The changes in stress regime during wetting of unsaturated compacted clays when laterally confined.

Compacted clay fills are placed in an unsaturated condition and over time the fill will become saturated if the water table rises. The bimodal pore size distribution often prevails in these soils. This will lead to a combination of aggregate swelling and collapse during wetting, which can considerably change the stress regime in the fill. This paper examines the stress regime within compacted fills during wetting when lateral expansion is restricted. A one dimensional consolidation chamber was used to examine the behaviour of kaolin compacted to differ-ent initial bulk densities, representing un-engineered fill, engineered fill and heavily engineered fill. Wetting was performed under overburden pressures of 25 kPa, 50 kPa and 100 kPa. High lateral pressures and sample swelling were observed, which have significant implications on the stress distribution behind retaining struc-tures where compacted clays are used as backfilling materials.