Experimental Study of an Orientation and Resin-Lifting Device for Improving the Performance of Resin-Anchored Roof Bolts

During roof bolting in underground coal mines, the effect of gravity on the resin for anchoring the bolts, resin mixing methods, and borehole wall collapse can easily lead to resin outflow, nonuniformity of the resin, and poor bolt concentricity. In this study we developed an orientation and lifting device (OLD) for resin-anchored rock bolts. Theoretical analysis and numerical model simulations were used to analyze the working principles of the device and to optimize its important features. After manufacturing prototype devices using a 3D printer, the devices were tested by installing roof bolts into both steel tubes and a simulated mine roof in the laboratory. Push tests, pull tests, and ultrasonic tests were conducted on the bolts to measure the performance of the device. The results indicate that the device mixes resin from the resin cartridges better and has a better lifting effect on the resin than standard bolt ribs. The device can prevent the resin from flowing downward, promote uniform resin mixing and density, and improve bolt concentricity because of the device’s orientation constraint and spiral lifting capabilities. The device can raise the load bearing capacity and stiffness of the roof bolts, contribute to roadway deformation control, and enhance the energy dissipation capacity of the bolting system when subjected to static and (or) dynamic loads. Both the theoretical analysis and the laboratory experiments demonstrate that the OLD can improve the quality of the anchorage, thus enhancing mine safety. This research provides a new method for improving the quality of roadway roof bolting.