Consolidation behaviour of a desiccated expansive soil

Yield stress is one of the most important properties of soils. This paper addresses the yield stress of a desiccated expansive soil that was subjected to repeated cycles of wetting and drying under controlled laboratory conditions. Identical samples were subjected to different surcharge pressures such as 6.25, 12.5, 25, 50, 100 and 200 kPa so as to simulate the depth in the field. The samples were dried up to equilibrium at a temperature of 40 ± 5°C, in a thermostat controlled oedometer. Wetting was done by submerging the samples under water. The movements during wetting and drying were recorded and it was found that equilibrium is reached in about five cycles. After reaching equilibrium, samples were unloaded to a seating pressure of 6.25 kPa and conventional one-dimensional consolidation testwas conducted. The experimental results showthat the yield stress of desiccated expansive soil depends on the surcharge pressure. The overconsolidation margin, which is the difference between the yield stress and the effective vertical stress, of desiccated expansive soil is almost constant of about 100 kPa. This suggest that desiccation induced yield stress is similar to overburden pressure in the geological past. © 2010 Taylor & Francis Group, London.