Grouting Anchor Bolt for Large Deformation Roadway Support
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Solution Overview
Problem
Traditional anchor bolts and cables are ineffective in supporting deep underground roadways due to their inability to adapt to large deformation, leading to frequent breakage and increased pressure, and existing solutions for large-deformation supporting are costly and inefficient.
Innovation Solution
A grouting anchor bolt and cable system with a casing, hollow rod or steel cable, anchor cylinder, tray, fastening nut, and clamping pin, featuring a gradually decreasing inner diameter and fine threads, allowing for constant resistance and energy absorption, combined with a quantitative roadway supporting method that determines optimal energy-absorbing region length and grouting time through numerical simulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional small-deformation anchor bolts are used, then the supporting structure is simple and cost-effective, but the anchor bolts cannot adapt to large-deformation destruction features of surrounding rocks, resulting in breakage and ineffectiveness
Solution Approach 1:
The anchor bolt incorporates a dynamic energy-absorbing mechanism that allows the rod body to yield and deform plastically under large deformation conditions. The yieldable rod body can undergo controlled deformation up to 200mm while maintaining structural integrity, transforming the rigid traditional anchor bolt into a flexible system that adapts to rock movement without breaking.
Solution Approach 2:
The invention changes the mechanical parameters of the anchor bolt by using a yieldable rod body with controlled plastic deformation characteristics. The rod body is designed to yield at specific stress levels, allowing it to absorb energy through deformation rather than fracturing, thus adapting to large deformation while maintaining reliability.
2Adaptability or versatility
If continuous resistance-increasing deforming anchor cable is used, then large-deformation supporting is achieved, but the anchor cable breaks and disabled due to increasing supporting resistance, and grouting cannot be achieved
Solution Approach 1:
The anchor bolt uses a dynamic yielding mechanism where the rod body can deform plastically to accommodate large rock movements. Unlike continuous resistance-increasing cables that harden with deformation, this system maintains constant resistance through controlled yielding, preventing cable breakage while enabling grouting operations.
Solution Approach 2:
The invention maintains constant supporting resistance through controlled plastic deformation of the yieldable rod body. The material properties are selected to allow yielding at a specific stress threshold, keeping the supporting force constant rather than increasing continuously, which prevents cable failure and enables grouting.
3Adaptability or versatility
If energy-absorbing anchor bolts are used, then large deformation is accommodated, but roadway self-bearing capability and stability are poor
Solution Approach 1:
The anchor bolt system segments the supporting function into two parts: the yieldable rod body that absorbs energy through deformation, and the grout that provides active support to improve rock self-bearing capability. This segmentation allows the system to simultaneously accommodate large deformation and enhance rock strength through grouting.
Solution Approach 2:
The invention introduces grout as an intermediary substance that fills the space between the anchor bolt and surrounding rock. The grout bonds the rock mass together, improving self-bearing capability and stability, while the yieldable rod body provides the mechanical framework for energy absorption. This intermediary enables both functions to coexist.
4Ease of manufacture
If traditional anchor bolts are used, then installation is simple and costs are low, but parts of the anchor bolts cannot be recovered, resulting in high costs
Solution Approach 1:
The anchor bolt is divided into separable components: the yieldable rod body, anchorage sections, and connecting elements. This segmentation allows the rod body to be recovered and reused after the grout sets, while simplifying installation through modular assembly. The detachable design enables component recovery without complicating the installation process.
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 system provides effective, quantitative support for large deformation in surrounding rocks by improving self-bearing capability and reducing costs through simplified operations and recyclable components, achieving an organic combination of yielding and active-passive support.
Implementation Method 1
an inner diameter of the casing from the middle position of the casing to the rear end becomes small gradually... the anchor cylinder is inserted into the casing and moveably connected with the casing... providing constant resistance
Implementation Method 2
grouting cannot be achieved to change an internal loose structure of surrounding rocks and improve self-bearing capability of the surrounding rocks
Implementation Method 3
an inner diameter of the casing from the middle position of the casing to the rear end becomes small gradually... allowing for constant resistance and energy absorption
Data Source
AI summary
Provided are a grouting anchor bolt and a grouting anchor cable for supporting of large deformation and constant resistance and a quantitative roadway supporting method, wherein an anchor bolt comprises a casing, a hollow rod body, an anchor cylinder, a tray, a fastening nut and a clamping pin, a front end of the casing is sealed and a rear end of the casing is opened, a middle position of the casing is provided with a plurality of grouting holes, an inner diameter of the casing from the middle position of the casing to the rear end becomes small gradually, a side surface of a front end of the hollow rod body is sleeved with an anchor cylinder, the anchor cylinder is inserted into the casing and movably connected with the casing, the anchor cylinder is connected with the casing through the clamping pin, a rear end of the hollow rod body is sequentially assembled and connected with the tray and the fastening nut. The beneficial effects herein are as follows: the anchor bolt and the anchor cable simple in structure, easy to process, simplifies operations of supporting and grouting, and therefore particularly suitable for supporting of large deformation for surrounding rocks. The self-bearing capability of surrounding rocks is improved, and the supporting of large deformation of surrounding rocks is provided through constant resistance, thereby realizing organic combination of “yielding-supporting” and “active-passive supporting”; the quantitative roadway supporting method may realize quantitative supporting for a roadway.