Numerical Analysis of Ground Reinforced with a Stone Column Group

This paper presents the numerical analyses of a group of stone columns penetrated in a 10 m deep soft clay stratum. A rigid raft transfers the super-structure's loading to the stone columns and the parent ground. The columns group comprises of five columns with a symmetric configuration. The numerical analyses are performed on a plane strain idealization of the structure, using an elasto plastic constitutive behavior for both the stone columns and the soft clay layer. Additional numerical analyses with different range of parameter, like number of columns, space of columns, column’s length, foundation’s size, Poison ratio of soil and stone columns’ material and modulus of elasticity ratio of the stone columns’ material were conducted. The results of analyses showed that lateral displacements (bulging) occur in the upper parts of the columns (between 2D and 4D from the top; D is the column diameter) and the lateral displacements are comparatively higher for the side columns. The major result of the analyses is that for a group of stone columns supporting a rigid raft under spread loading, the lengths of the stone columns could be designed unequal, i.e., inside the columns can be shorter, without significantly increasing of the settlements of the column group. =