Study On Bridge Head Jump Problem Of CFG Pile Net Composite Foundation Treatment

The uneven settlement between highway and bridge will lead to high-frequency vehicle bumping at bridge head,threatening highway facilities and traffic safety.The fundamental reason for vehicle jumping at bridge head is the huge stiffness difference between bridge and culvert structure and subgrade.The settlement of highway subgrade is greater than that of bridge and culvert structure,which causes the dislocation of abutment at the junction.Because the CFG pile net has the advantages of small settlement deformation,easy control of post construction settlement and reducing project cost,this paper uses the CFG pile net composite foundation to deal with the vehicle bump at the bridge head.Pile net composite foundation is a kind of foundation treatment form in which pile,reinforcement and soil act together to bear the load.It has many functions such as pile,cushion,drainage,reinforcement and protection.However,the mechanism of pile net composite foundation needs further research:At first,this paper analyzes the basic meaning and composition of CFG pile net composite foundation,understands and is familiar with the action mechanism,design parameters,settlement calculation method and construction technology of each part of the pile net composite foundation.The fixed finite element model of the pile-mesh foundation was created using MIDAS GTS NX finite element software by varying the pile spacing parameters,pile diameter,pile length,modules The influence of these parameters on subsidence,axial force and the relationship of pile-to-earth stress is explored at the net composite base of the pile.Some aspects for different parameters are given.The finite element software MIDAS GTS NX is used to establish the dynamic response analysis model of CFG pile net composite foundation under the action of i MPact load of different vehicle loads and driving speed.The analysis shows that the vibration response of different road positions under the action of i MPact load has a great difference,and the vehicle load and driving speed have a relatively large i MPact on pile net composite foundation.