A resin anchored rock bolt with a locating formation at a leading end

Abstract

Disclosed is a centralising positioner for a resin bolt which includes a central attachment part which is adapted to engage a leading end of the bolt and a positioning part integral with the attachment part that extends from the attachment part.

Description

BACKGROUND OF THE INVENTION[0001]This invention relates to a rock bolt for use in a resin anchored application.[0002]It is well known in the art to anchor a rock bolt into a rock hole with a grout or a two-part resin. The grout or resin is introduced into the rock hole, ahead of the bolt, by means of grout or resin capsules.[0003]The rock bolt has to be adapted to puncture the capsule to release the contents. With the two-part resin, the contents have to be thoroughly mixed to achieve optimal setting.[0004]Strictly, the resin is not an adhesive as it does not adhere the rock bolt to the rock hole. The resin mechanically locks the rock bolt in the rock hole. Thus, there is a reliance upon mechanical interlock with irregularities in the surface of the rock bolt and the rock hole walls to prevent the rock bolt from being pulled from the rock hole. The irregularities on the surface of the rock bolt are provided by a profiled surface.[0005]Another factor influencing optimal mechanical lo...

AI Technical Summary

Benefits of technology

The invention provides a centralising positioner for a resin bolt that includes a central attachment part and a positioning part. The attachment part may be a disc-shaped part, and the positioning part may be a circumscribing umbrella formation or a plurality of locating fingers. The positioner may be made from metal or plastics material and may have a penetrating formation or a conical leading end. The technical effect of the invention is to provide a reliable and secure attachment for resin bolts in rock formations, ensuring proper positioning and stability during use.

Problems solved by technology

This means that the larger the ratio between the diameter of rock hole and the rock bolt, i.e. the larger the annular space between the rock bolt and the rock hole wall, the greater the mixing inefficiency towards an outer circumference of the annular space.

Potentially, this reduces the load bearing capacity of the rock bolt.

Unfortunately, the functions are not complementary.

Optimising the mixing features tends to decrease the anchoring abilities of the bolt.

Gloving is another problem in resin bolting.

Yet another issue in resin bolting is that the rock bolt is very rarely inserted in complete co-axial alignment with the rock hole causing eccentricity of the bolt to the rock hole, about the distal end of the bolt.

In the thin annular arc there is insufficient resin to provide optimal mechanical interlock.

Whilst in the thick annular arc, the resin is insufficiently mixed.

And with insufficient resin in the small annular arc, the protective barrier provided by the resin is thinned, increasing the chance of acid mine water penetrating to the rock bolt.

Both eccentricity and gloving tends to occur in the critical top of the leading end section of the installed bolt.

Images