【作者】 赵亮；

【导师】 赵耀江； 董红军；

【作者基本信息】 太原理工大学 ， 安全工程（专业学位）， 2020， 硕士

【摘要】 我国煤层普遍瓦斯含量高、渗透率低,存在瓦斯突出隐患的矿井、高瓦斯矿井较多,瓦斯治理已经成为我国煤矿安全管理工作的主要任务之一。同时,瓦斯作为煤矿开采的伴生产物具有较高的利用价值,在有效治理瓦斯和防治突出的基础上,能否高效抽采瓦斯已经成为煤矿安全生产研究重点。在煤与瓦斯突出防治方面,已经有专家提出低温冻结技术,同时低温致裂作用可增加煤层渗透率,提高瓦斯抽采效率,二者具有共同的技术手段。为了将这些技术手段更好地运用到煤矿,很有必要对低温处理中原煤声发射特性进行研究,分析低温状态下煤样结构演化规律,同时结合实际,深入研究低温处理后原煤力学渗流及声发射特性具有重要意义。为此,本论文采用理论分析和实验研究的手段,进行了原煤在低温处理过程中的声发射实验及低温处理后煤样的力学渗流及声发射特性实验,研究内容与主要成果如下:⑴低温处理声发射试验:(1)在低温处理过程中,煤样产生明显的声发射信号,直观表明了低温对煤样内部结构的破坏作用;冷处理温度越低对煤样内部结构破坏愈严重;相同冷处理温度下煤样产生的声发射信号在各个时期均有所不同,声发射信号大致可分三个阶段:密集爆发阶段、间断活跃阶段及平静阶段,均很好的反映了煤岩内部结构演化过程。⑵煤样单轴压缩试验:(1)原煤煤样峰值强度与损伤强度随冷处理温度地降低呈先升高后减小趋势;低温处理后煤样应变明显增加,但增加幅度随温度地降低不断缩短;损伤强度∕峰值强度的比值随着温度地降低不断增大。⑶低温处理原煤三轴压缩力学渗流及声发射试验:(1)煤样峰值强度随着冷处理温度地降低而逐渐减小,抵抗变形能力随温度降低不断减弱,在整体抗压强度降低的同时脆性增强。(2)随着冷处理温度不断降低,声发射峰值计数及声发射能量不断增大。(3)经低温冷处理过的煤样,瓦斯渗透率较常温相比明显增加;煤样由常温进入低温阶段,渗透率变化率最大M_k=0.0368;进入低温阶段,渗透率变化率随着温度地降低而变大;通过数据拟合可知,含瓦斯煤瓦斯渗透率与温度呈指数关系,随着冷冲击温度降低渗透率逐渐增大,且渗透率变化率呈先减小后增大趋势。更多还原

【Abstract】 The coal seams in China are generally high in gas content and low in permeability,and there are many mines with potential gas outburst and high gas mines.Gas control has become one of the main tasks of coal mine safety control in China.At the same time,gas as a companion product of coal mining has a high use value.On the basis of effective control of gas and prevention and control of outburst,whether gas can be efficiently extracted has become the focus of coal mine safety production research.In the aspect of prevention and control of coal and gas outburst,some experts have put forward the technology of low temperature freezing.At the same time,the effect of low temperature cracking of liquid nitrogen can increase the permeability of coal seam and improve the efficiency of gas extraction,both of which have the same technical means.In order to apply these technical means to coal mines,it is necessary to study the mechanical and acoustic emission characteristics of raw coal after low temperature.At the same time,combined with the actual situation,it is of great significance to study the seepage and acoustic emission characteristics of raw coal after low temperature treatment under the thermal mechanical coupling.In this paper,theoretical analysis and experimental research are used to systematically study the evolution of the internal structure of raw coal in the process of low-temperature treatment and the mechanical seepage and acoustic emission characteristics of coal samples after low-temperature treatment.The research contents and main results are as follows:(1)Acoustic emission test of low-temperature cold treatment:In the process of low-temperature treatment,the coal sample produces obvious acoustic emission signal,which intuitively shows the destructive effect of low-temperature on the internal structure of the coal sample;the lower the cold treatment temperature is,the more serious the damage is;the acoustic emission signal of the coal sample under the same cold treatment temperature is different in each period,and the acoustic emission signal can be roughly divided into three stages Stage: intensiveoutbreak stage,intermittent active stage and calm stage.(2)Uniaxial compression test of coal sample:(1)the peak strength and damage strength of raw coal sample increase first and then decrease with the decrease of low-temperature treatment temperature;the strain of coal sample increases obviously after low-temperature treatment,but the increase amplitude decreases with the decrease of temperature;the ratio of damage strength / peak strength increases with the decrease of temperature.(3)Triaxial test of coal and rock under low temperature treatment by thermo mechanical coupling:(1)the peak strength of coal sample decreases gradually with the decrease of cold treatment temperature,the resistance to deformation decreases with the decrease of temperature,and the brittleness increases with the decrease of overall compressive strength.(2)With the decrease of cooling temperature,the AE peak count and AE energy increase.(3)The gas permeability of coal sample treated by cold shock at low temperature is obviously increased compared with that at normal temperature;the maximum permeability change rate of coal sample is MK = 0.0368 from normal temperature to low temperature;the permeability change rate increases with the decrease of temperature when it enters low temperature;through data fitting,it can be seen that the gas permeability of coal with gas has an exponential relationship with temperature,and the permeability increases with the decrease of cold shock temperature The permeability change rate decreases first and then increases.更多还原