边界条件对土石坝地震反应的影响研究

Study of influence of boundary condition on rockfill dam seismic response

土石坝地震反应分析中,需要对有限网格的边界条件进行处理,以反应实际地基在空间上的无限性。分别采用黏性边界和刚性边界,对土石坝进行了动力分析。结果表明:随着坝高增加,黏性边界对坝顶加速度反应影响逐渐增大;对于均质坝,考虑黏性边界计算的坝顶加速度反应约比刚性边界低10%~30%;对于实际双江口直心墙土石坝,考虑黏性边界计算的坝顶加速度反应约比刚性边界低30%~40%左右。

In order to simulate the infinite domain,a special boundary condition should be used in the dynamic analysis of rockfill dam with the finite element method.A series of dynamic analyses are performed in time domain by using viscous and rigid boundary respectively and compared with dynamic analysis results in frequency domain.The results show that,with the increase of the height of rockfill dam,the influence of viscous boundary become increasingly obvious.The acceleration of dam top calculated with viscous boundary is lower 10%~20%than that with rigid boundary for homogeneous dam.For the Shuangjiangkou Clay Core Rockfill Dam,the acceleration of dam top calculated with viscous boundary is lower 30%than that with rigid boundary.