天然砂砾石料具有级配离散性差、间断性和施工易分离等特性,强震作用下大坝防渗体一旦发生破坏,将会带来不利影响.采用混凝土塑性损伤模型和堆石料广义塑性模型,对弱透水性高面板砂砾石坝进行动力有限元分析,确定面板损伤分布,进而计算坝体非稳定渗流场,建立以混凝土损伤模型和堆石料广义塑性模型为基础的非稳定渗流-应力耦合计算方法,分析在非稳定渗流作用下,大坝应力和变形的变化规律.结果表明:坝体为弱透水时,地震结束后大坝在非稳定渗流作用下,坝体小主应力显著减小,面板产生向上拉伸、向外弯曲趋势的位移增量,面板部分区域损伤值变大.评价大坝极限抗震能力时,除了考虑地震结束时面板的损伤状态,还应进一步考虑面板破坏后非稳定渗流对应力场的影响.%The natural sandy gravel has the characteristics of poor dispersion of gradation ,discontinuity and easy separa-tion of construction ,and it will bring negative effects if the dam ' s anti-seepage body is destroyed under strong earth-quake .In this paper ,the plastic damage model of concrete and the generalized plastic model of rockfill are adopted to conduct the seismic response of the weakly permeable high concrete face sand-gravel dam ,which aims to investigate the damage distribution of concrete slab and the subsequent calculation of the unsteady seepage field in dam body .Based on the two models ,a distinctive coupled unsteady seepage and stress method is established .The variation of stress and de-formation of dam under the action of unsteady seepage is analyzed .The results show that when the weak permeability dam is under unsteady seepage ,the 3rd principal stress of the dam could reduce significantly .The displacement increment di-rection of the slab is upward and outward bending ,and the damage value is larger .It is necessary to consider not only the damage state of the slab after earthquake ,but also the influence of unsteady seepage on the stress field when evaluating the maximum aseismic capability of dam .
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