库水-淤砂层-坝体-坝基体系地震响应分析

Seismic Response Analysis of Water-sediment-base-arch Dam System of the Reservoir

针对我国西部水利工程结构面临的地震安全问题,特别是混凝土高拱坝的抗震安全设计,以小湾水电站混凝土高拱坝为研究对象,进行了库水-淤砂层-坝体-坝基体系的耦合动力分析,同时考虑了复杂的坝基地形、正常蓄水位的库水以及常年运行而堆积的淤沙层的影响。主要内容有:①基于传递矩阵法及二维有限元,实现了复杂峡谷地形的自由场计算;②基于水-饱和多孔介质-固体的统一计算框架,实现了库水-淤沙层-坝体-坝基体系的三维地震响应分析算法。最后,分别以脉冲波和地震波作为输入,探讨了小湾拱坝的地震响应规律及库水淤沙层对拱坝地震响应的影响。结果表明:坝体顶部中心区域会承受较大的拉、压应力;而库水底部淤砂层对坝体的位移及应力影响并不显著。

Aiming at the seismic safety problems confronting the hydraulic engineering structures in western China,especially the aseismic design of high concrete arch dams,this paper makes a case study of the concrete high arch dam of Xiaowan Hydropower Station,carries out the coupled dynamic analysis of the water-sediment-dam-foundation system of the reservoir,and considers the effects of the complex topography,the reservoir water at the normal storage level,and the sediment due to the year-round operation.The main contents include:①The free field calculation of complex canyon terrain based on the transfer matrix method and 2D FEM of coupled system of reservoir water-sediment-base;②The 3D seismic analysis algorithm of the reservoir water-sediment-foundation-dam system based on the unified framework of fluid-saturated porous media-solid.Finally,this paper discusses the seismic response laws of the arch dam and the influence of the sediments on the results under the action of the loads of impulse wave and seismic wave,respectively.The results show that the central part of the dam crest will bear larger tensile and compressive stress,while the sediment does not have a significant effect on the displacement and stress of the dam.