Aanalytical and Numerical Analyses on Stiffness Enhancement of Ground Improved by Head-Enlarged CDM Columns

Abstract

This paper presents a comparative study on stiffness enhancement of grounds improved by an innovated CDM method (named Point Foundation (PF)) and by the conventional CDM method using analytical and numerical analyses. The stiffness enhancement is evaluated through induced settlement values under two examined shallow footing cases, of which one is ideally assumed and the other is an actual footing constructed. Results from both analytical analysis and numerical analysis, in which both elastic and elastic-perfectly plastic soil models are used, indicate that in general the PF method produces a more proper stiffness distribution with depth, which in turn results in smaller settlement values. Numerical analysis results also indicate that when only soil area under the footing is improved settlement of the footing is significantly larger than that on ground improved entirely, the case of theoretical elastic soil model. This is attributed to the influence of larger horizontal displacement around the footing.