| 浅埋煤层过沟开采覆岩裂隙与地表裂缝演化规律数值模拟 |
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| 引用本文： | 魏江波,王双明,宋世杰,孙强.浅埋煤层过沟开采覆岩裂隙与地表裂缝演化规律数值模拟[J].煤田地质与勘探,2022,50(10):67-75. |
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| 作者姓名： | 魏江波 王双明 宋世杰 孙强 |
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| 作者单位： | 1.西安科技大学 地质与环境学院，陕西 西安 710054 |
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| 基金项目： | 国家自然科学基金项目(41402308)；榆林市科技计划重大项目(6130819001)；陕西省煤炭绿色开发地质保障重点实验室重点基金项目(DZBZ2022Z-03) |
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| 摘 要： | 浅埋煤层过沟开采在陕北矿区普遍存在，严重威胁着矿井安全生产和生态健康发展。覆岩采动裂隙及地表裂缝的发育是岩体微裂隙的延伸和扩展的结果，为更加系统地研究浅埋煤层过沟开采覆岩微裂隙的演化规律，以陕北安山井田125203工作面为背景，根据现场沟道剖面及钻孔资料，采用Particle Flow Code (PFC)数值模拟平台构建颗粒流数值采煤模型，模拟分析覆岩微裂隙的发育特征、数量变化规律和力链演化特征，揭示微裂隙的发育规律和地表裂缝发育机理。结果表明:浅埋煤层过沟开采过程中，覆岩微裂隙发育表现为“产生–延伸和扩展–聚合成群–贯通成缝”的动态演化过程；根据微裂隙的基本发育特征及分布规律，可将发育全程划分为非连续跳跃式、连续贯通式和横向扩展式3个微裂隙发育阶段；覆岩微裂隙数量随工作面推进距离的增大而增多，非连续跳跃式和连续贯通式发育阶段呈现指数增长特征，分别累计发育微裂隙547和2 867条，覆岩微裂隙逐渐发育至地表；横向扩展式发育阶段呈线性增长特征，累计发育微裂隙11 705条，微裂隙数量随岩层高度的增大而减小；覆岩力链演化过程中，强黏性力链的破坏致使微裂隙发育，局部产生应力集中，强黏性力链拱自下而上逐渐破坏并贯通至地表，导致微裂隙延伸发育至地表形成地裂缝，力链在未贯通岩层的微裂隙两侧和尖端及地表裂缝两侧形成强力链区，微裂隙处形成弱(无)力链区。该研究成果可为陕北矿区浅埋煤层过沟开采覆岩及地表损害防控提供理论指导。
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| 关 键 词： | 浅埋煤层 过沟开采 裂隙演化 地裂缝 颗粒流 强力链 |
| 收稿时间： | 2022-03-08 |
Numerical simulation on evolution law of overburden fractures and surface cracks in crossing ditch mining of shallow coal seam |
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| Institution: | 1.College of Geology and Environment, Xi’an University of Science and Technology, Xi’an 710054, China2.Shaanxi Provincial Key Laboratory of Geological Support for Coal Green Exploitation, Xi’an University of Science and Technology, Xi’an 710054, China3.Geological Research Institute for Coal Green Mining, Xi’an University of Science and Technology, Xi’an 710054, China |
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| Abstract: | Crossing ditch mining of shallow coal seam is common in northern Shaanxi mining area, which seriously threatens the safe production and the sound ecological development. The mining-induced overburden fractures and surface cracks are developed as a result of the extension and expansion of microcracks in rock mass. In order to more systematically study the evolution law of overburden microcracks in crossing ditch mining of shallow coal seam, a numerical model of particle flow in coal mining was established with the Particle Flow Code (PFC) numerical simulation platform according to the field ditch profile and borehole data under the background of 125203 working face of Anshan Coal Mine. Meanwhile, the development characteristics, quantity change laws and force chain evolution characteristics of overburden microcracks were simulated and analyzed. Besides, the development laws of microcracks and the development mechanism of surface cracks were revealed. The results show that: the development of overburden microcracks is characterized by the dynamic evolution process of “generation-expansion and extension-aggregation in groups-penetrating to form cracks” during the crossing ditch mining of shallow coal seam. According to the basic development characteristics and distribution law of microcracks, the whole process of development could be divided into the 3 stages of the discontinuous skipping stage, the continuous penetrating stage and the horizontal expansion stage. Besides, the number of overburden microcracks increases with the increasing of advancing distance of coal working face, with exponential growth characteristics shown in the discontinuous skipping and continuous penetrating stages of microcracks, in which 547 and 2 867 microcracks are developed cumulatively, and the overburden microcracks gradually develop to the surface. Linear growth characteristics are shown in the horizontal expansion stage, in which 11 705 microcracks are developed cumulatively, and the number of microcracks deceases with the increasing height of rock stratum. During the evolution process of the overburden force chain, the failure of strong viscous force chain leads to the development of microcracks and local stress concentration. The strong viscous force chain arch gradually breaks down from bottom to top and penetrates to the surface, resulting in the extension and development of microcracks to the surface to form ground fissures. In addition, strong force chain areas are formed on both sides and the tip of microcracks that do not penetrate through the rock layers and on both sides of surface cracks, and weak (no) force chain areas are formed at the microcracks. In general, the research results could provide theoretical guidance for the crossing ditch mining of sallow coal seam and the prevention and control of damage to overburden and surface in northern Shaanxi mining area. |
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