Development Law of Loosing Circle of Layered Surrounding Rock in Coal Mine Roadway

Taking the layered roadway surrounding rock of Zhijin Coal Mine in Guizhou Province as the research object and using acoustic velocity mutation to judge the range of the surrounding rock loosing circle, the straight wall arch section and circular arch section are tested by multiple samples, the limit of roadway loosing range is determined, and the range of loosing circle of each type of roadway is analyzed statistically, and the development law is revealed. The results show that the loosing range of the inclined side wall and the vault roof decreases gradually, while the loosing range of the anti-inclined side wall increases gradually until the loosing range of the two sides is approximately the same. The loosing range of different parts of the roadway is obtained, and the development law diagram of the loosing circle at different angles is drawn. The excavation design and the technical key points of support for the loosing circle of surrounding rock in layered roadway are proposed.