Zonal Bolt-Grouting Support for High-Stress Tunnel Deformation
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Solution Overview
Problem
Anchor bolt support fails due to broken structure and lack of anchoring foundation in cataclastic rock masses, leading to large deformations and inadequate grouting material selection in high-stress tunnels, causing safety and economic issues.
Innovation Solution
A zonal bolt-grouting support device with high-strength prestressed anchor bolts, expansion anchoring agents, decoupling materials, and grouting steel pipes, utilizing different grouting materials and techniques to address varying rock conditions, including quick and slow setting cements for shallow and deep grouting, and a reverse anti-skid device to enhance anchoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If anchor bolt support is used in cataclastic rock mass, then support method is simple and widely used, but anchoring effectiveness is poor due to broken structure and lack of anchoring foundation
Solution Approach 1:
The support system is segmented into multiple functional components: anchor bolts for mechanical anchoring, grouting materials for chemical bonding, and expansion agents for physical expansion. This segmentation allows each component to address specific aspects of the broken rock mass problem, with grouting filling fractures and expansion agents creating anchoring foundations in the absence of natural anchoring zones.
Solution Approach 2:
The invention uses composite support mechanisms combining mechanical (anchor bolts), chemical (grouting materials), and physical (expansion agents) elements. The grouting materials and expansion agents work together to create a composite anchoring foundation that compensates for the broken rock structure, enabling reliable anchoring where natural foundations are absent.
2Strength
If grouting reinforcement method is used, then surrounding rock can be strengthened, but grouting effect is reduced due to blind selection of grouting materials without considering rock nature
Solution Approach 1:
The invention applies different grouting materials and expansion ratios at different locations and depths. Shallow grouting uses different materials than deep grouting, and expansion agents with varying expansion rates are placed at different positions along the anchor bolt. This local differentiation ensures optimal performance for each specific rock condition without requiring blind selection of materials.
Solution Approach 2:
The invention changes key parameters of the grouting system including expansion ratio, grouting material composition, and injection pressure based on depth and rock conditions. Expansion agents with different expansion rates are used at different depths, and grouting materials are selected based on their setting times and flow characteristics to match specific rock fracture patterns.
3Ease of operation
If uniform expansion anchoring agent is used in anchor bolt, then installation is simple, but anchoring foundation is insufficient due to varying rock conditions at different depths
Solution Approach 1:
The anchor bolt is divided into multiple zones with different expansion agents placed at head, middle, and tail sections. Each zone contains expansion agents with expansion rates matched to the local rock conditions, creating zonal anchoring that addresses varying rock quality at different depths while maintaining a relatively simple installation process.
4Productivity
If quick setting cement grouting material is used for shallow grouting, then grouting speed is fast with setting time not more than 10 minutes, but deep grouting requires different material properties
Solution Approach 1:
Different grouting materials with different setting times are used for shallow and deep grouting. Quick-setting materials are applied in shallow zones where rapid stabilization is needed, while slow-setting materials are used in deep zones where longer fluidity is required to penetrate distant fractures. This local differentiation optimizes both grouting speed and material compatibility.
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
Enhances anchoring effectiveness by forming a solid foundation, reducing deformation, and adapting to varying rock conditions, thereby improving safety and structural integrity in high-stress tunnels.
Implementation Method 1
The expansion anchoring agent adopts a hollow structure and is inserted in the anchor bolt, the expansion rate of the expansion anchoring agent at the tail is higher than that of the expansion anchoring agent in the head and middle
Data Source
AI summary
A zonal bolt-grouting support device and method for cataclastic rock mass large deformation of a high-stress tunnel, the method includes: drill holes in surrounding rock of a tunnel against a tunnel face after rock mass excavation, install high-strength prestressed anchor members, apply a preload to anchor bolts when expansion anchoring agent is fully expanded and has a certain strength, and zonally grout the surrounding rock after stress adjustment. The high-strength prestressed anchor member comprises an anchor bolt, an expansion anchor agent, a decoupling material, a grouting device, a reverse anti-skid device, etc. The grouting device consists of a shallow grouting steel pipe, a deep grouting steel pipe and a grouting stop valve, and the grouting steel pipe is arranged side by side with the anchor bolt in a drill hole. The technical proposal of the invention effectively inhibits the large deformation of a cataclastic rock mass.