Advanced Materials Research Vols. 243-249

Abstract: Time history analysis is performed on geotechnical engineering structures under earthquake actions using 3D nonlinear FEM. The distribution of internal force on slide surfaces has been interpolated from the stress field of FEM with 3D Multi-grid Method. The safety factor with time history of sliding block can be obtained by limit equilibrium analysis and its dynamic stability can be evaluated. For blocks sliced by single slide surface and wedge-shaped double slide surfaces, general formulas of safety factor are given and their applicability have been analyzed. Analysis and evaluation of slide block aseismic stability are performed on high slope on the right bank of Dagangshan arch dam.

Abstract: The three-dimensional finite element numerical model of wind power generator unit is created by using ANSYS. The elastic-plastic constitutive is introduced and the nonlinear contact is set up between the foundation stub and concrete. The different reinforcement arrangement’s impact on structure is researched, the strength characteristic and law of reinforcement concrete is discussed and a more rational scheme is raised. It’s more rational to consider the contact status and material nonlinearity. The research results offer scientific basis for design and optimization on foundations of wind turbines.

Abstract: The overall structure of a hydropower plant with bulb tubular units is calculated and analysed in 6 kinds of load cases, and the maximum stresses in different directions and the positions where the maximum stresses appear in the hydropower plant structure. The conclusions show that the plant is safe and the design is reasonable.

Abstract: Considering the effect of the actual landform and the pile-soil dynamical interaction, this paper uses the dynamic time interval analysis to analyze the response of horizontal seismic load of different segment lengths of high-piled wharfs. It makes research on the relative displacement, the acceleration, the maximum stress and the shear stress of the wharf construction and the variation of the shear force, the bending moment and the torque of the pile in the action of acceleration in true earthquake records. It determines the reasonable subdivision length of high-piled wharf in actual coast. Calculations show that, the wharf torsion caused by the asymmetry of terminal structure and pile, and the uneven stratum facilitates the response, and increases the shear stress of the pile. The placement of piles and the uneven stratum are the main factors of the internal force of terminal structure in action of earthquake, The optimal design of partial reinforcement should be adopted due to the considerable shear stress on the bezel panel. This method can provide reference to the design of the terminal structure in deep sea as well.

Abstract: The paper assesses groundwater quality and productivity in Melaka, Peninsular Malaysia. 238 data set shallow boreholes, 20 data set deep boreholes were collected and continuous pumping test data were used to determine productivity of the aquifers. 68 water samples were tested for water quality. The productivity of the wells and the characteristics of the aquifer were evaluated by pumping test using both the constant discharge rate and steps drawdown methods. The potential of shallow groundwater is low with average discharge <5 m³/hour. The potential of deep groundwater is high category with average discharge > 20 m³/hour. The results show that 32% (538 km²) from total area of Melaka district (1650 km²) is low potential categories, 56% (922 km²) is moderate and 12% (194 km²) is high. Based on the chemical data, the quality of deep aquifer is fresh. Therefore, it is available for drinking water with minimum treatment.

Abstract: On the condition of different dam heights and different shapes of river valley, 3-D dynamical responses of concrete-faced rockfill dams subjected to different seismic intensity input are analyzed based on equivalent-linear model in this paper. The results show that on the condition of the same dam height and the base acceleration excitations unchanged, the position of the maximum acceleration on the axis of the top moves from the middle to the riversides symmetrically with the increase of the river valley width. For the narrow river valley, the position of the maximum acceleration which occurs near the riversides to the wide valley is on the middle of the axis at the top. The result negates the application of 2-D dynamical computation for wide valleys, and shows that for the seismic response of high concrete-faced rockfill dams, the seismic amplification factor along the axis should be given, except for that along the dam heights. Statistical analysis is also made to the seismic coefficient, and an empirical equation for calculating the maximum acceleration of the dam is provided, which provide an reference for the seismic stability analysis of rockfill dams using pseudo-static method.

Abstract: Evaluating the wetting induced deformation of the shell is one of the most important issues in designing a high rockfill dam. Excessive wetting deformation and the relevant stress deterioration in adjacent impervious structures may cumber the normal operation of the engineering and seriously risk the safety of the dam. In this paper, a hypoplastic creep model is incorporated into a finite element procedure to study the wetting induced deformation of a rockfill dam. Considerable lateral movement towards the upstream and an additional wetting collapse presented in the upstream shell induced by reservoir impounding is effectively predicted by the finite element model. The reasonable results confirm the feasibility of applying the hypoplastic model to the evaluation of the wetting induced deformation in dam engineering.

Abstract: Suppose there is time course during the cracking and deforming process, the tensile cracking of rock-concrete materials was analyzed by means of elasto-viscoplastic model and its calculation steps were illustrated as well in this paper. The expression of function Φ in elasto-viscoplastic theory was studied; what’s more, it was comparatively analyzed the tensile cracking of rock-concrete materials by elasto-viscoplastic model and the maximum tensile stress criterion respectively. There are some differences comparing with the study of plastic yield by elasto-viscoplastic model, when analyzing the tensile cracking of rock-concrete materials on the basis of elasto-viscoplastic model, the function Φ should be the stress or stress formula of the direction where the principal stress firstly reaches the tensile strength; it is proved by the example analysis that it is feasible to study the tensile cracking of rock-concrete materials by elasto-viscoplastic model and there is no iteration stability issues.

Abstract: The 2-D water and sediment mathematical model which reflects flood retarding and sand silting of flood plain in the Lower Yellow River has been set up in this paper. Through carrying on 2-D water and sediment numerical simulation of the “96.8” typical flood, the authors studied influence of zoning flood retarding and sand silting on flood travel, flow structure of floodplain-channel and transver exchange of water and sediment. The simulating results in different conditions show that, adopting the zoning flood retarding and sand silting in the Lower Yellow River effectively worked on retarding flood and sharpening peaks in the flood retarding basin, guaranteed and expanded transver exchange of water and sediment in the floodplain and channel and maintained the river channel’s vigor. This can relieve “secondary suspended river” states in the Low Yellow River to a certain extent.

Abstract: In the numerical calculation of geotechnical project, it’s difficult to confirm the parameters because of the complexity and the uncertainty of them as the time is changing. However, the back-analysis provides us an effective way. Based on the result of the triaxial test on rock-fill of Shui Bu Ya CFRD, the thesis adopts the direct back-analysis method which combines the BP Neural Network and Genetic Algorithm to calculate the Tsinghua non-linear K-G model parameters of the rock-fill. The back-analysis parameters are used to simulate the filling process of Shui Bu Ya CFRD and predict the displacement of the dam. The thesis provides a technical reference for displacement back-analysis of soil parameters for CFRD.