Based on lumped mass model of soil-structure dynamic interaction system proposed by Penzien, a simplified method of soil-underground structure dynamic interaction system is constructed with the consideration of the shear stiffness and damping characteristic of equivalent soil layers. Shifang Bajiao acceleration record, Songpan acceleration record of Wenchuan earthquake, China in 2008 and a Taft earthquake acceleration record with different frequency spectrum characteristics are selected as bedrock ground motions; then the simplified method and 2D finite element method are employed to analyse seismic responses of soil-subway station structure system. The results indicate that the peak value of acceleration response of subway station structure of the simplified method is more than those of 2D finite element method, and the difference degree is related to the bedrock ground motion characteristics. With the peak value of bedrock ground motion increasing, the difference degree of the results obtained by two methodes is increasing; but the general law is consistent. The simplified method is a good analysis method to analyse the effect of soil-underground structure dynamic interaction; and it can serve as a auxiliary method for aseismic design of underground structure.

The uniaxial different frequency cyclic loadings and unloading tests on biotite granite comes from the Changjiang of Hainan nuclear power first-stage construction major factory district are done on the RMT-150B multi-function automatic rigid rock servo material testing machine. The law between cyclic frequency and dynamic stress- dynamic strain hysteretic curve, dynamic elastic modulus and damping ratio are researched. Then the microtest (SEM) is carried out to study its fractography morphology and microstructure characteristics of failure surface under different frequency cyclic loadings. The results show that the curves of strain and stress for loading and unloading are not superposition under cyclic loading, but hysteretic loops. When cyclic frequency changes between 0.01 Hz and 1.0 Hz, the granite hysteretic loop area, dynamic elastic modulus and damping ratio are increased with frequency increaseing. Based on the testing analysis of microscopic digital image, there are more total number, larger area and fractal dimension of micro-cracks on rock fracture under higher frequency cyclic loading. Mesomechanical damgee mechanism of rock failure under different frequency cyclic loadings is given. The research result offers great reference value to seismic response analysis and site safety evaluation of the nuclear power factory in Changjiang.

Based on the analysis of the mechanical features and fundamental theory of geological materials, Shen et al.(2002 and 2003) proposed the framework of breakage mechanics for geomaterials and the concept of binary-medium model(BMM). Recently, we have carried out much research, including tests, theory and numerical simulation, on the structured geomaterials on the basis of the binary-medium model concept. Plane tests of the samples assembled by geo-structural blocks were conducted to investigate the breakage mechanism of structured geomaterials. It was experimentally found that the structural blocks will gradually break and transform to the weakening bands; and both of them will bear the loading together during the loading, testifying mechanical idealization of breakage mechanics for structured geomaterials. A new method of preparing for structured soils was explored; and the mechanical and strength characteristics of artificially prepared structured soils were studied under different stress paths. The binary-medium model for geomaterials was extended and verified that it could be used to simulate the brittleness change of geomaterials and experimental results of structured soils and sandstones under triaxial stress conditions well. Based on the concept of the binary-medium model for geomaterials, a mesoscopic numerical method which can simulate the breakage processes of geomaterials was proposed; and a strength criterion for structured soils was put forward finally.

Using a new apparatus which was fabricated by ourself, some research works on the stability of slope model under different boundary conditions effect were finished. Based on some associated results, the relationship between landslide start degree and boundary condition effect can be got. From the relationship, it can see clearly that the degree will decrease as the slope’s thickness increases and it will keep at a constant degree value when the thickness is relative big; namely, the influence induced by boundary condition effect can be ignored at that time. At the same time, one theoretical method was involved to quantify and confirm this relationship. In addition, the comparison between boundary condition effect and porosity indicates that the porosity is a more sensitive factor as to the range in variation of landslide start degree than the boundary condition effect. Based on these results, we can take some modification work for this experimental apparatus and get an optimization resolution for latter tests.

The stress state and deformation of surrounding rock of deep-seated tunnels are very important to design of underground engineering. With consideration of the stress concentration and relaxation induced by the nonuniformities, a series of equations for the surrounding rock follows in the deforming process, including the relationship between excess stress and nonuniformity size and unloading duration, is established to deduce the analytic expression of deformation of surrounding rock. The whole deforming process is divided into two stages: the unloading stage and the stress relaxation stage. And the approximate analytic expressions of stress and deformation are solved by successive approximation method. The solutions take the stress concentration and time effect of unloading into account; and they reflect the influence of nonuniformity and unloading duration on the stress and deformation of surrounding rock. Analytical results show that the local excess tensile stress concentrations appears in surrounding rocks in and after the unloading process; and the deformation have a additional increase after unloading.

Geo-reforcement foundation is a new type of pile foundation that is firstly developed and utilized in Japan. Compared with normal straight pile, this type of foundation can not only save materials and cut cost, but also can increase the bearing capacity greatly; so its application prospect is wide. Through model tests, the influences of anchor space, anchor length and anchor number on the bearing capacity of geo-reforcement foundation are analyzed; and some preliminary studies of the bearing mechanism of geo-reforcement foundation are made. The conclusions are as follows: the bearing behavior of geo-reforcement foundation is different from that of straight pile; the anchor can not only increase the side resistance of geo-reforcement foundation, but also increase the tip resistance to some extent. When the load on the pile top is the same, the displacement of geo-reforcement foundation is much less than that of normal straight pile; compared with large diameter pile with the same volumn, geo-reforcement foundation can greatly improve the foundation bearing capacity, reduce the settlement; when the anchor space is in some range, it effects the ultimate bearing capacity smally, while functions greatly on the ultimate side resistance; existing a critical anchor length, when anchor length is the critical length, its utilization effect is best; the ultimate bearing capacity of geo-reforcement foundation varies when the anchor number is different; and we can gain a satisfying bearing capacity increment by increase the anchor number appropriately.

Based on the developed 3D authentic nonlinear effective stress dynamic analysis method of high earth-rock dam, the analysis method to evaluate the maximum aseismic capability of high earth core rockfill dam is proposed considering the characteristics of high earth–rock dam on deep riverbed alluviums located in the strong earthquake area. The maximum aseismic capability is studied and evaluated by focusing the emphasis on the stability, deformation and safety of the impervious core and impervious wall in riverbed alluviums which should be the decisive factors on the aseismic safety of high earth–rock dam on deep riverbed alluviums. The proposed method has been successfully applied to the maximum aseismic capability evaluation of Changheba high earth core rock-fill dam with several evaluation standards discussed. Based on the comprehensive study results including dam slope dynamic stability, earthquake-induced permanent deformation, liquefaction potential, element aseismic safety and aseismic safety of the impervious core and impervious wall, the maximum aseismic capability of Changheba high earth core rockfill dam is evaluated as about 0.50-0.55 g.

A totally new sheet-pile bulkhead with load-relief platform supported by vertical cast-in-situ piles is proposed to meet the construction of deep water berth in the new port where there are soft clay strata in ground. It is necessary to make an investigation by physical modeling into the behavior of this new type of sheet-pile bulkhead, especially into the contribution of load-relief platform supported by vertical cast-in-situ piles. Three large geotechnical centrifuge model tests were conducted to verify the proposed design of such new port structure to be built. The contribution of load-relief platform is also displayed by comparison of behaviors of sheet-pile bulkhead of two schemes, one with load-relief platform and another without it. Also the centrifuge modeling technique for sheet-pile bulkhead is introduced including model design, model preparation, model instrumentation and testing procedure, etc.

The internal mesomechanical constitution and structure of rock determine the stress and strain distributions; and hence control the failure mechanism and process of the rock under to loading. The digital image processing (DIP), adopted as a tool of precise measurement and digital representation for the spatial distribution of different components of geomaterials, has been widely applied to the internal structural quantitative analysis of rock at the meso-level. The digital image processing is currently taken as an innovative method for investigating the rock mesomechanical behavior. At present the relevant researches mainly focus on: non- contact measurement of rock fracture aperture, digital representation of rock heterogeneity, analysis of rock mesomechanical behavior, establishing correspondence of rock’s numerical characteristic with its physico-mechanical properties in order to achieve fluid and solid coupling mechanisms, establishing numerical simulations for rock mesomechanics. Based on a comprehensive review of related researches documented in literatures, this paper investigates and discusses in detail the characteristic and development of the digital image processing in quantitative analysis of various rock mesomechanical problems; and analyses the advantages and shortcomings of these research methods. The digital image processing has a great potential to be developed and utilized in rock engineering due to its proved efficacy in measuring geomaterial spatial distributions.

The Hansbo’s formula for the non-Darcy flow was introduced to modify Terzaghi’s one-dimensional consolidation equation considering that the compressibility of soil in the over-consolidated state is usually less than that in the normally consolidated state. The cases under the cyclic loading with low-frequency were taken into account by using the presented equation; and the numerical solution was performed using the finite volume method. Then the effects of the parameters of non-Darcy flow, the period of loading and the compressibility of soil in the over-consolidated state on the consolidation process were investigated. The results indicate that, under the cyclic square loading, both degrees of consolidation in terms of settlement and pore water pressure are shown as vibratory increase with time; and the amplitude of degree of consolidation in terms of pore water pressure is greater than that in terms of settlement. In addition, it is found that the settling velocity of foundation is delayed by the non-Darcy flow, and decreased as the period of loading shortened or the compressibility of soil increased in the over-consolidated state.

Rheology is basic mechanical property of rock and soil media. For the slope,rheological property of rock and soil media is one of the important reasons for the large deformation and loss of stability. The time-dependent behavior of rock mass is one of the important factors, that influence the deformation and long-term stability of the slope. Based on coupling of long-term prestress loss of anchor tie and slope creep, a new improved Burgers model is built; and the theoretical function of long-term prestress variation is put forward. By comparison with the experiment result, which gets the viscoelastic rheological parameters of suggested model. The comparison between the rheological model and experimental result shows that the generalized Burgers model is right and reasonable.

The propagation and reflection rule of shock wave in vertical shaft under interal explosion is analyzed systematically. Based on the elastic theory, the dynamic equation is built; and the calculation formula of dynamic response of vertical shaft is derived; and the maximal radial displacement and internal force distribution of side wall of vertical shaft are obtained. The calculation results show that the location of the maximal radial displacement of vertical shaft is in the middle of shaft, which is related with the height of explosion; and as the increasing of the explosion height, the location of maximal radial displacement moves to the shaft mouth; but its amplitude become less.

On the basis of axisymmetric equal strain equation of sand drain foundation,the axisymmetric analytical solution of the pore water pressure and consolidation degree under vacuum preloading were derived in this paper. The effect of vacuum loading speed was considered by the function, which was used to simulate the initial condition of surface pore water pressure,and resolved the contradiction of pore water pressure boundary condition and initial condition at the surface.Well resistance and smear were also considered in the analytical solution.With the other answers as well as the numerical solution,the analytical solution has been verified through an example calculation, and ti can be further applied in practical engineering design.

In order to find how the mesostructure character of rock influences the crack propagation, the heterogeneity degree, grain size in limestone, marble and granite gneiss samples were examined respectively by means of scanning electronic microscope(SEM) and polarizing microscope. Then, the three-point bending samples with an pre-existing mode I crack were impacted by drop-weight and the cracking modes of above-mentioned three types of rocks were captured by high speed photography. By contrast, there is largest microcracking area ahead the crack tip in the granite gneiss samples with the highest heterogeneity, so is the lowest dimensionless ultimate crack velocity during the dynamic fracture process. On the contrary, since the lowest heterogeneity of the limestone samples, the smallest microcracking zone and highest dimensionless crack velocity were obtained. In this regard, there should be an internal characteristic length scale that domains the ultimate crack speed in rocks: the larger length scale is, the lower crack velocity limit would be.

For studying dissolution mechanism conditions of carbonate rocks driven by hydrodynamic pressure in different storage periods, the carbonate rocks in a hydropower station at Wujiang River was selected as a research object; and the simulation experiments by using self-developed pressure corrosion equipment in open system was proceeded which showed that with the hydrodynamic pressure rising (from 0 to 2.0 MPa), the dissolution rate of carbonate rocks are increased. The curve of dissolution rate is obviously changed. During the dissolution of the carbonate rocks, with the water pressure increasing, the chemical dissolution and the mechanism damage obviously as changing as the hydrodynamic increasing, the ratio tends to 1:1. The results show that there is a coupling relationship. Microcosmic research based on scanning electron microscope and mercury injection test, the dissolution not only affects on the surface of the rock produce secondary pore and secondary mineral, but also influences the inner pore structure, decreases the permeability and connection among the structural planes of rocks.

Variation of pore water pressure is the microstructure foundation of saturated clay’s macro-deformation. Taking the Yangguang Xincheng project for example, pore water pressure was monitoring during the construction of long spiral CFG pile on site; and then summarized the variation of pore water pressure. According to the law of pore water pressure changes, CFG pile construction is divided to several stages. The results show that the variation of pore water pressure conflicts with conventional point of shear liquefaction; pump and fleeing bore influence pore water pressure obviously; and then the reasons for this phenomenon are given. The maximum and minimum values of pore water pressures have has accumulation effect, which performances non-symmetry along a pile construction, but amplitude of pore pressure change assumes approximate symmetry. Based on the amplitude of pore water pressure, the sphere of CFG pile construction influence is determined; and its value is relatively consistent with the cavity expansion theory’s result.

Dispersive clay has the very low erosion resistance capacity so as to cause serious threatening to the engineering safety such as the hydraulic engineering and road engineering. It is one of the problematic soils which have been concerned in the geotechnical engineering field. As dispersive clay was found later and engineering cases were less, those studies of dispersive clay are still not deep enough. This paper has analyzed and summarized the current researches from some sides, such as the discovery history and the engineering hazards, the geological condition and the distribution rules, the identification methods, the engineering properties, the dispersive mechanism and the microstructure and the application. Some issues in the researches and the direction of researches are pointed out.

Because of the upper soil mass relative moving to the lower soil mass beside the ground fissure, there is the complicated action mechanism between lining structure and wall rock of soil with fissures. For investigating the engineering behaviors of Xi’an metro tunnel crossing ground fissures widely distributing the Xi’an zone, the physical model experiment with geometric proportion of 50:1 is carried out by reasonably simulating the wall rock stratum with a oblique ground fissure, lining structure, stress conditions and dislocation displacement of ground fissures. In the physical model experiment, the angle between axial of tunnel and direction of fissure equals to 450, the additional vertical stress of wall rock soil equals to 50 kPa, 100 kPa and 150 kPa respectively; and the tunnel is simulated with the similar material. The pressure of wall rock, settlement and internal stress of lining structure are measured by the new earth pressure sensor, displacement transducer and strain sensor in the processor of movement of ground fissure, so that the mechanical characteristics of wall rock and lining structure are analyzed well and truly. Test results show that the oblique ground fissure gets a larger sphere of influence on metro tunnel; and the settlement of deformation joints is developing significantly. In addition, the lining obliquely crossing ground fissures is in a force state similar to "beam", which will produce a rotating shift with the uniform settlement of tunnel lining. As to the development of ground fissures’ dislocation displacement, internal forces of lining are changed significantly with the changing of wall rock pressure; and both of the wall rock pressure in the foot wall and the wall rock pressure at the top of lining in the hanging wall increase, while the wall rock pressure at the bottom of lining in the hanging wall decrease. Comparing with the situation of the tunnel orthogonally cross ground fissures, the wall rock pressure and the internal force of lining structure changed larger when the tunnel obliquely crossing the movement ground fissure; and the lining structure is more prone to tensile failure.

In Luanda and its surrounding area, silty sand in red or yellow color is widely distributed. Combining with two projects, based on the results of field investigation, indoor tests, standard penetration tests, plate loading tests, this kind of sand is analyzed. Some conclusions are drawn as follows. Luanda sand has bluff slope in natural situation, and has the special characteristic of collapsibility; and its mechanical properties will be obviously weakened by wetting. As the increase of void ratio, test pressure, content of clay and silt particle or the decrease of water content, the coefficient of collapsibility will be increased; besides, remoulded sand is also collapsible. As for mechanical indexes, will be recovered when water content is decreased after increased; i.e. mechanical indexes are reversible change with water content.

In order to compact the lime-stabilized high water content sludge, 4 different compaction types, having different compactive impulses, were designed by improving the corresponding compaction testing standards and testing instrument. The compaction test was conducted on the lime-stabilized high water content sludge with different lime contents and compaction delay times. By analyzing the relationship between the compactive impulse, the compactive effort and the dry unit weight of soil, a new compaction method fitting to the lime-stabilized high water content sludge was presented; and it was illustrated that choice the compaction method with proper compactive impulse according to the water content ratio ( ) of lime-stabilized sludge and judge whether densification by the change law of the dry unit weight and compaction blows. Based on the engineering practice, the unconfined compressive strength of lime-stabilized sludge at different curing periods was tested; the feasibility of the lime-stabilized high water content sludge used as the fill material of engineering was discussed preliminarily.

The pore characteristics and the change rule of soft soils have significant influence on their compressibility and permeability. The study can reveal the drainage consolidation process of soft soil and its deformation law so as to provide a strong basis for establishing draining water solidifying model based on the pore compression mechanism of drainage patterns and flow model. AutoPore machine made in United States was used to test pore diameter and pore-scale distribution of Guangzhou Panyu silt soil under different load levels, then gave the quantitative analysis of pore criterion distribution characteristics according to the test results. The studied results have shown that: small pores within particles and aggregates intermediated in the range of 0.4-2.5 μm is the largest proportion in the sludge soil; the number of large pores larger than 10 μm and micro pores less than 30 nm is very small; more large pore more easily be compressed and annihilated or splited into tiny pores; consolidation pressure will significantly change pore scale and pore distribution characteristics of the silt soil which results in the changes of its compressibility and permeability. Pore-scale is greater in the early stage of consolidation( 200 kPa); compression coefficient and permeability coefficient are large and rapid decrease with the increasing consolidation pressure; and pore scale is small in the late consolidation( 200 kPa); compression coefficient and permeability coefficient are small, and with the consolidation pressure change flatten out.

In order to solve the problem of optimum supporting design of tunnel engineering with soft surrounding rock, a similar material of model of which the mechanical curve is similar to the origional rock is developed. The physical models corresponding with the cases which are usually used in soft rock engineering such as bolt supporting case, bolt and jetting supporting case , lengthed bolt and jetting supporting case, are made.As well as the bare tunnel case, the four models form a 3D model and are put into the large scale real triaxial physical model machine. So the research on supporting design of soft rock tunnel is base on the same boundary condition of model. The test results demonstrate that various supporting methods lead to various over loaded abilities and various failure character. The similar material is fit for the trait of large deformation of soft rock. The research provides reliable foundation for supporting design of soft rock tunnel as well.

It is of great importance for studying anchoring effect when considering distribution and variation of anchor stress based on creep effect of rock mass; however, there are not many articles to deal with this aspect in recent years. In this paper, we begin with the load-bearing characteristics of anchorage micro-unit, research on variation of anchor stress under the condition of rock mass creeping, then give some conclusions as follows. Force variation of anchor which is embedded in the creeping rock mass has much relationship with stress state and displacement of surrounding rock mass. When anchorage micro-unit is in tensile state; the axial force of anchor is increasing as time goes on. On the contrary, when anchorage micro-unit is in compressive state, the axial force of anchor is decreasing. In terms of stress distribution of anchorage in visco-elastoplastic rock mass, it is concluded to be in accordance with each other between the location of peak stress of anchor and the plastic zone of surrounding rock mass. The conclusion is further verified to be correct by analytical method of engineering. In addition, it is analyzed that the anchor stress is increasing with creeping of surrounding rock mass in underground engineering.

The phenomenon of unloading occurs widely in human project activities and the geological process. The research of rock mass mechanical properties under unloading conditions has been one of the hot topics of engineering all the time. Based on the results of three-dimensional unloading tests, the stress-strain characteristics, the destructions and the law of mechanical parameters variation of sandstone have been discussed and compared with the law of loading tests. It is shown that: the deformation modulus of rock mass can be reduced by 5%-42% at continued unloading condition; the higher the initial confining pressure, the greater the deformation modulus reduced; the relationship between them could be fitted by the exponential function; the peak strain increased linearly with the confining pressure when the rock mass damaged under unloading condition, and the residual strain had no significant relationship with the confining pressure; compared with loading destructions, cohesion c of rock mass damaged under unloading condition reduced by 4%, and internal friction angle ? increased by 12%; the speed ratio of unloading has great influence on the strength and deformation parameters of sandstone; the damage characteristics of rock samples indicate that strong expansion along the direction of unloading and circumferential cracks are presented in process of unloading; different from compression and shear failure under loading conditions, unloading damage is characterized by strong tensile and shear fracture; the higher the initial confining pressure, the stronger the degree of unloading and the higher the degree of fragmentation.

There are many engineering geological problems in the dam foundation; and one new problem is how to evaluate and determine the mechanical properties of the columnar jointed basalt at the dam abutment. Using the true triaxial apparatus is an available measure to study the engineering geological property of the basalt in so compound field environment with high stress conditions and special rock structures. Based on the investigation and analysis of engineering geological condition in situ, a series of physical model tests by brittle material with the true triaxial apparatus were carried out to find out mechanical properties of columnar jointed basalt. The fracture and deformation mechanism of the sample, that is the compound columnar jointed basalt, was studied. Eight different stress ratios( ) are used in the strength test with the true triaxial apparatus; and the results show that the strength and deformation properties of the compound columnar jointed basalt is influenced by the columnar jointed characteristics and the stress ratios. The stress ratios can influence the value of ultimate breaking load of the rock. The test results show that when the stress ratio is less than 3, the stress ratio and the joints control the value of ultimate breaking load and the failure mode. When the stress ratio is higher than 3, the effect of stress ratio is more obvious than that of the joints. With the increase of stress ratio, the effect of intermediate principal stress varies from confinement to load and the ultimate breaking load and the failure mode varies with the change. Six different load models are used during the test; and the results show that the anisotropy of strength and deformation of the basalt is obvious. But if the microfissure distributing widely in the columna is considered, the columnar jointed basalt can be simplified as lateral isotropy.

The reinforcement mechanism and the ultimate compressive strength formula of soilbags in 2D space are reviewed; and the deficiency of the formula is also highlighted. The reinforcement mechanism of soilbags in 3D space is suggested; and two ultimate compressive strength formulas of soilbags under complicated stress situation are derived, which are based on the extended von Mises criterion and the Lade-Duncan criterion respectively. The new formulas are successfully used to predict soilbags’ compressive strength; and their values are verified to be much more close to the experimental measured values from compressive tests on soilbags compared to the values calculated from the 2D strength formulas.

Fully grouted prestressed anchor is a new kind of structural anchor. Few researches have been carried out on analysis of the influence of anchor shape of borehole wall on its carrying capacity. Rolling shape of anchor borehole wall structural plane has self-affine fractal feature; the relationship among structural plane shear strength, liquid injection pressure, tensile load and structural plane fractal dimension D is analysed in detail; the calculation and analysis methods are established respectively. Generally, the applied liquid injection pressure should be less than compression strength of anchoring surrounding rock mass, and tensile load would increase as fractal dimension D increases; the instability judgment criterion of anchoring bearing strata and rock structural plane is determined; the anchoring performance of fully grouted prestressed anchor is discussed. The analysis gives some help for the structure design, test and appliance to the anchor.

During the exploitation of oilfield, the formation pressure depletes gradually, but the effective stress to the rock grain increases. The effective stress may cause rock to deform, resulting in the elastic or plastic deformation; and the rock permeability is quite sensitive to effective stress due to the deformation. Therefore, it is necessary to know the property of stress sensitivity for the low permeability tight reservoir. The permeability of sand rock core samples of Daqing oilfield under different effective stresses is tested, and the reduction property of permeability is obtained. Considering the microscopic characteristics of pore structure and occurrence states of clay, new capillary-tube model is proposed; and the deformation law of single capillary is studied. The research shows that the stress sensitivity of rock increases with the decrease of rock permeability; and there is exponent relation between initial permeability and the loss rate of permeability. The new capillary-tube model can explain the difference of stress sensitivity between low-permeability and medium-high permeability reservoirs based on the microscopic mechanism.

Sound velocity variation is the valid parameter as the token of damage variance. In order to discover the blasting damage cumulative effect and the damage evolutive law of rock mass, sound wave measurement for surrounding rock damage under blasting time after time was carried out at some underground engineering; and the data regression was analyzed at the same time. The corresponding relation between rock mass damage and sound velocity variation under several times blasting was analyzed; and the cumulative expanded models of rock mass blasting damage with the baseline of rock mass sound velocity reducing ratio were founded. Research results show that the correlation coefficient of regression analysis is more than 0.981 6, which illuminate the nonlinear cumulative regression forecast models of rock mass blasting damage founded by test results are correct. The final quantity of rock mass damage is the total of initial damage and blasting damage in the cumulative expanded models of rock mass blasting damage, and where the influences of blasting cumulative damage effect and initial damage are synthetically considered. So the models can reflect the damage degree of rock mass veritably, which are reasonable and feasible.

Saline silt has many special characteristics, such as high salt content, extremely low content of clay and uneven gradation. Due to these special properties, it is hard to compact, so that the strength is very low. In order to understand mechanical characteristics of saline silt, in-situ pressuremeter tests (PMT) and triaxial tests of undisturbed samples were conducted after physico- chemical analysis of this saline silt. The tests results show that the content of soluble salt is 2.9%, and the main ingredients are Cl－ and Na＋. The silt belongs to alkaline soil with chlorine saline. The PMT test results indicate that pre-plastic pressure is 350 kPa and limit pressure is 500 kPa. In that area, pressuremeter and shear modulus can be adopted by 1 750 kPa and 700 kPa respectively. Laboratory test results represent that this soil have strong dilatancy effect. When the axis strain reaches to 12%, the sample will be close to steady state. The peak and residual strength can be achieved to 600~800 kPa and 450~550 kPa respectively when the confining pressure is 150 kPa.

The dynamic motion equations of underground structure under horizontal seismic action are obtained. The transcendental equation for the determination of solution coefficients is deduced by using Laplace integral transform method and linking conditions of structure members. Using inverse Laplace integral transform method the equations for the determination of the displacements of the structure and the poles of the transformation parameters of the Laplace transform are obtained. The further study shows that a special relationship exists between the transformation parameters of Laplace transform and natural frequency of structure : . To avoid the difficulty in determining the coefficients of the solution and the poles of the transformation parameters of the Laplace transform in solving the transcendental equation, the authors suggest that the frequency of structural system is figured out firstly by numerical methods; then the structural displacement and internal forces are obtained by using the residue theorem of inverse Laplace transform.

Researches of dynamic constitutive models for rock materials are the base of theoretical researches of rock dynamic mechanics. Comparing with other nonlinear theories, the damage mechanics proved that it can successfully simulate strain softening and being gradually destroyed of rock materials, and explained its dynamic or static destroying mechanism. The existing dynamic constitutive models which are from theoretical derivation mostly ignore damages, while from experiments are short of damage mechanics theory. Basing on equivalent elastic complementary energy theory and basic concepts of damage mechanics, combining with dynamic experiments, an elastoplastic damage model for rock materials with strain rate effects is established. Comparing with experimental dates in literatures, the validity of the model is proved, so as to found the bases for dynamic response researches of rock material structures.

The residual deformation behaviors of sandy gravel with two kinds of grain size composition were experimentally studied by use of GDS dynamic triaxial system. It is shown that the most residual shear strain and residual volumetric strain under low cell pressure have good linear relationships with lg(1+N ), and they also have linear relationships under high cell pressure when the dynamic stress level is low. But with the increase of dynamic stress level, the dispersion of test results become larger. However, under the same initial state, the resistance of materials to dynamic load becomes stronger with the increase of coarse grain.

In order to comprehend constitutive characteristics of incompact fine sand under compression stress in wide range, experimental tests were performed on a kind of fine sand with testing apparatus of quasi-one-dimensional strain with axial stress up to 1 100 MPa. The stresses related strains of fine sand with water contents of 3.4%, 6.6% and 13.5% were obtained; besides that of dried sand. Based on the test results, empirical constitutive equation is presented as a unifiable form for the fine sand with different water contents under quasi one-dimensional compression. The experimental test data are compared with the data from AUTODYN code. The constitutive parameters of fine sand are recommended, which are indispensable to calculating in DYNA code. The presented experimental test data, acquired under high stress in wide range, can be used for quantitative calculation, and the related empirical formula is applicable for engineering calculation on fine sand with different water contents.

The Zhengzhou-Xi'an passenger dedicated line allows 15 mm settlement of embankment after acceptance. The settlement control of ground treatment in collapsible loess is a key technical problem. Therefore, the settlement of an embankment construction on ground treatment with different measures is observed and researched experimentally in a selected area of typical collapsible loess. The results show that the compression settlement of embankment body is only 3 mm and have already stabilized in 15 days after completion of embankment. The embankment settlement is primarily controlled by the foundation settlement which is determined by the settlement of soils below three different kinds of ground treatment layer. A section of pile thrusted-expanded in column-hammer which treats all 22 m depth of collapsible loess is best, a section of cement soil pile which treats 15 m depth of collapsible loess is better, a section of dynamic compaction which treats 6 m depth of collapsible loess is worst in the settlement, ground treatment and immersion effect. It is very essential that the reasonable waterproof and drainage measures are taken to prevent water from immersing the vicinity of slope foot. The average value of results which are predicted by the hyperbolic method, three-point method and Asaoka method is used as the final settlement of embankment. The constant preloading can be removed to lay ballastless track after 5 months in the section of pile thrusted-expanded in column-hammer and after 8 months in the section of cement soil pile. But it may need to continue for a long time in the section of dynamic compaction.

Coupling behavior of rock and soil mass above the goaf to the surface subsidence can be considered as boundary value problems in the theory of elasticity. The stress boundary formed by unconsolidated soil layers of different characters and the displacement boundary formed between rock and soil mass constitute relevant determining conditions of boundary value problems. According to current research results, a prediction method of the surface subsidence based on the boundary value method was put forward to reveal surface subsidence laws due to underground mining. Some computation formulas for soil displacement and surface subsidence were derived; and the range of the surface subsidence was determined; and an application with the example of surface subsidence for Daliuta 1203 face was presented. The results indicate that the subsidence of ground and soil influenced by rock mass above the goaf depend on structural form of top rock layers, that the surface subsidence influenced by soil mass is related to the soil quality and soil thickness, and the soil subsidence affected by soil mass increases with nonlinear characteristics from bottom to top, until it reaches the extreme on the surface. And it is also shown that the range of the surface subsidence increases with the increasing of soil thickness, and its extension is far larger than the goaf itself.

There exist some problems in the traditional anti-slide pile calculation method; especially for the two row piles, this method cannot be used to calculate the distribution of force and thrust on the piles. It is often analyzed by subjective experience so as to cause unreasonable waste. This paper adopts the strength reduction method of finite element to discuss the change of the force before pile, the force after pile and actual force on the two row piles in three different types of landslide with different parameters, along with the change of two row spacing. Some suggestions of two row piles reasonable stress and position are proposed. Due to the different types of conditions are discussed, so the conclusion is universal, and can provide basis for engineering design.

Based on analyzing the mechanical characteristics and optimum design room of retaining piles structure with interior bracing, a mathematical model of optimum design for the joint of retaining piles-interior bracing is established; and a new objective function and a optimum design criterion are proposed for finding the partial optimum solution to the location of interior bracing on the basis of the fundamental thought of full stress design; three evaluation methods about the equivalent allowable axial-compressive stress ?c and bending stress ?m in the joint are derived and compared; then a application example of a certain excavation in Hangzhou is recommended. The conclusion could be used for reference in optimum design of similar excavations.

The formation and characteristics of T-shaped bidirectional deep mixing column were described. Through huge amounts of standard penetration tests(SPT) on pile shaft and indoor unconfined compression tests, correlations between SPT values and the strength of unconfined compression tests were established, and the correlations between SPT values and the depth of piles were also discussed. Testing method of pile strength and strengths, difference along the pile depth were elaborately analyzed. It was preliminary determined to use the strength of pile to substitute the results of unconfined compression tests in Wuhan New District pile strength investigation project. It is suggested that the weighted average value of pile strengths should be adopted for pile designing and strength testing.

Mashui River large bridge is a key project of the Shanghai-Chengdu national trunk highway; the slope stability of Mashui River large bridge is difficult to be evaluated due to the complex geological conditions and tectonic evolution. How to reflect the geological conditions and tectonic evolution in slope stability analysis is very important for the result objectivity. According to the geological structure and tectonic character of rock mass, the author summarized the deformation and failure mode of the slope. On the basis of the failure mode, the numerical model with finite difference method was built. The stress and deformation state were simulated with the slope under three states, such as in natural state, the action of a bridge and the 50 meters rising of water level. The results indicate that the slope stress field changes very much locally and the influence depth reaches 50 meters. Therefore, an increased cross-section of pile foundation is suggested to improve its bearing capacity.

Focusing on the research hotspot of large-span tunnel passing through coal seams, and taking Chongqing Huanshanping tunnel for example, some works on defining the large-span tunnel and the mechanism of interaction between surrounding rock and support structure was primary conducted, and then on-site monitoring and numerical simulation of the stability of large-span tunnel passing through coal seams were carried out. The results show that the effect of equivalent stress concentration in different part of the tunnel structure has different sensitivities to the change of flat rate, the most sensitive is arch spring, and the crown is the least. Due to sharp stress redistribution when the tunnel is excavated through coal soft rock mass, tunnel crown settlement increases greatly; and the plastic zone can also quickly expand along the coal seam. Specially when the weak coal layer is intersected by the tunnel, the effect of bias pressure becomes much larger and the bias pressure increases with the coal seam steepens, so as to easily lead to the failure of surrounding rock and support structure. Therefore, it should be dealt with carefully during the design and construction.

There are many consequent slope, creep deformation slope and steep countertendency slope during the construction of mountainous expressway. To consequent slope, whether slightly steep slope should be reinforced or slightly slow slope should not be reinforced, the slope expert may give corresponding method which is based on control layer, the engineering geology condition and characteristics. From the devolution of red sandstone tendency and dip angle showing in site, we make conclusion that the slope is a creep deformation slope which is based on many researches on rock characteristics and back analysis of characteristics about slide surface; we emphasize the importance of pre-reinforcement by anti-slide pile; and it is approved by real deformation failure that the analyses and methods made by slope expert is correct. For red sandstone steep countertendency slope, the rock mass strength changes with the infiltration of rainwater for the existence of weak intercalation and joint; and it is important to reinforce the slope which had been in dumping deformation. The slope expert can make comprehensive analysis on the characteristic changing and control factor on stability, and make reasonable engineering method which may reduce the engineering loss.

In the design of underground structure, the action of the side friction is rarely considered and the determination method of the side friction is also not given in the design specification. Therefore, there is no unified regulations on anti-floating safety coefficient which can be ascertained according to the similar engineering practice. In this paper, the structure of the stations in Ningbo urban rail transit project is investigated by using the available experience and the uplift test results. The side friction of the structure is calculated; then the critical width of the station structure is ascertained when the anti-floating safety is considered. The results can provide a little of instruction on the design of metro station.

Based on the in-situ monitoring data of ground temperature along the Qinghai-Tibet Railway, the cooling effects of crushed rock embankments (crushed rock revetment embankment and U-shaped crushed rock embankment) positioned in different permafrost regions with diverse mean annual ground temperatures were analyzed. The comparative analysis showed that either in basically stable low temperature permafrost regions (mean annual ground temperature -2.0 ℃≤TCP<-1.0 ℃) or in badly unstable warm permafrost regions (mean annual ground temperature TCP>-0.5℃), the crushed rock embankment had uplift the permafrost table beneath the embankment effectively; but the two kinds of crushed rock embankment performed different in providing cooling effect. The latter produced more cooling effects than the former; it could keep the deep permafrost thermal stable while raising the permafrost table and cooling the shallow permafrost. Whereas the rising of permafrost table beneath the crushed rock revetment somewhat consumed the cold energy of deep permafrost and consequently made the deep permafrost warmer. The analysis also indicated that the lower the mean annual ground temperature, the stronger the cooling effect of air-convection crushed rock embankment. It should be noted that in badly unstable warm permafrost regions, the crushed rock revetment hadn’t produced enough cooling effect and the underlying deep permafrost warmed considerably; so some enhancement measures are needed to ensure the long-term stability of the embankment.

For the big disaster of landslide, it is important to study the stability of slopes. For the influence factors of rock slopes are numerous and their relationships are very complicated; it can not be solved by traditional methods; so generally based on engineering analogy, the clustering methods are used widely. For the complicated environment influence of slopes, this clustering is a complicated uncertained measurement optimization problem, and can not be solved by traditional methods very well. So, here the clustering uncertained measurement complicated algorithm has been introduced into slope engineering field for the first time. Based on this method, one new method for study stability of rock slope is proposed. Based on analyzing the data of slope examples, using clustering uncertained measurement complicated algorithm, the stability of rock slopes can be estimated. The engineering application can prove that, this new algorithm can automatically sort the slope samples, and the validity is more than 90%, so it is a very practical and new method for slope stability analysis.

In order to analyze sand liquefaction problem efficiently, the stepwise discriminant method was applied to its prediction; the factors with significant discriminant ability were selected to establish discriminant function. A number of site cases were used to verify its validity and accuracy. The results show that: stepwise discriminant analysis model has excellent liquefaction predicting performance; and it can choose effective factors which play a leading role in sand liquefaction. Compared to the distance discriminant analysis, discriminant function based on stepwise discriminant analysis is more stable; and fewer factors investigated or tested are needed, which saves human and material resources for the project construction. Thus it is worthwhile to apply stepwise discriminant analysis to liquefaction prediction widely.

Based on the current status of frequent ground collapse during the urban tunneling, the catastrophe mechanism and control technology of ground collapse induced by urban tunneling are studied combined with ground collapse accident cases. The statistics of 44 safety accidents induced by Beijing Metro tunneling show that there are 16 ground collapse accidents out of the 44 cases, accounting for high percentage (36%). The statistics of 29 ground collapse accidents induced by urban tunneling show that pipeline leakage and unfavorable geologic bodies are the main inducing factors to cause ground collapse, accounting for 69% of all the inducing factors. So the pipeline leakage and unfavorable geologic bodies are the key factors to prevent and control ground collapse accidents. According to the statistical analysis results, the ground collapse forms are divided into three categories as follows: ground collapse directly induced by instability of overlying strata in tunneling, ground collapse indirectly induced by failure of unfavorable geologic bodies in strata in tunneling, and ground collapse indirectly induced by pipeline leakage or damage in tunneling.The catastrophe mechanism and evolution law of ground collapse induced by urban tunneling are introduced by using theoretical analysis and numerical simulation, and then the corresponding measures are put forward to control ground collapse in urban tunneling.

The Xiamen Wuchun highway tunnel of which the span is 34.5 m and only 9 m buried depth, passing underneath an area over 95 sets of buildings within it, the geological condition and environment of the tunnel is very complicated; and the degree of difficulty being under construction is immense also. In order to solve the main security risks during tunnel construction, such as uneven settlement, deformation and destruction of building, we conducted comprehensive research approaches and adopted a set of comparatively perfect safety management system. Firstly, we simulated excavation and reinforce of tunnel construction by using numerical method, and get the deformation values on key construction step. Combining with experiences from other similar projects and national standard, we drew out the control standard values for security monitoring to guide the tunnel excavation and the building protection. Secondly, we carried out thoroughly monitoring to grasp the dynamical response of building, pipeline, ground surface, stratum, surrounding rock and lining of tunnel during construction to ensure security, and implement 24 h automatic monitoring to the key buildings. Thirdly, having built advanced network transmission system of security management, which include monitoring information management, forecasting system and the information announces system with LED display screen; the whole monitoring data and construction proceedings can be stored and processed in data base server, while can be browsed and inquired by the networked computer. Finally, based on the work of third-party monitoring, we built a kind of monitoring management system of III levels warning, which can announce the warning information and construction proceeding to all participant via intranet or LED screen in time.

Using dynamic finite difference software-FLAC, combining with strength reduction dynamic analysis method, a new method for anti-sliding pile aseismic design is proposed. Taking the security and stability factor of the landslide as a discount factor of rock mass parameters, then the rock mass parameters is discounted. Using FLAC dynamic analysis, soil-pile dynamic interaction is considered; the peak internal forces of piles engendered during the earthquake is divided by the coefficient of concrete strength increasing under earthquake, which compared with the internal forces of piles after the earthquake, the larger is considered to be the value of internal forces for aseismic design. While after the piles have been supported, the dynamic safety factor of the landslide should greater than the acceptable value to ensure the landslide would not damage over topping. An example of landslide with pile supported is given. The results show that the strength reduction dynamic analysis method is able to consider soil-pile dynamic interaction, and get the real distributed form of thrust force, so as to provide a new idea for aseismic design of anti-slide piles.

According to a certain accumulation horizon landslide in the logistics park, the geologic structure characteristic and the landslide types were analyzed. Based on the analysis result, the dynamic stability characteristic of the landslide under rainfall was analyzed; and the sliding mechanism and cause were revealed by the theory of unsaturated soil. It considered that the landslide body on groove of the slope surface, steeper terrain, and loose structure and low intensity of the surface accumulation horizon provided convenient conditions for landslide formation. With the rainfall duration increasing, the rainfall was infiltrated into landslide along the surface of the accumulation mass and formed conflux transfixion on the contacting interface between the soil and rock; so the backwater on the contacting interface was formed. As we had known that the backwater decreased the mechanical properties of the landslide and induced the dynamic uplift force in the landslide. Meanwhile, with the rainfall filling the crack and the weak structural plane continually, the dynamic expanding force was induced and the tension crack was enlarged; and the deformation of the accumulation mass was intensified. Finally, the sliding of the landslide was induced.

Excavation damaged zone (EDZ) is an important factor to the deformation and stability of underground caverns. Taking JinpingⅠHydropower Project for example, the distribution and variation of EDZ for large scale underground powerhouse under the conditions of high geostress and low strength-to-stress ratio are analyzed according to sonic wave measuring and multipoint extensometers monitoring; and the parameters of rockmass are back analyzed by BP network and genetic algorithm. The analytical results indicate that the depth of EDZ obtained by sonic wave measuring is consistent with the main deforming depth obtained by multipoint extensometers; and the depth change of EDZ is corresponding with the surface displacement change of rockmass; therefore the variation of EDZ can be analyzed continuously by the integrated using of sonic wave measuring and multipoint extensometers monitoring. Under the condition of high geostress and low strength-to-stress ratio, the depth of EDZ is much larger than general stress condition; and the unloading relaxation becomes the main factor of surrounding relaxation. The depth of EDZ increases with the stress adjustment of surrounding rock during excavating, in which the horizontal extending of EDZ is obvious. The deformation modulus E and cohesion c of EDZ carried by back analysis is markedly lower than undamaged rockmass, while the reducing of friction angle φ is less. Therefore, the grouting reinforcement of damaged rockmass will be benefit to improve its deformation modulus and cohesion; and the stability of surrounding rockmass will be improved consequently.

With respect to shallow depth bored tunnel constructed beneath existing Jiahe road, a comprehensive monitoring the mechanical and deformation characters of the tunnel has been performed during construction., including the ground settlement, crown settlement, convergence, steel support stress, etc. Based on the measured data, the deformation and stress properties of surrounding rocks and supporting system are analyzed. The interaction time-space range and the control method in the construction of shallow depth bored tunnel in loose ground are presented. Meanwhile, the real-time monitoring information is applied to optimizing the supporting system. The experience and conclusions will enrich the theory of shallow depth bored tunnel. The results can be adopted in the design, construction and monitoring.

We mainly made a design and implementation of construction monitoring geology and geographic information system for underground engineering (MGGIS). First, we analyze the characteristics, the structure，the function, the platform and the related technologies and define the access format for data to obtain and store. After that, we present a detailed design and implementation of three functional independent subsystems respectively: working processes project display, flat space-time effect and cross-section diagram subsystem. This is as far as we know the first proposition to use B/S framework geographic and geologic engineering information system for underground construction features via RIA technology. The scheme proposed can display the precise spatial information of changing environment in the construction of underground engineering，which is appropriate to the risk management of underground construction. With the advantage of being easy to use, interactive and fast running, our system is superior to old types of geographic and geologic information system. The achievement of our research has been used in Beijing Rail Transit Project Security Risk Monitoring System, Nanjing Metro Project Security Risk Monitoring System and other related projects.

The characteristics of load application and the demands of blasting vibration are analyzed; and the equivalent load application method is proposed based on Saint-Venant principle, that is getting blasting loads equivalent first, then applying the equivalent loads to the line or area of centers of the same blast hole row, in order to simulate blasting load[8]. The results of numerical calculation show that the equivalent method has differences in the vicinity but better fit in further zone. With this equivalent method, the influence of blasting construction of foundation trench of immersed tunnel on the stability of embankment is calculated and analyzed by three-dimensional solid numerical model; the vibratory responses of different positions and different depths are calculated; and based on this, vibration reducing measures are also researched in order to reduce the influence of blasting vibration on existing constructions, so as to provide a reference for similar projects.

With the increasing of mining depth, thick overburden becomes the main feature of deep underground mines. By geophysical surveys, deformation monitoring, as well as the theoretical analysis, mechanism of surface subsidence caused by underground mining in a typical thick overburden metal mine was analyzed. The results obtained show that goaf in thick overburden provides space for ground subsidence; and smaller thickness of the gob creates condition for the development of ground subsidence, which is the main reason for surface subsidence. After surface subsidence occurred, centering on collapse pit, the range of subsidence continues to expand outward. Because of the strike of goaf and geological defects, such as faults and rock interfaces, collapse pit expands faster in the north, west and south than in the east. Rainfall will increase the expansion speed of the collapse pits, because the infiltration of surface water accelerated the movement and subsidence of the surrounding rock and soil toward the pit.

Based on engineering practice in tunnel-type anchorage for Aizhai suspension bridge,the interaction mechanism of tunnel-type anchorage with undercrossing tunnel were obtained by numerical analysis in MIDAS/GTS.The results show that asymmetry interaction exists between tunnel-type anchorage and undercrossing tunnel in excavation stage; namely, the effects which tunnel-type anchorage acting on undercrossing tunnel is more significantly than its back face. In addition, the nodal displacements nearby the anchorages was changed obviously by the undercrossing tunnel; and in consequence,the vertical displacement curve of tunnel-type anchorage occurred sinking and rotating but there is some limited influence on the horizontal displacement; the vertical extra displacement can reach 0.76 mm because of the undercrossing tunnel. Finally, it is found that the blasting vibration which caused by development blasting of the undercrossing tunnel is weak in view of the tunnel-type anchorage, the vibration velocity less than 2 cm/s when the blast center distance exceeds 40 m; it is anastomosed with the measured data, the monitoring data show that the vibration effect is negligible to the tunnel-type anchorage when the blast center distance exceeds 40 m.

Based on the distance discriminant analysis model of rockburst prediction, and combined the characteristics and the principle of Bayes discriminant analysis theory, a Bayes discriminant analysis method to predict rockburst in underground engineering is presented. Some main control factors of rockburst, such as the values of in-situ stresses , the compressive strength and tensile strength of rock, the elastic energy index of rock , are selected as the discriminant factors of the Bayes discriminant analysis model; and the resubstitution method is used to estimate the ratio of mistake-distinguish. The data of a series of underground rock projects at home and abroad are taken as the training and testing samples. Rockburst of three tunnels are used to verify this model. The results show that the Bayes discriminant analysis model of rockburst has excellent performance and high prediction accuracy.

The stability of excavating the variable cross-sections cavern is one of the important research topics about the underground engineering. Particularly for weak surrounding rockmass, it may bring insecurity and instability to excavate the cavern from the small sectional-section to the big. By means of the numerical analysis of finite difference, the stability of excavating variable cross-sections cavern was studied; and effects of two construction methods about the advanced support using the ductule grouting or without the advanced support on the engineering were analyzed. The results showed that it’s more unstable when excavating the cavern from the small cross-section to the big; and the advanced support can considerably improve the stability of the surrounding rocks and reduce the deformation of the cavern, and also avoid the collapse of cavern excavating in weak rock. The results are the some meanings for the construction of similar caverns.

The disaster causes of gushing water and sand during shield departure from shaft are analyzed; and the finite element model of shield departure construction is established using Midas-GTS software. Considering coupled seepage and stress of shield departure construction, the groundwater permeates from reinforced soil around underlying layer to wall is analyzed; and the settlement of the undisturbed soil in front of the reinforced soil is studied. An example is given to demonstrate that: supposing the reinforced soil is impervious, the accident that water and sand inflows from tunnel portal is influenced by length of soil reinforcement and groundwater level; increasing the length of reinforced soil is good for engineering safety; but the cost is high. Decreasing the groundwater level could reduce the disaster of gushing water and sand during shield departure from shaft. Reasonable construction parameters for a project are determined by taking into account of economy, security and time limit.

Artificial freezing water sealing reinforcement method for water-enriching layers of Shang－Xin tunnel of Nanjing metro Line No.2 is proposed. Numerical model of freezing temperature field is built for the water inflowing tunnel by ADINA software. The effects of distance of freezing pipes, brine temperature and diameter of freezing pipes on development of freezing walls, thickness of freezing wall and average temperature are studied. On the basis of this study optimization design is implemented. And the freezing method is successfully applied to the construction. The study demonstrates that the application of artificial freezing can solve this special geotechnical problem. The distance of freezing pipes should less than 1 meter so as to get effective freezing wall. Using brine temperature of -30℃ may not only meet the need of cooling capacity but also meet the economical requirement. There is no significant effect on the thickness of freezing wall and the average temperature by using freezing pipes of large diameter.

The mud-rock loosening deposit which has the basic character of granular mixtures is easily turning into debris flow if inspired by rainstorm. Based on the discrete element method and its superiority on round particles moving and mutually affecting and big distortion question research. In order to analyze the relationship between the moisture content and the process of loosening deposit forming in the mud-rock flow, this thesis simulated the process of loosening deposit turning into debris flow under condition of rainfall by using the two-dimensional particle flow code software-PFC2D. Result showed that the particle would start moving and accelerating then caused the displacement increasing, induced the chain destroy process and mechanism of landslide and debris flow when the water content surpassing the critical moisture content.

Mined fracture is the passage of gas flow, and gas flow law is the precondition of control gas disaster. Based on the dynamic failure process and coupled fluid-solid interaction between gas flow and solid deformation, considering geologic condition and excavating technique in Mine No. 5 in Pingdingshan, a numerical simulation model is established with the gas-solid coupling rock failure process analysis system RFPA-Gas to simulate the stress variation law, roof and floor deformation, fracture evolution law, displacement in the protected seam, change in gas permeability and gas flow law during upper protective layer extraction. The simulation results reproduced stress variations in coal and rock strata, roof and floor deformation and fracture evolution process during protective layer extraction. The movement of rock strata were characterized by upper three zones and lower two zones: caving zone, fracture zone and bending subsidence zone in the vertical direction in the overlying stratum; floor deformation and failure zone and elasto-plastic deformation zone in the vertical direction in the underlying stratum. The gas flux, gas pressure and gas permeability change with the upper protective extraction. And the gas permeability of protected coal seam dramatically increases about 2 500 times. The tensile-shear gas flow passages appear under the pillar between compression zone and expansion zone. The gas flow speed and the flux reduce at the stress-concentration zone. The expansion zone is composed of stress relief and sudden expansion zone and stress relief and steady expansion zone. The gas flow speed and the flux increase dramatically at stress relief and sudden expansion zone. The gas flow speed and the flux increase slowly at stress relief and steady expansion zone. The gas outburst often occurs at stress relief and sudden expansion zone. The results provide a clear direction for gas control in the protective layer. The simulation results are in good agreement with the stress-relief effects in field.

The traditional cavity expansion theory, which is based on the isotropic initial stress in soil layer, could not be used to the situation with anisotropic initial stress in soil layer. A two-dimensional undrained numerical model is conducted to simulate the pressure-controlled cavity expansion process with anisotropic initial stress. Through analyzing the cavity shape, the distribution of plastic zone and excess pore water pressure, the characters of the pressure-controlled cavity expansion with anisotropic initial stress is obtained. The results indicate that the radial displacement, plastic zone and excess pore water pressure around the cavity is not equal in all directions in case of pressure-controlled cavity expansion with anisotropic initial stress, which is different with the traditional cavity expansion. The results also show that the plastic zone of cavity expansion with anisotropic initial stress is larger than that of cavity expansion with isotropic initial stress. It is concluded that it would be unsafe if the traditional cavity expansion theory based on the isotropic initial stress supposition is used to analyze projects with anisotropic initial stress.

The aim of this paper is to obtain quantitative information of the long-term mechanical behavior of a concrete-faced rockfill dam (CFRD), particularly the effect of rheological deformation on the performance of CFRD. Some numerical simulations have been conducted for a CFRD of a Pumped Storage Power Station in China by ABAQUS finite element code. A modified double-yield surface rheological model incorporating nonlinear strength is applied to describe the long-term mechanical behaviors of the rockfills. The instantaneous plastic deformations of rockfills are determined by the modified double-yield surface model; and the time dependent viscoplastic deformations of rockfills are defined by the empirical equations of exponent function. The predicted results of finite element analysis (FEA) present the evolution of the stress and deformation of dam body, dam element and face slab at the construction, impounding and operational stages. From the results of FEA, it has been shown that the rheological deformation of rockfills at the operational stage has a remarkable effect on the stress and deformation of CFRD. The results or conclusions in this paper are beneficial to further knowledge, reasonable prediction and optimizing design of the long-term mechanical behavior for CFRD.

Numerical methods (finite element method, finite difference method, etc.) can be used to calculate stress, strain and failure of slope; but it is difficult to calculate the safety factor of slope stability directly. Limit equilibrium methods can obtain the factor of safety, but they need to assume the interslice forces, which affects the calculation accuracy. Based on the stress field obtained by numerical methods, by defining the maximum thrust forces and improving numerical simulation method of conventional critical slip field of slope, the critical slip field method of slope based on numerical stress field is proposed. The results obtained by using this method for two examples have been compared with other methods. It is shown that the proposed method combines the advantages of numerical method and limit equilibrium method so as to find the critical slip surface of slope accurately and conveniently, and give more reasonable safety factor.

High filling often causes proof earth pressure concentration which leads to proof cracking, in order to obtain measures to reduce the proof earth pressure on the top of culvert, the mechanism of culvert-filling-foundation working together is studied. The earth pressure concentration factors of the culvert influencing by the effects of loose mid and real side, flexible filling, fill in after excavation, as well as the foundation treatment measures are analyzed by numerical simulation. It is shown that the measures can effectively reduce the pressure at the culvert roof, the slope of excavation should be vertical and the width of excavation should be equal to the culvert width during digging after filling. Ground treatment measures of culvert should be flexible and extend to a certain width outside the basement. The results can provide references for high-fill culvert pressure reduction and foundation design.

The hole between the electromagnetic wave CT method can not only detect and igneous rock formation in the karst rock weathering interface detection, has broad application prospects. Foundation for the power station on the left felstone igneous rock formation, rock containing quartz, feldspar, montmorillonite and other minerals, together with stress easily hidden weathering weak interlayer interface and a direct impact on dam safety. Made between the use of continuous improvement of the hole electromagnetic method and the CT processing software, data obtained from the inversion of the imaging. The results show that the absorption coefficient value of the observed specimen test results shows good agreement. In the detection of three pairs of drilling section, digital images are given a clear structure and the weathered rock layer interface depth, drilling results have been validated for the Zuojiang river dam foundation grouting curtain depth to provide a reliable basis.

In order to get better interpretation effect, based on the theoretical analysis and formula deduction of magnetic field intensity from radio wave penetration for coal face, it is found that the variation of magnetic field intensity values are mainly controlled by the geometric positions of observation spots within the normal range of coal face, but are mainly controlled by the path length of geologic anomaly and the absorption coefficient of magnetic wave energy when the observation path of field intensity through the area of geologic anomaly. The product of magnetic field intensity H and its path length R can be named as M. Thus, the M values can be regarded as constant within the normal range of coal face, but will be greatly lowered within the abnormal range. The coal face can be divided into many units in order to carry out the computerized tomography inversion of M value; then the M values of every units will be acquired by the special software. Subsequently, with all of the inversion values divided by the average width of coal face, the image of measured field intensity for coal face can be gotten. The surveying results from Zhangji Mine had given clear geologic anomaly areas of coal face, which have been well testified by coal mining. As a new interpretation means，it has been broadly applied to radio wave penetration for coal faces.