SELF-DRILLING AND SELF-ANCHORING ANCHOR BOLT CAPABLE OF BEING LENGTHENED AND SUITABLE FOR WEAK COAL, AND ANCHORING METHOD THEREOF

摘要

A self-drilling and self-anchoring anchor bolt capable of being lengthened and suitable for weak coal, and an anchoring method thereof, applied to weak coal mass supporting engineering in tunnels. An anchor bolt body comprises five parts, i.e., a simple drill bit (1), middle bolt bodies (2), connection sleeves (3), a tail bolt body (4), and a conical rubber plug (5). The anchoring method comprises: first drilling 1/4-3/4 the depth of a drill hole using a drill pipe; then, assembling the anchor bolt according to requirements for drilling, when the final section of the bolt bodies is assembled for lengthening, replacing a middle bolt body (2) with the tail bolt body (4) for lengthening, implementing the self-anchoring function by a anchoring force formed by friction between coal powder produced by self-drilling of the anchor bolt and quick shrinkage deformation of the drill hole, and then performing pretension, so that self-drilling and self-anchoring are implemented. A hole is drilled using a semi-automatic hole forming approach. The method reduces the amount of construction work, shortens the construction time of a single anchor bolt, and avoids hole failure caused by hole collapse. The anchor bolt body is a multi-section bolt body that can be lengthened, and the total length thereof can be adjusted at any time according to the needs at the jobsite; moreover, an explosive cartridge is not needed, thereby overcoming the defect of being unable to insert an explosive cartridge due to hole collapse and the defect of poor anchoring property of the explosive cartridge in a weak coal mass.