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An intuitive and user-friendly tool to assess the Coal Mine Roof Rating (CMRR) for underground coal mining geotechnical roof stability assessments.
Some advanced options are disabled for simplicity in this free version. The Pro version includes full functionality with various parameter adjustments, including groundwater, surcharge, moisture sensitivity, unit contact types, as well as detailed reporting & data export capabilities.
Add roof units to see your stratigraphic profile visualisation here.
The Coal Mine Roof Rating (CMRR) is a globally recognised system for assessing roof strata stability in underground coal mines. It consolidates various geotechnical parameters—including Uniaxial Compressive Strength (UCS), fracture spacing, and moisture sensitivity—into a single comprehensive score. This provides a clear, immediate understanding of your mine's roof stability, enabling informed decisions about roof support requirements and ensuring optimal underground safety conditions. ensuring optimal underground safety conditions.
CMRR proves invaluable throughout a mine's lifecycle, from initial feasibility studies to ongoing operations. It effectively distils complex technical data into a single, actionable figure, facilitating swift identification of vulnerable areas, monitoring of changing conditions, and comparison of different mine sections. By highlighting zones susceptible to moisture damage or fracturing, CMRR enables proactive interventions—whether through enhanced support systems or modified excavation designs—before minor issues escalate into significant problems.
Our free online CMRR calculator streamlines the assessment process considerably. Simply input essential rock core parameters to receive a precise rating reflecting your roof's overall integrity. It's particularly suitable for geologists, mining engineers, and professionals seeking clear, dependable insights without navigating overly complex procedures. Ultimately, having such a concise rating readily available helps maintain proactive management of potential roof issues, minimising operational disruptions whilst enhancing mine safety.
Molinda, G & Mark, C (1994). The Coal Mine Roof Rating (CMRR)—A Practical Rock Mass Classification for Coal Mines. US Bureau of Mines IC 9387, pp 87.
Mark, C & Molinda, GM (1996). Rating Coal Mine Roof Strength from Exploratory Drill Core. Proceedings of the 15th International Conference on Ground Control, Golden, CO, pp 415-428.
Molinda, G & Mark, C (1996). Rating the Strength of Coal Mine Roof Rocks. US Bureau of Mines IC 9387, pp 33.
Mark, C (1999). Application of the Coal Mine Roof Rating (CMRR) to Extended Cuts. Mining Engineering, 51(4), pp 52-56.
Mark, C & Molinda, GM (2005). The Coal Mine Roof Rating (CMRR)—A Decade of Experience. International Journal of Coal Geology, 64(1-2), pp 85-103.
Mark, C & Molinda, GM (2007). Development and Application of the Coal Mine Roof Rating (CMRR). In: Proceedings of the International Workshop on Rock Mass Classification in Underground Mining. Mark, C, Pakalnis, R & Tuchman, RJ, eds. Pittsburgh, PA: US Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health (NIOSH), May 2007, pp 95-109.
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