Expandable Mine Bolt With Internal Reinforcement
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Solution Overview
Problem
Existing expandable rock bolts face challenges with corrosion resistance and strength under tensile and shear forces due to exposure to aggressive environments, where the protective coating can be damaged during expansion and deformation, leading to potential failure.
Innovation Solution
A rock bolt design featuring an internal reinforcement means protected within an external tubular part that expands, maintaining its original form and corrosion resistance, with a sealed end section and end piece to direct pressurized fluid expansion only to the external tubular part, while the reinforcement remains unaffected, enhancing strength and corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the rock bolt is expanded to come into contact with the drilled hole wall, then the anchoring strength is improved, but the protective coating is damaged leading to reduced corrosion resistance
Solution Approach 1:
The rock bolt is divided into two separate tubular parts: an external tubular part that expands to provide anchoring strength, and an internal tubular part that remains unexpanded to protect the reinforcement means. This segmentation allows each part to perform its specific function without compromising the other - the external part provides the necessary expansion for anchoring while the internal part maintains a protected environment for the reinforcement means against corrosion
Solution Approach 2:
The internal tubular part is nested within the external tubular part, creating a protective enclosure. The reinforcement means is placed inside the internal tubular part, which itself is inside the external tubular part. This nested structure ensures that the reinforcement means remains in a protected environment even when the external part expands, preventing coating damage and maintaining corrosion resistance
2Strength
If the rock bolt is expanded to increase anchoring capability, then the load-bearing capacity is improved, but the reinforcement means is exposed to corrosion
Solution Approach 1:
The bolt structure is segmented into functional zones: the external tubular part handles expansion for load-bearing capacity, while the internal tubular part creates a corrosion-protected zone for the reinforcement means. This functional segmentation resolves the contradiction by assigning different roles to different parts
Solution Approach 2:
The internal tubular part acts as an intermediary barrier between the aggressive external environment and the reinforcement means. It mediates the conflict between expansion requirements and corrosion protection by allowing the external part to expand while maintaining a protected internal environment for the reinforcement means
3Reliability
If the protective coating is applied to resist corrosion, then the corrosion resistance is improved, but the coating is damaged during expansion reducing strength
Solution Approach 1:
Instead of applying the protective coating to the entire bolt including the reinforcement means, the invention inverts the approach by placing the reinforcement means inside a protected internal tubular part. The coating is applied only where necessary (external surface), and the reinforcement means is protected by the physical barrier of the internal tubular part rather than relying on coating integrity during expansion
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 rock bolt exhibits increased strength against tensile and shear forces and improved corrosion resistance, as the internal reinforcement absorbs forces and maintains its integrity, extending the bolt's lifespan by preventing deformation and corrosion damage.
Implementation Method 1
The rock bolt is introduced into a drilled hole. The medium is supplied to the interior of the tube, whereby the tube expands to come into contact with the wall of the drilled hole.
Data Source
AI summary
The present invention concerns a tubular rock bolt (1) that can be expanded by a pressurised medium, for insertion into a drilled hole (16) and comprising an extended tubular part (2) with a closed cross-section (12) and provided with a longitudinal stamped part (13) that increases in diameter during the expansion of the rock bolt (1) without the periphery of the tubular part (2) being bent, and an end section (17) at one end (15) of the rock bolt (1) and an end piece (19) arranged at the second end (18) of the rock bolt (1) and provided with a connection part (22) for interaction in a manner that can be released with an expansion means (23). The extended tubular part (2) comprises a reinforcement means (3) that extends internally inside the tubular part (2) between the end section (17) and the end piece (19) and that is attached at the end section (17) and the end piece (19). The invention concerns also the manufacture of a rock bolt.