DEM-FDM investigation of bedding plane properties' impact on laminated roof stability

Laminated roofs are susceptible to cutter roof failure caused by excavation disturbances. To assess the impact of bedding plane properties on their stability under mining stress, a panel-scale numerical model was created using a combination of the discrete element method (DEM) and finite differential method (FDM). The laminated roof was modeled with a bonded particle model (BPM) integrated with a discrete fracture network (DFN) to closely examine fracture behavior, while the surrounding rock was treated as a continuum material. The model was validated through a uniaxial compressive test on Berea sandstone. This validated model was then used to study how varying bedding plane strength and the cohesion-to-tensile strength ratio affect roof deformation, fracturing, and failure during entry development and panel extraction. The findings indicated that entry development caused more roof deformation than panel extraction. Increasing bedding plane strength enhanced the overall stability of the roof, reducing damage to both bedding planes and individual layers. Roof deformation was more sensitive to changes in bedding strength, especially when the bedding was weak. Reducing bedding plane strength led to more shear-tensile cracks and overall damage, particularly in weaker structures. This coupling method was proved to enable the simulation of large-scale panel extraction conditions at an efficient computational cost.