Encapsulation system and method of installing a rock bolt

#The present invention relates to the field of strata control in civil engineering and mining operations, and in particular relates to a method of installing a rock bolt to secure the roof or wall of a mine, tunnel or other ground excavation and an encapsulation system for use in such a method.

#Rock bolts are utilised to secure the roof or walls of an underground mine, tunnel or other ground excavation by inserting the rock bolt into a bore hole drilled in the face of the rock to be secured and securing the rock bolt within the hole. Rock bolts have an elongate load bearing element, which is typically either in the form of a rigid steel bar or in the form of a cable bolt (sometimes called a strand bolt) comprising a plurality of wires helically wound into the form of a cable/strand.

#One known means for securing the rock bolt into a bore hole is with the use of an encapsulation medium in the form of a resin. After first drilling a bore hole into the rock face, a sausage-like two-component resin filled cartridge is inserted into the bore hole, followed by a rock bolt which pushes the resin filled cartridge toward the blind end of the bore hole. The rock bolt is typically rotated by the installation rig as it is thrust upwardly, shredding the frangible cartridge casing and mixing the resin components as the rock bolt is thrust toward the blind end of the bore hole. Rotation of the rock bolt is then stopped for a few seconds to allow the mixed resin to cure.

#Preferred embodiments of the present invention will now be described, by way of examples only, with reference to the accompanying drawings wherein:

#FIG. 1 is an isometric view of an encapsulation system according to a first embodiment;

#FIG. 2 is a cross section or front elevation view of the encapsulation system of FIG. 1 inserted into a bore hole;

#FIG. 1 depicts an encapsulation system 100, for use in securing a rock bolt in a bore hole drill into a rock face to be stabilised, according to a first embodiment. The encapsulation system 100 comprises at least two, and here three, separate encapsulation mediums and three elongate cartridges containing the encapsulation mediums. Specifically, the encapsulation system 100 of the first embodiment comprises a first cartridge 110 having a frangible casing 111 and containing a first encapsulation medium 112, a second cartridge 120 having a frangible casing 121 and containing a second encapsulation medium 122 and a third cartridge 130 having a frangible casing 131 and containing a third encapsulation medium 132. Each of the cartridges 110, 120, 130 is of a relatively standard sausage-like configuration, with the casing 111, 121, 131 comprising a heat-sealed tube of polyester film with a clip sealing each end of the casing 111, 121, 131.

#The first encapsulation medium 112 comprises a curable first resin formulation, typically being a two-part resin formulation consisting of a curable component (commonly referred to as a “resin mastic”) and a catalyst component (commonly referred to as a hardener). When mixed with the curable component, the catalyst component causes a chemical reaction curing the resin. The casing 111 of the first cartridge 110 is separated into two compartments by a polyester film (not shown) extending along the length of the casing 111, with the curable and catalyst components of the resin formulation being contained in the separate compartments.

#The third encapsulation medium 132 comprises a curable third resin formulation. The third resin formulation is typically of a similar formulation to the first resin formulation, but may have a longer curing time. It is also envisaged that dissimilar resin formulations may be utilized. The casing 131 of the third cartridge 130 is typically identical to, or at least substantially identical to, the casing 111 of the first cartridge 110, again being separated into two compartments by a polyester film extending along the length of the casing 131, with the curable and catalyst components of the resin formulation being contained in the separate compartments.