Non-pillared Longwall Mining Method for Goaf-side Entry Retaining
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Solution Overview
Problem
Traditional longwall mining methods face challenges such as high engineering quantities, low production efficiency, resource waste, and safety hazards like gas outbursts and rock bursts due to increased ground stress, especially in deep mining, where pillar-supported roadways are used, leading to inefficient and unsafe mining processes.
Innovation Solution
A non-pillared mining method involving the excavation of two communicating roadways, reinforcement of the top panel with energy collecting holes for pre-splitting blasting, forming a directional kerf, and allowing the top panel to collapse, creating a new roadway that can be reused as a tailentry for subsequent mining faces, utilizing an anchor rod with constant resistance and large deformation for support, and real-time monitoring with sensors to ensure safety and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If retained pillars are used to protect tailentry roadway in deep coal mining, then roadway stability is improved, but mining efficiency deteriorates and resource waste increases
Solution Approach 1:
The invention removes the retained pillars from the mining system entirely. By using goaf-side entry retaining technology, the tailentry roadway is driven directly into the goaf space without requiring pillar support, extracting the harmful element (pillars) that caused resource waste and efficiency loss while maintaining roadway stability through alternative means.
Solution Approach 2:
The invention introduces goaf-side entry retaining as an intermediary solution between traditional pillar-supported roadways and completely unsupported roadways. The retaining system uses active support technology and coordinated roadway side support to stabilize the tailentry roadway without requiring pillars, mediating between the need for stability and the desire for high efficiency.
2Reliability
If roadway width is increased to accommodate retained pillars, then roadway stability is improved, but resource waste increases
Solution Approach 1:
The invention extracts the pillar structure from the roadway support system. By driving the tailentry roadway directly into the goaf space and using active support technology, it eliminates the need for wide roadways dedicated to pillar accommodation, thereby recovering coal resources that would otherwise be wasted in pillar areas.
3Loss of substance
If traditional goaf-side entry driving is used, then resource waste is reduced, but production efficiency deteriorates due to long waiting time
Solution Approach 1:
The invention performs preliminary action by driving the tailentry roadway into the goaf space during the mining process itself, rather than waiting until after the working face is completely extracted and the top panel is fully caved. This allows roadway formation to occur in advance, eliminating the long waiting period and enabling continuous production.
Solution Approach 2:
The invention ensures continuity of useful action by allowing the tailentry roadway to be formed and used continuously during the mining process. The roadway is driven into the goaf space as mining progresses, eliminating idle time and maintaining continuous production flow without the interruptions characteristic of traditional goaf-side entry driving.
4Reliability
If active roadway support technology is increased, then roadway stability is improved, but device complexity increases
Solution Approach 1:
The invention segments the roadway support system into distinct functional components: active support technology for the tailentry roadway, roadway side support for the goaf-side entry, and coordinated support mechanisms. This segmentation allows each component to be optimized independently, managing complexity while achieving high stability.
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
This method enables continuous and safe coal seam mining without pillars, reducing the time required for roadway formation and enhancing mining efficiency by maintaining the stability of the top panel and surrounding rocks, thus addressing the inefficiencies and hazards of traditional methods.
Implementation Method 1
blasting at a position corresponding to the energy collecting holes on the top panel of the original headentry of the goaf, and forming a directional kerf
Implementation Method 2
drilling on the working face side of the top panel of the headentry a plurality of energy collecting holes for pre-splitting blasting
Implementation Method 3
making the top panel of the mining face collapse by the pressure from a deep stratum on an upper portion of the goaf
Implementation Method 4
making the top panel of the mining face collapse by the pressure from a deep stratum
Implementation Method 5
An anchor rod with constant resistance and large deformation is adopted
Implementation Method 6
An anchor rod with constant resistance and large deformation is adopted
Implementation Method 7
mounting a sensor on the top panel of the headentry, and wire-transmitting signals to the ground for remotely real-time monitoring of the status of the headentry
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Disclosed is a longwall working face, non-pillared mining method, comprising the following steps: 1. Excavating a tailentry (2) and a headentry (3); 2. Reinforcing a top panel (5) of the tailentry (3) and drilling on the top panel an energy collecting hole (7) for pre-splitting blasting; 3. Extracting until a goaf is formed; 4. Blasting at a position corresponding to the energy collecting hole and forming a kerf on the top panel; 5. The mining face collapsing to become a new roadway; 6. Taking the original headentry as the tailentry of the next mining face, and excavating a headentry relative to the tailentry, to form a new mining face; and 7. Repeating steps 2-6, and continuing to mine coal until the coal seam mining is completed. The present method involves continuity between every two mining faces, non-pillared support, a short process for forming roadways, and high efficiency of mining and forming roadways.