FINITE ELEMENT ANALYSIS FOR OPTIMAL DESIGN OF DEEP MIXED COLUMN FOUNDATION IN HIGHWAY EMBANKMENTS

Composite foundation theories,based on an equal-strain concept between soil and columns in the reinforced area,is commonly used in China to design deep mixed column(DMC) foundations.However,many case studies show that differential deformations between soil and columns in the reinforced area are obvious under the loading of highway embankments.The strength of DMCs can not be fully mobilized.The composite modulus of the reinforced area should be modified for the calculation of differential deformations.Finite element method(FEM) is used in this study to investigate the behavior of DMC foundations under the embankment loading,and a reasonable strength range of DMCs is put forward.Finally a method is proposed to reasonably estimate the modified composite modulus of the reinforced area by considering the degree of mobilization of DMCs.