The instabilities of the rock mass slope with regular weak intercalated layers are discussed；and a slope of swallowtail catastrophe model with the catastrophe theory is established. The jump property of landslide of the rock mass slope with one weak intercalated layer on the basis of slope swallowtail catastrophe mode is studied；and the probability of jump property of the rock mass slope with multiple weak intercalated layers on the basis of extreme points of potentials is qualitatively analyzed. The results show that the latter swallowtail catastrophe model potentials have four extreme points at most，and that the slope state would change with the amount of extreme points of its potentials.

Transient pulse method is a newly developed technique in rock seepage tests to measure permeability of rocks. The theory of fluid dynamics in porous media is applied to analyze the hydrodynamic characteristics of transient method in rock seepage tests. It is identified that，in the momentum equation，the variation of flow velocity is able to be neglected for seepage in rocks. High-speed non-Darcy flow as shown by Forchheimer¢s equation is insignificant for seepage in tight rocks and Darcy Law is normally valid. As one of the fundamental hydrodynamic equations describing the transient seepage in rocks，the continuous equation is applied to explain the change of pressure in the rock seepage tests with initial and boundary conditions. Physical and mathematic models of the transient method are presented. Interpretative formulas are derived for time-dependent pressure curves at several controlled conditions of the upstream and downstream reservoirs，with the assumption of equal pressure gradient. This assumption simplifies the solution process of partial deference equation in the mathematic model. The interpretative formulas provide conveniences for the analysis of the test process and calculation of permeability with defferent control methods：(1) water capacities of both the upstream and the downstream pressure vessels are fixed；(2) water capacity of the upstream pressure vessel is fixed and the pressure of the downstream boundary is constant；(3) flux of water from the upstream pressure vessel，which is determined by moving speed of the plunger，is constant and the pressure of the downstream boundary is constant. For the third control method，a formula is derived to predict the decrease of the pressure in the upstream reservoirs after stopping the plunger from moving. Validity of the interpretative formulas is identified by the well fitting of the pressure-time curves in permeability test cases for the three types of control methods. It shows the application of the assumption of equal pressure gradient.

The rock salts from Yingcheng mine of Hubei Province and Jintan mine of Jiangsu Province were studied through uniaxial compression，triaxial compression and Brazilian tests. The properties of short-term strength and deformation of the two rock salts were analyzed. The experimental results indicated that the rock salts from two different places exhibit similar mechanical behaviors though there are some quantitative discrepancies. The failure of two kinds of rock salts can be described well by Mohr-Coulomb failure criteria. The results also indicated that the rock salts have considerable plastic deformation capability and dilatant deformation capability；and the rocks behave obvious strain hardening characteristic under high confining pressure. The presented results can be expected to provide useful references to the stability analysis of rock salt in underground engineering and the site selection of energy storage in rock salts.

An optimal design method of reliability for soil nailed walls is proposed. This method can ensure the safety of the soil nailed wall in excavation and operation，such as：(1) there is enough bearing capacity of the nail head for each excavation stage and in operation，and the yield strength of the steel bar for the nail is not exceeded，(2) there is sufficient safety factor of the slope stability of soil nailed wall for each excavation stage，and (3) an optimal design method based on iteration process is adopted that the most economic design of the soil length and steel bar diameter are achieved. This method incorporates the dynamic relationship between the location of the slip surface，the nail length and the diameter of the steel bar in each excavation stage and operation. The method is applied to a case record for illustration of its capability. The case record involves a failed soil nailed wall in the loess deposit in China. The cause of failure was analyzed，which reveals some deficiency of the existing method of design which doesn¢t consider dynamic relationship between the location of the slip surface，the nail length and the diameter of the steel bar and the stability in each excavation stage. The wall is redesigned based on the proposed method and has been constructed successfully. The proposed method can be a useful reference for engineers in design and construction of the soil nailed wall.

On purpose of studying the thixotropy character of saturated silt in Yellow River Delta and searching a new in-situ measuring method to test the state change of silt，the electrical resistivities of different sections in some 50 cm-long silt soil samples were tested，which were sampled vertically from silt soil layer at different spots of the Yellow River estuarine area，when they were being librated vertically and after the libration stopped. On analysis of key factors influencing the resistivity variation of saturated silt，it was revealed that the state of silt soil would vary along depth with time during being librated vertically and after the libration stopped. During being librated vertically，the top section of silt soil layer will become melting until hydro-state which makes resistivity of this section decrease，while porosity of the bottom section of silt soil layer decreasing and the resistivity of this section increasing. But the resistivities of different sections would not vary with time while being continually librated vertically，which shows the state of silt soil will not vary continuously as being librated vertically. After the libration stopped，the varied silt soil will transform to the original state. Relation between resistivity and time shows the varied silt soil will keep the new state for about 2 hours firstly ，then transform to the original state slowly in 6 hours. The cutting picture of librated silt soil sample proves the analysis of state transform of slit soil is validity with resistivity method.

Theoretical equations by analyzing earth pressure balance(EPB) shield cutterhead¢s cutting the ground are deduced and the numerical model is set up. The simulating test platform and two simulating tests of two different types of cutterheads are introduced，and the torque of the cutterhead of the simulating EPB shield 1 800 mm in diameter is calculated according to the simulating experimental. Furthermore，the torques of the cutterheads of some domestic and those of overseas earth pressure balance shields are compared；and the computational results are verified with the field data. As a result，the equation of the torque of the cutterhead of EPB shield is proposed. It shows that the accurate result can be achieved according to the theoretical analysis and equations. The result can provide reference to practical engineering projects.

Typical area in Yellow River estuarine tidal flat is chosen and studied. The dynamic response process of saturated fine grain soil and the Penetration stress，peak strength，residual strength，the variation of sensitivity，and the influence of the variations of pore water pressure and the liquefied layer on the liquefied process of the silt soil in the area under cyclic loading are investigated and compared by real-time monitoring of pore pressure，static cone penetration test，vane shear test and the geotechnical test. Results show that the change of soil structure has close relations with the characteristic of energy absorption，the response of pore pressure under cyclic loading. The liquefaction of the silt soil in the area of Yellow River delta happens in hard crust mainly due to the cyclic loading. With the increase of the cyclic number，the liquefied layer extends to deep site. The changing tendency of the physical index of soil mass shows obvious difference with the change of depth due to the action of cyclic loading.

The light and soft behaviors of the cantilever retaining wall have the characteristics to be adapted to the alternant deformation，but its height is limited. How to utilize its higher ability of safety against overturning and against sliding and self-weight of backfill to improve its height at the same time is a new issue. So a new structure of more-step cantilever retaining wall is studied. Starting from the new structure of cantilever retaining wall，two-step cantilever retaining wall is brought forth. Deformations of retaining back and stresses of backfill have been analyzed by elastoplastic numerical calculation model to simulate construction conditions. The boundaries between backfill and retaining wall，and backfill and floor are simulated by interface elements aiming at reflect interaction of them. In addition，along with the analysis of the mechanical behavior of the cantilever retaining wall and deformation test results from Qinghai—Tibet Railway，its application as a new retaining structure in permafrost regions is discussed. All these work can provide references to future engineering practice.

Large-diameter cast-in-situ thin-wall tubular pile is a new kind of pile and has been put to wide use in the treatment of soft soil in expressway，dam，embankment，and excavation due to its advantages of cost-saving，fast construction，high quality and less environmental pollution. Usually，the bearing capacity of pile is caused by end-bearing capacity and the frictional resistance between soil and pile. Hence，how to evaluate the outer and inner friction resistances is the key point. So far little progress has been achieved. Whether soil core should be taken into account and how to rectify the end-bearing capacity and friction resistance are still under consideration. This is the main reason that the results deduced from present methods are far away those from the measurement. Based on the load transfer mechanism，five methods from domestic and overseas researches have been analyzed and compared with two case studies. In all these methods，ICP method turns out to be the best one and can be easily used. Its calculation result coincides with the measurement from static loading test，which demonstrates that this method is worthy to be used in practice.

Through a great deal of calculations，the relationship between defect degree and ratio of amplitude was studied，in which the influence of the characteristics of the soil around piles is considered. By means of theoretical analysis，the influence coefficients of a reduced neck defect or a neck-expanded defect to the next one are derived under the condition that the pile has more defects. The theory and method for determining the defect degree of the pile foundation with more defects are discussed，in which the method of regaining the energy of elastic wave and recurrence formulae are developed. In the time domain，the quantitative analysis of pile with more defects is realized with low-strain dynamic test. Finally，model pile test was performed to prove the accuracy of quantitative analysis theory.

The static and dynamic similarity theories of structure experimentation model are presented by combining the equation analysis with dimension matrix analysis. The similar relationships between static and dynamic models，ratio of similitude，and similarity criteria of Dongtinghu three-tower cable-stayed Bridge in Yueyang City are deduced. The self-oscillating character and the dynamical response under the action of seismic wage of the prototype and the model are compared and analyzed based on finite element technique. By numerical analysis，the results of rigidity similitude model are deduced. As reasonable additional mass upon the model structure，the dynamical capability and dynamical response of the prototype meeting the requirement of engineering precision can be gained. For the additional mass question of large cable-stayed bridge model，the dynamical capability and the response of the bridge¢s tower and cable with or without additional mass under the action of three-dimensional earthquake wave are analyzed and compared. It shows that the structure design of model bridge satisfied primarily rigidity similitude. According to the similitude ratio and similitude criterion，the test results can be modified by the additional mass. It can provide references to the design and dynamical examination of structure.

Full-scale friction experiments of concrete block reinforced earth retaining wall between the block and geogrid are modeled on the special testing machine. The size of block which the interface of block and geogrid is the surface of 500 mm is 500 mm×500 mm×220 mm. The number of experiments is 96 and the laid dry and mortal masonry are divided. The force of friction，coefficient of friction and the influence factors are analyzed. The experimental study indicates that the force of friction increases with the vertical pressure increasing and the frictional connection reduces with the vertical pressure increased，but there are not linearity relationships，there are well logarithm relationships between force of friction and vertical pressure，coefficient of friction and vertical pressure respectively. The calculating result of a concrete block reinforced earth retaining wall with adjusted size of concrete block shows that the interval space decides the confine in which the frictional connection between block and geogrid can be used. The test results are useful for engineering practice.

As a type of new flexible protective material，geocell has broad application in slopes of highway. Eroding model experiment shows，by adding geocell，not only can the total average erosion rate be decreased to 48% but also gulches development and evolution are weakened，thus the collapsing of roadbed is avoided. Foundation bearing capacity of saturated loess test indicates，by the same way，that loess slopes of highway will double or treble its capacity and limit its failure to local or slobaal shear failure. Many practical engineering examples have proved，as a type of flexible protective material，that geocell has good effects on slopes of highway.

Based on the express way project on soft soil operated for 4 years，the information construction method is fully analyzed，such as inspection during the period of fill and preloading on soft soil，deformation of the pile of bridge，presetting flip-height，presetting compensatory fill for settlement，secondary excavation etc.. With the use of key control section in the inspection，the express way on soft soil can be constructed effectively. It does good to vehicles jumping at bridge approaches with the use of presetting flip-height，presetting compensatory fill for settlement，and secondary excavation etc.. The method of information construction is the key to the construction of express way on soft soil. Good effect is gained on the soft soil treated with plastic drainage belt combined with surcharge preloading. Under the condition of low embankment and shallow soft soil，deep cement mixing pile is a quick and effective method to meet the post construction settlement of express way. Under the condition of low embankment and shallow soft soil，it should be cautious of the soft soil treated with plastic drainage belt combined with weight preloading.

The dynamic mechanical behavior of C30 concrete is investigated in one-dimensional stress state under a wide range of strain rates from 10－4 s－1–102 s－1 by using an improved SHPB technique and Instron Servo-hydraulic testing system. According to Johnson-Cook¢s strength model，the strain rate coefficient and related material constants of C30 concrete subjected to large strains，high strain rates and high pressures are determined experimentally. From a large number of experimental results for C30 concrete，it reveals that the damage evolution is a rate-dependent process，which can be formulated to a rate-dependent damage evolution law in a simple form for engineering application. The corresponding dynamic coefficients of C30 concrete are also obtained from impact experimental results. Because the parameter is less than 1，the damage evolution corresponds to an impact toughening process that coincides well with the dynamic experimental results for C30 concrete.

The O-cell pile testing(OPT) method is a new axial static load test of pile. Based on plastic law of pile lateral soil，a set of analytical equations of the loading-settlement curve for OPT are established by using load transfer method，in which pile lateral soil is simulated with bilinear load-transfer model and pile toe soil with trilinear load-transfer model. The method to get the parameter of the load-transfer function is discussed. The analytical equation verified by two history engineering cases can be used to describe the loading-settlement characteristic of OPT effectively.

Modified stress method is a way to calculate stabilized layer settlement of the composite pile foundation. The main fault of this method is that it is too difficult to determine the pile-soil stress ratio—n. The statistics of the rigid pile stress in the composite pile foundation show that the ultimate capacity of rigid piles is used for over 90% in the edge and the corner of the foundation and over 80% in the middle. Accordingly the supposed capacity of rigid pile is close to its ultimate capacity. Thus the pile-soil stress ratio can be identified easily. So the new method is called ultimate stress method. In addition，the error caused by the hypothesis is studied. And it is compared with the error caused by the modified stress method. Conclusions are drawn as the following：the settlement calculated by the modified stress method without considering piles adjacent to the soil is bigger than reality；but it is smaller by the new assumption. So the settlement calculated by the ultimate stress method is closer to reality.

The basic theories of layered charging and layered tamping and the influences of explosive specific charge on distribution of explosive rock blocks for medium and deep hole blasting are discussed. Meanwhile the blasting wave theory and swelling blasting gas theory are applied to analyze the influences of layered charging and layered tamping on the blasting effect for controlled blasting of medium and deep hole. The successful application in the second-stage project of Dayaowan demonstrates that layered charging and layered tamping reasonably can improve the structure of charges，increase the utilization efficiency of explosion energy and make the distribution of block size perfect and that the rationality of explosive specific charge must be considered adequately in the structure of layered charging and layered tamping for medium and deep hole blasting. The principles obtained are expected to be useful for layout of charges，improving distribution of energy，optimizing blasting design and improving blasting quality.

The cause，mechanism and tentative control measures of mine earthquake in fully mechanized top coal caving mining are studied by case analysis. Because the coal caving height is larger in fully mechanized top coal caving mining，thick and hard rock strata at higher position turn into the main key stratum，which have large movement and higher impact energy. These enhance the possibility and harmfulness of mine earthquake. The mine earthquake is caused by many factors such as main key stratum，great structure，inadequate subsidence of step-shape gob boundary overburden，fault activation，stress concentration and reduction of long-time strength of section pillar. The great area breaking movement of main key stratum causes great structure unstable and gravity potential energy to be released at a large-scale degree. The superimposition of gravity potential energy and impact energy turns into impact kinetic energy，which causes mine earthquake by the work to surrounding rock of gob. Based on the reasonable layout of mining，the control techniques，for example，reasonable leakage wind，building embedding high strong buffer bulkhead or ┬-entry bulkhead，separating strata grouting under the main key stratum to reduce the subsidence，grouting into the O-shaped space in the gob，should be studied by experiments.

By numerical stimulation the temperature distribution were obtained in block-stone embankment with block-stone in different thicknesses. The comparative analyses show that block-stone embankment has well active cooling effect on the railway foundation by raising the permafrost table and decreasing the permafrost temperature. For a certain construction environment and a certain construction design there is an optimal thickness of block stone which will freeze the foundation most strongly and raise the permafrost table maximally. The cause is the slope effect of embankment and the thickness of block-stone. When the block-stone is thin the air flow in embankment is weak and can not obtain great cooling ability；but when too thick the slope effect will cause multi-direction flow of air and weaken the cooling ability in winter and heat insulation effect in summer.

The 3D geological modeling is a committed step of underground space digitization. The results，using the method based on the borehole data and combining interaction of scholars，show that the method is effective. But there are two key issues. First，the modeling course is complicated and convoluted, second，the modeling speed when dealing massive data is relatively slow. The above two questions are analyzed. To the first question，the digital model of knowledge reasoning is set up，which adopted the space algebra method. The method，describing stratum interface information with surface patch through the interpolation of properties of space data，considered the embedment of geological knowledge into the model，and mitigated the interactions of the users. To the second question，the whole research area is divided into several sub-fields according to the stratigraphic lacuna. The search areas are dynamically set up using the method of projection of reference TIN and Lagrangian interpolation in that case when the sub-fields contains special geological property while using the method of projection of reference TIN in other cases. So the modeling efficiency can be improved. The stratum interface model，which has rigorously enforce geometry and topological relation，can be obtained through the proposed methods. This modeling method can deal with the magnanimity data more quickly and reduce user¢s intervention，and is useful for dealing with the disparity of space distributions because of the impact of space between boreholes and the stratigraphic lacuna are considered.

Crossing-river tunnel of Fuxingdong road in Shanghai City is the first twin-tube and double-layer tunnel in China. The full length of the project is 2 785 m and the outer diameter of tunnel lining structure is 11.22 m. Based on this tunnel，a 3D elastoplastic finite element model of twin-tube shield tunnel，which bears water pressure，was developed. The general software，Marc，is adopted to build the finite element model and simulate a 90 m long tunnel section，whose diameter is 11 m. Drucker-Prager material model is used as the strength criterion for soil. Soil mass in a same layer is considered as an isotropic body based on the geological condition that the soil is basically homogeneous，and is horizontal layered. In the modeling，water pressure is applied as load acting on the upper soil layer¢s surface of the model. Models simulating various circumstances with different tunnel distances are analyzed，on which the researches emphases the influence rules of subsequent tunnel to antecedent tunnel through analyzing the following indices：settlement of ground surface，axial force and moment of lining，soil pressure of lining and diameter deformation of different direction. Reasonable tunnel distance is drawn，which can be a reference to optimal design of similar projects. During the construction，the internal force of lining，soil pressure of lining and displacement of key issues of antecedent-building tunnel are monitored. To verify the validity of the finite element model，monitoring and computing results are compared and analyzed. The significant results obtained provide a better understanding of excavation process of twin-tube tunnel，and it is helpful in guiding future design and construction in similar conditions.

Assuming soil was undrained，the computing formulae of ground deformation induced by both bulkhead additive thrust and friction force between shield and soil were derived from the Mindlin solution in elastic mechanics. Formula of ground deformation induced by ground loss was offered. Combining the formulae of ground deformation induced by ground loss，bulkhead additive thrust，and the friction force between shield and soil，the formula of total ground deformation induced by shield tunneling was obtained. This method was applied to the construction phase. As shown in analytical calculation，the calculated results were in accordance with the field data. Longitudinal surface deformation induced by shield tunnel was assumed as a S-shaped curve. Surfaces on both sides hunched up at the axis of excavation face. During normal construction process，the friction force between shield and soil exhibited greater influence on surface deformation compared with bulkhead additive thrust.

The geological characteristics of discontinuity plane of Hongfeng doubled arch tunnel in Jinhua—Lishui—Wenzhou highway are investigated and analyzed to obtain the characteristic parameters. Based on discontinuity plane mapping theory and keyblock theory，the overbreak of doubled arch tunnel is forecasted by using the analytical discontinuity plane characteristic parameters. At the same time，the appearance probability and the location of overbreak block in doubled arch tunnel are forecasted. The result shows that the overbreak location of doubled arch tunnel is located mainly in the connection between tunnel and middle guide tunnel. Under the condition of good connectivity of discontinuity，a great quantity of overbreak on side wall may occur. The forecasting and in-situ excavation are contrasted，and the causes of overbreak are analyzed. The good coincidence of forecasting and excavation offers a theoretical basis for the excavation of doubled arch tunnel reasonably.

Free swelling ratio is an important index for identification and classification of expansive soil. In the process of its tests many artificial factors exist，and its scientific and reliability are widely doubted，so searching an adequate and applicable index with fewer artificial factors and representing the nature of expansive soil is of significance. A new kind of testing measure is introduced. That is relative free swelling ratio test. The relative free swelling ratio is defined as the ratio of the equilibrium sediment volume of 10 g oven-dried soil in distilled water to that in coal soil(or CCl4). The significance of the index and the testing measure are described. Relative free swelling ratio and physical and mechanical properties tests for expansive soil are conducted systematically. From the tests it is found out that when compared to free swelling ratio，relative free swelling ratio shows better correlation with cation exchange capacity，specific surface and montmorillonite content，so it is concluded that relative free swelling ratio is consistent with the index which exhibits the nature of expansive soil. The credence is compared with the indices suggested by specifications for highways including liquid limit，plastic index and standard moisture absorption water content and the results indicate that the former shows a higher credence and possesses more feasibility，meanwhile the correlations between the relative free swelling ratio and other indices are good，so these indices should be considered together for identification and classification of expansive soil.