METHOD FOR DESIGNING WIDTH OF ISOLATION COAL PILLAR AND GASIFIER IN UNDERGROUND GASIFICATION UNDER AQUIFER FACING OVERLYING STRATA

摘要

Disclosed is a method for designing the width of an isolation coal pillar and a gasifier in underground gasification under an aquifer facing an overlying strata, which is suitable for the design of coal mining by underground gasification under the overlying stratum aquifer. The method comprises: firstly, determining the maximum height of a waterproof coal-rock pillar according to the position of an aquifer; calculating the thickness of a protective layer of the area to be gasified, and determining a development limit value of a water-flowing fracture zone of the gasified area; establishing a strip mining-surface mining retreating-type gas injection control underground gasification numerical model, and determining the relationship between the development height of a strip mining-surface mining retreating-type gas injection control underground gasification water-flowing fracture zone and the width of the gasifier and the isolation coal pillar; and selecting, in combination with the relationship between the development height of the water-flowing fracture zone and the width of the gasifier and the isolation coal pillar, the width of the gasifier and the isolation coal pillar for the strip mining-surface mining retreating-type gas injection control underground gasification, thereby completing the safe production design for the strip mining-surface mining retreating-type gas injection control underground gasification under the overlying stratum aquifer. The method is simple in terms of steps, and can ensure the optimal gasification production benefit on the premise of ensuring the stability of the overlying aquifer and the safe production of underground gasification.