Research on controlling gas overrun in a working face based on gob-side entry retaining by utilizing ventilation type...

Area of Science:

• Mining Engineering
• Computational Fluid Dynamics
• Ventilation Systems

Background:

• Gob-side entry retaining with roof cutting and pressure relief is crucial for mine stability.
• Understanding air leakage characteristics is vital for effective ventilation and gas control in mining operations.
• High gas concentration (GC) in the goaf poses significant safety risks during coal mining.

Purpose of the Study:

• To analyze air leakage patterns in "Y" type ventilation systems during gob-side entry retaining.
• To investigate the relationship between gob-side entry retaining length and air leakage volume.
• To determine optimal gas extraction strategies for controlling gas accumulation in mined-out areas.

Main Methods:

• Computational Fluid Dynamics (CFD) simulations were employed to model "Y" type ventilation.
• Gauged parameters from a working face (WF) in the Daxing coal mine were used for simulation.
• Gas concentration and air leakage were simulated under various conditions, including different gas extraction methods.

Main Results:

• Air leakage flows from gob-side entry retaining to the goaf, with lowest air pressure (1.12 Pa) at the upper corner of the WF.
• Air leakage volume positively correlates with gob-side entry retaining length, peaking at 247 m³/min.
• Optimized gas extraction using buried pipes (4.0 m depth, 400 mm diameter) reduced upper corner GC to 0.37%.

Conclusions:

• Roof cutting and pressure relief create an open goaf, influencing air leakage dynamics.
• Specific gas extraction strategies, including high-level boreholes and targeted systems, effectively resolved gas overrun issues.
• The study provides a theoretical foundation for controlling gas overrun and ensuring secure production in mines.