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Mining Publication: Development and Application of the Coal Mine Roof Rating (CMRR)

NOTE: This page is archived for historical purposes and is no longer being maintained or updated.

Original creation date: May 2007

Image of publication Development and Application of the Coal Mine Roof Rating (CMRR)

The Coal Mine Roof Rating (CMRR) was developed 10 years ago to fill the gap between geologic characterization and engineering design. It combines many years of geologic studies in underground coal mines with worldwide experience with rock mass classification systems. Like other classification systems, the CMRR begins with the premise that the structural competence of mine roof rock is determined mainly by the discontinuities that weaken the rock fabric. However, the CMRR is specifically designed for bedded coal measure rock. Since its introduction, the CMRR has been incorporated into many aspects of mine planning, including longwall pillar design, roof support selection, feasibility studies, extended-cut evaluation, and others. It has also become truly international, with involvement in mine designs and funded research projects in South Africa, Canada, and Australia. This paper discusses the sources used in developing the CMRR, describes the CMRR data collection and calculation procedures, and briefly presents a number of practical mining applications in which the CMRR has played a prominent role.

Authors: C Mark, GM Molinda

Conference Paper - May 2007

NIOSHTIC2 Number: 20032090

Proceedings of the International Workshop on Rock Mass Classification in Underground Mining. Mark C; Pakalnis R; Tuchman RJ, eds., Pittsburgh, PA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, 2007 May; :95-109