Optimizing support performances of bolt reaming and anchoring in a coal drift

In current practice of bolt reaming and anchoring of roadways in soft coal and rock mass, resin cartridges bend easily under the strong pushing and stirring of bolts, and the resin accumulates in the bolt-reamed area and does not participate in the stirring. As a result, bolts encounter high drilling resistance and cannot reach the bottom of drillholes. The effective anchorage length is far less than the actual anchorage length. Bolts are not centered, and the shear is misaligned at the joint surface in the reaming area, which leads to cracking of the whole anchoring solid and large shear deformation of bolts. This study systematically analyzes the characteristics of roadway bolt reaming and anchoring. The influences of resin stirring force, bolt pull-out force, and reaming–anchoring solid strength on reaming–anchoring performance were analyzed theoretically. The main purpose is to develop a device that enhances reaming and anchoring. The mechanism through which the device strengthens the reaming–anchoring solid was analyzed theoretically. Numerical simulation and experiments were carried out to verify the improved performance of the small-pore reaming and anchoring using the proposed technology. The results showed that the stirring migration rate of the resin cartridge is greatly improved by adding the device to bolts. The reaction rate of the anchoring mixture, stirring pressure, pull-out force of the reaming and anchoring system, bolt concentricity, and shear and compressive strengths of the anchoring solid are also enhanced in the reaming area. This ensures that the resin cartridge in the reaming area is completely stirred, which greatly improves the shear resistance of the reaming–anchoring solid. Meanwhile, the drilling performance, torsional force, and stirring efficiency of bolts are maximized and prevail over those of conventional bolts.