The stability analysis method of underground energy storage cluster is developed using the principle of minimum plastic complementary energy and unbalanced force, based on the strict definition of structure failure and its logical description with set concept presented in deformation reinforcement theory. In the framework of non-equilibrium elastoplastic mechanics, the classic finite element method is extended to the analysis for post-failure state of structure, where the plastic complementary energy norm serves as the criterion of global stability while the unbalanced force and its development indicates the pattern and path of destruction. The cluster stability and chain destruction of double-cavern cluster under different distances are emphatically studied. Results of stability analysis and chain destruction simulation for Jintan oil and gas storage cluster in rock salt deposit is presented. The result shows that the unbalanced force and plastic complementary energy are suitable for quantitatively evaluating the stability of underground storage cluster. Deformation reinforcement theory provides quantitative and practical analysis method for the study of global stability, cavern interaction and space-time evolution of destruction of underground energy storage cluster; and it which can be used for the research of disaster mechanism and protection measures.

Uniaxial cycling loading and unloading tests of rock salt were performed on MTS, and the results showed that loading and unloading progresses strengthen the linear character of curves; the main part of curves is linear. Followed with the step, deformation modulus is in slightly rising trend. The coefficient of variation of deformation modulus of unloading curves is 8.05%, while that of loading curves is 7.45%. So the deformation features can be characterized by the average deformation modulus of loading and unloading curves. In every step, the unloading deformation modulus is higher than the loading’s, while the loading Poisson ratio is higher than the unloading’s. Compared with uniaxial test, the loading and unloading deformation moduli are higher. Based on the analysis, the constitutive relation under simple stress state has been built. In every step plastic hysteresis energy was calculated, and the result showed it increased by the step. The analysis showed the deformation parameters under loading and unloading test are much more regular and consistent than those under uniaxial test, these parameters can characterize the deformation of underground engineering of rock salt better.

In this paper, acoustic wave technology was used to study the damaged characteristics of salt rock under uniaxial loading and the effect of damage on dissolution to reveal the parietal injury dissolved characteristics in salt cavity construction period. The study shows that: when the stress increases, the lateral velocity, unlike axial velocity gradually decreasing, decreases rapidly when reaching the ultimate strength. The greater is the pressure on rock salt, the faster is the salt rock dissolving. Based on the analysis of rock strength theory and damage theory, we conclude that the stress damage of salt rock is caused by the increase of micro-cracks resulting from crystal dislocation with each other. The damage variable and stress are closely related. The rock salt dissolution rate increases with the damage variable growing.

An analogy recipe used for model test studying of rock salt gas storage, which can simulate the features of rock salt such as lower bulk density, lower modular ratio and larger rheology deformation. Using geomechanic model test technique, Jintan salt mine’s long-term stability and the cavity’s deformation and stress distribution under cyclic internal pressure are studied. A constitutive model which considering damge of rock salt is deduced and employed in Jintan rock salt gas storage’s numerical computation. The result from the numerical computation is checked by the one from the model test. The study indicates that the model test technique is very effective in studying of gas storage’s long-term stability. The damage evolution of rock salt and the creep deformation of the cavity under cyclic loading-unloading is obtained. The result can be used to guide the constrution and production of gas storage in rock salt in China.

The Jintan oil-gas storage of salt rock in Jiangsu Province is a demonstration project; and the similitude material is made up of fine iron, barite powder, quartz sand, rosin and medical alcohol. According to principle of similitude and measured physico-mechanical parameters of salt rock, mudstone and salt rock interlayer of oil-gas storage of Jintan, the uniaxial compressive test, triaxial compressive test, direct shear test and Brazilian test under different material proportions are carried out. After comparing and analyzing the bulk density, Poisson’s ration, elastic modulus, compressive strength, tensile strength, cohesion, internal friction angle, deformation and strength failure features of model similitude material with that of prototype, the similitude materials for salt rock oil-gas storage medium are attained, which supplies reliable similitude model material for oil-gas storage geomechanical model test.

Determination of permeabilities of low permeability rock (≤10－18 m2) under different stress conditons and temperatures is the basis of stability evaluation in geological disposal of radioactive waste，underground gas and oil storage tanks and construction of deep cavern groups. Based on the developed low permeability test equipment(T-M-PTS)，gas transport properties of typical Jinping marbles are studied under different hydrostatic pressures and temperatures. Based on microcrack linkage model, evolution of permeability is also studied theoretically. Some results are achieved：(1) Klinkenberg effect is remarkable when gas transport through dense rocks, and should be considered; (2)based on statistic theory and percolation theory, a 3-D penny-shaped microcrack moded has been developed to predict and investigate the evolution of permeability due to microcrack closure in compressive regime; (3) permeability decreases as hydrostatic stress increases because of the decrease of porosity under compression, and permeability decreases faster at the first stage of compression; and (4) permeability decreases from 21.9×10－21 m2 to 3.9×10－21 m2 as temperature increases from 15℃ to 40℃ because of the decrease of elasticity, which lead to decrease of porosity under the same hydrostatic stress.

Salt cavern gas storage plays an irreplaceable role in shaving natural gas peak and ensuring the safety of gas supply. But when the design life of salt caverns gas storage is over, it will be discarded and finally collapse, which would cause serious ground subsidence. It is very important to find the rule of the ground subsidence. Considering the deficiency of the present numerical analysis software in analyzing the ground subsidence, 2D-Sink, the special software which is used in numerical simulation of the ground subsidence after the damage of the salt cavern gas storage has been developed. And the software has the function of dealing with the broken rock. Through operating the 2D-Sink, 6 numerical models are built. The rules of the bedding effect, rock inclined effect; fault effect and ground subsidence of multi-cavern have been studied. To compare the ground subsidence curves of multi-cavern with the superposition ground subsidence curves of single cavern, it is proved that the superposition principle of ground subsidence is correct. The research results can provide one of the basic theories for the control of ground subsidence disaster after the salt cavern gas storages have been discarded.

In the natural gas storage engineering, the casing depth in the residual brine and the velocity of ejecting brine decide if the natural gas overflows from the salt cavern during injecting gas to eject brine. It is a difficult problem to adjust the velocity of ejecting brine under different casing depth in the residual brine and decrease the danger of the natural gas from the cavern. This technical problem is researched. The flow field of gas storage in the process of injecting gas to eject brine is modeled by the flowing theory of fluid. The maximal velocity of brine in the outside of casing is obtained. Based on the theory of the rising velocity of natural gas bubbles in the brine, the permitted velocities of ejecting brine under the different depths of residual brine are determined. The research result gives the technical support in the gas storage engineering of salt rock.

In order to depict the hardening and softening behaviours of clay, a new elastoplastic damage model with Mohr-Coulomb criterion is presented in the framework of the irreversible thermodynamics and nonlinear continuum mechanics. Furthermore, damage evolution equation is suggested based on the defined damage potential. Based on the developed numerical code, parameters for Boom clay elastoplastic damage model are obtained according to undrained triaxial consolidation tests by back analysis. The numerical simulation under various stress states shows that the proposed model is able to effectively depict the main features of mechanical behaviors of Boom clay.

The existence of indissolvable interlayers leads to many adverse effects for building salt cavern storages by solution mining. It is an urgent technical problem that how to forecast and control the collapse of indissolvable interlayers. The problem is the research background of mechanism of interlayer collapse. A mechanical model for interlayer collapse study is established and solved by theory of plate and shell. Based on the solution, the mechanisms of collapse caused by partial failure and integral instability are analyzed. And then all the mechanisms of collapse are summarized. Finally, a method for calculating limit diameter of interlayer is proposed. The conclusions of the research have significant meaning for forecasting and controlling interlayer collapse in solution mining.

Energy storage is greatly demand by the national strategy, so large-scale underground salt-rock gas storage constructions had been begun to build. There are many characteristics of domestic salt rock gas storage on geology, such as bedded salt rock is thin, has much interlayer, and the geology is more complex. It is difficult to build and manage it. So it is more significant to carry out researches on assessing the risk of salt rock gas strorage for the theoretical research and engineering technique. Performance-based design (PBD) method has been imported into risk analysis to classify the salt rock storage risk level in current situations. Volumetric shrinkage of the salt rock storage is regarded as individual factors on classifying the risk level. Numerical simulation is carried out to evaluate the creep of a salt rock gas storage in China on different gas pressures. Risk level under different gas pressures for different times on the storage is obtained. The results also verify that the method proposed is reasonable and valid for salt rock gas storage risk analysis.

Taking the Jintan rock salt gas storage in Jiangsu Province of China for example, regional tectonic and engineering geologic setting are analyzed. The mineral form, fine composing and hydrophilicity of mudstone interlayer between rock salt are studied by XRD test, granularity test and slaking test. The results are as follows. Mudstone interlayer are composed by interbedded mudstone and inter mudstone of rock salt. Interbedded mudstone of rock salt is thick with connected distribution. Inter mudstone of rock salt is thin with disconnected distribution. Clay is the main mineral of interbedded mudstone of rock salt. The illites/smectite mixed-layer mineral is the main formation of clay in interbedded mudstone. Granule particle is main in interbedded mudstone. Interbedded mudstone slakes by stratification bedding and little expansion. The character of interbedded mudstone affect the safety and running of Jintan gas storage.

Because of the properties of salt rock and particularity of the geographical location of gas storage, there are few studies of the THM coupling model for gas storage in salt rock. Based on the work of THM coupling model of J. Noorishad and C. F. Tsang who is in charge of DECOVALEX in U.S., the mathematic THM-damage coupling model is derived under geostress, injection and production gas pressure and temperature, according to our experimental data of salt rock and our study of gas seepage regulation of gas storage in salt rock with interlayer. In this model, thermal injury effect of salt rock and the Klinkenberg effect of gas seepage are considered. The effect of gas flow along the interlayer surface on the seepage regulation is also considered. Based on it and according to the construction of Jintan gas storage, numerical technology is adopted to get the gas seepage, temperature and stress distribution regulation considering the coupling and uncoupling THM effect, in the process of injection and production. From the detailed comparative analysis, it is concluded that the coupling effect is very significant for gas storage in salt rock with interlayer. This study provides an ideal and premise for the safety and practicably analysis of gas storage in salt rock. This study has an important theoretical and practical meanings.

In order to resolve the treatment of inrush of high-pressure water and reinforcement in deep underground engineering, combined with the reinforcement mechanism research of chemical grouting material, not only the feasibility of a new type of chemical grout has been studied, but also the experimental research on properties of new types of chemical grout, such as mobility, penetrability, strength, anti-brushing performance, water genotoxicity and so on are performed in the laboratory; therefore the physicochemical characteristics of has been analyzed; the proper proportion of new chemical grout and its relative specifications have been given. In addition, based on a project case under water-inrush hazard, the field experiment has also been carried out; contrasted to other types of grout, such as cement with super fine slag, cement and water glass double grouts, and urea resin harnstoffharz, the applications and advantages of this chemical grout on inrush of high-pressure water controlling has further been proved. It is shown that this new chemical grout is quick reaction, high strength, well scouring resistance, innocuous and excellent performance of permeability and hydro-expansiveness. Ideal grouting effect has been reached for its good controllability and pumpability in the field test, contrasted to the styles of cement grouting material and some common chemical grout material, it has advantages of rapid transportation, convenient proportioning and simple technology; the conclusions obtained will devote to the following studies.

The significant particle size grading and particle breakage of deep soils are two major characteristics of super-high dumping sites. The particle breakage and shear strength of different coarse-grain contents were studied based on the refitted large-scale direct shear apparatus. The experimental results of particle breakage indicated that particle breakage index was very small when upright stress was lower than 400 kPa and increased obviously with the increase of upright stress that was higher than 400 kPa. The particle breakage index was very little at coarse-grain contents less than 46.0% and increased significantly according to the increasing of coarse-grained contents which was more than 46.0%. The relationship between particle breakage index and upright stress could be expressed by hyperbolic curve. The particle breakage of soil sample ,which was soaked for a long time in water, was remarkbale. The experiments studied on shear strength showed that the shear stress-strain curves were micro-softening model or micro-hardening model under low upright stress and were slight-softening model at higher upright stress when the coarse-grain contents was equal to 24.0%. At coarse-grain contents equal 78.0%, the shear stress-strain curves were softening model under low upright stress and slight-hardening model at higher upright stress. The shear strength envelope expressed nonlinear under higher upright stress. When the particle breakage index was small, the internal friction angles which were respectively fitted in the upright stress lower than and higher than 400 kPa changed little. With the obvious increment of particle breakage index, the internal friction angle of upright stress higher than 400 kPa was much smaller than that of upright stress lower than 400 kPa.

Mine water inrush is one of the most threatening disasters in mining engineering, especially in underground coal mines. How to distinguish the source of mine water inrush exactly and quickly is not only the major content of mine hydrogeology works, but also the important foundation of mine water prevention. In the source determination of mine water inrush, it is essential to consider the importance of the indexes of chemical elements of water. Based on the Bayes’ multi-group stepwise discriminant analysis theory, six indexes of chemical elements, such as Na+ + K+, Ca2+, Mg2+, Cl-, SO42- and HCO3-, are taken as the key factors. The total of 35 different water sources examples from a real mining area are chosen as the training and testing samples, a forecast model for distinguishing the source of mine water inrush is then established. The results obtained by the forecast model in case studies are well consistent with the practical situations, so as to prove the utility and efficient of the method. It may provide a new method for the water source determination of mine water inrush.

At present, when studying the theory of solution mining as well as the stability of solution chamber, the main method, adopted by domestic and foreign scholars, is based on exploitation of small-size rock salt simple. Therefore, it is necessary to create large-size rock salt with similitude materials to faciliate simulation of the entire process of solution mining, and of the stability of solution chamber. Specific tests have been carried out on dissolution property and mechanical property of molded rock salt, which is made up of salt powder with high pressure treatment. The experiment indicated that the rate of dissolution kept steady when the suppressing-stress are 40 MPa, 60 MPa and 80 MPa, while the ratio of molded rock salt are 2.15 times, 1.84 times and 1.77 times as quick as that of natural rock salt whilst the angle is 0°, 90°and 180°respectively. The conclusions are drawn that the strength of molded rock salt is proportional to the suppressing-stress and the strength of dry-molded rock salt corresponding with that of rock salt when the suppressing-stress is 80 MPa; the strength of molded rock salt decreases after water uptake while that of rock salt is lack of change. Therefore, under the effect of proper suppressing-stress, it is justifiable to reach the conclusion that it is practicable to substitude rock salt with molded rock salt stressed by salt power in entire-process test running and theory study of solution mining, as well as experiment study of the stability of solution chamber.

According to the distributing characteristics of water content and ground temperature along Qinghai-Tibet Railway, triaxial compressive experiments of frozen sandy soils from Qinghai-Tibet plateau were conducted with 30%-80% (supersaturated)water contents and temperature ranging from -0.5℃ to -6.0℃. The results show that with increasing water content, strength of sandy soil nonlinearly increases when the testing temperatures is -0.5℃; and it has a minimum value with the temperature of -1.0℃, whereas when the temperature is equal to or below -2.0℃ it gradually decreases. Based on the relationship between the strength and normal stress under different temperatures, yielding criteria of Mises and linear Mohr-Coulomb is used to describe the yielding situation of sandy soil, respectively.

In Cook rigidity criterion, it is taken into account that the release of the elastic strain energy in test machine will affect the burst of the rock sample. On the other hand, the residual energy method based on the elastic energy exponent and the impact energy exponent takes the influence into account that the elastic energy stored in the rock acts on the burst of the rock sample. In view of the fact that the test machine and the rock interior releases the elastic energy respectively with the burst of the rock sample, it is suggested that both sides be combined, i.e. the influence exerted on the burst of the rock sample through the elastic energy releasing between the test machine and the rock interior be considered comprehensively, it is so-called the comprehensive rigidity and comprehensive energy criterion of the burst of rock. This can determine the position of starting point and end point of the burst of rock more reasonably, give the calculation relationship of the elastic energy releasing amount of the test machine-rock sample system (i.e. the general rock body system) with the burst of rock, and can express these relationships through geometry form.

Considering the practice of embankment construction, the experimental device and experiment method to prepare experimental samples with different compactnesses to measure water permeability of sands soils or clay under compressive load changes was manufactured. According to the measurement of variations of water permeability under compressive load or unload in different compactnesses, the rule of water permeability of sand soil was revealed due to be influenced by different compressive loads and different compactnesses. It is shown that the compressive load and compactness both influence the water permeability of the sand soil greatly; but the factor of compressive load influences, its water permeability more greatly. Especially for the low compactness soil, the influence of the load on the permeability is very obvious.

According to two logical judgements, the relation of the semi-infinite plane strain problem and semi-infinite spatial problem is found through analyzing the classical answer of wedge, semi-infinite plane, cone and semi-infinite spatial etc. The Flament answer of semi-infinite plane strain problem and the Boussinesq answer of semi-infinite spatial problem are confinable from the relation. Based on a comparison of stress and displacement components of the semi-infinite elastic foundation, the elastic finite depth foundation with rigid constraint at the bottom, and the elastic finite depth foundation with smooth rigid supporting constraint at the bottom under infinite uniform pressure on horizontal surface, it is concluded that the elastic finite deep foundation model with rigid constraint at the bottom is more rational than other two models.

After triaxial compression tests to fissured loess samples with different features and different angle values of fissure in samples under different confining pressures, the failure characteristics are described; and deformation and failure rules are generalized by means of measuring the distortion of mesh lines and fissure marked in side face of fissured loess samples. Results of tests show that there are 2 types of failure which are brittle failure and plastic failure; and that there are 5 modes of stress-strain curves with very strong softening, strong softening, softening, perfect plastic(or weak softening, weak hardening) and hardening. The different failure modes are related to such factors as spatial location and feature of fissure in samples and confining pressures of tests. And the position of failure plane in fissured loess is influenced by the deformation modes of samples and fissure in samples and the border of top or bottom pervious stone.

Working mechanism of the geocell reinforcement was discussed. Based on the deformation responses under the load, the geocell reinforcement was treated as a beam on Winkler foundation while analyzing. Then the theory of beam on elastic foundation was employed to propose the deformation control differential equation, which could consider the effect of the horizontal resistance between the geocell reinforcement and the foundation soil; and a power series solution for this equation was given. And then a deformation calculating method for the geocell reinforcement under the point load was proposed, which was a beneficial result to study the settlement calculation of road embankment reinforced by geocell. Finally, to verify this method, a model test was employed. The comparative analysis result shows that the value of the vertical deformation of the geocell reinforcement will be exaggerated if the effect of the horizontal resistance is neglected; but while this effect was considered in analyzing, the theoretical curve is much closer to the measured value.

Bearing capacity of rock foundation is an important index in civil engineering. It is based on the uniaxial compression strength R of saturated rock for most civil engineering, and also based on the eigenvalue P of plate loading test for important engineering. Thus, the two methods must have some relativity. It is indicated in the practices that the R method is simple and easy for handling; but R represents characteristics of rock materials which is quite different from the condition of the engineering rock mass. Plate loading test is carried out under the semi-infinite condition; it is more close to the engineering practice. Therefore, the P method is more reasonable than the R method. This article establishes the relativity of P-R as well as the strength characteristics under surround compression on the basis of summarizing 43 plate loading tests results and three groups of uniaxial compression strength tests results on the same position, and collecting 248 groups of triaxial compression test results in Chongqing area. By demonstrating the relativity of P-R，the article brings forward an important conclusion of taking rock saturated uniaxial compressive strength of the standard value of 1.5 times the characteristic values as a foundation bearing capacity of the important conclusions， so as to provide an important reference for optimization of bearing capacity of rock foundation.

The practical application of seepage force concept to the piping problem research is described. According to the limit equilibrium between seepage force and buoyant weight of soil grains, the formulas to compute piping critical gradient for various grain sizes in sandy gravels of piping soil are derived. And then they are verified by many data of piping experiments; it is shown that these formulas are reasonable and responsible.

When elastic impedance is used in practice, it needs to estimate the incidence angle, (whereθ is the incident angle) may exceed unity because of the existence of errors, which makes elastic impedance inversion extremely unstable. Used substitute for (Whitcombe et al., 2002) derived the extended elastic impedance, improved the stability of elastic impedance inversion. Based on the three term Zoeppritz equation (Aki and Richards, 1980), this article improves Whitcombe's extended elastic impedance. The improved extended elastic impedance increases the computational precision.

The deformation failure mechanism of coal and the effect of initial cracks and closure on coal strength. The research results show that the process of coal failure can be divided into five stages, including damage degradation, quasi-linearity, damage steady evolution, damage accelerating evolution and post-peak softening. With closure of massive initial fractures and void structures in the Shenfu’s coal, the strength and the elastic modulus of coal will be improved significantly. So, it’s more reasonable to simulate the excavation process by using elastic modulus which has been improved. Acoording to the numerical simulation results, the reasonale thickness of supporting is chosen as 20-25 cm.

Experimental study of stress-strain relationship of normally consolidated intact soft clay in Hangzhou under undrained fixed shear of principal stress direction and monotonic rotation of principal stress axis had been done, which was used to reflect the soil properties response to the monotonic rotation of principal stress axis under real engineering conditions. It was found that under the fixed principal stress direction shear, strain components at different principal stress direction had quite different development levels, but the values of most samples’ critical octahedral strain were comparatively close. Meanwhile, when the octahedral strain reached 5%, the development level of most samples’ shear strengths had been closed to, even exceeded 90%. When additional stress path of monotonic rotation of principal stress axis was added to fixed shear of principal stress direction, samples critical strain components would not change obviously as long as the final failure principal stress directions were similar. But the direction of principal stress increment and the principal strain increment showed non-coaxiality during the rotation of principal stress axis; and with the development of shear stress level till critical state, such non-coaxiality became more obvious. The experimental results showed that due to the existence of initial anisotropy and viscoplasticity, it was not proper to describe the stress-strain relationship during and after rotation of principal stress with associated flow rule.

The concept of effective stress is mostly used in hydro-mechanic coupling study, while it is difficult to determine the values of Biot’s coefficients. A test system is developed to study the evolution of Biot’s coefficients in cracked rock materials induced by deviatoric stress. In the plastic deformation phase of triaxial compression test, some loading-unloading cycles of axial stress were carried out at different levels of axial strains. After injection and squeeze water into/out of the specimen at the end of axial stress unloading process, the deformation is recorded during the loading-unloading cycle of pore pressure. The Biot’s coefficients in axial and lateral directions are calculated based on the method proposed by Shao. The evolution of axial and lateral Biot’s coefficients at different levels of axial strains is presented in a series of confining stresses; it is found that: 1）the property of Biot’s coefficients is anisotropic, it is reasoned that the cracks in the specimen are grown along the direction of maximum normal stress; 2）the axial and lateral Biot’s coefficients are increased when axial strain increases, the increasing of axial strain leads to the propagation of cracks, consequently causes the Biot’s coefficients augment; 3）the values of axial and lateral Biot’s coefficients under low confining stress are greater than the one under high confining stress, the reason is that the failure style is changed with confining stress.

The Drucker-Prager yield criteria are widely used in geotechnical engineering as modified models of Mohr-Coulomb criterion. Great differences may be made between results with different Drucker-Prager yield criteria. It is important to select a proper Drucker-Prager yield criterion in geotechnical engineering analysis. The range of Lode angle of Drucker-Prager yield criterion is too limit to reflect more stressed conditions and should be enlarged from －30°to 30°is pointed out. Studies of section how to select a proper Drucker-Prager yield criterion are made based on stability analyses of a certain slope and that of dam #12 foundation of the Xiangjiaba Project. Studies show that more reasonable results can be achieved if the Lode angle of Drucker-Prager yield criterion selected can reflect the stressed condition of important parts which play important roles in maintaining stability of dam foundation or slope; and it is necessary to enlarge the range of Lode angle of Drucker-Prager yield criterion.

Based on the Biot’s theory of poroelastodynamics, the vertical vibrations of a massive, rigid cylindrical foundation embedded in single-layered saturated soil were studied. At first the governing differential equations of saturated soil were solved by Hankel integral transform. Then, considering the mixed boundary value conditions at the interface between the foundation and the soil, the dynamic reaction at the base of foundation and along the side of foundation were obtained. Subsequently, the vertical displacement amplitude of the foundation and the equivalent dynamic impedance of the saturated soil overlying bedrock were derived by combining the dynamic equilibrium equation of the foundation. Selected numerical results indicate that the displacement amplitude and the dynamic impedance show obvious fluctuations, and that the soil layer thickness, the depth ratio of the foundation, the mass ratio of the foundation and the soil permeability have significant influence on the vertical vibrations of embedded foundations.

Property of structural surface is described by tangent stiffness and secant stiffness. The effect of initial rigidities of structural surface, frequency of stress wave and the ratio of normal and maximum allowed fracture closure of structural surface on transmission coefficient is studied. Block response of structural surface under nonlinear deformation is simulated by continuous- based discrete element method(CDEM). The results show that the stress wave propagation in rock mass is a process of both wave propagation and block response; the propagation of stress wave and response of stress wave are influenced by structural surface; stiffness variation of structural surface is effectively reflected by characteristic frequency. The computational expressions of characteristic frequency are given. The findings in this paper can be useful to the detection of rock mass structural surface.

In recent years, the dynamic compaction replacement (DCR) is widely used to consolidate soft soil foundation for its short period and simple construction and so on. But the reinforcement mechanism of DCR hasn’t been well researched; theoretical study is far behind engineering practice; so it is hard to build up the design theory and method. Based on the Haiman expressway project in wetland and by using the finite element method, the mechanism of DCR reinforcing expressway soft roadbed in wetland is studied so as to give some reference to designers.

The Problem of how to calculate the earth pressure for the earth-strip neighbouring excavations is run against frequently in excavation engineering practice; but there is no calculation method in the existing criterion of excavation for the moment. First, the retaining and protection forms between neighbouring excavations are classified and put together, the affirming principle of the width between two excavations is put forward; then, the superposition method on Coulomb’s earth pressure theory is presented; and the calculation formulas of the active earth pressure coefficient and earth pressure are derived and presented for clay and non-clay under differrent gradients and ground load, and the idea of the critical width and the calculation formula of reducing coefficient of the earth pressure of the earth-strip are also presented. The total and distributing earth pressure of earth-strip for different soils, different gradients and ground load can be calculated simply by the superposition method, the idea of the critical width and the calculation formula of reducing coefficient of the earth pressure of the earth-strip. Finally, two engineering examples are given to show that the retaining and protection structures generated by the method and the formulas are safe and rational; the method and the formulas can be for reference by similar excavation engineering.

The buried depth of Liziba tunnel is shallow, and surrounding rocks at entrance and exit are soft. Many houses and one water tower have been constructed over the tunnel. According to the engineering condition, the ahead ductile, I-steel and shotcrete are used in the first support, grounting and inverted arch are constructed at tunnel bottom, and the semicircular arch of reinforced concrete is used in the second lining. To ensure the construction safety and the building stability during construction, the stability of the most dangerous section is calculated, and the calculated stability factor is 1.9. The settlements of the surface, the water tower and the houses are monitored, and the arch settlement and horizontal convergence of the side-wall are monitored, too. The results show that settlements of the surface and the houses are little, the settlement of water tower goes down equably, and the deformations of arch and side-wall are little, too.

Based on the monitoring data of earth pressure of several retaining walls in mountainous area, the distributing rules of earth pressure of retaining wall were studied in detail. The tests results show that: ①The increase speed of earth pressure in different depth was different. ②The value of earth pressure is intervenient between the still earth pressure and vertical earth pressure. It is closer to the still earth pressure below the depth of three-quarter retaining wall, and is closer to the vertical earth pressure above the depth of one-half retaining wall. ③The earth pressure behind retaining wall is nonlinearly following the depth of retaining wall. The curves can be considered as double line. The resultant earth pressure is about 2.5 times of resultant Coulomb active earth pressure and 0.3 times of resultant Coulomb passive earth pressure. The height of action point of resultant earth pressure is 0.38 times of the retaining wall. The earth pressure changes with time, and its rule is: the earth pressure increases first, and then decreases with time; furthermore, the change range is rather large.

Wucunshan Tunnel of Xiamen which is designed as shallow large span structure needs to go through dense buildings in Punan territory, and construction difficulties is unusual both at home and abroad. By in-situ building lifting test and monitoring, two levels of building lifting by grouting can be seen: the first level is controlling and cutting building subsidence, the second is named building lifting strictly. The in-situ lifting tests show that the first level can be achieved with dynamic tracking and retrieving grouting successfully, whereas the second level requires much more refined grouting techniques. On one hand, the fulfilling of building lifting must be on the premise of the first level of retrieving grouting, finishing wall for grouting, and enforcing foundation soil. On the other hand, it depends on adequate grouting technologies, grouting amount, pressure, arrangement of grouting holes, holes and depths, etc. Related monitoring results make clear that land lifting is standing out, and building subsidence is distinctly slowed down, however, building lifting is only light and fluctuant, and finally trend to subside. And they also show that there is great difference between land and building liftings, only large range, stable, uniform, undissipated land lifting can make safe and effective building lifting, By analytical and numerical methods, lifting grouting parameters will be optimized and gained, and building lifting deformation can be predicted, which can generally meet the engineering needs.

By using the method of preloading as vertical reaction, the field shearing test of heavily weathered hornstone side slope rock mass are carried out under the natural and the saturated condition. the shear stress – shear deformation relation curves under different normal stress levels and shear strength parameters are obtained. Based on the results of field shearing test, the effect of strength and deformation on mechanical-hydro coupling process and the change rule of the shear stress along with different normal stresses and the shear stress-deformation relation curves characteristics are analyzed. The test results indicate that, the peak shear strength and the yield shear strength increase with the increase of the normal stress; and the change of water content has not influence on the change rule of the shear stress along with different normal stresses. The shear strength decreases with the increase of water content; and it is especially sensitive under the low normal stress. Attenuated function for cohesive force of water is more obvious, and simultaneously has enlarged the rock mass amount of deformation and lengthened the rock mass distortion process. Modulus of compression of rock mass can be estimated by vertical deformation tested in the field shearing test.

Based on a lot of dynamic triaxial tests, the variation laws of dynamic stress-strain, dynamic elastic modulus and damping ratio of structural soft soils were studied; meanwhile, the influences of vibration wave, frequency and consolidation ratio were investigated. It is concluded that the influence of vibration wave on the type of dynamic stress-strain is not evident; the value between the maximum dynamic modulus and dynamic shear modulus is 2.5 times or so. The effect of frequency on the structural soft soil is evident; and there is a threshold vibration frequency. The maximum dynamic modulus decreases with the consolidation ratio increasing as the confining pressure is less than structural yield pressure; and when strain exceeds a certain value, the maximum dynamic modulus decreases with the consolidation ratio increasing. At a lower strain and deviatoric pressure, the higher the consolidation ratio is, the larger the damping ratio is; and when strain exceeds 0.004, the consolidation ratio increases, meanwhile the damping ratio decreases as the strain value increases. The conclusions can provide a useful guidance for the engineering application.

The composite support pattern of soil nails and prestressed anchors are commonly adopted in the projects of deep foundation pits. By using the FEM program of PLAXIS and choosing appropriate material models, the support pattern of soil nails and prestressed anchors and the pattern of soil nail walls are analyzed. Then the slope stability of foundation pits is studied; and it is shown that the location of prestressed anchor is vital in the composite support pattern. The closer the anchor is to the top of the slope, the more useful the anchor is and better the effect is. Compared with support pattern of soil nails, the displacement of soil nails and prestressed anchor tends to reduce. However, the number of anchors and the value of prestress have some effects on the final result; and the localized inclined ramp is beneficial to control the maximum horizontal displacement of the pithead.

Experimental studies were undertaken on an expansive soil from Nanning area in order to establish relationship between shear strength indices and cyclic drying and wetting parameters. It is shown that the shear strength of expansive soil decreases with increasing number of cycles and finally reaches to a constant state. The value and cyclic number of the constant state reduce with increase of amplitude of variation of water content. Furthermore, the mercury intrusion porosimetry (MIP) test was applied to determine the pore size distribution curve of expansive soil during wetting-drying cycle. The MIP test results show that the bond of soil is irreversibly damaged by cyclic drying and wetting, which leads to increase the volume of pore. In high water content, volume of outer-aggregate pores increase with number of cycles; while in low water content, volume of intra-aggregate pores will increase. As a result of degradation of microstructure, the shear strength of expansive soil quickly decreases.

Organic polymer material SH, as an economical and environmentally solidified material, possesses useful properties in control of desert. Sand with different densities is solidified by SH material of different consistencies with different means of reinforcement. After being solidified, microstructure of the sand will be changed; and accordingly the mechanical property will change also. Graphics manipulation has been used to count and analyze the stereoscan photographs of solidified sand. Multivariate stepwise regression method has been used to calculate the correlation of microstructure indices and the mechanical property, and analyze and evaluate them. The result shows that there exists good correlation between the mechanical property and microstructure indices of sand after solidified by SH material. Anisotropy, equivalent diameter, aspect ratio, fill ratio and ratio are the five significant indices effecting on the mechanical property of sand with SH. It is shown that SH is an ideal polymeric soil consolidator in terms of microstructure.

Based on the analysis of main characters of weathered rockfill materials, the deformation of rockfill due to a change of the moisture contents can be forecasted using an extended Gudehus-Bauer hypoplastic model. The updated model takes into account a moisture sensitive granular hardness; and it can reflect the influence of density, stress state, rate of deformation and moisture content on the nonlinear, inelastic stress strain behavior of rockfills. Numerical simulation is carried out to simulate the evolution of deformation and stress of a core-wall type rockfill dam during the first water impounding. The results are reasonable.

The soil liquefaction caused by earthquake is one of the direct reasons for the foundation invalidation and the structure collapse. Based on in-situ tests, liquefaction estimation of silt with different origins in Tianjin area is studied. Then the dynamic properties and liquefaction mechanism of the silt were illuminated based on dynamic triaxial test. And a comparison between the existed earthquake liquefaction assessment methods was made. combined with the in-situ tests. It is suggested that the influence of silt content should be taken into account in the liquefaction assessment; and the value of pore water pressure is 60%-90% of confining pressure, the value of double amplitude strain is 4%, these values can be used as the indexes of liquefaction evalution.

The fusion efficiency of multi-sensor being theoretically proved to be better than that of any single sensor, analysis of groundwater macroscopic regime under a dam section was carried out by using a decision-making fusion method. As a result, following aspects can be identified.(1) The macroscopic regimes under dam section 9 had the tendency of increasing with time between 2003 and 2004, the close relationship with the reservoir water level; (2) The macroscopic regimes of section 9 kept close relationship with the reservoir water level from 2004 to 2007; (3) the anti-seepage performance of the curtain-grouting was to be weakened locally.

Preferred plane theory is used to analyze fault to lead water; and numerical simulation of seepage for rainfall infiltration is employed to explore distribution of seepage field of surrounding rock under extra condition. It is simulated that water volume is changed with the value of the coverage and permeability index of grouted surrounding rock to control leakage volume. The results show that grouted coverage not almost influenced on result while permeability index largely influenced on it; and it is found that fault has an accumulating water role. As if permeability index of grouting surrounding rock is controlled lower than 10-8 m/s, the effect of waterproofing can meet the need of construction and use of the tunnel. The conclusion can present a new idea to predict and cure flood of tunnel.

A field test area was selected for a marine soft soil treatment. Some factors such as settlement around tamping pit, settlement of sand pile, accumulation and dissipation of excess pore water pressure, and horizontal displacement of deep soil, are monitored during dynamic consolidation and replacement sand pile. Through analyzing the results, some useful conclusions are drawn as follows. First, eight times dynamic consolidation is reasonable for a replacement sand pile. Second, the excess pore water pressure will be effectively decreased after a short standing time; also most excess pore water pressure will dissipate completely after seven days of dynamic consolidation. Third, horizontal displacement of deep soil is taken place at 3?6.5 m depth.

The section of Y-shaped vibro-pile is complicated; its geometric characteristics has four independent variables and eight integral zones. It is difficult to achieve the expression of analytical solutions for additional stress coefficient at random point in the ground when the uniform tip load of the Y-shaped section acting in the ground; therefore, so far simple analytical solution hasn’t been solved yet. Using the integral function NIntegrate of Mathematica software and referencing the idea from Geddes stress solution, the numerical computational method for vertical additional stress coefficient at random point in the ground under the uniform tip load of Y-shaped vibro-pile was achieved; and it is accurate according to the verification. The influences of four independent variables, R, ?, s, ? of Y-shaped section on vertical additional stress coefficient due to uniform tip load and errors produced by Geddes stress solution were analysed. The difference and regular in vertical additional stress coefficient at section center in the ground under the uniform tip load of Y-shaped, triangular, rectangular, quadrate, circular, annular, H, and T-shaped section were analyzed along with the change of acreage and calculation deepness. The additional stress calculation method in which the section shape of Y-shaped vibro-pile is considered was used in settlement calculation of single pile. The calculation result is consistent with the data of static loading test.

To evaluate the rock classification, a useful rock sub-classification method is needed to eliminate the subjectivism and empiricism and to improve the precision of rock classification. Therefore taking into account of the attributes of the current indices, quantification theory is adopted to give the rocky surrounding rock quantitative evaluation. At first the index system was built on the basis of survey; then 500 data was gained from the more than 800 examples of 72 tunnels; thus the quantitative evaluation was achieved. Finally, through case studies, the judge method based on quantification theory was tested and a high precision and reliability is achieved. The research results show: The indices of rocky surrounding rock sub-classification during construction are rock hardness degree, rock mass integrity condition and ground water condition. Self-check coincidence rate of the discriminatory equation and values based on quantification theory exceed 85%. Quantification theory is a reliable method in rocky surrounding rock sub-classification during construction.

The thermal-hydraulic-mechanical (THM) coupling during the rock failure is of great significance for many engineering applications such as deep underground mining. A coupled THM model during the rock failure is proposed based on the conservation of mass and energy of solid and fluid when the damage is considered as a key factor that controls the THM coupling. The proposed THM model is firstly utilized to simulate the THM response of elastic medium; and it is validated by comparing the numerical results with the analytical solutions. Secondly, this THM model is employed to predict the coupled hydromechanical response of rock under different in-situ stress conditions. The numerical simulations indicate that, compared with the numerical results without hydromechanical coupling, the hydraulic pressure can not only facilitate the tensile damage and extend the range of tensile damage zone, but also restrain the occurrence of shear damage.

Based on Biot’s consolidation equation,the characteristics of the resistance of soil caused by horizontal vibration of elastic bearing pile embedded in saturated soil are analytically studied. Transforming the consolidation equation, by virtue of differential operator splitting and variable separation method, the horizontal dynamical characteristics of soil under steady state of pile-soil interaction are obtained. The comparisons with the equivalent single-phase solution and the single-phase solution are presented; and the condition of the solution that can be equivalent to the equivalent single-phase solution is indicated. A parametric study is conducted to determine the main features of pile-soil interaction in horizontal vibration, the effects of the permeability coefficient, the pile-soil modulus ratio and the pile slenderness on resistance of soil layer are studied.

Based on the theory of Westercard to calculate rigid pavement PCN value on the middle of a slab, a 3D finite element analysis model is established for rigid airport pavement in mountainous area considering the "subgrade-pavement-aircraft loading" interaction, the slab joint loading-transfer character and the differential settlement of embankment. Applying this method, fifteen groups of computational analysis models are established, and their feasibilities are verified by Westercard theory and Bisar software according to gathered ACN values of the domestic main civil aviation freighters. Studies show that differential settlement of subgrade is in linear relationship with maximum tensile stress, a control of 1‰ differential settlement for subgrade is reasonable in high-filled airport project, for pavement with designed strength above 5.0 MPa, 1.2‰ differential settlement for subgrade is permitted.

Pore-water in saturated soil gains both way drainages in radial directions by installing annular sand-layered drainages into the soft soil ground, and then the excess pore-water pressure can be dissipated along the two lateral surfaces of every annular soil layer. As addition of radial dissipation surface and reduction of dissipating distance, soft soil foundation can consolidate faster. Based on these ideas, the corresponding mathematical model of saturated soil consolidation and its analytical solution is presented; and then by a case study, the distribution and development of excess pore-water pressure, and consolidation characteristics of saturated soil are analyzed.

The genetic algorithm is used to search the parameters of least square support vector machine in order to avoid the blindness of manual searching and improve the generalization of the model. Based on the large amount of measured data of practical slope engineering, a genetic-least square support vector machine estimation model of slope stability is set up; and then it is applied to predict the stability factor of natural slope in Dingjiahe phosphorus mine. The agreement of the theoretical results with the actual situation of natural slope shows that the proposed model is effective and reliable.

The soil mass may appear partial sliding failure under shorter clear-space circumstance, which is based on survey and analysis of cantilever piles in incised slope. Three-dimensional soil arching effect and cutting-unloading stability analysis model of soil between adjacent piles is established based on the geotechnical strength theory and analysis results about initial stress and criterion of sliding failure. An incised slope of Xiang-Yu-Ⅱ Railway project is researched based on its theoretical calculation and field engineering observation. It is indicated that trailing line on sliding curved of soil between piles is usually located just inner side of soil arching effect; the soil appears sliding trend because of tensile-shear yield failure. It is also proved by practical engineering that soil nails accepted to bracing soil mass between piles can produce preferable reinforcement benefit. The soil nails should be drilled into area of soil arching, which is based on results of numerical simulation. Wedge-compact processes from soil grains bring some anchoring effect by a certain extent to soil nails.