A new method for determining coal seam permeability redistribution induced by roadway excavation and its applications.

• A new method for directly determining the coal seam permeability around roadway is proposed. • The coal seam permeability around roadway is divided into four stages. • The results are able to determine the sealing depth of in-seam borehole and guide the gas disaster preventions. Changes in coal seam permeability induced by roadway excavation may lead to many engineering problems, such as low gas extraction concentration in in-seam boreholes, coal and gas outburst disasters, and gas emissions in the process of coal roadway excavation. To solve these problems, this paper proposed a new method to directly determine the distribution of coal seam permeability around roadways. For this purpose, method principle was analyzed, equipment was developed, and field experiments were carried out in Baiyangling coal mine. Finally, the engineering applications of the method were analyzed, and a field application effect experiment was conducted to verify the new method. The results showed that the coal seam permeability around roadways was divided into four stages. In stages I and II, permeability increased, in stage III, permeability decreased, and stage IV maintained the initial permeability of the coal seam. These test results will aid in increasing the gas extraction concentration of in-seam boreholes and will guide the design of gas control areas. Using the verification experiment, it was concluded that the new method is able to accurately determine the redistribution of coal seam permeability caused by roadway excavation and provide theoretical guidance in solving engineering problems. [ABSTRACT FROM AUTHOR]