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|Identifying the properties of overlying rocks in underground mining operations is important to ensure the appropriate roof support design is used to maintain stability of the mine entries. Recently J. H. Fletcher & Co. developed a monitoring and control system for roof bolters for the underground mining industry. The system records the drilling parameters used during roof bolt drilling and the information can provide insight into the physical properties of the roof strata. The parameters include thrust, rotational speed, torque and velocity and the measurements are collected every 0.1 second during the operation. The drilling parameters were analyzed to determine the application of identifying the strength of rocks being drilled from the measurements. The data was converted into the specific energy of drilling which is a measure of the amount of energy required for removing a given unit of rock during a drilling operation. The laboratory studies completed to date indicate a fairly high correlation between the specific energy of drilling and the unconfined compressive strength of the rocks that were drilled. Additionally, the drilling parameters were shown to be effective for identifying the presence of fractures or bed separations between rock ]avers. The thrust, torque and specific energy of drilling were all good indicators for identifying the fractures or separations. Regardless of the drilling parameters used during the drilling experiments, the location of the fractures were identified, In order to determine the application of the drilling parameters for identifying rout rock properties, two series of experiments were conducted. The first series of experiments used three "manufactured" roof layers that had various rock samples embedded in concrete blocks. The rock samples included three types of sandstone, marble. and argillite. Another concrete block was poured with foam inserts to simulate large bedding separations (2 to 8-in). Two other manufactured blocks were constructed using high-strength concrete with cardboard layers embedded to simulate smaller fractures or bedding separations. The size of the cardboard layers varied from 1/8- to 1-in thick. One of the blocks had the cardboard layers embedded at an inclined angle to determine the effect of the orientation or, the drilling parameters. A series of experiments was conducted with the rotational speed and the penetration rate held constant and the thrust and torque allowed to vary. The information collected from the experiments is used to determine the application of the drilling parameter measurements for identifying rock properties, fractures and bedding separations.|
Additional chapters/articles from the SME-ICGCM book Proceedings 19th International Conference On Ground Control In Mining
|An Approach To Identifying Geological Properties From Roof B||Field Experience Of Measuring The Acoustic Energy From A Ham||Advancements In Reflective Seismic Tomography For The Locati||Longwall Geomechanics, An Australian Perspective||Moonee Colliery: Renewing The Economic Viability Of A Mine U||Successful Application Of Hydraulic Fracturing To Control Wi||Pillar Mining And Longwalling Below Massive Roof Strata: Geo||High Capacity Tensioned Cable Bolts For Tailgate Support||Single Point And Full Scale Laboratory Testing Of Timber Cho||Optimizing Secondary Roof Support With The NIOSH Support Tec||The Use Of Cribless Tailgates In Longwall Extraction||Five Stress Factors Conducive To Bumps In Utah, USA, Coal Mi||Development Of Stress Measurement Techniques In Bump-Prone C||Coal Mine Seismicity And Bumps: Historical Case Studies And||Multi-Scale Assessment Of Coal And Gas Outbursts Based On Fr||Horizontal Stress: The Root Of All Evil?||Utilizing The ?Advance And Relieve? Method To Reduce Horizon||Regional Horizontal Surface Displacements Due To Mining Bene||Prognosis And Control Of Mining Induced Surface Subsidence A||Prediction Of Subsurface Subsidence For Longwall Mining Oper||Development Of A Statistical Technique For Assessing Sandsto||Evaluation Of Surface Subsidence Potential Along A Pipeline||Roof Monitoring In Limestone Mines-Experience With The Roof||Site Characterization For Planning Underground Stone Mines||Potential Problems Related To Mining Under Or Adjacent To Fl||Mine Planning For Longwall And Pillar Retreat Panels Subject||Optimization Of District-Wide Mine Layout In Multi-Seam Mini||Application Of Bolt Design Criteria At Galatia Mine||The Utilization Of Rockbolting Technology And Monitoring Tec||Rockbolting For Highly Stressed Roadways||Evaluation Of Measurement System For Monitoring The Stabilit||Quality Management For Grouted Rockbolts||Evaluating Anchorage Mechanisms Of Fully Encapsulated Rock B||INSTáL CableOx: A New Tensionable & Corrosion Resistant Cabl||Rock Reinforcement Longevity||Progress In The Development Of A Roof Bolt Design Methodolog||Case Studies Of Progressive Pillar Failure In Two Mines Usin||Jointing Effects On Pillar Strength||Impact Of Vertical Stress On Roadway Conditions At Dartbrook||Stepwise Support Technology For Extremely Soft Rock Roadway||Mobile Roof Supports For Pillar Retreat Mining||Three-Dimensional Simulations Of The Roof Behavior In Coal R||Roof Behavior In South African Coal Room And Pillar Panels||Extended Cut Out Distances In Continuous Miner Sections In S||Roof Control Analysis In North River Mine||Analysis Of The Seam Inclination Effect On Roof Stability||The Application Of Rock Mass Classification Principles To Co||Mining Geotechnical Benchmarking||Using The Point Load Test To Determine The Uniaxial Compress||The Influence Of Water Content On Strength Characteristic Of||Polymer Membrane Liners In Underground Coal Mines - Ground C||Applications Of Cement Grouting Method For Controlling Weak||Analysis Of Safety Aspects And Mining Practices For Effectiv|