Drying characteristic curves for two compacted clayey sands with different dry densities and initial moisture contents were measured, analyzed and compared. Based on the nuclear magnetic resonance (NMR) measurements, the effect of dry density，initial moisture content and soil composition on the drying characteristics of the compacted soils was investigated. The T2 (spin-spin relaxation time) distribution curves at various suctions were measured and used to characterize the moisture distributions in the soils, and the effect of the dry density，initial moisture content and soil composition on the drying process of the compacted soils were analyzed. The results show that the effect of dry density on the drying process is significant only at low matric suction, and for the soils with high matric suction, the effect of the initial moisture content and soil composition becomes important; based on the analysis of the NMR measurements, it is also shown that in compacted clayey sands, the structure and content of micropores are mainly determined by the initial moisture content and soil composition, whereas those of macropores are controlled by the dry density; soil composition has more significant influence on the internal structure and pore-size distribution of compacted soils than initial moisture content.

Water inrush does serious harm to underground engineering. Practice has proved that grouting is an effective technical means to manage water inrush. In recent years, the research on grouting theory for fractured rock mass has become hot, but the fractured hydrodynamic grouting theory develops slowly which was not enough to guide the grouting engineering practice effectively. On the basis of U-shaped diffusion law of horizontal fracture dynamic grouting, the small scale model test system for fracture dynamic grouting with variable inclination is developed. The inclination influence mechanism for grouting diffusion in hydrodynamic conditions is studied by carrying out multi-group indoor model tests and simulating fracture dynamic grouting diffusion process with certain inclination by COMSOL software. The research shows that it meet the U-shaped diffusion law when the fracture is horizontal, and it presents comet-shaped diffusion law under the influence of water head difference and gravity when the fracture existed inclination. Grouting rate and inclination presented parabola-shaped relationship curves under same diffusion effect, and increasing grouting rate can keep the concentration gradient advantage of grouting hole compared with around area. Some suggestions for reference to guide engineering practice are proposed on basis of research results. The conclusions are important complements for the present fractured hydrodynamic grouting theory, and play a positive role to guide grouting engineering practice.

DDARF (discontinuous deformation analysis for rock failure) has successfully realized the simulation on crack initiation, propagation, penetration and crushing of rock mass; but this algorithm only considers the linear elastic constitutive model and doesn’t analyze the nonlinear stress-strain relationship of rock mass. For more accordding to the real rock engineering, and expanding the application scope of DDARF’s nonlinear constitutive model, Mohr-Coulomb strength criterion and the maximum tensile stress strength criterion are respectively used to judge shear and tensile damage for rock mass; the algorithm of ideal elastic brittle constitutive model is analyzed, and is programmed based on VC + + platform. Custom DDARF elastic brittle constitutive model for rock mass is comparatively analyzed with the laboratory uniaxial compression test; DDARF elastic brittle constitutive model is applied to large underground cavern excavation, and compared with the linear elastic constitutive model. Results show that, custom elastic brittle constitutive model for rock mass of DDARF is feasible; this elastic brittle constitutive model can reflect the nonlinear deformation characteristics of rock mass, and coincides with the laboratory experiment well. DDARF elastic brittle constitutive model is applied to large underground engineering, the stability of the surrounding rock mass can be more safely and truly analyzed, and the protective measures of underground caverns can be well guided.

The engineering accidents of anchorage failure often occur owing to the loss of anchorage force of prestressed anchor cable. Complicated coupling effect exists between the anchorage force loss of anchor cable and rock and soil creep. Theoretical foundation and technical means for the design, construction, safe operation management, the control and compensation technique of the loss of anchorage force is provided by building the coupling effect model and establishing the formula of the two. On the basis of common rheological model of rock and soil, coupling calculation model is established based on the equal strain and validated as well by means of theoretical analysis and model research. The findings are as follows: (1) The coupling effect model of anchor cable anchorage force change and rock and soil creep in line with the practical engineering is established. The relationship between the anchorage force loss of prestressed anchor cable and rock and soil creep is correctly reflected. The constitutive equation and relaxation equation and creep equation are deduced, and the calculable relationship between anchorage force change and rock and soil creep is solved theoretically. (2)With the creep equation of the coupling calculation model, the anchorage force loss of anchor cable caused by slope creep effect can be calculated when the material parameters are known. Comparatively analyzing the anchor cable stress data in the practical engineering, we can accurately understand and evaluate the abnormal changes of anchor cable anchorage force to guide the design and construction of practical engineering and ensure the safety of engineering construction process. (3) With the relaxation equation of coupling calculation model, the monitoring data of prestressed anchor cable stress state is arranged and analyzed. With the back analysis of the anchorage force loss data of anchor cable, the creep parameters of rock and soil are analyzed. The creep value of rock and soil according to the material characteristics of creep medium is calculated. The safety and reliability of prestressed anchor cable anchorage engineering are judged in accordance to the creep value to guide the safety operation management of anchorage engineering.

Based on similarity theory, sand is used to simulate surrounding rock and iron wire is used to simulate rock bolt. The paper conducts actual measurement on the change rules of stress distribution, stability and regionalization of surrounding rock under different supporting forces of surrounding rock, different lengths of rock bolt and combined action of rock bolt and tunnel around supporting force during the excavation process of tunnels. Finite element modeling is used to simulate the stress distribution laws of surrounding rocks with different bolt lengths, and the range of surrounding rock plastic zone is acquired based on Drucker-Prager (D-P) yield criterion. The study shows that the carrying capacity of surrounding rock can be brought into full play through combined support of rock bolt and supporting force of surrounding rock. The supporting length of rock bolt should be no less than the external radius size of loose zone without any support. Under the condition of loose surrounding rock, the rock bolt length should be no less than one fifth of the tunnel span; and during comprehensive support process, the supporting force of surrounding rock should be about 5% of the vertical stress of primary rocks. By comparing the simulated results of the experiment and finite element modeling, the latter result is more conservative than the former one.

Taking the splitting sandstone from Yichang as the research object, the paper respectively studies about seepage flow variation rules caused by axial compressions, confining pressures, splitting surface area, concave-convex height different, trace length, 2D projected area of splitting surface, import and export length and joint roughness. The results suggest that the axial compression and seepage flow are in linear increasing relation whether the specimen is filled or not; confining pressures and seepage flow are in a relationship of logarithmic decrement when the specimen is unfilled, while in linear relation as the specimen is filled. Under non-filler condition, the seepage area has a cubic function to the seepage velocity, while there is no influence under filling condition, and at the same time, the concave-convex height difference, 2D projected area have the same rule with seepage velocity. Analysis suggests that the influence on seepage passages of the three factors is far from that caused by fillers; under non-filler condition, the trace length reduces linearly with the seepage velocity; the joint roughness coefficient shows a quadratic functional relationship with the seepage flow whether the specimen is filled or not. These rules can guide the priorities of factors in the seepage measurement, and effectively reduce the measurement of those secondary factors and provide a reference for numerical simulation of seepage.

Designing and calculating of anti-slide pile with anchor cable include calculation of anchor cable tensile force and pile internal force. Anchor cable tensile force directly affects pile internal force. Therefore, anchor cable tensile force computing is crucial in the design of pile-anchor cable structure. On the base of conventional and modified deformation consistence conditions, optimized deformation consistence equation of pile-anchor cable structure is established, in which the effect of the displacement and rotation of pile at sliding surface due to prestressed force of anchor cable on the pile displacement contribution at the i row anchor cable point is considered, and the pile displacement due to the effect of other rows anchor cable prestress Rj0 is removed. Meanwhile, the influence of the incremental horizontal component of anchor cable tensile force on the deformation of anti-slide pile is considered. The deformation and rotation of pile on sliding surface and the deformation made by anchor cables of other rows to point of a row anchor is optimized. Combined with principle of structural mechanics which are virtual work and diagram multiplication method, a calculation programs by Visual C++ was complied to calculate the prestressed force and anchor cable total tensile force through a case study. The results of the three kinds of deformation consistence conditions show that the optimized deformation consistence condition not only makes the anti-slide pile in a good state of stress and deformation in the prestressed stage, but also be suitable for the anchor cable and horizontal plane into different angles. Therefore, the optimized deformation consistence condition makes up the deficiencies of the conventional and modified deformation consistence conditions.

Concrete-faced-rockfill-dam (CFRD) cannot work properly if the cushion material has too much frost heave deformation. Recent researches have shown that: frost heave deformation of cushion material relates to its pore distribution and gradation. In order to reveal the mechanism of the frost heave of cushion material in cold environment, assumptions are adopted that soil particles are ideal spheres and their distribution is completely uniform, a pore distribution model of cushion material is put forward; and the methods are given for determining the equivalent pore diameter and equivalent pore number. Freeze-thaw cycling tests are carried out on one-way oedometer for different pore sizes and different pore quantities of cushion material. Laboratory frost heave tests results show that the frost heave deformation varies with the size and the quantity of the pore. There exists a critical pore size, when the pore is smaller than the critical size, the smaller the pore and the more the small pores, the greater the frost heave, and vice versa. Based on the proposed pore distribution model, a pore distribution index is defined; it is found to have linear positive correlation between the frost heave deformation of cushion material and this index. The results can be applied for the graduation design of cushion material.

Reasonable selection of action combinations is an important prerequisite for ground and foundation design. To determine action combinations based on limited states design for excavated foundations of transmission pole and tower, force characteristic of foundations was analyzed. According to the main three action conditions on foundations of transmission pole and tower, bearing and failure characteristic and easier exceeding limited states of structural system including excavated foundation and ground were studied, and action design combinations of the ground-foundation system were provided. The failure characteristic of excavated foundations bearing too much load is brittle under uplifting or overturning conditions, and fundamental combination controlled by variable load are adopted as required by ultimate limit state design. The relationship curves between load and displacement of excavated foundations are non-steep-fall under downward force condition, based on serviceability limit state design, characteristic or quasi-permanent combinations should be mainly used.

Occurrence of rock mass in certain geological environments forms complex geologic body after a long geological tectonism. This geologic body is composed of rock material of continuous character and various geological structure planes of discontinuous character. Permeability is one of the important parameters affecting the permeability characteristics of complex rock mass. Permeability selected correctly or not is directly related to the reliability and engineering stability of the fractured rock mass seepage analysis results. Laboratory experiment methods are used to determine permeability of fractured rock mass combining with the principle of Darcy's law. Independent development of five pressure chambers of different sizes can measure the permeability of rock specimen in different sizes. Three types of experiment include stable seepage pressure experiment, variable seepage pressure experiment in one size and variable seepage pressure experiment in five different sizes. Experiment can get the permeability of rock specimen which is combined by different fractures and holes under steady flow and unsteady flow and also the permeability characteristics of multiscale rock. This method can determine the changing law of permeability along with the rock size increasing. Conclusions can be drawn from the multiple groups of experimental results. The rock seepage channel increases along with the rock size increasing, thus the permeability increases. But the permeability will be stable until it increases to a certain extent. And also this law can play a guiding significance to engineering.

The vertical frictional resistance generated during the deformation of anti-slide pile can form anti-moment or push-pull resistance, which can contribute to landslide prevention. The impact of the vertical frictional resistance on the internal forces and deformation of anti-slide pile socketed section is studied. On the base of elastic foundation coefficient method “K method” and small deformation assumption, the vertical frictional resistance is considered proportional to the relative displacement of pile and rock mass, then the mechanical model and the bending deformation differential equations of anti-slide pile are established. And the corresponding solution process is derived. The effects of the vertical frictional resistance on anti-slide pile are analyzed by the calculation of anti-slide pile in Majiagou landslide #1. It is found that the counter torque formed by vertical frictional resistance can reduce the pile deformation and internal forces, the shear force is affected by the counter torque mostly, followed by the deformation, and little influence is brought to the bending moment. The anti-slide pile model which has taken the vertical frictional resistance into account can improve the problem of excessive shear force when using the current method, and make the design more reasonable.

Based on the indoor-push-pile model experiments, the toppling failure mode and stress deformation characteristics of the fully-embedded anti-sliding pile are studied. Under the premise of the test similarly relation, the indoor model experiment-pool is established; and from loading to the toppling destruction of the whole process, the deformations of model pile are observed. Arranging earth pressure cells, steel strain gauges, concrete strain gauges, and dial indicators, and using a multi-channel dynamic measuring system to monitor pile strain, the steel strain, the displacement of pile top and the earth pressure, the mechanical characteristics of the model pile is analyzed. It is shown that, the relationship of load and lateral displacement of the pile top could be divided into 3 stages. When the anchorage depth is not enough to the monitoring results, the destruction form of the pile performs as a rigid rotation (toppling failure). The soil pressure of the pile is approximately parabolic. Maximum soil pressure is near the middle of the pile. The moment of the pile is larger around the sliding surface and smaller at the top and bottom of the pile.

Based on Peck formula, the calculation approaching to study the three-dimension soil settlement caused by ground loss during double-line parallel shield tunnel (DLPST) construction is proposed. Considering the influence of first tunnel construction on second tunnel and different excavation face positions of two tunnels, modified three-dimensional Peck formula is established. It was used to calculate soil settlement caused by both the first and the second shield tunnel construction and combined the results, then the total soil settlement induced by DLPST is obtained. It is indicated that this method forecast value almost satisfied the measured value. With two tunnels excavation facing before and after distance of approximation, the maximum soil settlement volume will gradually increase. With the depth of z increasing, the settlement slightly increases and the settlement slot width slightly reduces. When the two tunnel axis level distance (L) is small, the soil settlement volume will be larger, and it is accord with normal distribution. The maximum soil settlement volume will gradually reduce and the settlement curve shape will slowly change by V type into W type as the increase of L.

Rapid setting cement-based grouts are widely used in water rich fracture grouting engineering. In order to study the defusing mechanism in fracture and pressure characteristic of rapid setting cement-based grouts, single planet fracture grouting model text under hydrostatic conditions were carried out using cement-silicate grout and polymer modified grout with different proportions. The diffusing behavior and the pressure variations in different measuring points were recorded to study the laws of hydrostatic diffusion of rapid setting cement-based grouts and the pressure distribution of grout diffusion. Results show that cement-silicate grout and polymer modified grout are similar in diffusing behavior and variation of pressure distribution, while the diffusing pressure of the cement-silicate grout is obviously higher than cement-silicate grout polymer modified grout, which has a relatively longer condensate and solidifying time and is conducive to improving the diffusing distance. The results are used in Zhangmatun iron mine with success in governing the water leakage in rock fracture and stability of the surrounding rock, which has a certain theoretical and practical significance and offers an reference for similar projects.

Four multiple grouting model tests have been finished with slurry tracked by different colors, by using typical porous sandstone selected in Ningdong. It reveals the law of diffusion and filling of slurry in pores, and the relationship between repetitions of grouting and permeability coefficient and porosity of the injected rock and soil mass. The studies found: the filling state of grout is obviously different from others in each single grouting of the multiple grouting test, the slurry of the first time grouting has more uniform filling in the entire profile, while the slurry shows accumulation of filling partly. In the experiment, the more the times of grouting is, the smaller the permeability coefficient of the model material and the greater the filling rate of pores will be. The relation between the permeability coefficient, filling rate of pores and number of repetitions of grouting can be fitted respectively by power function, and logarithmic function. The permeability coefficient of the model material is reduced by 97% after grouting for four times, which means that multiple grouting indeed has an influence on infiltration reduction. According to the test results, a numerical model is established to predict the water inflow of grouting holes and shaft with different grouting times and pore filling rate; and the water inflow of shaft is compared with the actual situation. The results are fairly consistent each other. showing that it is feasible to predict the water inflow by using numerical mode and basis of test results.

The shear tests of bolted jointed rock mass were carried out in the laboratory to study the mechanical behaviors of anchor bolt in the jointed rock mass. In the experiment, rock mass of different strength, anchorage mode and prestress were simulated, meanwhile, the deformation characteristics of anchor bolts were monitored to compare the shear deformation regularity before and after bolting and to analyse the influences of prestress, rock strength, anchorage mode on shear capacity of jointed rock mass. Change of axial force was monitored through the strain gauge to study the axial deformation mechanism and force characteristics of anchor bolts. The distorted anchor bolts were taken out to analyse the relationship between the deformation length and other parameters after shearing test. Several conclusions were derived from the results of above tests: Shear stress vs. displacement curves can be divided into three stages: elastic stage, yield stage and plastic hardening stage, and show a feature of approximate double-linear lines. In elastic stage, the bolts act as “pin”. In yield stage, the axial effect was activated and bolts functioned as both pin and confinement effect. In plastic stage, the bolts did not take the effect of pin, and just restricted the deformation of rock though its axial confinement effect. Shear load vs. displacement curves presented as plastic hardening mode, which means that the toughness of bolted jointed rock mass will be enhanced; and the failure mode changes from fracture mode into yield mode. So that the stability and safety of bolted jointed rock mass were improved. The bolt was sheared as a result of slippage of the joint and was led to additional axial deformation due to lateral deformation, the axial stress increased with the shear displacement. The region of distortion of the bolt concentrated nearby the joint surface and the closer to the joint surface, the more the augment of the axial stress was.

Taking Shaanxi Fuping remolded loess as the object of study, soil samples gone through different numbers of freeze-thaw cycle under a closed system, and variations about mechanical index (cohesion) of soil at the different numbers of freeze-thaw cycle are analyzed. Experiment used spherical template into the determination of relative instantaneous strength and long-term strength of frozen loess. After 4 times, the relative instantaneous strength is the largest, but greatly reduces after 6 times. The relative instantaneous strength significantly increases at the eighth time (but less than the forth time), and gradually becomes stable after 10 times. The largest long-term strength of frozen loess is at the eighth time. The long-term strength at the 6th time and 10th time is similar in the middle level. The lowest relative instantaneous strength is at the 4 th, 50 th and 100 th time. Void ratio and density changes are corresponding to relative instantaneous strength. This kind of change rule has the close relationship with moisture migration in the process of freeze-thaw. The relationship between long-term strength and physical properties is not obvious. It is a synthetical reflection of the internal structure, mineral composition and physical properties.

The zonal disintegration phenomena will appear with the increasing of the depth of underground engineering which are different from shallow cavern. In order to investigate the formation mechanism and influence factors of the zonal disintegration, the true 3D geomechanical model tests for layered jointed rock mass containing soft interlayer have been carried out for the first time. Taking the deep tunnel of Dingji coal mine in Huainan mine area as engineering background, the test adopt model similar material and numerical controlling true 3D loading model test system. The model test results show that: (1) Based on some kind of stress conditions, the zonal disintegration will appear in layered jointed test model containing soft interlayer. (2) Soft interlayer is an important influence factor for zonal disintegration of layered jointed rock mass. Under the same stress conditions, the radial displacements and strains of surrounding rock increase obviously because of soft interlayer. The smaller space of soft interlayer is, the larger range of fracture zone is. (3) The shape of tunnel fracture zone is circle approximately. The shape has no correlation with the soft interlayer and its space. The model test results help to reveal the formation mechanism and influence factor of zonal disintegration, which lays a solid test foundation for further studying nonlinear deformation characteristics and failure mechanism of deep rock mass.

In slurry balanced shield tunneling, how to ensure the safety of construction and to reduce the influence on the environment has arisen wide attention of scholars both at home and abroad. But now it is still in the stage of experience as to the instability mechanism of the slurry shield tunneling excavation and its stability analysis, especially to research on instability mechanism, judgment methods and calculation methods for the complex stratum cases. Regarding the excavation face in slurry balanced shield of the high permeable sand layers as research object, large-diameter modeling test are adopted to do systematical research on the excavation face instability features when properties of sand body and water head heights are different. The results show that: the ground settlement exits hysteresis effect, because it exists soil-arching effect at the same time of the excavation face active failure in the slurry balanced shield tunneling; the development mode of the excavation face active failure in the sandy stratum can be divided into three parts: anhydrous mode, lower water head mode and higher water head mode; it will induce excess pore water pressure during the slurry cake forming and the supporting force imposing; so that excess pore water pressure should be considered in process of the selection of supporting force. This research work has an important guiding sense to the stability of excavation face in the slurry balanced shield tunneling.

Four types of porous material models with different pore distribution patterns are established, and their fractal dimensions of pore distribution (FDPD) are calculated based on both the range and concentration of their pore locations. Then biaxial numerical experiments are conducted to obtain the compressive strength of samples with identical intact strength and different pore distributions and porosities. The results indicate that the failure modes of samples with small porosity or high FDPD conform to the law of 45° angle of rupture, while other samples with low FDPD show asymmetric rupture in oblique section; for samples with identical porosity, the higher the FDPD is, the greater the compressive strength is; the theoretical relationship between sample porosity and its compressive strength proposed demonstrates that the higher the FDPD is, the slower the rate of strength declining with the growth of porosity is; and according to the prediction for compressive strength using damage model, the predicting result is more accurate for porous materials when their FDPD is high, while its accuracy gradually decreases as the FDPD becomes lower. The laws above can be attribute to the fact that a drop in FDPD will lead to more irregular distribution of pores, thus the accumulation of stress concentration in turn will more likely to trigger irregular and easy failures.

Based on the experimental results of intact Brazilian disc of rock-like materials, a set of mecroscopic parameters in particle flow code (PFC) that can reflect the macroscopic mechanical behavior of rock-like materials under Brazilian test are obtained. Then PFC is used to simulate Brazilian test for holed-cracked Brazilian disc (HCBD) specimen. The effect of crack angle and radius ratio on the mechanical parameters of HCBD specimen is analyzed. Compared with intact specimen, the split load of HCBD specimen takes on a reducing tendency, and the reducing extent is closely related to pre-hole and crack parameters. The split load is non-linearly changed as crack angle increasing, but linearly decreases as the increase of radius ratio. In the range of simulation test, when the crack angle is smaller, the hole is the main reason resulting in the main crack initiation; while the crack angle is bigger, the reason of main crack initiation results from the pre-existing crack. When the crack angle is a constant and the radius is relatively smaller, the pre-existing crack is the main reason of main crack initiation; while the crack angle is bigger, the main crack initiation results from the pre-existing hole. Finally, the crack propagation mechanism of HCBD specimen is discussed.

In order to find the effect of total nitrogen on soil physico-mechanical performance, samples have been tested with deionized water and total nitrogen solution with different concentrations in laboratory, and the interaction mechanisms of soil and total nitrogen was revealed by mineral and microscopic analysis. The results show that the total nitrogen has significant influence on soil physico-mechanical performance. Plasticity indices, specific density and effective cohesive strength of samples decrease with increasing of concentration of total nitrogen solution, and the effective friction angle increases; Strain hardening phenomenon appears in the stress-strain relationships, and the variation of stress-strain curves of samples soaked in deionized water and total nitrogen solution are almost the same. The peak shear strength of samples manifests as a trend of decreases at first and then increases with increasing of concentration of total nitrogen solution; with the increase of axial strain, pore water pressure of sample is increased at first and then decreased gradually, and tends to be horizontal direction in the end; while the shear dilatation is evident; mineral composition, microstructure and physico-mechanical performance of soil are affected by the interaction between total nitrogen and soil, including ion exchange, microbial decomposition, dissolution and cementation.

The calculated failure probability for foundation and slope is usually very large, even though the project is proved to be safe in reality. This phenomenon is resulted mainly from the method to estimate variance in practical project. Data of soil index is just property of a certain point rather than the space average characteristic of soil profile. In the process of reliability analysis of geotechnical engineering, the reduction function of variance is the key parameter to transit the point property into spatial average property. It’s the first time that improvement on the method to calculate the no correlation distance put forward by YAN Shu-wang et al. is made, which not only makes the calculation more convenient, but also is a breakthrough of theory. The procedure of calculation of reduction function by the improved method is analyzed, and general regularity of determining reduction function through calculation of no correlation distance is obtained.

Spatial effects of strutted retaining structure caused by the higher stiffness at the corners lead to smaller ground movements near the corners and larger ground movements toward the middle of the excavation wall. In order to analyze the effects of influential factors such as the value of L/He (L is the distance in the longitudinal direction; He is the excavation depth) and excavation depth on spatial effects, a series of a field monitoring exercise including lateral displacement and soil settlement are conducted at two similar subway station deep foundation pits. Field monitored data indicate that the strengthening corner effect can lead to a significant reduction in wall deflection and the plane strain ratio(PSR). The plane strain ratio near the excavation corner is 0.50, 0.61, 0.72, respectively for the bored pile wall, soil mixing wall, diaphragm wall retaining structure. The corresponding value of L/He is 2.50, 6.00 and 4.00 when the plane strain ratio approaches to 1.00. Longitudinal maximum settlement increases first and holds steady with the increase of the value of L/He and the corner effect also increases with the increase of excavation depth. The corresponding value of L/He for the bored pile wall and soil mixing wall is 2.50 and 5.20, respectively, when the maximum settlement achieve stable value. The spatial effects of wall deflection are related to the surface settlement behind the retaining structure.

The salt mines in China have the properties of shallower burial depth, lower thickness, multiple interlayer and lower grade, which will cause more technical risks for construction and operation of underground salt rock gas storage. Based on fuzzy comprehensive evaluation of risk factors of gas storage, the paper has established a hierarchical analytical model of risk evaluation of three risk accidents that storage destruction, gas leakage and surface settlement for salt rock gas storage. The model has been used to evaluate operation risk condition of Jintan salt rock gas storage in Jiangsu Province. The effected weights distribution and risk grade of three risk accidents have been determined. The research results indicate: (1) Lower pressure and operation time of low pressure and stress state of pillar should be controlled to avoid gas storage destruction; (2) Position of casing shoe, sliding of interlayer surfaces, high pressure and damage of pipeline valves should be controlled to avoid gas leakage; (3) The roof thickness, lower pressure and operation time of low pressure should be controlled to avoid surface settlement of gas storage; (4) Storage destruction and gas leakage belong to middle risk, while surface settlement of gas storage belongs to high risk. The effected weights distribution of three risk accidents and risk grade provide theoretical guidance for risk regulation of underground salt rock gas storage in China.

Due to the phasic and continuous rheology of soft rock, failure of surrounding rock and supports of soft rock roadway usually happened. Based on the analysis of interaction effect between roof and support and bottom, the support principle of yielding support with whole section and O-shape control is proposed for the large deformation roadway in deep soft rock. Firstly, the roadway in deep soft rock should be supported with whole section and high strength to control initial deformation. Meanwhile, effective measures releasing pressure of surrounding rock with whole section properly, surrounding rock of roadway would be controlled to good stability, making sure that the soft rock roadway could be controlled coordinately and consistently. Through the mechanical model, relations of plastic zone and surface displacement of the soft rock roadway with supporting force are calculated; the relationship between surrounding rock deformation and support force is negative. Engineering practice showed that the large deformation of roadway in deep soft rock could be controlled efficiently with this support principle. Research results have a good value to similar engineering.

Yongjiang immersed tunnel, built in 1987 and opened in 1995, is a 420 m long road immersed tunnel. It is on the soft soil foundation in a bend of Yongjiang River, which has caused large settlement. Moreover, the severe sediment deposition and 2.67m tidal range in Yongjiang River also have a great influence on the settlement of tunnel. Based on the monitoring data of settlement, the paper analyses the subsoil conditions, tide and desilting’s influence on settlement. And a finite element method based on fluid-solid coupling method is put forward to simulate the long term settlement, and the simulation results are in good agreement with the monitoring data. In addition, the key influencing factors of tunnel settlement, including subsoil condition, trench siltation and siltation and desilting above the element, are calculated and compared. The monitoring data and finite element analysis show that the subsoil condition is the main factor that determines the magnitude of settlement, and the settlement of tunnel on soft soil is much larger than that on other kind of foundations; because of the tidal range, tunnel is subject to an oscillation of elevation which may account for 4%~10% of settlement of operation period; the effect of silting on tunnel is obvious, but regular desilting can only decrease the settlement temporarily and cause the settlement cyclic variation. Although the monitoring data were obtained from a specific project, the conclusions of the study are sufficiently general and may apply in other immersed tunneling projects.

On August 8, 2009, Typhoon Morakot hit southern Taiwan. It carried huge accumulated precipitation of 2,500 mm in 72 hours at Alishan area, and caused catastrophic erosion and landslide. Thus, the hundred-year historic Alishan Forest Railway was suspended due to serious embankment collapses. The rehabilitation principle for these two large embankment collapses followed the natural doctrine. Therefore, the D&B/Mechanical bypass tunnel was adopted to overcome the geological changes and groundwater problem in these two huge landslide areas. The lengths of west portal section colluviums of two tunnels were up to 99 m and 109.8 m, which were the crucial sections of tunneling engineering. The tunnel supporting system design was based on PCCR-system (Rock mass classification of Public Construction Commission) & NATM, and steel pipe roofing, lattice girders, and steel fiber reinforced shotcrete, as well as self-drilling anchors were adopted for increasing the safety and shortening the working days during construction. Currently, two tunnels have been driven through, and the amount of deformation was under control and in accord with safety level. This result indicates that implementation of pre-supporting system in drilling through the crushing colluviums section is effective, and can be used as a reference for the relevant engineering design.

An analytical solution is developed for sliding-toppling complex failure of rock slope, based on the corresponding failure mechanisms and the transfer coefficient method for entire block toppling failure. Moreover, the influences of initial sliding force from unstable set of rock slope and the cohesive force of block base are also analyzed. In order to have uniform expressions, the variables are expressed by the geomechanical parameters of the slope and the serial number of the block in this proposed method. Consequently, the stability of sliding-toppling complex failure of rock slope can be easily analyzed using a Microsoft Excel spreadsheet. This proposed method is applied to a practical rock slope. The results show that the cohesion of block base has significant influence on the failure model of susceptible toppling block, with increasing of the cohesion, the area of block toppling failure increases and the area of sliding failure obviously decreases. It is good agreement with previous research of block toppling failure that the relative angle of block base have significant influence on the entire stability of the complex rock slope; and the safety factor of the rock slope decreases with increasing of the relative angle of block base.

In accordance with the problems of existing methods for surrounding rock pressure of shallow large-span tunnel in up-soft/ low-hard rock stratum, by using DEM (distinct element method) and orthogonal array testing method, the law and sensibilities of the failure mechanism of loose zone and the thickness of overlying weak rock stratum and the joint occurrence influencing on shape and scope of the loose zone are analyzed. In sequence, the sensibilities of factors are as follows in the magnitude order: thickness of overlying weak rock stratum, tunnel depth, angle and distance of continuous inclined joint, distance of horizontal joints in weak rock stratum. Through comparative analysis two failure modes of arch collapse and caving collapse are obtained; the boundary curves are analyzed and fit with linear and non-linear models by using the software ORIGIN, the test results show their boundary curves are power function curve and parabola curve. In accordance with caving collapse loose zone, new formulae for the length of earth surface crack and the soil strip width above the vault are formulated by using the liner least squares method. The errors of the empirical formulae are analyzed. According to the stress transfer principle, a differential trapezoid geotechnical strip is chosen as research object, the formula of surrounding rock pressure of loose zone which considering the joint occurrence and thickness of overlying weak rock stratum is deduced. Case studies show that the results of proposed method are smaller than the results of the existing representative methods.

(discontinuous deformation analysis for rock failure) method was used to research the roadway along goaf of 11302 workface in Zhaolou Colliery. In order to get its failure deformation and control mechanism, DDARF was first used to analyze the crack propagation of single joint anchored specimen under uniaxial compression, then the stimulation result of real roadway was compared with monitoring data from geomechanical model test and field test, to verify its correctness. The focus was on the crack evolution law of surrounding rock in the roadway along goaf. In order to quantitatively analyze the crack evolution in DDARF calculation, two indexes of (crack ratio) and (crack reduction ratio) were defined. Research results showed that the DDARF simulation results were consistent with uniaxial compression test of single joint anchored specimen. In the DDARF calculation of surrounding rock deformation in the roadway driving along goaf, it was shown that the deformation of coal side next to goaf was the largest, followed by roof and integrated coal side, floor was the least, and the monitoring data from model test and field test were both consistent with the result. According to the two indexes and , quantitative analyses was conducted to compare the crack evolution of non-anchored and anchored roadways, and the result was consistent with the deformation trend that is . As the surrounding rock had been seriously crushed, although supporting scheme was effectively, the max crack ratio with anchor supported was still 2.13 times of the . In order to maintain the stability of surrounding rock, the key parts of zoneⅠ and zone Ⅱ should be strengthened besides asymmetric supporting with anchors. For the stimulate result was closer to actual engineering, DDARF method could not only be used to research crack evolution and failure deformation, but also guide countermeasure to control these roadways effectively.

The surrounding rock of underground powerhouse of Xilongchi pumped storage power station in Shanxi is horizontal thin layered, the project has been completed and in operation for many years, it is safe during construction and operation, but before the project starts, there was no successful example for excavation of underground cavern with large span and high side wall in horizontal thin layered. In view of this, this paper based on the project of Xilongchi pumped storage power station, studied the horizontal thin surrounding rock from the view of engineering geology, such as lithology characteristics, structure characteristics of rock mass, mechanical characteristics of rock mass, rock classification of underground cavern with large span and high side wall, deformation characteristics of surrounding rock and so on; according to the research results, excavation and supporting of cavern construction and deformation monitoring of surrounding rock was analysized; mechanics parameters of surrounding rock are inverted on the basis of deformation monitoring results. It verified the previous investigation results and made valuable experience of large underground cavern excavation in horizontal thin bedded geological environment, and provided more technical support for construction of large span underground cavern in the horizontal thin layered geological bodies, has an important guiding significance for large underground caverns construction under this kind of adverse geological conditions.

Aimed at solving the large deformation control problems of surrounding rock masses of steeply inclined roadway in soft-hard alternate strata, field tests, theoretical analysis and numerical simulation and other research methods were applied to analyze the mechanism of deformation and damage for steeply inclined roadway surrounding rock masses under typical condition of alternate strata. The results show the asymmetric deformation characteristic of surrounding rock of steeply inclined roadway in soft-hard alternate strata, evident effect of unsymmetrical pressure, the mutual miss movement deformation features of “roof sliding and floor heave”, obvious floor heave and high possibility of wall caving and roof collapse. The deformation failure was significantly influenced by an obtuse angle region between roadway sections and incline directions of rock strata, which is less confined, ending up with more shear strain. Deformation and failure of lower wall rock mass aggravated compared to the upper wall rock mass. Based on the deformation and failure characteristics of steeply inclined roadway, according to the strategy of asymmetric coupling support, the key position of surrounding rock that may produce deformation discrepancy was reinforced by anchor cable and floor bolt after bolt-net- anchor coupling support and the large deformation of roadway was effectively controlled.

Based on the theories of thermo-mechanics and elastoplastic mechanics, the thermo-mechanical coupling effects of rock and their effects on mechanical and thermal parameters are analyzed. By defining the evolution equations of thermo-mechanical coupling parameters under the damage of temperature effects and mechanics, a new coupled thermo-mechanical damage model with improved Mohr-Coulomb criterion is established, and the numerical implementation in ABAQUS is given. Using finite element method, a typical example was given to verify the importance of the thermo-mechanical fully coupling of rock. Taking a deep tunnel of clay stone as background, the evolution and distribution of damage, temperature and coupling parameters of the surrounding rock are simulated in detail. The results show that the temperature has a great influence on rock properties and damage evolution. Also, the damage by excavation and thermal stress has a great influence on conducting and diffusing of heat. The proposed model can depict the excavation damage, control heat circle and coupling parameters evolution, and may provide a new tool for associated applications.

One major advantage of the numerical manifold method (NMM) is that it can solve the continuous and discontinuous problems in geomechanics in a unified way. It is not necessary to force the mathematical meshes to match the cracks in the NMM, which is very suitable for the simulation of failure process from continuum to discontinuum in geomechanics. During the crack propagation, the relative position relationships between the cracks and the mathematical meshes will be arbitrary; for example, the crack tip may locate in the interior, on the node or on the edge of the mesh. For the same crack, the mesh independency of NMM in dealing with the linear elastic crack problems is studied by rotating and moving the mathematical meshes to construct the relationships and some extreme cases that may have an influence on the results and taking stress intensity factor as the measurement. The results in this study to the NMM show it has little mesh dependency even in treating strong singularity, implying it will be robust in simulating crack propagation.

Directivity of permeability of fractured rock masses is investigated through numerical models with varying flow directions and 3 kinds of aperture distributions. Besides constant aperture distribution and distribution of apertures correlated with trace length of fractures, a log-normal distribution of apertures, which is verified through experiments and is closer to reality due to its allowance of aperture deviations to some extents, is further introduced into numerical models to evaluate their influences on the directivities of permeability. The basic assumptions are that fluid flow only take place in fractures, and that the intact rock is impermeable and linearly elastic. A large number of stochastic discrete fracture network (DFN) models of varying sizes and varying fracture properties are established to examine the existence of representative elementary volume (REV) and to determine the directivities of equivalent permeability, using a discrete element method (DEM), which provides intact rock masses as an assemblage of discrete blocks and the discontinuities/fractures as interfaces between blocks. These numerical simulation results show that REV exists if the equivalent permeability holds steady and the deviations of coefficient of variance (CV) are less than 10%. The distributions of fracture apertures can influence the directivities of equivalent permeability greatly. The directivity of equivalent permeability is remarkable when apertures are correlated with trace lengths, however, the equivalent permeability seems to be isotropic when apertures are log-normally distributed. The reasons may be that when fracture apertures are correlated with trace lengths, the apertures could vary significantly along different fracture sets with different trace lengths, causing differential permeability values in different directions. The inclined angle of maximum permeability and minimum permeability is about 90° when the curves of directional permeability are smooth. The ‘CV’ value is a crucial factor for identifying the directivities of permeability. When the ‘CV’ value is less than 5%, for example with log-normally distributed fracture apertures, the equivalent permeability in different directions is coincident with the mean permeability, which means the rock masses are hydraulically isotropic and can be treated as a continuum. When the ‘CV’ value varies from 5% to 10%, for example with a constant aperture distribution, the permeability trends to be directional for different rotation models. If the ‘CV’ value exceeds 10%, for example with length correlated apertures, the directivities of permeability become remarkable, resulting in heterogeneous characteristics of rock masses. The coefficient of variance (CV) with the value of varying from 5% to 10%, is the critical condition to identify the directivity of permeability of a fracture network.

The discontinuous deformation analysis (DDA) strictly meets balance requirements and energy conservation, and has complete kinematics and numerical reliability. However, the computation time of simulating large-scale geotechnical engineering is too long, especially for solving linear equations; the parallel computing will be a good solution to the problem. Firstly, two contents of non-zero storage in DDA have been described. One is the block compressed sparse row method, and the other is the iterative scheme of non-zero position recording based on the trial-error. Furthermore, we have introduced the block Jacobi iterative method to parallel solving linear equations of DDA, and improved the non-zero storage method. Finally, benefit from the sub-matrices storing, parallel computing of the DDA has been achieved based on Opening Multi-Processing. The improved DDA program has been used to simulate the failure process of the underground caverns; the speedup is obtained to evaluate the parallel efficiency. The results demonstrate that the parallel computing strategy can greatly improve the computational efficiency of DDA for the problems with various sizes. The investigations of this paper will promote DDA to the engineering simulation.

Based on the digital image technology and FDEM (combined finite-discrete element method) proposed by Munjiza, the FDEM system is developed, which can identify the interface of different materials from a rock-like cross section photo. This system provides an innovative method for the investigation on mechanical feature and failure mechanism of heterogeneous material such as rock and so on. The system using digital imaging technology acquisition of real rock material microstructure from the rock section of the image, meshing with mature technology, mapped into FDEM computing grid, thus the deficiencies of the original FDEM in considering the material heterogeneity are overcomed. Using this system, conducting numerical simulations of the Brazil split test, real failure processes of granite are visually observed. The simulation results show that, considering the heterogeneity of rock samples exhibiting asymmetric stress distribution, rock microstructure has an important influence on stress distribution and cracks of rock.

Coupled thermo-hydro-mechanical (THM) process is an important and hot-spot issue. Based on Biot consolidation theory and Morh-Coulomb failure criteria, coupled THM model is built in the framework of TOUGH2 which is a multiphase fluid flow, nonisothermal simulation software. At the same time, a new simulator-TOUGH2Biot is developed with fully coupling between thermal and hydrodynamic processes and partly coupling for mechanics, using mixed integral finite difference and finite element method. Analytical solution is employed to verify the simulator. Finally, TOUGH2Biot is used to numerically analyze the THM response of formations after CO2 injection. The results show that the CO2 injection induces to a quick increase in fluid pressure and corresponding decrease in effective stress. Consequently, there is an uplift of tens of centimeters at the surface. Also, the porosity and permeability are enhanced, which are favorable for dissipation of pressure buildup. The most possibility of shear slip failure is at the caprock above the maximum injection rate location. The second potential failure location is near the surface.

In the application of immersed tube tunnel, water leakage has become a vital problem both in the construction and in the period of operation. For this reason, laboratory experiment is carried out to simulate the seepage of immersed tube tunnel joints of Hongkong-Zhuhai-Macau Bridge by building a full-scale model. By applying infrared technique to the contactless detection of invisible leakage water, monitoring system can collect data of infrared radiation image which is then analyzed with Matlab. Temperature jump method is adopted by analyzing the change of infrared signature, to make the judgment whether leakage happens behind OMEGA or not. Influencing factors on the judgment are analysed at the same time. Results of the experiment show that infrared techniques can be used to monitor sudden leakage of immersed tube joints with the temperature jump method. Relatively large temperature difference between sudden leakage water and structure of joints will lead to temperature jump on the surface of structure. The larger the temperature difference is, the less time system needs to make a judgment. The experiment provides a possible method for application of infrared technique in immersed tunnel and other projects. Feasibility of application of infrared technique in immersed tube joints is researched.