Insights Into Coal Pillar-Support Interaction Using Large-Scale Laboratory Tests and Discrete Element Modeling

ABSTRACT: Coal pillars are essential for stabilizing mine entries in underground and highwall coal mines. Despite extensive research involving in-situ tests, laboratory experiments, field monitoring, and numerical modeling, challenges such as slabbing and buckling persist, leading to injuries and fatalities. Ground support elements like rock bolts, wire mesh, and face plates are employed to address these issues. However, the design of coal pillar support is still largely based on local practices and experience without full consideration of the mechanics of pillar-support interaction. This study explores the influence of ground support on coal pillar strength, deformation behavior, and support load evolution through large-scale laboratory tests and numerical modeling. Although laboratory tests are expensive and time-consuming, they offer controlled conditions for full-scale support elements, allowing for field-scale extrapolation. To supplement these tests, discontinuum modeling tools can be applied to simulate rock micro-fracturing and large-strain behavior. Given the brittle and anisotropic nature of coal, characterized by bedding planes and cleats, this study uses a 3D Discrete Element Model (DEM) incorporating these discontinuities based on field data. The models are calibrated using large-scale laboratory datasets and then various support configurations are installed within the coal pillar model. The research aims to develop insights into coal pillar-support interaction, ultimately contributing to the development of safer and more effective ground support designs in underground coal mining operations.