Laboratory experimental study of soil-water characteristic curves of unsaturated soils of Zhengzhou-Kaifeng underpass project

Based on osmotic method and vapor phase technique, the soil-water characteristic curves of unsaturated soils-the sandy powder soil and the silty clay which produced by dewatering construction of Zhongzhou-Kaifeng underpass project were studied. Results show that the air-enter values for the sandy powder soil and the silty clay are about 2 kPa and 250 kPa; the residual saturation degree values are about 15 MPa and 28 MPa and the desorption process of both unsaturated soils shows clearly in step-phase. The step-phase study of characteristic curves of unsaturated soils has very important meaningful for dewatering construction and the excavation face reinforcement of Zhengzhou-Kaifeng project.