Fractured Roof Mining Entry Anti-Collapse Structure
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Solution Overview
Problem
In longwall mining, the traditional method of retaining coal pillars for support results in resource wastage and low efficiency, while non-pillar mining methods face significant challenges due to periodic roof pressure, which can lead to destructive forces and accidents.
Innovation Solution
The fractured roof mining method employs an entry-side anti-collapsed structure with an arch-shaped roof and directional cutting at a 15-20 degree angle, using constant resistance anchor rods, common anchor rods, anchor cables, and composite mesh for support, along with H-shaped steel props and temporary props to manage pressure and prevent gangue fall.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If non-pillar mining is used to save coal resources, then resource waste is reduced, but periodic roof pressure creates destructive forces and safety risks
Solution Approach 1:
The roof is segmented through directional cutting at 15-20 degrees on one side of the roadway, creating controlled fracture zones that redirect periodic pressure away from the entry. This segmentation allows the roof to break in a predetermined pattern rather than creating uncontrolled periodic pressure on the working face.
Solution Approach 2:
A composite mesh for gangue prevention is introduced as an intermediary structure between the roof and the roadway. This mesh acts as a mediator that distributes and absorbs periodic roof pressure, preventing direct transmission of destructive forces to the entry while maintaining resource efficiency through non-pillar mining.
2Reliability
If traditional 121 mining method with coal pillar is used, then roadway support is ensured, but coal resources are wasted and work efficiency is reduced
Solution Approach 1:
The coal pillar is completely removed through non-pillar mining, extracting this non-productive element from the system. The entry is then reinforced with arch-shaped roof design and composite mesh support, allowing full extraction of coal resources while maintaining roadway stability through alternative support mechanisms.
Solution Approach 2:
The roadway cross-sectional parameters are changed by forming an arch-shaped roof with specific curvature radii (R1=1.5-2.5m, R2=3-5m). This geometric parameter change optimizes the distribution of roof pressure, enabling the roadway to withstand loads without requiring a coal pillar, thus improving mining efficiency while maintaining support reliability.
3Reliability
If arch-shaped roof with directional cutting is implemented, then entry stability is improved, but construction complexity increases
Solution Approach 1:
The roadway roof is designed with arch-shaped curvature consisting of two circular arc segments. This curved geometry naturally distributes roof pressure along the arch form, improving entry stability. The curvature parameters (radii R1 and R2) are optimized to balance structural performance with construction feasibility, using standard tunneling machinery capabilities.
Data Source
AI summary
A fractured roof 110 mining method entry-side anti-collapsed structure, one working face of the 110 mining method corresponds to one roadway but without retaining any coal pillar, the roadway retains an entry after the previous working face implements mining top-cutting pressure release, and a roof of the roadway is arch-shape, directional cutting is conducted on one side of the roadway, and the cutting angle is between 15-20 degrees. One working face corresponds to one roadway but without retaining any coal pillar when underground mining is conducted, which can save resources and improve recovery rate of mining. And, the roof of the roadway of the retained entry is arch-shaped, which can improve safety and ensure safety of the coal mining working face. In addition, a cutting angle is 15-20 degrees, which can effectively determine a roof caving direction after top-cutting and reduce affect to the retained entry.