FOOTING CONTACT PRESSURE OF BUILDING FOUNDED ON SOFT CLAY TREATED WITH SAND PILES

Abstract

This research is devoted to the behavior of a separate single footing constructed over soft clayey soil treated with sand piles. The proposed structure is a multi-storey building having bays 4x4 m. Supporting column has large steel I-section resting on a 2.5x2.5x0.40m footing transferring a presumed load of 460kN. Several patterns of sand piles are proposed in soil foundation and each case is analyzed separately to account for the change in shear and moment in footing. The problem is analyzed numerically by the FE technique using STAAD-Pro/2004 program, while the footing is divided into a FE mesh having 100 element of semi-cubic shape. Degrees of freedom at each node are six. The distribution of soil pressure is measured using Hughes theory, which deals with the bearing capacity of sand piles. Soil modulus of subgrade reaction is assumed 20000kN/m².m, angle of friction for sand is 30 degrees, and the undrained cohesion of soft clay is 25kN/m². It is concluded that the presence of sand piles in foundation clay does not have much change in the stresses coming from shear and moment distribution in footing compared to same footing constructed on clay without sand piles treatment. Meanwhile, the ACI code failure criteria are considered valid in both cases.