Abstract:The end bearing capacity of pile based on Mohr-Coulomb strength criterion does not consider the effect of intermediate principal stress,so that the calculated bearing capacity may be rather different from practical data. This paper recommended a method to determine the end bearing capacity of pile in sandy clay by double-shear slip-line theory,which can consider the difference between the tension strength and compression strength of soil material. The effect of intermediate principal stress was included in the formula,which was based on some reasonable hypotheses. It was developed in a way similar to that proposed by A. Serrano and C. Olalla in the determination of end bearing capacity of pile in rock foundation according to the theory of plasticity. In the calculation process,the plastic area was analyzed as a two-dimensional medium using the slip-line method. The overburden pressure,which was assumed to be uniformly distributed,exerted on the virtual surface(boundary 1),together with the potential external loads that are rested upon it. And then,the stress on boundary 2 was obtained from the stress on boundary 1 by using transferring formula of slip-line. Analyses of the project data collected in the area of Wuhan City were carried out with Mohr-Coulomb strength criterion and the recommended method separately. The results show that the recommended method,in which the effect of intermediate principal stress was considered,was closer to the actual projects. So this method for calculating the end bearing capacity is found to be more useful.