Starikov G. The coal/gas system instability prediction at mining in outburst inclined coal seams

The work is based on theoretical studies that had enabled to construct the physical model predicting stability of the coal/gas system from free energy curve shape with account for methane filling density and relief wave velocity providing disclosure of the coal pore system. It was first experimentally established using a true triaxial compression technique that high speed relief of the gas saturated coal transforms it from ultimate condition into a two-dimensional stress state, this transformation forming a generalized tension in both stresses and strains and altering physical and mechanical characteristics with transition from shear fracturing mode to layer-by-layer tearing due to partial disclosure of closed pores containing 70 to 75 % of the occluded methane. These results had allowed substantiating the outburst criteria for a gas bearing coal seam with direct account for fluids content, stress state, and strength of coal. The criterion of determination of gas and coal outburst origin location was created based on the free energy curve shape change for the coal/gas system while the criterion of gas dynamics phenomena type classification was developed based on damage rate of the gas bearing coal volume estimated using methane escape activation energy and methane desorption time. Scientific results of the present thesis were included into normative documents regulating precedence rules for the methods developed by the author.