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Freezing method for rock cross-cut coal uncovering I: Mechanical properties of a frozen coal seam for preventing outburst.
Scientific Reports ( IF 3.8 ) Pub Date : 2019-11-08 , DOI: 10.1038/s41598-019-52879-y Jiwei Yue 1 , Gaowei Yue 2 , Zhaofeng Wang 1 , Minmin Li 2 , Binbin Wang 2 , Fenghua An 1
Scientific Reports ( IF 3.8 ) Pub Date : 2019-11-08 , DOI: 10.1038/s41598-019-52879-y Jiwei Yue 1 , Gaowei Yue 2 , Zhaofeng Wang 1 , Minmin Li 2 , Binbin Wang 2 , Fenghua An 1
Affiliation
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A comprehensive technology is proposed to realize fast and safe rock cross-cut coal uncovering (RCCCU) based on artificial freezing engineering method. This comprehensive technology includes four steps, namely, drilling a borehole, wetting the coal body by water injection, gas drainage and freezing the coal seam by liquid nitrogen injection. In this paper, the compressive strength, tensile strength and shear strength of frozen coal specimens are tested to obtain the mechanical parameters of the specimen. Then, for RCCCU under freezing temperatures, the outburst prevention effects are calculated and quantitatively analysed with regard to three aspects, namely, the enhancement of coal the mechanical properties, the reduction in the coefficient of outburst hazard (COH) in the distressed zone and the reduction in the interfacial elastic energy ratio (IEER) between the coal seam and the roof/floor. The results show that a considerable improvement in the mechanical properties of frozen coal and that the coal mechanical parameters, such as the compressive strength and the tensile strength, increase linearly with decreasing temperature. The coefficient of outburst hazard in the distressed zone decreases rapidly and drops from above 0.8 to below 0.3. The interfacial elastic energy ratio is greatly reduced from dozens of times of that of the roof/floor before freezing to several times of that of the roof/floor after freezing, which effectively weakens the sudden change of the elastic energy at the coal-rock interface.
中文翻译：
岩石横切煤的冻结方法I：防止突出的冻结煤层的力学性能。
提出了一种综合技术，基于人工冻结工程方法，实现了快速，安全的岩石横切面采煤（RCCCU）。这项综合技术包括四个步骤，即钻孔，通过注水使煤体润湿，抽气和通过液氮注入使煤层冻结。本文对冻煤试样的抗压强度，抗拉强度和剪切强度进行了测试，得出了试样的力学参数。然后，针对冻结温度下的碾压混凝土，从三个方面，即提高煤的力学性能，对防喷效果进行了计算和定量分析。降低了遇险区的突出危险系数（COH），并降低了煤层与顶板/底板之间的界面弹性能比（IEER）。结果表明，冷冻煤的力学性能有了很大的提高，煤的力学参数，如抗压强度和抗拉强度，随着温度的降低呈线性增加。危险区域的突出危险系数迅速下降，从0.8以上降至0.3以下。界面弹性能比从冻结前顶板/地板的数十倍降低到冻结后顶板/地板的数十倍，从而有效地减弱了煤岩界面弹性能的突然变化。
更新日期：2019-11-08
中文翻译：
岩石横切煤的冻结方法I：防止突出的冻结煤层的力学性能。
提出了一种综合技术，基于人工冻结工程方法，实现了快速，安全的岩石横切面采煤（RCCCU）。这项综合技术包括四个步骤，即钻孔，通过注水使煤体润湿，抽气和通过液氮注入使煤层冻结。本文对冻煤试样的抗压强度，抗拉强度和剪切强度进行了测试，得出了试样的力学参数。然后，针对冻结温度下的碾压混凝土，从三个方面，即提高煤的力学性能，对防喷效果进行了计算和定量分析。降低了遇险区的突出危险系数（COH），并降低了煤层与顶板/底板之间的界面弹性能比（IEER）。结果表明，冷冻煤的力学性能有了很大的提高，煤的力学参数，如抗压强度和抗拉强度，随着温度的降低呈线性增加。危险区域的突出危险系数迅速下降，从0.8以上降至0.3以下。界面弹性能比从冻结前顶板/地板的数十倍降低到冻结后顶板/地板的数十倍，从而有效地减弱了煤岩界面弹性能的突然变化。
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