Research On Influences Of Road Construction And Heavy Trucks Passing Underneath Bridge On Performance Of Piers

During the operation of existed bridge,the adverse effects of nearby large-scale engineering activities will be reflected in the bridge structure through pile-soil interaction.In serious cases,even the displacement of the top of the pier is too large to affect the safety of the bridge.Based on the engineering background of transportation of dregs under a continuous girder bridge in the reclamation area,this paper studies the performance of piers during the construction and operation(during the passage of heavy-duty vehicles)of temporary roads below bridge,discusses the deformation mode and main Influencing Factors of piers,and puts forward pier protection measures,which provide a reference for ensuring the safe use of bridges in similar engineering applications.The main research work and results are as follows:A three-dimensional finite element model of pier-pile-soil is established by ABAQUS,and it is taken as the research object in this paper.The classical elastic foundation reaction method in the "passive pile" problem is used to solve the same conditions of pile foundation.Then the correctness of the model is verified by comparing the simulation results with the theoretical results.The influence of construction of temporary road under bridge on the deformation of pile foundations and pier columns are studied.According to the sequence of Engineering activities,temporary road construction is divided into two stages: soil excavation and pavement filling.In the stage of excavation,the deformation law of pier under unilateral unloading is obtained,that is,the pile foundation deflects to the direction of the proposed road and the pier column deflects from the direction of the proposed road,while the pier vertical slightly floats.In the pavement filling stage,under the unilateral loading,the pile foundations and pier columns have the opposite deformation with the soil excavation stage,while the pier vertical has a slight subsidence.In the operation stage,the influence of the change of speed,weight and spacing of heavy-duty traffic flow on the deformation of pile foundations and pier columns are considered by the control variable method.The results of finite element simulation show that the speed of vehicle has little effect on the deformation of pile foundation and pier columns,and the weight and spacing of vehicle have some influence on the deformation of pile foundations and pier columns.This paper puts forward the measures of isolation and protection of the pier by adding steel sheet piles in the three-dimensional finite element model.By comparing the simulation results of reinforced and unreinforced conditions,it is found that the addition of steel sheet piles has better restraining effect on the horizontal deformation of pile foundation within a certain buried depth and pier columns,the influence is very weak for vertical deformation.according to the monitoring report of pier top horizontal displacement,the simulation results are compared with the actual monitoring results,which verifies the necessity of pier protection measures.