红岩煤矿无煤柱开采采空区倾斜下方向煤层消突带范围研究(1).pdf

红岩煤矿无煤柱开采采空区倾斜下方向 煤层消突带范围研究 重庆大学硕士学位论文 （专业学位） 学生姓名楚 涛 指导教师王宏图 教 授 兼职导师覃世福 高 工 专业学位类别工程（矿业工程） 研究方向矿山开采技术及理论 答辩委员会主席唐其武 教授级高工 授位时间2019 年 6 月 万方数据 Study on the Range of Coal Seam Outburst in the Direction of the Goaf Under the Coal Seam in Hongyan Coal Mine A Thesis ted to Chongqing University in Partial Fulfillment of the Requirement for the Professional Degree By Chu Tao Supervised by Prof. Wang Hong-tu Pluralistic Supervised by Tan Shi-fu June , 2019 万方数据 重庆大学硕士学位论文 中文摘要 I 摘 要 为了研究无煤柱开采采空区倾斜下方向煤层消突范围，以红岩煤矿 6煤层无 煤柱开采为工程背景，按照煤体弹塑性损伤变形理论、矿山压力理论、煤层瓦斯 流-固耦合理论和岩石力学理论，采用现场取样测试、实验室物理相似模拟试验、 数值计算和现场考察相结合的研究方法，展开对红岩煤矿 6煤层倾斜工作面推过 后采空区倾向下部煤层集中应力变化规律、条带范围瓦斯赋存规律及条带消突范 围的研究，为确定下区段工作面风巷区域是否需要布置底板抽放巷进行条带预抽 提供技术依据。论文的主要研究内容及取得的主要研究成果如下 ①由岩石试件的物理力学试验，得到不同层位岩石试件的单轴抗压强度、弹 性模量、泊松比参数、抗拉强度、粘聚力和内摩擦角等力学特性参数，为物理相 似模拟试验和数值模拟计算提供基础的物理力学参数。 ②通过物理相似模拟试验研究，得到了下区段煤层应力分布规律和最大集中 应力峰值位置；研究表明上区段采空区形成后，直接顶发生垮落，煤岩层出现 明显裂隙并向上发展，一段时间过后，上部新产生的裂隙宽度越来越小；下区段 煤岩层出现不同程度的变形位移，靠近采空区的煤岩体变形较大，煤体产生了膨 胀变形，为沿空煤体的瓦斯解吸、扩散、运移提供了良好的条件；且由于受采动 影响，下区段煤层应力重新分布，沿倾向方向逐渐升高，然后慢慢下降并趋于稳 定，在距离采空区 20cm（对应现场 20m）位置附近出现最大集中应力峰值。 ③基于煤层瓦斯流动的多物理场耦合理论，进行采空区对倾斜下部煤体应力 应变及瓦斯压力影响的数值模拟计算分析，得到了沿空煤体倾向应力应变分布规 律、上区段工作面开采前后瓦斯压力变化规律和上区段工作面回采以后不同时间 瓦斯压力沿倾向的分布规律；研究表明随着上区段煤层的开采，下区段煤岩层 原来的平衡应力场被破坏，峰值应力沿煤层倾向下部传播，在距离采空区 17m 附 近出现最大集中应力峰值，与物理相似模拟试验得到的最大集中应力峰值位置相 近；且因采动影响，沿空煤体瓦斯赋存状态发生变化，煤体内吸附的瓦斯逐渐转 变为游离状态，靠近采空区位置的煤体渗透率最大，解吸的瓦斯逐步向采空区扩 散，沿空煤体瓦斯压力降低，消突范围随时间延长逐渐扩大；随采空区边界距离 增加，煤层残余瓦斯压力下降的速率越慢，当距离超过 25m 后，煤层残余瓦斯压 力达标所需的时间将大大延长。 ④红岩煤矿 6煤层上区段工作面回采前后，对下区段煤层研究范围内的瓦斯 压力、瓦斯含量进行了现场考察，得到了在上区段采空区形成一定时间范围内， 煤层瓦斯含量小于消突指标8m3/t的下区段条带消突范围和不同位置瓦斯压力下降 万方数据 重庆大学硕士学位论文 中文摘要 II 的幅度；现场实测表明，工作面回采过 595 天后，距离采空区 25m 以内的下区段 煤层残余瓦斯含量由 7.8m3/t 降到平均 2.69m3/t；煤层瓦斯压力也发生了不同程度 的下降，距离采空区 15m 的位置，瓦斯压力从 3.1MPa 下降到 1.4MPa，距离采空 区 25m 的位置，瓦斯压力从 2.8MPa 下降到 1.8MPa，均大于 0.74MPa；对观测数 据进行拟合分析发现，距离采空区 15m 处的钻孔瓦斯压力随时间的变化近似呈线 性变化，根据回归方程推测出在上区段工作面开采约 770 天后，距离采空区 15m 处的钻孔瓦斯压力将降到 0.74MPa 以下，而距离采空区边界 25m 处的瓦斯压力已 经基本保持稳定；采空区下部煤体的瓦斯排放是一个受时间影响较大的排放过程； 现场实测瓦斯压力变化规律结果与数值计算结果基本吻合。 关键词关键词无煤柱开采；消突范围；物理相似模拟；数值模拟计算；现场考察 万方数据 重庆大学硕士学位论文 英文摘要 III Abstract In order to study the outburst range of the coal seam under the inclined direction of the coal-free mining goaf, the coal-body blasting deation theory, mine pressure theory, coal seam gas flow-solid Based on the theory of coupling, laboratory physical similarity simulation test, numerical calculation and on-site investigation is carried out to develop the lower part of the goaf after the inclined working face of the 6 coal seam of Hongyan Coal Mine The study on the occurrence law of coal seam gas and the size of the outburst is to provide a basis for determining whether the wind tunnel area of the lower section needs to be additionally arranged for the strip drainage. The main research results are as follows ①From the physical and mechanical tests of rock specimens, the mechanical properties of uniaxial compressive strength, tensile strength, cohesion and internal friction angle of different layer rock specimens are obtained. ②After the upper section of the goaf is ed, the direct roof collapses, and the coal seams show obvious cracks and develop upwards. After a period of time, the newly created crack width becomes smaller and smaller until it closes. The coal seams in the lower section also have different degrees of displacement deation. The coal and rock mass near the goaf is strained, and the coal body may undergo expansion and deation, which provides good conditions for gas desorption and diffusion along the coal. And due to the influence of mining, the stress balance of the lower section coal seam is redistributed after failure, and the stress peak appears near the position of 20cm corresponding to the field 20m from the goaf. ③Strain and gas pressure of inclined coal body is carried out. The study shows that with the mining of the upper section of the coal seam, the original equilibrium stress field of the lower section of the coal seam is destroyed, the peak stress propagates to the lower part of the coal seam, and stress concentration occurs near 17 m from the goaf. Due to the influence of mining, the gas occurrence state along the empty coal body changes, the gas adsorbed in the coal body gradually changes to a free state, and the coal body near the goaf position has the highest permeability, which is 6.5e-17 m2, desorbed gas. Gradually spread to the goaf, the gas pressure along the empty coal body decreases, and the extent of the outburst gradually expands with time. The numerical results show that as the boundary distance of the goaf increases, the rate of residual gas 万方数据 重庆大学硕士学位论文 英文摘要 IV pressure drop in the coal seam is slower and nonlinear. When the distance exceeds 25 m, the time required for the residual gas pressure of the coal seam to reach the standard will be greatly extended. ④Before and after the mining of the upper section of the 6 coal seam in Hongyan Coal Mine, the gas pressure and gas content in the research area of the lower section coal seam were investigated on site. It is found that after 500 days of working face mining, the residual gas content of the lower section coal seam within 25m from the goaf is less than 8m3/t; the gas pressure has also decreased to different extents, 15m away from the goaf, gas pressure From 3.1 MPa to 1.5 MPa, the gas pressure dropped from 2.8 MPa to 1.9 MPa from the position of 25 m in the goaf, both greater than 0.74 MPa.The fitting analysis of the observation data shows that the gas pressure of the borehole at different distances from the goaf changes linearly with time. According to the regression equation, it is estimated that after about 770 days of mining in the upper section, 15m away from the gob. The gas pressure of the borehole will be reduced to below 0.74 MPa, and the gas pressure at the location 25 m from the boundary of the goaf has remained basically stable. The residual gas content and residual gas pressure in the corresponding area after 2-3 years of mining in the adjacent section were measured. The results show that the residual gas content is less than 8m3/t. This shows that the gas emission from the coal in the lower part of the goaf is a discharge process that is greatly affected by time. Key words Coalless Pillar Mining; Dissipation Range; Physical Similarity Simulation; Numerical Simulation; Site Investigation 万方数据 重庆大学硕士学位论文 目 录 V 目 录 中中文摘要文摘要 .......................................................................................................................................... I 英文摘要英文摘要 ....................................................................................................................................... III 1 绪绪 论论 ...................................................................................................................................... 1 1.1 选题背景选题背景 ................................................................................................................................... 1 1.2 研究目的及意义研究目的及意义 ....................................................................................................................... 1 1.3 国内外研究现状国内外研究现状 ....................................................................................................................... 3 1.3.1 沿空煤体卸压带研究现状 ................................................................................................ 3 1.3.2 沿空煤体瓦斯分布规律研究现状 .................................................................................... 3 1.3.3 沿空煤体应力与瓦斯流场的相互作用 ............................................................................. 4 1.4 研究内容及技术路线研究内容及技术路线 ............................................................................................................... 6 1.4.1 主要研究内容 .................................................................................................................... 6 1.4.2 技术路线 ............................................................................................................................ 7 2 煤层顶底板物理力学特性研究煤层顶底板物理力学特性研究 ................................................................................. 9 2.1 研究目的及现场取样研究目的及现场取样 ............................................................................................................... 9 2.1.1 研究目的 ............................................................................................................................ 9 2.1.2 试件现场取样 .................................................................................................................... 9 2.2 试件的单轴压缩试验试件的单轴压缩试验 ............................................................................................................... 9 2.2.1 单轴压缩试验过程 ............................................................................................................ 9 2.2.2 单轴压缩试验结果 .......................................................................................................... 11 2.3 试件的巴西劈裂试验试件的巴西劈裂试验 ............................................................................................................. 11 2.3.1 巴西劈裂试验过程 .......................................................................................................... 11 2.3.2 巴西劈裂试验结果 .......................................................................................................... 12 2.4 试件的压剪试验试件的压剪试验 ..................................................................................................................... 12 2.4.1 压剪试验过程 .................................................................................................................. 12 2.4.2 压剪试验结果与分析 ...................................................................................................... 13 2.5 本章小结本章小结 ................................................................................................................................. 15 3 采空区对沿空煤体应力应变影响的物理相似模拟试验采空区对沿空煤体应力应变影响的物理相似模拟试验.......................... 16 3.1 物理相似理论物理相似理论 ......................................................................................................................... 16 3.1.1 物理相似模拟的理论基础 .............................................................................................. 16 3.1.2 物理相似模拟的相似条件 .............................................................................................. 16 3.2 物理相似模拟试验装置及参数确定物理相似模拟试验装置及参数确定 ..................................................................................... 17 万方数据 重庆大学硕士学位论文 目 录 VI 3.2.1 物理相似模拟试验装置 .................................................................................................. 17 3.2.2 试验参数确定及试验过程 .............................................................................................. 18 3.3 物理相似模拟试验结果分析物理相似模拟试验结果分析 ................................................................................................. 20 3.3.1 采空区上覆岩层裂隙发育情况及垮落效果分析 .......................................................... 20 3.3.2 煤岩层变形位移规律及裂隙分布 .................................................................................. 20 3.3.3 采空区下区段煤层应力应变分析 .................................................................................. 22 3.4 本章小结本章小结 ................................................................................................................................. 24 4 采空区对沿空煤体消突范围影响的数值模拟采空区对沿空煤体消突范围影响的数值模拟 ............................................... 25 4.1 煤层瓦斯运移多场耦合模型煤层瓦斯运移多场耦合模型 ................................................................................................. 25 4.1.1 煤体孔隙率动态变化方程 ............................................................................................... 25 4.1.2 煤层瓦斯渗流场方程 ....................................................................................................... 25 4.1.3 煤岩体变形控制方程 ....................................................................................................... 25 4.2 沿空煤体瓦斯运移几何模型建立及多场耦合模型求解沿空煤体瓦斯运移几何模型建立及多场耦合模型求解 ..................................................... 26 4.2.1 几何模型建立 .................................................................................................................. 26 4.2.2 参数设定 .......................................................................................................................... 27 4.2.3 边界条件设定 .................................................................................................................. 27 4.2.4 模型求解 .......................................................................................................................... 27 4.3 沿空煤体倾向应力应变分布规律沿空煤体倾向应力应变分布规律 ......................................................................................... 28 4.4 沿空煤体倾向瓦斯压力变化规律沿空煤体倾向瓦斯压力变化规律 ......................................................................................... 29 4.5 沿空煤体不同时间瓦斯压力沿倾向的分布规律沿空煤体不同时间瓦斯压力沿倾向的分布规律 ................................................................. 31 4.6 本章小结本章小结 ................................................................................................................................. 32 5 采空区对沿空煤体消突范围影响的现场试验采空区对沿空煤体消突范围影响的现场试验 ............................................... 34 5.1 现场试验内容与试验方法现场试验内容与试验方法 ..................................................................................................... 34 5.1.1 研究地点及范围 .............................................................................................................. 34 5.1.2 研究区域瓦斯参数情况 .................................................................................................. 34 5.1.3 研究区域 3603-2 段工作面情况 ..................................................................................... 35 5.1.4 煤层瓦斯消突指标要求 .................................................................................................. 35 5.2 现场测试钻孔设计现场测试钻孔设计 ................................................................................................................. 35 5.2.1 现场考察点布置 ............................................................................................................... 35 5.2.2 封孔并安装压力表 ........................................................................................................... 37 5.2.3 压力表读数工作 .............................................................................................................. 38 5.3 现场试验结果与分析现场试验结果与分析 ............................................................................................................. 38 5.3.1 残余瓦斯压力测定结果与分析 ...................................................................................... 38 5.3.2 残余瓦斯含量测定结果与分析 ...................................................................................... 41 万方数据 重庆大学硕士学位论文 目 录 VII 5.3.3 预计煤层消突达标时间分析 .......................................................................................... 42 5.4 本章小结本章小结 .........................................................................