Stress And Deformation Analysis Of Geosynthetic-encased Stone Column Supported Embankments Based On Cavity Expansion Theory

With the continuous development of roads and engineering construction in China,the composite foundation technology of Geosynthetic-Encased Stone Column?GESC?has widely used.Although there have been many researches on the bearing capacity and settlement of stone column foundation,the assumptions for the initial stress of surrounding soil are isotropic and the effect of vertical stress in the soil is ignored,which is obviously different from the actual situation.How to describe the sedimentary and consolidation characteristics of natural soft soil reasonably,and establish a more realistic analysis model of stress and deformation has become the important and difficult of current research.Therefore,based on the theoretical analysis method,the stress and deformation calculation method of the GESC-supported embankments are studied and discussed in this paper.The main research contents are as follows:First of all,according to the domestic and foreign research status of stone column composite foundation,the reinforcement mechanism of GESC composite foundations and common failure modes are described in detail.The stress-deformation mechanism of the GESC composite foundations under flexible foundations such as embankment is mainly discussed.The calculation ideas for analyzing the actual radial bulging and vertical settlement deformation of based on the cavity expansion theory are proposed.Secondly,based on the theory of cylindrical cavity expansion,the elastoplastic constitutive relationship of the surrounding soil is described by the anisotropic K₀-based Modified Cam-Clay?K₀-MCC?model,analyzing the relationship between the radial stress and the elastic-plastic boundary displacement.Moreover,according to elastoplastic model of stone column,the radial and vertical stresses and deformations are analyzed.The theoretical calculation methods for the radial displacement of the stone column,the vertical settlement of the column top and the displacement of the surrounding soil are derived by establishing accurate balance equations of radial and vertical stresses.Also,the bearing capacity calculation method for the stone column is obtained based on the above radial stress solution.By comparison with existing laboratory model tests,numerical simulation and engineering example,the results indicate that the theoretical methods can accurately and reasonably predict the analysis of the stresses and deformations of the GESC-supported embankments.Finally,the parameter analysis shows that considering the surrounding soil as an elastoplastic model can provide a better accuracy in predicting deformation.As for the isotropic in-situ stress state,the predictions generated from the isotropic model underestimate the deformation of radial displacement and vertical settlement of GESC-supported embankments.