Numerical Analysis of Bearing Capacity of Loose Sand overlying Clay

Mohamed Ramadan

Abstract: Soils are often deposited in layers. Within each layer the soil may be assumed homogeneous, although the stress-strain characteristics of the stratified layers are different. The present paper aims to study the behavior of strip footing placed on the surface of sand overlying clay under a vertical central load. The study has been carried out for the bearing capacity of loose sand layer overlying clay soil for the case where the thickness of the sand layer is comparable to the width of a rigid footing. A detailed parametric study was carried out on the bearing capacity of sand layer overlying clay under prototype footings. This study is based on a careful assessment of appropriate combinations of soil properties. The results of the parametric study are used to illustrate the mechanics of the system and also to develop charts that may be used directly in the design. The results are presented in terms of non-dimensional relationships to show the effect of sand thickness to footing width ratio, H/B, and the undrained shear strength of clay layer, cu /?B. In addition, the modes of failure of the foundation soils system are also presented.

Keywords: bearing capacity, sand overlying clay, sand thickness ratio, mode of failure