Anchoring effect guarantee method and experiment for the bottom reaming area of borehole in weak surrounding rock of coal mine roadway

As a technical measure to enhance the support effect of bolts (cable bolts) on weak surrounding rock roadway in coal mine, the borehole reaming has played an important role in improving the quality and safety of active support for weak surrounding rock of coal mine roadway. However, the reaming construction also significantly increases the size of the boreholes at the reaming location. This leads to problems such as the curing and filling effect of the resin in the borehole area reamed is not ideal when the construction is carried out in accordance with the conventional resin anchoring construction method of the bolt, which is obviously not conducive to the full play of the anchoring performance of the borehole reaming. In order to clarify the anchoring problem and its influence in the reaming area of the borehole and find an effective solution to ensure the anchoring performance of the bolts (cable bolts) under the reaming condition of the borehole, a systematic study was carried out by combining numerical simulation and laboratory experiments. The results show that the bending (curving) of the resin cartridges into the reaming area during construction process, which makes it impossible for the cable bolt to effectively mix and break resin cartridges, and the increase of the volume of the borehole at the reaming position makes the resin unable to fill effectively, they are the main reasons for the anchoring problems in the reaming area. The simulation results of cable bolt pull-out show that the anchoring defects in the reaming area have a great impact on the anchoring performance of the cable bolt and the failure mode of the anchoring system. In order to improve the anchoring effect of the reaming area, this paper proposes a method to guarantee the anchoring effect of the reaming area at the borehole bottom, and the effectiveness of the method is verified by experiments. The experimental results show that this method can effectively ensure the anchoring effect of the reaming area at the bottom of the borehole in weak surrounding rock, and enhance anchoring performance of the cable bolt. This study effectively solves the anchoring problem in the reaming area of the borehole, which is helpful to give full play to the high strength support ability of the cable bolt under the condition of weak surrounding rock in the coal mine, and provides a technical way to ensure the support effect of the cable bolt in weak surrounding rock.