深井富水工作面“动—静”应力效应诱发冲击地压机理研究
Mechanism of rockburst induced by “dynamic-static” stress effect in water-rich working face of deep well
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摘要: 冲击地压的发生是一个多因素诱发的结果。以郓城煤矿1301工作面为工程背景,研究“动—静”应力效应诱发的(“动”指工作面回采时,上覆岩层运动对前方煤体施加超前支承压力及扰动;“静”指水仓突水后,煤层上方相当于开采一个解放层,突水区域上覆岩层部分应力向周边转移,使突水区域周边的静应力升高)新型冲击地压发生的机理,本文采用采用理论分析、现场监测、工程试验、数值模拟等方法研究了冲击地压发生的应力来源、突水造成的煤体岩性改变特征、工作面回采的动态影响等,得出以下结论:①突水打破了原岩应力平衡,使其周边煤体静应力升高,这是冲击地压发生的静应力来源。②煤体浸水30天,使煤体的强度大幅降低,使其在同等应力作用下增大了“蠕变”冲击发生的风险。③1301工作面回采,超前支承压力是发生冲击地压的动应力来源;超前支承压力与高静应力叠加,增大了应力的集中程度,再加上上覆岩层对高应力集中区的动态扰动,使冲击地压发生的风险进一步加大。该方法对于富水工作面的防冲评价具有重要的参考意义。Abstract: 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.