Multiple Point Anchor (MPA), Self-Drilling, Hollow Core Yielding Bolt with Injectable J-Lok P Resin System for High-Stress and Squeezing Ground Conditions

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.