Energy criterion for the initiation of coal and gas outbursts in horizontal coal laneway

The energy criterion for the initiation of coal and gas outburst in horizontal coal laneway was studied within spherical coordinate system in this paper. Firstly, the stress distribution around coal heading was studied. Then four kinds of energy closely correlative with coal and gas outburst were studied which include: (a) the elastic potential released by coal, (b) the intrinsic gas energy which include expansion gas energy and energy released during gas desorbing, (c) crushing energy consumed during coal and gas outburst, which was obtained from impact crushing experiments of coal samples and screen results of outburst coal, (d) coal kinetic energy required during coal and gas outburst. Finally the energy criterion for the initiation of coal and gas outburst was suggested based on relationship analysis of the four kinds of energy. It is indicated that coal and gas outburst is governed by many factors such as in-situ stress, gas pressure, Protodyakonov coefficient, excavation footage, etc. The results are useful and can be used in practice for mine safety.