考虑材料参数空间变异的重力坝地震损伤分析

Seismic Damage Analysis of Gravity Dams Considering Spatial Variability of Material Parameters

由于施工质量不均匀和混凝土自身的非均质性,因此重力坝坝体混凝土材料强度具有空间变异性。利用对数正态分布随机场模拟混凝土参数的空间变异性,采用中心点法将参数随机场离散为一组相关随机变量,通过结构空间位置和相关距离构建了自相关函数、得到相关系数矩阵。采用Cholesky方法分解相关系数矩阵并线性变换,通过n维独立标准正态分布样本矩阵生成n维相关对数正态分布样本矩阵,实现了混凝土材料参数空间变异性的抽样模拟。对印度Koyna重力坝的地震损伤分析表明,考虑混凝土参数(特别是抗拉强度)的空间变异性后,坝体损伤程度加重,坝顶位移振幅减小,坝顶垂直残余位移增大,因此在重力坝抗震设计中应考虑材料参数空间变异性的影响。

Since the uneven construction quality and the inherent heterogeneity of concrete,the material properties of the gravity dam have spatial variability. The lognormal distribution random field was used to simulate the spatial variability of concrete material. The concrete material parameter random field was dispersed into a set of correlated random variables by means of the Center Point Method and the autocorrelation function and the correlation coefficient matrix was constructed through structural spatial location and correlation distance. The correlation coefficient matrix was decomposed and linear transformed,the n-dimensional correlation lognormal distribution sample matrix was generated by n-dimensional independent standard normal distribution sample matrix to simulate the spatial variability of concrete material parameters.The seismic damage analysis of Koyna gravity dam in India shows that considering the spatial variability of concrete parameters( especially tensile strength),the damage degree of the dam is aggravated,the displacement amplitude of dam crest is reduced and the vertical residual displacement of dam crest is increased. Thus,the influence of material parameters spatial variability needs to be considered in the seismic design of gravity dams.