A large deformation would be produced and failure occurs for saturated clay under undrained heating condition at a constant total nonisotropic stress state revealed by test data. Heating should be thought as another loading way. Firstly, an expression of undrained shear strength considering thermal effect is obtained based on the thermal unified hardening (UH) critical state model proposed by Yao et al. Comparison between simulation and test data about undrained shear strength under heating condition for overconsolidated clay with different over consolidation ratios(OCRs) has shown that the variation regularity of undrained shear strength considering thermal effect can be described using the proposed formula. The process at a constant total nonisotropic stress state with heating under undrained condition is simulated using thermal UH model. The prediction result has shown that the thermal UH model can be applied to describe stress-strain relationship and variation regularity of shear strength under undrained condition for saturated clay reasonably. Finally, the value of deviatoric stress ratio at initial time for heating, the magnitude of heating, OCR and preconsolidation pressure are all discussed and analyzed. The regularities of stress-strain relationship and property of strength for saturated clay under undrained condition affected by above factors are obtained

In order to study the grouting reinforcement effect of structural plane in cracked rock mass of uniaxial compression test, and reveal the essence and mechanisms of grouting reinforcement, the roughness of structural plane in cracked rock mass was measured and studied. The influence of grouting on strength, joint roughness coefficient (JRC) and stiffness of structural plane was analyzed through the shear test of structural plane of rupture rock sample around grouting reinforcement; and the test result was back analyzed by using JRC－JCS mode. The mechanical properties and grouting effect were analyzed through the shear test of sawtooth structural plane modeling around grouting reinforcement. The results show that the JRC of structural plane in artificial cracked rock of the same rock mass is similar and replicable，and the value was about 8-10. Stiffness, peak shear strength, residual strength and slope of upward section of structural plane were significantly improved by grouting reinforcement. The theoretical formula of structural plane stiffness was given by theoretical analysis. The peak shear strength, residual strength and cohesion of structural plane increased markedly with the increase of sawteeth number on structural plane and after grouting reinforcement, but little change in the internal friction angle.

Uniaxial and triaxial tests of foam concrete show that the foam concrete which has the capacity of high compressibility can be used as filling material between primary support and secondary lining in deep soft rock tunnel. And the effects of this filling material which is called preset deformations layer on long-time stability of Yi-Ba expressway is studied. The results show that the creep deformation of surrounding rock in deep tunnel still increase after the construction of secondary lining; and it is hardly to be controlled by the method of increasing the thickness of lining; besides, the secondary lining is more easily destroyed by deformation pressure. However, preset deformation layer of foam concrete is able to decrease the deformation pressure on secondary lining by absorbing the creep deformation of rock. As a result, long-term stability of deep soft rock tunnel can be guaranteed by much thinner secondary lining.

Field shear creep test is the most important means to understand the shear creep properties of rock mass. Field shear creep tests are carried out for the dam zone “hard brittle shatter” diabase dikes in Dagangshan hydropower station. The deformation law of shear creep and the characteristics of shear creep rates have been analyzed. The test results show that decay and steady creep only occur when shear stress is relatively low; however, the shear creep rate changes from gradual growth to sudden growth when shear stress reaches the yield strength, the rock breaks in a short time and the acceleration creep appears in the process of shear creep test. Under the constant normal stress, the relation expression between steady-state creep rate and shear stress of diabase can be expressed by an exponential equation. According to the shear creep curves of diabase, the shear creep model of rock is identified. The identification results show that Nishihara model could effectively describe the shear creep properties of dam zone diabase dikes. The shear creep parameters are got through the optimized back analysis method, which provides important mechanical parameters for design and construction of slope in dam zone.

Aiming at the problem of continuous water seepage, spraying and gushing along the borehole of bolt (cable) in rock stratum with rich water, a new waterproofing anchorage agent is introduced; and the corresponding waterproof reaction mechanism and its ratio test on this cartridge are researched. To obtain the strengthen change law of siltstone upon the condition of continuous seepage in the broken roof, the seepage experiment is done respectively in the coal field and laboratory, and the results show: Unsaturated polyester resins of NS-1 and polymer instant rubber powder of XS-1 added with a ratio of 2% are the key points for waterproofing anchorage agent. In the 5 days experimental period, the compressive strength of the experimental siltstones suffering from the continuous effect of the static water experience the change process from the former groups increasing gradually to the two later groups decrease quickly. In the circulation effect between flowing water and air dry, the fracture apertures of siltstones continue increasing in 36-42 h, and the whole strength decreases step by step. On the basis of the experimental observation, the coupling relation between the flowing water in siltstone roof and the supporting structure is thoroughly analyzed. Finally, the results for the bolt and cable anchoring force test with new anchorage agent and supporting application on roadway No. 101101 of Tuanbai coal mine show that cable anchoring force could achieve 208 kN with the draining water content keeping 140 mL/s and applying high pre-tightening force and adopting waterproofing cartridge could solve the supporting problem of continuous seepage in the roof, which ensure the safety and stability of the roadway

Based on the laboratory creep experiments and in-situ tests of mudstone, a nonlinear creep constitutive model with the Mohr-Coulomb creep potential considering hydro-mechanical coupling is put forward by analysis of creep deformation mechanisms of clay; and the damage evolution equation is set up by constructing the relation between creep damage and creep strain. A fully coupled hydro-mechanical model of mudstone is established to describe the evolution of porosity and permeability with strain and damage. The self-healing mechanism of mudstone fractures is investigated, which is effected mainly by the confining pressure, pore water, time for saturated state and so on. A permeability healing model is established by introducing the conceptions of healing stress and hydro-chemical factor. The results show that the creep strain rate of mudstone is not only related to time and stress, but also to the cumulative creep strain. The creep damage of mudstone is caused by the initiation and propagation of new fractures, which is the comprehensive expression of the coupling between deformation and time effect. The presented creep damage model can well describe the creep process of attenuation phase, stabilization phase and the speedup phase and the damage process with less material parameters. The numerical algorithm, numerical implementation and further application of the model are provided in Part Ⅱ of this paper series.

Through the model test of blast-resistance structure of the tunnel, the deformation behaviour of the surrounding rock and lining structure of the tunnel is studied. The principle and method of plane charge explosion model test is introduced. Based on the test results, the stress peak value distribution characteristics around the tunnel under the design load and overload conditions are analyzed. The deformation behaviours of surrounding rock under the above two conditions are put forward. Contrast analysis is carried out in several aspects, including relative displacement between arch crown and tunnel floor, strain peak value around the tunnel wall, variation of strain on the tunnel wall with time, etc. Test results show that the supporting structure of lining can improve the blast-resistance ability of the tunnel efficiently. It is an important technical method to improve the resistance grade of the tunnel.

Based on system for structure and surrounding rockmass of highway tunnel, a three-dimensional model tests about forked tunnel with different altitudes were carried out to study the influence of construction of new forked tunnel with different altitudes on existing tunnel. Existing tunnel’s internal forces of supporting structure, surrouding rockmass internal pressure and internal displacements induced by constructing new tunnel, were measured. Testing data show as follows. Existing tunnel’s crown radial stress and hance tangential stress are keeping increasing, and crown tangential stress and hance radial stress are keeping decreasing. Surrounding rockmass internal displacements are compression deformation at crown and tensile deformation at hance. Existing tunnel’s axial forces and bonding moments of supporting structure keep increasing; and right hance moment of supporting structure increased most obviously. Constructing new tunnel has bad influence on existing tunnel’s section L1 and L4, and has little influence on existing tunnel’s section L8. The area in which adjacent spacing is less than section L8 should be strengthened.

Twenty-one field explosive enlargement tests were carried out on six different soil test sites. The embedded charge were 0.05-51 kg and their embedded depths were 1.20-12.5 cm. Five explosively formed cavities were employed for the soil mechanical test on the variation patterns of natural density, pore-solids ratio, saturation degree, compressibility, compression modulus, internal friction angle and cohesive strength. The test results show that the radii of soil mass affected by explosion are four to six times larger than radii of explosively formed cavities. Soil performance indices such as natural density, dry density, saturation degree, compression modulus, cohesive strength are decreased with the increasing of distance to the center of charge. The indices such as pore-solids ratio, compressibility, coefficient of permeability are increased with the increasing of distance to the center of charge. No low-density region where density is lower than undisturbed soil is found around the caves. The variation pattern of internal friction angle of soil by explosive shock is not clear

With the GDS dynamic triaxial system, undrained dynamic triaxial tests on the saturated sand of different fines contents were performed; and effects of fines content on the dynamic elastic modulus and damping ratio were analyzed. Results show that the dynamic elastic modulus of sand decreases with increasing of fines content; but the trend is reversed beyond the critical value of fines content of 30%. The damping ratio of sand firstly increases and then decreases with increasing fines content at the same critical value of fines content of 30%. When fines content is less than 30%, the dynamic characteristics of sand is determined mainly by the coarse grains; the skeleton void ratio between coarse grains increases with the increase of fines content; and the ability to resist deformation under the same strain level weakens so that the elastic modulus decreases. Meanwhile, the stress wave propagation speed slows down because of the reduction of contact points between soil particles, hysteresis quality of the soil dynamic load response strengthens and the damping ratio increases; when the fines content is greater than 30%, the dynamic characteristics of sand is determined mainly by the fine grains; the interfine void ratio decreases with increasing of fines content; so that the dynamic properties of sand shows a reverse trend.

The shock failure mechanism of zonal disintegration within surrounding rock in deep chamber is put forward. The transient unloading in surrounding rock creates dynamic action on rock near cavern periphery. In the process of redistribution stress in surrounding rock, the discontinuity plane of the radial stress at wave front existed as the elastic longitudinal wave moves ahead. When the parameters of discontinuity plane satisfy certain condition, a local shock destruction occured. Based on the elastodynamics theory, the dynamic problem can be expressed by displacement potential function; and the general solution of motion equations can be obtained by using Laplace transform. The radial stress field in surrounding rock induced by excavation is obtained. The unified solution of differential pressure at wave front is deduced. The shock constitutive equation and failure criterion on zonal disintegration within rock mass are analyzed based on particle velocity, differential pressure at wave front and conservation of momentum. The crtical value of differential pressure at wave front is obtained as shock failure is generated; and the formula of radius of the fractured zones is got. It shows that there exist the equal ratio relations between the radii and the ratio of equality is .

Soil water characteristic curve (SWCC) is one of the most important parameters for unsaturated porous media. Full SWCC is made up of 3 parts, which are initial drying curve(IDC), main drying curve(MDC) and main wetting curve(MWC) respectively. A lot of time has to be spent to perform a traditional hydralic hesteresis test. Based on the data from literatures, an empirical model is developed. Provided IDC and MWC in a certain porous media have been obtained by tests; this model, including only one material parameter, can be used to simulate an incremental-type MDC in the porous media. It is found that the simulating results agree well with the measured data; and it is shown that the proposed model is capable to describe MDC

Dynamic triaxial compressive tests for different weathering degrees granite were conducted with loading rates 1-105 MPa/s and confining pressure 3 MPa. The results show that the compressive strengths of the different weathering degrees granites are all increase with the increasing of the loading rate; and the increment of the compressive strength increases with the increasing of the weathering degree. The Young's moduli of the different weathering degrees granite are all increase with the increasing of the loading rate; and the increment of the Young’s modulus remain unchanged with the increasing of the weathering degree. The Poisson's ratios of the different weathering degrees granites are all decrease with the increasing of the loading rate

The heterogeneity of soil in geotechnical engineering is relatively common, while the analysis method for the face stability of tunnel in nonhomogeneous clays is not well established so far. A simple method for evaluating the undrained stability of plane strain heading tunnel in soft clays is presented. Rigorous upper bounds on the loads required to resist collapse are derived using a rigid block translational collapse mechanism on the basis of plastic limit analysis. The variation of shear strength with depth and the gravity of soil are considered in the study. To verify the quality of the upper-bound solutions, the results are compared with those obtained from the finite element limit analysis. It can be proved that the upper-bound method of limit analysis is a feasible approach for the face stability analysis of tunnel; and it also provides an important theoretical basis for the practical geotechnical engineering.

Two types of over-consolidated ratioes are defined. Undisturbed and remolded saturated loess are tested by undrained shearing test under different confining pressures and over-consolidated ratios. On the base of the definition of stress sharing ratios, the relationship between stress sharing ratio and strain level is obtained from test results, which behaves as two phases. Structure releasing coefficient is defined and it is used to analyze the stress sharing ratio curve. The results show that, under two types over-consolidated ratios, the structure releasing coefficient’s regulation of samples with the same pressure but different over-consolidated ratios is unanimous; under different pressures and two types over-consolidated ratios, the coefficient has the same characteristic. On the base of that, a model and the corresponding formulation are put forward to describe the structure’s regulation. The formulation is a three phases fuction which has a simple form with only two parameters. The comparative analysis indicates that the calculation results have a good consistency with the tests

This paper focuses on solving a one-dimensional nonlinear consolidation problem with the complementary algorithm. Firstly, a piecewise linear function is used to fit the compression curve of foundation soil. With a control variable introduced, a unified relationship between the void ratio and the effective stress and complementarities of compression curve are obtained. After the differential equation of one-dimensional nonlinear consolidation derived in detail, which including void ratio and effective stress as variables, the problem of nonlinear consolidation at different stages is translated into a standard linear complementarity model by carrying out the finite difference method combined complementarities of compression curve. Consequently, problem of nonlinear consolidation can be solved by linear solving method with the complementary algorithm embedded in. Then, the method proposed here is validated by contrasting with general iterative method. On the basis, the difference of linear and nonlinear solution and all the factors of nonlinear calculation are investigated. And it is found that complementary model algorithm method is superior to general iterative method in calculation efficiency; and it is easy to carry out when embedding the complementary algorithm into a linear calculation program to compute nonlinear consolidation. Also, with the solution of control variables in complementary model algorithm method, the compression condition of foundation soil can be estimated

The bifurcation analysis was derived in three-dimensional stress states by using a critical state constitutive model by Yao et al. (2004), which based on the nonassociated flow rule. Theoretical analysis shows that, bifurcation is dependent closely on the stress path. Bifurcation occurs in the hardening regime under the Lode angle changing between minus twenty-five degree and fifteen degree, and the stress ratio, principal strain at bifurcation and inclination angle of shear bands first increase and then decrease with increasing of the Lode angle. But there is no bifurcation occurring in other stress path under constant mean stress. Finally, the return mapping algorithm is adopted in order to implement the model into a nonlinear finite element analysis software ABAQUS through the user material subroutine (UMAT) interface. Numerical simulation results show that the bifurcation also exists in the numerical analysis. The comparison between the numerical results and theoretical solutions indicates that both are in good agreement.

With the application of continuum theory of mixture, which takes the three-phase media, including grains, fluid and ice into account, the dispersion equations of body waves are established for saturated frozen soil by considering Bishop’s effective stress formula. The equations are described with skeleton displacement, pore water displacement, pore water pressure and pore ice pressure. The analytical expressions of wave velocity and attenuation are deduced. The effects of frequency and the parameters of saturated frozen soils on the velocity and attenuation of three kinds of body waves (P1 wave, P2 wave and S wave, respectively) are investigated by using numerical method

Aiming at the shortcoming of the existing consolidation theories of composite ground without considering nonuniform distribution of initial excess pore water pressure in practical engineering, the consolidation theory of composite ground with granular columns is studied in-depth by analytical method; and a general analytical solution is given to the consolidation problem for the composite ground with granular columns under nonuniform distribution of initial excess pore water pressure. The three special cases for nonuniform distribution of initial excess pore water pressure are discussed; and the expressions of average excess pore pressure and average degree of consolidation are derived under the rectangular (uniform), triangle and inverted triangle distribution of initial excess pore pressures. The results show that the distribution of initial excess pore water pressures has obvious influence on the consolidation of the composite ground with single drainage boundary. Under the uniform and triangle distribution of initial excess pore pressure, the excess pore water pressure dissipates gradually with the increase of Tv, and the one is always maximal at the bottom of foundation during consolidation; under the inverted triangle and trapezoidal ( pB /pT =0.5) distribution of the initial pore water pressure, the Tv value is bigger, the excess pore water pressure isochrones are gentler, and the position of maximal excess pore pressure shifts from the top of foundation to the bottom; the change of excess pore water pressure reflects the characteristic “from small to big, and then smaller” in the consolidation process.

Based on the mirror image method for the spherical cavity expansion with nonaxisymmetric displacement boundary, assuming that the soil as the linear elastic constitutive model, the soil compaction displacement field is obtained through the modifications of surface boundary stress and inclination boundary stress, the soil compaction displacement field could consider different boundary angles, different distances from spherical cavity position to the boundary, etc. The results indicate that the influence of boundary inclination angle on the soil compaction displacement would be gradually smaller with the reduce of inclination angle; and the larger distance from spherical cavity position to the boundary, has the smaller influence on the soil squeezing displacement. The results provide some reference for similar engineering design and parameter settings.

An analytical solution is proposed for the Biot’s consolidation theory within a finite two-dimensional (2D), isotropic, homogeneous, and fluid-saturated poroelastic media due to a point sink when the pore pressure is prescribed on the boundary. The analysis is based on compressible porous media models. Fourier and Laplace transforms and related inversions are implemented; and the exact solutions in the form of double summations of infinite series are obtained. In particular, the steady-state analytical solution due to a point sink of constant pumping rate is presented and validated by the exact solution available in the literature. The proposed analytical solution is applicable for testing the accuracy of numerical schemes; and it also can be used to further understand the behaviour of flow and deformation coupling in a finite 2D domain.

A vacuum compression device is developed for preparing silt soil samples with different strengths, and triaxial test is performed for measuring liquefaction characteristics of those soil samples. The relationship between soil strength and cyclic shear stress ratio, pore pressure growth model and its parameters are established; and the impact of the soil strength and the dynamic stress on the liquefaction is discussed. Some conclusions are drawn as follows. (1) During soil samples preparation in the vacuum compression device, excess pore pressure dissipated completely within 24 hours, penetration resistance up to 300-400 N; undrained shear strength up to 8 kPa, reached weak soil strength at the Yellow River estuary. (2) The relationship between soil strength and cyclic shear stress ratio is basically linear; and the higher soil strength, curve of pore pressure on the growth showing the more convex trend, the greater pore pressure ratio reached when destroyed. (3) Index model can better simulate pore-water pressure growth of silt at the Yellow River estuary, where the parameters a and b are located between 0.77-5.63 and 0.17-4.65, respectively; for the pore pressure ratio upper limit, the parameters a and b are 0.92 and 4.65 respectively; for pore pressure lower limit, the parameters a and b are 1.25 and 0.89 respectively.

The viscosity of fluid is time-dependent, which has an important influence on building grout diffusion model. Combining with rheological equation of Bingham fluid and time-dependent characteristic of fluid viscosity, the rheological equation and seepage motion equation based on Bingham fluid of time-dependent behavior of viscosity were established. According to some assumptions，column–hemispherical penetration grouting mechanism about them was deduced and the relationship was also probed into between diffusion radius l1 of hemispheroid and diffusion length m belongs to cylinder: m=(2l1 /3)(2n+1). Then they were validated by means of designing indoor grouting experiments. Experiment results show that in term of diffusion radius of hemispheroid, diffusion length belongs to cylinder and volume of grouting diffusion body, theoretical values calculated by column-hemispherical penetration mechanism formula in view of Bingham fluid of time-dependent behavior of viscosity have respectively about 15%, 10% and 40% of the differences with the actual measurement values by indoor grouting experiments; but they are all within the acceptable error limits. Therefore, it could better reflect column-hemispherical grouting infiltration law based on Bingham fluid of time-dependent behavior of viscosity in the general and may play a guiding role and provide some reference valuable in the design, construction and theoretical research of grouting technique.

Taking the irregular developed anhydrock in dolomite layer of Yi-Ba section which located in Hangzhou-Lanzhou highway as research object, and adopting test methods such as X-ray diffraction experiment, ion-chromatographic analysis, environmental scanning electron microscopy and energy spectrum analysis tests, it is mainly quantitatively analyzed the damage of anhydrock to the tunnel structure. The result shows that the damage to the tunnel structure mainly displayed in hydration-swelling action, sulfate erosion generated by corrosion and the aggravation of dolomite corrosion by acid environment. On this basis, combining with regional engineering geological condition of this area, this paper proposes the deterioration mechanism of the tunnel concrete protective structure under anhydrock and the coupled corrosion action of the anhydrock and dolomite. Finally, it gives treatment suggestions for the similar engineering, mainly by lowering the groundwater level and improving the performance of the concrete.

Based on the background of a complex tunnel constructed in Tibet, a large-scale shaking table test is accomplished to study the seismic responses of the tunnel through fault. The paper introduces the test including the decision of model similarity ratio, the design of model box and the treatment of boundary, the making of model, the layout of monitored points and the input scheme of seismic wave and so on. The test focuses on the rule and character of the dynamic response of the tunnel through fault. From the test, it is concluded that there are some similarities in seismic response between the tunnel through fault and the tunnel through homogeneous rock. With seismic wave upward propagating, seismic response of rock and soil is increasing and the tunnel lining in fault is damaged severely. There is a certain influence on seismic wave propagation because of fault.

Rock bursts are often observed during the excavation of deep rock engineering; and most of them occur some time after the excavation. The time-lagged uniaxial compressive test for the marble from Jinping II Hydropower Station was conducted to study the time-lag properties of rock burst. The test results show that: the hard brittle marble obviously performs time-lagged destruction under long time of pre-peak stress uniaxial compression. Many vertical cracks occur during test process; and lots of sheet debris are created when the marble failure. The circumferential strain of marble sample is larger not only than its axial strain but also larger than its circumferential strain by conventional uniaxial compression test. The dramatic brittle failure of marble may happen more frequently if the circumferential strain approaches or exceeds the axial strain. The research results will play a great role in understanding the mechanism of time lag of rock burst and establishing the prediction method of rock burst.

As an important invention, reinforced soils have been using widely in retaining walls, dams, bridge works, slopes, etc. The rapid growth of reinforced soils has been pushing the development of reinforced materials, such as geotextile, geogrid, geocell and so on. These geotechnical materials have weak point: potential failure surface is liable to appear. In the past, clay and sand were used as stuffing, their strengths are stable and less affected by the time. The lime-soils strength has much to do with the time, if it is used as filling material, is it suitable? In this paper, an experiment program is carried out to study the strength and deformation of lime-soil reinforced with polypropylene fiber inclusions. Three percentages of polypropylene fiber contents, i.e. 0.05%, 0.15% and 0.25% by weight of lime-soil are randomly included into the one-nine, two-eight and three-seven lime-soils. Based on triaxial compression tests, the influences of different reinforced rates, different lime contents, different curing ages and different confining pressures, are studied. From the results of tests, it is shown that the peak deviator stress and shear strength at failure increased at different ranges compared to the conventional lime-soil.

In the present investigation, laboratorial test is conducted to study the evolution law of the fissures of Nanyang expansive clay under wetting and drying cycles. Oven drying method and vacuum saturating method are employed to simulate the drying and wetting process respectively. In order to record the development of fissures, the specimen is weighed and photographed regularly during the drying process. By employing the vector diagram technology to vectorize the fissures photos; the geometric characters of fissures are extracted before calculating the fissures ratios. Study of the regularity of fissures ratios changes proves that: the essential factor that influences the stretching degree of fissures is not water content, but the gradient of water content, which is mainly governed by the spatial distribution of desorption rate, the permeability characteristic of clod and the size of clod. Under wetting and drying cycles, the fissures of expansive clay will develop gradually, and it is mainly represented by the increase of total area and total length of fissures, but the role of wetting and drying cycles is limited, the development of fissures will cease when it comes to a certain degree due to the undersize of the clods. Expansive soil mass will encounter plastic deformation under wetting and drying cycles; this plastic deformation is not relevant to the swell-shrink characteristics of expansive clay, the development of fissures and the damage of soil mass integrity are the direct causes of this plastic deformation; a higher degree of fissures development gives rise to a more significant plastic deformation

Northwest mountain area of Hubei province is landslide-prone area in China. By transportation, utilities, energy, resources and other infrastructure construction greatly being underway, a large number of excavation-type and reservoir storage-type landslide may be triggered in future. The swift establishment of a synthetical classification system for the regional slope/landslide is the basic work for further researching the regional slope/landslide of the development of the law of distribution, deformation & failure mechanism ,space-time forecasts and the corresponding treatment policy. The synthetical classification system can also provide basic achievement data for future in-depth study of the region slope/landslide problem. This article first discusses the establishment of the regional slope/landslide of the basic principles of a synthetical classification system and clear the three most important characteristics of building the regional slope/landslide system. After that, this article presents multilevel block diagram of the synthetical classification system. After in-depth analysis of the typical slope major categories of the synthetical classification system, this article preliminary classifies 19 typical slopes. Some typical engineering examples are listed. The deformation, failure pattern and mechanism of those kinds of slopes/landslides in this region is preliminary analyzed. Some suggestions for analytical method and countermeasures of those kinds of slopes/landslides are put forward.

The horizontal geosynthetic reinforced mattress located on the top of vertical piles is idealized as a foundation beam, while the vertical piles and the surrounding soil are idealized as an elastic spring system. Based on the theory of the Winkler elastic foundation beam and with consideration of the interactional resistances on the interfaces up and down of the reinforced mattress, a deformation equation of the reinforced mattress is established; and its power series semi-analytical solutions are proposed. The presented method can consider the effect of the tensional force of the horizontal reinforcement on the settlement of the composite foundation. The study results indicate that the installation of the geosynthetic reinforcement in the mattress has a contribution to control foundation settlements.

Middle wall is the main bearing component of the double arch tunnel. Non-dense backfill on the top of the middle wall can easily lead to large deformation or collapse of surrounding rocks. In response to this phenomenon, we developed a similar model material and the test equipment and carried out the corresponding destructive model test, by which the evolution process of the collapse was studied. The whole process of collapse has been reproduced by UDEC simulation; and the numerical results are in good agreement with the model test. Collapse mechanism has been derived from the distribution of displacement and plastic zones. Finally, we propose targeted prevention measures which are of reference value for similar projects.

Geological conditions of coal seams in China are very complicated. Existence of a soft interlayer in roof will greatly reduce bolt force and lower safety and reliability of the bolted structure. Regarding the relative position between locations of the soft interlayer in roof and the bolted zone, theoretical analysis and physical simulation have been combined to study the instability characteristics and deformation mechanism of the lamellate roof under mining-influence. Quantitative results of soft interlayer location inside, at the edge of, and outside the bolted zones under different stress conditions are respectively summarized especially the vertical stress, strain and roof bedding separation. To keep the roadway with a soft interlaysr in its roof stable requires not only the basic bolting but also strong supplemental support to ensure a close contact between the bolted zone and its overlying strata, eliminating bed separation and to achieve roadway stability immediately after stress redistribution. A five-grade roadway safety classification system based on the safety factor AQ is established. Then a set of classified enhanced control technologies is proposed, aiming to strengthen bearing capacity of bolts, deformed rock and self-bearing structure of the surrounding rock as a whole. Support effect has been verified by successful application to over 350 000-meter-long roadway of Huainan and Huaibei mining areas. Nationwide application is foreseeable in the near future

The layered interval excavation method for a large span and high sidewall underground cavern is described in detail. Through numerical simulation, its feasibility is proved. A large span and high sidewall cavern construction practice is as follows; detailed large cavern reserved rock clapboard, upper, middle and bottom chamber between rock clapboard parallel excavation, and finally clear the rock clapboard full of this new method of construction of the excavation process. Through numerical simulation, the largest deformation caused by excavation, distribution of plastic zone and tension of rock bolting of two excavation methods are compared. The results show that the new method of rock excavation damage to surrounding rock is small. Finally, the applicable conditions for this new method are pointed. This method has universal significance for similar conditions of underground large cavern construction.

Taking the North Region of Renqiu Ordovician Buried Hill of Raoyang Depression for example, the rock mechanical parameter is defined according to acoustic logging data; the regional boundary loads as unknown condition, the crustal stress of the key well points are taken as constraint conditions, the regional boundary stress is obtained. The geological model, calculation model and mechanical model are established based on it. The distribution rule and characteristic of regional crustal stress are obtained by using simulation in study area. The result shows that the value of crustal stress by numerical simulations is consistent with that of actual measurements. The maximum horizontal principal stress focuses between -61 MPa and -118 MPa in study area, the direction of maximum horizontal principal stress in middle-north part is in west-north, and in south part is in north-south. The minimum horizontal principal stress focuses between -31 MPa and -91 MPa, the direction of minimal horizontal principal stress in north part is in east-north, and in south part is in west-east. Besides, the main crustal stress in the fault zone is smaller than that in continuous strata, the adjacency of fault zone is gradient zone of stresses variation, and the fault zone has an obvious effect on the distribution of horizontal principal stress.

Empirical formula method is one of the most popular-used methods to predict the soft ground deformation induced by tunneling. Various empirical formulae to predict the ground settlement and horizontal movement above shallow tunnels are introduced. Aiming at the asymmetric double-arch tunnel engineering that lies at Jiaozhou Bay in Qingdao, the section ZK2+800.78 which is located in the intersection between main tunnel and ramp tunnel is chosen as a typical cross-section, a three-dimensional model for numerical analysis is established according to geometrical parameters and geological information of the typical cross-section; and dynamic construction process is simulated with finite difference software fast Lagrangian analysis of continua in 3D (FLAC3D). By comparative analysis of the ground settlement and horizontal movement calculated with FLAC3D program and these empirical formulae, the applicability of these methods to predict the ground deformation above asymmetric double-arch tunnel is discussed and evaluated in detail. It concludes that when the strata are in shallow levels, the ground settlement and horizontal movement can be forecast with these empirical formulae approximately. The results also show that the deviation of these empirical formulae increases with the increase of stratum depth. There is a remarkable shortcoming for these empirical formulae that they can only be used to estimate the ground deformation above a single tunnel in a single stratum. FLAC3D has its clear superiority in predicting the ground deformation above asymmetric double-arch tunnel under complicated geological condition.

The common field gob-side entry retaining roofs are divided into three types, i.e. thick immediate roof, thin immediate roof and without immediate roof. Through utilizing the continuous laminate model and considering the factors of the support effect of the coal side in the roadway, the incentives of roof caving, etc., the calculation formulas of roadside support resistance under three kinds of roof conditions are obtained. According to the formulas, the increase bearing ability of coal side and the roof of filling areas benefit to decrease the support resistance of filling body beside roadways. With the decrease of the thickness of immediate roof, the support resistance of filling body increase.The roof collapse’s incentives would vary from different layers of immediate roof. Gravity causes the thick immediate roof’s collapses; and on the other hand, the movement of upper rock layers causes the thin immediate roof’s collapses.

A typical geological model considering soil cover thickness, geological material types for the most harmful covered karst is established. The karst collapse mechanism is analyzed under groundwater fluctuating and rainfall infiltration based on this model. Furthermore, a comprehensive method for karst collapse spatial prediction that involves physical detection, engineering investigation, geological material physical mechanics experiment, numerical simulation and monitor evaluation is proposed and applied to evaluating a karst disaster area in Huangshi, Hubei province. The numerical simulation, which is based on physical detection, engineering investigation and laboratory test of rock and soil, shows that the ground settlement due to softened clay cover caused by rain permeation is larger than that induced by groundwater fluctuating. With reference to the developing tendency of building fissures and ground cracks, the spatial extent of the karst collapse area is distinguished. It is shown that this karst collapse spatial forecast method is feasible; and the prediction results are in good agreement with observations. Therefore, this method can be popularized as a general method for karst collapse prediction in similar engineering.

Uncontrolled blowout is a kind of extreme condition for gas storage cavern operation. Based on one-dimensional insulation flow theory, the analytical solution of pressure drop for salt cavern under blowout is obtained. The stress state, the deformation characteristics and the damage zone evolvement of the gas storage cavern are simulated and studied under three different operating modes, combining with the geological data of Jintan salt deposit. It is shown that the hard interlayers tend to failure before rock salt host; and the three failure regions around the interlayers expand to be sprinkled the whole salt cavern and extend 6-8 m along the radial direction during the unloading phase. The cavern convergence increases with the reduction of the initial internal pressure. There is a large volume loss of 5.02% for initial unloading pressure of 7 MPa. The strain rate of the surrounding salt enlarges to 10-2 s-1, which belongs to quasistatic bound, during unloading phase. The study indicates that the initial internal pressure is the key factor to maintain the storage cavern stability under the runaway blowout. Relatively high operating pressure is suggested to keep in the extreme disaster environment.

During the trial operation of the Three Gorges Project, there are remarkable differences between the deformation of landslides due to different geological conditions and permeabilities. Therefore, besides the geological structure, more attention should be paid to study the regularity of stability variation of different permeability landslides under the condition of reservoir level change. Taking the Huangjingshu landslide at the head area of the Three Gorges as the computation model, the seepage field of 4 landslides with different permeabilities are studied as the water level changes at a steady speed from 0.5 m/d to 2.0 m/d. As the evaluation index, reservoir water influence coefficient, the ratio of water level change speed to permeability coefficient, and stability change ratio is proposed. And the regularity of stability variation is obtained under the condition of permeability and water level change. The results show that when the reservoir water influence coefficient ? changes from -0.107 to -0.322, the stability change ratio ? is the largest; and the ? decreases as ? reduces. When ? changes from-0.644 to -769.231, the ? almost unchanged as ? decreased. When ? changes from 576.923 to 769.231, the reservoir filling had less effect on the landslide stability. When α changes from 0.107 to 384.615, the correlation of ? and ? is not obvious. It has some values for the landslide monitoring and warning in the Three Gorges reservoir area

Wenxiang tunnel for Zheng-Xi Special Passenger Railway has been done a series of research on optimizing the construction method for shallow large-span loess tunnel. According to the field monitoring of ground settlement, vault settlement and primary support stress of the tunnel section before tunnel undercrossing the Lian-Huo expressway. The result indicates that soil settlement and primary support stress can not be controlled very well; and the current construction scheme needs to be reformed since it can not satisfy construction safety requirement. Through synthetical analysis, some optimized methods such as reducing excavation area, increasing excavation steps of pilot tunnel, reserving core soil, quick closure, reinforcing primary support, etc. have been used in construction; and their security and reliability are verified by numerical analysis software fast Lagrangian analysis of continua in 3 dimensions (FLAC3D). From feedback of field implement and monitoring result, the effect of optimized methods is significant; and these methods ensure the undercrossing project implements successfully. These research results have high referential value for analogous project to control soil settlement and protect the safety of neighbouring building facilities

In fluid-saturated porous media elastic waves and electromagnetic fields are coupled due to relative flow between fluid and solid phases. Based on Pride equations, inhomogeneous seismoelectric plane waves are given; and the expressions of energy flux for those waves in fluid-saturated porous media are obtained with the Helmholtz’s method; energy characteristics of inhomogeneous seismoelectric plane waves are discussed. It is shown that the mean energy flux propagates in the plane of the propagation vector and the attenuation vector, the accompanying electric field does not contribute to compressional waves’ flux. When the electrokinetic’s coupling coefficient is set to be zero, the formulations of the energy flux will be become that of energy flux for Biot elastic waves.

The subgrade of Binde Expressway mainly consist of silt and silty clay. The dissipation rule of excess pore water pressure could reflect the reinforcement effect of soil. Pore water pressure gauges were embedded in the test section. By analyzing the changing rules of excess pore water pressure, some conclusions are drawn as follows. When the test section is striked by the tamping energy of 2 000 kN•m，the best hitting number is 8-9 during the first and second passes; the best hitting number is 6-8 during the third pass. The excess pore water pressure of shallow place is higher than that of deeper place; and the excess pore water pressure of shallow place dissipated slowly. The maximum impacting depth is 8-9 m and the effective impacting depth is 6-8 m; the ratio of the effective impacting depth is 0.134-0.179. The maximum horizontal impacting distance is less than 10 m, and the effective horizontal impacting distance is about 5-7 m

The layers of a main tower construction site in Tianjin are mainly clay, silt and silt sand. Two groups of the super-long bored test piles with post pressure-grouting (a total of eight piles) are designed to take bearing behavior test using single pile vertical static load test of compression to master the engineering properties in the main tower construction site. Vibrating wire reinforcement meter and stratified settlement tube are installed to find out the pile side friction and the pile body layered settlement state. After the test, the results of the data analysis show that the pile side grouting can significantly improve the long pile side skin friction; pre-load pressure can enhance the flexibility of the super-long pile and reduce the settlement of the top of the pile in some degree. After unloaded stability, the test pile also has side resistance; the resistance of the upper segment is negative skin friction; and the lower segment is positive skin friction; and the pile body axial force causes the test pile to have some compression volume; that is an important part of the residual deformation.

Because of the superiority in energy scale and modeling prototype stress, soil geotechnical centrifuge have unique advantage in the blasting modeling. Based on the progress for soil geotechnical centrifuge, some aspects in blasting centrifuge modeling such as modeling box, explosion source, centrifuge modeling scale, data collecting and Coriolis effects are concluded, also the known research domain. The development tendency in blasting centrifuge modeling is presented, for example, the measure such as anti-wind should be considered in designing model box, a more accurate method should be adopted to verify the energy scale; micro-explosive source should be more stable and in good quality

The accuracy of three-dimensional stratigraphic models can affect their applications directly. It is an important strategy to use the multiple data coupled modeling to improve the accuracy of the model. Based on analyzing the factors influencing the accuracy of the three-dimensional stratigraphic model and taking geological planar data and drilling data as examples, this paper presents exploratory analysis methods used to automatically detect the deviation between the different types of data; and corrected method which mainly adopts GIS analysis of space exploration and drilling domain influence technology is supplied. The basic idea is described as follows. Firstly, to extract drilling data and geological planar data of a formation interface, and combine them to establish a Voronoi map. Secondly, to detect the deviation of drilling data relative to the geological data by the entropy or clustering attributes of each unit assigned to Voronoi map, and extract the drilling with the largest deviation accordingly. Finally, to modify locally the geological planar data by using drilling influence domain technique. The test results indicate that this method enables to realize the consistent process of data of multiple stratigraphic coupled modeling with high efficiency and relatively reliable result.

Based on the theory of cylindrical cavity expansion which considers the influence of initial radius, and according to the similarity between the mechanism of the critical depth of pressuremeter test and the penetration effect of pile-sinking, the interface of soil heave of pile-sinking with pre-drilling is obtained; and then a simple formula to estimate the range and magnitude of soil heave is derived. The law of soil heave due to initial radius of pre-drilling is analyzed. The initial radius is just the pre-drilling one, so the formula is universal to estimate soil heave which derived in this paper. When initial radius is zero, the formula can be used to analyze general pile-sinking. It is demonstrated that the calculated soil heave is less than the measured value, but more close to it than the FEM result. So a simple and practical formula to estimate the range and magnitude of soil heave for the engineering is given

Tunnel excavation will lead to surrounding rock loose and exert certain load on the structure in the meantime. In the excavation process, the load of structure releases continuously in the stress adjustment process till the structure and rock mass stabilizing. Numerical analysis and model test are carried out to research the load releasing process of the whole section in the construction of ultra-large section railway tunnel. The load fluctuation rules of key points in bench excavation are studied firstly, then concepts of section comprehensive load release rate and difference coefficient of load release that characterizes the state of load release of the whole section are defined; and the load fluctuation rules in the process of construction are summarized via the two parameters. With monitoring of change laws of radial pressure at key points of rock mass in the geomechanical model test, the conclusions obtained by numerical analysis are testified; and the principle that the section must be regarded as a whole is realized to make the study of load release more comprehensive.

The mechanical behaviors of granular materials presented by discrete element method （DEM）based on discrete particle model are closely relative to its numerical specimen. The generation techniques for granular materials specimens has attracted comprehensive attentions with development of DEM in numerical simulation of granular materials. The object of this paper is how to generate a more dense granular assembly using random sequential analysis (RSA) model. For uniform grains, that is to say how to generate more number of grains in given region. Four modified RSA methods are suggested and discussed; numerical practices show that the more dense granular assembly will be generated by sort of coordinates based on RSA.

More and more large-diameter and super-long steel pipe piles are applied to engineering in recent years. But so far , few people have focused on studing their bearing characteristics. Computational theory of ordinary piles is referenced in the foundation design. Vertical bearing and settlement features are simulated for large-diameter and super-long steel pipe piles based on the fast Lagrangian analysis of continua in three dimensions (FLAC3D). Then comparison between simulation results and the results of vertical static load bearing capacity test is conducted and they are complemented and verified each other. The consistent results demonstrate that the method of using the finite difference procedure in this paper to preliminarily simulate the vertical load-bearing characteristics and settlement characteristics of large-diameter and super-long steel pipe pile is feasible. The study shows that the large-diameter and super-long steel pipe pile is a typical end-bearing friction pile. The pile lateral friction resistance changes intricately with depth, which is closely related to the soil characteristics. And the transferring speed of pile axial force depends on the action of pile lateral friction resistance in the different soil. These conclusions are of significance for the reasonable large-diameter and super-long steel pipe pile foundation designed in engineering applications

Rock fractures are assumed as “filled medium”, which enables to treat the rock fractures with or without fillings coincidently. The relationship between the stiffness coefficient, hydraulic conductivity coefficient and the normal effective stress is deduced. Based on the principle of the block element method, seepage-stress coupling model for three dimensional fractured rock mass is built by using the iterative algorithm between the two fields. It treats the blocks as rigid and imperviousness bodies, and the displacement and seepage just mainly happens in fractures. The corresponding program is also written by Fortran language which integrates the stress analysis module and seepage analysis module together. This improves the computational efficiency. Lastly, the Shatuo gravity dam is simulated to verify the proposed method. The most advantage of this model is that large-scaled joints and random fractures are considered; and the preprocessing & post-processing are simple.

With the development of rock engineering, the influence of rock joint development on the project is drawing more and more attention; and network simulation of rock joints is an important means for this kind of problem. Mechanical models can be set up based on discontinuity network models; and then fine numerical simulating work can be carried out, which is an attractive direction in rock mechanics. Based on statistical theory of rock structure, this paper develops its own Visual Basic program for analyzing joint network simulation which can visually represents the mass distribution of joint within the rock, and can creates executable data documents which can be combined with discrete elements software. An example of an underground cavern is analyzed under the condition of static load and earthquake load; and the stress and displacement changes of the surrounding rock of cavern during different periods can be obtained. The studying method and results can be instructive to the research of deformation and failure mechanism of underground cavern surrounding rock and the design of earthquake resistant engineering

Landslide is a major issue endangers personal safety. Detecting distribution of landslide-face is a key factor in controlling landslide. And electrical resistivity tomography (ERT) method is sensitive to interface of different layers, which is used to detect landslide-face. Firstly, four common landslide models are simplified basing on existing landside models. Secondly, systematic numerical simulation is carried out by finite element method about different types of landslides. Response characteristics of landslide-face are obtained using ERT method. Rapid identification of different types of landslide-face is put forward. Then, inversion about different types of landslide-face is done using damping least squares inversion method. Inversion imaging discipline of landslide-face is summarized using ERT. Combined with response characteristics of numerical simulation, anomaly identification features are put forward. At last, ERT method is used to detect landslide in Xili town, Yiyuan city of Shandong province. Distribution of landslide-face is reflected clearly, which shows that ERT method is efficient in detecting landslide-face. And it is laying a solid foundation for conceptual design of landslide controlling