The result of triaxial test shows that soft rock has notable strain softening characteristic, and the stress-strain curves present different types in the normally consolidated field and over-consolidated field. In normal consolidated field the softening degree of soft rock is slight relatively; but in over consolidated field, when axial stress comes to peak value, the softening speed increases rapidly with the increasing of strain. In order to simulate the stress-strain curves of this soft rock, the constitutive equation of consolidated undrained triaxial stress state expressed in strain space is deduced. This constitutive equation is used to simulate the stress-strain curves of soft rock, and in simulation different hardening functions, including a new proposed one, are applied. The simulation result shows good agreement with test result. It demonstrates that constitutive model established in strain space has good ability to describe the strain softening; and the new hardening function shows good applicability for normal consolidated soft rock under consolidated undrained state.

Plane strain state is familiar in geotechnical engineering, and estimating the principal stress in the plane strain state is very complicated. Based on the results of constant stress ratio plane strain tests, an interesting conclusion is drawn that the principal stress in the direction in which the principal strain keeps zero may be major principal stress, intermediate principal stress or minor principal stress. By using the tangent Poisson’s ratio obtained from constant stress ratio triaxial compression tests, the behavior that the principal stress in zero strain direction transforms in constant stress ratio plane strain tests could be predicted. This conclusion is meaningful for analyzing some problems during engineering practice.

Many slope stability studies have indicated that the infiltration of rainfall into a slope decreases its stability. And some of its mechanism has becoming understood. However, it remains an unresolved problem how to quantify the percentage of the rainfall infiltrating into a slope during a rainstorm. The model proposed by Holten on how to calculate the rainfall infiltration into a slope does not meet the precision requirements in practice. And most numerical models cannot simulate the true infiltration progress. Based on self-designed soil column tests, the process of rainfall infiltration has been studied. The results elucidate the mechanism of rainfall infiltration. An improved method for calculating the percent rainfall infiltration is proposed. A numerical model is used to shed further light on the rainfall infiltration mechanism not obtainable from the indoor laboratory experiments.

By a near-symmetric matrix, we mean that only a very few of entries in the matrix are non-symmetric. If those non-symmetric entries above the diagonal are replaced with the corresponding entries below the diagonal, it will become symmetric. Such a matrix can be encountered in the analysis of nonlinear continuum problems. Based on Sherman-Morrison’s formula, a new scheme for decomposing near-symmetric matrices is proposed, which is much more effective and less memory-used than those solvers for common sparse non-symmetric matrices under the condition that the numerical stability is assured. Moreover, the solver corresponding to the scheme, which is suitable for both symmetric and non-symmetric matrices, can be developed through slightly augmenting the solvers based on LDLT decomposition. With an example on a frictional contact problem, the advantages of the proposed scheme are illustrated.

A series of centrifuge tests were performed to investigate the behavior of copper ionic migration in unsaturated cohesive soils. From this study, it is indicated that the hydraulic driven flow controlled the migration of copper ions in soils during the period of the first year. The contaminant region changes from a triangular shape in the first year to a more square like later. Vertical movement is more significant than horizontal. Compaction is a very practical method to reduce the hydraulic conductivity of the soil and thus to retard the movement of contaminants. It was demonstrated effective by centrifuge tests. Minor difference of clay content in natural soils will result in significant difference on copper ionic migration. When mixed with bentonite, this barrier effect of clay was enhanced.

The compression tests are conducted on Lanzhou and Xi’an intact loess under different water contents. The quantitative comprehensive structural parameter is defined by using void ratio of intact, disturbed and saturated loess. The effects of water content and pressure on the structural parameter are investigated. The study indicates. (1) The better relationship between deformation characteristics (compressibility and collapsibility) and structure can be obtained by using the variation characteristics of the structural parameter of intact loess with the change of water content and pressure. (2) Under the same water content, the structure parameter increases with the increase of pressure before structure strength; and it decreases or scarcely increases after it. (3) Under the same pressure, the structure parameter scarcely decreases with the increase of water content before the initial structure destruction water content ?f; and it apparently decreases after it. ?f decreases with the increase of pressure. The change of water content has obvious effect on the structure parameter.(4) The relationship between coefficient of collapsibility and the structural parameter almost is the same line for intact loess in two regions under different pressures and water contents.

The concept of depth limit for the method applied to sinking of shaft lining by means of floatation in shaft boring that is widely utilized in mine construction in China was put forward. The mechanical state of shaft lining filled part of water when its pan touching the base rock of shaft bottom was analyzed. Contacting with the technical characteristic of shaft lining sinking by means of floatation, the calculation model of shaft lining filled part of water in mud before fixed, as a self-gravitating bar in liquid, was set-up. Based on energy methods as well as the principle of structural stability theory and hydromechanics theory, the analytical equation for vertical structure stability critical height of shaft cylinder filled part of water was calculated. A typical example was persuasively analyzed. The attention to use the equation was emphasized in shaft design and its construction. Finally, its further research contents and direction are pointed out.

Based on the algorithm advised by Abdallah I. Husein and his classmates, some improvements have been made as follows: (1) adding several conditions of geometry rationality; (2) developing a technique by controlling the range of slip segments rotation to prevent two adjacent vertices of a slip surface from approaching each other; (3) making the algorithm to be suitable for slip surfaces that are convex upward; (4) adding the changeable vertex count mechanism of a slip surface during the searching procedure in order to make the critical slip surface more smooth. The results show that the modified algorithm is more practical feasibility and stability to aim at searching the critical slip surface, preserving the advantages of the original algorithm. The algorithm is also adopted by the slope stability analysis software named ZSlope developed by the authors.

Using the FLAC algorithm based on Lagrangian explicit finite difference method, numerical analyses are made on ultimate bearing capacity and failure behavior of strip footings and circular footings founded on nonhomogeneous clays foundations in which soil cohesion increases linearly with depth. Numerical results show that: (1) foundation failure area much more centralizes in surface layer and around footing sides as nonhomogeneous factor kB/c0 increases; (2) bearing capacity are estimated very conservatively if foundation nonhomogeneity is ignored even if kB/c0 is low; (3) bearing capacity factor of footing nonlinearly increases with kB/c0 and interface characteristic of footing and soil has less influence on the bearing capacity shape factor of circular footings except for the homogeneous foundation. Compared with numerical results, it is found that the approximate equations of Skempton and Peck et al. obviously overestimate bearing capacity factor Nc0 for nonhomogeneous soils.

Analytic soulution and illustration of elastic energy releasing amount of rock dynamic destabilization is given for the first time by the step of Ⅱ body in the form of precise and approximate catastrophe model. It is advanced from qualitative understand to quantitative description that study on rock stability on the stage before and after the period of earthquake and rockburst. The end of rock dynamic destabilization is confirmed strictly, and scientific basis is offered for the calculation on earthquake efficiency, for the study on earthquake energy scale released, earthquake stress fall, fault offset after earthquake and recovery amount of surrounding rock elastic strain. The system will possess ability to apply work to surroundings when it destabilizes, and earthquake wave energy is the matter that destabilizing rock system applies work to surroundings in the devastating way. Information implicated in illustration of elastic energy releasing in paper, produces credible evidence for confirming that the mathematical model of rock dynamic destabilization is fold catastrophe model.

The foamed beads light soil is a new soil materials with the features of lightweight and high strength; it can be used for road base, bridge and other construction applications widely. In order to evaluate the engineering properties of foamed beads light soil, the strength and deformation properties of foamed beads light soil are analyzed based on laboratory tests and analytical method. Based on the results, the double-phase model is utilized to evaluate the stress-strain properties of foamed beads light soil. By this analytical method, it will be helpful to evaluate the influences of caring time, light filling volume ratio on strength and deformation properties of foamed beads light soil. Thereby, the results will be useful for the application of foamed beads light soil in future.

In accordance with the random vibration theory, the statistical probabilistic characteristics about the maximum displacement response between layers of parallel base isolated structure, are analyzed; the calculating formula of displacement mean value and standard variation value are derived. With a 4-story parallel base isolated RC frame chosen as numerical example，the results of the mean and standard variation responses of the maximum inter-story drift are gained. It indicates that the maximum displacement mean value of the isolation layer will reduce if the fundamental frequency ratio of base isolation system to the fixed base system and the yielding force of the isolation layer are increased.

The traditional theory of soil mechanics considered that the preconsolidation of soil was controlled by the pressure force and stress history. However, based on the experimental results, the rule of the preconsolidation of red clay that is territorial peculiar soil is different from the traditional theory. The studies show that, the preconsolidation of red clay is most constrained by soil genesis, structure and component, and is affected by the overlying pressure in little degree. Finally, the defect of traditional soil mechanical view on red clay is analyzed; and the genuine signification of preconsolidation pressure of red clay was studied; and the new understanding about the preconsolidation is presented.

The simulation of stage excavation of the stratified rock slope of Chang-Zhang expressway is carried out by using our own two-dimensional elastoplastic finite element program, in consideration of the influence of blasting and rock joint. The rock-mass’s deformation, stresses and yielding state in the excavation process are analyzed respectively. The integral safety of the high slope for every stage excavation is discussed by using the method of lowing material’s strength safety factor. The results show that the slope is stable in construction process.

The improvement of expansive soil is an important lesson in the study of expansive soil subgrade treatment; so it has been concerned by the geotechnical researchers and engineers. Combined with slope treatment project of expansive soil on a highway, the chemical improving expansive soil by experiment with ESR ecotypic medicine is studied. Both of the mechanism and the effectiveness of improving expansive soil are analysed. It is discovered that the expansive soil become non-expansive after chemical treatment. The improved expansive soil has been changed from hydrophilicity to hydrophobicity and has good water stability. While the soil has the characteristic of sand and every strength index is largely increased. The foundation bearing capacity is also increased by the number of spraying; and the best spraying number is 3－4.

Taking the unsaturated loess at Yangling in Shaanxi Province as the research object, the compressive tests on different stress paths are made with the intact loess and the corresponding remoulded loess under different water contents. The comprehensive structure potential parameters of unsaturated loess are calculated under different stress conditions. Based on the above, the variation characteristics of structural loess are studied under equal stress ratio condition. The result indicates: when the water content is invariable, the stress ratio(?=?3/?1)influences the structural characteristics of intact loess obviously; the performance is smaller for the stress ratio; the structural characteristics of intact loess is weaker; when the stress ratio is invariable, the water content of intact loess influences the structural parameter obviously. The lower water content, the bigger structural parameter. Especially in the region of low water content, the structural characteristics of unsaturated loess are influenced by the variation of water content strongly.

Free swell is one of indexes in representing the expansibility of clayey soil and makes great valuable reference in the judgment of expansive soil. Free swell test is commonly used in China to obtain the swell-shrinking property of clay due to its simple equipments and easy operation. But, the deficiencies of standard for soil test method and trade specification exit in the regulation and explanation of the details for free swell test, that leads to the great difference in the test results when totally operating according to methods in the standards and specifications for the same soil sample. In order to make free swell test more complete and test result more stable, two main artificial factors related to test result are discussed and analyzed and some suggestions for improving the current standards and specifications are given.

Through analyzing the present rheological models and experimenting lots of creeping tests of frozen clay specimens under uniaxial stress states, the results show that the nonlinear N element substitute for the linear one is feasible and the Xiyuan model is improved. Making use of the Mises yield criterion, a soft matrix is derived to use numerical calculating as a viscous-elastic-plastic material. Numerical simulation of the shaft well excavation process and field measurements of the deformation of deep soil frozen wall in Huainan Mine show that the improved Nishihara model is feasible for FEM numerical simulation of deep soil frozen wall.

The morphology of sandstone fracture main crack and subcritical fracture crack (that growth due to stress concentration but not turn into fracture main crack) in mesoscale level have been systematically investigated through the three-point bending fracture test with scanning electron microscope (SEM). It is shown that the fracture of sandstone behaved complicatedly, and correlated with not only the composition of sandstone binding material but also the distribution of sandstone fragmentary particle. Furthermore, there give birth to many subcritical fracture cracks in the fracture process. The morphology of fracture main crack and subcritical fracture crack is similar. Ductile fracture has been taken place if the specimen has many subcritical fracture cracks in the fracture process zone. Contrary that brittle fracture will be taken place.

The depth of soil layer which influenced by climate in Hefei is studied by way of climate environmental data and field experiment of water content. It can be found that the calculated depth of the layer according to climate environmental data is smaller than the real value. On this foundation, the determination method of treatment depth for subgrade paved with expansive soil is proposed based on the relationship of swelling pressure and unloaded expansibility. The correlative curve of the expansive pressure and the unloaded expansibility is established by means of swelling pressure test of eighteen representative soils selected from Hefei. It provides reliable references for determining the treatment depth of subgrade. Finally, some suggestions of treatment depth for the different structure positions of subgrade are given.

Dam body, dam foundation and surrounding environment constitute a complicated system. Dam behavior is influenced by geological factors and engineering factors. Some of above factors are determinate, others are stochastic, fuzzy and alterable. It is a decision-making problem of engineering system to assess dam behavior. Qualitative knowledge and quantitative data need to be integrated. Quantitative change and qualitative change all need be reflected in the assessment results of dam behavior. The behavior of whole dam system need also be assessed by combination of different items. A method integrating quantitative and qualitative information need be used to assess dam behavior. Extension theory is used generally to solve the inconsistent problems. A matter element consisted of research object, evaluation index, normalized value. According to rhombic thinking mode and the extension of matter element, the multi-index and hierarchical system of dam behavior evaluation was built. Matter-element model was constructed to assess dam behavior by matter-element transform. Three-dimensional evaluation for the behavior of whole dam system can be implemented by quantitative, qualitative description and their change with time. The proposed principle is also used to assess the global stability of rock slope, rock quality and dam aging.

An adsorption potential function produced by the interaction between gas and solid skelecton is introduced and regarded as a factor for the stress and deformation of the solid skeleton especially for the swelling of the coal. A general form of the thermoelastic constitutive model of coal is given considering the adsorption of CO2. After the thermodynamic analysis of the constitutive relation, it is found that the adsorption potential affects the stress and deformation indirectly through remodeling the form of the heat transfer equation and changing the thermodynamic restriction condition. But it doesn’t change the form of stress-strain relation. A constitutive model can be built the moment that the free energy function and adsorption potential are given.

Shell embankment is a naturally formed special type of coastal bank. The embankment consisting a mixture of shell and sand possesses the properties of high permeability, large sensitivity, poor anti-weathering capacity and lower stability. To construct the profile, the following aspects have been considered: (1) Safe excavation; (2) satisfying the requirement of anti- earthquake and (3) better exhibition effect. Based on the results of theoretical analysis and experiment, the chemical grouting technique is adopted. The excavation of the profile of the shell embankment has been safely carried out. The stability of the constructed profile of the shell embankment is then tested by the standard dynamic penetration tests. The finite element analysis is also performed to prove the short term and long term stability. Aseismic analysis is also performed to assess the aseismic capability of the exhibiting profile of the shell embankment.

The time effect of soil deformation reflects the unification of soil consolidation and rheology, and that is, the soil rigidity itself has time effect. Through the analytical method, the rigidity matrix of building foundation considering time effect has been established; and thus the calculation of the rigid foundation is solved with program. The working mechanism of the rigid foundation, such as the contact pressure and deformation, has been demonstrated. Initially, the settlement and contact pressure of the foundation develop quickly in the beginning of loading, and then slow down. Along with the time growth, the settlement still increases, also, the contact pressure increases in the corner of foundation and decreases in the center, and gradually tends to be stable. Finally, the distribution curve of the counterforce acting on foundation is characteristic of a saddle-like shape, which is higher in the edges and lower in the center.

The formulation and evolution of blast-induced cracks in rock are simulated by .ANSYS/LS-DYNA programs. Based on dynamical characteristics of hornstone and Von Mises failure criteria of rock-like materials, the sizes of crushing zone and fracture area are obtained. The mechanism of crack formulation in rock blasting is also analyzed; and attenuation characteristics of maximum pressure are also given. It is found that the radius of crushing zone in rock is approximately 6.5 times of the cylindrical charge, while the radius of fracture area is approximately 75 times of the cylindrical charge. The crushing zone forming process is rapid, lasting nearly 80 μs, but the fracturing zone process host long time. After crushing zone formed, tangential fractures will appear around.

The computing formulas of superimposed load on adjacent level parallel pipe induced both by bulkhead additive thrust, force of friction between shield and soil, and force of friction between follow-up pipes and soil are derived from the Mindlin solution in elastic mechanics. The influences of pipe net spacing distance, pipe diameter, buried depth and soil’s Poisson ratio on the distribution of superimposed load are discussed. The analytical results show that the pressure on adjacent level parallel pipe induced by force of friction between follow-up pipes and soil is small during injecting slurry; and the peak value appears at the back of excavation face. When construction is in normal, superimposed load induced by bulkhead additive thrust is very small. For adjacent level parallel pipes, pressure is produced in front of excavation face while pull force at the back. They distributed antisymmetrically with the axes of excavation face. Superimposed load induced by force of friction between shield and soil and is much larger than that of bulkhead additive thrust with its “zero point” at the middle of shield. The force of friction between shield and soil plays a leading role, thus, it should be considered highly during construction.

Based on unified strength theory, considering condition of plane style of rock mass with discontinuous plane, the unified strength formulation for strength of rock mass with single joint, i.e. failure criterion of rock mass of considering the intermediate principal stress, is derived by introducing unified strength parameters ct and φt of material; and the effective range of formulation is analyzed. The proposed formulation is verified by triaxial experiments of diatomaceous soft rock and gypsum; and the change of strength of rock mass with the variation of parameter b of intermediate principal shear stress is analyzed; and the results show that the strength increases with the increasing of parameter b. The parameters ct and φt are calculated and analyzed in term of determination method of parameters ct and φt of geomaterial; and note that they change with parameter b.

One of the measures of actively and forwardly protecting frozen soil is adjusting the temperature of embankment by ripped-rock layer, used in the railway design in permafrost regions. The effect of adjusting temperature consists of heat shield during summer-time and convective cooling during winter-time. In this study, a preliminary analysis was given to the thermal regime of ground temperature under the ripped-rock layer with both different grain diameters based on the in-situ measured data. The result showed that during summer-time, the ripped-rock layer with a grain diameter of 50－80 mm had better heat barrier than that one of 400－500 mm, but during winter-time, the latter had stronger convective cooling action. By a cyclic contrast, it was still found that the latter was excess to the former in the adjusting temperature. Moreover, the mostly part of 0℃ isotherm has closed to the natural ground surface when the foundation soil under the revetment reaches the maximum of thawed depth; this will be benefit to the thermal stability of embankment.

Because of the complexity and variety of geotechnical material, the rheology constitutive models put forward by existing FEM software can’t usually satisfy the requirement of actual numerical analysis. In accordance with fundamental code-run-principle of FLAC3D Version 2.1 software, the basic principle of the secondary development program running is made, and detailed analysis combined with the Nishihara viscoelasto-plastic rheological model is given. The program flow diagram on the special execution of Nishihara rheological model and several case technique that should be taken into account in the process of code compiling is given. At the same time, an easy case is used to verify the right and credibility of program compiling. The Secondary development environment is more friendly and effective with the support of object-oriented approach. Therefore, proposed design mode can bring forward references for the secondary development of other rheological models.

A new approach to recognize critical slip surface is proposed by combining the support vector machine and genetic algorithm.The learning and testing samples produced in orthogonal experiment are used to train the support vector machine. Thus, the support vector machine is used to describe the relationship between slip surface and factor of safety. Then genetic algorithm is adopted to search critical slip surface in their global ranges. This approach was applied to two examples. The results are satisfactory.

Based on the non-circular failure surface analysis method for the calculation of integral stability of slope, an improved genetic algorithm is presented; it can freely search for the most dangerous failure surface of slope and corresponding minimum safety factor without supposing the geometric shape of the most dangerous failure surface. The analytical results of some slopes by the proposed method and the comparisons between the proposed method and other ones show that the proposed method is accurate，reliable and able to find out the global optimal solution. At the same time, the underground vacant areas are the primary factors, if the other conditions are invariable.

Aiming at special method of installation of rammed soil-cement piles, a new type of strain transducer in pile was proposed. And then, based on loading test data of rammed soil-cement single piles, load transfer behavior of rammed soil-cement piles and distribution of shaft resistance in single pile are studied. Results show that transmission of loads along pile are limited to a certain range at the shallow depth due to limited strength of rammed soil-cement pile. The deformation, axial load, distribution of shaft resistance occurred mainly within this range; and the varying gradient of every variable is larger.

After the basic theory of Asaoka’s method is systematically introduced, the relevant calculation program is written based on parabola interpolation method and linear least squares simulation method. Then, detailed analyses of the effect of time interval ?t on predicted results and related indexes are done, and the suggested scope of ?t is given. Besides, the final settlements of each level loading for an embankment subjected to multi-loadings are forecasted. It is observed that the parabola interpolation method in the calculation code is feasible and Asaoka’s method has higher application value due to its own characteristics.

Skin friction of pile mainly depends on mechanical characteristics of surrounding soils, relative displacement on interface, lateral effective pressure, behavior of pile-soil interface, time effect, etc.. Based on the analysis of hyperbolic model of skin friction, the in-situ static test results of cast-in-place piles conducted in some places of Shanghai, are analyzed. Ranges of computational parameters related to hyperbolic model of skin friction are given. In addition, time-effect of skin friction of piles is also discussed briefly. Results show that it’s rational to illustrate the relationship between skin friction and relative displacement by hyperbolic function. In addition, due to time effect of pile displacement, lateral skin friction of pile indicates evident time-dependence.

On the assumption that any part of displacement of anti-float anchor is linear elastic relation, the relations about frictional resistance, axial force and displacement between soil and bolt can be derived by applying the mechanics theory. The example shows that based on the linear elastic analysis model, the formulas of frictional resistance, axial force and displacement can describe the elastic stress and strain better. The distribution of frictional resistance and shear displacement along the anti- float anchoring length are obtained. It comfirms that the shear displacement between the bolt and surrounding soil is main displacement for the bolts buried in soil.

Based on the variational principle of potential energy, displacement jump condition which depends only on material strength is derived. Moreover, the connection of displacement jump and uniqueness of governing equations is built; and equivalent scopes are verified. Uniqueness of governing equations uses constitutive/acoustic tensor to deal with material stable problem caused by stiffness degeneration, which could be equal to displacement jump condition; but it is less straightforward than the displacement jump condition described by material strength, especially, those materials whose strength can be tested easily at lab.

A model of multistage fuzzy comprehensive evaluation for unloading high-steep slope stability analysis has been established. Based on the detailed geologic survey of the unloading high-steep slope of a hydropower station, a fuzzy comprehensive evaluation has been carried out by using the established model to estimate the stability of unloading high-steep slope; the estimated results had veritably reflected the steady state of the slope. The example shows that the application of this model for stability analysis of unloading high-steep slope is feasible.

The claystones of the upper Tertiary Luoyang Formation has widespread distribution at the foundation of the Xixiayuan Project hydroelectric power station on the Yellow River. The field surveys reveal that the claystones have specific engineering geological characteristics, mainly found to exhibit weather and disintegration within a short period of time when exposed to the atmosphere or moistened, and the rock properties often change to properties with more characteristics of soil during excavation. In order to gain better understanding about the claystone of Luoyang Formation, a series of experimental laboratory studies were carried out involving in-situ large scale shear test. For some samples tested in this study, the clay mineral component of the claystone is high with maximum 53.7 % which have a mount of smectite with a range of 28 %－38 %, the swelling ratio 0.6 %－4.9%, the axial compressive strength 0.11－1.04 MPa, the shear strength (kPa). The claystone of the Luoyang Formation has properties of hard soil-soft rock.

Chaoyang slope is a typical landslide, which is composed of gentle inclined argillaceous sandstone. By investigation of the slope, its engineering geologic conditions, buried weak layers, gullies’ relationships, strength parameters and the development of fractures are acquired and analyzed. Based on the knowledge of landslides of red sandstones, residents on it can remove to safety place before the onset of the landslide; and then heavy accident can be avoided. The intrinsic factors of red sandstones’ landslides are buried weak layers and the formation of their free faces; and the external course is the decrease of shear strength due to the heavy rainfalls. Chaoyang slope is a good example of landslides; and its analyses should be useful for any workers related to landslides.

Observations of pore water pressure, settlement and lateral displacement were carried out and consolidation coefficient and consolidation degree were calculated based on the observed data in a foundation treatment with prefabricated strip drains at a seaside ground. The results of static penetration test, vane shear test, standard penetration test and plate load test after consolidation indicated reinforcements of foundation and increases of stabilization in 50 days. It is shown that the reinforcing foundation with prefabricated strip drains is an effective measure at seaside ground.

According to the Xiedipo double-arch tunnel engineering of the Yishui(Yibin—Shuifu) Highway, the key parts of structure force are monitored and analyzed by setting testing component in the tunnel; and during each period of construction the stress state of surrounding rock, bolt axial force, internal force of the middle-wall and internal forces of tunnel supporting structure are obtained under the condition of the constructional partial press. By analyzing tunnel mechanical characteristic under constructional partial press, the conclusions are drawn as follows: the most dangerous construction procedure of the tunnel structure force is from one side to the other side in the construction of the tunnel, that the bending moment direction of the middle-wall is always from one tunnel constructed lastly to the other tunnel constructed firstly in the double-arch tunnel. The monitored data and the experience can be for reference in the design, construction and research of similar tunnels.

Based on the geologic data of a existing expressway，for its widening engineering，the improvement effect of new and old road foundations with different improvement methods is simulated numerically by popular FEM program. Result shows that the loading of new embankment will induce the instant deformation of old road to some extent; and the new road foundation with composite foundation method will produce less differential settlement; and the consolidation degree of old road foundation before constructing new one has less effect on the improvement effect of composite foundation method.

For up bamboo-truncating tunnel portal without obvious wall-style structure, there is no existent design method and structure checked mode in present code. In this paper, aiming at bored method and open-cut method for portal section, 3D FEM numerical analysis method is adopted to study the mechanical behaviors and design method of tunnel portal section. The research results show that: Choosing 42 m as the length of portal section and designing as a whole could be reasonable; In the shallow burying section of the extension of 28 m, the surrounding rock pressure of lining crown increases with the increase of depth of tunnel; and pressure of the bored tunneling method tunnel is maximal, the calculation result following the method of the railway tunnel code is the second; and the pressure of the open-cut method is minimal; When taking open-cut method, in the longitudinal direction of the extension of 42 m of portal, the mechanical behaviors of lining crown shows some characters of stringer bending, part of crown is in bended-pulled state; the internal force shows a three-dimensional effect, and the internal force of the direction both transversal and longitudinal should be checked for structure; when taking bored method, the internal force checking is only considered for transversal direction; when the excavation condition allows, the bored method is suggested to do portal tunneling by the reason that this tunneling method can improve mechanical behaviors of tunnel portal structure effectively.

The mechanical properties of argil fly-ash concrete and effectiveness of its application to abutment-backfill are investigated by material experiment, centrifugal modeling test and numerical calculation. It is pointed that the properties of argil fly-ash concrete are superior to that of other backfill materials. Its properties have the advantages of light mass, high strength and high modulus. In addition, its construction method is different to that of other materials. Its soil pressure and settlement are smaller than that of other materials markedly. Consequently, the results indicate that the argil fly-ash concrete is recommendable backfill material.

Salt dissolving of saline soil is harmful to construction. It is important to effectively treat saline soil. With the example of saline soil ground treatment of airfield in Northwest China, test of the soaking and dissolving, test of dynamic compaction for saline soil treatment are studied. The project is successfully constructed in accordance with technical requirement. The result of stabilization is well acquired according to checking.