Advanced Materials Research Vols. 671-674

Abstract: North Uskyurt Basin, located on Turan Plain, northwestern Central Asian, is continental polycyclic cratonic. The structural evolution of the basin underwent six phases: basement formulation, passive edge, rifting, post-rifting, compression, early Neogene depression. Regional structural evolution takes control of complicated transition of North Uskyurt sedimentary structure. In general, basin sedimentary environment underwent basement (granite, metamorphic rocks) passive edge, late Devonian epoch carboniferous period (marine facies) rifting, late Permian epoch-triassic period (continental facies) post-rifting, Jurassic period-Cretaceous period (Marine-continental Transition Facies, marine facies) compression, late Eocene-Miocene epoch (marine-continental facies coexistence) Neogene depression, Pliocene-Holocene (continental facies). Consequently, sedimentary formation in which various sedimentary environment, such as marine facies, continental facies, are coexisted with various rock types, such as clastic rocks, carbonate rocks, is generated.

Abstract: Saturated Sand；Cyclic Loading；Dynamic Strength；Vibration Liquefaction Abstract.The liquefaction problem of saturated sand under cyclic loading is essentially a dynamic strength problems,but under the action of load,its strength has a sudden dramatic loss and it is unexpected.so it is different from the general dynamic strength problem.This paper analyzes the dynamic strength of saturated sand under cyclic loading.And its vibration liquefaction mechanism, influencing factors and preventive measures are analyzed and discussed.

Abstract: Many methods have been used for slope stability analysis in recent years. Limit equilibrium method is more popular than others, but its model is very simple. This paper gives a more reasonable model and develops a program by VC++ . A reasonable result is obtained with the proposed model.

Abstract: The cone dynamic penetration test is a kind of test method, which has the features of simple device, easy operation, great adaptability, high efficiency and it also is a continuous in-situ test method. But in the common geotechnical exploration activities, we found that bearing capacity of foundation is always larger than the measured value, by analysis to the blow count of cone dynamic penetration in the standard table. This article set the gravel soil geotechnical exploration of Guangxi province’s city planning exhibition center of China as the example, to start with the theory of cone dynamic penetration, and analysis the reason why there are the abnormal value in the dynamic penetration, furthermore, provide the relative error correction models for it. Finally, establish the rational relationship between dynamic penetration results and foundation soil mechanical parameters.

Abstract: Deformation is the macroscopic index for the structure of geotechnical engineering, it is important for the design and construction of geotechnical engineering to monitor the deformation and analyze the monitored data. Kalman filter can enhance the effectiveness of the monitored data and wavelet neural network has the favorable time－frequency localization features and self－learning function. Firstly, the monitored data has been filtered by Kalman filter, and then a deformation forecast model will be established by means of combining with neural network wavelet to predict the deformation of actual engineering. The result shows that the forecast model is successful and effective to forecast the slope deformation.

Abstract: Based on the core, thin section, scanning electron microscopy, well logging and the physical properties of reservoir, according to the research on the volcanic reservoirs characteristics of the E2-3S3 Formation in Oulituozi area, obtaining the following points: Basalt, trachyte and tuff are mainly lithology, overflow facies are main lithofacies, secondly explosive facies and volcanic sedimentary facies; Secondary reservoir spaces are often superimposed on the original reservoir spaces, and pore, hole and slit together form the effective reservoir spaces; The reservoir property show that the trachyte are the best, secondly the basalt and tuff; Reservoir lithology, lithofacies, thickness, fracture development, physical and electrical properties and other reservoir parameters are the main evaluation criteria to conduct the reservoir comprehensive evaluation.

Abstract: Three numerical sample preparation methods, namely, radius expand method, hierarchical compaction method and gravity descent method, were studied using discrete element method (DEM) to simulate the actual sample. The processes of these three methods were described in details and the differences of these three methods were discussed. The impacts of mechanical parameters in DEM model on the numerical results were analyzed.

Abstract: The excavation roadbed was used in K29+450～900 sections of secondary highway from Gengma to Qingshui River. The design roadbed width was 12m, and after an excavation, the inclination of side slope was between 27 to 50 °. It is Nanting River below bed and the vertical distance is 20m between them. Under actions of external load, mountain slipping and river scouring, there appears an instable phenomenon in slope. The pile board wall had inclined which is located in the central section of one side of roadbed and close to K29+900 section after construction. The inclining range was larger and the inclination that was serious at pile head at the top reached about 2m. The research was focused on a side slope engineering in K29+450~900 sections and through site survey, the topography and geological features of slope were known and mastered. By drilling, high-density electric method and numerical simulation method, the depth and scope of slip surface were determined to provide a basis for governance programme of engineering reinforcement.

Abstract: Structure characteristic is the essential property of natural soils. The paper developed an indoor method of artificial structural loess, and studied on the true triaxial tests of artificial structural loess on the base of improving the original true triaxial apparatus. The results show that it is reasonably reliable of this artificial method. At the same time, the variation of failure strength and residual strength of structural loess under complex stress conditions was analysised. When the confining pressure was less than the structural strength of the structural loess, the stress-strain curve was soften, on the contrary the stress-strain curve was harden. In the end the paper analyzed that Mohr-Coulomb strength criterion was accurately to describe the residual strength variation of structural loess but there has much error in describing the peak broken strength, the value was obviously small.

Abstract: This paper presents the finite element analysis of the model pile loading test considering large deformation theory. The area around pile tip is concentrated with significant compressive and shear stresses. A constitutive model with particle crushing is adopted to describe the mechanical behavior of model ground. The jointed element is introduced in numerical analysis to simulate the interaction between pile and its surrounding soil. The predictions of the relationship between the normalized bearing stress and displacement are good agreeable with the test results. The influences of the joint element on the accuracy of the predicted values are obtained. The figures of distribution for displacement vectors with different penetration depth are shown and discussed.