A unified expression describing the nonlinear characteristics of strengths of various materials on the π plane and the meridian plane is used in the generalized nonlinear strength theory. Thus a brand new system of the nonlinear strength theory is formed. The nonlinear strength theory is developed from the single nonlinear strength theory which can be just suitable to a certain material to the generalized nonlinear strength theory which can be suitable to various materials. Therefore, the system of strength theory is completed. The generalized nonlinear strength theory includes a series of the single nonlinear strength theories which have already existed and might appear in the future, such as Mises's criterion, SMP criterion, etc.. The superiority of the system of the generalized nonlinear strength which is suitable to various of materials is verified by the strength tests on clay, rock and concrete.

The limitations of the present 3D rock stress measurements are briefly reviewed. A linear elastic model for the determination of the 3D rock stress tensor, based on a special method for stress relief on the local surfaces of a drilled borehole wall, is researched. The six stress tensor components can be calculated from this model. Numerical simulation on the whole stress relief process by side-wall core drilling using FEM was done. The response curves of the strains versus the depth of the annular slot advance are analyzed. Quantitative relationship between the relief depth and the diameter of the rock core to be unloaded is given when the stresses stored in it are completely relieved. Arrangements of strain rosettes attached to the borehole-wall are studied, being free from the influence zone of annular slot resulting from local side-wall core drilling, thus ensuring strain-gauging accuracy. The results obtained from numerical simulation are helpful for designing prototype test or model test and further developing the new stress measuring instrument. This stress measuring method discussed in this paper has a reliable theoretical basis that can not only solve the problem of core-breaking occurring in stress relief with overcoring technique but also overcome the premise of hydraulic fracturing method - one of the principal directions of rock stress tensor should be coincident with the borehole axis. There is also no need for a pilot hole during the stress measurements. It can be anticipated to be a new way and channel for rock stress measurements.

considering especially the influence of the thermal water diffusivity and the isothermal vapor diffusivity on the continuity of water and the energy balance, the author improved further the established control equations for analyzing coupled thermo-hydro- mechanical phenomena in saturated-unsaturated porous media. Using the experiment data of the buffer material and the 2D FEM code developed by the author, a numerical simulation for the coupled thermo-hydro-mechanical processes in near field of a conceptual nuclear waste repository in excavation and after closure is carried out; and the distributions and the changes of the displacements, plastic zones, principal stresses, pore pressures and temperatures in the surrounding rockmass are investigated. The computation results show that the excavation is the main reason for the displacements and redistributions of stress in surrounding rockmass of a cavern; and the coupled thermo-hydro-mechanical processes after the cavern closure also produce obvious influence on the displacements and stress states in the rockmass.

The typical area was chosen on the tidal flat of the Yellow River estuary where hard crust develop, simulating wave load test with a light compactor was carried out to study the repeat liquefaction and change law of crust layer within one meter through the monitoring of pore water pressure and in-situ soil strength measure. The results revealed that the dynamic response varies a lot along depth and the strength of silt increases after repeat liquefaction; the upper crust layer increases more obviously than the down. The undisturbed samples were taken before and after vibrating; and quantitative analyzing of SEM structure images is carried out on the samples of different depths. The results revealed that some indexes of microstructure change evidently; such as asymmetry coefficient descended, granularity direction strengthed, granulometric fractal dimensions improved and figure coefficient improved and ratio of pore will descended etc. The transformation varied a lot along depth with the range mainly concentrated above the upper site. The relation between the dynamic response character and their microstructure changes has been discussed; and the character and formation mechanism of hard crust under the control law of microstructure are grasped primarily on this base.

A general modified constitutive model of gradient and viscosity dependent is proposed based on kinematics description by Lagrange; and specified one can be gotten from an elastoplastic constitutive model in infinitesimal theory that is verified. Such a way to deal with the contribution by strain gradient and viscosity utilizes mostly the results of constitutive model research. And an analysis model of square intersection with unit sides, infinite in its length, and under infinitesimal description is adopted here to discuss the characteristic scale in perfect yielding material by parameters of the constitutive model under P wave inputting.

Laboratory triaxial tests were carried out in order to understand the stress-strain relationship and strength property of grassroots-reinforced soil (GRS). The change of shear strength indexes of GRS with the quantity of grassroots planted in the soil samples was investigated. The failure modes of reinforced and unreinforced soils were discussed; and also the frictional mechanism between the grassroots and soil in the shearing process was studied. The laboratory test results show that: (1) the strength and the capacity for resisting the deformation of grassroots-reinforced soil are better than those of unreinforced soil; (2) as to the shear strength indexes of GRS, the change of internal friction angle is small compare to that of unreinforced soil (its absolute value of relative rate of change is less than 11 %); but the cohesion is more larger than that of unreinforced soil (the maximal increased multiple is nearly 9); (3) in the certain number of grassroots layers, the value of deviator stress ,shear strength and cohesion first increase and then reduce with the increasing of grassroots quantity, i.e. there is an optimal reinforcement quantity existing in GRS in the given number of grassroots layers. The research results are of importance for understanding the mechanism of vegetation protection for slopes and determining the density of grass planting.

Connected with the engineering concrete example, through the collection, arrangement and analysis of related data, the site investigation and exploration of engineering geology, indoor and outdoor physico-mechanical tests, adopting the analytic means of mathematic statistics, unbalanced-thrust method and non-separation contact elastoplastic FEM together, the influencing factor sensitivity of debris landslide has been analyzed and researched. The results show as follows. First, through the sensitivity analysis of main factors to influence on the stability of debris landslide, its main influenced factors are internal friction angle of sliding surface, topographic grade, saturation-area ratio of slope-mass and cohesion of sliding surface by descending order of their sensitivity coefficients. Second, the integral stability coefficient of debris landslide with large topographic grade and the slip surface of small internal friction angle is more inferior. But steady rain and intensive rainfall can raise groundwater level, augment saturation-area ratio of slope-mass, lower the rock and soil shear strength of slip-surface, and increase downward sliding force, which will bring about the most disadvantage influence on the stability of a concrete debris landslide. Meanwhile, on reinforcing and treating the debris landslide, the measure raising equivalent angle of slip-surface internal friction and lowering topographic grade connected with lowering groundwater level must be taken the prior step, and may be thought over taking the next measure to increase the soil and rock cohesion of slip surface.

Retention criterion is an important part of filter criteria for geotextile, however, the prevalent design criteria is too strict for retention of soil particle and not enough for permeability criterion. Two different opening size distribution curves of geotextiles are introduced; and the probability that soil particles pass through nonwoven geotextile is calculated. Based on theoretical analysis, a probabilistic retention criterion is proposed. The new retention criterion restricts the probabilities that both coarse particle and fine particle pass through nonwoven geotextiles; and it can not only keep the stability of soil, but prevent the clogging of geotextile.

The expansive character of expansive soil slope is a very difficult problem. Now the modus operandi is that a press is set on soils; but the reasonable explanation in theory is not given; and the amount of the press is obtained only according to experience. An expansive model of expansive soils(ESEM) is put forward; and the method that the pressure is confirmed with back analysis according to displacement is given. And it is pointed out that the two ways are identical that the press and distortion are set on the slope soils by formula deduction. The analysis of rainfall is taken into account; and the finite element program is given based on the Drucker-Prager model. The back analysis is set up with 2-norm. The expansive parameter is calculated by the Newton’s iteration. The connection between the 2-norm and the expansive parameter is a curve that is single-valued continuous with a single concave point. At last, the expansive parameter and the expansive press formula of the expansive soil slope are given.

The contribution of matric suction to the stability of unsaturated soil slope should be properly evaluated in order to meet the demand of practice. Firstly, Bishop’s and Fredlund’s strength equations for unsaturated soil are discussed, respectively. Then the strength equations expressed in three-dimensional effective stress space are applied to the strength reduction finite element method and the treatments of the matric suction are discussed. Finally, the FEM codes are implemented and a case of unsaturated soil slope stability is analyzed.

Through the analytical solutions, the effects of saturated and unsaturated sediment on the dynamic pressures in the overlying ideal fluid due to P wave incidence from underlying elastic half-space are investigated. The sediment is modeled respectively as elastic solid, viscoelastic solid, ideal fluid and viscous fluid. The results obtained are compared with the case in which sediment was viewed as a two-phase poroelastic media. It is concluded that the two-phase poroelastic media can be simplified approximately as a viscoelastic or even as linear elastic solid when its permeability is relatively small (k≤10-3m/s). The findings are useful for construction a sediment model in dynamic analysis of dam-reservoir-sediment-foundation system to enhance the efficiency of the numerical procedures.

Based on the variational principle, the total potential energy of a general group of vertically loaded barrettes is established. By using the double Gauss numerical integration method, it is expanded to a simple equation of matrix form, in which a finite series is used to denote the vertical displacement of barrette shaft, Mindlin’s point-to-point displacement solution is applied to describe the force-displacement relationship of ground soils, and allowance is made for the non-uniform distributions of both the side shear stresses along the perimeter of the barrette shaft and the normal stresses at the barrette base. In light of the principle of minimum potential energy, an explicit solution is obtained for the load-settlement relationship of barrette groups. The proposed solution is verified from the comparisons of the calculated results made with an approximate three-dimensional method. Its merits in higher computational velocity and greatly reduced computer storage memory are also illustrated.

Through electrical resistivity experiments and geotechnical experiments, the characteristics of electrical resistivity of thick soft soil layer and the correlativity between electrical resistivity and engineering mechanical parameters in the foundation of Suzhou-Nantong Yangtze River Bridge in China’s Jiangsu Province, were studied. It was found that, firstly, in CZK30 bore, from clay→powdery sand→thin sand→medium and coarse sand, the electrical resistivity of soil sample increased gradually, the electrical resistivity decreased with the increase of water content, void ratio and saturation, and increased with the increase of the vertical and horizontal infiltration coefficient, compression modulus and standard penetration test (STP); secondly, in CZK30 bore, electrical resistivity of clay soil decreased with the increase of the water content, void ratio, saturation, compression coefficient, liquid coefficient, and increased with the increase of compression modulus and cohesion; thirdly, through linear and polynomial fit, the mathematic expressions between electrical resistivity and engineering mechanical parameters of soil were offered, and the correlativity coefficients were high (larger than 0.88 mostly). The following conclusions can be drawn that there exist affinity between electrical resistivity and other physical and mechanical parameters.

A new unified axisymmetric characteristics line theory for weight materials is proposed based on the twin shear failure criterion; and pressures acting on the shaft wall are researched; and a new calculating method is given out with the new axisymmetric characteristics line theory. Example results show that the relationship between the pressures and the shaft depth is nonlinear. The parameter b in the twin shear unified strength criterion has significant effect on pressures. The larger the b is, the less the pressures are when shaft is at the same depth.

The soil nailing walls is a kind of retaining structure to stabilize foundation pit and slope. Composite soil nailing walls is formed by combining soil nailing with prestressed anchor bar. According to the interactive mechanism of soil nailing, prestressed anchor bar and soil mass, a jointly interactive model is proposed to simulate supporting and anchoring effect of the composite soil nailing walls. The mechanical model is applied to a deep & large foundation pit which was designed by authors; and the supporting design scheme for the foundation pit has been effectively optimized. Stability of the foundation pit and safety of surrounding environment under excavation state have also been ensured. The supporting for foundation pit has achieved complete success.

As a rule, to confirm blasting vibration attenuation rule, coefficients of the Sadov’s vibration formula can be regressed with three variables, namely, maximum vibration velocity, maximum charge amount per delay interval, distance between center of blasting area and measurement place. To confirm blasting vibration attenuation rule accurately, coefficients of the Sadovski vibration formula can be gained by use of the unary linear regression theory for per delay consecutive firing, with maximum velocity at different times, corresponding charge amount per delay interval, distance between measurement stationing and hole. A fine analysis method for blasting vibration testing is put forward.

2D seismic response of landfills is explored in detail, in order to investigate stability of landfills at different intensity of earthquake shaking, as well as to evaluate the relative importance of different factors influencing the seismic response of landfills. The results indicate that the stability of landfill cover depends primarily on wastes properties, landfill heights, spectral characteristics of input motions, and site conditions; however, for base sliding case, the stability varies significantly due to the peak acceleration, period of input motions, and the basic period of landfill.

Based on centrifuge experiment of nature foundation and mixing pile composite foundation, foundation settlement varying with time, effect of mixing pile on foundation settlement control, stresses of different depths of pile and soil, and vertical strains along the piles varying with time are discussed. The result is useful for selection of foundation improvement methods for Beijing to Shanghai high speed railway and for theoretical calculation of composite foundation settlement.

A new formula to estimate rock specimen damage parameter and its strain is established by means of ultrasonic velocity test under uniaxial compression. According to the formula ultrasonic velocity characterization with different homogeneity indices under uniaxial compression is analyzed. As the homogeneity index increases, the ultrasonic velocity decline rate increases. This conclusion coincides with numerical test of rock acoustic emission(AE). Regression analysis between rock ultrasonic velocity and strain is carried out based on the test results of rock under uniaxial compression. From the above point of view, the regression equation between rock ultrasonic velocity and strain which is of comparatively high accuracy, is obtained. And it reveals that the established formula is reliable. Kaiser effect of AE will appears when ultrasonic velocity declines obviously according to the discussion of the relationship between ultrasonic velocity and AE during the deformation of rock under uniaxial compression. So the result is helpful to research in-situ stress measurement using Kaiser effect of AE under uniaxial compression.

In order to research the frost heaving resistance and deformation characters of pile foundations for bridges and buildings in permafrost region, based on the test projects of Qinghai-Tibet railway, the uplift tests of the cast-in-site bored pedestal pile and column bored pile have been studied in high-temperature fine-grained permafrost of Qinghai-Tibet plateau. The test results of uplift resistance and deformation are gained for the two different types of piles under the same geological condition and temperature. In addition, according to the ground temperature data, the back frost time of pile-soil system and the characters of ground temperature change are given. The investigation could be used as references in the design and construction of frost pulling-resistant pile under the similar conditions.

Based on a brief introduction of the self-consistent method and the theory of soft foundation dealt with blasting method, this paper calculates some resilient modulus, which are largely in accordance with the data in the experiments. The results justify the practicability of calculating the resilient modulus of the soft foundation with self-consistent method.

Aiming at subsistent limitation in diversified displacement back analysis methods, an approach based on neural network and genetic algorithm for displacements back analysis of deep foundation pit for metro is proposed. This approach utilizes nonlinearity of neural network and whole random search capability of genetic algorithm. It can search the best appropriate weight and framework of neural network by using whole searching characteristic of genetic algorithm, which formerly depends on gradient information to adjust weight of network. The proposed approach has been used to carry out inverse calculation for soil mechanical parameters of deep foundation pit for metro. A case is conducted using the software developed in the paper. The result shows: considering measured deformation value as input data and taking soil dynam parameter as output data of neural network, the approach can rapidly get a stable and accurate solution within a relatively large solution space; and the approach is superior to current back analysis approaches.

According to the further developing platform, the Duncan-Chang constitutive model is developed in FLAC3D with VC++ environment. A series of numerical simulations of triaxial tests are performed to verify the correctness of the compiled model. The provided basic procedures and programming essentials of the constitutive model redefining in FLAC3D offer a reference for other developers. Because of the characteristic of the development environment, a user-defined model has the same execution efficiency with the in-built model in FLAC3D.

The extreme conditions of yield condition and yield function are discussed; and a velocity equation is established under the condition that no flow rule has been required. The equilibrium equation, extreme conditions of yield condition and yield function, and velocity equation are the fundamental equations for limit analysis of soil mass, which constitute a complete limit equilibrium problem of the boundary conditions for loading and velocity, including the coexistence of boundary conditions for loading and velocity. The upper and lower bound theorem of slope stabilization is rigorously proved; and a generalized method of limit equilibrium has been established to solve the problem of limit equilibrium. The calculated result of homogeneous soil indicates that the generalized method of limit equilibrium for a circular slip surface is basically identical with the upper bound solution for a logarithmic spiral surface.

The parameters of transversely isotropic soil are obtained from the conventional triaxial compression tests. In order to study the effect of transversely isotropic soil parameters on settlements of buildings, nine types of transversely isotropic soils taken from different countries are used. As a typical example, the interaction analysis of cross-wall structure and box foundation on transversely isotropic soil has been made and compared with the results on isotropic soil. In this example the structure is analyzed by using the double extended substructure (finite element) method and the transversely isotropic soil by the finite layer (element) method. The results show that the effect of transversely isotropic soil on settlement is somewhat different, especially for the soil parameters determined by the consolidated-undrained tests. It is expected that these conclusions are useful to the foundation designers.

Degradation of stiffness and strength will occur in soft clay under cyclic loading because of the generation of pore pressure. Unfortunately, previous work rarely incorporated the effect of initial deviator stress on cyclic degradation behavior. In this paper, the degradation of stiffness characteristics of normally consolidated soft clay subjected to undrained cyclic triaxial loading are investigated at different numbers of cycles, different cyclic stress levels and different initial deviator stresses. The influence of these three factors on the shear stiffness is investigated by analyzing the secant shear modulus in each unload-reload loop. It’s observed that the stiffness reduced with progressive number of cycles. On the other hand, higher cyclic stress level and initial deviator stress accelerate the degradation of stiffness. A linear relationship is obtained if secant shear modulus is plotted against numbers of cycles on a semi-log scale. This relationship has been synthesized in the form of an empirical equation. The failure stiffness ration for Xiaoshan soft clay is obtained from the equation.

Through doing one-dimensional equal amplitude circulating compression test of sand, the compression and resilience deformations of the aquifer caused by the groundwater level rising or falling are simulated; and the effect of the circulating number on the vertical deformation and porosity is analyzed; the reduction rate of porosity is proposed; the influence of groundwater level rising or falling upon the groundwater reservoir storage is evaluated by the reduction rate of porosity; a conclusion is obtained that rising or falling of groundwater level will can not affect using of groundwater reservoir.

Pile-net composite foundation has been emerged as an effective alternative successfully adopted worldwide to solve many geotechnical problems. It combines the advantages of the horizontal reinforcement layer and the vertical reinforcement. Related to pile-net-soil cooperative function, pile-net composite foundation is so complicated that designed mainly by experiences, which limits its application. It is very difficult for pile-net composite foundation mechanism to be researched by theoretical analysis. General model test and soil centrifuge modeling test can only solve some problems qualitatively; and some important technical questions need in-situ solution. With in-situ test of a certain high-speed railway trial embankment, pile-net composite foundation has been careful studied in settlement and lateral displacement and contact pressure and the stress and strain of geogrid aspects. The change process in pile-soil stress ratio and the bearing properties of geogrid and settlement have been analyzed. Systematic researches on soft embankment settlement laws, the pile-net composite foundation bearing mechanism and stress transmission mechanism have been performed. How net mat made by geogrid and mat impacts settlement control and how it is designed have been discussed.

A testing apparatus is introduced which can carry out both uniaxial compression tests and uniaxial tension tests on a same rock. This apparatus changes the situation of analyzing the test results from different rock samples under uniaxial compression and uniaxial tension respectively, which will lead to a wrong conclusion. And it also provides the possibility for studying the transitional characteristic of rock from being compressed to being sketched or from being sketched to being compressed. Furthermore, the deformation behavior of purple sandstone in Dayao Copper Mine is studied. The research indicates that the compressive elastic modulus of purple sandstone equals to the tensile elastic modulus, but the changes of Poisson's ratio in compression and that in tension are complicated. The tests also prove that rock compression and tension are not quite different courses. The deformation curve of unloading in compression joins continuously together with that of loading in tension.

Residual soil filled embankment failures have been the major part of landslide. The landslide event occurred at the filled embankment adjacent to the bridge abutment of Tudiyang Bridge at Nanping Section of Beijing-Fuzhou Expressway has been analyzed; and some factors affected on the residual soil filled embankment failure have been analyzed. The rainfall infiltration, as the most important factor, affected on this landslide event. Based on the parametric evaluation of the residual soil filled embankment failure, such mechanism analysis of filled embankment stability has been given. And the landslide were also caused by other triggering factors including the compacting factor of residual filled soil, the residual soil characteristics and the slaking deformation. The results offer engineering treatments of designing the high residual soil filled embankment and controlling the quality of construction.

Based on the suppositon of the process of pile driving of Precast Pressure Hollow Pile as the expansion process of cylindrical cavity expansion with initialized aperture and terminal aperture which are respectively equal to inner diameter and external diameter, the expressions of radius of plastical zone, soil displacement are deduced using cylindrical cavity expansion theory; the discussion of plugging effect which appear in the tubular pile costruction offenly is also made. The soil displacements are figured out provoked in the process of precast tubular pile costruction in an electric power plant extend program using the expressions; and the conclusion is come out by checking with data obtained from field monitoring that these expressions are appropriate and could be utilized to forcast the effect of precast tubular pile driving.

The reducing of additional stress due to groundwater submergence is studied; and the influence of the variation of additional stress on final settlement is analyzed. The consolidation settlement formulas taking into consideration submergence of small-strain and large-strain are derived. The results from several numerical examples are analyzed and compared. It is shown that the influence of submerge on consolidation settlement of ground increases with load, soil compressibility and thickness of soil, The calculating value of consolidation settlement using large-strain consolidation theory is rather accord with actual examples.

A three-dimension elastoplastic model had been developed to study the space effect of the soil-nailing excavation protection. The positive corner effect, negative corner effect and layered excavation were emphatically analyzed. The researches showed that: the negative corner of excavation could reduce the displacement of excavation and the force of soil-nail; and its influence was once more than the depth of the excavation; meanwhile, the displacement of the excavation and the force of soil-nailing were much larger in the positive corner; and its influence is near to 3 times of the depth of the excavation; the space effect of soil-nailing pit could be used plenarily by layered excavation; its influence was near to the depth of the excavation. It was proved that three-dimension numeric analysis of the soil-nail structure was very useable.

The formula for deep-mixing pile composite foundation on the code is bad with correlation of the geologic strata parameter (such as soil modulus on the end of pile foundation, pile foundation size, subsidiary stress etc). So, it is more difficult to accurately calculate modulus of grid composite foundation. Based on the interaction of grid and soil, a formula about compressive modulus of grid composite foundation is deduced. By comparing the field static load test results of engineering of high-rise building, it is proved that the formula is reasonable for calculating for grid foundation for high-rise buildings.

The improved genetic algorithm is proposed to identify the defects of pile detected by low-strain integrity testing. Considering the premature phases and slow rate of convergence in evening of genetic algorithms, adaptive niche technology and adaptive probabilities of crossover and mutation are both introduced into the classical simple genetic algorithm, with one dimension theory of stress wave and finite difference method to identify the defects of pile. The study shows that this method is suitable for the automatic identification of defects of pile detected by low-strain integrity testing. It can also avoid premature phases and slow rate of convergence in evening that often happen in simple genetic algorithms. Finally, a good performance is achieved.

A new stochastic search optimization algorithm, artificial fish swarm algorithm (AFSA ), is presented firstly; and according to the ergodicity and stochasticity of chaos, we combined artificial fish swarm algorithm and chaos to form a new fusion optimization algorithm, chaos artificial fish swarm algorithm(CAFSA). Then CAFSA is applied to inverse the parameters of gravity dam. Results of computation example show that CAFSA has the advantages of rapid convergence rate, high optimization efficiency and high inversion accuracy; so a new way for solving the problem of optimization and identification is provided.

By using the high pressure gas gun as power to accelerate plane plate, and the amphibole samples, which were subjected to the plane plate impacted with different impulses, have been recovered. Then these recovered amphibole samples have been studied by some micro-mine research techniques such as SEM, XRD and RAM. In this research, the stress intensity in the beginning phase of crack appearing and the extending shape of cracks have been confirmed. Based on the analyses of micro-examination for these recovered samples, the formation principle of crack is expounded and proved there is phase transition in the amphibole. These experimental results can provide a kind of new theoretic basis for the further studying of the explosion in mine exploitation, architecture engineering, etc.

The cracks of fissured soils are important factors that affect the soil engineering properties. To study the process of crack evolution under changing environmental conditions, an experimental device that can precisely control the humidity is designed; and the process of crack formation, propagation and extending reappears by using this device. The experimental results have been theoretically analyzed; and the disciplinarians of crack emergence, propagation and extending in the experiment have been educed. The research results could do help to the comprehension of the physical changing process of soil cracks and provide considerations to deal with the engineering problems.

Based on the slip-line in plastic mechanics, equilibrium differential equations of a foundation in limit equilibrium state under a strip footing are deduced. using the finite-difference method, the finite difference formula in limit equilibrium state is given. Combining with the boundary conditions, a program for computing the bearing capacity is written that can compute the slip-line field and the corresponding bearing capacity considering the depth of embedment, the unit weight, the internal frictional angle and the roughness of the foundation at the same time. The calculating results of the bearing capacity factor Nγ are shown with the change of the internal frictional angle. The influences of the depth of embedment, the unit weight, the internal frictional angle and the roughness of the foundation on the shape of slip lines and the bearing capacity, are generally discussed; and some valuable conclusions are drawn.

Settlement monitoring is an important aspect of geotechnical engineering. A lot of settlement monitoring instruments which work in normal temperature circumstance, will confront complex questions when they face low temperature circumstance; and their performance will also play down greatly. So we developed a drill monitoring instrument for frozen soil settlement in consideration of the particularity in low temperature circumstance. The instrument utilized advanced technology of numerical code monitoring and optical fibre transmission. Principle and practice of the equipment have been detailedly introduced. We carried out the embankment filling grading and reconstructing local experiment, inbuilt the frozen soil settlement drill monitoring instrument to monitor the settlement of the frozen soil. Result shows the settlement drill monitoring instrument has high quality and reliability and is worthy of popularization and application for the strongpoint of direct-viewing and convenient manipulation.

Geomechanical parameters have structural and stochastic properties on spatial variability, which causes the uncertainty of geomechanical parameters. Geostatistics is used as the theoretical foundation for analyzing the spatial variability of geomechanical parameters; and geomechanical parameters distributing in region of interest are considered as zonal variables. Variogram function can not only describe the integral spatial structural variety, but also describe the local stochastic variety. Therefore, theoretical model of variogram function is employed as the mathematical model for depicting the spatial variability law of geomechanical parameters. The ensemble Kalman filter method is introduced to estimate the spatial variability of geomechanical parameters using the observation data with temporal and spatial variation. Demonstrated by numerical example, the EnKF can effectively incorporate the observation data and successfully provide the spatial variability estimation of geomechanical parameters.

The Yuanjiawan Landslide, located on the section of k15+000-k15+500 of the Lanzhou-Lintao expressway, is a bedding landslide triggered by cutting the high and steep slope. The landslide has been slided during excavation and exertion of the highway. It is a large-scale and harmful landslide with the characteristics of repetition and succession due to its geological condition, rock mass structure and the design of the slope of the expressway. Based on geological condition, project feature and the characteristics and history of sliding, the causes of occurrence and the mechanism and process of evolution of the landslide are comprehensively analysed by using engineering geology, physical model test and FLAC3D numerical simulation.

CO2 geological storage is one of the effective means to reduce net CO2 emissions. CO2 geological storage has a history for more than ten years in developed countries. Currently, research of this aspect is started just now in China; so it is very necessary to carry out an investigation on the status quo of CO2 geological storage technology in China. CO2 geological storage process involves three factors: capture of the CO2 from the power plant or industrial process; transmission of the CO2 to the storage site followed by injection into the geological reservoir. Many of the technologies required for large-scale geological storage of CO2 already exist in the existing industry and the oil and gas industry. Now a preliminary investigation on the status quo of technologies of CO2 capture, CO2 transportation and CO2 injection and storage in the existing industry and the oil and gas industry in China is carried out and compared it with foreign countries; the findings of investigation show that there is a certain disparity of CO2 geological storage technology between China and foreign countries; however, there is a certain technology base of CO2 geological storage technology in China, especially, there is a certain practical experience in the aspect of CO2 recycling and injection.

Anchor effects, pullout strength and corresponding main influential factors are studied under different geological conditions. Based on anchor bearing arch theory, a calculation method of system anchors bearing capacity is proposed and applied to analyzing the bearing capacity of different support types under different geological environments. Cost-effectiveness ratio is also compared. Result from the analysis is that: system anchors play an important effect in the surrounding rock mass; and the cost-effectiveness ratio decreases greatly as the geological condition deteriorates. Combined with several engineerings design and construction, conclusions can be drawn that few and long grouted anchors should be used instead of frequent system anchors in soft rock mass for better stabilizing the early supports.

It is the key to design reasonably how to decide the size and distribution of loads on the underground structure in “action-reaction” model. For shallow tunnel in soft stratum, the vertical earth pressure is the whole weight above tunnel. But for deep-seated tunnel, it is decided by proposed formula in code, Terzaghi theory or M. M. Promojiyfakonov theory. It is a significant task to further study because of the question for choosing these formulas. Based on the size, the depth and the stratum of the lines No 4, No 5 and No 10 of Beijing metro tunnel, safety factors of standard sections are analyzed using ordinary overburden pressure theory. The calculation method of vertical earth pressure is presented. Not only it is fit for Beijing metro tunnel, but can be as reference for similar metro tunnel and city underground engineering.

All factors considered in the rock mass classification and processing methods are summarized systematically. Although there is no legalized criteria about the rock mass classification right now, people have reached the agreement that the rock mass classification should be based on the strength of rock, the integrity of rock mass, the conditions of groundwater, the conditions of ground stress, etc. Meanwhile, the rock mass classification of the national criteria belongs to the trend of joining the international track.