Rockburst mechanism in soft coal seam within deep coal mines

Abstract

A number of rockburst accidents occurring in soft coal seams have shown that the rockburst mechanism involved in soft coal seams is significantly different from that involved in hard coal seams. Therefore, the method used to evaluate rockburst in hard coal seams is not applicable to soft coal seams. This paper established an energy integral model for the rockburst-inducing area and a friction work calculation model for the plastic area. If the remaining energy after the coal seam is broken in the rockburst-inducing area is greater than the friction work required for the coal to burst out, then a rockburst accident will occur. Mechanisms of “quaking without bursting” and “quaking and bursting” are clarified for soft coal seams and corresponding control measures are proposed as the optimization of roadway layouts and use of “three strong systems” (strong de-stressing, strong supporting, and strong monitoring). Keywords: Soft coal seam, Rockburst, Plastic zone, Elastic strain energy, Friction work