Characteristics of Airflow Migration in Goafs under the Roof-Cutting and Pressure-Releasing Mode and the Traditional Longwall Mining Mode.

The airflow exchange between a mining face and a coal mine goaf can cause gas transfinite and spontaneous coal combustion disasters, threatening coal mining. Studying the characteristics of airflow movement in a goaf forms the basis to prevent airflow exchange for coal mining safety. Different from the traditional longwall mining mode, the roof-cutting and pressure-releasing mining mode shows new roof collapse characteristics and a ventilation system, which lead to obvious changes in the characteristics of airflow movements in coal mine goafs. To study the differences in airflow movement characteristics and the airflow disturbance influence area in a coal mine goaf between these two mining modes, the airflow movements in different goafs are compared using a numerical simulation method based on the measured parameters of the 1201 mining face in the Halagou Coal Mine, China. The results show that the airflow disturbance area in the goaf under the traditional longwall mining mode is a "η" type. Along the inclination direction of the mining face, two main exchange areas for the airflow are located in the 0-5 and 15-45 m sections, respectively. The airflow disturbance area in the goaf under the roof-cutting and pressure-releasing mining mode is a "hump" type, and there are six main exchange areas in the goaf under the roof-cutting and pressure-releasing mining mode. Along the inclination direction of the mining face, three exchange areas are located in the 0-25, 255-305, and 305-320 m sections, respectively. Along the strike direction, three exchange areas are located in the 5-25, 25-35, and 35-65 m sections, respectively. Based on the research results, sealing measures are taken to slow and eliminate airflow exchange in the goaf under the roof-cutting and pressure-releasing mining mode, and this provides theoretical guidance for safe coal mining.