Ground control is paramount in soft-rock mines due to the inherent low strength and deformability of materials like coal, salt, and potash. These environments are susceptible to various ground failures (Prairie Machine, 2025).
Roof and rib instabilities, including rock falls from discontinuities and stress-induced spalling, are common. These are often driven by adverse geological conditions and mining-induced stress changes (MSHA, 1996).
Pillar system failures are a major concern, ranging from gradual yielding and progressive failure to sudden, violent crushing or bursting, and in severe cases, catastrophic collapses like the Crandall Canyon disaster (MSHA, 2021).
Floor instability often manifests as floor heave, where weak underclays buckle upwards, or as squeezing ground, where entire openings converge due to high stress in weak rock masses (University of Kentucky Geological Survey, n.d.).
Evaporites like salt and potash are particularly prone to time-dependent deformation (creep), leading to slow closure and stress redistribution that can trigger failures. Water ingress further exacerbates instability by dissolving soluble minerals or causing swelling and strength reduction in clay-bearing strata (Liu et al., 2023a).
Effective ground control, therefore, relies on thorough geotechnical investigation, robust engineering design, and diligent monitoring to mitigate these risks and ensure worker safety (NIOSH, n.d.).
Which type of ground failure do you think poses the greatest risk in soft-rock mining? Share your thoughts!
References:
Liu, J., Yang, X., Zhang, N., Wang, E., & Li, B. (2023a). Study on the deformation and instability mechanism of swelling soft rock roadway in Kailuan mining area. Scientific Reports, 13, 21169. https://pmc.ncbi.nlm.nih.gov/articles/PMC10673829/
MSHA (Mine Safety and Health Administration). (1996). Fatal Coal Burst Accident, C-2 Mine. https://arlweb.msha.gov/fatals/1996/ftl96c34.htm
MSHA (Mine Safety and Health Administration). (2021). Pillar Collapse Risk Analysis. (https://www.msha.gov/sites/default/files/events/Pillar-Collapse-Risk-Analysis-2021-.pdf)
NIOSH (National Institute for Occupational Safety and Health). (n.d.). Ground Falls. https://www.cdc.gov/niosh/mining/topics/ground-falls.html
Prairie Machine. (2025). Hard Rock vs Soft Rock Mining: What’s the Difference? (https://prairiemachine.com/blog/20250303-RockMiningTypes)
University of Kentucky Geological Survey (UKY KGS). (n.d.). Floor Heave and “Squeeze”. (https://www.uky.edu/KGS/coal/coal-mining-geology-floor-heave.php)
