Dynamic Response Analysis Of Pier Under Impact Of Debris Flow

Debris flow is one of the most common natural geological disasters in mountainous areas.At present,the highway Bridges and other infrastructure construction has expanded to the southwest mountainous area,it is the preferred way in bridge when crossing the debris flow area.So the bridge structures across the debris flow area are vulnerable to be damaged under the impact of debris flow.As the key part of the traffic system,it will lead to serious consequence if it is damaged.In this dissertation,a simple supported beam bridge under the action of a debris flow in southwest mountain area is analyzed.The details are as follows:(1)This dissertation briefly introduces the domestic and international research status of debris flow disaster and its impact,as well as the significance of the research and the main contents of this dissertation.(2)In this dissertation,the basic characteristics of debris flow are briefly introduced.And the related important parameters such as bulk density,flow velocity,flow rate,impact force and impact height of debris flow are discussed in detail whose calculation methods are provided.Moreover,the basic theory of mathematical models and rheological mechanics models of debris flow movement are introduced in detail.(3)Taking the simply supported girder bridge under the action of a debris flows in southwest mountainous area as the research object,simulate the response of the bridge under the impact load by using general finite element software ANSYS,which to show that the main reason of the overall displacement of pier comes from debris flow impact force and pressing point stress increases rapidly under the force effect of the large rock,which results in Stress concentration and maximum compressive stress.The stress of other places of the pier is also mainly produced by the overall impact of debris flow.(4)The basic theory and software of fluid solid coupling are briefly introduced.The three-dimensional turbulence models are described,and the fluid solid coupling control equations are provided.Based on this,taking the simply supported girder bridge under the action of a debris flows in southwest mountainous area as the research object,in the simulation software of ANSYS Workbench environment which has the Fluid Flow(FLUENT),Transient Structural and System Coupling calculation modules,two-way fluid solid coupling calculation under the impact of debris flow has finished.The velocity distribution nephogram,the pressure distribution nephogram,the velocity vector nephogram and velocity trace nephogram of Flow field in different time are obtained.(5)Through the analysis of the results of two-way fluid solid coupling calculation under the impact of debris flow,the displacement,stress and strain of the three different cross section forms bridge pier are compared under the condition of same impact of debris flow.The results show that in the condition of equal in area,circular pier is superior to the rectangular pier,rectangular pier is superior to square pier.Therefore,circular pier is the best form in debris flow areas.