水工规范地震动模拟及高心墙坝可靠度研究

Simulations of ground motions based on Code for Seismic Design of Hydraulic Structures and study on reliability of high core wall dam

抗震可靠度评估可以有效估计大坝在地震荷载作用下的安全性。施加人工模拟的随机地震动并将结构随机响应定量化的思路受到广泛的关注。本文首先基于水工建筑物抗震设计规范,利用谱表达-随机函数的方法建立五类不同场地的非平稳随机地震动模型;其次将该模型与广义概率密度演化方法结合,以获取大坝动力响应的概率信息;最后,引入等价极值事件的思想,建立以坝体变形和坝坡滑移为指标的高心墙坝动力可靠度分析框架。以如美大坝为例的分析结果表明,计算所得坝体变形破坏比坝坡滑移破坏概率大;本文的分析框架引入荷载的随机性,可以计算出较为准确的失效概率,从而为高心墙坝的抗震可靠度评估提供依据,且在岩土工程中均具有适用性。

Seismic reliability evaluation often gives an effective estimate of the dam safety under seismic load.Recently extensive attention has been attracted by the combination of applying artificially simulated stochastic ground motions and quantifying the stochastic responses of structures.Based on Code for Seismic Design of Hydraulic Structures,this paper develops a non-stationary stochastic ground motion model for five different sites using a speactral expression-random function method.Then,we combine this model with a generalized probability density evolution method to extract probability information from dam dynamic responses.Finally,we borrow the idea of equivalent extreme value event,and construct a framework for dynamic reliability analysis of high core wall dams,with dam deformation and dam slope slip used as evaluation indexes.A case study of the Rumei Dam shows that the calculations of dam deformation failure probability are higher than those of the dam slope slip failure.Our analysis framework considers load randomness and gives more accurate failure probability,thus laying a basis for the seismic reliability evaluation of high core wall dams and its application in geotechnical engineering.