Shear and tensile reinforcement for inflatable bolt

Abstract

An inflatable rock bolt including an expansion tube, a bushing arranged at each end of the expansion tube, and at least one reinforcing member arranged outside the expansion tube. The at least one reinforcing member includes at least one of a strand extending along the expansion tube or a sleeve at least partially surrounding the expansion tube. A method for reinforcing an inflatable rock bolt.

Description

FIELD OF THE INVENTION[0001]The invention relates inflatable rock bolts. In particular, the invention relates to reinforcement for inflatable rock bolts. The invention also relates to a method for reinforcing an inflatable rock bolt.BACKGROUND OF THE INVENTION[0002]Rock is removed from the ground in a number of contexts, such as in mining and tunnel construction. Voids, or cavities, are created by the removal of the rock. Underground voids formed by removing material leaves walls and ceilings of surrounding rock. The remaining surrounding rock is subject to gravity and without the removed material to support the surrounding material may tend to converge. Convergence is the decrease of tunnel size caused by gravity and relieving residual ground stresses. Controlling convergence is a critical safety activity.[0003]One technique for controlling convergence includes drilling holes in the surrounding material and anchoring bolts in the material to reinforce and stabilize the material. Ro...

AI Technical Summary

Benefits of technology

The invention is an inflatable rock bolt that includes an expansion tube, bushing, and reinforcing members. The reinforcing members can be strands or sleeves that extend along the expansion tube and are inserted into a hole. The expansion tube is expanded, frictionally clamping the reinforcing members between the expansion tube and the wall of the hole in which the bolt is inserted. The technical effects of the invention include increased stability and reinforcement of the rock bolt, making it more durable and reliable.

Problems solved by technology

The remaining surrounding rock is subject to gravity and without the removed material to support the surrounding material may tend to converge.

If ground convergence exceeds the elongation limit of any of the rock bolts, they will fracture.

If a bolt or group of bolts fail and no longer constrain a given mass of rock, that mass will fall into the void with the potential to cause injury or death and property damage.

Though this device has high tensile capacity and installation time is low, one drawback is that the shear strength and stiffness of the inflation tube may be poor compared to other ground control devices that use solid profiles and grout and / or resin to create the bolt / ground interlock.

However, it is inherent that an inflatable material is thin to have the ability to be inflated and create a compression field in surrounding rock and a friction interface along its length.

This will make it difficult to insert and accommodate a reinforcing structure within the inflatable bolt, particularly if the reinforcing member is round.

Additionally, inflatable bolts have a complex shape that is formed in many stages.

This makes it difficult if not impossible to form the bolt around the reinforcing structure, particularly for high volume production.

Additionally, inserting a reinforcing member within the inflatable bolt would be difficult if not impossible, due to the length of the bolts.

For example, the reinforcing member could easily be jammed within the bold during insertion, leaving it only partially inserted.

Furthermore, securing a reinforcing member inserted into an inflatable bolt would be difficult.

This would be impractical or impossible for welding equipment to be inserted into the bolt.

The chemical composition of hardened material does not react well to the welding process.

As a result, the bolt would not inflate properly.

Since the bolt would be inserted into a hole at this stage, the installer would have no indication that the bolt is not properly inflated.

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