It is hot and difficult point that research on thermo-hydro-mechanical (THM) coupling for fractured rock mass at present. Firstly, the research status of mechanism, models, numerical simulation methods and contents for multifield coupling of fractured rock mass are summarized. Meanwhile, the significant effect on THM coupling of fractures is analyzed. As a result, the critical problem considering the fracture network propagation and its simulation during the THM coupling is proposed. Furthermore, 3 critical points are pointed out: (1) building the THM coupling model which can consider the fracture network propagation; (2) selecting numerical simulation method of simulating fracture propagation; (3) proposing the simulation algorithm for THM coupling and the whole process of rock mass from deformation to collapse. Then, the numerical methods for simulating coupling and fracture propagation are classified and compared; therefore, the various numerical methods, including finite element method, element-free method, partition of unity method, discrete element method, rock fracture process analysis method and numerical manifold method, are discussed thoroughly and particularly, from the advantages and disadvantages. Following, the numerical manifold method (NMM) is recommended for solving the critical problem. Finally, some ways and difficulties of the work are discussed preliminarily.

This paper analyzes the whole brittle failure process of rock from energy point, which enumerates and classifies variety of energy forms in the process of rock failure. It presents that thermal energy and mechanical energy must be distinguished when energy method is used to analyze the failure process of rock, because they have different effects. The relationship among input mechanical energy increment , releasable strain energy increment and dissipated energy increment is discussed through a symbolic cyclic loading-unloading curve; in addition, their transformation laws in different stages throughout the whole process are presented. The coefficient of brittle stress-drop has some shortcomings; and a new coefficient of energy-drop is presented in detail. Finally, this paper calculates energy-drop coefficient through the stress-strain curves in a series of confining pressure conditions of marble and granite, and obtains the relationship between the energy-drop coefficient and confining pressure. In addition, the effects of damage variable and Poisson's ratio on energy-drop coefficient are discussed. The comparison between brittle stress-drop coefficient and energy-drop coefficient with the existing experimental data shows that our model is reasonable and can be applied to more wide confining pressure conditions.

Due to sedimentation, particles in natural soil arrange anisotropically. Anisotropy diversifies the internal friction angles between relative sliding planes at different directions in soil material. Thus in failure analysis of anisotropic soil, except for conventional stress distribution coming from outside of material, strength distribution inside the material should also be taken into account in addition. Taking cross-anisotropic soil for example, failure mechanism considering both stress distribution and strength distribution is demonstrated. In the discussion, for simplicity, a linear relationship between the tangent value of the internal frictional angle of some planes in the cross-anisotropic soil and the spatial direction of the plane is presumed. For a cross-anisotropic soil sample in loading, when the condition that the stress state in somewhere of the sample achieves the strength where occurs at the first time, the cross-anisotropic soil sample is announced to be failed. Furthermore, more interesting results can also be obtained by analogy among the failure condition of three different typical materials which are metals, isotropic soils and cross-anisotropic soils. Failure occurs at the maximum shear stress plane for the metals, while for isotropic soils, the failure occurs at the maximum shear-compression ratio plane. Moreover, for cross-anisotropic soils, the failure occurs at the maximum shear-compression-strength ratio plan.

The seismic active earth pressure calculations problem with pseudo-static method is translated into non-seismic active earth pressure calculations problem in this paper using the transform method with rotating calculation model of retaining wall. Depend on the non-seismic active earth pressure formulations with differential layer method, the analytical formulas of resultant force of seismic earth pressure, application position of resultant force and distribution of seismic earth pressure with differential layer method are obtained directly, and the analytical solution of critical rupture angle by graphic method. The influencing factors including horizontal and vertical seismic accelerations, batter angle of wall back，cohesion and external friction angle between filler and back of retaining wall, equispaced overloading can be considered. The formulas can be used for seismic active earth pressure calculations of cohesive soil or non-cohesive soil with common border condition. The rotating seismic angle method in this paper is that the seismic active earth pressure calculation model with pseudo-static method is firstly rotated into static active earth pressure calculation model, and the stress states of retaining wall and soil behind retaining wall are not changed, and then the seismic active earth pressures with pseudo-static method are solved by the calculation methods of static active earth pressures. The deducing process of seismic active earth pressure formulations with pseudo-static method is simplified and unified greatly by using the new method. The seismic active earth pressure theory with pseudo-static method is perfected much more.

General dynamic drainage consolidation laboratory test, as tamping impact energy is not enough, some basic mechanical responses of soft soil in the actual project are difficult to excite, and relative features of soil are difficult to find. Through the self-developed multi-directional high energy electromagnetic force impact test system which can provide high impact energy produced by electromagnetic force and therefore could simulate the tamping energy acted in practice engineering, static and dynamic drainage consolidation model test for muck, is carried out. The experimental study obtains the response characteristics of pore pressure of this ultra-soft soil as follows: the time that upper pore pressure increases sharply to the maximum, which is very short (only 6 ms) at impact instant, and after the peak it drops rapidly to a certain value; in the initial twice tamping, the curve of pore water pressure at middle deep position shows bimodal type, the time interval between the two peak increases with the increase of tamping times gradually, and finally disappeared; each tamping, instantaneous earth pressure in the middle position shows a sharp growth and rapid decrease, and growth magnitude with the increase of tamping times shows a trend of decrease, but earth pressure value after tamping several days later is still greater than the value before tamping each time; after each tamping dissipating, the final value of pore pressure is less than the initial pore pressure, which signifies that under the certain condition of drainage, such ultra-soft soil foundation can be, indeed, acted by dynamic loading; the action mechanism of residual stress produced by dynamic tamping for soil consolidation exists, and it plays a main role for settlement, but for certain static loading, corresponding mechanism is little; the disturbance effect of inserting drainage board could not be ignored, but the disturbance effect decreases with soft soil embedded depth.

In order to grasp the swelling characteristics of argillaceous rock from coal measure strata in Cenozoic era, a self-developed soft rock swelling experiment apparatus is used to analyze swelling anisotropy and cyclic swelling-shrinkage. The essential mechanisms of swelling anisotropy and cyclic swelling-shrinkage of argillaceous rock are discussed by using scanning electron microscope (SEM). Results show that the swelling of argillaceous rock decreases with an increase angle between the horizontal plane of device and bedding plane of specimen, and has obvious anisotropy. The anisotropy property of argillaceous rock swelling with water is caused by the preferred orientation of clay mineral particles arrangement, and it can be quantitative described by swelling anisotropy coefficient. With the increase of wetting-drying cycles, absolute swelling ratio increases and tends to be stable, but relative swelling and relative shrinkage ratios decrease and stabilize. Cyclic swelling-shrinkage of argillaceous rock is the outcome of combined effect, which is alter of arrangement of mineral particles and energy dissipation during the occurrence and development of micro-cracks.

Soil arching has a notable influence on the behavior of piled reinforced embankment for its mechanically complex nature. A series of 3D model tests are conducted to explore the influence of the pile-soil relative displacement, embankment height, pile-cap spacing and horizontal reinforcement tension strength on the stress concentration ratio as well as the embankment settlement. The test results show that: soil arching is closely related to the pile-soil relative displacement and there exists a critical pile-soil relative displacement of approximate 6 to 8 mm which makes the stress concentration ratio reaching its maximum value. The bigger the ratio of embankment height is to the pile-cap clear spacing, the bigger the stress concentration ratio and the smaller the differential settlement on the surface of the embankment are; a bigger ratio of the cap width to the pile-cap clear spacing will result in a bigger stress concentration ratio and a smaller differential settlement. The installation of horizontal reinforcement within the embankment will effectively increase the stress concentration ratio and decrease the surface settlement; a low embankment as well as high tension strength of the reinforcement will enhance the function of the horizontal reinforcement. The equal settlement plane height is about 3.5 times the pile-cap clear spacing for 3D soil arch in piled reinforced embankments.

Sand soil mixed with waste tire shreds can be used as filling of subgrade, retaining wall or shock isolation system of base etc., which has many advantages, such as small earth pressure, good absorption of vibration, excellent durability and low cost. There are comparison between the mixture and the sand soil through digital dynamic triaxial tests, which mainly include the influence of the tire shred content and the confining pressure on the dynamic strength, dynamic elastic modulus and equivalent damping ratio. The results show that when the confining pressure and the dynamic shear stress ratio are equal, the dynamic strength of the mixture is slightly lower than that of the sand soil which is reduced by 20 kPa, 8%. The dynamic elastic modulus of the mixture obviously decreases with 22 MPa, 60% of the maximum reduction. The equivalent damping ratio of the mixture firstly increases, then decreases with the increasing of the tire shred content; the critical tire shred content is about 30%-40%. The mixture’s maximum increment of equivalent damping ratio is about 91%. Test results confirm that the shearing rigidity of the mixture can effectively reduce, which can exploit the advantage of the absorption of vibration to the full.

A constitutive model for unsaturated soils? coupling of the mechanical behavior and hydraulic hysteresis is proposed. The degree of saturation is introduced into the hardening equation to reflect the hydraulic effect. Meanwhile, the plastic strain is introduced into the soil water characteristic curve to reflect the mechanical effect. Therefore, the model could well reproduce the influence of hydraulic behavior on the stress-strain behavior and vice visa. An implicit integration algorithm for integration of the nonlinear constitutive model is introduced. Consistent tangent matrix that describes the relationship between stress and strain and the one that describes the relationship between stress and suction are both derived. A corresponding program code is developed, which can be then embedded into existing finite element code for numerical simulation. In order to verify the correctness of the code, it is used to simulate existing test data under different loading paths including drying-wetting cycle test and triaxial shear test. Results indicate that the model accurately predicts the coupling effect of mechanical and hydraulic behaviors of unsaturated soils.

Simulated rock joint samples with second-order asperity are made of artificial material. A series of constant normal load (CNL) cyclic shear tests are carried out to study the deterioration law of shear mechanical characteristics during process of cyclic shearing. Based on the experimental results，it can be found that the second-order asperity has an important influence on the shear mechanical properties of joint samples under cyclic shear loading. The shear strength, shear stiffness and dilatancy angle decrease with an increase of shear cycles, and decay more quickly with an increase of second-order asperity height. The influence of second-order asperity on the shear mechanical properties is mainly reflected in the first shear cycle with higher height of second-order asperity under higher level of normal stress, and it has no obvious effect on subsequent shear cycles. On the other hand, the influence is reflected more clearly during the begging of the shear cycles to the joints with smaller height of second-order asperity under lower level of normal stress. Finally, based on the theory of Hertz contact mechanics, a spherical contact microscopic model of asperity on the joint surface is proposed; and the mechanisms of macroscopic phenomenon during cyclic shear tests are revealed by the model.

Dynamic centrifuge tests are carried out to study seismic response of caisson-pile composite foundation. With Shanghai sandy silt chosen as test soil, laminar shearing box used to eliminate reflection at the boundary, and Shanghai artificial middle wave is taken as the input motion, three tests with different foundation types are conducted under the centrifuge acceleration of 50g. Single pile, caisson and caisson-pile composite foundation are the foundation types for those three tests, and all the superstructures in these tests are simplified as mass points and connecting columns. Test results indicate that, for soil with low stiffness acceleration decays in the process of earthquake wave propagating upwards; adding piles under the caisson could decrease the earthquake responses of both the foundation and structure, so the reinforcement of the system in resisting earthquakes is expected; frequency characteristics of the responses at soil surface, foundation and structure are all different from each other depending on their own natural vibration characteristics; and for the interaction between soil and foundation, or foundation and structure, only the earthquake component with similar frequency with both interacting sides can cause remarkable earthquake interaction.

To investigate the effects of shear ring, drilling mud skin and anticorrosion coating on performances of steel tubular composite (STC) piles, five model tests with different combinations of shear ring, drilling mud skin and anticorrosion coating are conducted; two of them are with shear ring, relying on the construction of the Hong Kong-Zhuhai-Macao Bridge. The load-deformation curves and deformations of cross-section, steel tube and shear ring have been compared and analyzed. The results obtained from the tests show that the bond strength of STC pile is reduced by drilling mud skin and anticorrosion coating, while the performances of steel tube are improved by shear ring. The cross-section deformation of pile shows "inverted v" or "m" type; it no longer meets section deformation assumption of classical mechanics. The disadvantage effects of drilling mud skin and anticorrosion coating can be completely overcome by the shear ring, when its spacing is less than 2D (D is pile’s diameter). Based on the test results, the stiffness calculation of STC pile has been discussed and the stiffness calculation formula in elastic stage has been given. The stiffness of STC pile is reduced by drilling mud skin with thickness of 0.1 mm and anticorrosion coating, which is improved by shear ring. The paper will provide references for STC pile’s design.

In order to improve test method of soil-water characteristic curve (SWCC), the pressure plate extractor is employed and drying tests are carried out on the basis of four cutting ring specimens and twelve triaxial specimens. The potential factors and abnormal phenomenon in the test are investigated. The results show that there are differences between the SWCC of specimens, even if the specimens are reconstituted at the same condition, and the differences have a direct relationship with the poor particle size distribution. There is the evaporation effect in the drying tests, and the water loss caused by evaporation is dominant with the increasing of time, so equilibrium condition should be adjusted on the basis of evaporation. The SWCC is obviously influenced by side protecting, especially to the specimen with big ratio of height to diameter, evaporation will become main factor of water loss without side protecting. The transverse crack which is an abnormal phenomenon in the specimen does not affect the result of SWCC, but it should be further investigated because the generation mechanism could show the shortage of axis translation technology. Based on the above conclusion and other test results, some suggestions and improving methods for SWCC test are proposed.

When backfilled to abandoned salt caverns full of brine, alkali waste particles will settle freely and form a sediment layer at the bottom of salt caverns. This layer may consolidate further under its own weight. In order to understand the sedimentation and consolidation behaviors of alkali waste backfill in salt caverns, settling column tests together with oedometer tests are conducted on alkali waste from Huai'an in Jiangsu province. Test results show that: (1) The settling process of alkali waste in brine can be divided into three stages: flocculation stage, settling stage and consolidation stage. The settling curve and settling rate are significantly affected by the initial concentration. (2) The particle size distributions, density, water content and void ratio of alkali waste all show layered characteristics. The particle size and density increase with depth, the water content and void ratio decrease with depth. (3) The alkali waste has a very high compressibility; and the value of a1-2 is 3.36 MPa-1. The consolidation coefficient of alkali waste decreases significantly with an increase of consolidation pressure in stress range of less than 100 kPa. The test results are important for the study of sedimentation and consolidation behaviors of alkali waste backfill in salt caverns, and they can used to guide the backfill construction technology and reinforcement processing of alkali waste.

With rock sample of coal seam roof as matrix and steel wire as bolt, anchored rocks have been experimented by means of uniaxial compression, Brazilian split and pressure-shear test. The results show that: when rock matrix comes up against plastic yielding and certain cracks begin to extend, anchor bolt gradually becomes the main carrier of external load and rock's failure characteristics also change from fragility to ductility. During the process of splitting disk samples, a certain crack in the center of part of samples have no obvious impacts on carrying capacity; its strength increases by 51.1%. A huge penetrating crack turns up in other parts of samples and it quickly loses the carrying capacity; its strength increases by 91.6%. Failure forms of uniaxial compression samples can be divided into two categories. The first is failed with cracks propagating parallel with bolt; and the second is failed with cracks propagating vertically with bolt; the strength of anchored rock increases by 34.6%. In the pressure shear test, the carrying capacity of anchored samples obviously deteriorates once again; and the result shows that its internal friction angle of anchored samples isn't changed while the cohesive force rises by 22.9%.

In slurry shield construction, forming a filter cake in time is important for working face stability; the slurry pressure could be transferred into effective stress with filter cake then acting on the working face. The filter cake on the working face is dynamic, thus the forming time of filter cake is the main factor which could affect the supporting for working face. An apparatus is designed which could measure the excess pore pressure in the stratum. Infiltration tests are done in three kinds of high permeability strata with five kinds of slurry to study the forming time of filter cake, its supporting ability and the influencing factors. The results indicate that the forming time of filter cake is 10 seconds in only filter cake infiltration styles. The slurry property and the grain size of stratum have important effects on the forming time of filter cake. The filter cake forming time in part of large slurry shields at home and abroad is also discussed; and the results indicate that the time from destruction to re-destruction of filter cake is ranged from 5 seconds to 20 seconds; thus the property of slurry should be suitable to ensure that the forming time of filter is less than the time from destruction to re-destruction of filter cake.

Strength and deformation characteristics of rock salt are extremely important parameters for the design, construction and safe operation of underground energy and waste repositories. However, these require accurate measurements of the strength parameters for the concerned rock salt. In this study, samples of rock salt from Jintan in Jiangsu province and Jianghan in Hubei province, respectively, are chosen for triaxial compression tests to locally determine their short-term strength and deformation parameters. This allows a comparison of the Germany test and data processing methods, performed on behalf of the Western countries, and the Chinese test and data processing methods. Based on the German method including its shortcomings for determining the damage boundary of Jintan rock salt which was employed in the German short-term strength test, this paper presents an improved method and calculates the damage boundary for the Jintan rock salt. Comparison between the two test and data processing methods reveals that German experimental measurements yield lower strength parameter values for rock salt with large deformation. Hence the German test and data processing methods, in which the change of the sample cross-section area is considered and the data are secondarily revised by using scientific strain instead of engineering strain.

Dispersive clay is a kind of soil with special engineering properties, and with typical features of poor impermeability, low erosion resistance ability, very high dispersiveness when it is in pure water. In recent years, the study of dispersive clay in the field mainly focuses on identification, penetrability, betterment and other aspects; however, the studies of shear strength properties are rare. In this paper, the conventional triaxial compression consolidated undrained (CU) test is adopted to study the dispersive clay’s shear strength characteristics under different initial conditions. The results show that: dispersive clay’s stress-strain curves present the softening type when it is under the conditions of small confining pressure, low moisture content and high dry density; but it changes into the weak hardening type or hardening type when it is under the conditions of large confining pressure and high moisture content. Dispersive clay’s cohesion and internal frictional angle all decrease while the moisture content increases. In addition, the higher the dry density is, the stronger influence of moisture has on the clay’s cohesion and internal frictional angle; its cohesion increases with the increase of dry density; and it has a larger increment under the low moisture content condition compared to that under the high moisture content conditions; internal frictional angle has a small increment with the increasing of dry density.

As a fractal model, percolation method can analyze salt rock failure process and damage evolution under triaxial compression by creating a percolation model to locate the salt rock failure grid by using acoustic emission (AE). Percolation model shows that the slope of relationship curves between cluster number and the largest cluster occupancy for each specimen percolation model is basically equal after 70% of peak stress. The extension of the largest cluster along the specimen axially agrees with the evolution of cracks; and the critical failure probability is determined by the end of the largest cluster in axial direction, which is very important for the study of the sharply increased permeability point. The starting point of damage is determined by the correlation length of percolation, the average distance between two points in the same clusters, and the damage factor is calculated by percolation model failure probability which is accordance with the damage factor calculated according to AE parameters such as AE count numbers or AE energy . The research results show that percolation is a promising method to describe rock failure process and damage status so as to provide a novel approach for studying the rock failure and its cracks propagation.

Based on present studies of the enhancement of root system on soil shear strength, this study investigated root reinforcement effect of six common plants, i.e. Pinusmassoniana Lamb, Cinnamomumcamphora (L.), Linderakwangtungensis (Liou) Allen, Gordoniaacuminata Presland Neolitseaaurata var. glauca, within acidic zheltozem area of Chongqing Jinyun mountain, by direct shear test and numerical modeling. This study was firstly implemented by a self-made large box direct shear apparatus, characterized by simple, economic, effective and reliable. Moreover, the root system reinforcement effect was quantified by the equipment. Besides, the root area ratio was calculated and root tensile strength was derived by laboratory test experiment. Further, the well-known Wu root-soil composite model was triggered with the same boundary condition as indoor experiment; and then the model calculations were compared with the experimental measurements. The results show that the above six types of plant roots notably enhance the soil shear strength, but with different levels. It is also demonstrated that Wu root-soil composite model overestimated soil shear strength by 90% compared with the large box shear test. In this manner, we revised the k value as 0.63 for soil textures in Jinyun mountain of Chongqing.

Salt migration and enrichment caused by the capillary migration of the salt solutions have been the important cause of mural deterioration. The soluble salt redistribution which influenced by the capillary migration of salt solutions in mural plaster under different humidities is studied. At the same time, the increase in height of capillary with time, water content and electrical conductivity distribution with height, specimen surface before and after capillary saturation under different environmental humidities, either the content of the soluble solution distributions with height after capillary migration are analyzed. The test results show that, the lower the air relative humidity is, the more water migration to air during the capillary rise is; it is difficult for water to move upward at the same time. The water content of samples with height decreases, but the electrical conductivity of samples with height increases. The crystallization of soluble salt in rising capillary water occurred. NaCl crystallization is enriched in capillary striker, Na2SO4 crystallization is enriched mainly in the second striker. The results of this study can provide a scientific basis for preventing and controlling salt damage of the mural.

Focused on the failure modes of prestressed anchor cables, according to Hoek-Brown failure criterion and associated flow rule, the ultimate pullout force and failure mechanism of anchor cable were deduced through upper bound limit analysis, where bond failure of anchorage body and anchored rock mass failure were considered respectively. The influences of grouting pressures, lengths of anchorage section and rock parameters on ultimate pullout forces and failure mechanisms were analyzed. The results reveal that, increasing anchorage length in a certain extent and using pressure grouting are effective measures to improve ultimate pullout forces of anchor cables. When anchored rock mass failure occurs, ultimate pullout forces will increase with the improving of empirical parameter A, tensile strength, compressive strength and unit weight of rock mass, while it will decrease with the improving of empirical parameter B. The shape of failure surface of anchored rock mass looks like horn, which is consistent with the conclusions of existing literatures; and parameter B is a key factor affecting the shape of failure surface of rock mass; it determines the curvature of failure curved surface; and curved surface will degenerate into circular conical surface when B is equal to 1.

The conventional method of determining rock mechanical parameters now can only obtain the overall strength of the rock; while in the weathered layer of ancient buildings rock constructional elements, of which the mechanical parameters gradually change. It is not enough to study the stability and durability of rock ancient buildings. So a method with integrated use of on-site sonic CT test, surface rebound and laboratory test to obtain the mechanical parameters of rock constructional elements is proposed. The method is put into action as follows. The longitudinal wave velocity distributions along the depth profile in the rock constructional elements are acquired by the on-site sonic CT test. The statistical relation of the mechanical parameters and wave velocity is obtained by selecting rock on-site that analogous to the rock constructional element studied to do the indoor mechanical tests and the wave velocity test. The mechanical parameters distribution along the depth profile in the rock constructional elements is derived by combining the outcomes mentioned above; based on this, the relationship between mechanical parameters and depth within the weathered layer is analyzed. The relationship between the surface compressive strength ratio and the weathered depth is derived by weathered depth studying and surface rebound test on the typical rock constructional element in different weathering zones. This method is systematically introduced in this paper with the example of Guyue Bridge in Yiwu built in the Song Dynasty. This paper studied the relationship between mechanical parameters and depth within the weathered layer and the relationship between surface strength of rock constructional element and weathered depth of weathered rock constructional element which were in the bearing structure of the Song Dynasty Guyue Bridge in Yiwu. The studies show that: in the bearing block stone of the Song Dynasty Guyue Bridge, the compressive strength ratio and the elastic modulus ratio vary negative-exponentially with the depth in weathered layer; the relationship between compressive strength ratio of surface and weathered depth conforms to the two order polynomial.

Based on the field tests of vacuum well-point dewatering, the evolutions of groundwater level and the variations of the water flow in silt ground layer are studied under combined gravitational and vacuum negative pressure, which include both the cases of a single well-point and a single row well-point. Test results show that, for the condition of a single well, the declining depths of groundwater level increase with the increase of vacuum negative pressure and the depth of drainage well, and the declines of groundwater level at the points away from the drainage well will be more obvious. For the condition of a single row well-point, with the increase of the depth and space of drainage wells, the declines of groundwater level are also very apparent whether along the direction of well-point arrange or in the perpendicular direction of well-point arrange; and the former is more obvious. On the other hand, the declining ratio of groundwater level has an increasing trend after several repeated dewatering processes. Besides, the vacuum pressure in the mouth of a well is lower than it in the water outlet of vacuum pump with a loss of approximately 12.5%, which indicates that the length of the pipeline of water outlet should be considered in the design of vacuum well-point dewatering in practice.

Aiming at the problem of open excavation adjoining bridge piles of Xianggong station construction of Dalian subway line No. 2, the paper constructed the remote automatic monitoring system, arranged the sensors of static force level, electronic yaw equipments and electronic axial force meter, etc. to monitor the information of construction process. Based on Visual C#. Net platform, an intelligent analysis system is developed combining support vector machine and differential evolution algorithm, three- dimensional mechanical parameters back analysis method and time series forecast method are constructed, the software includes four modules of data operation, feedback analysis, data forecast and visualization display. The method and system are applied to the open excavation of Xianggong station. The multiunit messages are collected, then based on the monitoring data, the elastic parameters of the second layer and the third layer are identified by differential evolutionary algorithm; the maximal relative error between the results of feedback calculation and monitoring data is 8.23%. The supporting schemes in the excavation process are simplified accordingly. Furthermore, the sedimentation of bridge pier QCJ-13-01 is forecasted and alarmed by DE-SVM nonlinear time series model; and the measurement of micro tubular insulating piles is adopted at once, which can control the bridge pier settlement effectively. The method combines advanced hardware technology and software analysis function, providing effect approach for complex underground engineering.

Jointed rockmass is involved in many civil engineerings. Correct assessment of the shear strength of rock joint surfaces is essential for such projects design. However, there are various factors to affect shear strength of rock joints. Among them, the surface shape of the structure plane is vitally important for its mechanical property because the surface shape affects the real area of contact and frictional status definitively. In this study, the rough joint surface is considered to be made up of a series of microcosmic rectangular-shaped asperities with different heights. There might be two failure modes of a rectangular asperity: a dilative failure mode and a non-dilative failure mode, although the rough joint surfaces show macroscopic shear-dilatancy failure in most cases. Based on them, the stochastic strength model of rough joint surfaces is established by applying the probability density function to describe the asperity height distribution. The shear strength is theoretically derived according to the proposed model. Direct shear tests on artificial rough joint surfaces are performed to verify the proposed stochastic model and its application method. The theoretical computations of stochastic model provide a good agreement with the obtained peak shear strength and residual shear strength from shear tests, which may serve as an effective approach for quantitatively estimating the peak shear strength and residual shear strength of rock joint surfaces.

Artificially frozen wall is a temporary support structure in tunnel freezing engineering; and frozen wall will gradually thaw after construction of the tunnel lining. In the process of frozen wall thawing, thawing settlement of ground can produce serious influence on the surrounding environment. So a reasonable method must be established for predicting surface thawing settlement. On this basis, suitable thawing settlement prevention measures can be determined in the actual construction. For this reason, considering the thawing process of frozen wall, using stochastic medium theory, a duration prediction model of surface thawing settlement in the period of tunnel construction with horizontal freezing method is presented. Temperature field under natural thawing conditions can be approximately analyzed by flat-panel thawing theory; based on flat-panel thawing theory and thawing settlement content calculation formula in one-dimensional case, value methods of thaw front radius and thaw compression region inner radius are determined in the duration prediction model. The prediction method is applied to circular tunnel full section horizontal freezing engineering, surface thawing settlement variations with thawing time are presented. The results show that surface thawing settlement grows faster in the early stages of thawing, and grows slower in the later stages of thawing. Surface thawing settlement variations with thawing time is presented, which is consistent with thawing settlement characteristics of natural permafrost researched through test method by ЦЫТОВНИЧ.

During tunnelling works with the method of drill and blast, millisecond delay blasting technique is always employed to reduce charge weight in a single fire for safety. Under the repeated blasting loads, cracks are propagated in quantity and extent, or connected gradually to main cracks or collective cracks, leading to irreversible accumulation of damage in remaining rock masses. However, considerable numerical calculations are directed towards a single-hole charge and a single blasting, and they rarely get involved in the repeated blasting. In the present study, the millisecond delay blasting in a circular tunnel is simulated to find out the effect of repeated blasting on the rock mass damage, where in-situ stress in surrounding rock masses is also considered. The numerical simulation is implemented by embedding a statistical damage model into the commercial software LS-DYNA through its user-subroutines. According to the simulation results, rock masses subjected to the repeated blasting loads in a blasting footage result in relatively excessive damage than a single blasting. The peak particle velocity (PPV) threshold for initiation of damage is reduced by 12% due to repeated dynamic loading. The blasting load mainly induces tensile damage to surrounding rock masses. However, this tensile effect is very easily inhibited by the in-situ stress in surrounding rocks. When the in-situ stress reaches a magnitude of 2 to 10 MPa, the accumulated damage extent is significantly reduced with the increasing of the stress, and the PPV threshold for initiation of damage increases by 24% to 57%.

Monitoring data show that the soil landslide or the rock landslide with the aging deformation characteristics, often have creep characteristics; namely it generally undergoes three stages from the beginning to the failure: the initial deformation, the constant speed deformation and the accelerated deformation. Based on the characteristics of typical accumulation displacement-time curve of the landslide, a method has been proposed to determine the different deformation stages of each point of the landslide mass. Taking the displacement speed ratio (DSR) as a general indicator, when DSR 0-2 means the constant speed deformation, and greater than 2 means the accelerated deformation. Based on some typical landslide cases, a displacement over-acceleration criterion has been established to determine the different deformation stages of each point of the sliding mass: DSR=2-6 means the initial acceleration stage; DSR=6-8 means the intermediate acceleration stage; DSR greater than 8 means the pre-slippery stage. A geographic information system (GIS) based method of DSR has been proposed for the spatial stability evaluation of landslides. As an example, the method has been used to determine the spatial deformation state of Jinpingzi landslide; the result verifies its feasibility and reasonability.

This paper studies the relationship between wave velocity and rock brittle failure during the whole process of compression. The complete testing data for the stress-strain curve and the associated wave velocity-stress curve are obtained. The variation caused by internal cracking of the rock causes the corresponding variation of rock wave velocity, especially when the stress level reaches to 70%-80%. Based on the experimental results, it is shown that the stress at the critical point on the stress-strain curve is corresponded to that at the rapid deduced point on the wave velocity-stress curve, where the microcracks are rapidly growing. With the reducing of wave velocity, the travel times and discrete degree of S-wave and P-wave are sharply increasing. The amplitudes of S-wave and P-wave are reducing. However, the amplitude ratio between S-wave and P-wave is increasing. The Q values of S-wave and P-wave have a mutation phenomenon nearby the yield point of stress-strain curve. Considering the relation between wave velocity variation and stress-strain curve, this study shows that wave velocity and its characteristic parameters could be used as the sensitive parameter in the failure process. From this research, we can use the comprehensive information source to indentify the critical point of rock brittle fracture.

Two hundred and one groups of cone penetration test (CPT) data from 19 projects in Shanghai are adopted. The distribution of clay, silty clay and silt in Shanghai area are obtained. The specific penetration resistance (Ps), cohesive strength (cu) and frictional angle (?u) of consolidated quick shear test, void ratio (e), and plasticity index (Ip) are varied along the soil depth. The soil shear strength (Su) of clay, silty clay and silt are correlated with specific penetration resistance (Ps) of CPT. The correlations between Su and Ps are summarized for various types of soft soils in China. It has been found that the correlation coefficients of clays obtained from this study are similar to the published data. Also the in situ soil correlations of silty clay and silt are given. These correlations of Su with Ps are useful for classified soil and valuable to engineering application. According to correlations in this paper, the calibrated correlation coefficients can be used to determine Su based on Ps for foundation pit stability calculation. The results of the study can be used for geological investigation and engineering design work.

Combining theoretical analysis, practice and actual measurement, a retaining roadway for the next sublevel technological theory of end zone below steep inclined coal seam and systematical technology were discussed; the influencing factors of the forces posed on the filling object were obtained, and a filling technique that applies to steep inclined coal seam was brought forward. The research shows that loading capacity of roadside packing adjacent to steep inclined coal seam is affected mainly by the effective length of the gob gangue, inclination angle of coal seam, designed width of filled architecture, and the thickness of coal seam, whereas it is less affected by installed anchor of roof and floor. The deformation rule of bearing gangue reveals stage characteristics under the uniaxial compress, and the stress retain a nearly linear relationship with strain during every stage. The bearing capacity and deformation of backfilling matter are notably dependent on working distance, displaying different characterizations as follows: the closer the backfilling matter is to the work face, the smaller the deformation rate of backfilling matter is. The field practice in Xinqiang coal of Qitaihe city demonstrates that, the concrete filling process system of gangue in sharply steep coal seam can be expediently carried out and conveniently operated, and the overall effect of gob is obvious.

A nonlinear peak shear strength criterion, proposed by Maksimovic, uses a simple hyperbolic function to describe the peak dilatancy angle under different normal stresses. The model has significant advantages, such as parameters have physical meaning, law is valid from zero to infinity, and it is simpler from the view of mathematical point. The roughness of joint surface is expressed by the parameter of “roughness angle, ”, obtained by using the least square fit method on basis of at least three sets of measured data. It is not easy to use the Maksimovic criterion to predict the peak shear strength of rock joints. In this paper, the roughness angle is determined by a rational method with a quantitative three dimensional morphology parameters of joint surface. Then, a modified Maksimovic peak shear strength criterion is proposed. Several experimental results are used for verification of the proposed relations. It is shown that the calculated values are in good agreement with the measured data. It also presents the comparison between the new criterion with the famous Barton’s criterion. We can use the proposed criterion as a useful tool to predict the peak shear strength for rock joints.

With the theory of fluid mechanics and fracturing mechanics combined with Monte Carlo method to describe random distribution of rock cracks, seepage-fracture coupling mechanism involving deformation of primary crack, initiation, propagation and coalescence of wing cracks under high hydraulic pressure was studied. The mathematical model of seepage-fracture coupling of rock masses cracks propagation was established. The solving strategies and methods were proposed, as well as developing the analysis program HWFSC.for for seepage-fracture coupling of cracks propagation under high hydraulic pressure on the Fortran95 platform. The fact that crack networks and seepage initial condition vary with seepage conditions embodies in seepage-fracture coupling of cracking propagation under high hydraulic pressure. Coupling analysis of the process of rock cracking propagation during high pressure water injection process comes to the conclusion: starting water pressure has been shown to reside in rock cracking propagation under high hydraulic pressure, when the water pressure is more than the starting water pressure, the wing crack is born on the crack tips, as water pressure on the crack tips increases, the wing cracks propagate, and then coalesce with other cracks, finally stop propagating . The analysis of seepage-fracture coupling considers the influence of the dynamic and static water pressure of the cracks on the cracks normal expansionary and the wing cracks propagation, and the number of connected cracks increases as the seepage develops. Analysis of seepage-fracture coupling analysis of rock cracks can re-create the phenomenon of hydraulic fracturing, describe the process of rock cracks propagation, the rock bridge coalescence and inter-coupling response of seepage in fractured rock masses.

According to the drawbacks that the evaluation results by different rock mass classification systems are not consistent and the rock mass mechanical parameters between indoor tests and current situation have a great gap, a method named rock mass fine description system is recommended to describe surrounding rock mass structures quantitatively. Firstly, these evaluation indexes of the common rock mass classification systems(RMR、Q、RMi、GSI、BQ、HC) are summarized as some groups, and basic indexes are selected from these groups by the in-detail comparative analysis. Then, some sections of powerhouse in Danggangshan hydropower station are chosen as the research objects; we use the method combining the in-situ rock mass fine geological sketches with post-data mining and fitting, and based on the association relationship between the ranking parameters and the basic ones, these probabilistical distribution models and their relevant parameters of evaluation indexes are able to be required; thus the surrounding rock mass elaborate descriptions of the section can be obtained. Based on the rock mass fine description, lots of random numbers that meeting the probabilistical distribution models and relevant parameters of these evaluation indexes can be produced by the Monte Carlo simulation; and then according to the evaluation idea and rating process of each rock mass classification system, plenty of corresponding random rating-values of these evaluation indexes are also gained; the surrounding rock mass evaluation results and these probabilistical distribution characteristics by six rock mass classification systems can be attained easily by the inductive statistics. At last, these probabilistical distribution characteristics and their relevant parameters of these rock mass mechanical parameters can be decided by the correlation formulas between them and the rock mass classification indexes. This research can provide some references to estimate accurately the rock mass classification and mechanical parameters in some similar projects, and offer the essential primary data for supporting limit state design to the surrounding rock mass.

The conventional design method of deep excavation retaining structure generally processes element by element, consequently, some retaining structures are probably lack of essential redundancy, which is one of the reasons that led to many catastrophic collapses of deep excavations. Discrete element method (DEM) is adopted for simulation of excavation collapse and study of retaining structure redundancy; and a simulation method based on local failure for analyzing redundancy is also proposed. Here the influence of prop connection on the retaining structure redundancy is selected as an example of redundancy research. The failure processes of two excavations with different types of prop connections are simulated; and the phenomena of progressive collapses in them are compared and analyzed. Furthermore, the simulation results are also validated by comparison with the realistic case of excavation collapse. It is indicated that the improvement of the retaining structure redundancy can effectively resist the progressive collapse in deep excavation, and then the transformation of a type of damage to other types of damages and the evolution of the local damage to entire collapse can be avoided. In addition, the simulation results also show that the excavation collapse using DEM is feasible and reasonable, so as to provide a reference for simulation of such collapse problems in underground engineering and further study of redundancy in deep excavations.

Numerical domain is discretized by triangle elements; and local coordinate system is set up for each one. X-axis of local coordinate system is along one edge of the element; and the origin point is at the endpoint of the edge. In local coordinate system, based on Green formula and Darcy law, analytical expression of pressure gradient and flow velocity of element, discharges of each edge and each node are given. The seepage “pipeline” network similar to solid spring system is formed; and the relationship between pressure difference and discharge of pipeline is built. Flow velocity and discharge of each element in element local coordinate system should be transformed to global coordinate system, and should be accumulated in each node. By introducing fluid bulk modulus and node saturation, pore pressure of each node could be calculated explicitly and the unsaturated problems could be simulated well. The method based on local coordinate system is clear in physical meaning and simple in solution process. According to constructing the relationship between pressure difference and discharge of pipeline in local coordinate system, the seepage stiffness matrix of FEM is simplified to two seepage stiffness values; so the memory is saved and the efficiency is improved. The results of 4 numerical cases almost coincide with analytical solutions so as to demonstrate the solution precision when simulating steady-state, non-steady-state, saturated, unsaturated seepage problems.

The self-boring in-situ shear pressuremeter (SBISP) has little disturbance to the surrounding soil. It can simultaneously determine the deformation and strength parameter of easily disturbed soil at depth and has an extensive application prospect in the determination of soil parameters accurately. However, the deformation response of surrounding soil under multilevel loading process in SBISP test has seldom been studied up to present because of the limitations of the analytical tools and research level. At the same time, the determination of the deformation parameter of the soil is closely related to its deformation mechanism. Based on this, the SBISP model test under different consolidation pressures is simulated by particle flow code in three dimensions (PFC3D). The results of numerical experiments show that the displacements of particles in central area increases with the shear stress imposed stepwise; and the direction of displacement vector shows a clearly preferred direction. The shape of displacement vectors in influence area is a reverse cone under the fifth grade shear stress. Additionally, with the increase of the consolidation pressure, the influence area of the numerical sample diminishes gradually. The motion trails of particles are step-like lines; the steps are becoming gentler as the distances from particle to the probe rob center increasing; and the vertical displacements of particles descend in a negative exponential form. The magnitude of shear stress depends on the frictional coefficient of the probe; the shear stress-shear displacement curve is no longer changes when it reaches a certain value. This study is of great enlightened significance in the further research of the relation between deformation process and deformation modulus of soil under multilevel loading process in the SBISP test, which lies in the influence area.

Soilbags have been understood to be cheap and easy to acquire as well as vibration reduction. However, the research on the effect of soilbag vibration reduction is only based on test results at present; the mechanism of it has rarely been studied. Based on the principle of soilbag energy dissipation, the discrete element method is used to build energy dissipation equation during the process of soilbag vibration reduction. Firstly, using the discrete element method to establish every part of soilbag energy dissipation equations, through numerical simulation of a single soilbag under simple vertical loading condition, from energy conservation perspective to verify that the calculation of each part of the energy is reasonable; meanwhile, the correctness of the established equations of energy dissipation is proved; and then energy dissipation of a single soilbag is simulated from quantitative perspective by using the verified energy dissipation equation under the cyclic loading rate of 1 000 N/s three times. The numerical simulation results show that the percentage of total soilbag and its inside particles energy consumption exhibit obvious wavy shaped fluctuating with loading and unloading; the percentage of it is over 75% of the total energy; this means soilbag can play a good effect on energy dissipation.