【摘要】 本文通过成层状地基地震动输入计算方法得到覆盖层边界自由场运动，采用粘弹性边界，考虑地基辐射阻尼效应及坝体和地基的接触非线性，针对强震区深厚覆盖层场地重力坝开展线性和非线性动力时程分析研究，结合需求能力比DCR评估其抗震性能。由线弹性动力时程分析可知，在运行基准地震OBE作用下，重力坝坝体应力均在允许范围内，其抗滑稳定安全系数不能满足要求；由非线性动力分析可知，在OBE和最大设计地震MDE作用下，重力坝发生较大滑动位移。通过在重力坝坝体下游坝后回填土加强重力坝抗震稳定性，结果表明，下游坝后回填土可有效减小坝体滑动位移，加强其抗震稳定性。本文针对深厚覆盖层场地重力坝开展的抗震安全研究为抗震设计提供了科学依据，为强震区深厚覆盖层场地重力坝的抗震分析提供参考。更多还原

【Abstract】 Based on the method for calculating the seismic input of a layered foundation, the free field motion is obtained. The viscoelastic boundary is adopted to consider the radiation damping effect and the contact nonlinearity between dam and foundation is considered. The linear and nonlinear dynamic time history analysis of a gravity dam in strong earthquake area is carried out, and its seismic performance is evaluated based on demand capacity ratio. The linear elastic dynamic time history analysis shows that the stress of gravity dam body is within the allowable range under OBE, while its seismic stability safety coefficient cannot meet the requirements; the nonlinear dynamic analysis shows that under OBE and MDE, the gravity dam appears obvious sliding. Furthermore, the backfill behind the gravity dam downstream is considered to enhance the seismic stability of the gravity dam. The results show that the backfill behind the downstream dam can effectively reduce the sliding, and enhance its seismic stability. In this paper, the research on seismic safety of the gravity dam under overburden site provides a scientific basis for its seismic design, and also provides a reference for seismic analysis of gravity dams under overburden sites in strong earthquake area.更多还原