采动覆岩结构的“关键层-松散层拱”理论及其应用研究.pdf

博士学位论文 采动覆岩结构的“关键层-松散层拱”理论 及其应用研究 Structure of “Key Strata and Arch Structure in Unconsolidated Layers” and Its Application 作 者汪 锋 导 师许家林 教授 中国矿业大学 二〇一六年十二月 国家重点基础研究发展计划973项目 2013CB227904） 国家重点研发计划资助项目 2016YFC0501100 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 中图分类号 TD325 学校代码 10290 UDC 622 密 级 公开 中国矿业大学 博士学位论文 采动覆岩结构的“关键层-松散层拱”理论 及其应用研究 Structure of “Key Strata and Arch Structure in Unconsolidated Layers” and Its Application 作 者 汪锋 导 师 许家林 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 岩层移动与绿色开采 答辩委员会主席 张农 评 阅 人 盲审 二〇一六年十二月 论文审阅认定书论文审阅认定书 研究生 汪锋 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 致致 谢谢 五年如白驹过隙转瞬即逝，五年的点滴思绪恍如隔日，一千八百天的坚持终成一 文，叹时光易逝，亦叹韶华难追，曾经的雏鹰，如今的鹏鸟，羽翼未丰，终须翱翔， 风云变化，尚需锤炼，成文之际，感慨万千。执此文，一谢恩师呕心沥血，耳提面命； 二谢至亲万爱千恩，三生报答；再谢同窗管鲍之助，手足情深。 首先诚挚的感谢导师许家林教授。师从五载，收益颇丰。鸟随鸾凤飞腾远，人伴 贤良品自高。恩师渊博的知识、精髓的学术造诣、严谨的治学精神、儒雅的人格魅力 均为学生为人和治学的明灯。论文的选题立意、思路凝练和整个撰写过程中都得到了 许老师的高屋建瓴、严谨细致的指导。恩师渊博的胸怀和学识，为学生营造了宽松的 学习和科研环境，使我能够潜心做事、安心研究。在此，再次向恩师致以崇高的敬意 和衷心的感谢 感谢中国矿业大学矿业工程学院、 煤炭资源与安全开采国家重点实验室窦林名教 授、柏建彪教授、谢文兵教授、王襄禹教授、曹安业副教授、巩思园副研究员在选题 过程中给予的指导和建议 感谢中国矿业大学煤炭资源与安全开采国家重点实验室张少华老师、赵海云老 师、宋万新老师和高杰老师在实验过程中给予的帮助 感谢课题组谢建林副研究员在博士期间论文的选题和撰写及论文结构和思路的 剖析等方面给予无比悉心的指导和帮助， 可以说博士论文的完成同样灌注了谢老师的 心血和汗水感谢课题组王晓振讲师在硕士期间深入煤矿一线进行矿压监测、数据分 析和处理、论文的撰写和修改等方面给予的帮助 感谢课题组朱卫兵副教授、胡国忠副教授、陈大勇讲师、秦伟讲师、鞠金峰讲师 和轩大洋博士后在论文的撰写和修改过程中提供的诸多帮助和宝贵建议。 感谢课题组何昌春博士及步入工作岗位的郭杰凯硕士在论文理论分析中给以的 帮助课题组李竹博士、温家辉、张冬冬、潘海成、朱怡然、刘传振、张广磊、沙猛 猛、季英明、孙邈等硕士以及步入工作岗位的陈梦硕士等在实验室模拟实验及数据处 理、论文校对等方面给予了极大的帮助，真诚的感谢他们感谢课题组其他师弟在日 常学习、生活和工作中给予的帮助 感谢妻子张焕焕女士以及双方父母，正是他们在学习、生活和工作中给予我的支 持、鼓励和帮助，使我能够顺利完成学业 感谢论文引用文献的学术前辈 感谢各位评审专家和答辩委员会专家在百忙之中评审本文， 热切希望得到你们的 指导。 汪 锋 2016 年 12 月 I 摘摘 要要 煤炭开采引起的一系列采动损害与环境问题都与岩层移动有关， 认清采场上覆岩 层移动规律的关键在于揭示采动覆岩承载结构形式及其运动规律。 采动覆岩通常包含 基岩和松散层两部分。 传统上在研究采场上覆承载结构时将上覆松散层简化为均布载 荷作用于基岩，忽略了松散层拱结构引起的岩层载荷分布特征的改变。事实上，我国 华东和华北部分矿区广泛分布着厚度大于 200 m 的松散层地质条件， 此时忽略松散层 拱结构将会导致关键层结构及上覆岩层破断规律及稳定性特征计算结果的失真。 这就 要求建立采动覆岩承载结构时应综合考虑关键层结构和松散层拱结构， 为此本文提出 了采动覆岩结构的“关键层-松散层拱”理论。论文采用理论分析、模拟实验和现场 实测等方法，开展了采动覆岩结构的“关键层-松散层拱”理论及其应用研究。 研究了基岩中关键层结构的承载特性和松散层拱结构的形态特征。 采场上覆基岩 中的承载结构为关键层结构，关键层结构承载后主应力重新分布形成了应力拱，应力 拱是关键层结构发挥承载作用的结果，而非一种承载结构。采场上覆松散层中的承载 结构为松散层拱结构，其形成的临界松散层厚度可以按 1.2Lm-0.9Σh Lm工作面采宽， Σh 基岩厚度 确定。 建立了采动覆岩“关键层-松散层拱”结构的力学模型，得到了考虑松散层拱结 构的主关键层破断时的内力分布的解析式和“砌体梁”结构的稳定性判据。采动覆岩 “关键层-松散层拱”结构阻止了其上覆岩层下沉和变形，同时将上覆岩层载荷向采 空区四周转移，工作面推进过程中，采动覆岩“关键层-松散层拱”结构周期性失稳 并逐渐向上部发展，在主关键层初次破断之前，采动覆岩“关键层-松散层拱”结构 主要影响主关键层的初次破断特征，而当主关键层进入周期破断时，该结构将同时影 响主关键层的周期破断特征和“砌体梁”结构的稳定性。 揭示了采动覆岩“关键层-松散层拱”结构对采场上覆岩层破断失稳的影响机理。 与传统的将上覆松散层简化为均布载荷相比，受松散层拱结构的影响，主关键层的初 次和周期破断距增大，关键块的水平推力增大、剪切力减小， “砌体梁”结构不易发 生滑落失稳， 上覆关键层不会整体复合破断。 修正了松散层载荷折减系数的确定方法， 指导了关键层判别和岩层移动模拟研究过程中松散层等效载荷的计算， 受松散层拱结 构的影响， 在关键层判别和岩层移动模拟实验中， 松散层的载荷不能简化为均布载荷， 其等效载荷等于上覆松散层载荷乘以载荷折减系数。 理论分析结果得到了模拟实验和 祁东煤矿 7130 工作面现场实测数据的验证。 该论文有图 94 幅，表 19 个，参考文献 223 篇。 关键词关键词岩层控制； “关键层-松散层拱” ；覆岩承载结构；绿色开采 II Abstract It is known that mining-induced fractures of roof strata, subsidence, and environmental damage are correlated to longwall mining, which involves large-scale strata movement, which can lead to damage to mining equipment as well as personal injury. The key to comprehensively understanding the evolution of the movement of the overlying strata is to develop a mechanical model of the bearing structures in the overlying strata. The overlying strata consist of the bedrock and the unconsolidated layers. The conventional model for bearing structures was established based on the assumption that the effect of unconsolidated layers can be assumed to be similar to unily distributed loading, while ignoring the variations in the loading stress imposed on the strata owing to an arch structure in the unconsolidated layers ASUL. In fact, a large number of coal mines in eastern and northern China have unconsolidated layers in the overlying strata, and the average thickness of the unconsolidated layers is larger than 290 m. Given these geological conditions, the fractural characteristics of the overlying strata as determined while ignoring the effects of the ASUL do not match those determined through field measurements. More seriously, a number of coal mines in China are prone to significant mining-induced hazards. Therefore, a model for the bearing structure in the overlying strata needs to be established such that it takes into account the key stratum KS in the bedrock as well as the ASUL. With all this in mind, the theory of “Key Stratum-Arch Structure in Unconsolidated Layers” was proposed in this dissertation. This dissertation adopted a comprehensive ology that incorporates theoretical analysis, simulation experiments and field trials to reveal the effects of the “Key Stratum-Arch Structure in Unconsolidated Layers” on fracture and failure of overlying strata. The bearing characteristics of KS and the morphological characteristics of the ASUL were revealed based on the mechanical model. The bearing structure in the bedrock is the KS, and the bearing structure in the unconsolidated layers is ASUL. The stress arch in the overlying strata during excavation is the pattern of the distribution of the maximum principal stress in the KS. The stress arch is not the bearing structure in the bedrock. The critical thickness of the unconsolidated layers for the ation of the ASUL can be derived from 1.2Lm-0.9Σh Lm represents the mining width and Σh is the thickness of the bedrock strata. The mechanical model of the “Key Stratum-Arch Structure in Unconsolidated Layers” was established. The analytic solutions to the primary key stratum PKS and the stability criterion of the voussoir beam structure VBS were derived based on the model of III the “Key Stratum-Arch Structure in Unconsolidated Layers”. The structure of the “Key Stratum-Arch Structure in Unconsolidated Layers” can restrict the overlying strata from moving downward. Further, it transfers the loading stress of the overlying strata to the periphery of the gob area during excavation; this can decrease the loading stress on the lower strata. With the periodic fracture of the PKS, the structure of the “Key Stratum-Arch Structure in Unconsolidated Layers” exhibited periodic failure and grew to the top face of the model; this occurs till the ASUL failed completely. Before the PKS first fracture, the fractural characteristics of the PKS is influenced by the evolution of the “Key Stratum-Arch Structure in Unconsolidated Layers”, while after the facture of the PKS, the fractural characteristics of the PKS and the stability of the VBS are both influenced by the model of the “Key Stratum-Arch Structure in Unconsolidated Layers”. The effects of the “Key Stratum-Arch Structure in Unconsolidated Layers” on fracture and failure of overlying strata were elucidated. In contrast to the results obtained using the previous model established based on the assumption that the effect of unconsolidated layers can be assumed to be similar to unily distributed loading, the fractural interval of the PKS will increase, and the VBS affected will become more stable. The loading reduction factor of the unconsolidated layers was modified based on the “Key Stratum-Arch Structure in Unconsolidated Layers”, which provided a basis of the calculation the equivalent loading of the unconsolidated layers in the process of the KS identification and the physical and numerical simulations. The results of the theoretical calculations were verified through field observations pered in longwall face 7130. This dissertation has 94 figures, 19 tables, and 223 references. Keywords ground control; “key stratum-arch structure in unconsolidated strata”; load-bearing structure; green mining IV Extended Abstract It is known that mining-induced fractures of roof strata, subsidence, and environmental damage are correlated to longwall mining, which involves large-scale strata movement, which can lead to damage to mining equipment as well as personal injury. The key to comprehensively understanding the evolution of the movement of the overlying strata is to develop a mechanical model of the bearing structures in the overlying strata. The bearing structure is a mechanical structure that controls the movement and fracturing of the roof strata during the movement of the overlying strata. The bearing structure can restrict the overlying strata from moving downward. Further, it transfers the loading stress of the overlying strata to the periphery of the gob area during excavation; this can decrease the loading stress on the lower strata. However, the bearing structure exhibits periodic failure, which grows to the surface till the structure fails completely during excavation. The laws governing mining-induced displacement, fracture, stress, and ground pressure are related to the periodic failure of the bearing structure. To date, numerous attempts have been made, both in China and in other countries, to obtain a comprehensive understanding of the mechanical model of the bearing structure. These attempts have been based on the pressure arch hypothesis, the cantilever beam hypothesis, the hinging rock strata hypothesis, the theory of the voussoir beam structure VBS, and the key stratum theory KS. However, the aforementioned hypotheses and theories focus on the bedrock strata and ignore the effect of the bearing structure within the unconsolidated layers. Mechanism models of the VBS and the KS were established based on the assumption that the effect of the unconsolidated layers could be represented as unily distributed loading, while ignoring the variations in the loading stress imposed on the strata owing to an arch structure in the unconsolidated layers. In fact, a large number of coal mines in eastern and northern China have unconsolidated layers in the overlying strata. For example, the average thickness of the unconsolidated layers in 39 coal mines in the Huainan, Huaibei, Wanbei, and Kailuan mining areas is 291 m. Actually, an arch structure in the unconsolidated layers ASUL can during excavation when the unconsolidated layers are thick enough. Given these geological conditions, the fractural characteristics of the overlying strata as determined while ignoring the effects of the ASUL do not match those determined through field measurements. More seriously, a number of coal mines in China are prone to significant mining-induced hazards, including the Xinjulong coal mine, the Liaobaosi coal mine, the Yuncheng coal mine, and the Zhaolou coal mine. Therefore, a model of “Key V Stratum-Arch Structure in Unconsolidated Layers” in the overlying strata needs to be established such that it takes into account the KS in the bedrock as well as the ASUL. With all this in mind, this dissertation adopted a comprehensive ology that incorporates theoretical analysis, simulation experiments and field trials to reveal the effects and the applications of the “Key Stratum-Arch Structure in Unconsolidated Layers” on fracture and failure of overlying strata. The bearing structure in the overlying strata was revealed firstly, which provided a basis of the establishment of structure of the “Key Stratum-Arch Structure in Unconsolidated Layers”. The overlying strata consist of the bedrock and the unconsolidated layers. The bearing structure in the bedrock is the key stratum, and the bearing structure in the unconsolidated layers is ASUL. The stress arch in the overlying strata during excavation is the pattern of the distribution of the maximum principal stress in the KS. The stress arch is not the bearing structure in the bedrock. The conditions for the ation of the ASUL are affected by the mining width Lm, thickness of the bedrock strata Σh, fractural angle of the bedrock strata α, lateral pressure ratio γ, friction angle φ, and cohesion strength C of the unconsolidated layers. Under general conditions, α 60–80, λ 0.5–3.0, C 0–2 MPa, and φ 0–15. The critical thickness of the unconsolidated layers for the ation of the ASUL can be derived from 1.2Lm-0.9Σh. The rise-span ratio and the thickness of ASUL are influenced by lateral pressure ratio, friction angle and cohesion strength of unconsolidated layers. With the increase of lateral pressure ratio, the rise-span ratio of ASUL decreases, but the thickness of ASUL increases. With the increase of friction angle and cohesion strength of unconsolidated layers, the rise-span ratio and the thickness of ASUL decrease. Based on the evolution of the “Key Stratum-Arch Structure in Unconsolidated Layers”, the mechanical model of the “Key Stratum-Arch Structure in Unconsolidated Layers” was established. During the simulation process, a principal strain concentration zone exists on the unconsolidated layers during excavation. The internal and external envelope curves of the principal strain concentration zone make up an ellipsoidal ASUL. With the periodic fracture of the primary key stratum PKS, the ASUL exhibits periodic failure and grows to the top face of the model; this occurs till the ASUL fails completely. The ASUL prevents the overlying strata from subsiding and deing and transfers the loading stress of the overlying strata to its abutment. Given the effect of the ASUL, the distribution of the principal strain can be divided into three zones, namely, the strain-decreased zone, the strain-increased zone, and the original zone. Therefore, the VI loading stress imposed on the PKS can be categorized into three types. The loading stress attributable to the caved unconsolidated layers under the ASUL follows a parabolic function. The loading stress under the abutment of the ASUL is the same as the advanced abutment stress along the longwall face. Finally, the loading stress outside the ASUL is still in the in-situ stress state. According to the evolution of the “Key Stratum-Arch Structure in Unconsolidated Layers”, the mechanical model of the “Key Stratum-Arch Structure in Unconsolidated Layers” consists of the first fracture model of PKS in “Key Stratum-Arch Structure in Unconsolidated Layers” and the period fracture model of PKS in “Key Stratum-Arch Structure in Unconsolidated Layers” In the er mechanical model, the fractural characteristics of the PKS is influenced by the evolution of the “Key Stratum-Arch Structure in Unconsolidated Layers”, while in the latter model, the fractural characteristics o