Mechanism of rockburst induced by “dynamic-static” stress effect in water-rich working face of deep well

The occurrence of rockburst is a result of multi-factor induction. Taking coal face No. 1301 of Yuncheng Coal Mine as the engineering background, the mechanism of new rockburst induced by the "dynamic-static" stress effect is investigated ("dynamic" refers to that during mining of the working face, the movement of the overlying strata applies advanced support pressures and disturbance on the coal body in front of them; "static"refers to that after water inrush of the water storehouse, the part above the coal seam is equivalent to mining a liberated layer, and part of the stresses on the overlying strata transfers to the surrounding in the water inrush areas, and makes the static stress surrounding the water inrush areas increase). The stress source of rockburst, the lithological change characteristics of coal body caused by inrush water and the dynamic influence of mining face are studied by using theoretical analysis, field detection, engineering tests and numerical simulation. The following conclusions are drawn: (1) The inrush water breaks the stress balance of the original rock and causes high static stress around it, which is the static stress source of rockburst. (2) After 30 days of soaking, the strength of coal is greatly reduced, which increases the risk of rockburst under the same stress. (3) For mining of working face No. 1301, the advanced support pressure is the source of dynamic stress of rockburst. The superposition of advanced bearing pressure and high static stress increase the concentration of stress, and the dynamic disturbance of overlying strata to high-stress concentration areas further increases the risk of rockburst. The proposed method is of important reference significance for the anti-impact evaluation of water-rich working face.