Development of relationships between swelling and suction properties of expansive soils

Abstract

In this paper, an attempt is made to correlate swelling properties of expansive soils with their suction properties. To achieve this, both swelling, using a conventional oedometer apparatus, and suction, by dew point potentiameter, WP4, properties were measured on different soils used in the study. With the help of data obtained from experimental investigations, plots were drawn against individual swelling parameters (viz., swelling potential, S, swelling pressure, Sp, & free swell index, FSI) vs. suction property like (a) air-entry value, AEV, (b) initial suction, ψi, (defined as suction measured at natural water content that is determined at the time of collection of a soil from the field) and (c) suction measured at optimum water content, ψOMC, in order to develop generalised empirical relationships between swelling and suction properties. It has been observed that AEV and ψOMC exhibits a linear relationship with S and Sp, whereas ψi exhibits a tri-linear relationship with S and a linear relationship with Sp, respectively. The study finds that AEV and ψi, the former parameter is to estimate Sp & FSI, and the latter one is to estimate S of a soil, are the best useful suction parameters to relate them with the swelling properties. Additionally, efforts were also devoted to predicting the swelling properties (viz., swelling potential and swelling pressure) from suction properties by adopting to an artificial neural network (ANN) modelling tool. Overall, the results demonstrate that resorting to suction properties is a quite promising option for predicting the swelling properties of expansive soils.