Dynamic Evolution Analysis On The Destroying Action To Bridges By Rock Falls And Collapse

The stability and development of the construction project in the slope has beentroubled by the problem of landslide, which is one of the popular research topic of thegeological disaster. With the rapid development of the domestic civil engineering indus-try, geological disasters caused by the earthquake has been being the threat of the builtand building construction in different degree. Especially in the western region which islocated in the seismic zone and where most of the terrain is the hilly regions, there arelimited ground resources and many buildings close to the mountains. Collapse is a kindof geological disasters with great destruction and randomness. In China it almost makesa large collapse accident causing serious casualties and economic loss every year.At present many scholars research on rockfall impacted roadbed, tunnel and rail-way, and achieved certain results, but little involved in the bridge. In order to analysisthe dynamic response, failure characteristics and weak position of bridge impacted byrockfall, the three dimensional model has been established which helps to make the pre-liminary conclusion on the dynamic characteristics of the whole bridge. On the basis ofabove research, I researched the layout principle of protection system which helps tokeep away the rockfall threaten in mountainous area,and analysed the thought in chaincutting disaster abourt traditional protection technology combined with the chain of cut-ting disaster mitigation methods of disaster chain theory. Reinforcement of the bridgeitself such as adding impact cushion to the pier reduces the impact kinetic energy itself.The following conclusions are obtained through research and analysis:①Reunderstand the predisposing factors of rockfall from rock collapse, divide thelandslide controlling factors into internal and external causes; Analyze the evolutionmechanism of landslide and divide the chain effect of rock collapse into three stages,i.e., incubation stage,creep stage,damage stage.②There are many movement mattern of rockfall such as falling, projectile,throwing, sliding, rolling and the combination of that. There are many factors influen-cing the rockfall trajectory, summed up as the slope angle, slope vegetation, slope li-thology, rockfall shape, size, strength and so on.③In the Study on dynamic response of bridge impacted by rockfall, that is a veryshort concept, test in accordance with the original proportional reduction is very diffi-cult and to reduce the proportion will increase the error, so use the software to simulate it. After a preliminary calculation and analysis of surface: when the bridge deck is im-pacted by rockfall, the entire impact process makes little effect on stress and dis-placement of the internal adjacent span, local effects of rockfall impact loads is moreobvious; when the pier is shocked, it may appear buckling instability which may bringthe collapse of the whole bridge.④With the help of the existing technical measures of protection on the rockfallimpact on tunnel, highway and based on analyzing the relationship between the moun-tain bridge location and collapse body, it puts forward the preliminarylayout principle of passive protection and makes strengthening measures that areadding protective layer on the pier itself,at the same time,it verifies the feasibility ofcalculation by simulation.