Development law and mechanism of surface cracks caused by shallow coal seam mining

Abstract

In the paper, N1212 working face was taken as the research object, the law and mechanism of surface cracks in shallow coal seam mining were studied by means of field investigation, dynamic monitoring and numerical simulation. The results show that the development degree of surface cracks in shallow coal seam mining is high, mainly “step” cracks, and the in-plane cracks are distributed at parallel intervals with an interval distance of 8-15 m. The cracks have two kinds of activity characteristics: “opening-closing” and “only opening and disconnecting”; the stress evolution and failure in the overlying strata extend forward in the form of “arch”, and the overlying rock fissures and surface cracks are connected with each other; the advanced generation and activity characteristics of surface cracks are closely related to surface movement and deformation, surface “tension-compression” deformation transformation and slope slip. The research results can provide a theoretical basis for the prevention and control of ground collapse in coal mining areas.

Keywords

• shallow coal seam
• mining damage
• surface cracks
• development law
• formation mechanism