Study On The Performance Of Buried Road Debris Flow Readiness Bridge

The highway in the west of China is threatened by debris flow,when the rainy season comes every year from six to October.By using the method of dredging on the traditional large debris flow buried body clearance time is long,it will interrupt the traffic for a long time,delay the best time of emergency rescue and disaster relief,affect the life safety in the body and property of residents along the people.In this paper,the development of a debris flow can be set up in the newly buried body can be freely disassembled traffic emergency readiness bridge,due to debris flow compressibility,high water content,low shear strength,consolidation time etc.The combat readiness pontoon bridge is composed of three parts: the bridge cross section,the shore structure and the lateral anchoring device.Among them,the bearing pier of the bridge cross section is the core of the emergency handling technology of the whole bridge.The combat readiness bridge as the research object,this paper uses the structural dynamics theory of elastic thin plate,finite element analysis,material mechanics theory,under the condition of different assembly readiness pontoon bearing capacity analysis,provide a theoretical basis for the erection of concrete road bridge readiness buried debris flow.The main achievements of this paper are as follows:(1)Based on the stress analysis of the pier,the vertical stress is discussed.The debris flow of supporting bearing capacity of pier two parts by the liquid bearing capacity of buoyancy and solid phase composition.Furthermore,the lateral stability analysis of the pier is carried out to determine the optimal height of the stable device 0.8m.(2)Because of the different connecting ways of the longitudinal connecting rod,the combat readiness pontoon bridge can be divided into three types: simple support system,rigid connection system and articulated system.Based on the theory of structural dynamics,elastic foundation beam method and focus ratio method,the stability analysis of three kinds of connection system for the tactical pontoon bridge is carried out.The bearing capacity of the bearing pier,the longitudinal slope of the suspension bridge and the bending resistance of the connecting rod are analyzed.The formula of the maximum settlement displacement of the bearing pier and the formula of the maximum moment of the middle span of the floating bridge are deduced.(3)Based on the K630 debris flow silting road section project,established three kinds of connection system of bridge model readiness by finite element software ANSYS.From the two aspects of the overall displacement of the floating bridge and the flexural performance of the connecting rod,the stability of the three kinds of connection system for the operational pontoon bridge is discussed.(4)Under the condition of the same external effect,the transition points of different connection systems are compared from the aspects of the whole settlement displacement and the force of the connecting rod.Then,the applicable conditions of three kinds of connecting systems are determined.The theoretical basis is provided for the selection of the connection mode of the floating bridge.(5)The finite element model of the different connecting forms of 2m,3M and 4m under the span of three bearing piers is established.Analysis of the influence of bearing pier span on the stability of the bridge with different connection forms.And then provide the theoretical basis for the selection of the span length of the bridge pier.