Incorporating Temperature Effects in Soil-Water Characteristic Curves

Abstract

The study of water movement in unsaturated soils under non isothermal conditions requires understanding the soil water characteristic curves (SWCC) as a function of temperature. Physical processes such as water permeability, and shear strength of unsaturated soils are a function of the SWCC. These curves are generally assumed to be a unique relationship for a soil for all practical purposes. However, factors such as temperature and volume change can affect this uniqueness. The aim of this paper is to present a rational approach to describe the effect of temperature on the SWCC under isothermal conditions. A simple equation based on the relationship between temperature and the capillary rise is applied to find the air entry value at different temperatures when its value is known at a reference temperature. The same equation can be applied to the residual water content term of the SWCC. An experimental procedure for two different coarse-grained soils in the low suction range (i.e., 0–30 kPa) at three different temperatures (4, 20, and 49∘C) were conducted to validate the proposed approach. The comparison between experimental results, published SWCC data from literature and the proposed equation indicate that the proposed method can be used to successfully predict the measured SWCC with respect to temperature.