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以紫坪铺面板堆石坝为例,基于堆石料的黏弹性模型和地震残余应变模型计算分析了高混凝土面板堆石坝的地震响应,并结合震害调查结果分析了高混凝土面板堆石坝的地震损伤机理。研究表明,输入地震加速度在坝顶附近和坝坡表面显著放大,呈现出显著的鞭梢效应,导致坝顶和下游坝坡上部堆石体松动滚落。地震导致大坝堆石体产生显著剪缩,坝体断面整体向内收缩,刚性混凝土面板与垫层料之间脱空,脱空后面板与垫层料之间的摩擦力大幅减小甚至消失,面板在自重和地震惯性力联合作用下向下滑动,致使面板水平施工缝发生错台,面板表面产生裂缝。地震还导致岸坡附近左右坝段堆石体向河谷中央位移,致使岸坡附近面板垂直接缝发生拉伸破坏,河床中部垂直接缝及附近混凝土面板发生挤压破坏。数值计算和震害调查结果均表明,高混凝土面板堆石坝的地震损伤现象主要与其堆石体地震残余变过大,以及堆石体与防渗系统之间变形不协调密切相关,故强震区修建高面板坝应尽可能提高堆石体压实密度,以减小坝体的地震残余变形。
Taking Zipingpu Concrete Faced Rockfill Dam as an example, the seismic response of high concrete face rockfill dam is calculated and analyzed based on the viscoelastic model of rockfill materials and the residual strain model of the earthquakes. Combined with the survey results of the earthquake damage, the concrete face rockfill dam Earthquake damage mechanism. The results show that the input seismic acceleration is significantly magnified near the crest and on the surface of the slope, showing a significant whiplash effect, resulting in loose rocking of the top of the crest and downstream rockfill. Earthquakes lead to significant shrinkage of the rockfill dam body, the overall contraction of the dam body inward, rigid concrete panels and cushion material between the void, the gap between the rear panel and cushion material significantly reduce the friction or even disappear , The panel slides downward under the joint action of self-weight and seismic inertial force, resulting in a wrong platform at the horizontal construction joint and a crack in the panel surface. The earthquake also caused the left and right dam rockfill bodies to displace towards the center of the river valley, resulting in tensile failure of the vertical joints near the bank slope and the vertical seams in the middle of the riverbed and the adjacent concrete panels. The results of numerical calculation and earthquake damage survey indicate that the seismic damage of concrete faced rockfill dams is mainly related to the large residual deformation of the rockfill body and the uncoordinated deformation between the rockfill body and the seepage control system. The construction of high panel dam should improve the compaction density of rockfill body as much as possible to reduce the residual deformation of the dam.