Coal Rib Stability Based on the Strength Reduction of the Coal Mass Model

Rib falls are a major hazard in underground coal mines. Currently, rib control in coal mines in the United States is defined based on a trial-and-error approach. To eliminate fatalities caused by rib falls, researchers at the National Institute for Occupational Safety and Health (NIOSH) are conducting a research project for developing an engineering-based rib design methodology. Numerical modeling of the fracture mechanism of coal ribs and the assessment of their stability are the cornerstones in this methodology. NIOSH recently developed a coal mass model to realistically simulate the deformation and loading behaviors of coal ribs. The reduction in the strength of the coal specimen as its size increases is considered by introducing a scale parameter called Coal Mass Scale (CMS). In this paper, a procedure to calculate the factor of safety (FOS) of coal ribs was proposed by using the strength reduction method (SRM). The key function of this procedure is that the strength of the coal material is reduced by increasing the CMS of the coal mass model. The proposed method was verified using a case study of surveyed coal rib in underground coal mine.