| 摘要 |
An apparatus and method for anchoring a bolt in a bore hole in a rock formation is disclosed. A tensioning assembly, which comprises a tensioning plug and expandable sheath, is threadedly engaged to the end of an elongated bolt. A ring is securely affixed to the inner wall of the plug at a predetermined point adjacent the plug's threaded portion. The end of the bolt abuts the ring upon assembly, thereby causing the bolt and the tensioning assembly to rotate together upon application of a torque to the bolt. This rotational movement effects mixing of bonding material which is placed in the bore hole ahead of the tensioning assembly. As the mixed bonding material begins to harden, rotation of the tensioning assembly is resisted. Upon application to the bolt of a torque in excess of a predetermined torque, the bolt will deform the ring located in the plug by cutting threads therein, thereby causing relative rotation of the bolt, the plug is non-rotatably drawn axially along the bolt so as to expand the sheath extensions, thereby placing them in contact with the bore hole walls. The resin mixture then bonds the entire assembly to the rock formation, thereby resisting downward movement of the sheath and allowing the bolt to be tensioned upon further rotation.
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