Centrifuge modelling of root-reinforced soil slope subjected to rainfall infiltration

Abstract

Slope instability induced by heavy rainfall is a serious geotechnical hazard all over the world. The characteristics of water flow, pore water pressure changes and shear strength of the soil are the main factors involved in slope failure mechanisms. This paper describes soil slope failure induced by rainfall using a rainfall simulator in a geotechnical centrifuge. To study a soil-bioengineering slope stabilisation technique in a small centrifuge, a sloping rooted surface layer was simulated by mixing polyester fibres into the soil. The test results indicate that a rise in the groundwater table due to rainwater infiltration was responsible for slope failure and failure near the toe propagated upslope in a bare soil slope. On the other hand, a slope whose surface was reinforced with roots exhibited small deformation without failure under heavy rainfall (intensity of 20 mm/h) for a duration of 15 h at prototype scale. The test results also reveal that roots can help to reduce the infiltration of rainwater into the ground, delay a rise in groundwater table and increase the shear strength of the soil.