Abstract:The deducation of analytic solutions for 3D slope stability analysis is the difficult problem in the anea of geotechnical Engineering.Based on the stress analysis of a point in space， the stress analysis of a point on a surface is performed， and then the relationship among the normal stress， the shear stress，the stress component of a point on a surface and the first order partial derivative of the surface equation is deduced. Equilibrium equations of soil columns between the sliding surface and the top surface of the slope are established， which include differential equilibrium equation of force， equilibrium equation of force， and equilibrium equation of moment. These equilibrium equations and Coulomb yield condition can form the fundamental equations of three-dimensional slope stability analysis. Applying the supposition similar to that applied in the simplified Bishop method， a kind of three-dimensional slope analysis method can be obtained. An example is presented to show that the computation method is reasonable and applicable，which provides significance for the further deducation and application.

Abstract:In terms of the range of sliding mass resulting in landslide thrust on stabilizing piles， firstly， this paper established the range of soil-arching effect of sandy-slope behind anti-slide piles based on the pole point theory of Mohr's circle. Moreover， on the basis of Coulomb's theory， the analytical solutions for Coulomb's coefficient of active earth pressure considering the influence of slope angle and lateral stress nearby pile sides with consideration of soil-arching effect were obtained. Furthermore， the analytical solutions for distributed model and resultant force of landslide sliding force acting on anti-slide piles were obtained by adopting the improved solution of the theory of partial plastic deformation which takes account of soil-arching effect. Success of the proposed methods in this paper is illustrated by good comparison with the results of available analytical approach and numerical simulation，which verifies the correctness of the derived Coulomb′s coefficient of active earth pressure considering the influence of slope angle and analytical solution for landslide thrust on anti-slide pile. Finally，the performed parametric study on landslide thrust reveals that landslide thrust and corresponding resultant force increase with the increasing slope angle β， internal friction φ and decreasing the ratio of D1/d.

Abstract:In order to study the energy transfer law of simulated rock containing parallel joints under impact loading，cement mortar meterial was used to simulate rock the ratio of mortar and plaster was adjusted to make the joints. With the help of the disconnect-type SHPB equipment，the rule of energy transfer， strength characteristics，and failure mode of specimens with different joint spacings under the similar impact velocity were studied.The experimental results showed that， in the condition of the same low-velocity impact， the proportion of reflected wave energy， transmitted wave energy and dissipative wave energy were affected by the jointed spacing. The larger the jointed spacing was， the smaller the fragmentation was. The energy transfer law of the two parallel cracks with 18 mm gap of simulated rock specimens was closely related to the impact velocity， and the energy dissipation ratio can characterize the macroscopic failure characteristics. Damage variable with the impact speeds presents an increase weak power function relationship，where d stands for damage variable and v stands for impact speeds in this formula，and the damage value of the specimen is about 0.72. The results of this study provides a reference for the analysis of the excavation supporting and stability controling of multi jointed soft rock under underground engineering.

Abstract:Half screw pile technique has been applied in many kinds of projects. However， due to the limitations of cognitive conditions and the complexity of research objects， the theoretical analysis is still lagging behind the engineering practice. The particle flow code based on discrete element method was used to establish the numerical analysis models of vertically loaded half screw piles， the microscopic parameters of the models were verified by the existing experimental results. On this basis， the effects of the design parameters such as screw spacing， length of the threaded section and external diameter on the bearing characteristics of the half screw piles were analyzed. The research results show that the ultimate bearing capacity of the half screw pile reaches maximum and then decreases with the increase of screw spacing， the half screw pile has the best bearing performance where the screw spacing is （1.0-1.33） D， the load sharing ratio of the threaded section is the highest，while the straight section is the lowest. The ultimate bearing capacity of the half screw pile increases linearly with the increase of the length of the threaded section， and then basically remains unchanged，and it is suggested that the reasonable length of the threaded section is generally not more than 2/3L. With the increase of external diameter， the ultimate bearing capacity of the half screw pile is approximately linear and increasing rapidly. The numerical simulation results can provide some theoretical references for optimizing the design parameters and establishing the bearing capacity estimation method of the half screw pile.

Abstract:Steep foundation uneven settlement affects the stabilization of railway roadbed.Based the field tests and numerical simulation on Neimah railway steep embankment construction the slope ratio，foundation backfill nature，filling height，roadbed compaction degree to steep embankment and it influence on differential settlement were examed.The conclusion shows that embankment slope ratio has some influence on the vertical deformation of subgrade and the larger differential settlement and larger slope ratio results in the increasing total settlement，ground slope has a significant impact on the subgrade settlement and the differential settlement increases with the increasing slope，filling height has a strong impact on foundation settlement and the greater deformation differences leads to the larger variation of the fill section. Filling the elastic modulus has a strong impact on the total settlement of embankment and the embankment differential settlement with the increase of differential settlement modulus gradually decreases.

Abstract:After the excavation of the cutting slope at DK324 of Huaishaoheng line， a slope slump was formed. Through analyzing the spatial morphology， the composition and structural characteristics of the slope slump， and the hydrogeology of the area based on field exploration， investigations and surveying， in-situ test and laboratory test， the cause and mechanism of the slope slide were clarified. Comparing the differences of stress and deformation among single row piles， double row piles and rigid frame anti-slide piles using finite element method， it was found that the rigid frame anti-slide piles performed the best. And the structure of safe and convenient construction was adopted to treat the slop slump. The long term monitoring results shows that the treatment effect of rigid frame anti-slide piles obviously surpasses others. It is of important guiding significance for slope slump treatment in similar projects.

Abstract:The sheet pile wharf with separated relieving platform is a new type wharf. The main structural feature is to install a buried pile foundation unloading platform behind the quay wall of the traditional sheet pile wharf with single anchor to achieve the unloading effect on the quay wall. Based on the engineering prototype， the prototypical numerical model was built. Under the condition of the constant concrete consumption in single-wide pile and wall，the set of comparison models are established. The maximum cross-section bending moment and its edge stress of quay wall and piles are the main criteria to evaluate the effect of structural parameter changes on the bearing characteristic of structure. The results show that， based on the prototype structure， properly increasing the pile spacing and the pile section stiffness can effectively optimize the bearing characteristics of the sheet pile wharf with separated relieving platform under the condition of the constant concrete consumption in single-wide pile and wall， which has a certain reference value for engineering practice.

Abstract:The decision of underground power plant axis direction is vital for previous investigations of a pumped-storage power station. This paper took Zhirui Power Station as the project background， where the surrounding rock lithology of the underground powerhouse was relatively simple with lava breccias， the structure of rock mass is predominantly mosaic to sub-massive， with mainly Grade IV and V structural planes， well-developed fissures and poor integrity. The optimal selection of underground power plant axis direction under complicated fractured rock mass environment was systematically studied. The research comprehensively analyzed the stability of surrounding rock under the combination of different structure planes cutting by using Unwedge program on the base of block theory and value principle of the maximum value of the minimum safety factor. The results showed that the axis direction of underground power plant in study area should be NE50°， demonstrating that block theory had practical significance in optimizing the axis direction of underground power plant under complicated fractured rock mass environment in the low-medium stress area.

Abstract:Cement soil mixed piles are widely used in irrigation works， municipal road projects and urban infrastructure projects due to its advantages of convenience to construction， little pollution to environment， flexible arrangement and economic efficiency. This paper takes the extra large foundation pit support of Foshan new town CBD as the background and analyses the factors affecting the engineering characteristics of cement soil based on themicroscopic action mechanism between cement and soil，which include cement content， water content， age of cement and properties of soil. And strength distributing rule of cement soil is obtained through indoor unconfined compressive strength tests，where the control variables are cement content， comprehensive water content and age of cement. The test results show that the unconfined compressive strength of cement soil increases with the increase of cement content and age， and decreases with the increase of comprehensive water content. Finally，this paper deduces the comprehensive coordination parameter formula for the construction of cement soil mixed method according to the reasonable construction technology parameters， including field mix proportion of cement soil，rotating speed of stirring shaft， lifting and sinking speed of stirring shaft and times of duplicate stir.

Abstract:Based on the laboratory tests on granite， a two-dimensional discrete element simulation method（DEM） of granite based on digital image was studied. Based on the pictures of granite photos，the micro-structure model of granite was reconstructed by digital image technique and the DEM numerical model was established through the reconstructed model. A uniaxial compression test was conducted by the particle flow program （PFC） to calibrate the parameters used in the model. With the use of these obtained parameters， the mechanical properties of granite were studied by two-dimensional numerical biaxial tests，and the deformation and failure mechanism were discussed from a microscopic perspective.The whole process of loading and the morphology of micro-damage were studied in the numerical experiment，and the results were compared with the indoor test results. The results show that the strength characteristics of granite obtained from digital image granite biaxial compression test， the development process of micro-cracks and the specimen failure characteristics are in good agreement with those from laboratory tests. The two-dimensional particle-based discrete element method based on digital image can describe the characteristics of micro-damage of granite with obvious discontinuities in uniaxial and biaxial compression state，and provides an effective method for the further investigation on complex stress conditions under the destruction mechanism.

Abstract:The convergence-confinement method is one of the practical methods for designing the tunnel structure systems. The curve of longitudinal displacement profile for surrounding rock（LDP）is the key to the successful application of this method. On the basis of collecting and arranging the existing LDP curves， the advantages and disadvantages of the LDP curves are compared and analyzed. At the same time， the numerical simulation software is used to deeply analyze the influence of rock mass strength and deformation properties on the curve of surrounding rock profiles. The results show that for the same project， based on the existing LDP curve formula， the curves obtained by the corresponding data differ greatly. The cohesion and friction angle greatly influence the curve shape of the longitudinal displacement profile of the surrounding rock，while the elastic modulus and dilatancy angle have no effect on the LDP curve shape. Poisson′ss ratio has no effect on the LDP shape of the elastic medium.However，the larger plastic deformation zone results in greater effect of the Poisson's ratio. In order to obtain the LDP curve in practical engineering， it is suggested to adopt the numerical method and consider the discrete influence of cohesion， friction angle and Poisson's ratio. The research results can provide for obtaining the LDP curve in the initial support parameters design of the underground tunnel by using the convergence-confinement method.

Abstract:The layout of drainage measures for deep-buried and long diversion tunnels is closely related to the seepage field and the external water pressure of the tunnel， which is an important measure to ensure the safety of surrounding rock and lining structure. Based on the deep buried long diversion tunnel of Dali section II of the water diversion project for the central area of Yunnan Province， ABAQUS numerical simulation method is applied to study the variation rule of the seepage field and external water pressure of the tunnel under different drainage schemes. The results show that the arrangement of drainage measures can effectively reduce the external water pressure of lining， but the reduction extent of water pressure in different parts of lining is different. The external water pressure on lining which is near drainage hole is greatly reduced. And the external water pressure on lining is reduced obviously with more drainage holes. The research results can provide reference for the design of the water control system for deep-buried and long tunnel in Southwest China.

Abstract:Few researches have been done on the health status of a reinforced slope， as well as on the service life and protection of reinforced structures in a slope at present. In view of gray and fuzzy index of durability evaluation influencing factors on anchors in an existing reinforced slope， this article sets up a health status diagnosis method and evaluation criteria of index system on anchors in an existing reinforced slope based on the theories of gray correlation and fuzzy recognition. We put forward a method of evaluation index fusion empowerment value based on information entropy and compound weight according to variation degree of durability evaluation indexes on anchors in an existing reinforced slope. Research shows that the diagnosing method of the health status of anchors in an existing reinforced slope proposed in this paper can reflect health status fully and systematically. Judgment results are reliable and reasonable as well， which provides new ideas and methods for the health status diagnosis of existing reinforced slopes and the design， construction and maintenance of anchors. It has an important significance and reference value in civil engineering fields.

Abstract:If the numerical method of slope stability analysis is based on global strength reduction and local strength reduction method， it can only obtain a single slope safety factor and the numerical reference value of slope in critical instability. In order to analyze the stability of the slope and make the analysis result more accordingly with the actual project condition， through the extrusion function and the designed program by FLAC3D， this article realizes the control of reduction area， strength reduction calculation precision and strength reduction coefficient range. In this paper， the typical earth-rock mixed high slope is the research object， through building a three-dimensional numerical model of slope. Firstly，the slope intensity change area is defined. Secondly，the calculation accuracy is confirmed. Then， strength reduction coefficient range is adjusted according to the actual working conditions. Finally， the stability analysis of earth-rock mixed high slope is realized. The analytical results obtained by the method are in accordance with the actual engineering conditions. The calculation results of the project show that，the numerical method reflects the deformation and failure characteristics and the area of sliding surface in the various stages of the construction. Compared with the traditional stability analysis method， it can better quantify the deformation and failure state of the slope. The results can provide an effective reference for the stability analysis of earth-rock mixed slope.

Abstract:Earth-rockfill dams are a unity of saturated and unsaturated seepage zones. Seepage is thus a key factor for the sound operation of earth-rockfill dams. Soil-water Characteristic Curve （SWCC） is an important basis to simulate unsaturated seepage zones. With a large number of earth-rockfill dams in Zhejiang Province， it is significant to study the water retention capability of the filling soil. Firstly， it is necessary to find a suitable model to describe the SWCC of the filling soil. In this paper， water retention tests were conducted via pressure plate instrument on three typical filling soils for earth-rockfill dams in Zhejiang. VG， FX and MX Models were adopted in fitting the experimental data. The analysis on fitting results suggest that the VG Model was not suitable for earth-rockfill dams， while the FX and MX Models achieved preferable effects，and FX Model excelled at applicability and universality.

Abstract:The common cushion layer used in the geomembrane faced rockfill dam is usually made of granular material such as gravel or cobble. Under the action of water pressure， the puncture of geomembrane is likely to occur at the protruding part of the cushion surface，and the bursting of geomembrane may occur at the void. The rougher surface of the cushion results in the greater possibility of bursting and puncture of the geomembrane under the same conditions. However，there is not a suitable quantitative index to describe the roughness of the surface of the particle cushion. In order to solve this problem， this paper starts from the puncture behavior of geomembranethis and uses progressive method to analyse the surface line of geomembrane particle cushion and a new quantitative index was proposed based on tthe distribution of convex shape. The index is then compared with JRC indexes，and it indicated that the quantitative index proposed in this paper can directly reflect the possibility of geomembrane puncture or bursting occurrence，and JRC indexs is not suitiable to analyse the roughness of granular cushion surface.

Abstract:At present， most scholars at home and abroad usually focus on the stress and deformation of landslide body caused by tunnel excavation. There are few studies on the force， deformation and reinforcement of existing tunnel structures under the influence of landslide. Based on the issue， a new combined reinforcement system of pile and cable in existing tunnel is proposed，where the anti-slide piles， anchor cables and tunnel lining are integrated， which is very different from the traditional study by the separated type between tunnel reinforcement and landslide treatment. However， due to its theoretical research lags far behind engineering practice， it limits the application in engineering practice. In order to study the stress and deformation of the reinforcement measures of the existing tunnel in landslide scope， three geo-mechanical model tests in case of vertical crossing direction are established to study the interaction rules between the landslide and the tunnel structure. It includes the ones without reinforcements，with anti-slide pile reinforcements and with combined anti-slide pile and anchor cable reinforcements. It is found that the test data change significantly after the reinforcement measures are applied. Especially in the combined anti-slide pile and anchor cable reinforcement system， the tunnels， the anti-slide piles and the anchor cables form a new structural system with higher carrying capacity and stability， which can ensure the operational safety of the existing tunnel. The results can provide a theoretical basis for the service reinforcements of the tunnel in the landslide mountain scope.

Abstract:Chinese loess is unique in having great scientific value and also playing an important role in societal development. Large volumes of loess are carried by the Yellow River from the Chinese Loess Plateau to the Bohai Sea， northeast China， forming the Yellow River delta. However， compared to the well-studied Chinese Loess Plateau， our understanding of the change of the geotechnical properties from land to sea is not enough. Consolidated undrained dynamic triaxial strength tests of soil samples collected from tidal flats with different depositional ages are conducted under isotropic consolidation condition， and strain failure criterion was used. Based on the experimental results， the dynamic strength curves and the dynamic pore water pressure developing curves were obtained.Meanwhile，the basic development equation of pore pressure is established. Considering that the Yellow River Delta is formed by large volumes of loess carried by the Yellow River from the Chinese Loess Plateau， northeast China， the similarities and differences between estuarine loess and land loess are disscussed. Our results show that at the end of the tests， the residual pore pressure has a finite value， but the residual strain keeps on developing. And the development of pore-water pressure of both land loess and estuarine loess can be described by a five polynomial under isotropic consolidation. However， the estuarine loess is less susceptible to liquefaction than land-derived loess. The results of this study has implications for hazard mitigation and improves our understanding of the mechanisms responsible for loess-related geological disasters.

Abstract:Atomization is serious during the high dam flood discharges. Different flood discharge and energy dissipation modes have different degrees of atomization. Atomization rain causes strong erosion on the slope surface near the dam，and in some slope infiltration，it often causes deep sliding slope disaster. A deposit of a power station downstream was selected to establish unsteady seepage calculation model， and different conditions for numerical simulation were developed to study the changes of expansion process of transient saturated areas and changes of safety coefficient and the relationship. The results show that the influence of different atomization rainfall intensity on water infiltration slope were different， and the greater intensity of atomization rain led to greater transient saturation area and the smaller stability and safety factor of slope，where the safety-factor was reduced to at most 6.57%.

Abstract:The method that investigating the relationships between macroscopic and grain-scale parameters of unsaturated soils is proposed， which set up the calculation models of discrete element in different porosity ratio and moisture content under different stress path. By the discrete element program， the existing PFC3D （particle flow code in three dimensions） was improved，and one-dimensional consolidation test of discrete element specimens in the different particles bond strength was carried out to determine the structure yield stress. In this paper， the relationship between intergranular bond strength and moisture content is established by means of structural yield stress， which can reflect the value of the actual sample size and the different water content and provide the idea to study the basic mechanical properties of unsaturated soil through PFC3D.

Abstract:The angular velocity is always neglected， which is the key problem of impact force design and movement path calculation of rockfall. This paper analyzed the response of the five process， i. e. free falling， sliding， projectile motion， impacting and rolling to the angular velocity of rockfall， and deduced the angular velocity formulas of rockfall under the rolling and impacting movement.Meanwhile， taking the Fujian Primary Pchool rockfall in Tianshengcheng， Wanzhou District for example， it can be concluded that the angular velocity was only related to free falling， impacting and rolling when it ignored the conditions of air drag； the angular velocity of rockfall under the impacting movement presented positive correlation with the initial angular velocity， impacting period， slope gradient， rockfall mass while it presented negative correlation with the rockfall radius， impacting friction coefficient and normal restoring coefficient； the angular velocity of rockfall under the rolling movement developed positive correlation with the initial angular velocity， rolling period， slope gradient， while it developed negative correlation with the rockfall radius， rolling friction coefficient. Through the case of Fujian Primary School rockfall，this paper obtained that the variety trend of angular velocity curve was consistent with this paper's methodology and the Rocfall Program， and the average error is just 5.5%. Thus， the methodology proposed in this paper fully meets the engineering requirement.

Abstract:The retaining wall structures have always been designed for supporting talus in karst mountainous area. Because of large particle size of talus， its mechanical properties are very different from fine grained soil，However，most theories and experiments based on continuum theory took the fine grained material such as fine sand as research object， while less research on active earth pressure of large particle size such as talus was performed. Aiming at these problems， the discrete element method was used to simulate the active earth pressure of fine grained soil in translational displacement mode of retaining wall as well as talus in different particle size. The rule of active earth pressure with particle size was obtained through summarizing the results， and the point of active earth pressure correction formula which considered particle size was also deduced.

Abstract:In the investigation of leakage in Sanmentou Section of Main Channel of Yanshiling Reservoir， as the channel is located in the karst development area， the multi-dimensional method of parallel electricity method was combined with geological radar to study the causes and distribution range of hidden defects.Based on analyze the feasibility of the integrated geophysical exploration technology，using the method of parallel electricity， considerable geoelectric data volume was collected rapidly to support 2D dam leakage detection and survey hidden defects of channel bottom. In combination with radar imaging， development characteristics of karst caves was identified effectively. Practical application demonstrates that 2D resistivity images of different elevations reflecte the scopes and depths of potential hazardous dam areas of leakage and spatial connectivity of potential hazardous areas；3D results obtained by the method of parallel electricity reveal three-dimensional structure of karst caves on the bottom of the channel and avoid complex problems of conventional pseudo-3D electrical layout. In addition， geological radar can identify the scope of karst development effectively. Comprehensive results of detection show that dam leakage in the Sanmentou Section is mainly related to its concealed filling karst caves； and there are tunnels connecting upstream and downstream caves. Further case studies show that the multi-dimensional imaging technology of parallel electricity and geological radar have a high precision of location with dam leakage in the karst area， thus providing a basis for objectives-oriented dam governance.

Abstract:Ngong tunnel， which is designed for single track railway tunnel， is located in the Great Rift Valley. It has 4 507 meters long，and it is the control engineering of the railway from Nairobi to Malabar. The surrounding rock of Ngong tunnel is mainly basalt in the III and IV levels. The drilling and blasting tunnel is excavated by bench excavation. We obtain the attenuation law of blasting vibration considering the dispersion by blasting vibration test and data analysis for evaluating the influence of blasting damage of Ngong tunnel on surface structures. According to this， we develop the safety evaluation of the influence of blasting damage of surface structures along the Ngong tunnel. The research achievements provide a scientific basis for blasting working and safety control of Ngong tunnel.

Abstract:Based on the on-site monitoring data， the dynamic response of Gongqiaopu tunnel under the dynamic load and the influence of lining are studied by FLAC3D. Under the dynamic loading at the bottom， the lining tunnel can change the direction of movement of other measuring points except the arch bottom，compared to the tunnel without lining. To prevent the tunnel from being inverted and effectively reduce the anchorage wall displacement of the tunnel， the wall rock of the tunnel is more “loose” when its four points are subjected to the compressive stress and the pressure value is much less than that of the lining. There are neutral points in the axial force of the anchor rod in the arch shoulder of the tunnel with lining support， while the anchor rod is pulled when the lining is not supported， and the latter is more close to the anchorage wall. The lining can effectively share the surrounding rock load and reduce the load of the anchor rod， the axial force of the anchor rod is relatively fast and the amplitude is large when the lining is in， and the tunnel with no lining supporting is under the shock of stress wave. The axial force of the anchor rod is relatively slow and the amplitude is small，which illustrates that the lining can support the dynamic load by dynamically adjusting the anchor rod.

Abstract:Bedding rock slopes widely exist in the construction of hydro-junctions， which stabilities are affected by weak planes like joints. In general， the bedding rock slopes are reinforced by bolts， and it is of great importance to study the reinforcement mechanism when it comes to the design and construction of bolts. Firstly， the contact model considering the bond size was implanted into a distinct element method （DEM） software PFC2D to establish the model for the bedding rock slope， where three sets of bolts with different lengths were introduced to form the model for the reinforced slope. Then， the failure processes of the unreinforced and reinforced slops were simulated with the gravity increase method. Finally， the reinforcement effect and mechanism of the slope by bolts were analyzed by comparing the safety factors， failure patterns and force chains distributions of the unreinforced and reinforced slopes during the failure processes. The results show that the slope safety factor obviously becomes larger in the reinforced slope， and thus the stability is improved and the reinforcement effect is obvious. Compared with the unreinforced slope， the failure pattern of the reinforced slope stays unchanged.However， more time is needed for the failure to occur， the sliding surface is shallower and the amount of slip masses is smaller. The bolts improve the stress state of the slope，and in the unreinforced slope， the tensile and compressive forces concentrate on the rock bridges， while in the reinforced slope， the bolts holds most of the tensile forces and the rock bridges basically only resist the compressive forces.

Abstract:To investigate the characteristic strength of single calcareous sand under the quasi static load， a high-precision single- particle loading apparatus was manufactured to carry out a series of single particle crushing tests on the calcareous sand with different size and shape obtained from South China Sea. Then the measured data were further statistically analyzed with the Weibull distribution function and the strength of single calcareous sand is normalized. The results show that failure mode of the single calcareous sand can be classified into three modes from the force-displacement curves， i.e.， hardening mode， softening mode and flat mode. The compressive strength of the single calcareous sand decreases with the increasing particle size and it is higher for block particles than that for flake particles at the same particle size. In addition， the strength distribution of the single calcareous sand shows a good agreement with the Weibull distribution， where the Weibull modulus m lies into the range of 1 ~ 3.

Abstract:During the shield tunnel excavation through the complex environment with many kerst caves，stress field of karst cave can ke changed suddenly. Moreover，it also resulted in engineer disaster，such as cave collapse， water dashes forward in karst area. The finite element emulation method is used in the paper，and two important factors for the numbers and the arrangement of the caves during excavation is simulated. Displacement field， stress field and plastic zoon of the surrounding rock of tunnel are analyzed. The results are as follows: The existence of karst caves greatly increases the maximum principal stress of the tunnel surrounding rock； The vertical displacement of the surrounding rock increases with the number of caves；The stress field， displacement field and plastic area of surrounding rock have different changes according to the relative position of the tunnel. The results can provide theoretical and engineering guidance for the design， construction and operation of shield tunnel in karst region.

Abstract:The seepage-stress coupling characteristic of practical engineering rock mass under 3D unequal principal stress is a key point in the academic and engineering fields. A reasonable formula for stress-seepage coupling characteristics of rock mass with a single rough joint is deduced based on the theoretical analysis. The feasibility of the theoretical expression is verified by the indoor true tri-axial stress-seepage coupling tests. Based on the test data， a reliable empirical formula is given by the powerful data fitting software. The numerical experiment is carried out by the 3D distinct element method. The difference of the methods on choosing joint normal stiffness parameter is discussed. The empirical formula is also verified by the numerical simulation based on reasonable assigned parameter values. The theoretical analysis is fully tested by the indoor true tri-axial stress-seepage coupling tests， the credible non-linear fitting and the numerical simulation.

Abstract:To improve the development of Unmanned Aerial Vehicle （UAV） oblique photogrammetry technology， this study detailed the development history， research status and hot research topics about this technology for engineering applications. Firstly， the development history， current research status and technical advantages of UAV oblique photogrammetry are introduced systematically. Secondly， the key operational procedures of UAV oblique phtogtammetry were analyzed in detail， covering camera calibration， image location， flight plan， image acquisition， surface 3D reconstruction and product generation. Thirdly， the applications of UAV oblique photogrammetry in engineering field were illustrated， such as the digital city construction， bridge inspection， landslide survey， topographic map. Finally， the study illustrated the the development directions and key issues for UAV oblique photogrammetry. The comprehensive analysis shows that the UAV oblique photogrammetry can be apply to geospatial data acquisition with features of large scale， multi-data and high efficiency， which has broad application prospects in engineering fields such as civil engineering， traffic engineering， surveying and mapping engineering.

Abstract:Annular arched girders structural support system bears pressure mainly， which is conducive to play compressive strength of concrete materials reasonably and convenient to conduct construction. The single annular arched girders structural support system is suitable for regular pit whose aspect ratio is close to 1. For the irregular pit with large aspect ratio， double annular and even multi-annular support has been applied in some projects. An irregular “L” shaped foundation pit in Shanghai soft soil area with area of nearly 50 000 m2 and a maximum excavation depth of 13.15 m applied double annular support system. The foundation pit used top-down method and is designed into A， B， C three zones，where zone A applied double annular support system，zone C is supported by side girders and angle diagonal brace，and zone B uses angle brace to support， working as a transition zone. Based on in-site monitoring data， this paper investigated the movement of lateral wall， subsurface horizontal movements and surface subsidence. Based on these data， this paper summarizes the deformation and force bearing characteristics of double annular support system， which can provide valuable reference for applications of it in deep foundation pit engineering.

Abstract:It is the key problem to ascertain rock engineering parameters in numerical calculation. Rock engineering parameter accuracy affects the outcome of numerical calculation. However， it is difficult to get the true rock engineering parameters because of the scale effect in laboratory and insufficient quantity of sampling. Many factors can be considered by back analysis method，which can get the rock mass parameters accurately. For the positive and negative analysis method， the planned back analysis parameters are postulated at first， and the displacement or stress of rock mass is obtained by positive and negative analysis. By comparing the displacement or stress of rock mass with the monitoring data， the back analysis parameters are adjusted step by step until the displacement or stress of rock mass approximates the monitoring data. Finally， the right rock mass parameters are obtained. By abroad maritime tunnel of mudstone， rock parameter back calculation is carried out on the basis of the monitoring data. The actual rock engineering parameters are obtained by analysis and comparison，which lays a foundation for ascertaining tunnel initial support parameters.

Abstract:Sandy pebble stratum is a kind of typical mechanical instability stratum. Shield tunneling often encountered difficulties such as unearthed difficulties， cutter disc wear and groundwater gushing. Aiming at the complex variability of the material composition and structure of this kind of stratum， sandy pebble soil sampling are selected in Luoyang Metro Line 2， and the properties of sandy pebble soil under different stone content are studied by using large direct shear test， slump test and permeability test. The results show that the shear strength and internal friction angle of sandy pebble soil increase nonlinearly with the increasing of stone content， and the shear strength and friction angle increase slow when stone content is less than 30%. The shear strength and internal friction angle increase significantly when the stone content is 30%~70%， and the shear strength and the internal friction angle are not obviously changed when the stone content is more than 70%. The slump of sandy pebble soil decreases with the increasing stone content and a demarcation rate of about 50% of the stone content is found. The permeability coefficient of sandy pebble soil increases with the increasing stone content and shows a similar rule like the shear strength and the internal friction angle.

Abstract:Following the energetical development of engineering construction，basement excavation is developing to deep and large direction， and the surrounding condition is getting more and more complicated. According to an engineering project，deep and large pit scheme analysis is conducted in detail. The foundation pit is adjacent to using metro， proposed metro， large residential district， existing office， municipal road， et al，and the surrounding environment is primary complicated. Foundation pit circumference is even 1000 m，excavating depth is even 16.0 ~ 20.0 m，and it is typical deep and large foundation pit. By multi-scheme comparison， the foundation pit support is picked up，and the scheme includes rowed pile and internal support， rowed pile and anchor， rowed pile and steel inclined brace， et al. The design scheme is adjusted in the whole construction process according to monitoring data and the surrounding condition change. The foundation pit is constructed in block lasting 3 years and leading twice delayed conference. However，there is no substance safety accident in the whole construction process， and the expected effect is achieved. The engineering project can provide reference for similar projects.