Using the FLAC algorithm based on Lagrangian explicit finite difference method

numerical analyses are made on ultimate bearing capacity and failure behavior of strip footings and circular footings founded on nonhomogeneous clays foundations in which soil cohesion increases linearly with depth. Numerical results show that: (1) foundation failure area much more centralizes in surface layer and around footing sides as nonhomogeneous factor kB/c0 increases; (2) bearing capacity are estimated very conservatively if foundation nonhomogeneity is ignored even if kB/c0 is low; (3) bearing capacity factor of footing nonlinearly increases with kB/c0 and interface characteristic of footing and soil has less influence on the bearing capacity shape factor of circular footings except for the homogeneous foundation. Compared with numerical results

it is found that the approximate equations of Skempton and Peck et al. obviously overestimate bearing capacity factor Nc0 for nonhomogeneous soils.