Relative contribution of various deformation mechanisms in the settlement of floating stone column-supported foundations

Abstract

Failure mechanisms of single, isolated stone columns are known to include bulging, punching and general shear failure for long, short floating and short end-bearing columns, respectively. Block punching and lateral displacement of edge columns are additional failure mechanisms relevant to groups of floating stone columns. The term “deformation mechanism” is used here to refer to a source of settlement of a stone column supported foundation (SCSF) which, under a sufficiently large load, leads to failure due to the development of a corresponding failure mechanism. The three main mechanisms that contribute to the total settlement of floating SCSFs are considered in this study. Contributions of these mechanisms to the overall SCSF settlement are quantified using settlements at three representative points of the stone column group. A novel chart is introduced to relate values of these contributions to the overall settlement using results of 3D finite element modeling of a large number of SCSFs. Locations of points on this chart for cases with the same governing deformation mechanism are determined and regions related to the various mechanisms are identified. Knowledge of these mechanisms helps determine the design parameters that contribute the most to the settlement of SCSFs and the most efficient way to minimize this settlement.