Analysis On Differential Settlement Of Widening Subgrade And Its Influence On Pavement Structure Stress

With the increasing demand for highway traffic,widening the already running highways and increasing the number of lanes to improve traffic capacity have great practical significance for highways with heavy traffic loads.This will not only make full use of existing resources,but also save road construction land.After the subgrade is widened,the differential settlement of the old and new subgrade and the deformation problem seriously affect the use effect of the future expansion of the road.Therefore,based on the difference settlement between the old and the new subgrade,the subgrade settlement of the new and old subgrade settlement deformation law is analyzed and the effect of its control technology is analyzed.In this paper,by establishing the ABAQUS finite element analysis model of subgrade widening,the subgrade deformation law of new and old subgrades is simulated and stored for several years.A more comprehensive analysis of the widening method,subgrade width,subgrade height,subgrade soil and foundation soil parameters,subgrade filling rate on the deformation of the subgrade.The study found that the double-sided widening has obvious advantages compared with the differential settlement and horizontal displacement of the single-side widened subgrade.The settlement curve of the top surface of the double-sided widened subgrade has a small settlement at the center of the old road and the largest settlement near the shoulder of the new road.The soft soil foundation height and compression modulus have a significant impact on the uneven settlement between the old and new subgrades.In addition,the finite element models of slope cutting and excavation steps,light soil widening subgrade and geocells laid on the steps are proposed to treat the uneven settlement of new and old subgrades,and the settlement and horizontal displacement of new and old subgrades are analyzed.The study found that the old road slope cutting and excavation steps can not reduce the settlement of the subgrade and the horizontal displacement of the surface.The main consideration is the combination of new and old subgrade and convenient construction.Both light soil embankments and geocells can effectively reduce differential settlement and lateral displacement of subgrade.Finally,based on the uneven settlement deformation characteristics of the widened subgrade,the force analysis of the pavement structure is carried out,and the stress characteristics of the asphalt pavement structure under the differential settlement of the new and old subgrade and the influencing factors of the additional stress of the pavement structure are analyzed.The calculation formula of the additional stress of the uneven settlement pavement structure under the comprehensive influence of various factors is established,and the design method of the expanded pavement structure considering the uneven settlement of the new and old subgrade is obtained.