Settlement Analysis Of Soft Soil Subgrade And Drainage System Design In Old Road Widening

With the rapid development of the national economy,highway construction has entered the fast lane of development,and the mileage has been continuously increasing.At the same time,the service level and capacity have also been continuously improved;however,at the present stage,with the acceleration of urbanization,the roads built in China at the end of the last century tend to be saturated,and most of the original roads belong to the four-lane roads,which have a significant restrictive effect on economic development.Therefore,it is imperative to expand and rebuild them.However,in the process of widening and rebuilding,due to the differences in the construction time and treatment methods of new and old roadbeds,different levels of differential settlements will appear in the new and old roadbeds after widening and reconstruction.At the same time,the unreasonable drainage design will endanger traffic safety and reduce the service life of the roads.Therefore,this paper mainly researches and analyzes the settlement of old soft clay roadbed and the design of drainage system.First of all,this article relies on the widening and reconstruction project of the Gu Shen Road in Zhongshan City,and conducts research on domestic and foreign relevant data and literature,and analyzes and summarizes the topographic and geological data of the area where the project is located.The results show that the main problems facing the reconstruction and expansion of old roads are: The settlement of soft soil roadbed,the liquefaction of saturated sand,the stability of the foundation pit slope of the subsidence road,and the soft soil earthquake subsidence under the action of seismic forces.Secondly,combining with the old road to broaden the actual project conditions,this paper used the finite element software ABAQUS to establish an analysis model for the pile foundation retaining wall and widened pile foundation treatment model,The distribution of internal forces in the treatment of soft foundation structures and the influences on the stability and settlement of subgrade are studied.The calculation results show that the retaining wall of the pile foundation significantly improves the stability of the subgrade,but has little effect on the settlement of the subgrade;The effect of widening the soft soil foundation in the new roadbed with different lengths of piles is more significant than that of the pile spacing.When the pile spacing increases to a certain level,the subgrade settlement does not change substantially.Finally,relevant calculations are carried out for the drainage capacity of the old roadbed in the widening project.The original roadbed and pavement drainage capacity basically meet the design requirements,and the principles and methods for widening the drainage design of the old road are summarized and analyzed.The specific layout method for the drainage design of the roadbed and road surface is proposed under the conditions of checking and satisfying the discharge conditions.The research results can provide reference for broadening the design of soft soil roadbed structure in the future.