大倾角煤层综放开采顶煤破坏运移规律与支架稳定性分析

Migration laws of top coal failure and stability analysis of support on fully mechanized top coal caving mining in steeply dipping coal seam

对支架的稳定性控制是大倾角煤层长壁综放安全高效开采的关键。以长山子煤矿1123长壁综放工作面为工程背景,采用模拟实验、理论分析和现场监测相结合的方法,系统研究了非均衡受载与约束条件下顶煤的破坏运移规律及其对支架稳定性的影响。结果表明:在大倾角煤层长壁综放开采中,支架的稳定性随着顶煤法向载荷的增大、切向载荷和偏载程度的减小而增大。受煤层倾角影响,沿工作面倾向自下而上,顶煤的力学性质劣化程度、破碎区和塑性区范围等均逐渐增大,载荷传递能力逐渐减弱,支架工作阻力逐渐减小,支架沿走向和倾向的偏载程度逐渐增大。工作面倾向下部区域支架上方破碎顶煤受采空区矸石约束,运移空间有限,“顶煤-支架-底板”系统较稳定。工作面倾向中、上部区域支架上方破碎顶煤无矸石约束,破碎顶煤除了向支架尾梁方向移动外亦会沿侧向下滑,“顶煤-支架-底板”系统稳定性较差。且当工作面倾向中、上部区域破碎区顶煤移出后,该区域塑性区顶煤亦会破碎下滑,导致工作面倾向中上部区域的支承压力峰值区、顶煤塑性区和破碎区等均向深部延伸,顶煤沿工作面倾向的非对称破坏运移特征进一步增大,支架空载、低头和侧翻等现象频发,稳定性控制难度增大。

The key to safe and high efficiency mining of longwall fully mechanized top coal caving mining on steeply dipping coal seam lies in the stability control of supports.Based on the engineering background of No.1123 longwall fully mechanized caving working face in Changshanzi mine,this paper adopted comprehensive research methods of simulation experiment,theoretical analysis,and on-site monitoring to systematically analyze the failure and migration law of top coal and its influence on the stability of supports under the condition of unbalanced load and constraint.The results have shown that:in fully mechanized top coal caving longwall coal face in steeply inclined thick coal seam,the stability of the support increased with the increase of the normal load of the top coal,or with the decrease of the tangential load and the degree of eccentric load.Along the working face inclination from bottom to top,the deterioration degree of mechanical properties of the top coal,the range of crushing zone and plastic zone were gradually increased,the load transfer ability was gradually weakened,the working resistance of the support was gradually reduced,and the partial load degree along the strike and inclination of the support was gradually increased.The deterioration degree of top coal mechanical properties and the range of damaged zone and plastic zone were increased with the effect of coal seam angle.Meanwhile,the load carrying capacity was weakened,the support working resistance was reduced,and the degree of eccentric load along the strike and inclination of the support were gradually increased.In the lower area of the working face,the movement space of broken coal was limited and the“top coal-support-floor”system was relatively stable due to the constraint by the gangue in the gob.In the middle and upper areas,because there is no gangue constraint,the broken coal not only moved towards the tail beam of support but also slid sideways,and the stability of the“top coal-support-floor”system was poor.When the middle and upper areas of top coal inclination moved out,the top coal in plastic zone would also break and slide,which lead to the extension of abutment pressure peak zone,top coal plastic zone and broken zone in the middle and upper parts of working face to the deep.The characteristics of asymmetrical failure and migration of the top coal along the inclination of working face were further increased,the phenomenon of noload,bowing and rollover of the support frequently occurred,and the stability control was more difficult.