Bearing Capacity Estimation for Strip Foundation under Transient Flows

A new model was first proposed to estimate the ultimate bearing capacity of strip foundations under transient flows on the basis of the kinematic approach of limit analysis. To describe the collapse process, a symmetrical collapse mechanism was generated by discretization technique following the associated flow rule. A layer-wise summation method was developed to calculate the internal dissipation rate. The theoretical results of this paper are given in terms of some assumptions: (1) both soils and fluids considered in this study were regarded to be noncompressible; (2) the hydraulic conductivity in an unsaturated state was equal to that in a saturated state; and (3) the slope of the soil-water characteristic curve was assumed to be constant through the whole transient infiltration process. A series of comparisons with the theoretical results and experimental data were established to verify the reliability of the new approach proposed by this paper. Based on the numerical results and discussions, the key conclusion can be drawn as follows: the ultimate bearing capacities saw a relatively large decrease under transient flows, especially for strip foundations embedded in silt soil, however, the bearing loads for foundations in sandy soil tended to be steady throughout the whole infiltration process.