Analysis of deep excavation with column type of ground improvement in soft clay

To minimize the ground settlement induced by the excavation, the column type of ground improvement has been used in many parts of the world, possibly due to the fact that this type of soil improvement is relatively easily produced and conceptually understood. However, an analysis method and design concept has not yet been established at this time. In this paper, a method for evaluating composite material properties of the treated soil mass is proposed, in which the treated soil area is replaced by a single material during analysis. This allows a three-dimensional analysis to be performed with less computer storage and computation time. Furthermore, a slight modification was made on the method, which makes plane strain analysis also applicable to the column type of soil improvement. The analysis method was supported through a model test and a case history.