For reducing the construction risk of undersea tunnel, insuring the tunnel to smoothly pass through each weathering zone, and resolving the technical difficulties to obtain rock mechanical parameters, the dynamic back prediction model was established based on the displacement back analysis. As a comparison, an overall optimization method on elastoplastic back-analysis is briefly presented. Combining the hydrogeology exposed by advanced service tunnel, back analysis was carried out on the basis of the vault settlement and around convergence displacement by practical monitoring measurement. Then, the mechanical parameters would be obtained; that is, equivalent elastic modulus and confinement pressure coefficient of surrounding rock after primary support. Furthermore, in the similar geological conditions, boundary element method was used to normally simulate left and right main tunnels immediately after face advance and primary anchor bolt-shotcrete support. The normal calculation results could provide quantitative basis for comparison and selection of construction schemes of main tunnel, and adjustment and correction of support parameters of main tunnel. It realized the dynamic information design and construction. The analysis of engineering example indicates: it is reliable to obtain the equivalent mechanical parameters of surrounding rock by displacement back analysis. In similar geological conditions, the equivalent mechanical parameters can be used for normal calculation of main tunnels; furthermore, to forecast their deformations and failure modes, and estimate their surrounding rock stability. Displacement back analysis is a bridge which associates theoretical analysis with engineering during tunnel construction, and supplies a practical way for engineering design, construction and decision-making.

The catastrophe theory is applied to analyze the mechanism of floor water-resisting key stratum instability induced by dynamic disturbance during coal mining;and the double cusp catastrophe model is proposed for instability analysis of floor water-resisting key stratum above confined aquifer under dynamic disturbance in order that the complicated dynamic failure process of floor water-resisting key stratum is described. By using catastrophe theory analysis a new criterion for dynamic instability of floor water-resisting key stratum is given. It is proved that whether failure of the floor water-resisting key stratum being occurred depends not only on the key stratum feature but also on the size and way of exterior loading. And the vibration frequency of floor water-resisting key stratum is affected by static load such as confined aquifer pressure. Moreover, dynamic response of floor water-resisting key stratum loaded by static pressure such as confined aquifer is different when dynamic disturbance including different amplitude, different time and different frequency is loaded to floor water-resisting key stratum.

Aimed at the weakness of ignorance of secondary consolidation in traditional 1D finite-strain consolidation theory, a novel coupling model for 1D finite-strain primary-secondary consolidation was presented, according to both the finite deformation theory in continuum mechanics and the consolidation theory in soil mechanics. Using excess pore water pressure as governing variable, the presented model could be formulated respectively with Eulerian, Lagrangian, and solid volume coordinates. Such factors as the change of unit weight of soil, solid phase velocity, settlement rate of ground surface, change of ground water table, change of surcharge and secondary consolidation, are explicitly expressed in the presented coupling model. Under different conditions, the new model could be reduced correspondingly to related models by previous authors. When taking no account of the secondary consolidation effects, the presented model is equivalent to that by Gibson et al. (1967). From viewpoint of engineering convenience, the simplified form of the presented model considering secondary consolidation and the change of surcharge keeps more easily to be solved, and provides a practical model for further reference.

The characteristics of load–settlement curve of gravel soil and the collapsibility and collapsible mechanism of gravel soil were studied based on the results from plate loading tests under different work conditions, routine soil tests and soluble salt tests. The study shows that when the gravel soil stabilized under the load of 200 kPa, then immersed in the water and loaded to 400 kPa, the load-settlement curve is a broken curve, and can be obviously divided into three phases: compressive deformation phase，collapsible deformation phase and composite deformation phase. The gravel soil with 4m thick has collapsiblity and its collapsibility is uneven. The collapsible mechanism of gravel soil is due to its loose single-grain open structure. There is open pore in the frame grains and some of open pore is filled with sandy grain aggregation; frame grains are linked together with point-to-point contact or mainly connected with cement consisting of clay particle, clay minerals and soluble salt. During the process of ponding and loading, the film water around clay partvicle is becoming thicker, the clay minerals expands itself and soluble salt dissolves, so as to lead the loss of the cement strength and destabilization of the structure; and thus the gravel soil collapses.

A steaming humidifying method is proposed for humidifying unsaturated undisturbed loess sample; and the testing steps and testing parameters are given. The effectiveness of this method is verified by checking whether the distribution of moisture is uniform and whether the soil density has changed. The measured results of moisture content show that the results from microwave oven method meet the required precision; but the results from alcohol burning method have greater error at higher moisture contents. Strength index for unsaturated soil after freezing and thawing is measured on undisturbed soil samples with different moisture contents obtained by using the steaming humidifying method. The results reveal that the freezing and thawing effect has no influence on the cohesion of loess when the moisture content of unsaturated undisturbed loess sample is very low. However, when the moisture content is higher, the cohesion of loess decreases after freezing and thawing, the lower the freezing temperature and the more freezing-thawing cycles, the greater the decrease in cohesion. The internal friction angle of loess increases after freezing and thawing, the lower the freezing temperature, the greater the increase in internal friction angle. The internal friction angle has almost no change after freezing-thawing cycles when the moisture content is low. When the moisture content is higher, the more freezing-thawing cycles are, the greater the increase in internal friction angle is.

Based on the discontinuous sub-block model brought forward in the first part of this paper, the object-oriented numerical simulation program is developed with the Visual C++ program language. The feasibility, validity and precision of the numerical simulation program are proved through some classical validation examples. At last, the numerical simulation program is applied to the failure simulation of a masonry arch bridge. The advantages of discontinuous sub-block model to deal with the failure of material are proved by comparing with the simulation results from other methods and discussion.

The stress condition of surrounding rock is very complicate under different construction phases and it is important to study the permeability of rock under the complex stress path. In order to study the relation between stress and permeability of marble, triaxial permeability test under general and loading-unloading of confining pressure on the basis of constant axial strain, (which is called strain in the following text) are carried out. Based on triaxial permeability test results, some conclusions can be drawn as follows. (1) In the general triaxial permeability test, the characteristics of permeability-strain curve of marble has three significant phases: the lowest permeability, the highest permeability and the stable permeability. (2) The permeability of marble decreases with the increase of (the absolute value of axial stress minus confining stress), following the law of exponential decay; (3) For the same value of , permeability of marble during the loading of confining stress phase is greater than it in the unloading of confining stress phase; (4) The variation of will influence the permeability of marble significantly when it decreases to a certain degree. (5) The permeability of marble will increase when decreases; and the recovery capability of permeability of marble will reduce with the increase of axial strain.

Four different scaling methods are used to scale a coarse-grained soil into a grading with smaller particles. The methods are mixing method, scalping method, equal-weight replacement method and similar grading method. The biggest grain size of each soil after grading is 10mm, 20mm, 40mm and 60mm, respectively. A number of relative density tests are conducted. To further analyse the test results, more relative density for other three soils with arbitrary grading are performed. The maximum and minimum dry density tests are carried out using vibrating method and loose filling method. The relationship between maximum or minimum dry density and the soil grading parameters, maximum particle size is investigated under the same compactive effort. A normalizing method is presented to express the relationship between dry density and grading. The relationship of dry density versus Cu, Cc and maximum particle size is found. According to the relation, the maximum dry density of the real gradation can be determined.

In the geological environment, the rocks show many complex engineering features and phenomena, both associated with its form and change of internal fine structure. The characteristic parameters of rock microscopic structure are given quantitatively; and its relationship with macro-mechanics is studied, and then to further understand the mechanics of rock deformation. In order to research the relationship between rock mesomechanical structure and macroscopic mechanical behavior, the technique of SEM is applied to marble fracture of surrounding rock in diversion tunnel of a hydropower project; and a lot of information of SEM in fracture is obtained. The main research content is information abstraction and measurement of mesomechanical structure with computer image processing and analysis techniques and pattern recognition principle. By the quantitative experimental study of rock microscopic structure; it is a great significance to learn from the microscopic scale that the failure mechanism of rock. It also has an obvious reality to analyzie and evaluate engineering properties of rocks and the adaptability of the construction.

Internal water pressure is one of the main kinds of loads acting on hydraulic tunnel, which consists of lining and surrounding rock. The axisymmetrical model is adopted and the corresponding formulas are carried out. The radial stress on interface is assumed as the flag to tell the combined bearing capability of lining and surrounding rock. Then the influence of rock permeability and deformation modulus on the combined bearing characteristic of lining and surrounding rock is discussed. The design method and process are described in detail. According to the limit of maximum width of concrete crack, a program to calculate pervious lining stresses and to carry out the reinforcing bars design is developed and compiled. A certain tunnel is analyzed as an example and a certification of design program is provided. Finally some conclusions are drawn as follows. Rock permeability is as important as deformation modulus in tunnel lining structure design. The possibility of lining deviating from rock becomes larger when rock permeability becomes poorer and deformation modulus softer. And the possibility of lining deviating from rock also becomes larger when the concrete cracked. A great amount of steel can be saved through the reinforced concrete lining scheme than the steel lining one. To enhance rock integrity and impermeability, some advices are suggested, such as reducing excavation disturbance, adopting fine and complete consolidation grouting.

All characters of acoustic emission in the procedure of rock stress-strain have been studied experimentally. In initial consolidation and elastic phase, it is found out that hits seldom happens, energy keeps low, amplitude is small and no event is produced. In strain hardening phase, hits instantly increases, energy go up, amplitude enhanced and events happen. In strain softening phase hits decreased, energy became low, amplitude went back small and events happen. Due to the differences among acoustic emission characters in individual rock-transforming phases, acoustic emission method can be used to study micro-damage evolvement and predict macro-destabilization of engineering rockmass on spot. Based on research result of 3D damage localization in rock acoustic emission, the development of damages characterizes in fractal and statistic self-similarity. Besides, the event evolvement in rock acoustic emission can be described with chain growing model: activation-growth-activation. Through event number, the evolvement of tiny cracks in rocks is observed, and described it with Logistic equation logistic. Rock damage evolvement has furcation and chaos characters.

By using a new apparatus called 80t 3D Multifunction Apparatus for Soil mechanics, 3D cyclic behavior of gravel-structure interface was studied under three typical normal boundary conditions generally used in laboratory experiments. The test results indicate that the normal boundary condition has great influence on the behavior of the interface, which presents similar or different behaviors: (1) Volume or volumetric trend of the interface generally presents compressive response due to shear application, but the values are different. (2) The curves between shear stress and tangential displacement are unclosed in the same cycle and not coincident in different cycles, except those under constant normal stress condition. (3) The curves between stress ratio and tangential displacement are all closed, coincident and like ellipse under different normal boundary conditions. (4) The monotonic and cyclic friction angles of the interface are similar, but the cyclic shear strengths are significantly different.

A lot of research work shows that when rock undergoes plastic deformation, its elastic parameters vary. In order to study the elastoplastic coupling characteristic of rock, cyclic loading experiments on two kinds of marbles are carried out. The experiments show that comparing with conventional triaxial experiments, cyclic loading experiments do not influence the deformation and strength of the rocks. The elastic parameters obviously vary with plastic deformation. When taking the elastoplastic coupling character into consideration, bulk modulus and shear modulus are more suitable to be selected as elastic parameters than elastic modulus and Poisson ratio. The variation of the parameters of strength with plastic internal variable is also obtained under the hypothesis of Mohr-Coulomb yield criterion. The results can provide experimental basis for the furthur study on the elastoplastic coupling constitutive model of rock.

Behavior of compression type rock anchor cable in soft rock slope is studied by field test. Experimental anchor cables which have 130mm diameter holes and 6 steel strands are frequently used in anchorage of rock mass engineering. Various fixed anchor length and free anchor length are designed to find the whole loading-displacement relationship of test rock anchor cables. Strain sensors are put into cement paste to test the strain distribution curve of fixed anchor length. Test data coincide with theoretical results. The optimum fixed anchor length of experimental anchor cables is 2m. Ductility and residual strength of anchor cables are also excellent. Anchor cables still keep high bearing capacity when they have large displacement, which can also provide early failure warning. According to experimental strain data, stress transmission length become longer when bonded transmission length doing so. The failure of anchor cables has two stages of the partial plasticity and the whole plasticity.

Rock mass is a combination of blocks and interfaces. Discontinuity of displacement field is caused by local shear deformation along interfaces, which has great influence on mechanical performances of rock mass. Discontinuity on slip plane is depicted with an assemblage of continuous functions, and mathematical model which is capable to consider local shear deformation along interfaces is obtained. Analytical solutions of surrounding rock bearing capacity of circle tunnel are deduced using the model when the stress-slip curve of rock has a strengthening phase. The influence of slip planes in rock on bearing capacity of surrounding rock is studied. It is concluded from analysis that the self-bearing capacity plays a great role in stabilization of deep tunnel surrounding rock, which is remarkably affected by strengthening phase of stress-slip curve. There are direct relations between surrounding rock pressure and depth or dimension of tunnel as well as physical or mechanical characteristics. The formation of unstable dynamical response is controlled by rock mass parameter m, which has relation with softening degree on interface, energy translation, geometry size of dissipation structure and elastic modulus.

In order to reveal the regular influence of freezing-thawing cycle on shearing strength properties of road slope soil in seasonally frozen area, unconsolidated-undrained test was carried out on saturated undisturbed silty clay under different experimental conditions such as freezing and thawing temperature, freezing-thawing cycle index and open or closed system. The test results indicate that after freezing-thawing, cohesion decreases, but internal frictional angle increases; the lower freezing temperature is, the less influence of freezing-thawing cycle on cohesion and internal frictional angle is. As freezing-thawing cycle number increases, after 5-7times, the changes of shearing strength properties gradually become stable. Water supply can reinforce the influence of freezing-thawing on C and ; thawing temperature has a slight effect on the shearing strength properties of saturated undisturbed silty clay.

According to the nonlinear creep properties of earth-rock aggregate embankment after construction, a modified Kelvin model that can express nonlinear viscoelastic deformation of material is presented. Based on the current research results of the creep mechanism of earth-rock aggregate embankment, the creep settlement after construction is considered to be an attenuation creep process; and the modified Kelvin model, generalized modified model and recognition method of model parameters are presented. Through analyzing the modified Kelvin model, the results show that: the nonlinear constant is an important influencing factor to the model; and long-term strain of the modified Kelvin model is smaller than that of Kelvin model. Based on the creep test data in the related literatures, parameters of modified Kelvin model are fitted; and the fitting effect is well. The modified Kelvin model will distribute theoretical basis for the numerical calculation program of nonlinear viscoelasticity.

The dynamic torsional shear triaxial tests are carried out on loesses of Lanzhou, Luochuan and Yangling under different water contents and different stress states; and then the dynamic shear stress-strain curves of loesses are obtained. Besides, according to Hardin-Drnevich hyperbolic model, the soil structural quantitative parameters, which are based on the dynamic shear stress, are developed; and the dynamic structural characteristics of unsaturated loesses in Lanzhou, Luochuan and Yangling are analyzed by using the parameters. Results show that the structural parameters of Lanzhou, Luochuan and Yangling loesses firstly reduce along with the increase of the dynamic shear strain; and then remain at a stable level; water content and consolidation stress have significant influence on the structural parameters. Under the same consolidation stress condition, the lower water content, the greater dynamic structural parameters of the loess; and under the same water content, the smaller consolidation stress, the greater dynamic structural parameters of the loess. In conclusion, under the same condition, the dynamic structural characteristics of Yangling loess is the strongest; the following is Luochuan loess; and Lanzhou loess is the weakest; in other words, the structural characteristics of loesses in the geographical spatial distribution exists a law of increment from the northwest to the southeast.

Being different from general mountain tunnel by NATM, the lining of underwater tunnels built by mining method may be sustained heavy external water pressure; and underwater tunnels are more affected geological uncertainties and risks, particularly when passing through the saturated stratum such as the weathering deep slot stratum F4 in Xiamen undersea tunnel. Based on fluid-mechanical interaction model for saturated ground conditions, the three dimensional numerical analyses are conducted to investigate the relationships between the pressure behind the lining and the discharge water inflow for different drainage conditions. The results show that the water pressure trapped behind the support depends on the discharge capacity of the drainage system relative to the water inflow from the ground, even the reduction of 80% external water pressure is obtained while the discharge water flow being controlled about one-third of the full water inflow from the ground. From the view of reasonable design of seismic water loads behind the lining, the reduction coefficient of 0.2 is regarded as the acceptable level for controlled drainage underwater tunnel. The emphasis is placed on introduction of grouting circle in support system for weathering deep slot stratum F4，but if competent ground conditions are anticipated to be encountered during underwater tunnel construction; then grouting circle may not necessarily be required. In view of the disadvantageous distribution of deformation and internal forces occurred in the invert, particularly in the corner position of invert connected with the side-wall; therefore, whether it is waterproof-type tunnel or drainage-type tunnel, more attention is paid on design of invert form and support.

Fill road embankment aside riverbank or widen riverbank as road embankment is often used in highway extend. The road embankment along riverbank built has what influences to the stability of riverbank, and has what characteristics of the stability, deformation and destroy mode to the road embankment. These are the main problems to be solved in river levee highway extend. Based on the results of local reconnaissance and in-situ as well as laboratory test, a finite element model is built to carry out analogy calculation and analysis of the stability of the riverbank and the road embankment under different water level before and after the road embankment built. The results indicate that: the build of road embankment is propitious to enhance the stability of the riverbank, the safety factors are increased about 26%; the embankment built aside riverbank is easy to generate differential settlement and big settlement. The total settlement could increase 35% as the widen of embankment. the road embankment can occur whole shear destroy on the slope far from the dam, and the seepage has little influence to the stability and would not change the destroy mode of the embankment. Numerical simulation can disclose the stability and destroy mode of the road embankment before the project built. Simulation results could offer reference and gist for the next engineering countermeasure design.

Combining lots of the failure investigations of surrounding rock in soil tunnels and model test, the failure location and state of soil surrounding rock were researched. The failure modes of soil surrounding rock and their definition were discussed according to the failure location and state. The results show that the failure modes of soil surrounding rock include un-supported section failure mode, tunnel face failure mode, the failure mode which un-supported section and tunnel face destroying at the same time and no destroying failure mode. Un-supported section failure mode can be divided into self—stability failure, footage failure and no failure. The main control factors of self-stability are the span and high of tunnel and the condition of soil surrounding rock: but the condition of soil surrounding rock and footage are the primary control factors of footage failure.For tunnel face failure mode,the failure surface shape approximates to logarithmic spiral curve or inclined plane; for un-supported section failure mode, the failure surface shape is a parabolic curve;and intersecting curve of logarithmic spiral curve or inclined plane and parabolic curve for the failure mode which is un-supported section and tunnel face destroying at the same time.

Considering uncertainties and spatial variability of soil parameters, the reliability analysis method can reflect objectively the real safety character of retaining structure for foundation pit engineering instead of the safety factor method. The reliability index increased and the variability of soil parameters decreased after being reduced by the random field theory. Compiled with project example, this paper provided the detailed analysis of the mean value and the variability of the design parameters which affected the stability of soil foundation pit. The results show that, the sensitivity of the parameters of cohesion c, angle of internal friction φ and the embedded depth hd which affected the reliability index β was much more than those affected the safety factor K. The reliability index β was affected significantly by the coefficients of variation δc, δφ, and δhd. The δq affected the reliability index β obviously when μq was large. It’s reasonable to appraise the overall stability of retaining structure of foundation pit by reliability analysis method than by the safety factor method.

The viewpoint that earth pressure acted on breast board is lesser when flexiboard is used in sheet-pile wall engineering, which is expounded based on the load distribution and deforming characteristic of board between two adjacent piles. There are some problems which exist in simplified granary method and unloading-arch theory; therefore, the model tests for simulating the flexiboard sheet-pile walls used in reinforced fill foundation on ramp are designed to primarily research and compare earth pressure distribution patterns when flexiboards are fixed on frontal or dorsal suiface of piles. It is indicated that both of earth pressure acted on flexiboards and their deflection deformations are lesser; moreover , soil arching effect is more intensive, when the flexiboards are constructed on the frontal surface of piles according to testing results of dial indicators and earth pressure cells. The measured soil pressure distributions of flexiboards almost present parabolic curves, whereas dorsal load ditributions of piles are complex. In addition, the comparison and analysis are made about two theoretical calculation values and testing results. Finally, the time effect of earth pressure variation is studied by monitoring earth pressure cells when flexiboard is on the dorsal suiface of piles; this process that has been lasting for 21 days since boulder strips had been stacked on fill foundation.

The rapid development of infrastructure in the western area of China leads to the construction of more and more high fills. Accurate information on the shear behavior of the fill materials becomes a key issue for a safe design and construction. A series of large scale triaxial tests have been conducted on Douposi moderately-to-slightly weathered fill materials, which is a weak rockfill mainly found in Yunnan province. The test results show that the shear behavior of Douposi moderately-to-slightly weathered fill materials is very different from other typical rockfills, with a low shearing strength, while the stress-strain relationship, stiffness and strength characteristics are more similar to those of fine grain soils. Furthermore, water can reduce the strength of Douposi moderately-to-slightly weathered fill materials significantly, which must be taken into account during design and construction. Finally, it is demonstrated that the Duncan-Chang model is capable of simulating the shear behavior of Douposi moderately-to-slightly weathered fill materials.

Several stable and continuous weak-soft zones exist in the Third segment of Triassic Badong Formation strata (T2b3) in New Badong county. The characteristic of weak-soft zones was studied by drilling core analysis, surface investigation, X-ray diffraction (XRD) , scanning electron microscope (SEM) and physico-mechanical experiment. Based on geological prospecting data of monitoring profile (300m deep) the paper indicated that 13 strips transfixion weak and soft zone existing in the T2b3 strata can be divided into weak intercalation being rich in clayish fine, cataclasite weak and soft zone, corrosion transformation weak and soft zone and soft rock weak and soft zone according to the substance in weak and soft zone and structural characteristics. The weak-soft zones are composed of illite, chlorite, quartz and calcite etc, whose clay mineral has difference contents and could is more than 70%. The weak-soft zones undergo interlaminar shear failure and influence surrounding rock mass which form fracture cleavage or cataclasite zone. The microstructure of weak-soft zones shows that the scratch and mineral’s directional alignment are obvious; it is indicated that the weak-soft zone experienced bedding-parallel shearing slip and local gravitational creep structure of shoreline slope. Test results show that shear strength becomes lower once the i weak-soft zones attract water to saturation and repeated shear. The weak-soft zones will aggravate deep deformation of shoreline slope under long term soak when storage water level is uplifted to 175m in Three Gorges Reservoir.

Based on considering tapered pier behavior and the soil-pile interaction,bridge pier and group piles are simplified as global properties;and then an analysis model of tapered pier supported by group piles is presented; Secondly, analysis model is decomposed into two subsystems: elastic deformation of bridge pier and rigid deformation of group piles,the natural frequencies of which are solved by finite element method and energy method. Further,the global natural frequency of tapered pier is deduced by using the Southwell frequency composition method. Lastly, the comparison between calculated results and the real engineering examples shows that the method is reasonable;and the analysis results of the parameters of pier in natural frequency could be available for some reasonably conclusions.The results show that it is more practical in consideration of the pile-soil interaction and the geometry nonlinear of tapered pier. The influence of pile- soil interaction on natural frequency of tapered high pier could not be neglected in study.

Based on the field tests of the retaining wall with tenon，strength reduction finite element method had been developed to analyze theoretically limit sliding resistance force of the retaining wall with tenon of 0.0m,0.7m and 1.0m length. The sliding failure mode of the retaining structure with tenon was studied. The sliding resistance mechanism of the tenon of the retaining structure in the soft ground had been researched. The integrated stability safety factor of the retaining structure with tenon was put forward. Research showed: the results of theoretical research could be a good characterization of field test results. The retaining structure with tenon was damaged from sliding into overturning with the increase of tenon length. The application of the strength reduction finite element method to retaining structures limit design is entirely reasonable; this method could be applied to the engineering design of retaining structures with tenon.

Due to the high organic content, strong adsorption capacity and low permeability, dredged soil can be used as a kind of additive to clay liner of landfills. The changes of physico-mechanical properties of the silt clay and the mixed soil (silt mixed with dredged soil) before and after cation adsorption have been investigated. The permeability and shear strength, two basic issues of the quality of clay liner, have also been studied. The hydraulic conductivities of the crude soil and the mixed soil increase with increasing quantity of cation adsorption on the soils. However, the hydraulic conductivities of the mixed soil is less apt to be influenced than that of the silt. After adsorbed with cations, both the frictional angle and the cohesion force of the silt clay and the mixed soils increased at first and then reached a peak, whereas the increases of the cohesion force of the silt clay as well as the frictional angle of the mixed soil were comparatively more. In a word, the addition of dredge to silt could improve the effect of cation adsorption on permeability and strength of soil. SEM photo were conducted to evaluate the changes of microstructure of soils. The relevant impacts were further discussed by means of electrostatic double layer theory.

Pile driving engenders disadvantage influence to stability of warf slopes，first it brings the excess pore water pressure in the soil around pile to sharp increase; and this leads to decrease of the effective stress; second vibratory acceleration owing to piling brings adverse instantaneous inertial force to stability. The first is primary for stability of insensitive soil slopes. Distribution of the original excess pore water pressure has been studied; and based on popular expression of Biot concretion differential equation, analytical formula for excess pore water pressure resulted from pile driving has been set up. Considering disadvantage influence from piling, formula of safety factor of stability was set up based on strip dispart method. Stability analysis on a wharf slopes has been done considering sequence of driving construction; result shows that safety factor reduces evidently，excess pore water pressure dissipates gradually; and factor varies with working procedure of driving. In period of construction slope is most dangerous because of accumulation of the pressure value; and the excess pore water pressure dissipate mostly after three months since finish piling, safety factor approximates the value that calculated without taking influence of piling into account. So it is important to check stability of slope during driving.

Combining the construction of Yunling Tunnel of Shiman Expressway, the form and developing process of floor heave in tunnel are described. Several factors affecting floor heave are studied. By analyzing the stability of the invert of tunnel, a formula for calculating floor heave is obtained; and then verified by the data of spot monitoring. By analyzing the mechanism of floor heave of tunnel, the deformation damage mechanism of rock mass is understood correctly and the disposal measures of floor heave are prescribed. The research not only can provide basis to optimize the supporting system of tunnel, but also to guide construction process and insure constructive safety.

Basing on the assumptions of exponential fluid and narrow plate model, formula of climbing height in base post-grouting is deduced. It is shown that the climbing height is mainly related to grouting pressure, pile length, pile diameter and mudcake thickness. The climbing height increases with the decrease of soil deformation modulus and pile length. And it increases with the increase of grouting pressure and mudcake thickness. At last, the formula of climbing height is verified by case study.

A new wave arrival time difference detection method based on cross-correlation functions for shear wave velocity measurement in single-hole method is introduced. As the difficulty to analyze the arrival time difference of shear wave velocity, the multiple cross-correlation function is used to get the arrival time difference of two similar shearwave velocities. We need do multiple-auto-correlation function to the signal with big noise to get high SNR. Cross-correlation function can get the arrival time difference of two similar signals, but the error is always too big when the nose of signal is big. The auto-correlation function can do multiple auto-correlation analyses; and the cross-correlation also can do multiple cross-correlation analysis with multiple auto-correlation function. The experiments indicate: multiple cross-correlation function can increase the SNR and get the arrival time difference precisely of the signal of shear wave acquainted by trigger and the shear-wave acquainted by probes. Based on this principle, an expert recognition system to calculate shear wave velocity is designed. This system can automatically analyze the shearwave velocity of every measured point and make a complete report.

Based on structural characteristics of lining joints of shield tunnel, a mechanical model of joint was established. The interaction between segments is transformed into a series of combined shearing and normal springs. The model was then implemented into FLAC3D code and the spring stiffness could be adjusted automatically under diverse deformation styles of lining joints during processing. Both the transverse and longitudinal structural behavior could be simulated in terms of the internal forces and deformation of shield tunnel. Finally, the model was validated by a whole ring test on Shanghai Yangtze River Tunnel lining. A good agreement between tested and calculated results was obtained to verify rationality of the algorithm.

A combining micropiles structure is a new retaining and reinforcement structure for slopes. This structure consists of several separated micropiles connected by a roof plate. The structure has the advantages of small pile diameter, easy and quick construction, operational safety and low cost. It can be applied to a moderate or small slope or landslide control projects. In particular, the structure is very suitable for dealing with project emergencies. According to the general load features of the structure, it is put forward that the part of the structure above the slip surface of a landslide may be regarded as a single rigid frame under landslide thrust. The part of each pile above slip surface can be analyzed by m-method in terms of elastic foundation-beam theory after the combined structure is equally deposed. The pressure on each pile by soil or rock mass among the piles above the slip surface are considered. Furthermore, the part of each pile below slip surface can be analyzed by k-method in terms of elastic foundation-beam theory. In this way, internal forces of the structure can be obtained after several iteration calculation. Analytical results show that each micropile in the structure is loaded by an axial force, a bending moment, and a shear force, but the axial force is principal. The new structure and its analytical method are successfully used in practice for a cutting slope in Guangyuan–Bazhong expressway project in China’s Sichuan Province. The performance of this structure is verified by experiments.

Nearly for more than ten years, lime-fly ash soil has generally made the road subbase and basic unit due to its low construction cost, advantageous to the environmental protection, the long-term higher strength characteristic. the dynamic triaxial tests for different mixing proportions of soil and lime-fly ash soils to study lime-fly ash soils content influence on the dynamic parameter; and several kinds of mixing proportions test results are given for comparison and reference. The test results indicate that the lime-fly ash soil contents of larger than 40%, is not suitable otherwise the significance is not big, and is uneconomical.

Pile-plate structure is a new technology dealing with the soft soil foundation in high-speed railway practice in order to adapt to the strict deformation standards. This structure is composed of rigid pile like CFG ,PHC and 50cm plate on the top of piles; it can be used to control the embankment settlement of soft soil. Two centrifuge tests were done about the plate on the top of the piles to analyze the function of the plate for soft soil embankment settlement of high-speed railway. The results show：While the concrete plate is covered on the top of the piled-foundation, the soft soil embankment settlement is reduced about 12% and its settlement is more uniform. The soft soil changes from soft-plastic condition to hard-plastic; and the density and water content are changed obviously; the depth of the engineering load affected is over 40m.

Owing to abundant argillaceous minerals, argillaceous rocks often take on notable dilatability, in particular the lower diagenesis argillaceous rocks formed during Mesozoic and Cenozoic, which is the main type. After general analysis of existing discrimination factors, it is presented that the montmorillonite content, cementation coefficient and surface area are as three main indices for dilatability identification and grading of argillaceous rock. According to projection pursuit cluster statistical method, some analyses of twenty samples coming from Daban tunnel in China’s Xinjiang Autonomous Region are done. Based on moving average trend line of the sample's projection value, these argillaceous rocks can be divided into four grades, just as no-swell, micro-swell, weak-swell and strong-swell, which is approximately in accord with the result by dry block saturation water absorption index, so, here the factor and distinction way are reliable.

On the base of meeting bearing capacity control and the requirement of settlement control, we complete the optimization design of the deep-mixing pile composite foundation by using numerical stimulation to analyse the optimal pile length and pile spacing, in order to satisfy the construction demand and meanwhile to save the construction expenditure as much as possible. According to the characteristics of the deep-mixing pile composite foundation, we have analyzed the settlement composition, discussed in depth the computational method of both the settlement and the characteristic value of composite subgrade bearing capacity; in addition we have evaluated compressibility of the reinforced area and the subjacent bed through the unit cell method and the layer-wise summation method. Concerning the index and numerical parameter of the bearing capacity, the load pressure ,also the design considerations of the deep-mixing pile composite foundation, we get the minimum pile length which satisfies the bearing capacity by setting optimal pile length and pile space. Through the calculation of computer programs, we get the optimal data combination of the basal area, the rate of displacement and the pile length which coincide the requirement of the bearing capacity; the optimization design of the deep-mixing pile composite foundation has been realized.

In order to describe the force-displacement relationship of geotechnical granular medium under stress wave, an elastoplastic contact model of low velocity impact is derived according to the theories of contact mechanics and rigid dynamics, in which the local nonlinear dynamic interaction of granulae is considered and the coefficient of restitution is introduced. Then the rationalities of the contact model are verified by several examples. The results show that the complicated incremental formula and the problem of nonlinear dynamic contact have been avoided in the contact model; and the effects of many factors such as impact velocity, physico-mechanical property, geometrical characteristic and exterior physical condition of the granulae during contact are taken into account; therefore the contact model is convenient for engineering application.

Evaluation of the stability of surrounding rock is a complex system problem of uncertainty. A new model for evaluating stability of surrounding rock is established based on the projection pursuit(PP) optimized by the particle swarm optimization(PSO) and the attribute interval recognition model(AIRM), which is named as attribute interval recognition model based on projection pursuit weight(AIRM-PPW). Based on the analyzing of main influencing factors of surrounding rock stability, five indices are chosen as the evaluation indices. The attribute measurement interval of single index is computed through constructing the attribute measurement interval functions and the synthetic attribute measurement interval is calculated by the weight of PP. The confidence criterion and the score criterion are used to recognize the stability of surrounding rock. The result from case study indicates that the model is effective to evaluate the stability of surrounding rock with reliable conclusion. Moreover, using weight of PP, the model could avoid subjectivity and arbitrary in the process of determination of index weight, and ensure objectivity and accuracy of the evaluation.

PLAXIS is adopted to simulate the mechanical behavior and deformation of retaining structure for foundation pit in excavating process. In order to reveal the deformation and internal force of surporting structures, the different heaped loads are considered. The analytical results show that there are great differences between the mechanical behavior and deformation of surporting structures on both sides with the same design parameters. So it is necessary to calculate and analyse surporting structures two sides separately while designing the unbalanced foundation pit.Meanwhile, some conclusions are drawn on performance of supporting structures and deformation of foundation pits through the calculation and comparison.

Natural characteristics analysis of wholly grouted bolts in soil medium was presented,and a calculation formula of natural frequency and natural vibration type was derived. For the lack of experience about the applicability of permanent anchorage in vibration environment, a dynamic test of one field under train excitation is conducted to avoid anchorage-train resonance.The results show that the first order longitudinal natural frequency of anchorage, field predominant frequency and train dominant frequency distribute in different frequency band,and train excitation causes no resonance effect with anchorages. Ralated researchs provided a important reference method for preceeding research on the applicability problem of bolt support structure in complicated environment.

Coal and gas outburst is one highly nonlinear behavior of coal-gas system far away from equilibrium, which is the most complex dynamic disaster triggered by underground mining. Chaos theory is briefly reviewed first, and evolution process of coal and gas outburst is analyzed based on this theory. It is thought that coal and rock system is in a chaotic state of lower nested tier before outburst, and during outburst a series of simplified coal shells are avalanching burst in a short time, holes are formed in a rhythmical fast iterative stage of intermittent chaos state; and the system is in a stable equilibrium state after outburst. The behaviors of outburst occurrence, development and termination, based on the universal properties of various nonlinear mappings in describing complex problems, can be expressed by the intermittent chaos state iterative computation which uses the Logistic function and the composite function as kernel function. The primary formulas of relative hole depth and outburst parameter in kernel function are given. The conclusions are helpful to deepen and abound the understanding of physical essence of outburst.

A numerical method to identify the range of excavation damaged zone (EDZ) induced by underground excavation and blasting is put forward. Firstly, the numerical approach for analyzing the underground excavation and blasting is presented based on three-dimensional elastoplastic FEM considering damage. This approach introduces how the blasting load, gravitational load and excavation load are calculated, applied and iterated. The influence of excavation blasting on surrounding rock stability and the effect of anchor support measures are both properly reflected. Based on the measurement method of EDZ in engineering practices, the threshold value of damage coefficient is obtained. Therefore, by employing the distribution of damage coefficients derived from numerical analysis, the range of EDZ of surrounding rock can be identified. A case study is conducted. It is discovered that the ranges of EDZ derived from numerical analysis and in-situ measurement agree well with each other; and the errors are within an acceptable range. It is therefore concluded that the proposed numerical method is effective to identify the range of EDZ of underground caverns induced by excavation and blasting.

The upper bound limit analysis approach, which is based on the upper bound theorem, is one of the familiar methods for slope stability problems. The key of the approach is the construction of kinematically admission failure pattern. According to the Mohr-Coulomb’s yield criterion and its associative flow rule, a novel slope stability analysis method is presented. In the method, the collapse mechanism is assumed to be in the form of rigid blocks analogous to slices in traditional slice methods and takes the translational and rotational velocities of slice into account at the same time. The purely translational and purely rotational velocity fields are two special cases of the presented mechanism of failure. Numerical examples illustrate that the proposed approach gives lower factor of safety than the purely translational one, and the results are also compared with those given by the conventional limit equilibrium method.

On the basis of the full study on the chinese and foreign information about the effective stress in porous media, the 2D and 3D fractal calculation models for the effective stress in deep porous media are respectively established by using fractal geometry theory. It considers the rock characteristics of the deep complex structure in petroleum engineering. The models can show the stress relationship in any pore structure rock and are the improvement to the existing model about the effective stress. In order to facilitate the on-site applications, the simplified models are further given for the effective stress fractal models in porous media. The examples of calculation shows that the culation errors for the simplified models are less than 7% and can meet the requirements of on-site oil field.An effective stress profile can be obtained by applying the simplified models to the logging data.

Taking the deformation characteristics of large displacement, large strain, permeability-consolidation and time-dependence of soft soil into account, the finite element method (FEM) formulas and iterative solution strategy were built, in which the soil skeleton was simulated by visco-elastic-plastic model. The embankment construction process was simulated by dynamic “birth” and “dead” elements and the double nonlinear permeability-consolidation analysis method was established. Then the FEM program LSVEP was developed. The foundation settlement was predicted by using parameters from laboratory tests and back analysis separately; and the results were compared with monitored data. The results indicate that: the large strain visco-elastoplastic FEM built in this paper is reasonable and the precision of settlement prediction was affected markedly by the choosing correctly of calculating parameters. The settlement predicted by parameters from back analysis is much more close to those monitored settlements, it is an effective method to improve the precision of settlement prediction and can be referenced by similar projects.

In the construction of the pedestrian underpass of underground excavation with shallow overburden，it is crucial to rationally delimit the size of digging length. If the size of digging length is too small, the construction time will be prolonged and temporary protection will increase. If the size is too large, the earth on the top of the tunnel will be unstable, even collapse. Based on Terzaghi’s loose medium theory, a calculating formula of digging length in homogeneous soil is proposed and applied to layered soil. Some valuable conclusions on the shallow underpass construction are proposed through the simulation of finite difference method of Qingchun underpass; and their comparisons are made.

Through the constructing of the finite element-element free Galerkin coupling method of Biot’s two phase mixture theory in u-p formulation, the numerical simulation for liquefaction problem is carried out. The cyclic elastoplastic constitutive model and updated Lagrange formulation are jointly adopted to establish the governing equations. The coupling method can avoid computation break caused by element distortion when using finite element method and save computation time. A numerical example shows that the method for liquefaction analysis is feasible and effective.

A quasi static finite element method for stability analysis of the large cylindrical structure considering the cyclic weakening effect of soft foundation under wave load was developed by combining the concept of cyclic shear strength with D-P yield criterion. Then the proposed method was numerically implemented in the framework of the general-purpose FEM software ABAQUS. According to a project, the stability of the large cylindrical structure was analyzed. The results show that the stability safety factor of the large cylindrical structure decreased obviously when strength weakening of soft ground was considered while increased remarkably when the soft clay was reinforced by driving drainage plate. And the stability safety factor of the large cylindrical structure increased obviously with the increment of reinforced depth for the same embedded depth of the large cylinder. Weakening degree of the stability safety factor of the large cylindrical structure is 30% when strength weakening of soft ground is considered; so it is suggested that the strength weakening of soft ground should be considered in practical design. Besides, reinforcement of soft soil by driving drainage plate is an effective way to increase the stability safety factor of the large cylindrical structure when the soft ground can't satisfy the bearing requirement of the structure.

For excavation of rock mass in complex geological body, simplification methods of the numerical models are often utilized in that accurate models are difficult to construct. However, the reliability and accuracy of the computed results rely heavily on the model. A new method is proposed to construct the FLAC3D model which can depict the geological body and excavation of rock mass accurately. Geological and excavation surface models are built from their boundaries to define the three-dimensional domains. Then, TetGen is used to generate the constrained Delaunay tetrahedralizations (CDTs) and quality tetrahedral meshes. The input and output data structure of TetGen is analyzed to transfer data from surface model to TetGen and from TetGen to FLAC3D model. The FLAC3D model of a deep mining copper mine is constructed, including several strata and 63 stopes. The results prove that this method is simple, feasible, effective and robust.

Analytical solutions of equations, which described one-dimensional consolidation of unsaturated soil using mixed compressible fluid method, were educed. The effects of parameters of soil on one-dimensional consolidation of unsaturated soil were discussed based on the above analytical solutions. It is confirmed that the formula for evaluating the pore-water pressure in unsaturated soil by the method is almost identical to that of Terzaghi theory, which is often used in analysis of one-dimensional consolidation of saturated soil, except for the Bishop effective stress parameter which describe the effect of pore-air on pore-water in unsaturated soil. In the formula of computation of pore-air, there is not only Bishop effective stress parameter describing the effect of pore-water on pore-air, but also compressibility of the pore-air that affect the rate of consolidation of unsaturated soil. In all the factors that influence the rate of consolidation of unsaturated soil, the most important one is the seepage path of fluid.

Mass concrete temperature cracking is an important problem of concrete dam safety in hydropower projects, which exists from construction process of concrete dam to operation period. This paper introduces the simulation method of mass concrete temperature cracking propagation process by element-free Galerkin method(EFGM). Due to its no-remeshing property, EFGM is very suitable for cracking problem. The governing equation of EFGM is presented for concrete heat conduction problem. It is discussed how concrete cracking process brought from temperature decrease is simulated by EFGM. The algorithm process is also presented. Then a numerical simulating program is developed; and an example including an initial crack is computed to validate the program. Result shows good accuracy and reliability of this method; and concrete cracking process brought from temperature decrease may be simulated effectively by EFGM. The cracking propagation process of concrete block accords with general crack distribution rule.

According to the relationship between stress boundary time-history and speed boundary time-history in dynamic analysis, stress time-history of dynamic boundary condition is transformed into speed time-history. A new method to calculate soil vertical displacement is proposed, for which simplified and multi-angle comparison study is done. On the basis of stress and vertical displacement calculation in Qian Jiahuan’s model, sine load and triangular load forms are introduced; and two simplified calculation methods of vertical displacement are derived. Two methods are clear and simple and the same, except the difference in coefficients. The engineering example shows the vertical displacements calculated by two methods are close to the measured displacements, but the displacement method under the sine load is better to reflect the actual situation.

The wall surface displacement growth and the stress change in the filling of gabion retaining wall during construction process are researched. Based on the theory of particle flow code (PFC), one of the discrete element methods, a series of numerical compression tests are simulated to establish the proper mechanical parameter values for filling, filling stone, gabion. The real gabion retaining wall being prototype, the model of gabion retaining wall of back ladder model is constituted. The mechanical behavior of retaining wall is studied during the uniform load acting on the surface of filling. The simulation results show that: (a)The sensibility of horizontal stress to uniform load decreases with the increase of depth in the filling; and the stress increases earlier and more in the lower filling depth. This is because that the upper layer filling consumes mostly energy of uniform load; and the lower layer filling absorbs a small quantity of energy when macro displacement occurs in the upper layer of the gabion retaining wall.(b) The most displacement of retaining wall occurs in the filling stage. Construction management of gabion retaining wall should be emphasized. (c) The displacement is comparatively large in the upper, lesser in the lower layers not only in the filling stage but also in the concentrated uniform load; from this, it can be seen that the destruction form for gabion retaining wall of back ladder is overturning. The results provide a foundation for studying the active earth pressure of this gabion retaining wall.

The earthquake induced liquefaction of embankment is analyzed using the effective-stress based fully coupled dynamic analysis method. Special emphasis is given to discuss the effect of waterproof carpet paved on the slope of the upstream. The behaviors of the foundation soils are described by means of a cyclic mobility constitutive model which was developed at the bases of modified Cam model by introducing concepts such as stress-induced anisotropy, over-consolidation, and structure. Results show that the phreatic line become lower due to the effect of the waterproof carpet, which increases the initial effective stress of dam foundation and reduces the possibility of liquefaction. Furthermore, the deformation is reduced effectively.