Soil column infiltration tests on biomediated capillary barrier systems for mitigating rainfall-induced landslides

Rainfall-induced landslide is a common geohazard in tropical and humid regions. Capillary barrier system (CBS) is a popular and widely studied mitigating measure for rainfall-induced landslides. However, several previous studies have shown that the performance of the conventional CBS under intense rainfalls has not been particularly convincing. This paper aims to explore the feasibility and effectiveness of a newly proposed system, known as "biomediated capillary barrier system" (B-CBS) in minimizing water infiltration into soil. A one-dimensional soil column was used to investigate the infiltration characteristics of the proposed system. The results showed that the B-CBS of biomediated residual soil overlying original residual soil (Test IV) could effectively control the infiltration into soil by taking advantage of the less-permeable biomediated soil cover. The B-CBS of biomediated residual soil overlying gravelly sand (Test V) and the three-layered B-CBS of fine sand overlying gravelly sand and biomediated residual soil (Test VI) showed the best performance in terms of minimizing the water infiltration. A suction of about 5 kPa still remained in the soil column after 60 min of infiltration from the ponded water on the soil surface.