【作者】 韩昌良；

【导师】 张农；

【作者基本信息】 中国矿业大学 ， 采矿工程， 2013， 博士

【摘要】 沿空留巷是无煤柱连续开采、无煤柱煤与瓦斯共采以及煤层群连续卸压开采等技术的空间基础，是解决瓦斯与动力灾害、提高煤炭采出率、降低巷道掘进率的重要保障，也是实现煤炭科学开采的关键技术之一。但是沿空留巷位处采空区边缘，服务期间经受多次采动影响，围岩结构的稳定与巷道空间的维控都将受到严重的挑战。本文采取物理模拟、数值计算和理论分析等综合研究手段，从采空区侧向顶板的岩层运动特征入手，细致分析了沿空留巷的顶板来压机理，揭示了留巷围岩的应力演化和最终分布规律，在此基础上得到了通过侧向顶板超前预裂实现留巷围岩区域应力优化的思路，阐明了侧向块体的断裂稳定机制，从而形成了区域应力控制技术，并进一步提出了围岩结构稳定控制技术体系，主要结论如下：（1）开采过程中采空区顶板先后出现分次垮落和一次性垮落两种现象，在垮落岩层上部主离层空间的隔离之下顶板发生应力分流，并经过侧向楔形区的传递作用向留巷围岩施压；顶板下沉量由断裂前的挠曲下沉、断裂时的旋转下沉和断裂后的压缩下沉三部分组成，因而对侧向低位岩体的给定变形具有长期性；沿空留巷在顶板分次垮落时表现为多次来压和长期渐缓变形，在顶板一次性垮落时表现为强烈来压和短期剧烈变形。（2）采场围岩的采动应力在平面和空间上分别呈双T型分布和应力环分布，沿空留巷则位于峰值应力T型区和谷值应力T型区之间，留巷围岩在顶板长期运动下持续弱化，整体处于低值应力区，采取深锚支护可调动深部支承应力环区岩体的高承载性能、约束浅部低值应力环区岩体的变形。（3）超前预裂卸压能够加速老顶的破断运动并有效缓解留巷顶板的压力，卸压后侧向支承应力向浅部转移、应力峰值有小幅降低，留巷围岩变形得到明显改善；断裂块体短期分离后还会再次接触并形成岩拱结构，结构间的力学关系决定了顶板卸压程度，因而悬臂长度存在优化空间；提出了侧向顶板的卸压判据和悬臂长度的优化方法。（4）分析了留巷围岩稳定的影响因素：巷旁支撑体与顶底板共同形成“顶-墙-底”复合承载结构，该结构的系统刚度决定了承载效率；巷旁充填体的强度发展与顶板压力应实现动态协调；锚固盲区与等效跨度增大时不利巷道维护。（5）提出了沿空留巷T型区围岩分区治理的技术思路，形成了留巷围岩结构稳定控制技术体系：结构上包括侧向顶板预裂卸压技术、巷道跨高比与墙体宽高比优化技术；支护上包括“三高”锚固技术、“高跨双减”支护技术及深锚浅注支护技术；巷旁支撑上包括膏体混凝土充填技术、砌块式巷旁充填技术、钢筒支柱式充填技术及高水材料充填技术；留巷长度上包括全长沿空留巷技术和阶段性沿空留巷技术。结合凤凰山矿154307工作面10m厚坚硬石灰岩顶板、小青矿E1403工作面1.45m薄层直接顶以及中兴矿1205工作面10m以上厚层复合顶板三种条件下的沿空留巷案例给出了工程验证。更多还原

【Abstract】 Gob-side entry retaining supplies the essential space for pillarless-continuousmining, pillarless-simultaneous extraction of coal and gas, and continuousde-stressing mining of coal seams, which provides a pretty important safeguard fordecreasing dynamic disasters of methane, boosting coal recovery ratio, reducingroadway drivage ratio and is one of key technologies for performing scientific miningof coal. However, both surrounding rock structure stability and space maintaneanceare under threat due to the fact that position of gob-side entry retaining is near the gob,which will suffer mining activity for many times during its service period.Through physical simulation, numerical simulation and theoretic analysis, thisdissertation analyzes systematically roof weighting mechanism by investigating roofstrata movement characteristics of lateral roof beside gob. Besides, on the basis ofstress evolution and distribution of the surrounding rock of gob-side entry, an idea thatapplying lateral roof presplitting technology optimizes region stress of surroundingrock is proposed, which indicates fracture stability mechanism of lateral block.Ultimately, region stress control technology is formed and structure stability controltechnology system for surrounding rock of entry is presented, from which it can beconcluded as follows:(1) Roof of gob experiences orderly fractionated collapse and once collapse incoal mining effect, which indicates after insulation of separation space from fracturedroof strata. Roof stresses are under distributary and impose pressure on thesurrounding rock of entry by transmiting effect from lateral wedge area. Subsidencevalue of roof consistes of deflection subsidence before fracture, rotation subsidence infracture period, and compression subsidence after fracture, which means givendeformation to low location rock mass continues a long time. Roof of gob-side entrypresents multi-weighting property and long term gradual deformation characteristicduring fractionated collapse, while it presents fierce weighting and short term severedeformation.(2) Mining stress for surrounding rock of mining panel presents T-shapedistribution and stress-ring distribution in a plane and in the space respectively, whilegob-side entry is located between valley point and peak point of T-shaped area.Surrounding rock of gob-side entry will become weaker under the condition of longterm movement of roof, which makes entry in low stress area and deep bolting support can exert the bearing capacity of deep rock mass and restrict rock massdeformation of shallow low-stress area.(3) Presplitting de-stressing can accelerate fracture movement of main roof,which can release pressure from entry roof. On this basis, abutment pressure willmove towards shallow area and there is a small decrease of peak point of stress. Theimprovement of de-stressing to deformation of entry surrounding rock, from high tolow, is roof, filling wall, floor and rib. It is noticed that fractured blocks will form newrock arch structure by attaching other blocks. Mechanics relationship betweenstructures determines stress release degree, which means optimization space ofcantilevel length is objective. Therefore, a new optimization methodology ofcontilevel length, with stress release criteria for lateral roof, is proposed in thisdissertation.(4) Impact factors about surrounding rock stability of gob-side entry are analyzedand these show that system stiffiness of “roof-wall-floor”structure, which is formedby gob-side supporting wall, roof and floor of entry, determines the bearing efficiency.Strength development of filling wall should be in accord with roof pressuredynamically and roadway maintaneance is hard when blind area of bolting andequivalent span increase.(5) An idea that district control technology for surrounding rock of T-shape areaof gob-side entry is proposed, which forms structure stability control technologysystem for surrounding rock of entry. Firstly, there are presplitting de-stressingtechnology for lateral roof, optimization techonolgy for span-depth ratio of roadwayand width-height ratio of wall in structure aspect. Secondly, there are three heightbolting technology, height-span reducing technology, and deep-bolting andshallow-grouting technology in supporting aspect. Thirdly, there are plaste-concretefilling technology, masonry structures filling technology, steel cylinder prop fillingtechnology and high-water material filling technology in filling aspect. Ultimately,there are full-length and stage gob-side entry retaining technology in entry lengthaspect.Combining with gob-side entry retaining engineering cases which contains10mthick hard limestone roof of entry in154307mining panel of FenghuangshangCoalmine, superposition main roof with1.45m thin direct roof in E1403mining panelof Xiaoqing Coalmine, and over10m compound roof in1205mining panel ofZhongxing Coalmine, these above technologies are tested and verified in this dissertation.更多还原