Rating Coal Mine Roof Strength From Exploratory Drill Core

Mark, C.
Organization: International Conference on Ground Control in Mining
Pages: 14
Publication Date: Jan 1, 1996
Characterizing coal mine roof rock is extremely important for hazard assessment, reinforcement, and entry design. The Coal Mine Roof Rating (CMRR) is an innovative rock mass classification that has found acceptance in the coal mining industry. A disadvantage of the original CMRR is that it cannot be determined in advance of mining, because it requires underground observations. An entirely new set of procedures have now been developed to determine the CMRR from exploratory drill core, as described in this paper. The new procedures employ Point Load Tests (PLT) to determine strength parameters that account for approximately 60% of the rating. Both diametral (parallel to bedding) and axial (perpendicular to bedding) PLT are conducted. The diametral tests allow estimates of bedding plane cohesion and rock anisotropy, both of which are critical to estimating susceptibility to horizontal stress. Traditional core logging procedures are used to determine discontinuity spacing and roughness. To ensure compatibility with the original CMRR, the new rating scales were verified by comparing drill core results with nearby underground exposures. To assist mine planners in using the new CMRR procedures, a large database of strength ratings of roof rocks was assembled through extensive point load testing and logging. Over 2000 point load tests (both axial and diametral) have been made on 30 common coal measure rock types from mines representing most U.S. coalfields. This database has been merged with the popular core rating system of J.C. Ferm into a field guide for geologists and engineers. By using the pictorial classification system of Ferm to identify the rock, typical CMRR can be compared with values calculated using the new CMRR procedures.
Full Article Download:
(3649 kb)


Additional chapters/articles from the SME-ICGCM book Proceedings 15th International Conference On Ground Control In Mining

Practical Aspects Of Mobile Roof Support Usage
Chemical Consolidation For Roadway Surrounding Rock - It&apo
FortracĀ® Geogrids For Mine Roof Control
Ground Pressure Control With Use Of Freezing Rocks On The Or
Effect Of Specimen Size On Compressive Strength Of Coal
The Uniaxial Compressive Strength Of Coal: Should It Be Used
Three-Seam Interaction: A Case Study
Computer Modeling Of Rock Mass Geomechanic State In Longwall
The Influence Of Massive Sandstones In The Main Roof On Long
New Laminated Displacement-Discontinuity Program: Fundamenta
Load Determination For Long Cable Bolt Support Using Compute
Subsidence Misconceptions And Myths
Interaction Subsidence In The Sydney Coalfield, Nova Scotia
Identification Of Factors Affecting Horizontal Displacement
Subsidence Control Over Abandoned Mines
Monitoring Subsidence Over Submarine Coal Mines In The Sydne
High Horizontal Stress Effects On Longwall Gate Entry Stabil
Analysis Of Entry Roof Failure And Falls At Springvale Colli
The Effect Of Gas Pressure On Coal Strength
Applications Of Probabilistic Analysis In Mine Ground Contro
Regularities Of Rock Pressure Manifestations In Longwalls In
Design Of Multi-Level Thick Seam Extractions Under Major Aqu
State-Of-The-Art Room-And-Pillar Retreat Mining In The Kitta
Highwall Control At Homestake's Open Cut Mine
Design And Hazard Assessment Of Mine Ore Passes
Geomechanical Support Of Adaptive Mining Technology
Direct Laboratory Tensile Testing Of Select Yielding Rock Bo
Managing A New Technology - An Update Of The UK Rockbolting
Innovative Secondary Support Technologies For Western Mines
Innovation In Control Of Geomechanical State Of Undermined R
Application Of Tomographic Imaging To Stability Assessment
Using Ground Penetrating Radar For Roof Hazard Detection In
Classification Of Large Seismic Events At The Lucky Friday M
Rating Coal Mine Roof Strength From Exploratory Drill Core
Rapid Assessment Of Gateroad Roof Stability By Simple Monito
Geomechanic Monitoring And Distributed Information Systems
Monitoring Roof Beam Lateral Displacement At The Waste Isola
Laboratory Pull Tests Of Resin-Grouted Cable Bolts
Optimizing Secondary Tailgate Support Selection
Performance Evaluation Of A Cable Bolted Yield-Abutment Gate
High Horizontal Movements In Longwall Gate Roads Controlled
Shear Behavior Of Cable Bolt Supports In Horizontal, Bedded
An Evaluation Of Strata Behavior And Tailgate Support Perfor
Two Case Studies Of The Performance Of Rib Supports
Harworth Colliery: Rockbolted Support In Weak Roof At Depth
Problems And Prospects Of Roof Bolting Development At Cuzbas
Design Methods To Control Violent Pillar Failures In Room-An
Design Of Longwall Extractions Under Flooded Abandoned Worki
Effect Of Water On Stability Of Mine Roadways
Weightings And Water Inflows During Longwall Working
Underground Movement Of Rock Mass And Stress Distribution Du
Applications Of New Technologies To The Technical Design And
In-Seam Seismic Tomography Mapping Application To Coal Minin
Application Of Seismic Tomography In Underground Mining
Seismic Tomography For Longwall Stress Analysis
Geostatistical Methods For Hazard Assessment And Site Charac
Estimation Of Long-Term Stability Of Mine Pillars In Undergr
Geotechnical Factors Influencing A Time-Dependent Deformatio
Application Of Computer Programs For Rock Pressure Control
Analysis Of Multiple-Seam Interaction In A Bump-Prone Wester
Optimised Layout And Roadway Support Planning With Integrate
Automated Monitoring Of Rock Slopes And Waste Dumps
The Investigation Of The Rock Mass Stressed-Deformed State U