Design Charts and Simplified Approach for the Bearing Capacity of Strip Footings on Sand Overlying Clay

Abstract

Native soils are often deposited in layers. The evaluation of ultimate bearing capacity of shallow foundations on sand overlying clay has been relevant topic. This problem is complex as it is highly dependent on geometric and geotechnical properties of a given soil. Moreover, the conventional methods provide oversimplified approaches, yielding unreliable results. In this study, the bearing capacity and failure mechanism of footings placed on sand overlying clay are evaluated using discontinuity layout optimization (DLO). By introducing a reduction coefficient, a set of design charts that can be directly applied to the classical bearing capacity formulation is presented. A regression-based approach, relevant to a wide range of geometric and strength parameters, is then developed to accurately capture the bearing capacity. The model uncertainty for the proposed method is investigated with the artificial data and results from literatures. The model bias is characterized as a lognormal random variable with a mean of 1.126 and a coefficient of variation (COV) of 0.186.