煤与瓦斯突出相似模拟试验及突出能量特征研究

发布时间：2018-07-21 10:19

【摘要】：煤与瓦斯突出是在井工开采煤矿生产过程中发生的一种极其复杂的动力现象。随着开采水平向深部延深,地应力和瓦斯压力增大、瓦斯含量增高,煤层透气性差,导致煤与瓦斯突出动力灾害日益严重和复杂,一些无煤与瓦斯突出危险性的矿井升级为突出矿井。为了有效预防和控制突出事故的发生,保障矿井安全生产,世界各主要产煤国家均投入了大量的人力、物力对煤与瓦斯突出进行了研究,以便为突出事故的预测和控制提供理论和技术依据。目前对于突出发生的机理以及突出过程中煤岩体破坏与发展机制的认识还停留在假说阶段,只能对突出过程中及突出发生后的一些现象进行解释,还没能形成一套完整的理论体系。由于煤与瓦斯突出事故的破坏性、突发性和特殊性,这就使准确监测并获取事故发生过程中的一系列参数不可能实现,也阻碍了科研工作的进一步发展。本文利用自主研发的大尺寸煤与瓦斯突出相似模拟装置对煤与瓦斯突出模拟试验进行了系统研究,对突出过程的各项物理参数进行测试;通过FLAC3D数值模拟软件模拟了大淑村矿煤样的突出试验过程中顶板应力变化规律,并通过煤与瓦斯突出的煤体损伤演化模型对突出过程中的煤;通过FLAC3D数值模拟软件,研究了工作面煤体采动应力的时空演化规律,并据此分析应力对突出的影响;通过开展煤体吸附瓦斯应变测试试验研究了孔隙气体对煤体的蚀损破坏作用,并据此分析瓦斯对突出的影响;最后通过所得到的结论对真实突出案例进行分析。本文取得了以下主要成果:(1)总结了国内外目前存在的各类突出模拟装置及突出模拟试验的优缺点,并此基础上,研发出一套“大尺寸煤与瓦斯突出模拟试验装置”。所研制的“大尺寸煤与瓦斯突出模拟试验装置”可以装填1t重的煤岩模型,注入100L左右的压力气体,能够较大程度真实地模拟在井下发生的突出现象。试验可以模拟不同成型压力、不同载荷大小、不同应力分布规律、不同瓦斯压力、不同顶底板岩层结构条件下的突出情况。(2)通过自主研发的大尺寸煤与瓦斯突出相似模拟装置开展大淑村煤矿2#煤层及振兴二矿2#煤层煤样的煤与瓦斯突出相似模拟试验。试验结果显示:在吸附稳定瓦斯压力分别为0.3MPa与0.6MPa条件下,突出煤岩样重量分别为369.9Kg及373.6Kg,最远抛射距离分别为41.4m及49.5m。吸附瓦斯压力越高,抛射距离越远,突出煤岩样中,纯煤样占的比重越大,煤样粉碎程度越高,验证了突出过程中吸附瓦斯主要对煤体进行粉碎作用的结论。突出发生后,突出煤样以突出口圆心所在直线为对称轴呈轴对称的扇形分布。在两次试验中,突出煤岩样以突出粉煤为边界,分别存在4个和6个扇形,扇形之间分布着垮落的顶板岩样。可以认为,在第一次和第二次试验过程中,分别存在4次和6次瓦斯粉碎煤体的过程。(3)通过图像处理的方法,对突出过程中获得的视频资料进行处理,得到突出粉煤-瓦斯混合流的速度分布规律。粉煤-瓦斯混合流在出口处的喷射速度为54.55m/s,然后速度逐渐衰减,在距离突出口1~6m范围内的平均速度下降为21.43m/s。在突出口前方无障碍物的情况下,突出煤样的重量主要分布在距离突出口较近处和较远处,而在有障碍物情况下,突出煤样重量主要集中在障碍物附近。突出发生后,煤层顶板岩层发生沉降,距离突出口越近的岩层,沉降值越大,挨着突出口所在壁面的岩层沉降了17.2cm,距离突出口越远,岩层沉降越少。突出煤层的直接顶岩层发生弯曲变形,呈现明显的自然拱形状。(4)通过flac3d数值模拟软件,模拟了大淑村矿突出模拟试验过程中应力演化规律。结果表明:突出过程中,煤层顶板应力分布沿工作面走向和倾向发生应力转移,突出口两侧应力集中区范围和应力值增大,沿走向煤层顶板应力向煤层深部转移趋势。利用123131对突出过程中的煤层应变演化特征进行分析,并结合应力演化特征,对能量演化特征进行分析。结果表明:在突出发展的第Ⅰ阶段,共消耗了30.26kj的弹性潜能,775.65kj的瓦斯内能,煤体抛出功为594.815kj,煤体破碎功为211.095kj。从突出发展的第Ⅰ阶段至突出结束阶段,共消耗了15.1kj的弹性潜能,481kj的瓦斯内能,煤体抛出功为409.8517kj,煤体破碎功为86.24kj。(5)通过对大淑村矿172103工作面的采动应力进行数值模拟研究,得到断层对采动应力时空演化规律的影响。模拟结果表明:在工作面前方煤体无断层构造时,在距离工作面3~5m范围内,煤体所受应力达到最大值为25.5mpa,为原岩应力的1.7倍,并在距离工作面8m左右的位置降低到原岩应力大小。所以,在距离工作面8m范围内的煤体,应力发生了急剧的变化,在应力转移过程中,这部分煤体所受应力先逐渐升高,在载荷的作用下被压缩,随着工作面的推进,峰值应力继续向深部转移,这部分煤体所受应力降低,并向采空空间膨胀,在膨胀过程中,部分煤体会被破坏,并发育新的裂隙;在工作面前方煤体中有断层构造时,峰值应力最大为28.5mpa,应力集中系数为1.9,在工作面推进到距离断层200m以内后,工作面前方煤体的峰值应力最大值有先增大后减小的现象。(6)通过岩石力学和弹性力学的理论知识,分析了断层构造带附近煤与瓦斯突出多发的原因。断层构造对附近煤体的应力分布影响较大,构造断层使峰值应力增大了3mpa,应力集中系数也从1.7增大到1.9,并使工作面前方应力值整体升高,越是靠近断层处,越产生更多的应力值起伏。同时,断层也使其两侧的煤岩体都产生了不同程度的应力集中。在断层构造附近,地应力与构造应力叠加,增加了断层附近煤体的峰值应力。同时,断层附近,构造软煤的发育,煤的透气性差、抗拉及抗压强度低,容易与卸压区之间产生较高的瓦斯压力梯度,处于脆弱的稳定状态,在外界扰动下,容易发生煤与瓦斯突出。(7)通过开展煤体吸附瓦斯应变试验研究瓦斯对煤体的蚀损破坏机制。结果表明:比表面积越大,煤体的吸附能力越强,吸附膨胀变形越大,随着吸附瓦斯压力的升高,吸附膨胀变形越大;吸附性越强的气体对煤体的蚀损破坏作用越明显。孔隙气体对煤体的蚀损破坏作用主要是孔隙气体的存在,使煤岩体内部的微裂隙、裂隙表面产生膨胀能,导致煤体颗粒之间的作用力减弱,被破坏时需要的表面能减小,降低了煤体强度,导致煤在瓦斯拉应力作用下发生突出。(8)根据论文前部分的研究结论,对大淑村矿的突出案例进行分析。通过SEM(扫描电子显微镜)对大淑村矿2#煤层的孔隙结构进行分形维数分析、开展分级加载条件下的蠕变试验及工作面回风巷道变形规律的现场观测,均表明大淑村矿2#煤层具有较强的流变特性。当1772205运料巷掘进到靠近煤柱下方时,地应力、煤柱集中应力、构造应力和工作面超前应力在此区域叠加,相比于不存在煤柱的煤体,这部分煤体所受的应力要高很多,远远超过煤体的屈服强度,极大缩短了蠕变第Ⅱ阶段的时长,迅速进入第Ⅲ阶段,在外界扰动下,发生煤与瓦斯突出。
[Abstract]:Coal and gas outburst is an extremely complicated dynamic phenomenon occurring during the production of coal mine. With the deep depth of mining level, the stress and gas pressure increase, the gas content is increased, the gas permeability is poor, and the coal and gas outburst dynamic disasters are becoming more and more serious and complicated, and some coal and gas outburst hazards are dangerous. In order to effectively prevent and control the occurrence of outburst accidents and ensure the safety of the mine production, all the world's major coal producing countries have invested a lot of manpower and material resources to study the coal and gas outburst so as to provide theoretical and technical basis for the prediction and control of the outburst accidents. The mechanism and the understanding of the mechanism of coal and rock mass destruction and development in the protruding process still remain in the hypothesis stage, and can only explain some phenomena during and after the protruding process, and have not formed a complete set of theoretical system. Because of the destructive, sudden and special characteristics of coal and gas outburst accidents, it can be accurately monitored and obtained. A series of parameters in the process of accident can not be realized, and the further development of scientific research is hindered. In this paper, the simulation test of coal and gas outburst is systematically studied by using the similar simulation device of large size coal and gas outburst, which is developed independently, and the physical parameters of the protruding process are tested and the numerical simulation of the FLAC3D is carried out through numerical simulation. The software simulated the roof stress change law during the outburst test process of the coal sample of the great Shu Village, and through the coal and gas outburst model of coal body damage evolution model to the coal in the protruding process; through the FLAC3D numerical simulation software, the time and space evolution law of the mining stress of the coal face is studied, and the effect of the stress on the outburst is analyzed and the effect of the stress on the outburst is analyzed. The test of coal body adsorption gas strain test studied the effect of pore gas on the erosion and damage of coal body, and then analyzed the effect of gas on the outburst. Finally, through the conclusions obtained, the real outstanding cases were analyzed. The following main achievements were obtained in this paper: (1) all kinds of prominent simulation devices and outburst existing at home and abroad are summarized. On the basis of the advantages and disadvantages of the simulation test, a set of "large size coal and gas outburst simulation test device" is developed. The "large size coal and gas outburst simulation test device" can fill in the 1t heavy coal and rock model, injecting the pressure gas around 100L, and can simulate the outburst happening in the underground to a large extent. The test can simulate different molding pressure, different load size, different stress distribution law, different gas pressure, different roof and floor rock structure conditions. (2) through the independent research and development of large size coal and gas outburst similar simulation device to carry out the 2# coal seam of the great Shu Village Coal Mine and the revitalization of the coal and gas process of the coal seam coal samples of the 2# coal seam in the revitalization of the mine The experimental results show that under the conditions of 0.3MPa and 0.6MPa, the weight of the outburst coal and rock is 369.9Kg and 373.6Kg, respectively, the higher the maximum ejection distance is 41.4m and 49.5m., the farther the ejection distance is, the farther the ejection distance is, the larger the proportion of the pure coal sample is, the more the coal sample is, the pulverizing process of the coal sample. The higher the degree, the conclusion that the adsorption gas is mainly comminuted to the coal body during the protruding process. After the outburst, the outburst coal sample is axisymmetric fan distribution with the straight line of the center of the outburst of the mouth. In the two test, the outburst of coal and rock samples to protruding the coal as the boundary, there are 4 and 6 sectors respectively, and the fans are distributed among the sectors. It can be considered that there are 4 and 6 Gas pulverized coal processes in the first and second tests. (3) through the image processing method, the video data obtained during the outburst process are processed to obtain the velocity distribution of the outburst coal gas mixture flow. The coal gas mixture flow is at the exit. The jet velocity is 54.55m/s, and then the velocity gradually attenuates. The average velocity in the range of 1~6m range from the outburst is reduced to 21.43m/s. at the front of the outburst. The weight of the outburst coal is mainly distributed in the near and far distance from the outburst, and the weight of the outburst coal is mainly concentrated in the barrier under the condition of obstacles. Near the object, after the outburst occurred, the roof strata of the coal seam subsiding, the more close to the outburst, the larger the settlement value, the rock layer next to the wall of the outburst is 17.2cm, the farther from the outburst, the less the rock stratum settlement. The direct top rock of the outburst coal seam is bending and changing, showing the obvious shape of the natural arch. (4) through the FLAC3D numerical value The simulation software simulates the stress evolution law in the process of the outburst simulation test of the great Shu Village mine. The results show that stress distribution of the stress distribution along the working surface along the working face occurs during the protruding process, and the stress concentration area and stress value of the two sides of the outburst are increased, and the trend along the roof stress of the coal seam to the depth of the coal seam. 1231 31 the evolution characteristics of coal seam strain during the outburst process are analyzed, and the characteristics of the evolution of the stress are analyzed. The results show that the elastic potential of 30.26kj is consumed in the first stage of the outstanding development, the internal energy of 775.65kj gas, the work of the coal body is 594.815kj, and the work of coal crushing is 211.095kj. from the outstanding development. From the first stage to the outgoing stage, the elastic potential of 15.1kj is consumed, the gas internal energy of the 481kj, the work of the coal body is 409.8517kj, the work of the coal body is 86.24kj. (5), through the numerical simulation of the mining stress of the 172103 working face of the great Shu Village mine, the influence of the fault on the time and space evolution of the mining stress is obtained. The simulation results show that: When the coal body is without fault structure in front of the working face, the maximum stress of coal body is 25.5Mpa, which is 1.7 times of the original rock stress in the range of distance working face 3~5m, and it is reduced to the size of the original rock stress at the distance of about 8m from the working face. Therefore, the stress changes sharply in the coal body within the range of 8m range from the working face, and the stress turns in the stress rotation. During the process, the stress of this part of the coal body is gradually increased and compressed under the action of load. With the advancing of the working face, the peak stress continues to move to the deep part. This part of the coal body is reduced to the stress and expands to the goaf space. In the process of expansion, some of the coal is destroyed and the new fissure is developed; in the coal body ahead of the working face, the coal body is in the front of the working face. When there is a fault structure, the maximum peak stress is 28.5mpa and the stress concentration coefficient is 1.9. The maximum peak stress of the coal body ahead of the working face increases first and then decreases after the working face is pushed to the distance fault 200m. (6) through the theoretical knowledge of rock mechanics and elastic mechanics, the coal and gas outburst near the fault tectonic zone is analyzed. The fault structure has a great influence on the stress distribution of the nearby coal. The tectonic fault makes the peak stress increase 3Mpa, the stress concentration coefficient increases from 1.7 to 1.9, and the stress value in front of the work is increased as a whole, the more the stress is near the fault, the more the stress value rises. At the same time, the fault also causes the coal and rock mass on both sides of the work. In the vicinity of the fault structure, the stress and the tectonic stress are superimposed, and the peak stress of the coal is increased near the fault. At the same time, near the fault, the development of the soft coal, the poor permeability of coal, the low tensile strength and the low compressive strength, is easy to produce a higher gas pressure gradient between the pressure relief area and is in a fragile stable state. Under the external disturbance, coal and gas outburst easily occur. (7) the corrosion damage mechanism of gas to coal is studied by the test of coal adsorption gas strain. The results show that the greater the surface area, the stronger the adsorption capacity of the coal body, the larger the adsorption expansion deformation, the greater the adsorption expansion deformation, and the stronger the adsorption property. The effect of gas on the erosion and damage of coal body is more obvious. The main effect of pore gas on the coal body is the existence of pore gas, which causes the micro crack and the crack surface in the coal and rock mass to produce expansion energy, resulting in the weakening of the force between the coal particles, the decrease of the surface energy needed when the coal body is destroyed, the coal strength and the coal in the tile. Under the action of SLA stress. (8) according to the conclusion of the previous part of the paper, the prominent case of Dadu village is analyzed. Through the SEM (scanning electron microscope), the fractal dimension of the pore structure of the 2# coal seam in the Dadu village mine is analyzed, and the creep test under the condition of graded loading and the scene of the deformation law of the air return roadway in the working face are carried out. The observation shows that the 2# coal seam in the great Shu Cun mine has strong rheological characteristics. When the 1772205 transportation lane is heading to the bottom of the coal pillar, the stress, the concentrated stress of the coal pillar and the superposition of the tectonic stress and the overstress in the working face are superimposed in this area. Compared to the coal body without coal pillar, the stress of this part of the coal body is much higher than that of the coal body. The intensity of the service greatly shortened the time of creep stage II and quickly entered the stage III, and coal and gas outburst occurred under external disturbance.
【学位授予单位】：中国矿业大学(北京)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TD713

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