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冲击倾向性对受载破坏煤样电荷规律影响的试验研究

Experimental study on influence of burst tendency on damage charge law of coal sample under loading

  • 摘要: 为了用电荷感应方法预测煤体冲击倾向性,研究了煤样冲击倾向性、物理力学特征以及电荷信号规律,重点分析了不同冲击倾向性煤样破坏全程电荷信号分布特征以及冲击倾向性指标与电荷相关参量的量化关系。研究结果表明:随着冲击倾向性增强,煤样破坏形式逐渐由破碎型向共轭剪切型再向单剪型转变;煤样破裂电荷信号的产生与应力突变具有较好的一致性;强冲击倾向煤样电荷信号主要集中在应力峰前的强化损伤阶段,煤样发生失稳破坏电荷前兆信息比较明显;弱冲击倾向煤样电荷信号主要集中在强化损伤和峰后破坏阶段;无冲击倾向煤样电荷信号主要集中在应力峰后的破坏阶段,煤样发生失稳破坏电荷前兆信息不再明显;煤样冲击倾向性越强,应力峰后累积电荷量越少,但应力峰后电荷变化率w越大;冲击能量指数KE与应力峰后电荷变化率w具有幂递增函数关系,弹性能量指数WET与应力峰后电荷变化率w具有线性递增函数关系。因此可以通过电荷信号整体分布规律以及应力峰后电荷变化率的大小来初步判断煤体的冲击倾向程度。

     

    Abstract: In order to explore the influence of burst tendency of coal samples by charge induction method,the burst tendency,physical and mechanical characteristics and charge signal law of coal samples were studied by laboratory test.The distribution characteristics of whole process of coal samples damage and the quantitative relation between the impact tendency indexes and the charge related parameters were analyzed emphatically.The results showed that with the increase of impact tendency,the failure mode of coal samples gradually changes from fracture type to conjugated shearing type and then to single shearing type.The generation of charge signals of ruptured coal samples has good consistency with the stress mutation.The charge signals of coal samples with strong impact are mainly concentrated in the stage of enhanced damage before the stress peak,and the charge precursory information of the coal sample is unstable and the charge precursor information is obvious.The charge signals of coal samples with weak impact are mainly concentrated in the stage of enhanced damage and post peak failure.The weak impact propensity coal sample charge signal are mainly concentrated in the failure stage after the stress peak,and the charge precursory information is no longer obvious.The stronger the impact tendency of coal samples,the less accumulated charge after stress peak,but the greater the charge change rate w after stress peak.The impact energy index KE has a power increasing function relationship with the charge change rate after stress peak,and the elastic energy index WET has a linear increasing function relationship with the post-stress peak charge change rate.Therefore,the degree of impact tendency of the coal body can be preliminarily judged by the overall distribution law of the charge signal and the magnitude of the charge change rate after the stress peak.

     

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