Feasibility Study On Widening And Reconstruction Of A National Highway In Zhejiang Province And Finite Element Analysis Of Subgrade Reinforcement

With the rapid development of China's social economy and the gradual improvement of masses' living standards,the per capita automobile ownership has been increasing.Especially in Zhejiang,expressways and provincial highways are congested every legal holiday.In order to satisfy the masses' desire for high-quality life and improve their sense of acquisition and happiness,the sate has intensified efforts to widen and transform the existing important highways and provincial highways in recent years.Highway widening and reconstruction projects need to go through many stages from project establishment to completion,the most important of which is the feasibility study stage,which determines the future construction scale,overall investment and capital construction plan of the project.As the programmatic content of the project construction,it is particularly necessary to do a good job in the feasibility study of the project.Based on the rebuilding project of 320 National Highway Hangbu to Changshan section,this paper studied the feasibility of the project through traffic volume analysis,construction scheme design,investment estimation,economic evaluation,environmental impact analysis and other aspects.At the same time,on the basis of further thinking,this paper puts forward several diseases that often appear in widening and rebuilding of highway,such as cross-slope change,longitudinal cracking,local cracking,new roadbed instability,etc.,and analyzes the causes and treatment techniques.In view of common diseases,this paper proposes to use geogrid to reinforce the old and new roadbed.Through the finite element software tool PLAXIS,the geometric models was estabilished,the working conditions were calculated and simulated,the influence of reinforcement and non-reinforcement on the settlement and deformation of roadbed was analyzed.The final calculation results showed that in this project,the reinforcement can not reduce the vertical displacement and horizontal displacement of the roadbed very well,but compared with the unreinforced roadbed,the stability of the reinforced roadbed was obviously improved.At the same time,when laying a single layer of geogrid,the effect of geogrid at the base of the road was better than at the top and middle of the road.It is hoped that this study can provide reference for the widening and reconstruction of the similar highways.