Three-Dimensional Soil–Water Characteristics Model of Expansive Soil Considering Swelling Effect

Abstract

In nature, expansive soil is generally in a state of swelling during rainfall, and its soil–water characteristic curve (SWCC) exhibits a three-dimensional space shape under the action of an increasing void ratio. In this study, expansive soil from Hefei, China, was used. SWCC and hygroscopic tests were performed. A three-dimensional hygroscopic swelling mathematical model of the dry density–void ratio–saturation degree was constructed based on the volume change behavior of expansive soils resulting from the hygroscopic test. In addition, depending on the variation in suction with the saturation degree of expansive soil under different values of dry densities, an SWCC mathematical model considering the swelling effect was constructed. The three-dimensional surface model of the hygroscopic swelling of the expansive soil was steeper in the lower saturation degree area. As the saturation degree increased, the three-dimensional surface gradually became flat. The SWCC model of the expansive soil under the action of swelling in a three-dimensional space is an S-shaped surface. The model exhibited dynamic changes in the suction and saturation degrees as the dry density of the soil decreased continuously. The model comprehensively revealed the hydraulic and swelling properties of expansive soil.