THE EFFECT OF LATERAL CONFINEMENT ON THE SETTLEMENT CHARACTERISTICS OF SHALLOW FOUNDATIONS ON SAND

Today, most of the high rise buildings consist of basements as part of the substructure. Basement construction is usually supported by embedded type retaining walls such as secant pile walls or diaphragm walls. This provides lateral confinement and the performance of shallow foundations would be affected by this lateral confinement. In this study, the effect of lateral confinement on the settlement characteristics of shallow foundations on sand was studied experimentally and numerically. First, experimental investigation using small-scale laboratory models were carried out and the results were used to validate the finite element (FE), model. Changing the depth of lateral confinement and the distance to the edge of the shallow foundation from the lateral confinement, the stress immediately below the footings corresponding to a settlement of 25 mm was compared. Furthermore, the effect of lateral confinement due to embedded retaining wall on the settlement characteristics of a raft foundation on sand was also studied using the validated finite element model. In scaled physical models of confined foundations, there was an enhancement in allowable bearing capacity at the tolerable settlement with the increase in depth of embedment and the reduction of distance to the confinement. It was observed, for the study variables considered in this study that the bearing capacity can be improved up to 4 times by laterally confining the footing. However, in the analysis of confined raft foundations on sand, there was no significant change in bearing pressure for a 50 mm tolerable settlement with the change of study variables.