Erosion Failure of Slope in a Dump with Ground Fissure under Heavy Rain

Abstract

The dump, with the compact rock platform and high and steep loose slope that is formed during coal mining, is the most serious area of soil erosion in a surface coal mine. Ground fissures are a typical geological hazard in coal mining areas. However, the effect of ground fissures on soil erosion remains unclear. Rainfall experiments were conducted to determine the varying characteristics of wetting front, runoff and sediment production, and soil denudation rate, as well as the effects of ground fissures on these factors in a platform-slope system of a dump. Ground fissures could significantly enhance wetting front and soil erosion. Rill erosion was formed as the rainfall and runoff flushed the soil, which eventually developed into erosion gullies. Erosion failure modes with platform-slope systems in the dump could be divided into the surface erosion stage, fissure deformation stage, rill erosion stage, fissure collapse-rapid increase stage, and stable stage. Runoff power and flow shear stress had the greater influence on soil denudation rate, which indicated that erosion energy of concentrated flow had important influence on soil erosion. Moreover, shallow mudflow induced by rainfall was one of the forms of soil slope instability; it occurred in a short time with great soil erosion. Soil erosion in the dump with ground fissures was mainly shallow mudflow and rill erosion, resulting from the combined effect of hydraulic erosion and gravity erosion.