Experimental study of the failure mode and mechanism of loess fill slopes induced by rainfall

Loess fill slopes are vulnerable to heavy rainfall because of water sensitivity and collapsibility of loess. Studies on the failure mode and mechanism of loess fill slopes are limited and incomplete. In this study, a laboratory flume test is carried out to simulate the failure mode of loess fill slope by monitoring and analyzing its soil hydrological and mechanical parameters including volumetric water content, pore water pressure and horizontal earth pressure. The results show that under continuous rainfall, loess fill slope fails in a backward retrogressive failure mode including gully erosion, partial failure, slope toe failure, central slope failure and top slope failure stages. The failure mechanism of each failure stage has been explained based on the variation of slope hydrological and mechanical conditions with the rainwater infiltration. The evolution processes of the fissures and its effects on the slope failure have been investigated. It is revealed that fissures play an important role in failing the slope by generating preferential flow. Finally, some engineering measures are recommended for the prevention of loess fill slope failure.

Automated summary

Loess fill slopes are susceptible to heavy rainfall due to their water sensitivity and collapsibility. The failure mode of loess fill slopes under continuous rainfall is characterized by gully erosion, slope toe failure, central slope failure, and top slope failure. The study reveals that fissures play a crucial role in slope failure by generating preferential flow.