Applied Mechanics and Materials Vols. 405-408

Abstract: This paper shows the result of the research on the stability of loess high slopes with 30m and 80m in Huangshui River basin. The investigations carried out the numerical simulations of the slope stability based on the drilling and sequence sampling test in a typical loess stratum of the survey region. The result shows that the mechanisms of fracture related to the gradients of slopes are different and the limit equilibrium angles of slopes are 60° and 37° respectively.

Abstract: The determination of the phreatic line under the action of rainfall and reservoir water level fluctuation together is of great importance for reservoir slope stability analysis. However, there are no unified Formulas for the calculation of phreatic line. Homogeneous reservoir slope seepage model with inclined impermeable bed is built. Then, a conceptual model is set up based on the basic principle of seepage theory, and the approximate analytic solutions of phreatic line are derived with the Boussinesq Differential Equation of unsteady infiltration and initial value calculated in steady flow condition. And the simplified Formula, which is convenient for engineering application, is obtained by Polynomial Fitting Method.

Abstract: Loess is widely distributed in the eastern part of Qinghai Province, because of its special nature,a large number of high and steep slopes have been formed in this area, sliding under the influence of human and natural factors,leading to economic losses. Fenghuang Mountain landslide is located in the middle district of Xining City, a the loess-mudstone contact surface landslide with its upper loess bedding sliding along mudstone contact surface. Based on the sliding mechanism, strength reduction method for slope stability analysis has been applied, showing the landslide is in the creeping stage, with the critical safety factor of 1.3 and had better taking the corresponding control measures.

Abstract: the paper introduces the basic characteristics of the landslide, analyzes the formation mechanism of the landslide, I think that the thick and loose efflorescent colluvial deposit on landslide offer material source of the landslide; Steep hill provides effective free surface for the landslide ; Heavy rainfall and human engineering activities are the main factors for the stability of the landslide. According to rock physical mechanics test and stability calculation results under different working conditions, afford a stability evaluation for the landslide. The results show that the landslide may lose stability when cutting slope in the leading edge, loading in trailing edge and suffering heavy rainfall, we should take the necessary measures to prevent and control.

Abstract: Xiayingfang mining area in the structure of the earth is part of north China platform of Inner Mongolia axis and yanshan fold belt, which belong to the northern margin of north China platform polymetallic metallogenic belt. Give priority to with silver polymetallic minerals, in the area are mainly distributed at Xiayingfang - Dongshan fault belt and its two side. Ore bodies occur mainly in group a bar at the bottom of the Tuanshanzi group banded dolomite and dolomitic limestone. After analyzing the characteristics of geophysical prospecting in the area, combined with the study of geological conditions, it is good for further prospecting.

Abstract: The pre-existing fractures in rock can close, open and growth as it subjected to mechanical or environment loading, which can in turn change the structure of the rock and alter its fluid flow properties. In order to study the crack growth processes of pre-existing fracture in rock under the condition of hydraulic and mechanical coupling, a numerical tool, named F-RFPA2D which takes into account the growth of existing fractures and the formation of new fractures, is used for this purpose. By considering the effect of hydraulic pressure filling into the wing crack, the behavior of fluid flow, damage evolution and their coupling action in the pre-existing and the newly formed fractures are studied in detail. The modeling results suggest that the hydraulic pressure in the crack enhanced the tensile stresses at the crack tips, resulting in crack growth path is different from that without hydraulic pressure loading. The wing crack growth mechanism under the coupling of hydraulic and mechanical is discussed, which provides a good reference for studying on the hydraulic fracturing in rock masses.

Abstract: Reservoir basin deformation monitoring data of some high arch dams has shown that the upstream of the dam subsided while the downstream warped upward slightly. Therefore, combining reservoir basin with high arch dam and foundation, the widespread finite element model is built and the reservoir basin deformation and its influence factor weight are determined through the simulation of the bedrock depth, the extending length of the upstream and downstream and different water levels based on an improved entropy method. The engineering simulation model has proved the reservoir basin deformation mechanism. Moreover, the reservoir basin deformation will tend to converge when the simulation model expands to certain extent. The research can provide suggestions for deformation doubts occurring during the high arch dam operation.

Abstract: Dangerous rocks are among the most significant factors in analyzing the stability of high slopes, and are the main geological hazards on such slopes. These rocks are typical spatial blocks. The unstable failure of dangerous rocks poses evident spatial features. Consequently, their stability should be calculated by considering it as a three-dimensional (3-D) problem. In this research, the general block method of fractured rock mass and 3-D discontinuous deformation analysis (DDA) are used to study the stability of dangerous rocks on the slope of a hydropower station. The general block method of fractured rock mass is used to generate dangerous rocks and to assess the geometric mobility of blocks. The progressive unstable failure of dangerous rocks is also analyzed. Moreover, 3-D DDA is implemented to examine the stability of dangerous rocks, including the regularity of their unstable failure. The failure sequence of each batch of blocks estimated by general block theory is the same as that in the results of 3-D DDA. The decrease in the shear parameters of the structural plane shortens the time interval of failures, but increases the number and capacity of blocks.

Abstract: Based on the characteristics of series compensation platform structure, a method of installing modified Pall-typed friction dampers for seismic passive control was proposed. Compared with the conventional , the modified Pall-typed friction damper has the same effect on energy dissipation, and it is superior in imposing pretension at both ends and saving friction materials. The equations of relation between brace displacement and internal force of the modified Pall-typed friction damper were derived. Besides, the time-history analysis method for seismic responses of series compensation platform structures with modified Pall-typed friction dampers was established, and a sine amplitude-modulation wave train was applied to analyzing the dynamic responses of these structures. The results show that, the displacement of the series compensation platform structures with modified Pall-typed friction dampers decrease to some extent. The seismic control is effective.

Abstract: This article presents a method of work tool modelling for machines for surfacing concrete in the form of a disc which has variable geometric friction elements. The method, based on the effectiveness criterion of the elementary interaction surface friction describes the impact of the disc material.