Erosion, runoff and deformation of overburden stockpiles subjected to simulated rainfall

Overburden stockpiles from production and construction projects often fail to achieve natural stability within the short time period, potentially leading to catastrophic failures such as landslides and debris flows. To investigate the erosion and deformation characteristics of overburden stockpiles and their interrelationships, we conducted a series of laboratory experiments under simulated rainfall of varying intensities. Results demonstrated that increased rainfall intensity led to concurrent increases in sediment yield, runoff production, runoff rate and the maximum rill width, length and depth. The total subsidence depth increased with an increase in rainfall intensity. When examining the effects of gravel content (10%, 20%, 30% and 40%), both sediment yield and runoff yield displayed an initial increase followed by a decrease. The temporal evolution of runoff rate manifested in three distinct phases: rapid acceleration, gradual increase and stabilization. The rate of subsidence depth development initially accelerated but subsequently decelerated with successive rainfall events. At high rainfall intensity, total subsidence depth increased proportionally with gravel content. The creep degree of overburden stockpiles intensified with increased rainfall intensity and gravel content. Furthermore, the relationship between deformation rate and both sediment yield and runoff exhibited sigmoid curves, with an initial acceleration followed by deceleration. The time to instability decreased with increasing rainfall intensity while showing an initial increase followed by a decrease pattern at high rainfall intensities with increasing gravel content. Our findings provide guidance for mitigating soil loss and preventing hazardous events associated with overburden stockpiles.