混凝土材料非线性对拱坝抗震安全评定的影响研究

Research on effects of concrete material nonlinearity on evaluation of seismic safety of arch dams

研究地震激励下混凝土材料非线性的动力行为,建立模拟地震激励下大坝非线性动力损伤的理论与方法,对于大坝抗震安全评定具有重要意义。本文以小湾拱坝为例,引入损伤因子,利用塑性损伤模型来模拟拱坝的材料非线性行为,对拱坝坝体上、下游最大主应力、坝体位移、裂缝开展范围及坝体超载安全系数几方面进行研究分析,结果表明坝体材料非线性对坝体动力响应影响显著,塑性损伤模型比线弹性模型能更好地模拟坝体在地震激励下实际的受力行为、变形和损伤程度。从而,本文进一步揭示拱坝动力损伤灾变机理,为进行大坝抗震安全评定与设计提供理论基础。

It is important to study the nonlinear dynamic behavior of concrete material and establish the nonlinear dynamic damage theories and methods for arch dams under seismic excitation. This study adopts a damage plasticity model and introduces a damage factor to simulate the nonlinear behavior of concrete material for the Xiaowan arch dam. The maximum principal stress on upstream and downstream faces, dam displacements, the area of development of cracks as well as the safety factor of overloading are also analyzed. The results show that the effects of material nonlinearity on the dynamic response of the dam are significant. With a plastic damage model, the simulation of stresses, deformation and damage of the dam under seismic excitation is improved over the linear elastic model. This paper reveals a mechanism of dynamic catastrophic damage of arch dams, which may provide a theoretical foundation for seismic safety evaluation and design of arch dams.