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CMRR (Coal Mine Roof Rating) is software for estimating the relative inherent strength of coal mine roof.
The Coal Mine Roof Rating is a roof classification system that was first introduced to the mining community in 1994. It filled a longstanding need to quantify geologic description of coal measure rocks into an engineering value which could be used for mining design purposes. Rocks which form the roof of coal mines can vary widely and quickly in composition, extent, and defects. This results in an equally broad range of rock properties which can substantially affect the ability of the rock mass to form a stable mine roof. The CMRR was designed to evaluate the properties of the coal mine roof rock mass which contribute to its´ weakness and convert them into a relative strength rating from 0-100. These properties include the cohesion and frequency of discontinuities like bedding, slips, shears, and joints, UCS, and moisture sensitivity. With simple laboratory and field tests and observation, the CMRR can be calculated by technical and operating personnel with a minimum of training.
Originally designed to be used with underground exposures, the CMRR can also be calculated from core. The CMRR has found a wide range of applications. These include: integration into ALPS and ALTS, the chain pillar design program for longwall gateroads in both the U.S. and Australia; in the assessment of the suitability of extended cuts; roof bolt selection; roof fall evaluations; input for numerical models; and in tailgate support guidelines.
Related Products:
- Ground Control Software Toolbar - Analysis Software
Related Documents:
- New Developments with the Coal Mine Roof Rating (PDF, 1358 KB, 2002)
- Technology News 505 - NIOSH Releases New Coal Mine Roof Rating Software (PDF, 278 KB, 2003-04)
- Technology News 517 - New Updates for NIOSH Coal Mine Ground Control Software (PDF, 632 KB, 2006-04)