Study of the Mechanisms of Coal and Gas Outbursts Using a New Numerical Modeling Approach

During mining or roadway development, the distribution of stress and pore pressure in the coal face and rib around the new opening will change. These changes are usually dependent on the mining history and are related to the rate of roadway development, geometry of the opening, the pre-mining stress and reservoir conditions, the strength of the coal, the adjacent rock strata and major geological structures, and the permeability of the coal. Quasi-static yielding of coal is usually observed at regions of high stress concentration. However, under certain conditions, dynamic failure of coal in the form of an outburst can occur. The occurrence of coal and gas outbursts and the way they evolve will depend on a number of factors and processes. Under varied mining conditions, some of the factors and/or processes may play a more important role in outburst initiation than others. It can be misleading to attribute the cause of an outburst to a particular factor or process. This is partly because some of the processes are highly non-linear; outburst occurrence may depend on how these processes evolve and interact. The problem becomes more complex because natural heterogeneity of the coal and geological structures also play an important part in the outburst mechanisms.