厚煤层工作面顶板破断与能量场动态演化规律

    Roof breaking and dynamic evolution of energy field in thick coal seam working face

    • 摘要: 为了解决深井厚煤层工作面基本顶断裂时易使工作面前方支承压力显著增高和能量积聚的问题,以某矿5301综放工作面为工程背景,通过现场微震和工作面前方支承压力监测,并结合三维数值模拟,获得工作面推进过程中顶板破断、超前支承压力与能量场的演化规律,揭示工作面基本顶超前破断对能量场动态演化的影响。研究结果表明:基本顶断裂时,破断岩梁回转运动致使断裂线与工作面煤壁之间煤体破坏,导致工作面前方18 m范围内煤体能量释放,弹性能密度由55 kJ降低至28.5 kJ;随着基本顶与覆岩离层量增大,基本顶对上部岩层的支承点前移至断裂线以外位置,支承应力峰值前移至煤壁前方20~25 m左右,相应的断裂线以外煤体(煤壁前方22~90 m)可释放弹性应变能积聚(能量总增加量为176.2 kJ),能量峰值由80.15 kJ增大至136 kJ,能量集中系数达到2.94。

       

      Abstract: In order to solve the problems of significant increase of bearing pressure and energy accumulation in front of the working face when the basic roof of the working face in deep and thick coal seam is broken, this paper takes 5301 fully mechanized top coal caving face of a mine as the engineering background, the evolution law of roof breaking, advance abutment pressure and energy field in the process of working face advancing was obtained through field micro-seismic monitoring and abutment pressure in front of working face, combined with three-dimensional numerical simulation, and the influence of advance breaking of basic roof on dynamic evolution of energy field was revealed. Research results show that when the basic roof is fractured, the rotating movement of the broken rock beam causes the coal body to be destroyed between the fracture line and the coal wall of the working face, resulting in the energy release of the coal body within 18 m in front of the working face, and the elastic energy density decreases from 55 kJ to 28.5 kJ. With the increase of the separation amount between the basic roof and overburden, the supporting point of the basic roof to the upper rock stratum moves forward to the position beyond the fault line, and the peak of the supporting stress moves forward to about 20-25 m in front of the coal wall, and the corresponding coal outside the fault line (22-90 m in front of the coal wall) can release the accumulation of elastic strain energy (the total increase of energy is 176.2 kJ). The energy peak increased from 80.15 kJ to 136 kJ, and the energy concentration coefficient reached 2.94.

       

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