Applied Mechanics and Materials Vols. 90-93

Abstract: At present, there are numerous treatment schemes for slope, while there is a lack of research on scheme evaluation and optimization. According to analytic hierarchy process, this paper takes two treatment schemes for Cangshang pit slope as research object, which are reducing load by cutting slope and strengthening by grouting, handles the complicated problem hierarchically and systematically, and establishes hierarchical structure model. Judgment matrixes are constructed to analyze multiple factors synthetically, which combine qualitative analysis and quantitative analysis preferably, and optimal scheme is selected finally.

Abstract: Based on the project of Baihetan hydropower station, concerning the extensively developed columnar joints rock within the dam site area, the article carries out a study on the asymmetric characteristic of stress distribution in a tilted transversely isotropic rock stratum, at presence of inclined structural interfaces, which is subjected to a strip loading. Several theories related to stress distribution of tilted transversely isotropic rock are analyzed, a numerical simulation of rock stratum is subsequently conducted and graphics of stress distribution corresponding to different inclination angle of structural interfaces are obtained. Finally, the paper makes a comparison between the stress distribution procured by simulation and that of the analytical theory, and a conclusion on how inclined structural interfaces influence mechanical properties of transversely isotropic rock is generalized.

Abstract: The study is still few for the slopes of rock with low permeation，which has interfaces for rain infiltration and no interface for effusion. The stability of slope with rainfall infiltrating under different drain condition is evaluated by the global safety factor, based on the limited equilibrium methods. The following conclusions are obtained: (1) the two rows of drains don’t enhance the value of safety factor very much, and the layout of only one row of drains is advocated；(2) the effect of the system in which drains beat in marlite is better than the system in which drains beat in the breccia；(3) the effect of the system in which drains are designed in the toe of the slope is best, and the spacing of the drains whose diameter is 0.11 m should be less the 8m .

Abstract: The increase in pile bearing capacity with time after installation is known as soil/pile set-up. A mechanism of pile set-up is discussed in detail and a three-phase model is suggested. A serious of low-strain dynamic tests on full scale pile was carried out in mixed soil for monitoring the increase of wave velocity and stiffness. Wave velocity and stiffness have similar increase trend, but the stiffness shows a larger increase rate. An optimized design procedure to incorporate the pile set-up effects is proposed.

Abstract: The silt has the properties, such as low strength and slow drainage; so it is usually treated by precompression method. For short construction period and low cost , a new drained consolidation method-drainage consolidation due to excessive pore water pressure for silt is tested: fist, the sand is replaced in the surface of silt for horizontal drain; and then, the plastic drain boards is applied for vertical drain; finally, the excess pore water pressure is generated by surcharge loads and dynamic consolidation and the drainage consolidation is fast under the excess pore water pressure. The result of the settlement observation and acceptance test shows that the result of drainage consolidation due to excessive pore water pressure for silt soft soil is remarkable.

Abstract: Different reasons leaded to highway circuitous between plateau mountainous area and plain lightly undulate area were analyzed. The main reason which leaded to highway circuitous is the RDLS was concluded. The regression model between the RDLS and calibration coefficient of different technological levels of highway in plateau mountainous area was acquired by the least square method and the statistical tests based on the RDLS and calibration coefficient basic data. Taken Yunnan Province which is mountainous plateau province for example, the regression model between the RDLS and calibration coefficient was acquired, using the RDLS and Calibration coefficient basic date form all technological levels of highway in Yunnan Province of different elevation plateau mountainous areas.

Abstract: On the basis of coulomb’s concept that the active earth pressure against the back of a retaining wall is due to the thrust force exerted by a sliding wedge of soil between the back of the wall and a plane which passes through the bottom edge of the wall and has an inclination of θ, two basis differential equations of first order are set up by considering the equilibrium of the forces and the moments on a partial wedge of soil. The distributing coefficient of active earth pressure is obtained through comparing two basis equations. The unit earth pressure and the application point of the resultant force are deduced. The effects of parameters such as the internal frictional angle of backfill, the frictional angle between the wall back and the backfill, slope angle of filling and dip angle of wall back on distributing coefficient of active earth pressure, the unit earth pressure, the application point of the resultant force, rupture angle are analyzed in detail. Meanwhile the non-linear distributing features are concluded.

Abstract: Based on modern ideas of thermomechanics, small strain dynamic dissipation function of Hardin-Drnevich model for soils is formulated using the assumptions of the beeline and the skeleton curve shift laws. The first and the second threshold shear strain are proposed. Both the two threshold shear strains do depend significantly on the dynamic parameters for soils. Comparison between the results of eight kinds of cohesionless soils, it is shown that the two threshold shear strains decrease when the maximum dynamic shear modulus coefficient and exponent increase. The first threshold shear strain basically does not change with the change of internal friction angle. However, for the second threshold strain, a monotonically increasing function and monotonically decreasing function can be used to model the change with respect to the internal friction angle for the beeline and the skeleton shift stress respectively.

Abstract: Landslide is common geological hazards to the hydropower reservoir. Reasonable parameters are the key to design and prevent the landslide. After geological exploration, a few laboratory tests (uniaxial compression test, unsaturated permeability test, unsaturated direct-shear test) were conducted for the sliding mass. In order to obtain reasonable strength parameters of sliding mass, basing on the experimental results, some researches (such as engineering analogy, parametric inversion) were performed by using limit equilibrium method. The mechanical parameters of the slope were proposed.

Abstract: For the current simplified calculation of pile-brace support structure can not calculate the displacements of pile and brace, the authors try to start from the deflection differential equation of beam on elastic foundation, considering the deformation compatibility of pile and brace, and obtains the internal forces and displacements of pile by using Finite Difference Method. Meanwhile, Finite Element Method is used to analyze and calculate the horizontal displacements of pile. The results show that the values obtained by this article are closer to the measured values than that obtained by Finite Element Method. The method is accurate, reliable and simple. Besides, this author also analysis the different horizontal displacements of pile under different parameter conditions of support structure, which can provide some valuable suggestions for the design of foundation pit.