Experiment And Numerical Studies On The Performance Of Pile-supported Reinforced-earth Wall For Embankment Widening

With the rapid development of national economy,part of the twin four-lane expressway built on soft soil is in urgent need of broadening.Therefore,the pile-supported reinforced-earth wall should be transported out as a kind of widening structure with less land resourse,lower cost of foundation treatment and less demand for filler.In this thesis,the performance of pile-supported reinforced-earth wall is studied by centrifugal model test and numerical simulation.The main research contents and achievements are as follows:（1）Based on the centrifugal model test,the working performance of pile-supported reinforced-earth wall on soft foundation soil is analyzed.The differential settlement of new and old subgrade,the mechanical and deformation characteristics of pile foundation and grid,and the deformation and failure trend of widening subgrade are obtained.The results show that the settlement at the junction of new and old subgrade is the largest after widening.And the failure mode of retaining wall is different in the two cases of existing subgrade with and without piles.（2）Through the centrifugal model test,the pile-supported reinforced-earth wall and the pile-supported reinforced subgrade are used respectively in the existing subgrade with and without piles.The advantages and application scope of the pile-supported reinforced-earth wall are obtained.The results show that the pile-supported reinforced-earth wall is widened on the foundation soil under the existing subgrade slope which has completed most of the settlement.Compared with the pile supported reinforced subgrade structure which has not cut slope and built the widened subgrade on the original foundation soil,it has greater stability.（3）By using finite difference software FLAC^3D,the numerical simulation of widening expressway by pile-supported reinforced-earth wall on soft soil foundation is carried out.By changing the length of pile,the spacing of pile and the cutting ratio of slope,the subgrade deformation and failure rules under different parameters are obtained.It can provide reference for the selection of parameters in engineering practice.