地震力与共振动水压力综合作用下冰碛堰塞坝失稳机制研究

Instability of moraine dams under the combined action of seismic forces and resonant hydrodynamic pressures

小型库湖中地震产生的水体共振现象是一直被忽视的问题。在我国帕隆藏布流域,即使是小型堰塞湖溃决,仍可能因灾害链效应而形成大灾,但有关地震力与共振产生的动水压力综合作用下的冰碛堰塞湖溃坝机制研究尚属空白。利用大型振动台实验揭示地震动水压力的分布规律;结合弹簧模型,提出水体共振时最大地震动水压力的经验公式;基于极限平衡理论,采用拟动力方法模拟地震力,建立地震振动与共振动水压力综合作用下堰塞坝的整体稳定性分析模型;以川藏铁路拟经帕隆藏布流域为例,比较考虑和不考虑水体共振下35个冰碛堰塞坝的整体稳定性,对小型冰碛堰塞湖溃决进行危险性评估。该研究为小型库湖地震溃决风险预测增加了新认识。

The resonant phenomena occurring in the small reservoir due to the earthquake are always neglected. The burst of a small moraine-dammed lake may trigger the catastrophe because of the chain effect in Parlung Zangbo river basin. Little attention has been paid to the research of moraine dam failure under the interaction of seismic forces and resonant hydrodynamic pressures. The characteristics of hydrodynamic pressures are studied with the large-scale shaking table. An empirical equation using the mass-spring model is proposed to predict the maximum resonant hydrodynamic pressure. The pseudo-dynamic approach is implemented for the seismic force and a new mode for the global stability analysis based on the limit equilibrium theory is established to take into account the seismic force and resonant hydrodynamic pressures. The differences of global stability with and without water resonance are analyzed. The burst risk assessment of 35 small moraine-dammed lakes are completed for Parlung Zangbo river basin.