Deformable Rock Bolt Segmented Anchors for Bursting
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Solution Overview
Problem
Conventional rock bolts are inadequate for highly stressed rock masses as they either fail due to stiffness, low load-bearing capacity, or unreliable anchoring mechanisms, particularly in cases of large deformation and rock bursting.
Innovation Solution
A deformable rock bolt with multiple integrated anchors distributed along its length, allowing for elongation and load distribution, and featuring a threaded portion for pre-tensioning, which enhances anchoring reliability and load-bearing capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional rock bolts are used in highly stressed rock masses, then installation is simple, but they fail due to insufficient deformation tolerance and low load-bearing capacity
Solution Approach 1:
The rock bolt is divided into multiple segments: a deformable stem portion and multiple anchor portions distributed along its length. This segmentation allows the bolt to combine deformation tolerance in the stem with strong anchoring at distributed points, resolving the contradiction between load-bearing capacity and deformation tolerance.
Solution Approach 2:
Different portions of the bolt have different properties: the stem portion is designed to be deformable to accommodate rock movement, while the anchor portions are designed to be strong and rigid for secure anchoring. This local differentiation allows the bolt to simultaneously achieve deformation tolerance and high load-bearing capacity.
2Strength
If stiff rock bolts are used to maintain structural integrity, then load-bearing capacity is maintained, but they cannot withstand large deformations before failure
Solution Approach 1:
The bolt transitions from a static, uniformly stiff structure to a dynamic system where the stem portion can deform elastically under load. The deformable stem acts as a energy-absorbing element that allows the bolt to adapt to varying rock movements while maintaining anchoring strength through the rigid anchor portions.
3Reliability
If anchors are made stronger to prevent failure points, then anchoring reliability improves, but the bolt becomes more susceptible to break at the anchor
Solution Approach 1:
The yield strength parameter is specifically increased for the anchor portions compared to the stem portion. This parameter differentiation ensures that anchors remain the strongest elements in the system, preventing failure at anchor points while allowing the stem to deform and absorb energy, thereby reducing overall bolt breakage susceptibility.
4Reliability
If multiple components are used to form a functioning rock bolt, then anchoring mechanism reliability improves, but device complexity and manufacturing difficulty increase
Solution Approach 1:
Multiple functional components (stem, anchors, and connecting elements) are merged into a single integrated rock bolt structure. This combining approach maintains the reliability benefits of multiple anchoring points while simplifying manufacturing and installation compared to assembling separate components.
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 deformable rock bolt provides improved load-bearing and deformation capacity, with anchors acting as the strongest elements, reducing the risk of failure and maintaining effective rock reinforcement even with partial anchor loss, suitable for both continuous deformation and sudden rock bursts.
Implementation Method 1
said stem portions arranged for slipping relative to the grout or the borehole, so as for each of said stems to constraining local rock deformation through elongation of said stem portions between pairs of a locally anchored preceding anchor and a locally anchored consecutive anchor
Data Source
AI summary
A rock bolt for being grouted in a borehole, —includes an elongate cylindrical massive stem (1) with extensive lengths of stem portions (1s) separated by integrated anchors (2). The anchors are distributed with separations along the length of the stem (1). The anchors (2) are locally anchored relative to their local borehole wall portions for taking up load arising due to rock deformation. The stem portions (1s) are arranged for slipping relative to the grout or the borehole so as for each of the stems (1s) to take up local elongation strain between pairs of locally anchored preceding and consecutive anchors.