Cable Bolt Supporting Tube Prevents Buckling

Solution Overview

Problem

The installation of cable bolts in underground excavations is hindered by cable buckling and incomplete resin mixing due to the flexible nature of the cables, posing challenges for both the installer and the stability of the bolt.

Innovation Solution

A cable bolt design featuring a supporting tube and tensioning tube with a tapered stopper to prevent buckling, combined with an insertion nut and sealing gasket, facilitates controlled insertion and mixing of resin capsules, ensuring secure anchoring and reduced risk of injury.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a flexible multi-strand steel cable is used for cable bolts, then the cable can be inserted into the bore hole and anchored to the rock formation, but the cable buckles during installation and resin mixing is incomplete

Engineering Contradiction:

Improvecable flexibilityVSAvoidresin mixing completeness

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The cable is divided into multiple strands that are individually grouted into the bore hole. This segmentation allows each strand to be properly positioned and grouted, ensuring complete resin mixing and anchoring while maintaining the overall flexibility of the cable structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Resin is pre-loaded into capsules that are positioned within the bore hole before cable insertion. The cable strands are then inserted to pierce and mix the pre-positioned resin capsules, ensuring complete mixing without requiring the entire cable to be rigid during the grouting process.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If a flexible multi-strand steel cable is used for cable bolts, then the cable can be anchored to the rock formation, but incomplete resin mixing occurs during installation

Engineering Contradiction:

Improveanchor retention strengthVSAvoidresin mixing completeness

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The cable is divided into multiple strands that are individually grouted into the bore hole. This segmentation allows each strand to be properly positioned and grouted, ensuring complete resin mixing and anchoring while maintaining the overall flexibility of the cable structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The resin capsules contain a pigment that changes color when mixed with the cable strands. This visual indication confirms complete mixing and proper anchoring, ensuring reliable retention strength without requiring complex measurement equipment.

Inventive Principle:

Principle #32Color changes

3Stability of the object's composition

If a rigid structure is used to prevent cable buckling, then cable stability during installation is improved, but the cable flexibility and ease of insertion are reduced

Engineering Contradiction:

Improvecable stability during installationVSAvoidcable insertion ease

Core Design Contradiction:

Stability of the object's compositionVSEase of operation

Solution Approach 1:

The cable is divided into multiple strands that are individually grouted into the bore hole. This segmentation allows each strand to be properly positioned and grouted, ensuring complete resin mixing and anchoring while maintaining the overall flexibility of the cable structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cable uses a flexible outer covering that maintains strand alignment during insertion while allowing the cable to bend and navigate the bore hole. This flexible protection is removed or opened at the anchoring zone to allow resin penetration and mixing.

Inventive Principle:

Principle #30Flexible shells and thin films

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The design effectively prevents cable buckling and ensures complete resin mixing, enhancing the stability and secure anchoring of the cable bolt within the excavation, improving safety and installation efficiency.

Implementation Method 1

a tapered stopper which is insertable into the tensioning tube and inside an unbonded, untwisted or unbraided section of the cable to press the unbonded, untwisted or unbraided section of the cable against an interior surface of the tensioning tube

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 2

the supporting tube has a length which is sufficient to substantially prevent cable buckling when the cable bolt is driven into the hole by the drive tool

Methodology Applied

Scientific EffectStructural support:

Implementation Method 3

an adapter for receiving a drive tool for rotationally driving the cable bolt into a hole

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 4

One or more frangible resin capsules are then inserted as far as possible into the hole. The cable bolt is then inserted into the hole such that the cable pierces the resin capsules. Each resin capsule may comprise two or more components in separate compartments which solidify when they are mixed

Methodology Applied

Scientific EffectSolidification: Freezing

Data Source

PatentEP2395198B1Cable bolt

Publication Date: 2017.09.20 MINOVA INT LTD

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Figure 2

AI summary

This invention relates to a cable bolt (1) for use in rock bolting and a method for its installation. The cable bolt (1) comprises a cable (5), a supporting tube (55) surrounding part of the cable (5), and an adapter (20) for receiving a drive tool for rotationally driving the cable bolt (1) into a hole. The supporting tube (55) has a length which is sufficient to substantially prevent cable buckling when the cable (5) is driven into the hole by the drive tool.