Analysis and study on stability when tunnel excavated trough mined-out area

Xiaojiangkou tunnel and Pingdi coal mine were the research objects. According to the geological condition and surrounding rock characteristics of the project site, the stability of mined-out area and its influence on tunnel were studied by numerical simulation method. Corresponding treatment scheme was put forward to provide theoretical support for safe construction and operation of Xiaojiangkou tunnel. Results show that the stability of the point pillars in one or two panel is poorer, so it cannot have long-term effect of roof supporting. Roof caving will occur in part of the mined-out areas. From K line ZK67+555 and D line ZK67 + 466 to the tunnel exit, in 90 mrange, the old mined-out area below need to be filled.