Self Drilling Rock Bolt With Reinforcing Strands
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional self-drilling rock bolts are costly due to the use of hollow steel bars or high-strength pipes, and they often have reduced bonding with the borehole walls, which affects their tensile strength and stability in underground mining applications.
Innovation Solution
A rock bolt design featuring a hollow tubular member reinforced with metal strands or prestressed concrete wire, which provides a deformed outer surface for enhanced bonding with the borehole walls, allowing for pre-stressing and high tensile strength while being more economical than traditional materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hollow steel bars are used as self-drilling rock bolts, then the rock bolt can achieve high tensile strength, but the manufacturing cost becomes quite high
Solution Approach 1:
The invention uses a composite structure combining a hollow tubular member (steel or other strong material) with external reinforcing strands (prestressed concrete wire or steel). This composite approach allows the rock bolt to achieve high tensile strength comparable to solid high-strength steel bars while using more economical materials, as the hollow tube provides structural integrity and the external strands provide additional reinforcement without requiring expensive high-density steel throughout the entire bolt length.
2Ease of operation
If an outer sleeve is added to a solid rebar for water passage, then water passage during drilling is enabled, but the bonding between the rebar and the bore hole wall is reduced
Solution Approach 1:
The invention employs a hollow tubular member that serves as both the structural core and the water passage conduit. The tubular design allows water to flow through the center during drilling operations, while the external reinforcing strands are placed directly against the borehole wall to ensure strong bonding. This eliminates the need for an outer sleeve that would interfere with bonding, as the hollow tube itself provides the water passage function without compromising the bond between the reinforcing strands and the rock.
3Strength
If high strength pipe is used for self-drilling rock bolts, then the rock bolt achieves sufficient strength, but the material is expensive and difficult to manufacture in the required high strength material
Solution Approach 1:
The invention divides the rock bolt into two functional segments: a hollow tubular member providing the basic structural framework and water passage, and separate reinforcing strands providing additional strength. This segmentation allows each component to be manufactured from materials optimized for its specific function, rather than requiring the entire bolt to be made from expensive high-strength material. The hollow tube can be made from standard strength materials, while only the critical reinforcing portions use high-strength prestressed concrete wire or steel strands.
Data Source
AI summary
The present invention relates to a self drilling rock bolt which may be used in mining applications. Self drilling rock bolts are typically formed by rebars having an axially extending central passageway for water passage and post grouting. Costs of such hollow steel rebars is quite high. In the present invention, a rock bolt is formed from a hollow tubular member which may be steel pipe, and a reinforcing arrangement comprising prestressed concrete type steel strand wound around the outside of the hollow tubular member.