Behaviors of rainfall infiltration and drainage characteristics of unsaturated soils under relatively high suction state

Abstract

In this study, behaviors of the volumetric water content and the soil suction due to rainfall infiltration and drainage characteristics under relatively high suction state were discussed through the macro-pores part and the matrix part separately based on the results of in-situ measurement made at the fill slope where macro-pores developed. As a result, despite the volume water content drops below the field capacity at the start of in-situ rainfall and the pore pressure is less than the corresponding values, the process of rainfall infiltration and drainage characteristics exhibited along the boundary drainage of the matrix flow at maximum field capacity corresponds to the scanning curve. In addition, even if the installation position of the measurement interval was about 0.4m in this slope, the extremely heterogeneous distributions in volumetric water content and pore pressure lead to a lack of synchronicity observed between the volumetric water content and the pore pressure when the macro-pore flow occurred. Therefore, the effect of the measurement interval should be considered when interpreting the measurement results.