深孔预裂强制放顶断裂力学模型研究

Research on the fracture mechanics model of deep hole pre-splitting for forced caving

预裂强制放顶是一种保障煤矿安全生产的重要技术。为确定初采期间深孔预裂强制放顶的合理参数,根据基本顶岩层的结构特点,基于断裂力学理论,建立含斜裂隙的深孔预裂强制放顶断裂力学模型,推导基本顶初次破断距及支架阻力表达式,对模型参数进行了敏感性分析。分析结果表明:基本顶初次破断距随预裂裂隙倾角或垂深比的增大而减小,随支架阻力的增大而增大;裂隙倾角从10°增加到90°,基本顶初次破断距的最大减幅为83.16%;裂隙垂深比从0.1增加到0.9,基本顶初次破断距的最大减幅为65.84%;支架阻力从3 MN增加到18 MN,基本顶初次破断距的最大增幅为1.4倍;理论计算与现场实测对比,验证了该模型的合理性,研究结果可为坚硬顶板煤层深孔预裂强制放顶参数设计和施工提供指导。

The pre-splitting for forced caving is an important technology to ensure the safe production of coal mines.In response to determine the reasonable parameters of deep hole pre-splitting for forced caving during the initial mining period,based on the characteristics of rock strata of main roof and the theory of fracture mechanics,the mechanics model of forced roof caving of deep hole pre-splitting was presented,and the sensitivity of model parameters was analyzed.The expression of the initial weighting distance of the main roof and support working resistance was deduced.The results show that the initial weighting distance of the main roof decreases with the increase of inclination or vertical depth ratio of pre-crack,increase with increase of support working resistance.The inclination of pre-crack increased from 10°to 90°,the maximum damped initial weighting distance is 83.16%.The vertical depth ratio of pre・crack increased from 0.1 to 0.9,the maximum damped initial weighting distance is 65.84%.The support working resistance increased from 3MN to 18MN,the maximum amplified initial weighting distance is 1.4 times.The theoretical calculation is compared with the actual field measurement,which indicated the reliability of the model.The research results can provide guidance for the design and construction of deep hole pre-splitting,have important theoretical significance and engineering value.