Soil Water Characteristic Curves from Measures of Electrical Permittivity

As the need for infrastructure increases, so must the understanding of soils under in situ or natural conditions. Soils in in situ conditions typically exist in an unsaturated state. Unsaturated soils exhibit different engineering behavior and responses than saturated soils. Therefore, methods must be developed to predict the behavior of unsaturated soils under in situ conditions. The soil water characteristic curve relates moisture content to matric suction of a soil for a given soil structure and is the primary means used to describe behavior and characteristics of unsaturated soils. Electrical parameters such as electrical permittivity have been used successfully to predict moisture content in soils. However, further research is required to assess if electrical parameters relate to soil suction and thus can become an alternative means to establish the soil water characteristic curve. In this study, correlations were investigated between soil water characteristic curve parameters and measures of electrical permittivity. The permittivity values were analyzed with respect to their variations with matric suction, volumetric water content, and dry unit weight. This study found that both volumetric water content and matric suction can be expressed as a function of the electrical permittivity; thus providing a possible means of determining an insitu soil water characteristic curve.