Influences of rainfall infiltration and hysteresis SWCC of unsaturated soil on settlement of shallow foundations

Abstract

Influences of rainfall infiltration on the settlement of shallow foundations in unsaturated soil were numerically investigated. A computer based finite element analysis using PLAXIS 2D is used to estimate the effects of rainfall infiltration and hysteresis on the settlement behavior of the shallow foundations by incorporating the hysteretic soil-water characteristic curve (SWCC) of unsaturated soils derived from laboratory. There is a good comparison between load-settlement responses and variations in matric suction calculated from the numerical model in the present study were in good agreement with the field measurements. The results of the parametric studies highlight the rainfall intensity played a significant role in the wetting-induced settlement of shallow foundations in unsaturated soil. The wetting-induced settlement during rainfall was also affected by the groundwater table position near the ground surface due to changes in matric suction. In addition, the analysis by a wetting SWCC produced a slight lager settlement up to 5% than that of a drying SWCC. Therefore, appropriate SWCCs (i.e., drying or wetting) is encouraged in the numerical analysis in accordance with the condition that the soils underneath shallow foundations experience.