厚层放顶煤小煤柱沿空巷道采动影响段围岩变形机理与强化控制技术研究.pdf

国家自然科学基金资助项目（51374197，51474207） 国家重点基础研究发展计划（973 计划）资助项目（2015CB251603） 江苏省高校优势学科建设工程资助项目 煤炭资源与安全开采国家重点实验室开放研究基金项目（SKLCRSM12X06） 博士学位论文 厚层放顶煤小煤柱沿空巷道采动影响段 围岩变形机理与强化控制技术研究 Deation Mechanisms and Strengthen Technology for the Gob-side Roadway Surrounding Rock under Mining Influence in Top Coal Caving Face with Thick Layer 作 者张 蓓 导 师曹胜根 教授 中国矿业大学 二〇一五年六月 中图分类号 TD353 学校代码 10290 UDC 622 密 级 公开 中国矿业大学 博士学位论文 厚层放顶煤小煤柱沿空巷道采动影响段 围岩变形机理与强化控制技术研究 Deation Mechanisms and Strengthen Technology for the Gob-side Roadway Surrounding Rock under Mining Influence in Top Coal Caving Face with Thick Layer 作 者 张 蓓 导 师 曹胜根 教授 申请学位 工学博士 培养单位 矿业工程学院 学科专业 采矿工程 研究方向 矿山压力与岩层控制 答辩委员会主席 窦林名 评 阅 人 二〇一五年六月 学位论文使用授权声明学位论文使用授权声明 本人完全了解中国矿业大学有关保留、使用学位论文的规定，同意本人所撰 写的学位论文的使用授权按照学校的管理规定处理 作为申请学位的条件之一， 学位论文著作权拥有者须授权所在学校拥有学位 论文的部分使用权，即①学校档案馆和图书馆有权保留学位论文的纸质版和电 子版，可以使用影印、缩印或扫描等复制手段保存和汇编学位论文；②为教学和 科研目的，学校档案馆和图书馆可以将公开的学位论文作为资料在档案馆、图书 馆等场所或在校园网上供校内师生阅读、浏览。另外，根据有关法规，同意中国 国家图书馆保存研究生学位论文。 （保密的学位论文在解密后适用本授权书） 。 作者签名 导师签名 年 月 日 年 月 日 论文审阅认定书论文审阅认定书 研究生 张蓓 在规定的学习年限内， 按照研究生培养方案的要 求，完成了研究生课程的学习，成绩合格；在我的指导下完成本学位 论文，经审阅，论文中的观点、数据、表述和结构为我所认同，论文 撰写格式符合学校的相关规定， 同意将本论文作为学位申请论文送专 家评审。 导师签字 年 月 日 致 谢 致 谢 光阴如箭，岁月如梭，转眼间三年博士研究生生涯就要结束。在刚开始确定 读博的那一刻还在想，三年很漫长，怎奈，还没有享受够与老师、师兄弟们一起 学习奋斗的日子，另一扇窗早已打开，指引我去往新的方向。 掩卷而思，三年来在课题组，经历的点点滴滴，还没有走就时刻倍感怀念。 导师曹胜根教授在我研究生期间对我的教导以及熏陶， 助我树立了正确的人生价 值观，从曹胜根教授身上我学到了与人沟通的技巧以及做事的认真负责，在此， 对曹胜根教授表示最真挚的感谢。导师渊博的知识、与人为善的作风，给我留下 了深刻的印象。对我在生活上无微不至的关怀以及学习上孜孜不倦的指导，令我 感激不尽。论文从选题、思路以及具体写作，导师都花费大量心血指导我如何很 好的完成，再三言谢。 在研究生学习和生活中，缪协兴教授、许兴亮副教授都给与了很大帮助和关 怀， 同时也对论文的选题、 写作提出了宝贵意见， 在此， 对他们表示深深的感谢。 感谢霍州煤电庞庞塔煤矿王爱龙矿长、 罗同瑞副矿长在博士研究生期间给予 的现场支持， 从他们身上我学到了采矿人应有的严谨的工作态度以及正派的生活 作风，让我对以后的路充满信心。 在论文写作中，课题组硕士田素川、赵光辉、马鹏等同学都给予了很大的帮 助与支持，在此对他们致以最真挚的谢意。 父母之恩，无以为报，谨以此文献给我最亲的人，向他们呈交一份博士研究 生学习的答卷，希望他们满意。是他们生活上和精神上的支持，让我没有后顾之 忧， 可以专心的完成我的博士学业。 随着年龄的增长也更加体会到了父母的不易， 小的时候，我们开心是父母最大的事；长大后，父母开心是我们最大的事。 最后感谢各位专家、教授在百忙之中评审本论文，由于作者水平有限，且时 间短暂，文中疏漏和不足在所难免，恳请您的批评指正。 I 摘摘 要要 小煤柱沿空掘巷是综放工作面实现连续生产、快速接替、提高煤炭资源采出 率的重要支撑技术，在我国矿井应用十分广泛。由于沿空掘巷位于采空区边缘， 服务期间经受上工作面老顶侧向破断结构和本工作面采动影响， 巷道围岩应力环 境恶化，围岩稳定性受到破坏，严重困扰着沿空掘巷技术的现场应用。 本文采用理论分析、数值计算和相似材料模拟相结合的研究方法，以采空区 老顶侧向破断特征为切入点， 研究了上工作面和本工作面回采过程中老顶两次破 断结构特征以及对沿空巷道围岩应力的扰动规律， 揭示了沿空巷道围岩变形破坏 机理，提出了通过控制小煤柱和底板变形的围岩强化控制技术。主要成果如下 （1）综放工作面一次采动时侧向老顶“三铰拱”结构在破断块体铰接点处 产生极大的水平推力，对侧向煤体应力扰动剧烈。本工作面煤柱上方、破断老顶 铰接区域及工作面内部等位置超前支承压力影响距离及应力集中系数等方面存 在差异，其中煤柱上方应力分布受侧向老顶两次破断结构影响，并且在不同煤柱 尺寸条件下其影响主导地位不同。 （2）揭示了本工作面老顶侧向破断形式与煤柱尺寸之间的关系小煤柱时 侧向老顶由“固支梁”破断变为“铰支梁”破断，破断岩块长度较大并在一定条件下 发生二次破断，得到随煤柱尺寸增加，巷道围岩变形由煤体强度主导向采动应力 主导转变的结论。 （3）根据对小煤柱受力特征和变形规律的研究，分析了小煤柱的变形失稳 机理。提出了煤柱内部变形中性面的概念，中性面可以作为锚杆锚固的基点，锚 杆支护可显著增大煤柱中性面极限承载区的宽度与承载能力，实现小煤柱的稳 定，形成了基于中性面的全塑性小煤柱强化控制技术。 （4）开展了在非对称垂直压力作用下沿空巷道底鼓机理研究，得到了硬软 层组合底板发生弯曲破断和错纵剪切抬升的判别公式，垂直压力作用下，上位硬 层的破断是底板变形的分界点 初期硬层弯曲主导底板鼓起， 限制下部软层变形， 后期硬层破断使软层失去束缚，软层的破碎滑移成为底板变形的主体。 （5）根据沿空巷道底板变形特点，通过锚杆预紧力将底板岩层组合在一起， 增加其抗弯强度的同时提高层间抵抗滑移剪切的能力，限制软弱岩层的滑移空 间，形成了整体滑移型底鼓限制技术。 上述研究成果应用于庞庞塔煤矿 704 工作面运输平巷进行的工业性试验， 取 得了成功。 该论文有图 137 幅，表 14 个，参考文献 153 篇。 关键词关键词沿空掘巷；老顶破断；应力扰动；煤柱失稳；围岩控制 II Abstract For top-coal caving working face, gob-side entrydriving is the important supporting technologies for mining and development replacement, continuous production, raising the recovery rate of coal resources. It is widely used in coal mine in our country. The gob-side entrydriving is on the verge of mined-out area. In this area the surrounding rock stress conditions is deteriorated and the stability of the surrounding rock is broken down due to the influence of the breakage structure of lateral upper roof and the mining of working face during service. There are great threats to the stability of surrounding rock of gob-side roadway, and it has became the most important technology of gob-side entrydriving in field application. Combined s of theoretical analysis, numerical simulation and physical simulation were employed in this study. Based on the breakthrough point of the lateral upper roof breaking the many times structure, the structure character of surrounding rock of the gob-side roadway in different conditions was studied, the deation mechanism of surrounding rock of the gob-side roadway was revealed. On these basis, the surrounding rock strengthening technology which is used to control the deation of small coal pillar and floor was proposed. The main results were concluded as follows 1 The structure of lateral upper roof produces an immense horizontal thrust by the fully mechanized caving faces results severe stress disturbance on the lateral coal mass. The influential distance and stress concentration factor of the advanced support pressure have discrepancy in the working face top coal pillar, the lateral structure of main roof breakage and the working face. The stress distribution on top coal pillar is influenced by the lateral structure of main roof breakage structure, and the leading role is different under different pillar condition. 2 The relationship between main roof breakage and pillar size is revealed When the pillar is in small size, the “three hinged arch“ structure of last face make the breakage structure of main roof transferring from clamped cantilever beam structure to the hinge beam structure. Rock fracture length is long and the secondary fracture occurs in some certain conditions. The clamped breakage also occurs in the next face and the movement range of the roof gradually near the coal pillar. 3The instability mechanism was analyzed based on the study of the mechanics characteristic and deation law of the small pillar. The deation neutral surface III is proposed and it can serve as the anchor rod anchor points. The anchor bolt support can increase the wide and load capacity of the ultimate bearing area, realizing the stabilization of the small pillar. Thus the full-plasticity small pillar strengthen control technology is developed. 4 The gob-side entry mechanism of floor heave under dissymmetrical vertical stress is carried out, the discrimination ula of the bottom plate bending rupture and longitudinal shear fault uplift in thin hard stratum is obtained. Under the vertical stress, the breakage of the upper hard stratum is the cut-off point The hard stratum bending dominant the bottom up and limit the deation of the weak layer in preliminary stage. Then in later stage the hard stratum was broken, the weak layer slippage became the main part of bottom deation without restriction. 5 Based on the bottom deation character of the gob-side entry, by making the bolt pre-tightening force and bottom layers into one unit, it can increase the flexural strength and improve the ability of resisting interlayer sliding to limit the sliding space of the central soft rock. These research results has been successfully applied to the field test in typical geological conditions of Pangpangta coal mine. The essay has 137pictures, 14tables and 153 references. Keywords gob-side roadway; roof breaking; stress disturbance; instability of coal pillar; surrounding rock control IV Extended Abstract Gob-side entry is an advanced technology of roadway layout, and is a major breakthrough for coal mine safety mining. Based on the analysis of predecessors’ achievements and by comprehensive using of theoretical analysis, numerical simulation, physical test and the of industrial test, this dissertation began with overlying strata movement for gob-side entry retaining, established the mechanic model of the structural stability of overlying strata for gob-side entry, analyzed the stability of immediate roof and solid coal rib, and revealed the stability mechanism of surrounding rock for gob-side entry. The movement rule and the deation failure characteristics of surrounding rock for gob-side entry were gotten, and the large deations control technology of surrounding rock for gob-side entry was put forward. The main research content of this dissertation are as follows 1Based on the structural mechanics model, the ation and the its relationship with the internal and exterior stress field of the big and small structure of the extra-thick coal seam overburden was studied. The mechanical state of the coal in the boundary of goaf, the distributing rules of the supporting pressure, the stress analysis and deation and failure mechanism of the small coal pillars in the gob-side entry driving and the stability of the surrounding rocks of roadways were also invetigated. By setting up the structural mechanics model of the roadways in gob-side entry driving, the distributing situation of the stress field and the stress state from the boundary to the deep part was analyzed. At the same time, theoretical calculation within the internal stress field and the field test were carried out. By studying on the distributing rules of side supporting stress in the gob-side entry driving and the boundary and peak value of stress field, a elastic-plastic soften model was set up. Meanwhile, the optimal position, time and size of the gob-side entry driving was calculated. 2 Using the software FLAC3D, numerical simulations were carried out to study the evolvement law of stress and displacement of surrounding rocks under conditions of different pillar widths and mining depths. The changing law of surrounding rock stability with influencing factors is studied. In the process of roadway excavation, the displacement of surrounding rocks is in direct proportion to the stress relief with the rock strength being constant; and the displacement is in direct proportion to the rock V strength with the stress relief being constant. The peak stresses of roof and two sides of gob-side entries increase with the pillar width, and the same for the displacement of coal pillar. The reasonable width is in the range from 8m to 10m. The peak stresses of roof and solid side increase with the mining depth, and this is also true for the deation of surrounding rocks. 3There are three areas weak zone, transition zone, and high bearing zone. According to weakness degree of coal, restrain effect of weak zone to roof and floor of entry is low. When weak zone increases, equivalent span of roadway also increases, which, to some extent, deep bolting and shallow grouting can effectively control coal rib movement and reduce equivalent span of entry. 4Control principle of surrounding rock and roadway-in support technology forgob-side entry was put forward. On the basis of surrounding rock stress, surrounding rock deation and the distribution of plastic zone, the large deation mechanism of surrounding rocks for gob-side entry retaining was obtained. The key of surrounding rock control for gob-side entry retaining is to improve the integrity of roadway surrounding rock and their strength and adapt to the large deation of surrounding rock. Therefore, surrounding rock control requirements for gob-side entry retaining were put forward, and control technology of large deations of surrounding rock for gob-side entry retaining was ed. Through the previous research and field test, the following results were obtained. 1The large space produced by thick top coal caving mining faces results that the breaking and the caving of the immediate roof often cannot completely filling the mined-out area. The block hinged structure ed by a under hard rock breakage often has large angle rotation and touch floors and disturbance to intense stress of coal body is more drastic. The stress distribution and fracture partition show obvious corresponding relation. The influence of the lateral structure of main roof breakage on the abutment pressure distribution of the mining face was investigated. 2 The “three hinged arch“ structure of last face make the breakage structure of main roof transferring from clamped cantilever beam structure to the hinge beam structure. The results in a large impact on the working face and mine pressure appearance . The stability mechanism of the breaking rock in main roof through the establishment of the secondary fracture structure mechanics model after the breakage of the main roof in the face under certain conditions was investigated. It shows that VI the size of coal pillar has a notably effect on the structure. Early rotary secondary fracture occurs on the rock when it is small, articulated turning but will not break when it is medium. The clamped breakage also occurs in the next face and the movement range of the roof gradually near the coal pillar. 3The internal stress distribution and the rules of deation and failure was analyzed based on the mechanics structural features on small coal pillar in gob side entry after the secondary breakage of the main roof. The horizontal force produced by the last face delivers to the interface between the pillar and the immediate roof accelerates the deation of the coal pillar. The coal pillar will be broken and under peak load state after subjected to external dynamic load. The distribution of the vertical stress distribution is not symmetrical restricted by floor. The stress is highly concentrated at the bottom of the coal pillar near the tunnel. The main influencing factors to the stability of the coal pillar are found through the analysis of the bearing state and the size, the structure of the support strength, the relationship between the factors such as dynamic load and load time. This provides a fundamental theory for the control of large deation of small coal pillar. 4 The mechanism of coal pillar deation caused by bottom slip up was analyzed. The vertical stress distribution of coal inside the roadway on both sides of the air was presented in different characteristics. When the coal pillar was influenced by mining, the vertical deation of roof was restricted by floor extrusion. Accumulating deation was released to the horizontal free space, which stimulated the shear force that can resist the interlayer sliding and induced the bass drum. The given geological conditions of the bass drum incentives were analyzed. Horizontal shear force among layers was reduced by the increase of coal pillar strength, which has a remarkable effect on controlling the floor heave; Above thin hard stratum is the cut-off point of vertical stress and thin layer hard stratum can limit the deation of the weak layer. After it was broken, the weak layer was broken and slipped without restriction, and the floor heave risen dramatically. 5 The principle on the control of the stability of the rock that was surrounded by the goaf roadway which was severely influenced by the mining was put forward, and the control tech