近断层脉冲型地震动对深厚覆盖层上高土石坝动力响应的影响研究

近年来,近断层地震动引起了工程界的密切关注,水工方面的相关研究主要集中在混凝土重力坝,对高土石坝的研究甚少,尤其是近断层脉冲型地震动的影响尚不明确。因此,结合我国西部强震区一些已建和拟建在深厚覆盖层上的高土石坝,开展脉冲型地震动对高土石坝抗震安全的影响研究是十分必要的。采用弹塑性本构模型进行有限元计算,对比分析脉冲型与非脉冲型地震动作用下大坝的动力响应。结果发现,脉冲型地震动对深厚覆盖层上高土石坝的加速度响应有一定影响,并使坝体在极短的持时内产生较大的坝体变形,不利于大坝安全。因此,建议在强震区、深厚覆盖层上修建高土石坝时,将近断层脉冲型地震动作用下的大坝抗震安全评价作为一个关键环节。

Study on impact from near-fault pulse-like ground motion on dynamic response of high rockfill dam on deep overburden

In recent years，the near-fault ground motion draws great attention from engineering field，while the relevant researches in the aspect of hydraulic engineering are mainly concentrated on concrete dam，but the researches on high earth-rockfill dam is less，especially that the impact from the near-fault pulse-like ground motion is still not so definite. Therefore，it is necessary to carry out the study on the impact from the pulse-like ground motion on the seismic safety of earth-rockfill dam in combination with those constructed and proposed high earth-rockfill dams on deep overburden within the meizoseismal region in the West China. The dynamic responses of the dam under the pulse-like ground motion and the non-pulse-like ground motion are comparatively analyzed herein through finite element calculation made by the relevant elastoplastic constitutive model. The result finds out that the pulse-like ground motion has a certain impact on the acceleration response of the high earth-rockfill dam on deep overburden，and makes the dam body largely deformed in a very short period of time，which is unfavorable to the dam safety. Therefore， it is suggested that the assessment on the seismic safety of high earth-rockfill dam under the effect of near-fault pulse-like ground motion is to be taken as a key link when it is to be built on deep overburden within meizoseismal region.