Fracture Distribution Characteristics of Mining-induced Overburden in Thick Coal Seam and Pressure Relief Gas Extraction Technology

Abstract

Aiming at the safety problem of high gas emission in 2303 fully mechanized caving face of Cuijiagou Coal Mine, the evolution law of “three zons” in goaf is studied by using physical similarity simulation and UDEC numerical simulation experiment on the basis of analyzing the failure characteristics of overlying rock in fully mechanized caving mining of extra thick coal seam. The mathematical model of mining fracture elliptical paraboloid zone is established, the favorable area of overburden fracture gas extraction is determined, and the gas extraction scheme of low-medium-high drilling phase combination is proposed, and the engineering application is carried out. The results show that the height of the 2303 fully mechanized caving face is 33 m, the fracture zone height is 110 m, the range below 55 m of the coal seam floor and the outer elliptical set is the favorable area of gas extraction, and the gas concentration in the upper corner is less than 0.6% through the implementation of the low-medium-high drilling extraction scheme. The gas concentration in the return lane is less than 0.5%, which effectively guarantees the safe and efficient recovery of the working face.

Keywords

• fully mechanized caving face
• mining-induced overburden fracture
• udec software
• high borehole
• gas extraction