Abstract

Spatial variability of tensile strength, widely existing in concrete gravity dams due to the influence of long construction period and heterogeneous construction quality, has a profound impact on the nonlinear behaviour of structures. In this paper, a method to simulate the random field of the tensile strength of concrete gravity dams based on the random field theory is proposed. A typical non-overflow dam section of the Guandi gravity dam is taken as an example, artificial seismic waves with similar response spectra and natural seismic waves with different magnitudes are selected for the comparative analysis. Based on the concrete damage plasticity (CDP) model and incremental dynamic analysis (IDA) method, the damage characteristics, failure modes, probability density evolution processes, and fragility curves obtained from gravity dams with homogenous and random fields of tensile strength are compared with each other. The differences among waves and realisations of random fields are also investigated. It is seen that the spatial variability of tensile strength aggravates the damage degree, decreases the continuity of local damaged areas, and increased the failure probability of global dams. It reveals that the random characteristics affect the dams’ nonlinear behaviour directly.

摘要

由于施工周期长、施工质量参差不齐，混凝土重力坝普遍存在抗拉强度的空间变异性，对结构的非线性行为有着深远的影响。本文提出了一种基于随机场理论的混凝土重力坝抗拉强度随机场模拟方法。以官地重力坝典型的非溢流坝段为例，选取响应谱相似的人工地震波和不同震级的天然地震波进行对比分析。基于混凝土损伤塑性（CDP）模型和增量动力分析（IDA）方法，对损伤特征、失效模式、概率密度演化过程，和从具有均匀和随机拉伸强度场的重力坝获得的脆性曲线相互比较。还研究了波和随机场实现之间的差异。可见，抗拉强度的空间变异加剧了破坏程度，降低了局部破坏区域的连续性，增加了全球大坝的破坏概率。它揭示了随机特性直接影响大坝的非线性行为。