Retrogressive Failure of Reservoir Rim Sandy Slopes Induced by Steady-State Seepage Condition

Reservoir rim slopes often experience seepage-induced slope instability during rainfall season. The predominant phenomenon observed during monsoons is the establishment of continuous seeping conditions, either steady or unsteady in nature. The infiltrated rainwater seeping toward the drainage basin may induce instability in the slope. This paper presents results from an experimental study conducted to investigate the failure mechanism of a cohesionless soil slope under a steady-state seepage condition. Retrogressive multiple rotational slide type of slope failure occurred during experimentation. It was observed that the failure didn't occur in one go; instead, it was progressive with time. In usual practice by engineers, while performing numerical simulations for a field problem, the focus is on the formation of failure surface and deformations observed. But, the limitation with such studies is that the movement of the slope surface over a period of time cannot be investigated. It is, therefore, suggested that emphasis should be laid upon the time-dependent analysis as well.