强震持时对重力坝坝体-坝基整体损伤演化的影响

为分析地震动持续时间对重力坝坝体—坝基整体损伤演化的影响,基于塑性损伤力学理论,综合考虑重力坝坝体—坝基材料非线性损伤,以某重力坝为例建立坝体—坝基整体损伤力学模型,分析不同强震持时下的坝体—坝基体系动态响应及累积破坏规律,并探讨了强震持时的确定方法。结果表明,强震持时对重力坝坝体—坝基体系损伤演化影响明显,强震持时越长,重力坝坝体与坝基产生的损伤累积破坏范围越大;坝体抗震薄弱部位主要位于坝头下游折坡处附近,坝基抗震薄弱部位主要位于坝踵基岩处,且坝基损伤程度大于坝体损伤程度;强震作用下,重力坝坝体—坝基体系产生的塑性耗散能大于损伤耗散能,二者随着强震持时的增加均表现出不可逆的增长。研究成果可为大坝抗震设计提供参考。

Influence of Strong Motion Duration on Damage Evolution of Gravity Dam Body-Foundation System

In order to analyze the influence of the duration of ground motion on the damage evolution of the overall gravity dam body-dam foundation, taking a gravity dam as an example, based on the theory of plastic damage mechanics, considering the material nonlinearity of the system, a damage mechanics model of the overall dam body-foundation system is established to analyze the laws of the dynamic response and cumulative damage of the system under the action of strong earthquakes with different durations. And then the determination method of strong earthquake duration is discussed. The results show that the duration of strong earthquake has obvious impact on the damage evolution of the gravity dam body-foundation system. The longer the duration is, the greater the cumulative damage of the gravity dam body and the dam foundation is; The weak part of the dam body is mainly located near the downstream slope of the dam head and that of the dam foundation is mainly located at the dam heel. The damage degree of the dam foundation is greater than that of the dam body. In addition, under the action of strong earthquakes, the plastic dissipation energy is larger than the damage dissipation energy generated by the gravity dam body-foundation system, and both of them show irreversible growth as the strong motion duration increases. The research results can provide a basis for the seismic design of the dam.