Numerical modelling of Embankment supported on Cement-admixed Soil Columns surrounded by soft clays

Abstract

Deep Cement Mixing (DCM) columns are majorly used to reinforce foundational support and to curtail settlement of embankment constructed on very soft clays and very loose sands. Influence of DCM columns, with and without a shallow mixing layer, in improving the stability as well as loading capacity of columned improved area subjected to embankment loading is studied by performing FEM analysis and parametric studies on 3D models. Results confirm that columns don’t fail simultaneously but one-by-one starting from the columns near to the centre of embankment. Columns of low strength (i.e. 100kPa) fail by bending and shear, while tension develops in columns of high strength (i.e. 500kPa). Also, as the length of column increases, yield pressure decreases. Furthermore, increment in yield pressure is observed with increment in any of area replacement ratio, column strength or diameter of columns and likewise by the introduction of overlapping in last two columns. Introduction of slab changes the failure pattern of DCM columns from bending to tilting with compression on columns near to embankment centre and tension near column head and slab interface. Slab increases the horizontal resistance of column groups, and slab strength and thickness are directly related with yield strength.