Closed-form modeling of matric suction in unsaturated soils under undrained heating

Abstract

Matric suction is an important parameter controlling the hydro-mechanical behavior of unsaturated soils. Several emerging geotechnical and geoenvironmental applications involve unsaturated soils subject to undrained heating. This study presents a closed-form model to determine the matric suction in unsaturated soils under undrained heating. The final expression is derived based upon the Young–Laplace capillary principle and only needs the enthalpy of immersion at the reference temperature and as primary input parameters. Under undrained (constant water) conditions, the closed-form model incorporates the impact of temperature on matric suction by considering the temperature dependency of the liquid–gas interfacial tension, the contact angle of the solid–liquid–gas interface, and the enthalpy of immersion. The model is validated against six sets of experimental data for clay, silt, and sand, reported in the literature. The results show a very good agreement between measured and predicted values for all soil types over a wide range of temperatures. The matric suction monotonically decreases with temperature under undrained heating. The proposed closed-form model can readily be employed in numerical and analytical analyses to simulate the undrained behavior of unsaturated soils under elevated temperatures.