ROCKBOLT

Abstract A rockbolt for installation in a bore in the roof of an underground excavation, such as a tun-nel or mine, to support the roof, comprises a sleeve having a closed top and ports in its upper end, a plunger slideably mounted in the sleeve, and harden-able binder material encapsulated in burstable cart-ridges in the sleeve above the plunger. The rockbolt is inserted into the bore and the plunger is operated either mechanically or by the application of pressur-ized fluid to the plunger, to extrude the binder material to secure the rockbolt in the bore. A mech-anical anchor can be provided on the top of the sleeve so the rockbolt can be tensioned before the binder sets. Alternatively, faster setting binder can be provided in -the sleeve below the balance of the binder so that it is the last to be extruded and remains near the top to secure the top to the sur-rounding rock before the balance of the binder sets so that the rockbolt can be tensioned before the bal-ance of the binder sets.