Based on the thought of conservation of energy, using the modeling method of radial slice method, assuming a virtual displacement, a mathematic model of landslide stability calculation is established, so as to provide a new method for landslide stability analysis. Based on the virtual displacement ds, the gravitational potential energy change △U and the friction energy dissipation △W on sliding surface are deduced; and then the landslide stability coefficient is defined as Sc = △W/△U; finally, the mathematic expression of landslide stability coefficient Sc is obtained in two cases of considering groundwater and without considering groundwater. Through the example analysis, and comparing the calculation result with Janbu method. The results show that, without considering the groundwater, calculation results of energy method and Jianbu method is relatively close; and the former stability coefficient is slightly higher; the differential ratio is 0.19%; under the condition of considering the influence of groundwater, the differential ratio is 9.77%; the stability coefficient calculated by energy method is lower; namely, in the energy method, the influence of groundwater on landslide stability coefficient is greater. Based on example 1, the main parameters of the model are analyzed on the sensitivity of the stability coefficient of Sc. Finally, the similarities and differences between the energy method and JianBu method are essentially contrasted.

Soil desiccation cracking is a common natural phenomenon, which has significant negative impacts on engineering properties of soil, and is the direct cause of many engineering geology and environmental geology problems. It is a key to choose appropriate methods for studying soil desiccation cracking behavior. Based on the research work conducted on soil desiccation cracking behavior in recent years, the applied research methods are reviewed and summarized systematically. Meanwhile, the advantages and disadvantages of each method are compared and analyzed; and then the following understandings are obtained: (1) There are generally two categories of research methods for soil desiccation cracking: experimental study and numerical simulation. The experimental study contains two aspects: laboratory test and field test. At present, the former one is more popular. (2) There are commonly two types of specimens are used for laboratory test: slurry specimen and compacted specimen, and the former one is also more popular. (3) There are two types of equipment are usually applied in soil desiccation cracking test: one is used to control the environmental conditions like environmental chamber; and another is used to monitor the development of desiccation cracking and the geometrical characteristics of crack network, including crack image capture device, laser scanner, CT machine, ERT, distributed optical fiber and so on. (4) During the test, factors (i.e. specimen initial condition, size, thickness, mineral composition, environment temperature, specimen-container contact condition and wetting-drying cycles) affecting crack initiation and propagation are well studied by control variate method. (5) Digital image processing technique is efficient to quantify the geometrical and morphological characteristics, showing more promising as compared with other techniques. (6) The field test can reflect the real law of the formation and development of cracking; however, very few information can be found in literature because such field test is usually time and cost consuming. (7) Numerical simulation is one of the important methods to study soil desiccation cracking behavior. Because at this stage there is no uniform understanding of the mechanism on cracking, the related research on this topic is still in its infancy. Based on the current research, this paper puts forward the research focus of this topic in the future.

The indoor shear tests of anchored jointed rock mass under different bolt angles and different normal stresses are carried out to study the law and the shear resistance mechanism of bolt anchoring on shear properties of jointed rock mass. The deformation and stress characteristics of anchored jointed rock mass under the action of normal and shearing force are explored; the shear deformation law of the jointed rock mass before and after anchoring is compared and analyzed; and the effects of bolt angle, normal stress of the joint surface and other factors on the shear resistance of jointed rock are discussed. The experimental results show that the shear strength of jointed rock mass can be greatly improved by bolt anchoring as the increase of the cohesive force and internal friction angle after bolting; the bolt angle has significant influence on the shear strength and shear deformation of the anchored jointed rock mass; and the larger bolt angle is helpful to mobilize the shear resistance of the bolts. The shear-displacement curves of the jointed rock mass have three segments after anchoring, i.e. the elastic stage, the yield stage and the plastic deformation stage. The shear strength of anchored jointed rock mass is improved with the increase of the normal stress of joint plane under the same bolt angle. It is found that the yield failure of bolts in the jointed rock mass occurs mainly in the section near the joint plane; and the local damage of the rock material occurs near the joint plane due to the lateral compression of the bolts.

Considering the layered characteristics of mining floor, the floor strata are equivalent to layered semi-infinite plane. A stress calculation model of multilayer floor strata is proposed based on the transfer matrix method. The corresponding calculating program is written by Matlab to calculate the stresses of multilayer mining floor strata. And the plastic zone of mining floor is determined by the Mohr-Coulomb yield criterion. The proposed model take into account the rock lithology and its composite structure of floor strata, so the calculation result of failure depth is more closer to the actual situation than the traditional method. Then different calculating models are established to study the influence of rock properties of the floor strata on the stress distribution and failure characteristics of mining floor. The results show that the hard rock has the reducing and dispersing effect on the abutment pressure. The reducing effect can cause lower stress in the deep floor strata, and inhibit the failure of mining floor. The dispersing effect can expand the influence scope of stress in underlying strata, and widen the failure scope of underlying strata. In soft rock with low load-bearing capacity, will aggravate floor stress concentration, so as to increase the scope and the depth of failure zone in the floor strata.

To investigate the mechanical properties of shale under different confining pressures and different strain rates, the triaxial compression experiments of Longmaxi Group shale samples are conducted under different confining pressures and different strain rates. The experimental results show that the confining pressure and strain rate affect obviously elastic modulus, peak strength and fracture morphology of the shale. The elastic modulus and peak strength increase with the increase of confining pressure, the increase of peak strength is significantly greater than thaengtht of the elastic modulus; and the peak strength showed a linear increasing trend. At a low confining pressure, elastic modulus and peak strength gradually increase along with the inclining of strain rate from low to high; the relationship between the two and the strain rate can be described by a biquadratic polynomial. With the increase of confining pressure, the effect of strain rate on the shale is gradually weakened; at a high confining pressure of 50 MPa, the phenomenon of the compressive strength and elastic modulus increase with the increase of strain rate is terminated. Under condition of low confining pressure and high strain rate, the shale is mainly split shear failure; with the increase of confining pressure and the decrease of strain rate, the failure mode would change from split shear failure to single shear failure; and then gradually transits to a ductile fracture. The results of the test have important guiding roles in establishing the mechanical parameters of shale and designing the fracturing program.

This paper proposes a method for determination of shear strength based on stress concentration factor by investigating the distribution regularity of stress concentration factor in the shear plane and analyzing the curves of shear stress-shear displacement. Laboratory large-scale direct shear tests are conducted on the specimens from clay layer with breccia along Wuhan metro line 6. the variations of shear strength parameters of the soil layer with the stone content variation are determined. Through comparing this method with procedures in codes, the feasibility of this method are discussed. The results show that the stress concentration factor K0 partly reflect the shear strength of the soil; the cohesion of clay containing breccia approximately increases linearly with the increase of stone content, which is consistent with the existing research results. This method for shear strength based on stress concentration factor, can be used as an effective way to study soil strength characteristics.

Based on the shallow translational slip model of soil slopes under seepage parallel to slope surface, the rectangular frame protection unit is taken as a research object, the relationship between soil skeleton and the interaction and soil shear strength of nonlinear characteristicsthe are analyzed under the lower stress level. It is proposed that the three failure modes including the direct shear sliding mode and retaining passive failure mode which happened in rectangular frames, and their threshold lsp reflecting vertical distance. The factor of safety for the shallow stability of soil slopes protected by rectangular frames under the influence of seepage parallel to slope surface is established; and the checking method of protection engineering which aimed the factor of safety and frame structures strength is also presented. The analytical results show that the threshold lsp is determined by frame structure thickness, h, and increases with increasing h. Among the three modes under the influence of vertical distance, lv, the lv under the modes Ⅱcomparing to mode Ⅰ, have more significant impact on the factor of safety, and if failure mode was determined falsely will induce dangerous result due to highly estimating resistance force from frames. In the condition of satisfying the factor of safety for shallow stability of soil slopes and the frames structure strength, the type of horizontal window with depth cross comparing to vertical window with planar cross can save more masonry amount.

A roughness discrete fractures network(RDFN) model is proposed considering the complex and roughness geometry distribution of discontinuities in jointed rock masses. The digital image processing technique is firstly used to generate RDFN images using Matlab code. Then a RDFN model based on particle flow code(PFC) is established and the corresponding mechanical behaviors under uniaxial compression, such as elasticity, strength and failure pattern, are studied and compared with the traditional linear discrete fractures network (DFN) model. The results show that the elastic modulus of RDFN model is lower than that of DFN model. The peak strength of RDFN model is higher, and residual strength is lower. Microcracks in DFN model mainly coincided along the linear joints and partial intact rocks are fractured. The failure pattern of RDFN model is, however relatively much more complex with more fractured intact rocks after peak strength.

Based on the complex variable method, and the stress boundary conditions on the surface and the excavation boundary, the analytical solutions of the stresses and displacements of a shallow circular tunnel under the gravity and tectonic stress are deduced. Introducing the , which reflects the level of the horizontal stress on the ground surface, the solution become general, suitable for the case whether the horizontal stress on the ground surface is zero or not; and the correction can be verified by the ANSYS software. The distributions of the stresses and displacements field are analyzed. The results show that tangential tensile stress may appear on both sidewalls when the surface horizontal stress is non-zero; and the value of the tensile stress increases with the horizontal stress. Meanwhile, the vertical displacements on the surface, the vault’s upward deformation, the sidewalls’ extrusion deformation are influenced greatly by the surface stress as well.

The failure process of rock containing single fissure is investigated under laboratory environments. Integrated with particle imaging velocity(PIV) and strain measurements during experiments, displacement vector of samples during failure process is identified and moreover the stress on the surface of samples is calculated based on finite element(FE) method. The k-value, which is defined as the ratio of concentration stress to peak stress of samples during experiments, is proposed to identify the stages of deformation and failure process of rock containing single fissure. Then the stress field characteristics at each stage are analyzed. The results show that: at first, k-value increased and remained constant. Then k-value fluctuated and increased dramatically with the increasing of axial strain. Several important stress thresholds are acquired according to the variation regularity of k-value; the closure stress σcc , the initiation stress σci , the damage stress σcd , and the values of them are 0.13-0.17, 0.48-0.59, 0.80-0.92 times of peak stress σp respectively. The k increased dramatically after fluctuated; macroscopic cracks are observed in the region where stress concentrated. Macrocrack distribution areas are consistent with stress-concentration areas. This study will help people to understand the stress field variation of cracked rock and provide a new way to divide the deformation and failure process of cracked rock.

Nowadays the deformation monitoring of roof subsidence of mine roadway, tunnel, etc., is one of the indispensable means for engineering security. The existing linear distributed fiber optic monitoring technology is low sensitivity. Based on the distributed optical fiber sensing technology, further research is made on the form of the layout of the fiber. We put the fiber along the longitudinal vertical plane layout of roadway roof into sawtooth shape, build the corresponding calculation model, give the layout parameters and obtain the monitoring accuracy and the measurement range(AV6419). The test results show that when we change the linear layout into sawtooth layout it can not only meet the requirements of large-scale field measurement of distributed information capabilities of distributed optical fiber sensing technology, but also realize the purpose of monitoring the radial deformation of the roadway (such as roof settlement) through the arrangement of axially distributed optical fiber in roadway. Besides, this model’s sensitivity will have a substantial increase, so as to provide a new method and ideas for application and promotion of distributed optical fiber sensing technology based on BOTDR.

To investigate the effect of bedding on failure mode, elastic modulus and strength of rock with high porosity under different stress conditions, several groups of triaxial tests on specimen with different bedding angles are conducted with pre-hydrostatic compression and axial stress increasing mode. The results show that the anisotropic quartz sandstone showed different characteristics of deformation damage under different stress conditions. With 30 MPa as dividing line of confining pressure, shear failure mode happened in the range of low confining pressure and as the confining pressure increased, fracture surface turned slope to horizontal and is influenced by the bedding. In range of high confining pressure, under the influence of bedding, failure mode could be divided to shear yield and volumetric yield. As the confining pressure increased, the number of newly closed crack reduce, the effect of anisotropy to elastic modulus showed reducing trend and the average increasing rate of Young’s modulus decreased. Young’s modulus of all specimen declined at bedding angle = 60°. Strength curves of different specimen with different bedding angles showed U shape. The minimum compressive strength in range of 0-20 MPa confining pressures showed at the bedding angles = 30°; while in 30-60 MPa transferred to = 45°. Feature coefficient of compressive strength for quartz sandstone with different bedding angles decreases as the confining pressure increases, and keep constant as confining pressure is over 30 MPa.

Recyclable soil nailing is formed by welding a steel wire with a certain height on the optimum diameter steel pipe. The recyclable soil nailing is connected with the specific length by special connection structure and screwed into foundation pit slope by using the rotating construction equipment. The processes of the described above form a new type of assembly recoverable soil nailing. The traditional soil nailing stress mechanism relies on the cohesive force or friction between grouting anchor solid and soil. The new type of soil nailing changes the stress mechanism into friction between soil and steel tube interface and extrusion force between soil mass and the wire ends. The working mechanism of new type of soil nailing is obtained by field tests, the optimization of numerical simulation and field application tests. The new type of assembly recyclable soil nailing adapts to construction industrialization trend, reduces geological environment pollution and realizes building materials to be recycled. Therefore it has obvious engineering value.

By performing laboratorial shield tunneling simulation tests, the effect of shield tunneling on the deformation of underground pipelines is studied under the condition of three kinds of relative positions between tunnel and pipelines, namely vertical, heterotropic, and parallel. With ongoing construction of subway in Hefei region as engineering background, the laws of settlement, deformation, and relative angle of the underground pipelines are mainly researched. Results show that the second disturbance is more likely to induce settlement in soil, which exerts a greater influence on the displacement of underground pipelines. The range where the pipeline deforms along the tunnel axial direction is found to be different from that along the tunnel radial direction during shield tunneling, showing a greater induced deformation of underground pipeline along the radial direction than that along the tunnel axial direction. After the tunnel excavation, the earth pressure under the pipelines change, and an area of load free appears below the middle section of the pipeline, which gradually reduces the earth pressure while increases the additional stress under the two marginal sections of the pipeline. The conclusions can provide a reference of damage controlling for the prediction of the effect of shield tunneling on the underground pipelines.

Replacement rate is one of the key indicators for designers to determine the composite foundation of CFG piles. After determining the pile length according to the distribution of soil layer, the choice of replacement rate is the basis of vertical structure system decision-making according to additional load for target. At present, we have a lack of common knowledge and understanding of the mechanical properties of composite foundation affected by additional load under different replacement rates. Two centrifuge model tests with the same additional load and reinforcement depth and different replacement rates have been carried out to study the change law of the pile axial forces, pile side frictional resistances, pile-soil stress ratio and foundation settlement of the composite foundation during loading process. As the increase of the replacement rate, the test results show that: (1) The axial force of CFG pile is reduced; and the position of the maximum axial force is up along the pile. (2) The positions that the direction of pile side frictional resistance changes or that has the maximum negative frictional resistance in the upper part of the pile are also up along the pile; and the rate of change of the latter is reduced. The maximum positive frictional resistance in the lower part of the pile is obviously reduced. (3) The pile-soil stress ratio is reduced and its reduced rate along the depth direction in deep soil is decreased. (4) The foundation settlement and the ground surface settlement are effectively decreased; and the surface settlement changes linearly with the load; and the composite modulus of CFG composite foundation is improved.

As more and more high-dam hydropower and high head pumped storage projects have been constructed in China, the rock foundation of high dam and high pressure water diversion system generally sustain high water pressure and hydraulic gradient. In this circumstance, not only nonlinear flow is prone to occur in rock seepage; but also accompany with leakage, seepage failure and water-inrush risk. This study experimentally investigated the nonlinear flow characteristics of broken granite rock in Yangjiang subjected to a wide range of confining pressures (1-30 MPa) through triaxial cell test system. The characteristics of nonlinear flow in broken granite rock have been elucidated; and its representation methods have been investigated. The results show that nonlinear flow occurs in the broken granite with the increasing hydraulic gradient, while the flow nonlinearity decreases with the increasing confining pressures. Combined with the cracked morphology of broken granite and the magnitude of the permeability, three possible causes triggering the nonlinear flow have been elucidated, i.e. inertial effect, seepage failure and solid-water interaction. Further, the Forchheimer and Izbash equations have been adopted to characterize the nonlinear flow, respectively, which both provide excellent description for the nonlinear flow in broken granite. The nonlinear coefficient of Forchheimer equation experience positive and negative values during the loading process, which is possibly ascribed to the closure and extension of the cracks in the broken granite. The power-law function between the nonlinear coefficients of Izbash equation has been developed by relating them with confining pressures. The results may prove useful in proper understanding of fluid flow through fault zone and compressive zone under high water pressure and hydraulic gradient.

Directional simulation method is proposed to calculate the small probability of slope failure. Algorithms of directional simulation and wedge safety factor are introduced and programmed. The direction simulation results and the importance sampling respectively, compare the calculation results with the subset simulation analysis. The results show that the directional simulation method can be used to calculate the small probability of slope failure as the same with subset simulation method. And directional simulation method can get enough accuracy by a small number of sampling, which means more efficiency than the other two methods.

It is a new attempt to use the anchor reinforced vegetation system (ARVS) to constrain the deformation of expansive soil. To investigate the constraint effect of ARVS on the deformation of expansive soil, water immersion model tests with and without protective methods are performed adopting medium expansive soil in Nanning, using the simplified indoor ARVS device. The deformations of expansive soil under different constraints are analyzed; and then the transfer law of expansion force is verified by finite element method according the force conditions of two different models. The results show that: with the constraint of ARVS, the deformation of expansive soil can still be divided into three stages; the ARVS can reduce the amount of expansion of expansive soil significantly; but the constraint effect of ARVS on the deformation of expansive soil before and after planting vegetation, and after planning vegetation the deformation of expansive soil can quickly reach the stable stage; the expansive force acting on the high performance turf reinforcement mats (HPTRM) firstly is transferred to the earth anchor by the anchor plate, and then the expansive force is transferred to the soil layer by the earth anchor. Anchor reinforced vegetation system provides a new method for the protection and treatment of expansive soil slope.

A new incremental transfer model of pile-soil interaction is presented on the basis of the disturbed state concept(DSC), and the load transmission mechanism is analyzed as well. According to the result obtained with Matlab, the influence law of the model parameters to the relationship between and is analyzed. It show that, the parameter has a decisive influence on the pile-soil interface strength, reflect the concentration degree of the pile-soil interface element strength distribution, which means that the hardening, softening and elastic plastic characteristics of pile-soil interface can be described by choosing the proper parameter. The parameters and have relatively smaller influence on interface strength, since the change in the parameters only has effect on the maximum value of shaft resistance. The greater the parameters and , the greater the extreme value of the lateral frictional resistance, but it has little influence on the shape of the curve. The parameter can affect both the strength interface and curve in a certain way, the greater the peak intensity of , the higher the interface strength, the smaller the interface displacement corresponding to the peak of the lateral frictional resistance. Due to the fact that the theoretical curves agree well with the curves from static loading test, it has a certain guiding significance on engineering practices.

Alternating load damages fracture conductivity. Alternating load is caused by stress shadow effect between artificial fractures during the process of shale-gas well multistage fracturing or caused by gas extraction and stop production during the period of production. Ceramic proppants with different thicknesses are tested via the DL-2000 diversion tester under cyclic loading to study deformation and seepage characteristics of proppant. The results show that with the number of cyclic loading increasing, elastic strain is basically stable, the plastic strain continues producing. Plastic strain is the basic reason of the decreasing permeability. The trends of plastic strain along with closure pressure coincide well with that of permanent permeability loss. Elastic strain and recovery permeability increase with closure pressure increasing. Elastic strain decreases with sand thickness increasing; but recovery permeability has no significant change. Along with the thickness of sanding increasing, fracture stress sensitivity reduces; particle breakage degree decreases; so increasing sanding thickness can decrease crack width loss and permeability loss; and then reduce the harm of fracture conductivity caused by cyclic loading.

Geological CO2 storage(GCS) is a technology for carbon emission-cut, by injecting anthropogenic CO2 for long-term storage into underground aquifers or depleted hydrocarbon reservoirs. Because of the uncertainties induced by geological site condition and human activities, injecting CO2 into the reservoir may lead to leakage through abandoned wells, faults, fractures, and the "weak zones" in the caprock. A comprehensive review on GCS-associated leakage and safety issues was made, based on an extensive investigation of both domestic and international literature. Leakage from a wellbore may occur through the annulus cement, well plugs or the fracture zone of the contact rocks, due to chemical corrosion and/or mechanical failure. Injecting massive amount of CO2 into reservoirs may induce fractures in the seal, activation of potential faults and their slip. Leakage of CO2 along faults/fractures is mainly affected by factors such as the effective permeability and fracture aperture. Leakage through the caprock can be seepage, diffusive or one that occurs through fissures. The diffusive leakage through the caprock should not be neglected when assessing leakage for large-scale GCS projects. Leakage of CO2/brine into the overlying aquifer causes its variation in geochemistry such as a lower pH, higher salinity, more ions, or even the presence of free CO2. Monitoring of pressure and sampling in the overlying aquifer can be effective to identify CO2 leakage from the underlying reservoir. Research on GCS-associated leakage is very limited, with a particular lack of quantitative studies in China.

centrifugal tests with 20-step normal and reverse faulting were conducted to investigate the deformation characteristics and rupture propagation of overburden saturated clay. The results show that, duo to normal fault, several paralleled tensile ruptures appear on surface. Normal fault rupture gradually shifts from dip slip direction toward to the hanging wall as the throw increases. Ruptures develop toward to the hanging wall and mainly appear near fault rupture line. Whereas as a result of reverse faulting, smaller and less ruptures appear in hanging wall, relatively far from fault rupture line. The displacement increases as the throw increases. Ground below fault rupture line remains stationary during faulting; but above fault rupture line it moves compatibly with the hanging wall. The peak slope increases as the throw increases. The peak slope position shifts toward to the hanging wall for normal faulting and to footwall for reverse faulting. The reverse faulting induced impact region is larger than that by normal faulting.

Marine sediment soft soil is one kind of typical structure soil with high sensitivity and low bearing capacity, widely distributed in the coast area of China. The In-situ mechanical properties of soft soil site are tested in the depth range of 29 meters through self-boring pressuremeter test. The in situ horizontal stress, critical plastic stress, undrained shear strength and shear modulus, etc. are obtaind. The curves of pressuremeter test show four stages of soil, including stress balance stage, elastic stage, plastic stage and failure stage. Unloading reduces the effective stress of soft soil significantly before the last stage; much attention should be paid to the stability of soft soil during unloading process in engineering practice. Based on the obvious nonlinear characteristic of soft soil’s shear modulus, it is more reasonable to get shear modulus by using nonlinear analysis method. On the basis of the experimental results, using fitting methods to set up empirical formulas of in situ mechanical properties and critical plastic stress varying with depth, so as to provide a reference instruction for the determination of the parameters in engineering.

The degradation mechanism and time-dependent failure mechanism in high steep rock slope are investigated in the cold region. Experiments of triaxial compression and triaxial creep are carried out on the quartz sandstone samples experienced different freezing-thawing cycles. The difference of mechanic property and failure model under the action of short-term stress and long-term stress are focused on. Experimental results show that the freezing-thawing action made little effect on mechanical properties of sandstone under short-term stress. The conventional mechanical parameters and acoustic emission (AE) phenomenon just decreased slightly with the increase of freezing-thawing cycles. However, the freezing-thawing action made great effect on mechanical properties of sandstone under long-term stress. With the increase of the freezing-thawing cycles, the creep mechanical parameters changed with increasing freezing-thawing cycles obviously. This is because that the freezing-thawing result in the fatigue damage of the crack wall and the particle in the crack wall can deform sufficiently, causing the obvious creep properties. The long-term reduction factor, which can predict current situation accurately, is proposed for symbolizing the ability of resisting to long-term load of sandstone. In addition, the failure patterns of rock under the action of short-term and long-term stress after different freezing-thawing cycles both are shear failure. But the broken way of rock under the action of long-term stress developed gradually from single oblique cutting surface to X-shape conjugate shear surface with increasing freezing-thawing cycles and the broken degree is more serious. The result is of great significance for the whole life cycle assessment of major projects in highland and cold region.

The points in two scanned point clouds are not repeated and unrecognizable; all monitoring points must be computed by some methods that consider the point cloud characteristics, such as the gravity center method, fitting method, model difference method and so on. These existent methods are sometimes limited in practical applications because they either get very few deformation points or require continuous and smooth surface. This paper proposes a new method that can directly calculate the deformation based on scanned point clouds during two periods through following processing: segment point clouds of deformable object; transforming coordinates and projection, dividing the point clouds into grids; computing and sorting the shortest distance; averaging median of sorted distance; inversing transformation deformation. Simulated and field experiments show that the proposed method possesses following characteristics: non–contact measurement, no need for data preprocessing, strong anti–noise, monitoring point pairs with high–density, surface–independent and mm–level monitoring accuracy within 150 meters.

Spacing of discontinuities formed in the same tectonic stage is believed to obey a negative exponential distribution. Single factor clustering method according to orientation is most commonly used. However, the probability density function of spacing in one set of discontinuities clustered only based on orientation may be irregular, even exhibiting no rules. To overcome the deficiency, this study proposeds a new double-factor clustering method(NDCM), considering spacing distribution and orientation of discontinuities during clustering. The initial clustering result and membership values are obtained based on the fuzzy K-means. Through redistribution of the discontinuities whose membership values are low, this method adjusts the probability density function of spacing to make it more closely obey a negative exponential distribution. To obtain the clustering precision of NDCM, a numerical model calculation which contained two and three discontinuity sets has been made and the correct set code of every discontinuity were known. The model has been calculated by the two methods. Comparison results show that NDCM has an obvious advantage over fuzzy K means in clustering precision. About 6% promotion occurs in precision clustered by NDCM compared with fuzzy K means.

This article aims to investigate whether coal mining ubder the Cretaceous and Jurassic porous sandstone aquifers causes settlement of the upper aquifers due to dewatering. Triaxial compression drainage tests on four kinds of particle grades of porous sandstones are conducted under different conditions i.e. fixed axial pressure, variable confined pressure and pore pressure. The axial deformation characteristics of samples with the decrease of pore pressure are attained, from which formulas are derived for the settlement of lower part of aquifer with a certain thickness due to dewatering. The results show that: (1) The decrease of pore pressure in sandstone will produce the nonlinear axial shrinkage deformation; and the greater particle grades of sandstones, the greater axial strain induces. (2) The axial deformation only relates to initial pore pressure u0 and pore pressure gradient ?u but does not depend on confining pressure σ3, and the greater ?u or u0, the greater axial deformation will be produced as u0 or ?u is constant. (3) The proposed dewatering settlement formulas of sandstones aquifers can be used in calculating the dewatering settlement with a variety of sandstones; so a new method for calculating the drainage settlement for sandstone aquifer within a certain range is provided.

The basic features of the mud surface settlement and the sedimentation rate under the deadweight in heterogeneous dredger fill soil with initial varying sand-mud ratio and initial water content are acquired by means of large size settlement column tests, and the variation of the density profile of the sample is obtained by combining with stratified sampling method. The results show that: heterogeneous dredger fill soil and particles settlement under deposited deadweight have a closer relationship with the initial moisture and sand contents; the higher initial water content, the greater the settlement, the faster the settlement rate; the more sand, the greater settlement. The settlement increase significantly as the sand-mud ratio grows, but the settlement declines as the sand-mud ratio increases when sand-mud ratio is more than 20%; and the lower the initial moisture content, the more obvious the phenomenon. At higher initial moisture content, the settlement-time curve of each sample can be basically divided into three stages; and nonlinear characteristics are obvious in the stage II. As the initial moisture content declines, the three stages and nonlinear characteristic in the settlement - time curve gradually disappear; the lower sand-mud ratio, the more significant linear characteristic in settlement-time curves. Density profile along the height changes a lot at the high moisture content and high sand-mud ratio; and it presents a step-change feature; while it gradually varies linearly as the initial moisture content and the sand-mud ratio declines. Initial moisture content and the sand-mud ratio effect the grain distribution, higher the initial moisture content and the sand-mud ratio is beneficial to (>0.075 mm) sedimentation of particle size greater than 0.075 mm; the higher the sand-mud ratio, the more particle size less than 0.005 mm at the bottom, which shows the feature of group settlement.

To investigate unsaturated shear strength of compacted expansive soil within the entire range of moisture and density state, the unsaturated direct shear tests are conducted on Jingmen expansive soil associated with 38 types of moisture and density state combinations. The distribution of shear strength are obtained with respect to moisture state varying from air-dry to saturation and density represented by void ratio ranging from 0.539 to 1.089. Conclusions are as follows: (1) Strain-softening phenomenon is observed in shear for most samples. In contrast, strain-hardening phenomenon is observed in shear only for the lower-density and higher-moisture state combination. Stress plummeting phenomenon is observed in shear for the higher-density and lower-moisture state combination. Plastic deformation capacity of the soil samples is improved by increasing moisture under the same density or improved by decreasing density under the same moisture. (2) With the moisture increasing from air-dry to saturation, the unsaturated shear strength and total cohesion increase and then decrease, which can be called the peak effect. (3) Unsaturated shear strength, total cohesion, and total friction angle all decrease with decreasing density, which can be called the density effect.

In order to study the capacity characteristics of surrounding rock system, laboratory model tests with different sizes and embedded depths of anchorage are conducted. The results show that the contact area of anchorage and surrounding rock first reaches its limits; the anchorage has small deformation; the stress gradually spreads to surrounding rock; the deformation occurs on the surface. Eventually, the anchorage has catastrophe displacement; and the cracks appear on the surface of surrounding rock. According to the load-displacement curve of anchorage and rock surface and internal additional stress, the bearing capacity has been studied. Because the III surrounding rock does not satisfy the similar ratio, the numerical method has been proposed for distortion correction. Consequently, for the similarity model test of original geological model, the allowable load is 30f where, f is the design load, and the ultimate load is 50f. The research results can provide reference for the design and construction of similar projects.

The critical strength parameter pairs are calculated by reversely using the upper-bound limit analysis with polar slice method, which are treated as fitting data to obtain the seismic global limit response surface. The seismic global limit response surface is then regarded as kernel function and applied to Monte Carlo simulation to obtain the seismic failure probability and corresponding reliability index of reinforced slope with prestressed anchor cable, which avoided redundant and nested calculations by directly using the upper-bound limit analysis. In addition, this method is applied to a typical slope case which is reinforced with prestressed anchor cable. The results of limit response surface based on “the most adverse sliding surface with mean parameter” is calculated and compared with ones of global limit response surface. The results show that the failure probability of global limit response surface is larger than the other one; therefore, the method based on specific limit response surfaces may tend to be unsafe. Moreover, the influence of anchor parameters on seismic failure probability and the relationship curve between failure probability and reliability index are analyzed respectively. This method gives consideration to both the global variation of parameter space and efficiency of computation, so as to provide theory references for the seismic design of reinforced slope with prestressed anchor cable based on reliability index.

The geometrical structure and mechanical characteristics of backfill body are factors influencing the quality of filling material. In this study, similar simulation tests were conducted to investigate flow sedimentation law of filling slurry; uniaxial and triaxial compression tests on backfill body samples were carried out to reveal the structural characteristics and strength distribution law of backfill body, and to capture the deformation characteristics and failure mode of uneven backfill body samples under different confining pressures. The results show that: (1) Two boundaries and three areas of coarse aggregate, fine aggregate, cement-tailing exist in backfill body in stope. The strength of backfill body samples has an “S” distribution of diminution-enlargement-diminution along the flow direction of filling slurry. (2) Stress-strain curves of backfill body samples under triaxial compression are composed of five stages of the compaction, i.e. the elastic, the plastic, the post-yielding, the strain softening and the residual stress stages. The strength of backfill body samples in the same area increase with the increase of confining pressure. The strength of backfill body samples in different areas under the same confining pressure is in the order as cement-tailing area > fine aggregate area > coarse aggregate area. The cohesion of backfill body samples in different areas is in the order as cement-tailing area > fine aggregate area > coarse aggregate area, and the internal friction angle is in the order as coarse aggregate area > fine aggregate area > cement-tailing area. (3) The quantity of macro-failure cracks of backfill body samples is on the up-trends as the confining pressure increases, the main macro-failure modes are shear failure of single ramp, tension-shear failure, Y-shaped shear failure. The results can provide theoretical basis for the design of the amount and position of drill holes for filling, also provide theoretical basis for stability analysis of filling material.

The spatial variability of soil properties in reliability analysis is of great importance, of which the inherent variability of soil can be analyzed through random field theory by determination of coefficient of variance and scale of fluctuation. In this paper, efforts have been devoted to the fluctuation function method to determine scale of fluctuation. Meanwhile, factors such as trend removal method, sampling spacing and sampling range are analyzed based on tip resistance from cone penetration test(CPT), modeling as a random field. It turned out that, as to analyzed data in this paper, if more than one peak point exists when employing the fluctuation function method, the first peak point should be taken as the scale of fluctuation of the soil, which has never been analyzed before. As to affecting factors, some very useful conclusions are obtained. Firstly, selection of the trend removal method should be based on the condition of soil properties; and the quadratic trend removal method is suggested if nonlinear method adopted. Secondly, the scale of fluctuation increases with increasing of sampling spacing when the number of CPTs is large. Last but not the least, as to a same sampling spacing, the scale of fluctuation decreases with increasing of the number of penetration tests; but such difference gradually becomes not obvious for large sampling spacing.

The saturated and softening creep characteristics of gypsum rock have important impacts in the safety evaluation of gypsum mine goaf. Taking Jingmen gypsum mine as the research object, the saturated and softening creep characteristics of gypsum rock are analyzed by carrying out single sample step by step increment load experiment in natural or saturated conditions; the constitutive relation of gypsum rock has been described by Nishihara model. The results show that the total creep deformation of saturated states is large than the natural; the average strength (11 MPa) of saturated samples is 0.54 times of the natural samples (21.5 MPa), the average long-term strength of saturated samples (10 MPa) is 0.49 times of natural samples (19.5 MPa); using the Nishihara model to fit the creep curve and analyze the creep parameter; the fitting results show that the creep parameter E1 is 0.1-0.5 times of natural sample; η1 is 0.2-0.7 times; E2 is 2-10 times. The above results indicate that the creep characteristics of saturated samples are more obvious than the natural ones. By analyzing the mechanism of creep characteristics of water-softening gypsum rock, we can draw the conclusion: the water-softening of gypsum rock includes the hole-pressure effect under hydrostatic pressure in physical layer aspect and recrystallization in chemical layer aspect. The resulting findings can provide basis for safety evaluation of gypsum rock goaf, which has important actual engineering significance.

According to the need of laboratory study of the generalized stress relaxation characteristics of rock, an experimental system of uniaxial tension servo control, which is based on stress feedback take hardware devices as basis and transforms data recording and servo controlling to achieve the stress feedback method, is developed. The advantages of the uniaxial tensile test system are as follows: (1) The system can realize the stress feedback, except carry out the traditional displacement control and stress control of the load alone, also stress-strain linear combination of servo control. (2) The measurement system and control system are realized by hardware rather than computer software; the structure is simple and compact; the reaction time of the system action is short; the performance is stable and reliable; the space of upgrading is large. (3) The control and monitoring data use simulate signal transmission and the test process control and data acquisition accuracy are higher. (4) By using high strength adhesive, the specimen is in the state of tension; and the stress state of rock mass can be simulated in real engineering. Using this system, the generalized relaxation test of tage tuff under tensile stress has been accomplished, and the test results show that the device has good practicability and reliability, so as to provide a new method and means for studying the mechanical properties of generalized stress relaxation under the action of tensile stress of rock in engineering practice.

The aim of the study is to analyze stability of slope under the action of bolt using the principle of minimum potential energy. Forces of unit sliding body are projected on sliding direction of slope to solve shear stress of supplying shear potential energy. Through static equilibrium equations in the direction of the imaginary displacements of unit body, the analytical solution of shear stress distribution on the sliding surface is obtained,and a model for calculation of shear force is constructed. At the same time, the line strain energy and bending strain energy of the bolt are considered when the total potential energy function of the slope is established; and an improved stability analysis method based on minimum potential energy for the is proposed under bolt. A comparative analysis between the traditional algorithm and proposed procedure is made via a case study. Bolt parameters impact on the safety factor of the slope is examed. Research shows that the proposed calculation method is feasible and reasonable; bolt bending strain energy can be neglected when solving slope safety factor; bolt vertical spacing, length, anchorage angle, the anchoring force and distance of the first row of bolt from the ground have significant influence on of safety factor; and the influence of bolt stiffness level on the slope safety factor is low. With the increase of bolt length, curve of slope safety factor shows variation tends to increase first and then stable; when the angle of anchorage is 22°, the safety factor of the slope has the best value.

The red mud leachate is strong alkalinity. Firstly, the red mud leachate are analyzed, and simulated by alkali solution; the clayey soil samples from Shanxi province are used in this research; the physical properties of soil is studied under the effect of alkali solution further corrosion; the corrosion time effect is analyzed especially. Then the intensity variation of red mud reinforced sample, which is reinforced by using cement (or fly ash), is analyzed further under long-term corrosion. Study results show that the intensity change of the reinforced sample with different curing times, which is in immersion of alkaline solution, mainly occurred in the early stage of the whole immersion process, and that the strength of the reinforced sample tends to be stable under the combined action of a long-term condensation process and corrosion effect, namely unconfined shear strength of red mud reinforced sample has no obvious attenuation in corrosion later stage of alkaline solution; and it is feasible for red mud reinforced by cement and fly ash.

The stability of trench face of diaphragm wall is the most critical question in diaphragm wall construction quality and construction safety; and collapse accidents of trench face occur now and then due to inappropriate protection measure. The paper first analyzes the instability mechanism and form of trench face, and sums up both the disadvantages and advantages of every kind of anti-instability reinforcement measures for trench face. The paper also puts forward the suggestion value of rational reinforcement width and the principle of certainty of rational depth of deep mixing pile. Then, it summarizes the application conditions of every kind of stability safety factor calculation method of trench face under the terms of slurry protection, and discusses the rationality of every kind of safety factor value, and gives the recommended values. Finally, it provides the stability safety factor calculation method and decision criterion under the terms of mixing pile reinforcement. Through a number of engineering practices, the reliability of stability safety factor calculation method and stability decision criterion of trench face and both the rationality of depth as well as width under the terms of mixing pile reinforcement have been verified.

There are three different failure mechanisms of multi-bench retained foundation pit with different widths of the bench, i.e. overall overturning failure, mutual-effect failure and separate failure. The separate failure mechanism is studied with shear strength reduction method; and the influences of three main factors, i.e. soil strength; the length of first retaining structure L1 and the length of second retaining structure L2, to the critical bench width of separate failure Bs , are studied. The results show that the relative stability of the two level retaining structures of the multi-bench system changes with different soil strength. The parameter “Rfos” is introduced to reflect the influence of the soil strength, which is the ratio of the factor of safeties of the two level retaining structures when they are separated; Bs decreases with the increase of Rfos. A simplified analysis method is proposed to find Bs when Rfos is small; Bs will be constant when Rfos is large enough; Bs increases with the increase of L1; while it increases with the increase of L2 when Rfos is small, it decreases with the increase of L2 when Rfos is large.

In order to investigate the characteristics of extrusion displacement in the tunnel face and advanced core in tunnel with weak surrounding rock, the extrusion displacement of the soft fault area F215 in the left line of Qishan tunnel in Fujian province is measured with the GMD sliding micrometers produced by Solexperts AG Company. A series of numerical simulations are carried out with finite difference program to study the characteristics of extrusion displacement during the time tunnel passes through the weak rock zone; and the influence of the length of weak rock zone and the stiffness ratio of hard rock to weak rock are analyzed. The results show that: (1) The magnitude of extrusion displacement can reflect the quality of the surrounding rock of the advanced core, while the distribution of extrusion displacement in advanced core can reflect the condition of joint crack ahead of the tunnel face. (2) The range of disturbance in front of the tunnel face caused by excavation are around 1.5 times as long as the excavation span of the tunnel. (3) The extrusion displacement is able to increase or decrease in advance before the tunnel face approaches the area where the surrounding rock is changed. (4) When the tunnel face enters into weak rock zone from hard rock zone, the length of weak rock zone can affect the magnitude and the change trend of extrusion displacement in some extent. (5) The bigger the stiffness ratio of hard rock to weak rock, the faster the rate of extrusion displacement change increases; and the earlier the extrusion change occurs when the tunnel face approaches from hard rock zone to weak rock zone, while there is no difference when the tunnel face approaches from weak rock zone to hard rock zone. (6) The monitoring and analysis of extrusion displacement can be a supplementary method of advance geological forecast to distinguish the condition of surrounding rock ahead of the tunnel face.

Based on results of surface deformation and shaft cracks monitoring of Chengchao iron mine, the damage reasons of East main shaft are analyzed, by ways of numerical simulation; and then the feasibility of continuous use of shaft is discussed. By using post detailed monitoring data of ground and deep rock mass, a mechanical model for toppling failure is established. The relation between shaft’s crack growth and rock mass horizontal displacement and rock zone in East shaft area is discussed. The results show that: damage of the shaft is caused by underground mining. Horizontal displacement of rock mass has vital effact in shaft damage. The distribution of shaft cracks is related to goaf’s location; there are a lot of cracks on the East and West of east main shaft; but south and north are little. Numerical analysis results show that deformation of surface and deep rock mass will further increase along with the mining activities extend to depth; but deformation of deep rock still too small to lead to entire failure. Crack distribution in vertical direction is related to rock engineering zone by comparison.

In the Hoek-Brown criterion, many factors affecting rock failures are considered and the nonlinear failure characteristics can be described more accurately. It is known that the uncertainty of rock parameters seriously affects the application of the criterion. Using the sensitivity analysis and the displacement equation of surrounding rocks, the nonlinear regression method(NLRM) has been proposed for the analysis of the rock parameters of the Hoek-Brown criterion. In developing the above mentioned method, the uniform design and FLAC3D software are used. And we develop a reasonable back analysis method and procedures by leading into the differential evolution. The method is successfully used to analyze the stability of the tunnels in Qingdao metro. Results show that the NLRM can better reflect the relationship between the parameters geological strength index(GSI), agitating coefficient D, Poisson’s ratio and the displacements of tunnels. It can be concluded that the analytical results are very good agreement with the monitoring ones. The proposed method can be used for obtaining the parameters of the Hoek-Brown criterion accurately.

It is common to see the phenomenon of serious floor heave of gob-side entry retaining with large section in deep mine. To reveal the mechanism of floor heave of gob-side entry retaining with large section in deep mine; based on the engineering geological condition of 1115(1) working face tailentry and with the self-developed physical model test equipment, a study about the dynamic evolution law of floor fracture and floor fractal dimension in excavation period, the first mining influenced period, roadway retaining period, the second mining influenced period is conducted according to fractal geometry theory. And the relation between floor fractal dimension and floor heave is obtained. The results show that: First, the floor fracture developed, expanded and penetrated gradually with mining, and the fracture distributed mainly in middle and high angles because of shear failure. Second, the fractal dimension of floor fracture increased gradually, and there is a significant rise during main roof caving and roadway retaining. Third, as the spring back of main roof; the load from overlying strata of the second working face is small; the bottom fractal dimension increases slowly. Fourth, the relation between floor heave and fractal dimension is nonlinear and positive. By comparing the field measured and tested results of floor heave, it is found that the both two can be able to fit, so as to verify the model test results is reliable.

Because reservoir water is one of the master factor inducing slope landslide in the Three Gorges area, it is significant to study the stability of landslide under the condition of water level fluctuation of reservoirs. We make a study of the stability of Huangtupo riverside slumping mass #1 in Three Gorges area under the condition of water level fluctuation of reservoirs by the measure of geologic survey and in situ monitoring and theoretical analysis as well as numerical simulation. We make a study of the relationship between reservoir water level and the landslide groundwater level in the place mentioned above based on the analysis of field monitoring data. And we also analyze the deep displacement changed over time at different altitudes of the landslide as well as the influence of the variation of water level of reservoirs on the deformation of landslide via the same data. We make a simulation of landslide mentioned above through “3DDEC” and analyze the changeable rule of stress-strain of landslide under the variation of water level of reservoirs; and we put forward the strength reduction method considering the action of drying-wetting cycle and define the method to solve the safety factor. The results show that: it is reasonable adopting “3DDEC” to anlyze sliding slope; Huangtupo riverside slumping mass #1 is in a stable state under the action of current water transfer curve; in particular, we find that the low seismic intensity has little effect on the stability of the landslide based on the analysis of the deformation of the slumping mass before and after the Badong earthquake in December 16, 2013.

To overcome the deficiency of current risk pre-assessment method, the II class mining technical factors are defined and pointed out to reveal how the II class mining technical factors inherently induce the abnormal vibrations of coal and rock, and trigger disasters.The results show that: the greater the rate of face advance mining, coal and rock shake more frequent and the greater probability of the high-energy shock event, To decrease in low-level microseismic events, and high-energy event frequency increased, overall microseismic activity enhancement when the workface with a uneven advance rate, The method of blasting to relief stress in coal seam aimed the burst start-up areas of the roadway's sides, So the energy released of per kg dynamite during blasting much larger than the amount of energy released of blasting in roof or ground; the 7-18 h is the most effective period of dangerous lift. The original balance of stress field were broken by the repair in roadway's sides; the wall rock from a relatively stable state becomes unstable; the greater the rate of repair in roadway's sides, and the greater probability of the high-energy shock event. A sharp rise in the various levels of microseismic events, and the risk associated with high-energy events because of the ceasing and recovery production of workface.II class mining technology factors temporary intervention, breaking the original balance state, make coal rock macro adjustment, micro fracture suddenly disorder, stimulate coal rock impact events occur.

Since there exist some geological defects such as extensional fractures, weak layers and clay interactions in the right dam abutment of Wugachong Arch Dam, the dam abutment anti-sliding stability cannot meet the safety requirements, thus some reinforcement measures need to be taken. According to the Wugachong Arch Dam’s latest geologic data and the arch dam structure design results, a 3D numerical model for the whole arch dam is built. The joint elements for Mohr-Coulomb yield criterion are adopted to simulate the structure of the foundation’s extensional fractures, weak layers and clay interactions. Using the nonlinear finite element method, the deformation and yield region of foundation rock and structural surfaces before and after reinforcement are compared; the effectiveness of the reinforcement measures to the right bank abutment is evaluated. The deformation and yield condition’s development of arch dam and foundation rock is analyzed by using water density overload method. And the global safety of arch dam-foundation system after reinforcement is given. By comparison with similar engineering, the Wugachong Arch Dam’s global safety is evaluated comprehensively. The results show that the reinforcement measures to the extensional fracture L1can improve on the right bank abutment stability obviously. After reinforcement, Wugachong Arch Dam’s abutment has high overload safety which is superior among the high dams.

This paper studies the characteristics of Hefei remolded expansive clay. A series of three-dimensional swelling tests is conducted on cubic expansive soil of different initial moisture contents and dry densities. For the specimens investigated in this study, three-dimensional swelling pressures are unequal. The vertical swelling pressure is larger than lateral swelling pressure. The period of the rapid expansion is about 0-2 h; the vertical swelling pressure can reach more than 80% of the limit swelling pressure. Secondly, under the same dry density, the vertical swelling pressure decreases with the rise of initial moisture content; and there is a good linear relationship between these two elements. Meanwhile, with the increase of dry density, the rate of change between them also rises correspondingly. Furthermore, the graph of the relationship between the vertical swelling pressure and dry density illustrates that each curve presents bilinear relation based on the segmentation point which is dry density of 1.6 g/cm3. At last, from the graph of the relationship between the logarithm of swelling pressure and initial dry density, it can be seen that the relationship of ln(Pz)-ρd under different initial moisture contents displays a series of approximately paralleled and incremental straight line. And the similar slopes, of these lines demonstrate that the rate of change between swelling pressure and the initial dry density dose not change with the variation of moisture content.

With the rapid development of urban construction, the excavations of high-rise buildings and metro stations are becoming increasingly deeper. Consequently, the excavation will lead to a very large basal heave deformation and a very large center post upheaval, which will cause the redistribution of the internal forces in the supporting structures, and simultaneously influence the surrounding buildings and underground pipes. Through statistical analysis of the measured data of the center post upheaval in metro station excavations of Tianjin metro line 5 and line 6, the following conclusions can be derived. The maximum value of center post upheavals is approximately 1.2 times of the average value in an excavation. The average values of center post upheavals in excavations of two-level (15-18 m deep) and three-level (24-26 m deep) metro stations range from 5 to 40 mm and 30 to 55 mm, respectively. The ratios of center post upheavals to depth of excavations are less than 0.25%. The center post upheaval decreases as the embedded ratio of the diaphragm wall increase, and increases as the deformation of the diaphragm wall becomes larger. Therefore, controlling the deformation of the retaining structure would be an effective way to reduce the center post upheaval. The average value of center post upheavals in the excavations using the top-down construction method is much smaller than that using the bottom-up construction method, which ranges from 3 mm to 10 mm, equaling to 1/10-1/3 of that using the bottom-up construction method. Through fuzzy statistics, the normal center post upheaval in metro station excavations with depth of 15 to 18 m ranges from 15 mm to 25 mm.

Subsea tunnel of Dalian metro line 5 is the first large-diameter shield subsea tunnel in karst area in China. The tunnel across the sea is about 2.3 km and in form of a single-tube with double-line, using double-lining with a diameter of 11.8 m. The area which the tunnel through has complex geotechnical and hydrogeological conditions, locally karst development and rich groundwater, and many controlling factors; the design has encountered many difficulties. In this research, the sabsea tunnels which have single-tube with double-line have been compared with those have single-tube with single-line. The selection of large-diameter shield has been carried out under the condition of rock fragmentation and rich groundwater. Through the comparison of numerical simulation, the advantages of shield tunnel with double-lining under complicated geological conditions has been analyzed; and the optimizing design for the waterproof and drainage scheme is carried out combined with the lining form. Complete treatment measures are put forward on shield through the karst development area. The analysis results show that the subsea tunnel in karst area which has the exhaust air duct in form of a single-tube with double-lining is a better solution; and using the double-lining can significantly improve the durability of lining. The research results can be used as reference for similar underwater tunnel.

In order to investigate the influence of impurities on the mechanical behavior and the permeability characteristics of salt rock, different impurity contents of salt rocks are tested by the triaxial compression and penetration test .Researches show that the increased levels of impurities of salt rock will make the peak stress increase and the peak strain decrease. The stress-strain curve contracts to the zero ordinate. The changes of impurity content and confining pressure will have an impact on the salt rock permeability. When the impurity content is less than or equal to 50%, the confining pressure will have a bigger influence on salt rock permeability than the impurity content; but when the impurity content is greater than 50%, the impurity content will have a bigger influence on salt rock permeability than the confining pressure. Increasing confining pressure will forward the range of the influence on the permeability of impurity content. The increased confining pressure makes the difference between the permeability of peak stress and stress at zero point.

A fractured rock model is established with discrete fracture network(DFN); and then the relationship between fracture frequency and the Hoek-Brown parameters is deduced. By using the particle flow code, the anisotropy of rock mass strength before and after grouting is calculated; and the stress-strain curve is acquired along different directions and with different cohesive forces. With analyzing the physical meaning of the Hoek-Brown parameters, rock mass strength curve after grouting is fitted; and the influencing rule of grouting effect is analyzed. Results show that, after grouting, the compressive strength is improved significantly and the anisotropic property is decreased. The mechanical property of the rock mass changed from ductile to brittle. When the confining force is low, the compressive strength calculated from the model is different from that of the Hoek-Brown criterion; and the difference decreases when confining force increase. Based on the quantitative relationship between JCond and the Hoek-Brown parameters, the influencing law of grouting reinforcement on rock mass strength is acquired. The parameters is influenced to a larger extent by grouting effect. Since the parameter mb represents the own strength property of rock mass, while s represents the broken degree, the performance of grouting effect and the physical meaning match with each other, which proves the rationality of this model.

An elastoplastic damage model is established based on Mohr-Coulomb(M-C) yield criterion considering the plastic deformation mechanism and stiffness degradation of rock material in the framework of elastoplastic damage theory. The internal variable- equivalent plastic strain is used to characterize the evolution of damage variable of rock material. The M-C yield criterion is a six-pyramid in stress space, stress update exist a "singularity" problem on the six corners and ridge of a pyramid in the process of the numerical implementation. Angular point smoothing method is used to deal with this problem; but it inevitable lead to approximate results. The implicit return mapping algorithm of elastoplastic damage constitutive equation is deduced on the basis of the M-C constitutive numerical integral algorithm in principal stress space. It includes three main computational steps of elastic trial, plasticity correction and damage correction. Three conditions of flow vector returns to the main plane, ridge and sharp point are discussed in the plastic correction steps respectively. To solve the "singularity" problem from the angle of principal stress space, the elastoplastic damage constitutive solver(RDM-C) is compiled using C++ language with object-oriented programming method. The uniaxial compression test, the foundation and cavity example are used to analyze and compare the results of calculation. The results show that the established elastoplastic damage constitutive model can well describe the main mechanics and deformation characteristics of quasi-brittle material, plastic zone and damage zone change trend; the program can carry out numerical analysis for geotechnical engineering problems, so as to give certain guidance to the site construction.

For tunnels built in silty sand, the tunnel leakage can carry the fine particles into tunnels and generate seepage erosion, which will result in the tunnel settlement and damage the tunnel serviceability. This paper presents the tunnel displacement, soil stress distribution and ground settlement due to seepage erosion by using the discrete element method(DEM) simulation. The results show that the tunnel displacement and ground settlement increase linearly with the particles loss ratio. Particle arch formed around the erosion seam will redistribute the soil pressure; and it can lead to further expansion of the erosion seam and accelerate the seepage erosion process. And the seepage erosion in the inverse of the tunnel is more risky to tunnel serviceability than that in the tunnel waist and crown.

The implicit anchor cable element is adopted to simulate prestressed anchor cable in underground caverns. The equivalent additional stiffness contribution of the anchor cable attached to the rock element is discussed. Aimed at the loading process of the prestressed anchor cable, the force mechanisms of anchorage section under pre-tension and rock deformation loads are analyzed respectively. Based on internal force superposition of the anchorage section under the two loads above, a force analysis method for the prestressed anchor cable considering shear slip on the anchoring interface is proposed. Combined with the 3D nonlinear FEM, the general solving steps of force for the prestressed anchor cable are given. Then, the algorithm for the anchor cable is applied to the multistage excavations of the left bank underground caverns of Wudongde hydropower station. The results show that the anchor cable support can reinforce the rock effectively and restrict the development of damage zone. The axial force and shear stress of the anchorage section both reach the maximum at the anchor end, and decay along the depth direction. The calculated anchoring forces correspond well with the measured values, so as to verify the rationality of the algorithm.

The focus of prevention and control of water inrush from floor is to study the evolution of the intact floor from aquifuge to water-conducting. The coal seam mining causes the floor rock to bear the cyclic loading of compression – tension –compression , and causes the elastic modulus change. In this paper, the damage variable is elastic modulus, using double scalar D-P elastoplastic damage constitutive model, we established numerical model according to the conditions of Chengzhuang Coal Mine , and analyzed the evolution law of water-conducting of mining floor. The main conclusions are as follows: (1) Floor damage depth increases with the increase of the roof hanging area, and leads to the fracture depth increases again in last calculation step. Under the influence of filling body, the growth rate of the floor compression damage depth at the position of the coal wall is rapidly decreasing (the first roof caving), and finally reaching stability (the periodic caving). (2) Compression and tensile damage zones exist in mining floor simultaneously. And these zones are connected mutually, which determines the location of the water channel. (3) The elastic modulus of the filling body has a great influence on the failure depth of the floor; and the low value will lead to the rapid increase of the failure depth. The results of water injection experiment are basically consistent with the results of numerical simulation.

Three-dimensional (3D) geological modeling is an interdisciplinary research as well as a research hotspot. In this paper, a 3D stratum automatic modeling method based on Voronoi diagram of borehole planar point set is proposed in solving the problems of low modeling efficiency, low automation degree and lack of identification of stratum pinch and interlayers in current modeling method. The method firstly analyzes and processes the borehole data and classifies them according to the attributes of the stratigraphic blocks. Then the stratigraphical boundary is identified based on the Voronoi diagram through the determination of plane connectivity and elevation connectivity. Finally, the stratigraphic blocks are divided into two types, ordinary stratum and interlayer stratum respectively, with geologic model built for different strata. The method has been applied to an underground project of Nanjing, showing that it’s suitable for the modeling of sedimentary strata and in a better position to identify the pinch and interlayer phenomena commonly seen in the strata distribution, realizing the rapid and automatic modeling without human intervention.

In addition to the error influence of soil constitutive model, the material parameters reasonable or not are also one of the key factors affecting the prediction accuracy in stress and deformation control numerical simulation of high core rockfill dam. The traditional parameter back analysis methods do not consider the influence of correlation between material parameters which exist problems of parameter values may not match with the actual material properties; complicated geological conditions and many back analysis parameters make high computational burden. Therefore, according to Duncan-Chang E-B model parameters, through statistical analysis of a large number of experimental data, the calculation results show that the shear strength parameters △φ and φ, tangent modulus coefficient Ke and bulk modulus coefficient Kb, tangent modulus index n and m are significantly related by regression equations; then the basic model parameters φ, Rf, Ke and n are determined for back analysis. The response surface equation of basic back analysis parameters and calculated displacement values is established; and then the parameters optimum solution is obtained by using improved genetic algorithm and the known parameter regression equations. The Duncan-Chang model parameters are calculated by the combination of Pubugou Gravel Soil Core Rockfill Dam. The results show that the calculating parameters are more in line with the real characteristics of materials if considering the parameters correlation; the number of back analysis parameters decreases by 7, which can effectively improve the calculation efficiency; this method can be used as a reference for similar projects and has significant engineering application value.

Combining with a three-dimensional numerical model for a TBM tunnel of Lanzhou water supply project, the tunnel excavation process is simulated with finite difference method and the Mohr-Coulomb failure criterion to estimate the support installation time. Based on the convergence-confinement method, the deformation tendency of the monitoring section can be analyzed during the tunnel advancing. It is shown that the regularity of longitudinal displacement is related to the surrounding rock quality. The modified formula of longitudinal deformation curve can be fitted by the change regularity. With the method of virtual supporting force, the tunnel excavation can be assumed as an instantaneous progress in unique step to analyze the regularity between the deformation of surrounding rock and the excavation load releasing ratio. And the advance distance could be correlated to the excavation load releasing ratio with the same displacement completion ratio. So the supporting installation location away from the tunnel advance face can be determined by the excavation load releasing ratio when the deformation increases abruptly. The results show that the related parameters in the modified formula are convenient to be determined and satisfied with the fitting features. And the recommended supporting installation locations meet well with the common sense.

To deal with the problem of long-term settlement of the operating expressway, the Guan Yun section of the operating Lianyungang-Yancheng expressway, of which the embankment is improved by the lateral radiation grouting technique, is selected for analysis. A numerical model based on ABAQUS software is established to investigate the reinforcement mechanism of the embankment using the lateral radiation grouting technique. The proposed numerical model is then validated by comparing the calculation results of the ground heave, surface settlement of the ground after grouting, soil lateral displacement and excess pore pressure with the measurement in the field test. Subsequently, parametric study is conducted based on the presented numerical model. The results show that lateral radiation grouting technique can efficiently control the settlement of operating expressway and 5 cm reduction of settlement is achieved in field test section. The increasing of the grouting ratio is the primary factor which leads to the larger ground heave as well as the larger compression modulus of soil; and ultimate settlement decreases linearly with increasing of grouting ratio. Higher soil strength leads to insignificant effect of reinforcement, whereas no significant influence of heave is observed. The effect of grouting is more significant with the time in advance to reinforcing the ground. Thus it can be helpful to the compensation of previous settlement and the control of following settlement. The simple lateral radiation grouting technique has an advantage on reducing operating expressway settlement without influencing the traffic operation.

In view of the second phase project of the Jinping underground laboratory(CJPL) during construction, in-situ monitoring for each of the deep underground laboratories is conducted by using the 3D laser scanner, in order to obtain point clouds and the information of tunnel contour deformation, rock mass structure, as well as the volume of the rock mass failure by post-processing. Practice has proved that the contours’ temporal change of deep rock tunnels after excavation can be measured after the post-processing of the CYCLONE software; the accuracy of measurement can satisfy engineering requirements. Characteristics of the broken surrounding rock proved that the measurement is consistent with the actual deformation; the orientation of discontinuity can also be measured accurately and efficiently by using the CYCLONE software and the algorithm based on the unit normal vector of the discontinuity; and the results are in good agreement with those obtained by traditional method; and the post-processing of CYCLONE, Geomagic Studio and 3DMAX provides a simple and efficient method to measure the volume, area and depth of the broken rock mass induced by rock burst or collapse; the result of measured depth and volume of rock burst notch is consistent with those obtained by other methods. The measurement based on the 3D laser scanning and data processing in deep rock tunnels has the advantages of simultaneously measuring full-field deformation with fast speed, safety, and high efficiency; it is therefore a quite effective method for conducting research of rock mass behavior in deep rock tunnels.

At present, all bearing plates used in plate loading test(PLT) are rigid, which leads to a certain error in deformation modulus of the foundation soil due to without considering the actual distribution of the compressive stress under the plates. In order to realize a uniform load under the plate, a flexible bearing plate has been invented through the installation of an air bag under the traditional rigid bearing plate and has been proved applicable for PLT. During the PLT using the flexible bearing plate, the internal deformation of the air bag can be measured with the help of the inductance meter and the self-made sensor; and the load value at all levels is controlled by the resultant P and the air pressure p simultaneously. The indoor comparative test results show that the tested using the rigid bearing plate is about 14.0% larger than ones by using flexible bearing plate. The finite element method simulation also shows that the tested using the rigid load bearing plate is at least 10% larger than ones using the flexible load bearing plate; and an accurate can be get using the flexible bearing plate. So it can be concluded that the testing method for the foundation soils deformation modulus using flexible bearing plate is feasible and advanced; and the cost and efficiency can be fully accepted.