【摘要】 地震主震发生之后通常伴随余震。多次地震下结构的损伤破坏累积效应明显,只考虑主震的重力坝抗震设计是不完善的,应考虑整个地震序列的影响。采用塑性损伤力学对重力坝进行非线性动力分析,揭示了主余震型地震序列下的重力坝损伤演化特征和结构能量耗散机理,通过包含能量特性的大坝定量损伤指标评价了余震作用对结构安全性的影响。实例分析结果表明:主震和余震阶段,重力坝动力耗散能均以阻尼耗散能量为主,混凝土塑性耗散能次之,损伤耗散能所占比例最小;从损伤评价指标看,余震阶段重力坝的损伤主要体现在坝体中上部损伤区域的进一步扩展演化;余震作用使坝体塑性变形较单一主震作用下显著增大,从变形控制的角度,设计中需考虑包含余震波的地震序列对结构抗震安全的影响。更多还原

【Abstract】 Earthquake has the character of cluster with many aftershocks after the main shock.The effect of the whole seismic sequence on the dynamic characteristic of gravity dam should be considered.Damage evolution effect of the dam is analyzed under the experience of different mainshock-aftershock seismic sequences by plastic damage mechanics method based on the energy equivalent principle,the damage evolution role and energy dissipation mechanism of the dam are revealed,and also the damage level of the dam is described by seismic damage assessment model considering damage energy dissipation.The example shows that,the vibration energy and the earthquake responses of the structure are reduced effectively by the structural damping;little amount of the seismic energy is dissipated by concrete damage and plastic dissipation;the damage of the middle and upper part of the dam is the main damage of the structure under aftershocks.It is the aftershocks which make plastic deformation of the dam increase significantly,so that the influence of the whole seismic sequence which contains the aftershocks should be considered.更多还原