Upper bound analysis for bearing capacity of nonhomogeneous and anisotropic clay foundation

The bearing capacity calculations for nonhomogeneous and anisotropic clay foundation are often employed the methods of limit equilibrium, limit analysis and characteristic. In this paper, an approach of upper bound theorem in conjunction with new failure mechanism is adopted to estimate the bearing capacity of foundation in nonhomogeneous and anisotropic clays. The proposed failure mechanism is composed of a series of rigid blocks, which is constructed in a manner to respect the normality condition of limit analysis theory at every point of velocity discontinuity surfaces, considering the property of spatially varying materials. Using a spatial discretization technique, the slip surface of failure mechanism is determined point by point. Based on upper bound theory of limit analysis, the internal energy dissipation and the work rate of external forces are calculated for each block. Coding the corresponding computer program, the solutions of bearing capacity of nonhomogeneous and anisotropic clay foundation are obtained. The results are compared with those previously published solutions using the characteristic and limit equilibrium methods. From the comparisons, it is found that the approach of this paper is effective to analyze the bearing capacity of nonhomogeneous and anisotropic clays. Then, the solutions are presented, and the influence of nonhomogeneity and anisotropy on the bearing capacity is discussed.