Experimental investigation on mobility and deposition characteristics of granular and poly-dispersed mine overburden dump material in inclined channels for hazard assessment

Assessing the hazard potential of granular flows in mine overburden dumps is crucial for effective disaster preparedness. A key aspect of this is understanding runout potential and depositional patterns. Previous studies on granular flows have focused on mono-dispersed or binary mixtures, which do not capture the poly-dispersity typical of mine overburden dumps. This study addresses this gap by analyzing the runout and depositional characteristics of poly-dispersed mine overburden materials in a 3-m flume. Nine mixtures with varying mass ratios (fines to total mass) and size ratios (D50 of coarse to D50 of fine particles) were tested at inclinations of 30°, 35°, and 40°. Results indicated a critical mass ratio of 0.2, beyond which runout length and area decreased. Maximum runout distances of 33, 58, and 71 cm were observed at inclinations of 30°, 35°, and 40°, respectively. Additionally, at a fixed mass ratio, an increase in size ratio caused longer runout distances. Notably, coarse particles accumulate in the trailing half of the flow at higher slopes, suggesting a recirculating pattern where they rise to the surface and settle toward the rear as energy dissipates. These findings highlight the role of poly-dispersity and particle angularity in influencing deposition behavior.