New and Simple Equations for Ultimate Bearing Capacity of Strip Footings on Two-Layered Clays: Numerical study

In this paper, two very simple and accurate equations are introduced that enable geotechnical engineers to determine the undrained ultimate bearing capacity of shallow strip foundations resting on two-layered clays. Results of the analyses show that in the case of weak-over-strong clay, usually general shear failure occurs, and in the case of strong-over-weak clay, the soil will most likely experience punching failure with a large amount of plastic settlement before it reaches its ultimate bearing capacity. This study applied the finite-difference method using a computer program to evaluate the undrained bearing capacity for all cases analyzed. The Mohr-Coulomb failure criterion was used for modeling the plastic behavior of soil. Simple equations are presented for cases of both strong-over-weak clay and weak-over-strong clay representing the bearing capacity of shallow foundations resting on two-layered clays. Results of this study are verified by acceptable statistical methods, and advantages of the presented equations in this paper are discussed.