Deformation and failure of a high-steep slope induced by multi-layer coal mining

Abstract

During underground mining, accurate revelation on the deformation and failure mechanisms of a high-steep slope under multi-layer mining conditions facilitates the prevention and control of geological disasters in mines. Numerical simulation based on discrete element theory can be used to explore the characteristics and mechanism of action of deformation and failure of a slope under complex geological and multi-layer mining conditions. By utilising PFC2D (particle flow code) software, the deformation and failure characteristics of a high-steep slope in Faer Coal Mine in Guizhou Province, China were investigated. Additionally, the mechanism of influence of different numbers of mining layers on the deformation and failure of the high and steep slope was elucidated. The result showed that after the goaf passed by the slope toe, multi-layer mining aggravated the subsidence and deformation of the slope toe: the slope toppled forward as it sank. The toppling of the slope changed the slope structures: the strata in the front of the slope were transformed from anti-dip to down-dip features. Extruded by collapsed–toppled rock mass, the slope toe and the rock mass located in the lower part of the slope toe generally exhibited a locking effect on the slope. Multi-layer mining degraded the overall stability of the slope, in that the total displacement of the slope was much greater than the total mining thickness of the coal seams. Based on the aforementioned research, ideas for preventing and controlling geological disasters during mining operations under a high-steep slope were proposed.