Model footing tests on unsaturated soils

Abstract

Matric suction increases the shear strength of soils by increasing the apparent cohesion. Foundations placed on unsaturated soils would therefore be expected to have higher bearing capacities than those placed on the same soils in the saturated state. In order to quantify the increase in bearing capacity arising from matric suction, laboratory tests involving the determination of the failure loads of model footings placed on homogeneous soils subjected to different levels of matric suction were carried out. The results indicated a significant increase in bearing capacity with increasing matric suction and compared reasonably well with theoretical predictions based on independently measured values of ϕb and a modified Mohr-Coulomb failure criterion.