GB1340543A - Remote installation of rock bolts - Google Patents

Abstract

1340543 Anchor bolts C I WILLIAMS 30 July 1971 [3 Aug 1970] 36079/71 Heading F2H An anchor bolt to be secured in a hole 27 comprises a rod 25 having threaded end portions, a wedge member 32 in threaded engagement with one of the end portions and at least partially surrounded by an expansible shell 34, and an arrangement which prevents the wedge member 32 from being unthreaded from the rod and which limits movement of the shell 34 axially of the rod. This arrangement may comprise an enlargement 38, 39 or a hole accommodating a cross-pin 40 (Fig. 8, not shown) at the lower extremity of the rod 25 and also a thrust plate 35 attached to the rod 25. Slip rings 36 may be provided between the shell 34 and the thrust plate 35. In use, the anchor bolt is secured in a hole 27 in the sea-bed from a vessel vertically above the hole by (a) inserting the rod into the hole using an actuating rod (23) (Fig. 1, not shown) which is in temporary screw-threaded connection with the rod 25, (b) expanding the shell 34 into engagement with the wall of the hole 27 by clockwise rotation of the rods 23, 25 to urge the wedge member 32 vertically relative to the shell 34 and rod 25, (c) introducing fluid cementitious material into the hole 27 via a passage extending longitudinally of the rods 23, 25 and opening at the surface of the rod 25 at 37, and then, before the cementitious material sets, (c) back-rotating the actuating rod 23 initially to withdraw to a limited extent the rod 25 from the hole until the enlargement 38, 39 (or cross-pin 40) abuts the shell or wedge member (Fig. 6, not shown) and subsequently to unscrew the actuating rod 23 from the bolt rod 25. When the cementitious material has set an eye-nut (Fig. 11, not shown) may be attached to the free end of the anchor bolt.