Resin reinforced expansion anchor and method of installation

Abstract

A mine roof bolt and expansion anchor are provided with means preventing relative rotation of the two in a direction tending to withdraw the bolt from the tapered nut of the anchor while allowing relative rotation in the opposite direction, whereby the bolt may be rotationally advanced into the nut as the anchor remains rotationally stationary to effect expansion of the anchor shell within a drill hole. A conventional, two-compartment resin cartridge is inserted into the drill hole ahead of the end of the bolt carrying the anchor. The cartridge is ruptured and the contents thereof mixed by advance of the bolt and anchor while rotating in the direction preventing relative rotation. Immediately thereafter the bolt is rotated in the opposite direction, thereby expanding the anchor and firmly securing it in the hole. The bolt may then be immediately loaded without regard to the setting time of the resin. Three embodiments are disclosed of the means providing the aforementioned relative rotational action. In one embodiment stop means are associated with the tapered nut for engagement by a pin extending from the threaded end of the bolt only when the latter is rotated in the direction tending to withdraw it from the nut. In a second, the stop means are associated with the base of the expansion shell and are engaged by radially extending ears on the bolt. In the third embodiment, the expansion shell is conventional in all respects and a separate collar member is carried upon the bolt shaft for engaging portions of the shell and providing the desired rotational relationships of bolt and anchor.