超强地震作用下拱坝的损伤开裂分析

本文根据混凝土抗拉软化特性，基于混凝土塑性损伤模型，分析了大岗山双曲拱坝在超强地震荷载作用下的损伤开裂。研究采用非线性有限元的精细网格，考虑横缝非线性效应，应用时域方法分析了高拱坝在超强地震作用下的开裂形式以及损伤随着地震时程的发展情况。研究表明，拱坝在0.56g(PGA)超强地震荷载下坝体中上部梁向损伤指数达到0.9，拱坝该部位可能发生损伤开裂。同时由于损伤使坝体刚度下降导致坝顶位移与横缝开度显著增大，如横缝开度最大由16.2mm增大到36.8mm，因此需要考虑采取坝体抗震加强措施。

Analysis of damage and cracking in arch dams subjected to extremely strong earthquake

The plastic damage model of concrete is applied to analyze the cracking of the Dagangshan double curvature arch dam under the action of extremely strong earthquake, in consideration of the softening behavior of tensile strain. Nonlinear FEM with refined mesh is adopted and the nonlinear effect of the transverse joints is taken into account. The time domain method is used to analyze the form of failure and the development of cracking following the time history of the earthquake. The result shows that the damage index may reach 0.9 and the failure may occur to the upper cantilever portion of the dam when subjected to an extremely strong earthquake with PGA = 0.56g. The displacement response and the opening of contraction joints will significantly increase. Consequently, the strengthening measures for ensuring the safety of dam are necessary.