Behavior of Rigid Footing Rested on a Group of Stone Column

Raft foundation often adopted for structures constructed on highly compressible soil. Sometimes raft footings are preferred on stone column-improved ground. The current FEM-based numerical study investigated the behavior of a rigid square footing model resting on the surface of a soft ground improved with a group of stone column. To analyze the behavior of the rigid footing, a group of fully penetrating stone columns was constructed beneath the rigid footing. Various parameters such as area replacement ratio, column spacing and relative position of column have been studied. Performance of rigid footing enhances with the increment of area replacement ratio. Bearing capacity improvement was found to be higher at lower settlement level. And a better settlement improvement was observed when footing is acted upon by a higher loading. For larger size raft footing, stone columns arrangements have a significant effect on load-settlement behavior. When stone columns are placed near to the center of the footing, it shows a better improvement in term of settlement and load carrying capacity. A single stone column of equivalent area ratio constructed at the center shows similar behavior as a group of stone column. Different types of failure mechanism were observed for the stone columns placed at different position. Stone columns constructed near the edge of the footing failed by the combined action of bulging and buckling. Whereas, central columns mainly failed by bulging near the top.