BEARING CAPACITY OF DEEP FOUNDATIONS IN SATURATED CLAYS

Abstract

The ultimate bearing capacity of the base of shallow or deep foundations in saturated clays is studied using the method of characteristics. The undrained cohesion of the clay is considered to be anisotropic and to increase linearly with the depth below ground surface. Values of the bearing capacity factor, N_c, are presented in terms of the non-dimensional depth of foundation, the inclination of the equivalent free surface to the horizontal, and the parameters defining the anisotropy and the nonhomogeneity of the soil. It is found that, when the vertical strength is more than horizontal strength, lower values of N_c than those for the isotropic case are obtained. Also substantial increase in the values of N_c are found in the case where cohesion increases with depth, as compared to the case of constant cohesion with depth. Further, it is observed that the value of N_q, in the case of an anisotropic and nonhomogeneous medium, may be taken equal to unity without much error.