【作者】 张春华；

【导师】 刘泽功；

【作者基本信息】 安徽理工大学 ， 安全技术及工程， 2010， 博士

【摘要】 石门揭穿突出煤层时的煤与瓦斯突出,是煤矿生产中的一种极为复杂的动力灾害,这种类型突出的强度和危害性在各类突出中往往是最大的。据统计,约有80%的重、特大煤与瓦斯突出事故发生在石门揭煤的过程中。众所周知,煤与瓦斯突出这一复杂的力学现象是在某些特殊因素的共同作用下发生的,这些因素包括地应力、瓦斯压力和煤的结构及强度等。有的学者从煤与瓦斯突出发生地点的相关地质资料的研究中,得出这样的结论,大多数石门揭煤突出的发生和其发生地点的地质构造有密切的关系(这一点和其他类型的突出是一致的)。因此,有关地质构造影响下,石门揭煤过程中的围岩力学特性和突出机理的研究具有重要意义。以岩石力学、地质构造力学、瓦斯赋存与流动理论及煤与瓦斯突出机理等理论为基础,总结出了各种地质构造在煤层中形成的破坏区的共同特征,描述了“构造包体”的概念。然后,选择逆断层构造在煤层中所形成的压扭、封闭性破坏区作为试验中的“构造包体”,构建了石门揭含“构造包体”突出煤层的突出模型,并探析了模型中“构造包体”的力学和聚能特性以及模型的煤与瓦斯突出机理。依据淮南矿区C13-1煤这一典型突出煤层的顶、底板岩性分布及物理力学参数,在实验室内构建了煤与瓦斯突出模拟试验台,进行了石门揭煤相似模拟试验。在相似模拟试验中,对表征石门揭煤巷道掘进过程中围岩的力学特性及揭开含“构造包体”突出煤层时的相关参数进行了采集,其中包括：围岩应力的变化、围岩的位移,“构造包体”及煤层内瓦斯压力的变化,“构造包体”周围围岩的温度变化。通过对试验数据的分析研究,得出以下结论：第一,揭煤巷道向“构造包体”推进的过程中,巷道迎头端面前方围岩的一定范围内存在明显的应力降低和应力升高现象。第二,在石门巷道向“构造包体”推进过程中的良好支护范围内,巷道上覆围岩各点垂向位移量的最大值仅为3mm(相当于现场12cm)；在“构造包体”周围围岩的位移量在突出前很小,突出时猛增,最小为10mm(相当于现场0.4m),最大值超过了50mm(相当于现场2.0m)；突出终止以后,在上覆载荷的作用下,突出空洞的体积有所缩小,为最大空洞体积的80%。第三,随着瓦斯气体的充入,“构造包体”温度升高的幅度和速率大于两侧煤层；当突出发生时,两侧煤体的瓦斯压力和温度的下降时间滞后于“构造包体”,两侧煤体的瓦斯压力和温度的下降幅度也小于“构造包体”。第四,突出发生时,突出颗粒具有分选现象,并出现了典型的突出空洞。结合相似模拟试验,利用固-气耦合软件RFPA2D-Flow建立了石门揭含“构造包体”突出煤层数值模型,从细观的角度再现了石门揭含“构造包体”突出煤层时围岩的应力场、声发射、瓦斯流场及瓦斯压力场的演化及煤与瓦斯突出现象,数值模拟结果与相似模拟结果是基本一致的。此外,改变地应力和煤体强度的大小,进行了多次模拟计算,发现了以下规律：第一,高地应力、高瓦斯条件下,如果支护不力,巷道变形严重,煤层煤体和“构造包体”内松散煤岩进一步破碎,极易产生自“构造包体”向周围煤层扩展的大型突出；第二,低地应力、高瓦斯条件下,突出强度相对减弱,突出一般被限制在“构造包体”控制范围以内；第三,若提高“构造包体”的强度,即使在高地应力和高瓦斯压力条件下,突出也不易发生,煤体以破裂为主最后列举了含“构造包体”煤层突出的实例,论证了“构造包体”对煤与瓦斯突出影响的客观性；并利用构建的“构造包体”突出模型,对突出进行了分析,认为：在石门揭含“构造包体”突出煤层过程中,高瓦斯含量和压力、高地应力和低煤体强度是突出的发生的关键因素。通过理论分析、相似试验和数值模拟分析得出石门揭含“构造包体”突出煤层时突出发生的原因是：“构造包体”影响区存在构造应力场,围岩的初始应力较高；随着石门揭煤巷道的推进,该区域围岩的应力具有进一步增加的趋势,围岩变形小,瓦斯压力较高,即便当石门揭煤工作面推进至“构造包体”附近时,附近围岩仍然保持着较高的地应力和瓦斯压力；当揭煤工作面突然打开“构造包体”时,突出瞬间发生,附近围岩的地应力和瓦斯压力迅速降低。可见,在石门巷道推进过程中,含“构造包体”突出煤层一直维持着较高的地应力和瓦斯压力是造成突出的重要原因。论文的研究成果对深入认识复杂地质构造影响下石门揭煤突出机理和突出灾害防治具有一定的理论指导和现实意义。更多还原

【Abstract】 Coal and gas outburst of coal seam uncovered by crosscut is an extremely complex dynamic disaster in the coal mining, its intensity is often biggest in all kinds of outbursts and its hazardness is extremely high. Statistics indicates that 80% of the serious coal and gas outbursts occur in coal uncovering by crosscut. Therefore, study of outburst mechanism of the gaseous coal (rock) uncovered by crosscut has vital practical significances for guaranteeing the safe and highly effective production in coal mine. It is known to all, coal and gas outburst is a complex mechanical problem that occurs under special conditions, for example, crustal stress, gas pressure, coal structure and strength, and so on. According to the statistical data, as other kinds of outbursts, the outburst occur in coal seam uncovered by crosscut has some relation with the tectonic zone. But up to present, very few people have studied the mechanical characteristics of the surrounding rock during coal seam unvovering and the outburst characteristics systematically.Bases on the theories of the rock mechanics, the geognosy, the gas storage and flowing, and coal and gas outburst mechanism, and so on, the author defines the concept of "tectonic mass" after summarizing the characters of the rupture zones due to some kinds of geological structures. Taking the rupture zone in coal seam created by the reversed fault structure as the model, the author proposes the outburst model for "tectonic mass" containing coal seam uncovered by crosscut, and carries on preliminary analysis of mechanical and energy binding characteristics of the model, then, analyzes the coal and the gas outburst mechanism of the model.According to the distribution of layers and the coal (rock) mechanical characteristic around of C13-1 coal seam in Huainan, the author sets up experiment apparatus system for coal and gas outburst in the laboratory and carries on the similar material experiment of coal seam uncovered by crosscut in the apparatus. It studies the mechanical characteristics of the surrounding rock and the outburst characteristics of the "tectonic mass" containing coal seam, including:crustal stress evolution, the distortion and displacement, the change of gas pressure and temperature in the "tectonic mass" and coal seam when gasification and outburst starting. The findings are as follows:Firstly, because of the friction force between the model material and the wall of the apparatus, the menstruated stress around the apparatus wall is evidently lower. Secondly, as the workface of crosscut advancing to the "tectonic mass", obvious stress concentration exits in the front surrounding rock. Thirdly, in the process of advancing distortion and displacement exit in the upper surrounding rock, the biggest displacement, for good support laneway is 3mm (12cm if in the mine field), but when outburst takes place, the displacement of the "tectonic mass" surrounding rock surpasses 50mm (2.0m if in the field). Fourthly, when inflating gas, the increasing range and velocity of the temperature of the "tectonic mass" are larger and faster than that of the coal seam. Fifthly, after the outburst, the volume of the outburst cavity becomes 20% smaller than before.Combined with the laboratory similar material simulation, the author founds corresponding numerical model with the rock breaking solid-gas coupling software RFPA2D-Flow. It analyzes the evolution process of the crustal stress field, the AE, the gas flow field and the gas pressure field of the surrounding rock during the coal seam uncovered by the crosscut, and reappears the outburst of the "tectonic mass" containing coal seam uncovered by crosscut from a microscopic view.The simulating results are in substance coincident with that of the similar material experiment. Bsides, through changing stress and coal strength, it founds some other rules as follows:fitstly, besides increasing deformation of the surrounding rock, the high crustal stress may break the tectonic material further, and is helpful in forming large-scale outburst; secondly, for low stress situation, outburst coal is often limited to the scope of the "tectonic mass", the outburst intensity reduces relatively; thirdly, on the condition of high crustal stress and gas pressure, enhancing the mechanical properties of the "tectonic mass", the outburst is not easy to occur, only exits some rupture.Finally, the author gives some field cases of coal and gas outburst in coalseams which contain "tectonic mass" to approve the objective existence of the influence from the "tectonic mass".The author also explains the reason of these gas disasters with the discussion of the experiment studies.Through the theoretical analysis, similar experimental and the numerical simulation analysis, it obtains the reason for the outburst in uncovered coal seam containing "tectonic mass":because of the structure stress field, the virgin stress is high in "tectonic mass" zone; With tunnel advancing, the stress of the surrouding rock furtherly increases, the formation distortion is small, the gas pressure is high. Even when the workface is near to the "tectonic mass" zone, they are still very high; When the caving workface opens the "tectonic mss" suddenly, the outburst occurs instantaneously, then, the crustal stress and the gas pressure rapidly reduce. Obviously, in the process of the tunnel advancing, the outbursting coal seam which contians the "tectonic mass" has been maintaining high crustal stress and bearing pressure are the reason for the outburst. The research has certain theoretical instruction and practical profit significance to furtherly understanding the mechanism of the outburst in coal seam affected by complex geological structure and outburst disaster prevention.更多还原