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浅埋多煤层开采过上覆煤柱强矿压致灾机理研究

Study on disaster-causing mechanism of strong mine pressure in shallow buried multi coal seam mining over overlying coal pillar

  • 摘要: 随着陕北浅埋多煤层矿区开采深度不断增加,下部工作面回采过上覆煤柱时,易诱发强矿压动力灾害,严重威胁矿井安全生产。针对龙华煤矿302盘区工作面在出煤柱阶段发生的压架事故,以该盘区30208工作面为工程背景,综合采用理论分析与数值模拟的方法,研究了覆岩位移场、裂隙场、关键岩层应力演化规律及力链分布特征,明确了工作面过上覆煤柱覆岩运移特征,并在矿井现场实施了针对性的防治措施,通过矿压监测验证了防治成效。研究结果表明:上部关键层形成“三铰式”结构,上覆煤柱作为“转载体”向下传递应力。当工作面出上覆煤柱边缘时,上部关键层铰接结构失稳破坏,上覆垮落岩层回转下沉,导致煤柱内应力发生偏移,诱发下部关键层异常周期破断,二者释放的能量在短时间内汇集并迅速释放,最终导致强矿压灾害。

     

    Abstract: With the increasing mining depth of shallow buried multi-coal seam mines in Northern Shaanxi, strong mine pressure dynamic disaster is prone to occur when the lower working face is mined back overlying coal pillar.This imposes a potential serious threat to the safety production of the mine.In view of the problem that support crushing accident in the coal pillar exit stage of the working face of plate area 302 in Longhua Coal Mine, this study takes the working face 30208 in this plate area as the engineering background.In this study, with the combination of the theoretical analysis and numerical simulation methods, we firstly explored the overlying strata displacement field, fissure field, stress evolution law of key rock strata and the distribution characteristics of the force chain, and then clarified the characteristics of overlying strata migration over the overlying coal pillar in the working face.The control measures were carried out in the mine and the results were verified by mine pressure monitoring.The results show that the upper key layer forms a 'Tri-hinge' structure, with the overlying coal pillar acting as a 'Transfer load body' to transmit the load downwards.When the working face is out of the overlying coal pillar edge, the hinged structure of the upper key layer is damaged.The overlying caving rock strata rotary subsidence of overlying rock strata, and the internal stress of the overlying coal pillar is shifted.These induce the lower key layer to abnormal periodic breaking, and the energy of the two is instantly released to the quarry, resulting in a strong mine pressure disaster.

     

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