Rainfall induced transient pressure wave mechanisms and pore water pressure dynamics in tailings

Abstract

Tailings Storage Facilities are some of the largest engineered structures responsible for the containment of mining waste, yet some physical/hydrological processes causing slope instability are still poorly understood. Previous studies conducted on the causes of failure of TSFs indicate rainfall-induced slope instability as the main trigger. However, the generation of certain physical/hydrological processes and the behaviour of soil hydraulic properties in the vadose zone when exposed to high intensity rainfall events, have only been considered on natural hillslopes. The purpose of this study is to investigate one such process resulting from high rainfall intensities on partially saturated conditions. In particular, it is hypothesised in this work that the wetting front advance from high rainfall intensities, anticipated under the force of climate change, may cause transient air pressure waves to change pore water suction and elevate the phreatic surface, subsequently impacting on the effective stress. The mechanisms that lead to the mobilisation of pre-event water through transient air pressure waves are known as Groundwater Ridging and the Lisse Effect. In this study, it was hypothesized that these phenomena contribute significantly to slope instability.