强余震对主震受损重力坝非线性动态响应的影响

Effect of strong aftershocks on nonlinear dynamic response of mainshock-damaged concrete gravity dams

大量震害实例表明,一次大的主震之后往往会引发大量的余震,而强余震将对结构产生额外的损伤累积破坏。本文中利用能考虑混凝土软化特性并可反映实际损伤耗散的混凝土塑性损伤本构模型,采用Lagrangian算法,考虑库水与大坝和地基之间的动态相互作用,并验证了耦合模型的可靠性;同时对单个主震、单个余震以及主余震序列作用下混凝土重力坝的损伤累积破坏效应进行分析,从大坝损伤、位移响应及损伤耗散能等方面探讨了强余震对主震受损大坝非线性动态响应行为的影响。结果表明,强余震对主震受损大坝的抗震性能具有重要的影响,为此需要提高大坝的抗震性能水平,在大坝抗震设计中应给予重视。

Damages of earthquakes in the past indicate that a large mainshock usually triggers numerous af-tershocks within a short period,and large aftershocks have a potential to cause additional damage to struc-tures. A Concrete Damaged Plasticity（CDP） model including the strain hardening or softening behavior ispresented for the concrete material. Moreover, the interaction between the impounded water and thedam-foundation system is taken into account by the Lagrangian formulation. The validity of the couplingmodel is verified. The effects of single mainshocks,single aftershocks and mainshock-aftershock seismic se-quences on the accumulate damage of concrete gravity dams are presented. The impacts of strong after-shocks on nonlinear dynamic response behavior of the mainshock-damaged dam are discussed in terms ofthe damage,displacement,and damage dissipation energy. The results show that mainshock-aftershocks seis-mic sequences have a significant impact on the accumulated damage of the concrete gravity dam. It is nec-essary to raise the level of anti-seismic property for large dams,to which more attention should be paid inaseismic design of the dam.