Measures to deal roof-shock during tunneling at deep and extra-thick coal

Coalfields in Northwest China are mostly thick or extra-thick coal seams with low strength. During the tunneling of deep full-coal roadway, “roof-shock” may appear to the surrounding coal rock due to distortion and fracture caused by mining, which results in such accidents as roof caving and collapse. This study, taking the ingate connecting roadway of Yili No.1 Coal Mine as an example, discusses the roof-shock phenomenon during excavation. Firstly, the inducing factors of roof-shock are obtained by field monitoring and coal rock burst proneness tests. Next, FLAC3D simulation is employed on the failure characteristics of roof-shock, and on the pressure relief schemes of layered excavation. The modeling results show that the roof-shock aggravates the stress concentration and the damage of surrounding rock in the ingate connecting roadway. Stress distribution can be improved by adopting the layered excavation of the roadway and taking pressure relief and vibration-adsorption support measures. Further, the study creatively puts forward a “four-step” scheme to prevent roof-shock in the deep full-coal roadway, and applies it in the field test of ingate connecting roadway in Yili No.1 Coal Mine. The field monitoring results show that the support measures can effectively control the roof-shock, and the “four-step” scheme is proved a way to solve this problem in deep, extra-thick, and full-coal roadways.