METHOD OF AND ARRANGEMENT FOR SETTING ANCHORS IN LOOSE ROCK RANGING FROM COHESION-POOR TO NON-COHESION ROCK

摘要

Installing rock anchors in non-cohesive rock, with regard to both the stability of the borehole wall and adequate anchorage in the rock, poses problems which can be solved - if at all - by a time-consuming and costly method in which first of all a cased bore is produced, this bore is pressure-grouted with cement mortar while removing the pipe at the same time, the hardened cement mortar is rebored for the purpose of installing an anchor and the latter is then fixed by cement mortar in the bore then produced. In the method according to the invention, an injection-boring anchor known per se is used which is provided with discharge openings merely at its front area and at the cutter head, cement mortar being passed through the central flushing bore of the anchor at the start of boring, which cement mortar fills the bore in synchronism with the advance of the same and ensures large-volume penetration of the surrounding rock in each case. In this way, reliable and stable positioning of an anchor can be achieved by conventional machine use, even under difficult conditions, namely in the rock mentioned. …IMAGE…