Influence of the method of gate road protection on the operating efficiency of methane drainage boreholes

Abstract

Methods of numerical modelling have helped to carry out the research of coupled processes of rock deformation around a gate road with methane drainage boreholes and methane filtration in terms of applying different techniques of its protection. The following has been shown: without the use of protective structures, underworked drainage boreholes are broken and stop functioning. If the protective structures are used, the rock-bolting beam above the mined-out space becomes stable. Boreholes go beyond the zones of inelastic deformations and remain in their operating conditions even after their undermining by a stope. The yield of a methane-air mixture in two methane drainage boreholes increases that is confirmed by experimental data. The efficiency of roof degassing by boreholes when using the considered protective structures is 13-63%. The borehole position is of great importance for its operating efficiency. If the borehole is beyond the filtration area, methane yield is minimal. It is quite high within the zone of increased fissuring of host rocks. If the methane drainage borehole is near the zone of inelastic deformations, methane yield reaches its maximum, but reliability of borehole operation is not high. The borehole is broken within the zone of inelastic deformations.