拱坝-库水相互作用的振动台破坏试验研究

Experimental study on impact of dam-reservoir interaction on dynamic failure mechanism of arch dam

为探究拱坝-库水相互作用对拱坝强震失效模式和超载能力的影响,在振动台上开展模型动力破坏试验。基于弹性力-重力相似律设计模型,考虑了材料率效应,利用天然水模拟库水,缝的模拟考虑了键槽影响以及裂纹尖端开裂相似条件。选择模型基频对应的谐波逐级加载开展超载试验,并运用多种技术手段监测模型损伤破坏全过程。试验表明,库水的预压作用能够充分发挥拱结构的抗压特点,使得顶拱拱向应力分布均匀。本次试验与不考虑库水的研究结果对比,得出结论:库水并没有降低拱坝结构整体超载能力,在宏观裂纹出现前约束顶拱动态应力的发展,使得顶拱与拱冠梁趋于同时破坏。本文研究结果可为评估坝库相互作用对拱坝超载能力与失效模式的影响提供试验依据。

In order to study the impact of dam-reservoir interaction on overload capability and failure mode of arch dam,a dynamic rupture test was carried out on the shaking table.The model was designed on the basis of elasticity-gravity similarity law,taking the material rate effect into account,and natural water is used to simulate the reservoir water.The effect of key grooves were considered in the simulation of contraction joints,while the simulation of induced joints was based on fracture mechanics.Sine waves corresponding to fundamental frequency loaded on the dam progressively to observe the responses of arch dam under overloading.Various techniques were used to monitor the whole process of model damage.The results show that the pre-compression of the reservoir water can fully exert the compression characteristics of the arch structure,making the arch stress distribution at the top of the arch dam.Compared with the research results without considering the reservoir water,this experiment concluded the reservoir water does not reduce the overload capacity of the arch dam.Before the appearance of macro cracks,the development of the dynamic stress of the top arch is restricted,which made the top arch and crown at the same time destruction.The research results in this paper can provide experimental basis for evaluating the impact of dam-reservoir interaction on the overload capacity and failure mode of arch dams.