Effect of clay content on well-graded sands due to infiltration

This paper describes various experimental studies and numerical analyses to simulate the rainfall-induced slope failures caused by infiltration due to prolonged rainfall. The emphasis was on quantifying the effect of fine-grained contents which influence the infiltration rate of the wetting front of initially unsaturated slopes during rainfall. Suction tests using a tensiometer were performed for the wetting front suction of five mixture samples with varying fine-grained contents. Subsequently, numerical analyses for the stability of unsaturated infinite slopes were carried out for different relative densities and mixture portions based on the soil water characteristic curves obtained by a pressure plate. In the stability analyses, the interface between fully saturated- and partially saturated-zones was chosen as a relatively failure surface that develops parallel to the original slope. It is shown that the fines are highly influential on the wetting front suction of unsaturated soil slopes. Based on the results, it is found that fines affect wetting front suction up to 15% fines content, and also the wetting front suction beyond 15% fines content does not considerably influence the stability of unsaturated slopes.