Research On The Pile-slab Structure To Deal With The Problem Of Vehicle Bumping At Bridge Head

Large settlement difference between the bridge abutment and the subgrade at the road-bridge connection causes bridgehead jumping,which happens frequently in the road-bridge connected sections of soft soil roadbed.Bridgehead jumping not only raises highway operating and maintenance expenses,but also compromises traffic safety.Therefore,taking reasonable and effective measures to avoid and solve bridgehead jumping is important.Pile-slab structure has many advantages,including high structural stiffness,good ride comfort,small post-construction settlement,and suitability for assembly construction.This thesis takes the pile-slab structure as a method to address road bridgehead bumping,and examines its applicability,numerical modeling,and dynamic response.The potential of a pile-slab structure in minimizing vehicle jumping at the bridgehead has been investigated.The following are the specific research contents:(1)Based on the actual engineering geological parameters,the calculation models of natural foundation,cement mixing composite foundation and pile-slab structure foundation are generated in Midas GTS NX finite element program.This thesis analyzes the settlement of three kinds of roads.The results show that compared with natural subgrade and cement mixing composite foundation,the pavement with pile-slab structure has better reinforcement effect and can better prevent bridge jump.(2)A finite element model of the transition section of road and bridge with pile-slab structure is established in Midas GTS NX finite element software.The impacts of pile’s cap plate thickness,length,diameter,modulus of elasticity and spacing between pile on the vertical settlement of subgrade and pile-soil stress ratio are analyzed.The findings reveal that length,diameter,modulus of elasticity and spacing have obvious impacts on the settlement of pile-slab subgrade,where cap plate thickness,length,diameter,modulus of elasticity and spacing can influence pile-slab structure roadbed’s pile-soil stress ratio.Although increasing platform plate thickness cannot make roadbed settlement more noticeably,it can increase the structure’s internal force.(3)The dynamic analysis model of the transition section of road and bridge with pile-slab structure is established in Midas GTS NX finite element software.The dynamic responses of pile-slab structure subgrade under various vehicle loads and driving speeds are investigated.The findings reveal that vehicle loads and driving speed have a noticeable influence on pile-slab structure subgrade.