress because of the various affecting factors. The method of controlling the pile head stiffness is used to determine the effective pile length. Based on the Winkler model and load transfer method, the formula of pile head stiffness in two-layer soil is deduced; and then some affecting factors of effective pile length are analyzed The effective pile length increases with the increase of pile diameter; and decreases with the increase of the soil stiffness ratio (defined as the stiffness of the second soil layer to that of the first soil layer). The increase of pile base stiffness doesn’t play an obvious role in effective pile length. The effective pile length will be increased when the thickness of the first layer increase within a certain range.

Compression modulus of soil layer is a very important parameter for settlement calculation about bridge pile foundation in thick soft clay. According to bridge pile foundation subside of Beijing-Shanghai High-speed Railway, calculation formula for compression modulus related soil depth of soil layer in natural state are obtained by fitting analysis based on data of geotechnical test and the achievement of in-situ test in construction site DK152. On this basis, the finite elements calculation is done; and settlement of pile foundation is in good agreement with displacements of field monitoring. Using neural network, the mapping relation between settlement of pile foundation and compression modulus of soil layer is established. By back analysis of compression modulus of different soil layers and different depths, correlation inversion results are basically identical with calculated values by empirical formula; it is shown that calculation formula for compression modulus proposed in this paper is practicable and accurate; and model generalization and the inverse calculation method are reasonable. This study has certain reference value for settlement calculation of long pile foundation of high-speed railway bridges on deep soft soil.

The working pattern of single pile embedded in expansive soil will be influenced by the soil’s water content directly. In order to study how the soil influencing pile when it is soaking with water, the prototype test of expansive force of bored pile is carried out. The test result shows that the vertical displacement of soil increases slowly and to be stable finally. Influenced by soil water content and compactness, the vertical displacement of shallow area is always greater than that in depth. During the soil expansive process, the uplift force of pile top increases rapidly and then increases slowly; and at last to be stable. According to mechanical analysis of pile and test results, the expansive force is a comprehensive representation parameter of expansive shear force, pile weight and pile-soil interface friction. For more safety, pile length should be long enough to make sure the anchoring force of pile is larger than ultimate expansive force.

Penetration process of projectile penetration high strength concrete target with different penetrating angles is captured in the light gas gun by using the high-speed photography. And the motion feature of projectile affected by the penetrating angle and penetrating velocity is analyzed. The result shows that projectile has a horizontal movement as the striking angle is 0 degree, while it deflected after 150-200 μs as the striking angle of target more than 0 degree and the projectile in a lower penetration velocity around 200 m/s. There is a positive correlation between the level penetrating velocity, deflection angle and its time. The penetrating time of projectile in horizontal movement and the spatter velocity decreased mainly affected by the decrease of penetrating velocity of projectile at a certain penetrating angle. The influence of penetrating angle on spatter velocity and projectile horizontal penetration time is relatively larger than that of the penetrating velocity of projectile. It is proved that the size of penetrating angle is important and unavoidable in security protection fornications.

The monitoring of bolt strain in the model test is relatively difficult for its small size. To solve the problem, the optical fiber Bragg grating sensing technology is applied to the tunnel model test. By constructing tunnel model test based on the actual working conditions of four typical sections in the metro line 2 in Xi’an, the strain of bolts in different stress states can be monitored by the fiber Bragg grating (FBG) sensors sticked to the bolt surface which are packaged by own design. According to the recorded data of five stress states: before the tunnel excavation, after the tunnel excavation, after lining, crack limit state, destruction limit state, the change law in the loading process of anchors axial force in the tunnel is obtained. Test results show that the anchor force has certain change before and after the excavation.After lining the axial force of anchor is increased with the increase of rock pressure. After lining the bolt pressure near the vault begin to decrease, the bolt tension from spandrel to corner begin to increase; the axial force of bolts in the larger water content loess is higher than in smaller ones. It is shown that the method presented provides a new and reliable approach for monitoring bolt strain in the model test.

When material bearing explosive dynamics load is in failure state, it has the shear dilatancy behaviors, at the same time, the material structure and the elastic wave velocity are changed. The material volume strain and the velocity near explosive cavity are measured using strain gauge embedded in model body and acceleration sensor. Measuring results show that, in the model test, the similar failure rock zone area as reality under the explosion circumstance is obtained; the measuring methods are effective and reasonable, when it is used to monitor failure area in explosive model test and it can provide experimental basis for related analysis.

The beam on elastic foundation model is used to simulate the underground tunnels structures; a vibration equation on two-parameter foundation considering the bending moment, axial force, shear deformation, external and internal damping is obtained. An approximate method for calculating of displacement of underground pipes is used to compute the displacement of underground tunnels structures, avoiding the trouble of integral transform. In numerical example involving the damping. it is convenient to use a special separated variable method to obtain natural frequencies and damping ratio, the attenuation of displacement considering damping. It is concluded that for underground structures, the effect of internal damping can be neglected.

According to Hoek-Brown failure criterion and equivalent-area principle, strength parameters of engineering rock masses can be estimated by data from lab test and field geological survey. These parameters are naturally applied to engineering classification of rock masses. In terms of deep-buried engineering, this classification practically reflects local environment and mechanical states of rock even better than traditional BQ classification.

There is strong vertical heterogeneity in sandy conglomerate reservoir. In this paper, based on typical layered sandy conglomerate image, representative core slices of different layers are chosen and the corresponding digital rocks are reconstructed respectively. Then, mergence method is developed to construct the sandy conglomerate digital rock core and the corresponding pore network model is extracted. Meanwhile, traditional method is used to construct the corresponding pore network model. At last, the structures and permeability characteristics of sandy conglomerate pore network models obtained from above two methods are compared and analyzed. The results show that the sandy conglomerate pore network model with mergence method could effectively describe the pore structure characteristics; and it also can describe the horizontal and vertical permeability differences effectively, so as to provide an effective way for the rock core characterization and flow mechanism analysis in sandy conglomerate reservoir.

The high cost of handling and the potential reuses of waste foundry sands made the research on waste foundry sands reuse to be attached importance, which is especially beneficial to the improved soil for roadbed. A laboratory testing program was conducted on waste foundry sand and expansive soil-foundry sand mixtures to assess their applicability as improver aimed at the swell-shrink characteristics of the roadbed. The mixtures were compacted in the laboratory at a variety of moisture contents and waste foundry sand content; and the basic physical properties, compaction properties, and mechanical properties were analyzed. The results of the study show that the strength of the mixture is highly dependent on the waste foundry sand content and water content at compaction. Along with increasing waste foundry sand content, plastic index and optimum moisture content gradually decreased; the marginal increment of maximum dry density changed little; and the unconfined compression strength increased at first, then decreased.

Many faults propagate near the underground powerhouse of Dagangshan power station. Rockmass stability of the underground powerhouse is controlled by two steep angle faults which are extended through the middle and rear parts of the powerhouse. The collapse area near the fault was found when the fault extended through the vault was excavated. So it is necessary to monitor the stability of the powerhouse and collapse area near the faults. The integrated seismic system(ISS) of South Africa is established to monitor the area in October 2010. The unattended system run automatically, which also can be controlled and diagnosed remotely. Four methods such as spatiotemporal distribution method, magnitude level method, energy index method and dislocation method are used to analyze the stability of the collapse area, side walls and the rock mass near the structure plane. The research results show that the underground plant is overall stable and safe. Few seismic events and low magnitude near the collapse area can be got from seismic monitoring data. Two side walls are stable because the number of the seismic events and dislocation slip of the rock mass are small. The slide displacement between the structural planes is scattered and small. And the rock of the fault plane is inactive. Therefore, the stability of collapse area is increased and less influenced by faults after the rock is reinforced by the anchor. It is of guide significance to use microseismic monitoring to assess the stability of power house during the running and construction stages.

Squeezing effects of different piles are hot issues and important problems in engineering design and constructions. Based on the Fourth Yangtze River Bridge?s north-line soft soil treatment engineering at Nanjing, the squeezing effects of X-section cast-in-place concrete pile (referred to as XCC pile) were studied. The influence of pile construction on pore water pressure changes, earth pressure and lateral displacement are observed by pre-laying piezometers, earth pressure cells and inclinometers, respectively. Instruments are embedded at different directions and different depths. Through analyzing the data from field tests, the squeezing effects of XCC pile are obtained. The results show that the maximum horizontal displacement occurs at the top of the piles; and these displacements can be neglected when the distance exceeds five times of equivalent pile diameter. It is also shown that crowded soil pressure and pore-water pressure decreased with the increasing of center distance; besides, pressure of sharp corner is larger than that of concavity. The data from field tests provide other engineers with reliable evidences.

Core disking is one of indicators of elevated geostress magnitude. The shape of disked cores is directly subjected to values and directions of three principal stresses. In the case of drilling-induced core disking, 3D geostress states cannot be measured by usual overcoring methods. Based on the previous studies of core disking, we provide a convenient substituted measurement of 3D geostresses by determining the geometry of disked core’s surface. Practically, the directions of three principal stresses from our method are quite close to those from other measurement in the vicinal site. The differences of inclination are in the range of 10°; and those of azimuth less than 20°. Moreover, the magnitudes of principal stresses satisfy the well-known condition to cause core disking.

Based on the fact that Jiangmen Tunnel of Guangzhou-Zhuhai Railway under water-rich channel has characters of super-shallow, large cross-section and water-rich, this paper aims to propose a systematic analysis of the risks of the super-shallow tunnel with large cross-section under water-rich channel and to elaborate reasons for these risks and their potential detriments. After the initial comparison of possible pre-reinforcement means and excavation schemes, a quantitative comparison and selection is further conducted by using three-dimensional numerical simulation approach. It suggests that with the precondition of taking surface water-resisting measures, the excavation scheme in the combination of horizontal jet-grouting and large pipe roof advanced support and 3-bench method should be applied. As is suggested in the research, this scheme is not only effective to waterproof and reinforcing the stratum, but also has its advantages to eliminate the risks of collapse, accelerate the construction progress and reduce the cost at the same time on the prerequisite of ensuring the safety of tunnel construction, so as to provide some references for other similar projects.

The excavation height of left slopes at Jinping I hydropower station is 530 m; faults and deep fracture were developed, unloading range is deep; and its geological conditions is complicated. Slope stability problems are important especially in the construction and operation. The engineering monitoring geological conditions of the slope is analyzed; deformation monitoring layout for the slope is described. The deformation monitoring system of the slope consists of surface deformation observation, shallow deformation observation and deep deformation observation. In three levels, monitorings of the slope deformation are made. For the surface deformation monitoring the geodetical surveying method is used; for the shallow deformation observation the multi-point displacement meters are used; the monitoring depth is 0-90 m; for the deep deformation observation the flat hole ranging, level survey and graphite convergence meters methods, etc, are used installed in exploration flat hole, through the main fault and deep crack, the biggest monitoring depth reach 260 m. By May 2011, monitoring data indicate that the maximum horizontal displacement in surface and shallow is 106.1 mm; the maximum settlement is 58.6 mm; which are controlled by excavation and supporting; the maximum horizontal displacement in deep is 47.48 mm; the maximum settlement is 7.2 mm, controlled by faults and deep fractures. The displacement tends to converge, the maximum deformation rate is 0.1 mm/d; and it meets the designed safety standards, slope has verged to stable.

The stability analysis for a typical tailings dam is carried out by combining the fluid-solid coupling method with the strength reduction method. Then the seepage field, the location of potential sliding surface and the safety factor are determined; and the tailings dam failure criterion in strength reduction method for tailings dam is suggested. By comparison, the location of the saturation line by the above determined seepage field is in accordance with the field measured saturation line; meanwhile, the location of the potential sliding surface and the safety factor is well consistent with the results by Bishop method, so as to show the feasibility of the stability analysis for the tailings dam by combining the fluid-solid coupling method with the strength reduction method. Based on the above results, the instability model of the tailings dam is studied; and two instability models are concluded, one is the local instability which the instability takes place in the part of the tailings dam sliding; and the other is global instability which can cause the whole tailings dam failure. Moreover the main factors which lead to the two failure models are analyzed; and the result shows the important factor of the local instability is caused by the too shallow saturation line in the tailing dams.

The 2×2 lane Yuzhou Tunnel was extended to 4×4 lane tunnel in Chongqing airport road. Taking this project as an engineering background, the influences of in situ extension of the tunnel excavation on adjacent buildings and blasting effect on adjacent buildings are studied. The main study methods include the literature research, numerical analysis, monitoring measurement and blasting monitoring. The main conclusions are drawn as follows. (1) Unilateral expansion, both sides extension and around extension are the three tunnel extension method in situ, by construction mechanics analysis, the unilateral extension is optimal; (2) maximum surface settlement curves of extension tunnel are similar with neighborhood tunnel; (3) radius of surface settlement trough curve is about 40 m; (4) the max surface settlement differential is about 10 m and 30 m distance from the center line. The building settlement meets the specifications, and the buildings are safe; (5) blasting vibration monitoring data indicate that the vibration speed of the near building and tunnel is below the specification limit, which indicates that the free face of the existing tunnel absorbs and releases most of blasting vibration energy. The research results provide a reference for similar tunnels in situ extension project.

The surrounding rock controlling technology of large cross-section coal roadways under high stress in tectonic region is one of the problems to be desiderated to solve in coal mines. Aiming at the large deformation of the typical complex coal roadway in Xinsan coal mine of Fengfeng Company, in combination with the field observation and numerical simulation analysis integrated the results of large-section coal roadway under high stress deformation and failure characteristics, and then a type of surrounding rock controlling system called high strength bolt and cable truss is proposed on the basis of the core structure “cable and arch”. The basic structure, design process and prestress distribution characters of roof strata with the controlling system are analyzed. A field test is done on replacement coal roadway for filling waste gangue. Research results show that supporting structures of the new style system are stable; and the surrounding rock of the roadway is controlled well, which has theoretical and practical value to the supporting technology of analogous complex roadways.

Currently there are many tunnels through the slate formation, slate tunnel engineering problems are frequently occur due to the unique nature of slate, and collapse phenomenon is a large part of the engineering problems . The feature and influence factors of slate tunnel are studied by the analyzing the collapse phenomenon of Muzhailing tunnel, then the board stability theory is used in the collapse mechanism of slate, and combine the engineering practice with board stability theory subsequently. Finally, the key methods to prevent collapse phenomenon are showed, and the method is used in the subsequent engineering. The results show that the slate layered characteristics and slowly construction of initial support is the fundamental factors in the collapse occurred, preventing the collapse phenomenon need to study primarily from these two points. The subsequent sections of Muzhailing tunnel are constructed safely; it’s proved that collapse causes of slate tunnel are well analyzed. That is useful to the similar engineering when they want to prevent or deal with the collapse of slate tunnel.

The cantilever and tension crack-type collapses, which often occurred in steep rock slopes with nearly horizontal layered stratum, are very common in nature. This kind of perilous rock mass is not only much in quantity but also high in frequency of occurrence in mountainous areas of southwest and northwest China and Three Gorges area in China. The research shows some exogenic geological processes such as differential weathering, river erosion, seawater abrasion and carbonate dissolution can cause rock cavities and cantilevers on the surface of rock slopes. On the basis of field investigation, two kinds of failure modes for cantilever and tension crack-type collapse have been established. The two different failure modes are thick hard rock inter-bedded by thin weak layer and thin hard rock inter-bedded by weak layer respectively. According to the calculation theory of maximum bending stress for cantilever beam, the formulas of limit depth for rock cavity has been derived; and moreover, the time of failure of a collapse has been predicted using the rate of weather denudation for limestone. Analysis results show that the limit depth of rock cavity is positively correlated with the thickness of cantilever and negatively correlated with the depth of tension crack on the top of slope. According to the method of ratio of maximum tensile stress to tensile strength, a formula of safety factor has been deduced. Furthermore, the evaluation criteria for cantilever and tension crack-type collapses are given. Finally, the new method is verified by a typical case study; and the results show that some features such as concise formula and reliable calculation are obvious in the actual project application.

The Dagangshan hydropower station dam abutment slope stability has been studied based on the theory of unloading rock mass. Based on the large-scale universal finite element program ADINA, for the conditions of different earthquake accelerations, different anchoring lengths and tonnages of unloading dam abutment slope, the displacements of key points, stresses and plastic zones change rule are comparatively analyzed; and it is pointed out that the slope deformations are composed of two parts; one part is unloading rebound, the other part is the compressive deformation of inner facing slope induced by applying large tonnage anchors. Research shows that because of the cable through the V-shaped rock bottom line, in the possible shear zone of landslide there formed a strong resistance sliding key, so that increasing cable length or tonnage can effectively reduce the plastic zone of the abutment; for accelerations of 0.1g and 0.15g in the earthquake, in different reinforcements of tonnages, may form transfixion of plastic zone. Under different earthquake accelerations effected by different anchorage length and anchoring force, the horizontal displacements of different key points presented linearly and nonlinearly changing; inflection point in the nonlinear relationship should be paid attention to. To reduce the plastic zone of rock mass, it is better to increase anchorage length in the same proportion. In order to effectively reduce the plastic zone development during strong earthquake, the 120% increase in anchor length is suggested.

For the engineering background of a typical subway tunnel with initial defects caused by the construction of the new down-through tunnels in Beijing, the aseismatic performance of the existed tunnel is studied so as to reveal the mechanism of seismic dynamic response by using finite difference method. Numerical model will firstly be established. Then its boundary conditions and initial conditions are considered, including the choice of related parameters and seismic wave at the same time. The numerical simulation results show that the tunnel is deforming in its entirety since such physical variables as displacement and stress in its all key weak points have the same dynamic tendency under the influence of approaching construction of tunnels, and the variables including displacement and stress are much larger than those without any influence. For examples, after down-through construction, much influences of aseismatic performance are mainly taking place at both the side wall and the upper arch; and the shearing damage are mainly doing in surrounding soil mass. Due to widely shearing damage after down-through construction, it is suggested that grouting reinforcing should be applied so as to make them much stiffness as a whole and to have good aseismatic performance.

The contradictory between the construction of metro station and shield tunnel may be high effectively and safely solved by enlarging shield tunnel with shallow buried and undercutting method. The experiment section of Beijing metro line 14 is constructed by earth pressure balance shield machine with an outer diameter of 10 m; and the stations on this section will be constructed by pile-beam-arch method. The empirical formulas of predicting the ground surface settlement, the related statistics data and specifications, and numerical simulation methods, are used to predict the ground surface settlement caused by the large cross-section shield tunnel combined with pile-beam-arch method in construction process. Combined with the ground surface settlement control reference value of Beijing metro station and the statistic data of existing metro station statistics, the reasonable ground settlement control standard is put forward. In accordance with the three class control management methods, the ground surface settlement is controlled step by step. The research result has some reference value to guide the engineering construction.

Due to its difficulty in mathematical method for boundary conditions, analytical method for soil deformation induced by shield tunneling subject to certain restrictions in the practical engineering. In order to solve this problem, Airy function in elastic mechanics is introduced to put stress and displacement distribution into analytic function in the infinite half plane. And the boundary collocation method is adopted to determine stress boundary conditions in the ground surface ( = 0， = 0) and displacement boundary conditions around tunnel ( ， ). Stress and displacement function’s coefficients can be obtained by the least square method. And the semi-numerical and semi-analytical solution could be deduced by putting the coefficients into the corresponding functions. As shown by calculation for a project case, this method can consider any boundary condition for stress and displacement, and make full use of advantages for both numerical method and analytical method. The results are consistent with the observations. So there are practical values in predicting surface settlement and deep soil deformation, so as to provide a theoretical basis for controlling soil deformation.

Environmental vibration pollution caused by city rail transit can’t be ignored. By means of in-situ test and theoretical analysis, the attenuation discipline of amplitude and frequency of ground vertical vibration acceleration with distance from track center line by Nanjing rail transit operation on ground has been obtained. With the horizontal distance between the test point and rail transit track increasing, the amplitude value of ground vertical vibration acceleration fades as a whole, but rebounds slightly at 20 to 30 m off track center line. Meanwhile the frequency of ground vertical vibration acceleration ranges from 0 to 100 Hz, and the dominant one is in the range of 30 to 80 Hz. With the distance from track center line increasing, the vibration signal component of each frequency also shows a fading tendency as a whole, and decays faster at the higher frequency. In view of Beijing Jiaotong University forecasting formula, a prediction model of ground vibration caused by Nanjing rail transit operation including the parameters of receiving point distance, the property of foundation soil and train speed has been constructed, and forecasts well compared with the actual measured data.

Tunnel fire accidents can lead to the damage of inner structure and the degradation of mechanical properties of lining materials; and then cause the increase of deformation of tunnel linings which are danger to the safety of tunnel structures. Based on the theory of geometric and material nonlinearity, a theoretical analysis model of linings deformation of tunnel subjected to fire load is presented. In the model, the influences of thermal damage and thermal expansion are taken into account. In a example, the analytical solution of cross-section slope and radial deflection of tunnel lining subjected to fire load is presented. The influence of fire duration on the deformation of lining is analysed, which can provide the theory basis to practice engineering.

With the rapid development of the construction of rail transport, the vibration caused by the operation of rail transport is causing an increasingly concern. In order to study the characteristics of ground vibration load and its law of propagation, we set the rails, sleepers, ballast bed and roadbed above the ground as a whole according to the structure of the train and characteristics of the structure of ballast bed, and build a two-line spring model consisting of a car-bogies-ballast bed structures to calculate the ground vibration load. By analyzing the test data about the velocity of ground vibration and the vibration of the train itself, we can get the number expressions of the ground vibration load by using fast Fourier transform (FFT) program to analyze the ground vibration load data for Fourier transform.

Rock is treated as a compound including three component parts: grain, interface and matrix. FLAC is used to model the distribution and evolution of the shear strain increment, the minor and maximum principal stresses in the surrounding rock after a circular tunnel is excavated. Results show that in hydrostatic pressure, higher shear strain increments are mainly distributed in the soft matrix, forming an intersecting shear band network. However, higher minor principal (loop higher compressive) stresses are found at grains, generating several annular or ring regions. Larger granular sizes lead to fewer and longer shear bands, less number of regions with higher minor principal stresses and larger spacing between them. When the lateral confining pressure coefficient is not 1, the envelope of the shear band network exhibits two triangles at two opposite sides of the tunnel. At larger granular sizes, the results are similar to the zonal disintegration phenomenon in the tunnel surrounding rock at depth. Thus, a possible mechanism is proposed for the phenomenon. In jointed rock mass, several rock blocks are compressed together to form a ring in the loop direction of the surrounding rock due to the self-organization. If the stress level is high enough, several loop cracks isolated by zones without failures can be formed.

Many factors, experimental conditions and complex coupled relations need to be considered in the multifield coupling of geomaterial. Therefore, it is much important to study the thermo-hydro-mechanical(THM) coupling problems using numerical simulation method. According to the continuum theory of mixture, a coupled model and the governing equations of the coupled problem of temperature, seepage, and stress field for geotechnical media are deduced. Strategy and methods to solve this mathematical model also are discussed. Based on the software MATLAB, the program of THM analysis is coded, in which Abaqus is embedded as a module in the iterative algorithm. Through two typical examples, the proposed THM program is verified; and the results show that this method is a very good analytical method and its efficiency is very good. And then the code of THM coupling model is applied to simulate the construction process of petroleum drilling and analysis of wellbore stability. The evolution law of temperature, pore pressure and stress field in surrounding rock are obtained. And the variations of drilling fluid temperature have significant influences on wellbore stability. The study has significant effects on the design and construction for underground oil and nuclear waste disposal.

The valley stress field of Jinping I stage hydropower station is regressively computed based on investigating geological conditions. The in-situ test data and the calculation results that were explored by predecessors are considered and comparatives analysed during the regression simulation process. The geological section III is served as research object; and it is meticulously generalized; then a numerical model with complex geological structure is established. At the same time, the river development history is investigated. Then the evolution processes of bank slope frontier and weathering rock belt are designed based on the river cutting speed and timespan during every river terrace. Through many regression calculations, the stress trial method is chosen. Through analyzing Jinping tectonic characteristics, in-situ geostress data and predecessor’s results, the 12 MPa and 8 MPa uniform stress are decided to apply on model boundary after many trial computations. The regression simulation results are the best one, when the uniform stresses of 12 MPa, 8 MPa are applied on two vertical boundaries of the sixth river terrace model with the gravity stress field. A comparative analysis between the simulated results and the measured geostress data is carried out. It is shown that the magnitude and distribution depth of the stress concentration zone at the bottom are both fitting with a high precision between the calculation results and in-situ stress data. Through analyzing Jinping valley stress field features, it is shown that the stress distribution is not symmetric between left and right bank slopes. The stress distribution in the left bank is more complex due to the influence of fault and macular dikes tending to outward. In left bank the stress strong differentiation zone and unloading scope are both deeper than right bank.

According to the site measurements of geostress and engineering geological conditions in Ada dam area of west route of South-to-North water transfer project, the established 3D simplified geological model of the dam is calculated by FLAC3D combined with the linear multivariate regression analysis principle. Then, the optimum regression coefficients have been achieved. Comparing the computed results with the measured geostress data, it is found that the two are very close in values and directions, which suggests the accuracy and reasonability of the geostress field regression. Therefore, the distribution rule of the initial in-situ stress field can be obtained accurately. The further analysis is shown as follows: (1) The stress concentration at the bottom of the river valley is obvious; and the vertical depth of the zone is about 80 m with the peak value of 15 MPa. (2) There exists considerable difference between the maximum horizontal principal stress direction of two boreholes which are only 350 m apart, which reflects the control action of the direction of compressive principal stress by geographical and topographic features of the river valleys. (3) The initial geostress field in dam area is a medium stress field which is dominated by tectonic stress field at the shallow parts; but control action of gravity field increases gradually with the increment of buried depth. The results above provide important reference for design and construction of Ada dam and its diversion tunnel axis layout.

The underwater tunnels can be regarded as shallow tunnels. So the classical problem of an elastic half plane with a circular cavity, loaded arbitrarily on the horizontal boundary can be used to analyse the stress and displacement fields of the surrounding rock for underwater tunnels. As is known to all, it is much more difficult to deal with shallow tunnels than deep tunnels via the analytical way. Using Verruijt’s conformal mapping function, the region of exclusion of a hole in a half plane is tansfered into a cirque. Then the analytic functions can be expanded as Laurent series in this region. The stress and displacement can be solved by the function of complex varibles method founded by Muskhelishvili. The corresponding calculation program is coded by Fortran. As an example, a specific underwater tunnel is analysed by the Fortran calculation program eventually.

Regarding the typical engineering as the prototype, we utilize the FLAC3D finite difference software to build the model of a three-dimensional slope, and analyze the impact on slope dynamic response characteristics and dynamic instability mechanism which are influenced by stepped slope platform width. The results show that the slope platform can effectively improve the slope stability under seismic dynamic conditions; the slope with greater platform width will be more stable; and the PGA amplification factor decreases with the increase of platform width; moreover, the first step dynamic response of a slope on the top of the hill is more outstanding than the second step toe with the combination of spectrum analysis. The slope’s rock and soil shear strain increment and the displacement response is also reduced. Plastic zone of slope under earthquake develops from the toe area to inner slope increasing with the earthquake duration; at the same time hill will be tensile deformation; slope and shallow surface layer will be tensile shear deformation, and certain parts of the slope will present a shear deformation. Displacement curves of slope monitoring points show that slope toe displacement is upward under earthquake; and the cut deformatiobn will occur; the slope slope toe and the point of gradient change become weak parts; so it should be protected tightly. The results have a guiding significance to the seismic design of earth slopes.

In the tunnel construction process, the displacement monitoring data are usually used as the most important basis for identifying the stability of the surrounding rock, and sometimes even the only one. However, in the tunnel design process, no displacement criterion is established for identifying the stability of the surrounding rock, for the large differences among surrounding rocks with different lithology and geological environments. Furthermore, shape, span and burial depth of the tunnel would probably also effect the displacement of the surrounding rock. On the other hand, statistical analysis of the on-site displacement data indicate that under general conditions of surrounding rock, the relative displacement value of the same grade rock has obvious cohesion compared with obvious differences between the relative displacements values of the different grades. With this characteristic, an identifying rule of stability can be setup for all grades of surrounding rocks with statistical analysis of the on-site displacement data; and then the rule can be used for classification of surrounding rocks. With the wide application of mining method based on the main thought of the new Austrian tunneling method(NATM) and controlling displacement of surrounding rocks in the construction of high-speed railway and expressway tunnels; the above identifying rule of stability and classification method of surrounding rocks will more in line with current technological level of tunnel construction.

Brittle constitutive model and slippage destruction theory were used to analyze the stress distribution and failure mechanism of surrounding rock for deep underground project. The result shows that: Excavation unloading will cause the growth of the shear stress, which leading to the local irreversible (plastic) slip or break; and the surrounding rock will be divided into blocks with certain scale; the frictions between the blocks decide the value of the rest strength. Under the action of uneven compression, it can produce zonal tensile breakage, that made the monitored displacement greatly exceed the calculated value with continuum theory. By considering volume expansion, we can get the conditions that cause the tensile breakage; the calculation shows they are related to the material properties and the brocken scale.

For most of the existing algorithms for calculating ultimate bearing capacity of jointed rock masses based on Hoek-Brown strength theory, they have not considered the effect of intermediate principal stress; so these algorithms cannot make full use of rock strength. Combining the advantage of nonlinear unified strength criterion and Hoek-Brown nonlinear failure criterion, and taking the impacts of earthquake loads into account, a new algorithm for computing the bearing capacity of foundation based on critical sliding field theory is proposed. The experiment results demonstrate that the bearing capacity of the foundation is enhanced based on nonlinear unified strength theory; the existing methods of bearing capacity of foundation are relatively conservative, so the bearing capacity of foundation will reduce under the effects of earthquake loads.

Based on the continuity, non-Darcy momentum and energy equations for fluid convection in porous media, the velocity and temperature fields of riprap slope embankments under strong ventilation condition were studied numerically in permafrost regions in the Qinghai-Tibet railway. The results show that the riprap slope embankments play a significant role in protecting the permafrost, under which the upper limit of permafrost increasing obviously in summer and the re-frozen process is much faster in winter compared to the permafrost under the native ground surface. The cooling effect of riprap slope embankment is limited mainly in the range of near slope embankment; so the centre of embankment can not be protected very well. With the climate warming, a thawing interlayer looks like an eyeball may be formed in the centre of permafrost under the riprap slope embankment, which is not conducive to the stability of slope embankment. The direction of air flow is from down to up along the slope in riprap slope at following wind side; but it is from up to down at counter wind side. The motion type of air flow in the riprap can be defined as roll flow; and the flow velocity is much larger at the surface of riprap than the inner. Besides, the distribution interval of velocity is between 1.24×10-3 m/s and 12.8 m/s; and the numerical result is mainly in accordance with the site test results.

The size effect coefficients of side and tip resistance of large diameter rock-socketed pile under 20 different conditions are obtained by using FLAC3D. The size effect on ultimate bearing capacity of rock-socketed bored piles with diameters of up to 3.4 m for Tainxingzhou Bridge caused by the excavation has been analyzed. The results show that: (1) The smaller the surrounding rock strength, the size effect of ultimate end of the pile resistance and ultimate friction resistance become greater, and the smaller the size effect coefficient. When the surrounding rock strength is 1-5 MPa, the damage of surrounding rock during excavation is obvious; the size effect is obvious. When the surrounding rock strength increasing to 10 MPa, the damage of surrounding rock during excavation is not obvious, the size effect is significantly weakened. (2) Under the same rock strength, the larger the pile diameter, the larger the size effect of the extreme end of the pile resistance and ultimate friction resistance and the smaller the size effect coefficient. Compared with pile side resistance, the size effect is more pronounced and the size effect of tip resistance coefficient is slightly smaller. (3) The relationship between size effect coefficient of ultimate end of the pile resistance and ultimate friction resistance and pile diameter is well fitted with the hyperbolic function.

The soil resistance factor in the internal force analysis and deformation law of plastic concrete cut-off wall is widely obtained by local testing. That the test method has the influence of the complex factors and relies on experience makes the poor accuracy of determination value. This paper gives a method of relatively accurate numerical of soil resistance factor using related theory and field monitoring information. Depending on a reinforcement project that ferroconcrete cut-off wall is concreted on the original plastic cut-off wall; the soil resistance factor is inverted by combining the backfill soil monitoring information with method in the engineering foundation. It gives the analytic equation, influence law in the construction and effective thought about inversion, which establishes the foundation of accurately analyzing the internal force and deformation of cut-off wall.

During the practical construction, deformation development of foundation pit is related to many factors. It is hard to make quantitative analysis with mechanical model. So we can make model based on measured value to predict the deformation trend in a short future time. This model can be used to evaluate and adjust the current construction scheme. Firstly, the characteristics of measured deformation are given. Then the vector auto regression (VAR) model of foundation pit deformation prediction is made by economy prediction VAR model. Lastly, the VAR model precision and prediction ratio are given with measured data. From the prediction analysis, the model precision sorting is VAR model, metabolism model, neural network model and GM(1,1) model. And the prediction ratio sorting is VAR model, metabolism model, neural network model and GM(1, 1) model.

Deep diversion tunnel of Jinping Ⅱ Hydropower Station is located in a high stress zone; for its surrounding rock, i.e. marble, the conventional triaxial test and pre-peak unloading test are carried out. Based on pre-peak unloading test of the marble, its deformation, parameters and strength characteristics under pre-peak unloading are studied; and a power function Mohr strength criterion which can fit the pre-peak unloading tests appropriately, is established. The conditions of pre-peak unloading in numerical simulation is given. By using finite difference procedure of FLAC3D, a numerical simulation model is established; and it is analyzed and compared with the laboratory test result. Finally, the characteristics of the pre-peak unloading rock mass is acquired. The results indicate that nonlinear Mohr strength criterionis can fit to the strength characters of the rock under pre-peak unloading test; at the beginning of pre-peak unloading test, elastoplasticity characteristics is shown; the peak strength and decline of the confining pressure increases continuously as the confining pressure increase. These conclusions reveal the unloading mechanical properties of marble under high geostress and provide reliable theoretical reference for us.

This paper introduces key technologies and methods of comprehensive information automatic collection, wireless transmission，forewarning system in tunnel construction. Combining with modern telemetry technology, the system integrates sensor data acquisition (frequency, voltage, current simultaneously, digital etc.) of selected measuring section, three-dimensional laser scanning, advance geological forecast, blasting vibration monitoring and visualization monitoring. It can realize tunnel construction face image real-time display and analysis，certain tunnel construction monitoring data automatic collection and analysis, form the tunnel construction comprehensive information monitoring system, ensure tunnel construction safety in complex geological conditions of surrounding rock. The comprehensive, real-time and warning characteristics of TIS have an important practical meaning for dynamic design, construction management and improving the construction safety degree.