基于NGA模型的主余震序列作用下重力坝损伤破坏研究

传统的线弹性模型和弹塑性DP模型难以真实反映混凝土、岩石地基在遭遇超出其抗拉压强度时的损伤破坏规律。为更加全面地评估余震作用对已损重力坝结构的累积破坏影响,本文采用塑性损伤力学模型来模拟坝体的动力损伤,同时考虑岩石材料的非线性性质,将塑性损伤力学的方法推广到岩体材料,建立了大坝坝体与地基的整体损伤力学模型,实现了重力坝整体动态损伤演化全过程模拟。结合主震与强余震统计关系和NGA地震动衰减关系构造了主余震地震动序列,分别研究了单次主震、单次余震以及主震后余震对强震区混凝土重力坝坝体地基整体损伤演化的影响。研究结果表明:余震作用对坝基的塑性应变累积效应显著,对于主震受损的混凝土重力坝结构,余震作用能够引起结构较大的二次残余变形。

Study on damage and failure of gravity dam under main aftershock sequence based on NGA Model

The traditional linear elastic and elastic-plastic DP model are difficult to truly reflect the damage rule of concrete and rock when it encounters the strength beyond its tensile and compressive strength. In order to better evaluate the cumulative effect of aftershock on the damaged gravity dam structure, in this paper, the plastic damage mechanics model is used to simulate the dynamic damage of dam body, and the non-linear property of rock material is considered. The method of plastic damage mechanics is extended to rock material, the whole damage mechanics model of dam body and dam foundation is established,and the whole process of dynamic damage evolution of gravity dam is simulated. Combined with the statistical relationship between main earthquake and strong aftershock and NGA ground motion,the main aftershock sequence is constructed. The effects of single main shock,single aftershock and aftershock on the damage evolution of concrete dam foundation in strong earthquake area are studied. The results show that the effect of aftershock on plastic strain accumulation of dam foundation is significant. For the concrete gravity dam structure damaged by the main earthquake,the aftershock can cause large secondary residual deformation.