Abstract
The mechanism of sediment disaster induced by heavy rain should be elucidated and then the prediction method is applied to prevent the sediment disaster. It is qualitatively known that the sediment disaster induced by heavy rain is caused by the change in the mechanical properties of unsaturated soil, for example the decrease in suction. The soil-water characteristic curve (SWCC) which has hysteresis is a key relation to simulate the seepage of rain water into unsaturated soil. In this paper a numerical & mechanical model is proposed to express the main drying curve (MDC), main wetting curve (MWC), drying scanning curve (DSC) and wetting scanning curve (WSC), where the maximum and minimum void ratios are used to determine the residual and quasi-saturated degrees of saturation, Srr and Srs.
