Efficacy of Utilizing Stress-Dependent SWRC in the Analysis of a Footing Resting on an Unsaturated Soil Slope

Abstract

The response and the safety of geostructures constructed on hilly regions or sloping grounds are receiving increased attention. As the foundation of geostructures resting on slopes is often in the vadose zone, accounting for appropriate properties of partially saturated soil is essential for effective design. Moreover, changes in climatic conditions will adversely affect the load-carrying capacity and the stability of the footing resting on unsaturated slopes. Often, the soil–water retention curve (SWRC) at null stress is adopted but is expected to be affected by various factors, including the stress state of the sample. In the present study, an attempt has been made to demonstrate the effectiveness of using stress-dependent SWRC (SDSWRC) in analyzing a footing resting on a slope exposed to seasonal variations. The SDSWRC along the drying–wetting path determined experimentally was fitted using the standard SWRC model. The key parameters of the SDSWRC, hydraulic conductivity function, and shear strength of unsaturated soils are utilized in numerical modeling. Transient state flux analysis is carried out to mark the effects of SDSWRC in the development of hydraulic response. The stability of an unsaturated slope subjected to a footing load located at a chosen setback distance was assessed under various hydromechanical conditions. The results demonstrate that the seasonal variation, water table position, and net stress significantly influence the stability and the load-carrying capacity of the footing resting on an unsaturated slope.