基于便携式里氏硬度测试的煤冲击倾向性分级判别准则

Classification criteria for coal bursting liability based on portable Leeb hardness testing

  • 摘要: 判别煤的冲击倾向性是评估煤矿冲击地压危险程度的主要依据之一,考虑到现有判别煤冲击倾向性分级的流程相对复杂。为此,提出了一种基于便携式里氏硬度测试的煤冲击倾向性判别方法。对来自4个煤矿的20个煤样开展里氏硬度测试、纵波波速测试和单轴压缩试验,获取了煤里氏硬度与岩石力学参数之间的拟合关系式,并探究了不同里氏硬度煤样在受压破坏过程中的能量演化规律。定义了描述煤样破坏时能量释放速率的系数KPE,并分析了KPE与传统煤冲击倾向性指标的关联。基于里氏硬度与KPE之间的关联,构建了基于里氏硬度的煤冲击倾向性分级判别准则。为验证该准则的合理性,将其判别结果与国家标准及煤屑弹射质量比F的判别结果进行对比,并在鄂尔多斯盆地某强冲击地压矿井选择了2个工程应用场景进一步对该准则的工程应用效果进行检验。结果表明:煤里氏硬度与单轴抗压强度、弹性模量具有强相关性,而与纵波波速相关性较弱;里氏硬度越大,煤样的储能及释放能力越强。不同冲击倾向煤样的KPE差异显著,且与传统冲击倾向性指标相关性较好,表明KPE可用于煤冲击倾向性分级判别。煤样的KPE与里氏硬度呈幂函数正相关,表明随里氏硬度的增加,煤样的冲击倾向性显著变化。基于便携式里氏硬度测试的煤冲击倾向性分级判别准则与国家标准、煤屑弹射质量比F的判别结果具有较好的一致性,同时在2种工程应用场景下的应用效果良好,表明该方法具有一定的可行性和可靠性。

     

    Abstract: Determining the bursting liability of coal is one of the main basis for evaluating the bursting risk degree of coal burst mine. Considering the complexity of existing classification procedures for determining coal bursting liability, a new method based on portable Leeb hardness testing is proposed. Combined with the Leeb hardness test, longitudinal wave velocity test and uniaxial compression experiment on 20 specimens from four coal mines, a fitting relationship between coal Leeb hardness and rock mechanics parameters was established. The energy evolution law during the compression failure process of specimens with different Leeb hardness values were investigated. A coefficient KPE was defined to describe the energy release rate during the failure of specimens, and the correlation between KPE and traditional indicators of coal bursting liability was analyzed. Based on the relationship between Leeb hardness and KPE, a coal bursting liability classification criteria based on Leeb hardness was established. To validate the rationality of this criterion, its classification results were compared with those based on the national standards and the ejection mass ratio of coal cuttingsF. Two engineering application scenarios from a strong coal burst mine in the Ordos Basin were selected to further assess the criterion's effectiveness in practical applications. The results show that the Leeb hardness of coal demonstrates a strong correlation with uniaxial compressive strength and elastic modulus, whereas there is no significant correlation with longitudinal wave velocity. The larger the Leeb hardnessis, the stronger the energy storage and energy release of the specimens in uniaxial compression tests.The KPE values varied significantly among specimens with different bursting liabilities and showed strong correlation with traditional bursting liability indicators, indicating that KPE can be effectively used for coal bursting liability classification. The KPE of specimens was positively correlated with Leeb hardness in a power function relationship, suggesting that as Leeb hardness increases, the bursting liability of specimens changes markedly. The coal bursting liability classification criteria based on portable Leeb hardness testing shows good consistency with national standards and the ejection mass ratio of coal cuttingsF classification results, and performs well in two engineering application scenarios, indicating that the method has a certain degree of feasibility and reliability.

     

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