基于动接触力法的拱坝坝肩抗震稳定有限元分析

Improved FEM based on dynamic contact force method for analyzing the stability of arch dam abutment

本文提出了应用基于动接触力方法的显式有限元技术进行拱坝坝肩抗震稳定分析的新思路,给出了相关公式。新的分析方法,将坝肩岩体、地基、坝体和库水作为一个统一体系进行动力分析计算,能有效地考虑坝肩可能滑动块体与坝体的动力相互作用,较真实地反映拱坝和坝肩受到地震作用的实际状态,并对小湾拱坝坝肩抗震稳定进行了分析研究。结果表明:在设计正常水位情况,小湾拱坝的地震作用超载安全系数约为1 3;在设计地震作用下,小湾拱坝的"降强安全系数"仅为2 58,而仅考虑静载作用时,即使以拱坝坝端应力不超过静态抗拉强度作为达到极限状态的工程判别定量标准,其坝肩的静态"降强安全系数"也高达4 0以上。因此,地震的作用使安全系数有较大降低。小湾拱坝坝肩抗震稳定是安全的,但安全裕度不高。

Based on dynamic contact force and FEM a new method for analyzing the stability of arch dam abutment is proposed. In this method, the possible sliding rock blocks, dam foundation, arch dam and reservoir water are regarded as an integrated system, so that the dynamic interaction between the blocks and dam body can be effectively considered. The analysis of arch dam in Xiaowan Hydro Project, 292m in height, is used as an example for demonstration of this method. It is found that the safety factor of the arch dam will be remarkably reduced under the action of earthquake. However the dam is safe though the safety factor is not very high.