某重力坝冲砂孔坝段地震动力反应规律及抗震安全性分析

Dynamic seismic response law of souring sluice section of a gravity dam and analysis of its seismic safety

以我国西南地区某重力坝冲砂孔坝段作为依托工程,应用三维有限元动力时程分析方法,针对坝顶特别宽厚、上游坝面突出及坝体内部布设孔洞等重力坝结构变动因素对大坝地震动力反应的影响规律开展了研究。研究结果表明,本坝段坝顶宽厚使得坝顶部位结构刚度增强,导致坝顶地震反应加速度放大效应显著小于普通重力坝,坝体颈部的地震动应力集中不甚显著,地震动应力较小;上游坝面局部突出,导致坝体顺河向地震加速度呈现左侧小于右侧的不对称分布规律,外凸部分横河向地震加速度则明显大于坝体加速度。本文研究结论可为同类重力坝工程的抗震设计工作提供有益的参考。

Taking the souring sluice section of a gravity dam in southwest China for example,the influence law of structural variation factors of gravity dams including special wide dam crest,extruding of upstream surface and shafts,galleries and holes in dam body etc. on the seismic responses of the dam is studied with three-dimensional finite element dynamic time-history analysis method. The results show that the wide and thick dam crest makes the structural stiffness of the dam crest strengthened,resulting in the acceleration amplification effect of the seismic response of the dam crest significantly less than that of the ordinary gravity dam,the seismic stress concentration at the neck of the dam body is not significant,and the seismic stress is relatively small;the protruding(outburst)of the upstream surface leads to the asymmetric distribution of the seismic acceleration along the stream direction,which is smaller on the left side than on the right side. The transverse seismic acceleration of convex part is obviously greater than that of the dam body. The conclusions of this study can provide useful reference for seismic design of similar gravity dams.