An Unconfined Swelling Test for Clayey Soils That Incorporates Digital Image Correlation

Abstract

A new laboratory test apparatus and methodology have been developed for characterizing the swelling potential of expansive soil under free stress conditions. Soil specimens are given access to water under true free swell conditions, and the maximum swelling potential is determined experimentally. Real-time deformation measurements and interpretation are obtained through digital image correlation using GeoPIV. The capabilities of the new test are illustrated using a remolded natural swelling soil. Both primary and secondary swelling behavior were observed during testing. The effect of the aspect ratio was assessed, and it was found that smaller specimens achieved equivalent swelling strains with significantly shorter test durations. The non-contact deformation results agree with the end-of-test hand measurements. The non-contact method also provides additional valuable information regarding the time-dependent swell behavior and evaluation of the end-of-test criterion. The results are interpreted using the Swell Equilibrium Limit, which is a unifying framework for the analysis and prediction of swelling soil deformations under defined initial and boundary conditions.

Time-dependent behaviour of the Bearpaw Shale in oedometric loading and unloading

“…3d, an incremental compression and swelling index can be defined by eqs. [2] and [3] as the change in void ratio over the load increment.…”