Papers by Keyword: Hydraulic Structure

Abstract: The new arms form of radial gate—dendritic arms is introduced for the proper mechanical mechanism, however the stability design is very difficult. According to the stability theory of structure, the stability analysis model of step column with lateral restraints was proposed for dendritic arms, some equations was derived from the principle of minimum potential energy, the practical formulas of buckling bearing capacity and effective length coefficient were provided. According to an example, the accuracy on formulas was verified by finite analysis method.

Abstract: At present, many hydropower stations eliminate the expansion joints to solve the pipe leakage problem. It’s very important to control the welding environment temperatures in eliminating the final weld joint of the expansion joints. To address this problem, by adopting three-dimensional finite element model in studying the hydro project of Wanjiazhai, this paper analyzes the stress state of steel pipe in all welding environment temperatures in details and suggests the proper range of welding environment temperatures. Researchers suggest that May is suitable to perform welding.

Abstract: In the considering problem usual tasks of designing ground dams (evaluation of filter strength, compressibility and ground permeability) are overlaid by new tasks, that have never touched upon earlier, that provide reliability of earth dams under extreme conditions and that are exposed by new additional forces such as intensive deformation and curvature of base. Here are dependences allowing determination of accepted values of earth surface deformation of ground dams on undermined territories. Using this methodology, you can compute required constructively technologic protection measures. Solution of such problems as predicting behavior and degree of reliability from external influence of a dam at given expected deformations, - can be brought into action. Prediction of conventional dams reliability may been carried out without underworking.

Abstract: Human comfort is of great importance to main powerhouse and vibration level should be controlled below the human comfort limit. Comparison of ISO2631/1-1985 and ISO2631/1-1997 was performed firstly in this study. It points out that weighted root-mean-square acceleration is basic variable for vibration evaluation. The reduced comfort boundary of 2 hours (0.260m/s²) in 1985 version is very close to the comfort threshold (0.315m/s²) in 1997 version. Above two values were selected as human comfort standard in this paper. After that, 3D dynamic finite element model of HongPing pumped storage station was established and vibration analysis under pressure fluctuations was conducted using time history method. The calculation results indicated that vibration of generator floor was mainly caused by the multiples of runner blade number frequency. Vibration level of generator floor would not lead to human discomfort.

Abstract: ANSYS was used to focus on comparative analysis of several artificial boundary conditions that are widely used in engineering applications. The accuracy and stability of dynamic analysis results were then analyzed in details of a semi-infinite foundation with different artificial boundaries and different frequency input loads. Lastly, the seismic response of a gravity dam-foundation rock system was explored numerically. Experimental results revealed the simulation accuracy of artificial boundaries was closely related to the dynamic characteristics of input load and the elastic wave velocity. When the input load frequency was high, only the material with comparably higher elastic wave velocity could maintain the stability of the artificial boundary. Viscoelastic artificial boundary is practically simple and can better simulate the semi-infinite material elastic recovery ability and energy radiation outside the boundary.

Abstract: The flow-induced micro-vibration in Shuifu County Town near Xiangjia Dam is studied in this paper. First the characteristics of the micro-vibration are investigated based on the in situ measurement, and then the dynamic property of the still basin which is thought to be the vibration source is analyzed with the effect of fluid-structure interaction (FSI) considered. Finally, the reason of the micro-vibration in Shuifu county town is discussed and several possible engineering suggestions for vibration reduction are also proposed.

Abstract: A kind of crack with similar characteristics has been discovered on the upstream surface of super-high arch dam. In this paper, the reason of cracking was analyzed by the three-dimensional finite element method. It is found that the stress concentration of concrete near the water-stop structure led to the concrete initial cracking in the process of transverse joint open.

Abstract: In this paper, the crack stability and crack propagation regularity of the upstream surface of super-high arch dam along the water-stop structure were analyzed in the framework of fracture mechanics. According to fracture toughness of dam concrete, the relationship between the crack propagation length and the allowable water pressure was studied. Finally, two main specific engineering suggestions for avoiding this kind of crack on the upstream surface of super-high arch dam were given: (1) the value of checking water pressure should not exceed 0.4 MPa; (2) the flange of the water-stop structure near the upstream surface of dam should be changed toward the downstream.

Abstract: The calculation method of the minimum aperture of transverse joints with spherical surface key groove was introduced in this study. Based on the computation theory of allowable height difference between adjacent monoliths proposed by Bofang Zhu, the analytical model of allowable height difference of Xiluodu arch dam was established with consideration of the effect of main factors on the transverse joints deformation, including the temperature, autogenous volume deformation, self-weight and foundation. After the horizontal and vertical deformations of transverse joints was required, according to the form of spherical surface key groove, the aperture of each part of key groove and the minimum aperture were obtained at several height difference between adjacent monoliths. The allowable height difference was determined on the condition of meeting the grouting requirements of transverse joints. The result shows that the allowable height difference for Xiluodu arch dam should not be more than 30m.

Abstract: To solve the problem of sediments on seismic response of concrete dams, pressure wave formula of saturated porous fluid-solid two-phase medium was derived from the Biots consolidation theory, and was determined the seismic response magnitude of sediment on concrete dam. Sediment was regarded as elastic-plasticity. And the method was applied to analyze the influence of sediments density, cohesion and friction angle on dam seismic response. Finally, a typical example is analyzed. The result shows sediments plasticity is relatively obvious on dam seismic response.