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 footingconstructed over soft clayey soil treated with sand piles. The proposed structure is a multistoreybuilding having bays 4x4 m. Supporting column has large steel I-section resting on a2.5x2.5x0.40m footing transferring a presumed load of 460kN. Several patterns of sand pilesare proposed in soil foundation and each case is analyzed separately to account for the changein shear and moment in footing. The problem is analyzed numerically by the FE techniqueusing STAAD-Pro/2004 program, while the footing is divided into a FE mesh having 100element of semi-cubic shape. Degrees of freedom at each node are six. The distribution ofsoil pressure is measured using Hughes theory, which deals with the bearing capacity of sandpiles. Soil modulus of subgrade reaction is assumed 20000kN/m2.m, angle of friction for sandis 30 degrees, and the undrained cohesion of soft clay is 25kN/m2. It is concluded that thepresence of sand piles in foundation clay does not have much change in the stresses comingfrom shear and moment distribution in footing compared to same footing constructed on claywithout sand piles treatment. Meanwhile, the ACI code failure criteria are considered valid inboth cases.