重力坝动态断裂分析

地震作用下重力坝的坝踵裂纹及其稳定性是工程界普遍关心的问题。本文基于比例边界有限元法（the scaled boundary finite element method-SBFEM）研究重力坝坝踵裂纹的动态应力强度因子（stress intensity factor -SIF）的变化规律。SBFEM的优点是可以给出位移场沿径向的解析解，直接按定义求出SIF，而不必对裂尖进行特殊处理。以柯依那重力坝作为算例，进行了频域法和时域法的分析，比较了不同坝踵裂纹长度的应力强度因子，计算了地震应力沿坝基交界面的变化。同时计算了裂纹内水压分布对应力强度因子的影响。计算结果表明随着裂纹长度的延伸， 的峰值逐渐增大；裂纹内水压力越大，对应力强度因子的影响越大。研究成果对重力坝抗震安全性评价具有重要意义。

Dynamic Fracture Analysis of the Gravity Dam

Crack formulated at the heel of concrete gravity dam subjected to earthquake excitation is a problem of much concern in the engineering community. Based on the scaled boundary finite element method (SBFEM) the variation of the dynamic stress intensity factors (SIF) at the heel of gravity dam has been studied. SBFEM has the advantages that the stress field along the radial direction can be solved analytically, it allows SIF to be determined directly from its definition, no special crack tip treatment is needed. The Koyna gravity dam is analyzed as a numerical example. Time domain and frequency domain analysis have been carried out. The SIFs with different length of cracks at the dam heel have been evaluated and compared, the variation of stress along the dam foundation interface is exampled. In addition, the effect of the water pressure distribution inside the crack at the dam heel is also studied. The results show that the max value of vary distinctly with the increase of crack length. Furthermore, the SIF tends to increase with higher in-crack water pressure. The research results have great significance for the evaluation of earthquake stability of concrete gravity dams.