拉哇高面板堆石坝极限抗震能力分析

摘要

拉哇面板堆石坝位于金沙江上游基本烈度达Ⅷ度的强震区,为评价其极限抗震能力,采用堆石体地震残余变形、坝坡动力稳定、面板应力以及面板脱空等指标,研究了规范反应谱、坝址一致概率反应谱以及设定地震反应谱等不同反应谱在不同峰值加速度下大坝的地震动反应.结果表明:在同一反应谱下随着峰值加速度的提高,大坝的动力反应逐渐增大;不同反应谱在相同峰值加速度下大坝的动力反应呈现较大差异.一致概率反应谱条件下大坝的加速度反应、面板脱空量、堆石体残余变形和下游坝坡的滑动都明显大于规范谱和设定地震谱;设定地震谱下的大坝动力反应则略高于规范反应谱.结合反应谱的生成方式,宜选取设定地震反应谱对拉哇面板堆石坝的极限抗震能力进行评价.计算得到拉哇面板坝的极限抗震能力在0.55g～0.6g.%Lawa Concrete Face Rockfili Dam is located in the strong earthquake region with basic intensity Ⅷ of the Upper Jinshajiang River.In order to calculate the ultimate seismic capacity of the dam,the indexes,such as seismic residual deformation of the rockfill body,dynamic stability of the dam slope,stress of the face slab,void under the face slab,etc.,are adopted for studying the dam seismic dynamic responses of various response spectra,i.e.the standard response spectrum,the consistent probability response spectrum at the dam site and the setting seismic response spectrum under various peak accelerations.The result shows that under the same response spectrum,the dam dynamic response increases along with the increase of the peak acceleration,while the dam dynamic response presents a larger difference under the same peak acceleration with different response spectrum.Under the consistent probability response spectrum,the acceleration response of the dam,the void under the face slab,the seismic residual deformation of the rockfill body and the sliding of the downstream slope are all obviously larger than those under both the standard response spectrum and the setting seismic response spectrum,while the dam dynamic response under the setting seismic response spectrum is a little bit higher than that under the standard response spectrum.Combined with the generation mode of the spectrum,the setting seismic response spectrum is better to be selected for assessing the ultimate seismic capacity of Lawa Concrete Face Rockfill Dam.The calculated ultimate seismic capacity of the dam is 0.55g ～ 0.6g.