Towards a dimensionless description of soil swelling behaviour

Soil swelling is a complex phenomenon resulting from adsorption of water onto the surface of clay platelets. It is influenced by procedural, environmental and structural factors. In particular, the initial hydration state of a soil (expressed in terms of saturation degree, water content or suction), its initial level of compaction (expressed in terms of void ratio or dry unit weight) and the level of confinement are among the influencing parameters most studied. Characterising the swelling potential of a soil in the laboratory is an extensive task and tools for prediction are somehow limited. This paper presents the first attempt to use dimensional analysis to predict the amount of soil swelling. This approach makes use of the Buckingham pi theorem to reduce an equation describing a physical phenomenon into an equation involving a reduced number of parameters, which are dimensionless. One of these numbers, called DSP_w, was specifically derived and validated using datasets from the literature. These data were obtained from monotonic one-dimensional swelling tests until full saturation. The results suggest that dimensional analysis and the resulting dimensionless model can be used to predict soil swelling with relatively good accuracy.