Applied Mechanics and Materials Vols. 204-208

Abstract: In order to study the frost heave characteristics of the carbonated saline soil, we have selected the carbonated saline soil sample of Da-An area in western Jilin province as the research object and analyzed the influence to the frost heave rate caused by the temperature, water content, compaction degree of soil sample, salt content, etc by indoor physical, chemical test and frost heave test. The results show that: the frost heave rate increases with the moisture content; On the bases of the certain salinity and moisture content, the frost heave rate has a increasing trend along with the increased compaction degree, but also there is the best frost heave compaction degree; Temperature changes have a great impact on the soil frost heave rate, gradually reducing the temperature, the frost heave deformation of the saline soil sample increases gradually, when the temperature down to -10 °C, the deformation are stabile; The frost heave rate increases almost with the salt content, which is for that if the salt content is larger, then the soil sample freezing point is lower, so the frozen works will last for a longer time, also the eventually larger frost heave rate.

Abstract: Principle of calculation of water and earth pressures together by Limit Equilibrium Method (LEM) is introduced, and coupled deformation and seepage analysis is conducted by Finite Element Method (FEM ).The response of one soil slope is simulated during rapid drawdown of water level by LEM and FEM. The results calculated show that seepage upraises the critical slip surfaces, and critical slip surfaces and safety factors by two ways are pretty close. To assure the safety of the slope, the design of anti-slide piles is carried out. Those ways used may provide reference to engineering practice.

Abstract: To analyze refreezing state and permafrost table of the frozen ground for the Qinghai-Tibet DC Transmission Line Engineering, temperature monitoring tests of fine-grained frozen soil were carried out and the thawing depth of backfilled soil was measured in Wudaoliang region of the Tibetan Plateau. The ground temperature fluctuates over time, and the fluctuation characteristics are determined by soil properties, climate, depth and other factors. The seasonally thawed layer is in the shallow of undisturbed frozen ground and backfilled soil. The maximum thawing depth of backfilled soil was about 2.3m more than permafrost table of the undisturbed frozen ground. Soil near the foundation slab was keeping frozen state. The results show that the construction of frozen ground in cold season is helpful to refreeze and keep frozen state of the ground, and can provide a basis for stability analysis of the engineering foundation.

Abstract: Nanomaterials are of great importance to improving mudcake quality, reducing lost circulation, enhancing borehole stability, and protecting reservoir. Some nanomaterials, including nanometer plugging materials, nano-sized MMH drilling fluids, nanocomposite super-short fibers, water-based film-forming drilling fluids, nano-based drilling fluid, and so on, are introduced, and all of them have significantly influence on reservoir protection. As a result, the application of nanomaterials in the field of reservoir protection is very useful for maintaining borehole stability and protecting reservoir.

Abstract: It is a dip slope with mudstone and sandstone interbedded at the northward 363K National Highway NO.3. in Taiwan. The Figure 1 showed the slope sliding due to continuous heavy rain on August 19, 2010. This study analyses the slope stability by the finite element method of program PLAXIS-2D, and explores the suitability of various control engineering methods. It is named analysis before design with anchors in this study before September 2010. The aim is to search the original parameters of the ground by comparing a potential sliding surface with monitor data of site. Then countermeasure analyzes the impact based on the loss of anchor prestress and the row of piles set. From the results of analysis, sliding surface analysis and the data which was derived from the early monitor judgments are consistent. The ground anchor has been unable to achieve good stable slope effect for the slope sliding, due to heavy rains. However, the rows of pile construction significantly improved the stability of the slope.

Abstract: The particle composition, physical and mechanical properties of tailings silt in Zhuziqing tailings dam were tested by means of field survey and lab test. And the liquefaction potential of tailings silt in Zhuziqing tailings dam were investigated based on field-performance data using standard penetration test (SPT) and wave velocity test (WVT) methods. Results show that the liquefaction potential of tailings silt in Zhuziqing tailings dam can be evaluated by means of SPT and WVT. Results also show that there is almost non liquefaction at the places in Zhuziqing tailings dam where are under the seventh sub-dam, and there is serious liquefaction in the new sub-dam and deposited beach, which locate at the places above the eleventh sub-dam.

Abstract: Through simulating interaction between pile and foundation soil after establishing surface-surface contact element with finite element method and ANSYS software, the load resistance performance and ultimate strength of the ground anchor pile working for a workover derrick are achieved. In winter, frozen soil depth can be up to 2 meters in north china. When temperature rises in spring, the Polar grassland changes by three stages, namely, frozen, freeze thawing and melted. But for the large temperature difference between morning and evening, the state of the soil layer is extremely unstable which greatly affect the carrying capacity of anchor piles. This paper focuses on the melting influence of soil layer and the load resistance performance is studied. With a set of calculation parameter, the simulation result shows that the carrying capacity of anchor piles decreases 28% in melted state than freeze thawing.

Abstract: The traditional formula using for the calculation of Expressway on high embankment of the retaining wall and the earth pressure can not be very good practical. In order to accurately determine the soil pressure calculation of the complex retaining wall in construction stage for guaranteeing the engineering safety, the experiment study on soil pressure is done, and the study on soil pressure monitoring data is also done. Then the valuable conclusions are obtained to facilitate better practical guidance for construction.

Abstract: Kunming area is adjacent to Dianchi Lake. Peat soil with high water content and high compressibility is widely distributed, rheological properties is one of the most important engineering properties of peat soil. However, compared with the peat soils in the other areas, the peat soil in Kunming area has different properties. This paper studied rheological properties of peat soil in Kunming area by using the creep test of loading and unloading, on the basis of the strain-time curves, parting linear visco-elasticity, linear visco-plasticity and nonlinear visco-plasticity from the total deformation. Research shows that: ①The deformation is mostly composed of unrecoverable deformation and there is instantaneous elastic strain, instantaneous plastic strain in total strain; ②In low stress level,the soil is rendered as visco-elasticity. However, when the stress level is high, the performance of soil is visco-plasticity; ③By stress-strain curve clusters, yield stress of peat soil is approximate to 3.6 kPa in Kunming; ④Along with the time, modulus of linear visco-elasticity tended to be stable.

Abstract: Deformation modulus plays an important role in evaluating slope stability of rock mass and conducting the geotechnical engineering design. Based on the research of geological properties, physical and mechanical parameters of predominant rock mass types for different formations from Zhongxian to Wuhan, China, deformation modulus values of gas pipeline area were estimated by using rock mass classification method in this paper. Comparisons were made amongst different formulas based on GSI, RMR and Q methods to suggest range values of deformation modulus for predominant rock mass types of different formations which gives instructions to estimate strength parameters of rock masses for similar projects.