均质土坝非平稳随机地震反应分析  

Non-Stationary Stochastic Seismic Analysis of Homogeneous Earth Dam

作　　者：王志华[1] 胡庆兴[1] 

机构地区：[1]南京工业大学岩土工程研究所,南京210009

出　　处：《防灾减灾工程学报》2010年第1期35-40,47,共7页Journal of Disaster Prevention and Mitigation Engineering

基　　金：江苏省"六大人才高峰"项目(2006);江苏省土木工程与防火减灾重点实验室开放课题(2006)资助

摘　　要：考虑地震荷载的随机性及强度、频率的非平稳性,基于作者提出的适用于非平稳随机过程的一般随机地震动模型,采用虚拟激励法,建立了非平稳随机地震反应分析方法,并将其应用于某实际均质土坝动力分析中。土石坝及坝基体系采用整体有限元离散,坝体和坝基材料的动力非线性性能以等效线性化方法考虑。首先,基于目标加速度时程的强度和能量信息,确定了作为输入的加速度时—频演变功率谱密度;其次,比较了确定性时程动力分析和非平稳随机分析的结果,探讨了频率非平稳随机地震激励下的土石坝地震反应特性;最后,比较了2种不同坝基条件下的土石坝非平稳随机地震反应,探讨了频率非平稳随机激励下的土石—坝基动力相互作用。分析结果表明:地震动的频率非平稳性对土石坝动力反应有一定影响;坝体—坝基动力相互作用在地震过程中的不同阶段表现有所不同,主震阶段的相互作用显著。A method for the non-stationary stochastic seismic analysis is developed on basis of the general stochastic seismic motion model proposed by the first author to account for the randomness of the seismic loading as well as the non-stationarity of the stochastic process in the aspects of its intensity and frequency spectrum,and has been applied in a dynamic analysis of a homogeneous earth dam with the pseudo excitation method.The dam-foundation system is discretized by the finite element method,and its material nonlinearity is considered with the method of equivalent linearization.Firstly,the input time-frequency evolutionary power spectrum is defined according to the intensity and energy information of target acceleration history.Secondly,the seismic performances of the earth dam during the frequency non-stationary seismic excitations are discussed through comparing the results from determinate time-history analysis and stochastic analysis.Finally,the dynamic dam-foundation interaction is discussed through comparing the seismic responses of the dam under two different conditions of the foundation.The analysis results indicate that the frequency non-stationarity of the seismic motion has some influence on the dynamic response of the dam.In different phases of the earthquake process,effects of the dynamic dam-foundation interaction are different.The interaction is rather prominent in the main shock phase.

关 键 词：随机地震动 均质土坝 频率非平稳 坝体-坝基动力相互作用 

分 类 号：TU435[建筑科学—岩土工程]