Prediction and Application of Equilibrium Water Content of Expansive Soil Subgrade

In order to investigate water equilibrium of expansive soil subgrade, equilibrium water content of recompacted, expansive soil under different stress conditions in wide suction range is measured, and the key parameter for numerical analysis is obtained. A two-dimensional subgrade-atmosphere interaction model is developed and used to numerically simulate variation of water content of a covered, expansive soil subgrade in 10 years. Compaction control criterion for expansive soil subgrade is proposed considering the equilibrium water content. The results show that equilibrium water content is stress-dependent in suction of 0-3 MPa. Water content of subgrade increases slowly in 8 years and reaches equilibrium state finally. The optimum water content of wet compaction is close to equilibrium water content and natural water content of expansive soil in moist and hot climate. Compaction of expansive soil subgrade should be controlled in light of wet compaction criterion.