Moisture migration tests on unsaturated expansive clays in Hefei, China

Expansive clay in semiarid area behaves features of typical unsaturated soil, which is sensitive to climate and moisture, and appears multi-fissures, deterioration of mechanical performances with the change of moisture. Consequently, to ensure the rational design of foundation treatment, and safe operation, research on moisture migration of expansive clays is of great significance. Herein, test models of mixed water migration and vaporous water migration were presented to find out the mechanism. Series of tests, in which the moisture content in left soil column was the same as 24%, and in right soil column was 0%, 6%, 12% and 18% respectively, were conducted under constant temperature. It is concluded that moisture content changed with the increase of migration time in both migration models. And the migration behaves nonlinearly when the initial water content increases up to 6% for mixed water migration model and 12% for vaporous water migration model. But the migration characteristics of mixed water and vaporous water were different. In the initial 30 days the change of moisture water was larger in mixed migration model, however within 60 to 90 days, it was larger in vaporous water migration model. The research results have been applied to guide relevant engineering practice.