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|Under contract to the Bureau of Mines, a roofbolting machine has been developed which will: control torque on the bolthead to within 4 percent of a set point, control thrust to a low level (150 lbf), and implement a tightening method to minimize variability due to bolt tension decay of a group of bolts caused by differing anchor creep rates. This bolter was used to determine bolthead and thread friction factors, and to determine the effect of adding a hardened washer to the bolt assembly on the uniformity of bolt tension in the laboratory and field. Recommendations for torquing speed, bolt lubrication, use of hardened washers, and thrust level on the bolthead are made. The relationship of this system to Improved roof control is discussed, along with additional work that remains to be performed. Patent Notice Patents are pending which protect the hardware and methods of controlling tension decay as discussed in this paper.|
Additional chapters/articles from the SME-ICGCM book Proceedings Of The 1st Annual Conference On Ground Control In Mining
|Stress And Stability In Coal Ribsides And Pillars||Improved Design Of Coal Pillars For U.S. Mining Conditions||Review Of Pillar Design Equations Including The Effects Of C||Abutment Pillar "Notching" Improves Abutment Tunnel Roof Con||The Influence Of Certain Geologic And Geotechnical Factors O||Considerations Of Gas Outbursts In Using Dome Salt Mines For||An Overview Of Bureau Of Mines Ground Control Research||Stability Behaviour Of Coal Mining Tunnels With Different Su||Strata Disturbance Prediction For Mining Beneath Surface Wat||Monitoring For The Evaluation Of The Stability Of Undergroun||Controlled Thrust And Torque Placement Of Mechanical Anchor||Roklok Polyurethane Binder: A Chemical Injection System For||Resupporting High Roof Falls||A New Combination Friction-Suspension Support System Scott||Inorganic Cement Grouted Bolt System||Development Of A Resin Point Anchor||An Engineering Analysis Of "Squeeze" Failure Of Pillars In T||Ground Control In Multiple Seam Mining||Applications Of Reflection Seismics To Mapping Coal Seam Str||The Use Of Geologic Modeling In The Prediction Of Adverse Ro||Design Of Shield Supports For The U.S. Coal Mining Industry||Longwall Mining Of Thin Seams||Support Selection For The Multi-Lift Mining Method||Design And Operation Of Powered And Entry Supports||Evaluation Of Existing Predictive Methods For Mine Subsidenc||A Study Of Longwall Subsidence In The Appalachian Coal Regio||Subsidence Studies In Thick And Steep Coal Seam Mining|