Rock anchor

摘要

A rock anchor is known which consists of a smooth, centre length section and two end sections profiled on the periphery. The end sections are secured in the bore hole by adhesive and serve to transmit force. The centre length section is to be changeable in length through extension in the event of rock convergence. However, the end sections, as rule formed by rolled threads, contract to a considerably degree, especially in the case of highly extensible steels, so that the adhesion with the adhesive is lost and the anchors can slide out of the rock. The invention provides a rock anchor 1 which has a constant cross-sectional area over its entire length. This is achieved by flats 12 of the end sections 7, 9 with adjoining helix. The large pitch of the helices 7, 9 guarantees satisfactory positive-locking with the adhesive 14 so that the clasping in the bore hole 5 is maintained when there is considerable rock convergence and the rock anchor 1 becomes longer as a result. <IMAGE>