Research Status of Coal Gangue Slope Stability and Integrated Protection

Abstract

Coal gangue slopes are characterized by heterogeneity in particle size and lithology, a loose structure, water-induced softening and disintegration, and nutrient-poor ecological substrates. Their stability is jointly controlled by compaction, weathering, wet-dry cycles, slope geometry, filling or stripping sequence, rainfall infiltration, and the foundation-cover interface. This review summarizes the main advances in field investigation and testing, limit-equilibrium methods, FLAC3D, GeoStudio, PFC3D, and CFD-DEM coupling. The synthesis indicates that higher compaction and benched construction generally improve stability, whereas saturation and repeated wetting markedly reduce cohesion and friction angle; rainfall-induced failure commonly progresses through surface wetting, infiltration, local movement at the slope toe or benches, and eventual connection of deep or foundation-cover interface shear zones. Treatment has evolved from isolated retaining measures toward integrated slope reshaping, interception and drainage, structural support, substrate improvement, vegetation restoration, and monitoring. Current studies remain limited by single-project samples, insufficient long-term monitoring, limited consideration of spatial parameter variability, and incomplete coupling of hydro-mechanical-ecological processes. Future work should build standardized multiscale monitoring datasets, develop two-way coupling and probabilistic evaluation methods, and verify integrated treatment performance throughout the life cycle.