The ultimate bearing capacity of an embedded strip footing supported by two-layer c-phi soils has been investigated using an elasto-plastic finite-element computer program. In the program the footing material is treated as linear elastic and the foundation soils are idealized as nonlinear elastic perfectly plastic materials that obey the yield criterion of drucker and prager. The program also considers initial stresses, interface behavior, and tension failure of soil.The analysis was performed on a vax 11/785 computer. Three soils--acommercial kaolin, a silty clay, and a clayey sand--were selected for analysis of a representative number of soil layer combinations. The analysis was performed for a constant footing width and varying levels of top-layer thickness. The propagation of plastic yield zonesunder progressive increments of footing load was investigated, and a generalized procedure for determining bearing capacity from computer-generated pressure-settlement curves was proposed. Meanwhile, on the basis of the analysis results, a semiempirical equation was developed for determining ultimate bearing capacity. A comparison with existing theories indicates that the developed equation can provide more-reasonable results than the existing ones can. Additionally, thedeveloped equation is relatively simple and can be easily applied. This paper appears in transportation research record no. 1331, Integrity testing of foundations 1991
Abstract