Advanced Materials Research Vols. 255-260

Abstract: The use of Geosynthetic Material is developing in different countries. They are using from Geosynthetic Material in pavement to control and prevent from critical failure such as permanent deformation or rutting and reflective cracks. These materials are effective in reduction of pavement vertical deformation; because they increase shear bearing capacity in soil and aggregated layers. In present research, some scientific resources, which have referred to Geosynthetic Material usage in development and operation activities, are presented. In continuation, the appropriate depth of Geosynthetic layer is calculated by used software. By considering the obtained result; whatever the Geosynthetic layer is nearer to surface, the rutting depth will be fewer. The fully bounded operation of this layer causes its function prevents from this kind of failure.

Abstract: Sudden reduction tube was always used in spillway tunnel, drainage pipes and so on. The energy loss coefficient of sudden reduction tube flows is an important index of sudden reduction tube. In the present paper, this coefficient and relative parameters, such as the contraction ratio and Reynolds number of the flow through sudden reduction tube, were analyzed by theoretical considerations, and their relationships were obtained by the numerical simulations. It could be concluded that the energy loss coefficient was mainly dominated by the contraction ratio. The less the contraction ratio is, the larger is the energy loss coefficient. When Reynolds number is more than 10⁵, Reynolds number has little impact on it. An empirical expression, which was verified by comparison with other experiment data, was presented to calculate the energy loss coefficient of sudden reduction tube flows.

Abstract: The simulation of hydraulic characteristics was carried out with Larger Eddy Simulation (LES) and Volume of Fluid (VOF) method. The numerical results show that the flow condition is smooth, the length of lateral cavity gradually increases with the size of lateral enlargement increases, the maximum pressure value on the lateral wall appears after the bottom cavity, the upper part of the lateral cavity region was longer than the lower part due to gravity and the backwater does not intrude into bottom cavity. The numerical results agree well with the experimental date. The new lateral aerator has good hydraulic characteristics and the LES with VOF method can well predict the hydraulic characteristics after the new lateral aerator.

Abstract: Wanjiakouzi arch dam is constructed in a complex geological site, where a large number of faults, interlayer shear bands and karst zones exist in the dam foundation and abutments. The weak rocks have a bad effect on the stability of the arch dam. In this paper, the displacement distribution and stress field of the arch dam are analyzed using 3D nonlinear finite element method. The numerical results show that displacement between both left and right bank abutments is obviously asymmetric and there is greater compression and shear deformation along the faults under the thrust of the arch dam. Furthermore, the tensile stress at dam heel cannot meet the requirement of the design specifications. Therefore, it is necessary to reinforce the dam foundation and abutments to improve the ability to resist deformation of abutment. By taking such reinforcement measures as concrete plugs and consolidation grouting for weak zones, the asymmetric displacements between abutments are decreased significantly and the tensile stresses of dam heel meet the stability requirement.

Abstract: As a competitive dam style and full of life-force, the concrete- faced rockfill dam (CFRD) is widely used in China in recent years. Experts in China pointed out that “Extra high CFRD generally means those CFRDs with their heights higher than 150 m ” However, the history of construction and design of extra high CFRD is short and some problems during the construction of Extra high CFRD is still need to be explored. Therefore, stress and deformation characteristic of DongQing extra high CFRD was analyzed by 3D finite element method and some beneficial reference was obtained. Firstly, the advanced 3D mesh generation procedure written by Fortran language was used to form the finite element mesh which contained not only the dam with large amount of vertical joins and perimeric joints, but also the rock foundation and surrounding mountains. Moreover, the layer by layer construction procedure of dam was detail considered during 3D mesh generation. Since the node number of 3D mesh is still larger, large scales equations solving method-element by element method and others efficient measures were adopted. As the results, the computer calculation time decreased from former 48 hours to 20 minutes. According to the calculation results, the design scheme of DongQing CFRD was finally optimized.

Abstract: Proper mechanical parameters of slope rock mass are the premise which ensures the smooth progress of slope stability calculation. By analyzing the geological information of the yinshuigou accumulation slope on ridge 2 in Xiaowan hydropower station, and according to the deformation and damage in the excavation of the accumulation slope, this paper inverts the shear strength parameters of the accumulation slope by using 2D rigid limit equilibrium method. On base of unloading rock mass mechanics methods, the stress and strain analysis to the accumulation slope is studied by using 3D finite difference method, and by contrast of the monitoring displacement and calculated displacement in slope-direction about the key point of the accumulation slope , the article inverts the deformation parameters of the accumulation slope. Finally, the shear strength parameters in the contact zone are ascertained as: C=0.04MPa, Φ=30°, and the deformation parameter of the accumulation slope is changed from the initial 1.5MPa to 0.95MPa by the damage unloading.

Abstract: Rainfall is one of the main factors that influence the stability of slope. Rainfall infiltration will cause soil saturation changing and further influence pore water pressure and medium permeability coefficient. Based on porous media saturation-unsaturated flow theory, the slope transient seepage field is simulated under the conditions of rainfall infiltration. It is shown that change of pore water pressure in slope soil lag behind relative changes in rainfall conditions. As the rainfall infiltrate, unsaturated zone in top half of slope become diminution, the soil suction and shear strength reduce, so stabilization of soil slope is reduced.

Abstract: In this paper, time domain transient analysis of dam-reservoir interaction is studied. Resulting hydrodynamic pressure is exactly calculated including the effect of vertical component of earthquake acceleration as well as the horizontal component. Method of separation of variables is applied to solve resulting partial differential equation after applying Laplace transform. Sommerfeld’s boundary condition is used in far end of the infinite reservoir. Finally, a comparison is made between the results of the case involving both horizontal and vertical accelerations and the case of applying vertical component only using El Centro earthquake (1940) data.

Abstract: According to the modified Эиванков calculation method and the balance relationship between representative ship effective thrust and resistance, the calculation method of maximal effective thrust is established by transforming hydrodynamic condition to hydrostatics condition due to the hydrodynamic complexity. One calculation method of navigable hydraulic parameters adapted for Jinsha River is put forward and applied successfully in prototype tests at Shuifu Port in Jinsha River.This method is convenient for application and can provide references for calculating navigable hydraulic parameters in other rivers.

Abstract: The aim of this research is to improve characteristic of magnetorheological fluid, and to supply theoretic basis for preparing MRF and applying MRF. By molecular dynamical simulation in MATLAB, microstructure of MRF, mechanism of MRF, and factors of affecting MRF characteristic were investigated. Based on theory of magnetic dipoles and microstructure characteristic of MRF, various factors affecting magnetic chain structure were considered, microcosmic model of MRF was established, factors affecting velocity of MRF forming chains were analyzed.