汶川地震中小鱼洞大桥的变形破坏特征与机理

摘要

Based on the theory of natural disaster system, the concept of sandstorm disaster risk is expounded, and the composition of the risk is analyzed in three aspects as the danger of disaster-causing factors, the stability of hazard inducing environment and the vulnerability of hazard bearing bodies. The risk assessment indexes of the above-mentioned three aspects are researched according to the composition characteristics of the risk, and the significance of the indexes application in the risk assessment of sandstorm disaster is discussed.%在现场调查的基础上,研究了汶川地震中小鱼洞大桥的变形破坏现象,总结了变形破坏的特点,分析了发生变形破坏的机理.小鱼洞大桥在汶川地震中表现出复杂多样的变形破坏现象,包括梁体塌落,引线段断裂、形成断坎,边坡坍塌,路面纵向拉裂,盖梁与桥台之间右行错动,伸缩缝拉开并发生左行错动和桥台搭板移位等.小鱼洞大桥变形破坏的特点主要表现为挤压与拉张现象并存、左行与右行现象并存和水平向振动与竖向振动并存.地震时小鱼洞大桥受到了复杂的力学作用,不仅有水平挤压作用,而且有竖向和水平向的振动作用以及水平剪切作用.