Abstract
The finite element method has been used to compute the bearing response of shallow foundations penetrating deeply into non-homogeneous soil, for comparison with classical plasticity solutions. The numerical approach uses remeshing and interpolation techniques, together with conventional small strain analysis. The computed bearing capacity has been compared with lower and upper bound plasticity calculations, based on idealised modelling of the soil conditions around the foundation, for both smooth and rough conditions at the foundation-soil interface. It is shown that classical bearing capacity solutions that ignore the strength contribution of the adjacent soil above the plane the plane of the foundation provide good estimates of the bearing capacity of a foundation penetrated from the surface. This is due to the compensating effect of weak soil trapped beneath the foundation. By comparison, foundations that are pre-embedded show appreciably higher bearing capacity. The effect of local soil heave is also shown to be significant in increasing the bearing capacity of foundations penetrated from the soil surface.
