Auxiliary outburst prevention techniques by surface pre-drainage for coalbed exposed in tunnel and mine shaft

How to expose an outburst-prone coal seam safely and efficiently in tunnel and mine shaft is always a subject to study continuously in outburst prevention, surface coalbed gas pre-drainage is an effective approaches for outburst prevention. Based on the analysis of outburst mechanism in tunnel and mine shaft and the core task of outburst prevention, the characteristics and adaptability of the outburst prevention techniques by surface pre-drainage are studied. Practical engineering application shows that the gas content and pressure in coal exposure area can be effectively reduced using surface pre-drainage well by cavern completion or hydraulic fracturing, the stress or pressure relief and the source and driving force of outburst are weakened after drainage, the seam changed from outburst state to non outburst state. Surface pre-drainage of coal gas can effectively reduce the difficulty of underground outburst prevention and improve coal exposure efficiency, therefore, can be used for outburst prevention during coal exposure in cross-cut and shaft with complicated geological conditions.