The Dynamic Response Of The Bridge Substructure Under Rockfall Impact

With the tremendous development of the construction of transportation infrastructures at the southwest of China,tons of bridges had been constructed and put in use.Nevertheless,due to the steep cliffs and complex geological condition,rockfall desasters occur frequently,which poses a great threat to the bridges along the highways in mountainous areas.In order to study the dynamic response and damage mechanism of bridge sbstructures under rockfall impact and provide basis for rockfall disaster protection,damage assessment and post-disaster repair,this dissertation carrys out a numerical simulation research on the dynamic response of the bride sbstructures under rock fall impact load.The main work contents are as follows:1.Firstly,assemble the researches of the rock disaster,to summarize the cause,characteristics of the rockfall disaster and rockfall protection methods.Secondly,introduce the experimental and simulation methods ofh common concrete impact problems,study the failure mechanism of concrete under impact load.2.Take an existing bridge in southwest mountainous area as the prototype,use ANSYS Workbench to carry out finite element modeling,use display integral solver LS-DYNA to carry out numerical solution,and then carrying out simulation calculation on the process of rockfall impact on the substructure of the double-column bridge with a straining beam.In the process of building model,discusses the model on the material selection and ultimately choose the CSCM concrete constitutive model,use the key words defined to control the impact contact algorithm and the hourglass deformation,select the proper way of pile-soil interaction modelling and reinforced concrete connection coupling,get a reliable calculation results,the simulation result of the reinforced concrete pier structure model.3.In the calculation process,the damage,displacement and deformation of the pier structure under the falling rock impact are analyzed by modifying the speed and contact position of the falling rock impact.By modifying the structure of bridge piers,the dynamic response of bridge piers with and without tied beams to rockfall impact is compared,the influence of straining beam on the resistance of bridge piers to rockfall impact is discussed.4.After the extraction of the results,the stress and deformation of the bridge pier under the static condition are analyzed,and the damage and dynamic response of the bridge pier under the rockfall impact are analyzed and discussed.5.Based on the simulation results,suggestions are put forward for the protection,damage repair and damage rating method of rockfall disasters.