Assessing internal stress evolution in unsaturated soils

Abstract

Internal stresses in soils evolve as a result of the various interactions among soil particles and the pore fluids in response to natural or human‐induced activities. Whether attributed to suction, structure, or the various physicochemical forces that may develop, assessing the internal stresses in soils has been an active area of research in soil science and engineering. This paper presents the restrained ring method as an experimental tool for measuring the stresses that develop in a drying soil when it is restrained from shrinking freely. The internal stress that develops can be related to the water content of the soil. This method is validated using results for both silty clay loam and clay loam soils. Tensile stress at failure (estimated from the restrained ring method) was compared to tensile strength ranges of similar soils, and a good correlation was observed. Moreover, internal stresses measured by the restrained ring method were compared with existing empirical relationships (using suction and degree of saturation). This comparison concluded that suction is not the sole contributor to the soil's internal stress.