Self-drilling hollow core rock bolts anchored with cement grouts have been common practice in underground hard rock mines for high-stress and squeezing ground conditions. While this system has been used for many years, it results in a stiff support system that is unable to yield with the squeezing ground and takes hours of curing to reach full strength. Noticing a void in this ground support technique, Jennmar Corporation, Inc. and its subsidiary Keystone Mining Services, LLC (KMS) developed and fine-tuned the Multiple Point Anchor (MPA) hollow core yielding bolt with the injectable J-LokP resin system. The MPA is a self-drilling hollow core rock bolt designed to yield statically up to 20% before bolt failure. The MPA can also yield dynamically in high stress zone where sudden rock bursts may occur. The injectable J-LokP resin system consists of a limestone filled two-component pumpable polyester resin, J-LokP, and a specialized J-LokP pump. When used with the MPA, J-LokP is injected into the bolt through the use of a grout swivel mounted on the drill head. This allows the miner to install and anchor the bolt remotely reducing his exposure to hazards. Full anchorage of the MPA installed with J-LokP is typically obtained in less than 5 minutes. With demonstrated improvements to the safety of the miners and reduced cycle times, these products have been greatly welcomed by hard rock mines in the United States and Canada.
Multiple Point Anchor (MPA), Self-Drilling, Hollow Core Yielding Bolt with Injectable J-Lok P Resin System for High-Stress and Squeezing Ground Conditions
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Faulkner, Dakota D., Stankus, John C., Ma, Kevin J., and Lumin Ma. "Multiple Point Anchor (MPA), Self-Drilling, Hollow Core Yielding Bolt with Injectable J-Lok P Resin System for High-Stress and Squeezing Ground Conditions." Paper presented at the 51st U.S. Rock Mechanics/Geomechanics Symposium, San Francisco, California, USA, June 2017.
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