考虑坝体材料参数随机性的拱坝易损性分析  

Vulnerability analysis on arch dams based on spatial variability of dam materials

作　　者：徐强[1,2] 姚文斌 陈健云[1,2] 张天然 曾祥兴 XU Qiang;YAO Wenbin;CHEN Jianyun;ZHANG Tianran;ZENG Xiangxing(State Key Laboratory of Coastal and Offshore Engineering,Dalian University of Technology,Dalian 116024,China;Institute of Earthquake Engineering,Dalian University of Technology,Dalian 116024,China)

机构地区：[1]大连理工大学海岸与近海工程国家重点实验室,辽宁大连116024 [2]大连理工大学工程抗震研究所,辽宁大连116024

出　　处：《人民长江》2023年第12期202-210,224,共10页Yangtze River

基　　金：国家自然科学基金重大项目子课题“混凝土坝枢纽潜在失效模式与灾变机理研究”(52192672)。

摘　　要：施工过程和混凝土材料自身属性会导致拱坝坝体材料具有随机性。为了评估在强地震动作用下坝体混凝土材料随机性对拱坝抗震性能的影响,以白鹤滩拱坝为对象研究了表征混凝土非均匀程度的相关长度以及材料参数均值与拱坝损伤破坏的关系。分析中采用耐震时程法(ETA)生成人工地震动时程,假设坝体材料参数值服从特定区间内的均匀分布,同时为考虑坝体材料局部连续性,将相关长度引入到均匀分布公式中,基于协方差矩阵分解法和中心点离散技术建立了对应不同相关长度的拱坝随机场有限元模型,分析了其在地震动作用下的动力响应。选择相对位移、横缝开度和损伤体积比作为评价指标,通过概率密度演化法(PDEM)和直接概率积分法(DPIM)计算各指标的时变概率密度曲线,并计算了不同指标的失效概率曲线,以评价坝体在不同峰值加速度下的失效概率。分析结果表明:考虑坝体材料的随机性后,坝体损伤分布分散,且不同工况的分析结果离散性较大;损伤情况主要受相关长度和材料参数均值的影响,相关长度越大,坝体的抗震性能越好。The process of construction and the quality of concrete materials can lead to the randomness of arch dam materials.To evaluate the influence of the randomness of dam concrete materials on the seismic performance of arch dams under strong ground motions,taking the Baihetan high arch dam as a case,we investigate the relation among the relevant length that represents material heterogeneity,the mean value of material parameters and the failure of arch dams.The endurance time analysis(ETA)is used to generate the artificial ground motion time history.It is assumed that the dam material parameter value follows the uniform distribution within a specific interval.At the same time considering the local continuity of the dam material,the correlation length is introduced into the uniform distribution formula.Based on covariance matrix decomposition and center point discretization technology,we establish a finite element model of the arch dam random field corresponding to different correlation lengths.And its dynamic response under the ground motion is analyzed.The relative displacement,transverse joint opening and damage volume ratio are selected as the damage evaluation indexes.The time-varying probability density curves of each index are calculated based on the probability density evolution method(PDEM)and the direct probability integration method(DPIM),and the failure probability curves of different indexes are calculated to evaluate the failure probability of the dam body under different peak ground acceleration(PGA).The analysis results show that after considering the randomness of the dam material,the dam damage distribution is scattered,and the analysis results under different conditions are more discrete.The damage is mainly affected by the correlation length and the mean value of material parameters.The longer the correlation length is,the better the seismic performance of the dam body is.

关 键 词：混凝土拱坝 耐震时程法 材料随机性 概率密度 失效概率 

分 类 号：TV642.4[水利工程—水利水电工程] TV313