新疆绿洲矿区特厚煤层保水开采机理与分类研究

The coal resources and water resources are very rich in Yili District of Xinjiang, which has become one of seven coal chemical industry bases in China, and Yili Mining Area is the only oasis mining area of five large-scale coal mining bases in Xinjiang. While the problem of aquifer-protection mining for coal resources is the first difficult problem to be solved for economic development in Yili district. Based on the geological conditions and occurrence conditions of coal seams in Yili Mining Area, the space-time dynamic evolution characteristics of mining-induced fractures will be clearly analyzed by reasonably using advanced physical simulation and numerical calculation method. The upper aquiclude movement, middle constrained strata effect and underlying main roof activity will be unified, then establishing mechanical model of key stratum structure, revealing aquifer-protection mining mechanism of oasis mining area while mining parameters (such as face advance direction of coalface, inclined length, advancing speed, mining height and so on) changed and second mining-induced movement of ultra-thick coal seam using layer mining, constructing aquifer-protection mining technology and its classification index system of ultra-thick coal seam in oasis mining area. The research results could guide coordination development between large-scale coal mining and water resources protection in Yili Mining Area, found new mode of aquifer-protection mining for oasis mining area, provide theoretical guidance and technical support for successful development of aquifer-protection mining technology in ecological fragile mining areas of Xinjiang and even the national mining areas with similar conditions.

新疆伊犁地区煤炭资源与水资源丰富，已成为全国七大煤化工基地之一，伊犁矿区是新疆五大煤炭生产基地中唯一的"绿洲"矿区。煤炭资源保水开采问题是伊犁地区经济发展面临的首要难题。基于伊犁矿区的地质条件和煤层赋存条件，合理利用先进的物理模拟和数值计算手段，分析清楚覆岩采动裂隙时空动态演化特征；将覆岩上位隔水层运移、中位"阻隔岩层"效应和下位基本顶活动统一起来，建立覆岩关键层结构力学模型，分析关键层运动全过程与"阻隔岩层组"耦合关系，揭示开采参数(工作面推进方向、倾斜长度、推进速度、采高等)变化时绿洲矿区保水开采机理和特厚煤层分层二次采动保水开采机理，构建绿洲矿区特厚煤层保水开采技术及其分类指标体系。研究成果可指导伊犁矿区煤炭大规模开采与水资源优质保护协调发展，可创立绿洲矿区"保水开采"新模式，可为新疆生态脆弱矿区乃至全国类似条件矿区保水开采技术的成功开发提供理论指导和技术支持。

针对伊犁矿区煤炭资源大规模开发过程中的水资源保护问题，根据伊犁矿区煤田分布和地质特征，确定伊犁一矿、四矿为项目研究基地。基于地层结构特征及煤岩力学性质测试结果，通过建立覆岩移动物理模型、覆岩结构整体力学模型、覆岩裂隙发育与地表沉陷数值分析模型、固液耦合物理模型，在分析伊犁矿区特厚煤层开采过程中覆岩的破断、移动规律及裂隙时空动态演化特征的基础上，重点研究了不同开采参数条件下“阻隔岩层组”对覆岩采动裂隙的控制作用，总结和提出了伊犁矿区保水开采机理及适用条件的分类指标，并初步构建了该矿区特厚煤层保水开采技术体系。主要成果包括：（1）确定第四系含水层为保水开采目标含水层，新近系中下部粘土层为关键隔水层，伊南矿区存在关键层结构，而伊北矿区不存在关键结构。（2）初次采动条件下的老顶初次断裂步距35~50 m、周期断裂步距10~15 m，覆岩块体二次破断形式包括静载荷和冲击载荷（自由落体式、转动坠落式）破断。（3）理论推导了静载荷和冲击载荷作用下关键层块体的失稳判据及伊南矿区亚关键层结构不发生失稳的煤层临界开采厚度为6.9 m。（4）因软弱岩层与坚硬岩层的结构耦合效应，覆岩裂隙随工作面推进呈跳跃式发展直至地表，除切眼和停采线以外覆岩裂隙总体呈先张开再闭合的规律，切眼和停采线是长壁工作面保水防溃的关键区域。（5）通过开发固液耦合相似模拟实验可视化系统及隔水层模拟材料，实验得出了采动条件下含水层的渗流特征及隔水层稳定性演化规律。（6）厚煤层的分层厚度、采动次数及充填方式对覆岩裂隙的时空动态演化和地表沉陷影响显著，是实现保水开采的关键。（7）确定覆岩层厚度、岩体完整性等七个指标为保水开采适用条件的分类指标，并由此初步构建了以工作面分区布置、关键区域处理及开采参数控制保水开采技术体系。以上研究成果为厚煤层保水开采机理与技术的提出奠定了基础，对新疆生态脆弱矿区建设具有积极意义。