The Research Of Expanded Polystyrene’s Application In Municipal Subgrade Overlying Metrotructure

At present,it is difficult to avoid the construction of municipal roads in the subway protection zone.However,in views of the construction of the new bridge-approach section road,its high fill and the soft soil in the lower layer will inevitably cause disturbance to the existing subway structure.The deformation of existing subway structures must be strictly controlled while ensuring the safety of new roads.When conventional subgrade fillers fail to meet the requirements of new engineering,it is increasingly important to adopt lightweight fillers and evaluate the impact of road construction on surrounding structures through finite element analysis.This study is based on rapidness reconstruction project of Weiqi road at Jiangbei district,Nanjing,Jiangsu province.Due to soft soil exists in high fill subgrade in viaduct bridge-approach of the project,the EPS plate material was taken as the filling material of bridge embankment for the purpose of reducing the influence of high fill embankment on the subway and considering the negative impact of the existing road on the construction.Therefore,it is necessary to conduct feasibility analysis and numerical simulation research for EPS plate as fillers of bridge-approach subgrade.In this study,EPS plate was selected as the subgrade filler,the rationality of the selection of EPS plate was evaluated by comparing the advantages and disadvantages of deformation indexes for EPS plate,original lime soil plan and other lightweight fillers through finite element software.This paper mainly discusses the application effect of EPS plate from two perspectives of reducing foundation settlement and reducing disturbance to subway structure.Firstly,the effect of different fillers on the reduction of foundation settlement was compared by the conventional calculation of soft soil subgrade settlement at a bridge-approach.Secondly,the calculation of compressive strength of EPS subgrade,the design of embankment body,the calculation of embankment settlement and the checking calculation of embankment stability were carried out to evaluate the feasibility of the design scheme.Finally,the effects of the fillers on the reduction of the disturbance to subway structures were evaluated by using 2D Plaxis and 3D Midas,and the effects of different replacement depths of EPS plate and other light fillers on the deformation of foundation were compared and analyzed.The results show that the filler has a good effect in views of reducing the influence of foundation settlement and surrounding structures,and the deformation is greatly reduced.But the conclusions obtained by different software are different.In order to verify the above conclusions,the influences of the filler on the road and subway were analyzed based on the relevant deformation observation results during construction and operation,and an equivalent load value evaluating reasonable safe construction was proposed.Finally,the technology and economy of EPS subgrade construction were analyzed,which can be used as a reference for other projects.