Upper-Bound Limit Analysis of Bearing Capacity and Failure Mode of Strip Footings Considering Cohesion and Friction Anisotropy

An upper-bound limit analysis is proposed to determine the failure mechanism and bearing capacity of strip footings on soil exhibiting anisotropy in both cohesion and friction. The failure mechanism consists of a series of rigid blocks, whose geometry is sequentially determined using a spatial discretization technique. During the derivation of the failure geometry, the cohesion, friction angle, and discontinuity velocity along each discontinuity surface are calculated rigorously. The ultimate bearing capacity is obtained through the internal energy dissipation and the work rate of external forces. The results of the proposed method are presented for various parameters, including the anisotropic factor and friction angle, with the bedding plane orientation varying from 0° to 90°. Finally, the upper-bound solutions are compared with the results of finite-element simulations and experimental model tests to verify the effectiveness of the proposed method. The study shows that anisotropic shear strength significantly influences the bearing capacity and failure mode of strip footings, and neglecting the friction anisotropy may lead to unreasonable predictions.