Research on the influence of bottom expanding and filling on bolt sliding instability and supporting effect

Abstract

Aiming at the problems of soft coal roadway, such as low hardness, fracture development, poor bonding ability between anchoring agent and surrounding rock of borehole, weak shear resistance, which easily lead to resin bolt sliding instability in coal roadway. To effectively support soft coal roadway, the method of bottom expanding and filling is adopted. This method expands the hole at the bottom of the borehole and replaces the soft coal with high-strength material to achieve the same position modification of the soft coal body at the bottom of the borehole and improve the anchoring performance of bolt support. Through laboratory tests and numerical simulations, the sliding instability of the bottom reamed bolt is evaluated. the results show that, with the increase of the reaming times, the anchoring force changes in direct proportion to the reaming times, except single of the reaming times, the anchoring force increases fast under quintuple of the reaming times, and increases slowly over quintuple of the reaming times, so it is considered that quintuple reaming is the most appropriate.