TENSIONING DEVICE FOR THE TIE LINK OF AN ANCHOR, ESPECIALLY A ROCK ANCHOR

摘要

An anchoring apparatus for insertion into a borehole in a rock stratum for supporting the rock surface or wall, such as in a rock tunnel or rock excavation, includes a tension member in the form of an axially elongated steel rod with force transmission ribs on its outer surface and an anchoring element, such an anchoring nut, engageable with the rod. The anchoring element has an inside surface with inwardly extending projections and the adjacent flanks on the projections form grooves within which the force transmission ribs engage. The anchoring element is formed of a higher strength material than the rod. When a predetermined axially extending tension force acting on the rod is exceeded, relative movement takes place between the anchoring element and the rod. The flanks on the projections on the anchoring element in contact with the ribs on the rod shear off a portion of the ribs contacted. Accordingly, while the predetermined force is exceeded, the shearing action proceeds and affords a sliding anchoring effect between the rod and the anchoring element.