numerical study of the settlement of rafts on soft soils improved by small groups of stone columns

Stone column installation is used as an economical, simple, and efficient technique for soft ground improvement to reduce settlements, increase bearing capacity and accelerate the drainage of the foundation soil. while design approaches and analytical methods usually consider the condition of a very large loaded area by using unit-cell models, many practical stone column improvement projects deal with finite or semi-infinite loading areas (e.g. storage tank foundations and road embankments, respectively). in recent years, researchers drew attention to studying the behavior of small groups of stone columns. there are some recommendations in the literature for the prediction of settlements of small groups of stone columns (sgroup) based on results of unit-cell models (suc). however, these methods are developed for a specific soft soil or loading condition. this paper presents a relationship for the estimation of the ratio of settlement of a finite-sized stone column supported foundation (scsf) to the settlement of an infinite group as obtained from a unit-cell model (sgroup/suc). the sub-soil and loading conditions are easily taken into account in the proposed relationship. for this purpose, the settlement of a large number of scsfs having various geometrical and mechanical conditions is investigated using numerical fem modeling.