Analysis Of Responses Of Mountain Bridge Pier Under Impact Of Debris Flow

Debris flow disasters are widely distributed in the mountainous areas of southwest China and occur frequently,which poses a huge threat to the safety of people's lives and property.With the development of the western region of China,the implementation of the“Belt and Road” and the strategy of a powerful transportation country,roads and railways in the southwest have been constructed on a large scale.Due to the complex terrain of mountainous areas,bridges and tunnels are the most commonly used when highways and railways cross mountainous areas.The proportion of many highways and railways in China even exceeds 70%.Among them,the frequency of the impact of debris flow has also increased year-on-year because of the large number of bridges as spanning structures.When a bridge is affected by a debris flow hazard,the pier is directly affected by the impact of the debris flow,and the external load it receives is huge.If the piers are destroyed,the bridge will collapse and traffic will be interrupted,causing huge economic losses.In this paper,the Wushan debris flow and the highway bridge through the gully are taken as the research objects.By studying the basic characteristics and dynamic characteristics of the debris flow,combined with the basic theory of fluid-solid coupling,and using ANSYS WORKBENCH software,the dynamic response of the bridge pier under the action of debris flow is analyzed Research and propose targeted disaster prevention measures.The specific content and conclusion are as follows:(1)The current status of research on the impact of debris flow at home and abroad is briefly described.Taking Wushan debris flow as the research object,the formation mechanism of debris flow is analyzed from topographical conditions,provenance conditions and water source conditions.The study found that the debris flow belongs to low frequency,heavy rain,and slope debris flow.It is in the development stage.It is rich in loose and movable materials that can participate in the debris flow.The probability of debris flow disasters under heavy rain conditions and other conditions is very high.The main dynamic characteristic parameters of the debris flow are calculated.(2)On the basis of the above analysis and demonstration,the finite element software ANSYS WORKBENCH was used to study the response of three types of bridge piers,namely double-column piers,solid piers and hollow piers in the flow field using the relevant fluid-structure coupling numerical simulation method.In the case of different debris flow velocities,the volume distribution,streamline distribution and base pressure distribution of the debris flow in the three bridge piers in the fluid-structure coupling simulation calculation,combined with the changes in the stress and displacement of the pier,protect the pier Measures analysis.(3)Using the transient dynamic analysis module of ANSYS WORKBENCH software,the response analysis of the pier under the impact load of debris flow was carried out.The main factor of the displacement of the pier is the role of the overall impact force of the debris flow.The impact of large stones will increase the displacement of the bridge piers,and the stress concentration at the impact point of the large stones will increase.In addition to the point of action of the large rock,the stress at other positions of the bridge pier mainly comes from the overall impact force of the debris flow.