【作者】 王伟；

【导师】 李宗翔；

【作者基本信息】 辽宁工程技术大学 ， 安全技术及工程， 2023， 博士

【摘要】 高瓦斯低渗透厚煤层开采时,采场瓦斯涌出量大,局部瓦斯积聚严重。在采、掘工作面进回风禁止通过冒落区及采空区政策以及碳达峰、碳中和背景下,深入研究采动影响下采场瓦斯运移规律,建立“以孔代巷”瓦斯治理体系对于防治瓦斯灾害、避免瓦斯外排至大气起着关键作用。文章以腾晖矿2-105工作面为背景,运用理论推导、数值计算、实验室试验及工程验证等综合研究方法从宏观角度探讨了开采厚煤层时上覆煤岩体裂隙、位移演化规律及采场应力重新分布机制。揭示了采空区上覆煤岩体下沉位移量随着工作面的推进而增加,随着高度的增加而减小,最大下沉位移量为3.5 m;采场应力重新分配,形成应力集中、卸压及应力恢复三个区域;应力集中区主要位于采空区支撑煤柱及工作面,应力值随着工作面的推进而增加,垂直方向随高度的增加而减小,应力集中系数最大值为2.55;卸压区上覆煤岩破坏严重,裂隙发育充分,形成瓦斯运移优势通道。基于SEM、CT扫描、单轴压缩试验等技术手段研究了应力影响下煤岩体裂隙特征。损伤煤岩体具有孔隙-裂隙双重介质,应力作用下煤岩裂隙发育呈现“H”、“Y”型分化。大量孤立孔隙结构为煤岩储存瓦斯提供了空间,瓦斯在煤岩体中存在扩散、渗流两种运动形式。通过煤岩体渗透率数值计算,揭示了损伤煤岩单元体的渗透率与损伤程度呈指数关系,计算出不同损伤煤、岩单元体渗透率分别相差7.71倍和445.03倍,岩体的渗透率对损伤敏感度高,同时得到了损伤煤岩单元体渗透率的取值范围。引入“等效裂隙”概念,建立了弹塑性煤岩体渗透模型,并进行了煤岩三轴渗透测试,得到采动过程中煤岩体渗透率随损伤程度指数增长的规律。结合应力场、渗流场、损伤破坏及扩散规律,建立了煤岩体弹性、塑形破坏流固耦合数学模型。借助COMSOL多物理场数值模拟软件对本煤层抽采钻孔、大直径尾抽钻孔、高位裂隙孔在多种边界条件下进行了数值模拟,通过弹性流固耦合模型揭示了SD渗透模型与自建模型抽采量基本一致,验证了推导的渗透率模型的普适性;建立煤层抽采影响因素体系,通过对弹性模型煤层渗透率、吸附变形、抽采负压、抽采半径等参数进行比较分析发现,煤层渗透率对瓦斯抽采效果敏感度高;基于塑形流固耦合模型揭示了大直径尾抽钻孔周围塑形破坏范围随应力增加而增加的发育规律,工作面塑形破坏后导致抽采钻孔失效和瓦斯涌出量增大的规律,并初步确定高位钻孔最佳参数配置,即抽采钻孔直径为150 mm时,顶板高位钻孔合理间隔不小于3.5 m。结合采空区上覆煤岩下沉、裂隙发育演化及采场瓦斯运动规律,建立了多物理场条件采场瓦斯运移控制方程;采用Fluent软件模拟了不同抽采机制、抽采参数条件下采空区瓦斯运移规律,确定了大直径尾抽钻孔能够改变采空区风流方向,防止采空瓦斯涌出,确定最佳抽采位置位于工作面后方5-15 m处。研究分析了顶板高位钻孔抽采机制,确定高位顶板钻孔最佳抽采位置为:水平距离回风巷30 m,高度范围位于距离顶板35-50m位置处。“以孔代巷”瓦斯治理体系在腾晖矿2-105工作面成功的进行了工程实践,为类似矿井进行瓦斯灾害防治,实现煤与瓦斯共采提供借鉴意义。本文有图113幅,表20个,参考文献200篇更多还原

【Abstract】 When mining high-gas and low-permeability coal seams,the amount of gas gushing out from the stope is large,and local gas accumulation is serious.It is difficult to meet the relevant requirements by relying on the existing wind exhaust and drainage technology,so it is very important to reveal the gas migration law in the stope under the influence of mining and establish the "replacing the tunnel with the hole" gas control system.Prevention and control of gas disasters and avoiding the discharge of gas into the atmosphere play a key role.Taking the 2-105 working face of Tenghui Mine as the background,using theoretical derivation,numerical simulation and other means to discuss the overlying coal and rock mass cracks,displacement evolution law and stope stress redistribution mechanism when mining thick coal seams from a macro perspective,the results show that,The subsidence displacement of the overlying coal and rock mass in the goaf increases with the advancement of the working face.In the vertical direction,due to the existence of the key layer,the subsidence displacement decreases with the increase of height,and the maximum subsidence displacement is 3.5m;The stress in the stope is redistributed to form three areas of stress concentration,pressure relief and stress recovery.In the pressure relief area,the overlying coal rock is severely damaged and the cracks are fully developed,forming a dominant channel for gas migration;the stress concentration area is mainly located in the The goaf supports the coal pillar and the working face,and its value increases with the advancement of the working face,and decreases with the increase of height along the vertical direction.The maximum value of the stress concentration factor is 2.55.Based on the uniaxial compression test,it is found that the fracture development of coal rocks presents "H" and "Y" type differentiation.With the help of SEM,CT scanning technology and other technical means,it is found that the damaged coal body has a dual medium of pores and fractures,revealing that the coal rock under the influence of stress The characteristics of cracks in the coal and rock mass,in which a large number of isolated pore structures in the coal and rock mass become the space for storing gas,and the gas moves in the coal and rock mass in two forms of diffusion and seepage;the coal and rock mass is simulated by using the Absolute Permeability Experiment Simulation of Avizo software Affected by stress,the damage degree has an exponential relationship with the permeability of coal and rock mass.The unit permeability of coal mass with different damage degrees differs by 7.71 times,and the unit permeability of different damaged rock mass differs by445.03 times.The sensitivity of rock mass to damage is high..Introducing the concept of "equivalent fracture",deduced the elastoplastic coal-rock seepage model,and carried out the coal-rock triaxial penetration test,revealing the law of exponential growth of the damaged coal-rock seepage evolution during the mining process.Combining the stress field,seepage field,damage law,and diffusion law,a fluid-solid coupling mathematical model of coal-rock mass elasticity and plastic failure was established.With the help of COMSOL multi-physics numerical simulation software,the coal seam drainage boreholes and large-diameter tail pumping boreholes were analyzed.Numerical simulations have been carried out on the drainage methods under various boundary conditions such as high-level fracture holes and high-level fracture holes.In this way,the universality of the derivation model was verified;through the analysis and comparison of parameters such as coal seam permeability,adsorption deformation,extraction negative pressure,and extraction radius of the elastic model,the influencing factors of coal seam drainage were revealed,among which the coal seam permeability had great influence on The gas drainage effect is highly sensitive;based on the plastic fluid-solid coupling model,the development law of the plastic failure area around the large-diameter tailing drilling hole increases with the increase of stress,and the plastic failure of the working face leads to failure of the drainage drilling and The law of the increase of gas emission and preliminarily determined the optimal parameter configuration of the high-level drilling,that is,the reasonable interval of the high-level drilling on the roof with a diameter of 150 mm is not less than 3.5m.Combined with the subsidence of the overlying coal and rock in the goaf,the development and evolution of fractures,and the movement of gas in the stope,a multi-physics field condition control equation for gas migration in the stope was established,and different drainage mechanisms and drainage parameters were simulated based on Fluent fluid numerical analysis.The law of gas migration in the goaf under the same conditions reveals that the large-diameter tail pumping borehole can well change the direction of the wind flow in the goaf and intercept the gushing of goaf gas,and the best drainage position is determined to be 5 behind the working face.The position of-15m;analyzed that the best extraction position of the high-level drilling on the roof is 30 m away from the return airway,and the height is at a position of 35-50 m from the roof,and carried out engineering practice on the 2-105 working face of Tenghui Mine for similar mines It provides a reference for the prevention and control of gas disasters and the realization of coal and gas co-mining.This dissertation has 113 pictures,20 tables,and 200 references更多还原