特定地质条件沿空留巷应用技术及理论研究.pdf

特定地质条件沿空留巷应用技术及理论研究 重庆大学博士学位论文 学生姓名杨红运 指导教师曹树刚 教 授 专 业矿业工程 学科门类工 学 重庆大学资源及环境科学学院 二 O 一六年十月 万方数据 万方数据 Application Technology and Theory Research of Gob-side Entry Retaining under Specific Geology A Thesis ted to Chongqing University in Partial Fulfillment of the Requirement for the Degree’s Doctor of Engineering By Hongyun Yang Supervised by Prof. Shugang Cao Specialty Mining Engineering College of Resources and Environmental Science of Chongqing University, Chongqing, China. Oct, 2016 万方数据 万方数据 中文摘要 I 摘 要 沿空留巷为回采巷道最终利用目标，其留巷效果决定于巷道自身地质条件及 巷道前期围岩控制质量。 本文基于川煤集团回采巷道不同复杂的地质条件， 以现场 调研、理论分析、相似材料模拟、数值模拟为手段，建立了沿空留巷适应性分级系 统， 发现煤层倾角及顶板完整性对沿空留巷适应性影响最大， 进而研究了特定地质 条件下， 近水平近距离煤层群切顶成巷技术， 大倾角煤层沿空留巷关键技术及完整 性差的巷道软顶岩体破坏机理， 建立了沿空留巷顶板控制力学模型， 系统分析了沿 空留巷巷道前期围岩破坏特征及支护技术。论文主要内容及成果如下 1 建立沿空留巷适应性分级系统。以煤层倾角、煤层厚度、巷道埋深、直接 顶岩性、直接顶影响系数及顶板完整性等 6 个地质因素评价沿空留巷适应性，并 通过层次分析法得到了 6 个地质因素影响权重， 发现煤层倾角、 顶板完整性最高， 即对沿空留巷适应性影响最大。其次，根据统计的 145 条沿空留巷巷道信息及现 场经验， 确定了沿空留巷适应性 5 个等级地质因素取值范围及每个等级留巷方式， 并采用模糊综合评判方法对川煤集团矿井 143 条回采巷道进行了模糊等级匹配， 分级结果得到了相关专家及工程师的普遍认同。 2 提出切顶成巷垮落顶板“承载体结构”模型。以白皎煤矿近水平近距离煤 层群地质条件为背景，开展了 3 条回采巷道切顶成巷平面相似材料模拟实验，发 现切顶垮落后， 巷道周边煤岩体出现明显的卸压现象； 另外， 3 条回采巷道的留巷 过程表明，当存在一定切顶偏移角，切顶高度大于采高，且垮落顶板未破坏时，最 终形成“承载体结构”平衡模型，并对其进行受力分析，求解了巷道顶板平衡控制 力与切顶偏移角及切顶高度的函数关系。 3 提出大倾角煤层沿空留巷关键技术。 通过对大倾角煤层老顶垮落结构、 采空 区充填特征、垮落矸石动力效应及应力重分布分析后发现，相对于近水平缓倾斜煤 层，大倾角煤层沿空留巷过程更有利于巷道围岩稳定。然而，垮落矸石自然充填为 大倾角煤层沿空留巷方式，其关键技术是实现巷旁有效挡矸，新研发的挡矸装置及 注浆加固系统稳定性高，能很好抵抗垮落矸石冲击力及加固矸石与底板。 4 研究了巷道软顶岩体破坏机理及支护技术。现场调研了软顶沿空留巷顶板 破坏特征，发现受侧向压力卸压松动作用、低位岩层不均衡支护与不耦合支护的局 部拉伸剪切作用、反复加卸压作用、动力扰动作用的严重影响，工作面端部顶板岩 体大范围破坏，完整性及稳定性进一步恶化，并在沿空留巷滞后压力稳定区沿巷旁 充填体外侧剪切断裂；最后，建立了关于煤层倾角、巷道宽度、软顶厚度、锚杆安 装角等参数的锚杆极限拉力平衡方程，探讨了软顶支护对策。 万方数据 重庆大学博士学位论文 II 5 探讨了沿空留巷巷道前期松动圈断面特性。 通过 55 条回采巷道松动圈地质 雷达测试， 发现回采巷道松动圈皆属于大松动圈， 且顶板及高帮松动圈深度普遍大 于低帮松动圈深度。然后，结合 3DEC 数值模拟结果及现场松动圈测试值，确定了 回采巷道围岩松动圈断面范围，发现绝大多数巷道围岩松动圈断面呈椭圆形或者近 似椭圆形，长轴沿着或者接近倾斜方向，短轴沿着或接近垂直层面方向，呈不对称 分布；另外发现，巷道断面形状及巷道掘进方式对松动圈断面形状的影响可忽略。 6 探讨了松动圈围岩基本支护初始承载特性。通过 FLAC3D 数值模拟实验分 析得知，锚杆预紧力在锚固段岩体扩散范围小，主要扩散区间位于锚杆自由段。进 一步分析发现高力学性能的锚杆及钢带，在高预紧力作用下，大松动圈围岩基本支 护组合拱初始承载区厚度可为锚杆自由段长度；明确提出组合拱支护理论条件下， 锚杆长度选取规则。 关键词关键词沿空留巷适应性，切顶成巷，大倾角，软顶，大松动圈 万方数据 英文摘要 III ABSTRACT Gob-side entry retaining GER as the ultimate goal for gateway using, the retained effect depend on the geological conditions themselves and support quality of surrounding rock in the early stage. In this thesis, base on the different complex geological conditions of gateways in “Sichuan coal group” coalmines, and taking the field investigation, theoretical analysis, similar materials simulation and numerical simulation as the means, it uated the adaptation of GER, and found that the geological factors of dip angle and roof integrity had the most influence to GER adaptability. Then, under specific geology, the technology of cutting roof and retained gateway CRRG in flat seam and close distance coal seam group, the key technology for GER in steep coal seam, and the failure mechanism for poor integrity gateway roof were researched. Moreover, the mechanics models for roof control were established. Finally, the failure characteristics of surrounding rock and supporting technology of GER gateway were systematically analyzed in earlier stage. 1 Bult adaptation grading system for GER. Six geological factors, including coal seam dip angle, mining height, cover depth, thickness influence coefficient of immediate roof, lithology of immediate roof and roof integrity, were determined to uate the adaptation, and their weight were analysed using analytic hierarchy process, indicating that the coal seam dip angle and roof integrity were the most important factor to the adaptation of GER. Moreover, five adaptive grades were classified and gob side support strategy for entry of each grade was provided according to statistical ination of 145 gateways and field experience. Finally, fuzzy comprehensive uation was used to weight adaptive grade index for 143 gateways in “Sichuan coal group” coalmines, and the results were generally recognized by the relevant experts and engineers. 2 Proposed the “bearing structure“ model with caving roof for CRRG. Taking the geological conditions of flat seam and close distance coal seam group in Baijiao coalmine as the background, the thesis carried out similar material simulation experiment for 3 gateways CRRG. It found that gateway surrounding rock appeared obvious stress unload phenomenon after the cut roof caving; Moreover, when there was a certain cut line deviation angle to vertical plane, the cut height was greater than the mining height, and the caved roof did not broke, the retained process for 3 gateways showed that caved roof ed “bearing structure“ balance model. Then carried on the force analysis for the 万方数据 重庆大学博士学位论文 IV model and solved the function relation for gateway roof balance control force with cut height and cut line deviation angle. 3 Proposed the key technology for GER in steep coal seam. After the analysis for roof caved structure, filling characteristic, dynamic effect and roof stress redistribution characteristic, it showed that GER in steep coal seams had more advantages than that in flat and gently inclined coal seam. However, naturally filling as the only retained in steep coal seam, and the key technology was to effectively block waste rock on gateway side, and the invented of rock blocking device and grouting reinforcement can well against the waste rock impact force and reinforce the waste rock and soft floor. 4 Researched the soft roof failure mechanism and supporting for GER. After investigating the soft roof failure characteristics for GER in field, it found that the soft rock mass at the working face end will break with large area, and the integrity and stability will further deterioration by the actions of the lateral stress unloading loose, tensile, and shear stresses in the low layer caused by uneven support and no coupling support, repeatedly load and unload, and dynamic disturbances. Moreover, the roof rock mass failed in shear mode along the inside of man-made constructed wall in the stability zone of the retained gateway, and finally the equation of the bolt ultimate equilibrium tension force, a function of the seam dip angle, gateway width, soft roof thickness, and bolt installation angle, was established to discuss the support countermeasures for the soft roof. 5 Discussed the gateway broken zone cross section features for GER in early stage. Though the 55 gateways broken zone test in surrounding rock with GPR, it found that the broken zone had large range, and the broken widths in the roof and high side wall were relatively large compared to those in the low side wall. Then, Combined with the tested broken widths and plastic zones in the 3DEC model, each gateway EBZ cross-section scope was determined. It was found that the EBZ distribution shapes were basically elliptical. The long axis was along the seam inclination direction, the short axis was along the vertical direction of the rock layer, presenting asymmetric failure ation. Also, the elliptical shape had little relationship with the gateway cross-section shape and driving . 6 Discussed the initial load-bearing characteristics for surrounding rock broken zone after basic support. After FLAC3D numerical simulation analysis, it found that the pretension force had lower diffusion sphere in the anchored rock zone, and the main diffusion sphere was in the bolt free rock zone. Moreover, further analysis showed that 万方数据 英文摘要 V the initial bearing zone thickness of combined arch structure in larger broken zone can be expressed by the bolt free length, when using high mechanic property bolt and steel with high pretension force, and clearly put forward the bolt length selection rule for driving period basic support under the combined arch supporting theory. Key wordsAdaptation for gob-side entry retaining, cutting roof and retained gateway, steep coal seam, soft roof, large excavation broken zone 万方数据 重庆大学博士学位论文 VI 万方数据 目 录 VII 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 研究背景和意义研究背景和意义 ....................................................................................................................... 1 1.2 国内外研究现状国内外研究现状 ....................................................................................................................... 2 1.2.1 回采巷道分类研究 ............................................................................................................ 2 1.2.2 沿空留巷应用研究 ............................................................................................................ 6 1.2.3 巷道破坏形态研究 ............................................................................................................ 9 1.3 研究内容及技术路线研究内容及技术路线 ............................................................................................................. 10 2 工程地质概况工程地质概况 .................................................................................................................... 13 2.1 概述概述 ......................................................................................................................................... 13 2.2 含煤岩系含煤岩系 ................................................................................................................................. 13 2.2.1 川东北煤田 ...................................................................................................................... 14 2.2.2 川东华蓥山煤田 .............................................................................................................. 15 2.2.3 川南煤田 .......................................................................................................................... 15 2.2.4 攀枝花煤田 ...................................................................................................................... 16 2.3 地质条件分布地质条件分布 ......................................................................................................................... 16 2.4 小结小结 ......................................................................................................................................... 20 3 沿空留巷技术适应性分析沿空留巷技术适应性分析 ......................................................................................... 21 3.1 概述概述 ......................................................................................................................................... 21 3.2 沿空留巷适应性研究方法沿空留巷适应性研究方法 ..................................................................................................... 21 3.3 模糊综合评判数学模型模糊综合评判数学模型 ......................................................................................................... 22 3.4 模糊综合评判因素集及评价集模糊综合评判因素集及评价集 ............................................................................................. 24 3.4.1 因素集的确定原则 .......................................................................................................... 24 3.4.2 沿空留巷适应性因素集 .................................................................................................. 24 3.4.3 沿空留巷适应性评价集 .................................................................................................. 25 3.5 沿空留巷适应性分级因素权重沿空留巷适应性分级因素权重 ............................................................................................. 26 3.5.1 AHP 方法确定因素权重 .................................................................................................. 26 3.5.2 沿空留巷适应性因素权重结果 ...................................................................................... 27 3.6 沿空留巷实例因素集统计分析沿空留巷实例因素集统计分析 ............................................................................................. 28 3.7 沿空留巷适应性等级指标值及留巷方式沿空留巷适应性等级指标值及留巷方式 ............................................................................. 32 万方数据 重庆大学博士学位论文 VIII 3.7.1 沿空留巷方式及应用条件 .............................................................................................. 32 3.7.2 沿空留巷适应性分级指标值 .......................................................................................... 33 3.7.3 沿空留巷适应性等级留巷方式 ...................................................................................... 34 3.8 沿空留巷适应性评价实例沿空留巷适应性评价实例 ..................................................................................................... 35 3.8.1 因素隶属函数 .................................................................................................................. 35 3.8.2 适应性评价实例 .............................................................................................................. 36 3.9 小结小结 ......................................................................................................................................... 37 4 近水平近距离煤层群切顶成巷分析近水平近距离煤层群切顶成巷分析 .................................................................... 39 4.1 概述概述 ......................................................................................................................................... 39 4.2 工程地质条件及相似材料模型工程地质条件及相似材料模型 ............................................................................................. 39 4.2.1 工程地质条件 .................................................................................................................. 39 4.2.2 相似材料模型设计 .......................................................................................................... 41 4.2.3 巷道支护相似材料 .......................................................................................................... 44 4.2.4 压力盒标定 ...................................................................................................................... 46 4.3 模型加载测试及开挖过程模型加载测试及开挖过程 ..................................................................................................... 48 4.4 煤层顶板切顶成巷岩层应力及变形破坏演化特征煤层顶板切顶成巷岩层应力及变形破坏演化特征 ............................................................. 49 4.4.1 B4煤层切顶成巷岩层应力及变形破坏演化特征........................................................... 49 4.4.2 B3煤层切顶成巷岩层应力及变形演化特征 .................................................................. 52 4.4.3 B2煤层切顶成巷岩层应力及变形演化特征 .................................................................. 54 4.5 切顶成巷实施效果分析切顶成巷实施效果分析 ......................................................................................................... 55 4.6 切顶成巷顶板力学结构特性切顶成巷顶板力学结构特性 .....................................................