特厚煤层坚硬顶板破断动载特征及弱化控制研究

It is abundant with the reserves of extra-thick coal seam in China. It is of great significance to realize safe and efficient mining of extra-thick coal seams for ensuring the sustainable supply of coal. Overburden structure and its breakage characteristics in Extra-thick Coal Seam Mining have significant influence on regional strata pressure appearance such as working face and goaf roadway. At present, fully mechanized top-coal caving mining with large mining height has been widely and successfully applied to the mining of Extra-thick Coal seams. However, the layout of roadways along the goaf side and the control of surrounding rocks have not been effectively solved. Overburden breakage has a significant dynamic load on roadways, and the safety maintenance of roadways seriously restricts the safe and efficient production of mines. Therefore, this subject mainly carries out the following research: (1) dynamic monitoring and analysis of the distribution characteristics of mining support stress and its evolution with the advancing of the working face in Extra-thick Coal seam, establishing a similar experimental model of mining in Extra-thick Coal Seam under typical conditions, and exploring the characteristics of overburden breakage and dynamic load formation mechanism; (2) building a single overburden stratum in Extra-thick Coal Seam Based on rock dynamics theory The theoretical model of dynamic stress wave transmission for multi-layer breaking reveals the relationship between dynamic load intensity of lower roadway and dynamic load intensity of overburden breaking; (3) The numerical calculation model of roadway surrounding rock stability under dynamic and static load coupling is established, the dynamic response characteristics of roadway support structure are studied, and the corresponding weakening control technology is developed to provide reference for safe and efficient mining of Extra-thick Coal seam.

我国特厚煤层储量丰富，实现特厚煤层安全高效开采对保障煤炭持续供应意义重大。特厚煤层开采覆岩结构及其破断特征显著影响工作面及临空巷道等区域矿压显现。目前，大采高综放开采己广泛并成功应用于特厚煤层工作面开采，但是，沿空侧巷道布置方式和围岩控制等难题尚未有效解决，覆岩破断对巷道的动载作用显著，巷道安全维护严重制约矿井的安全高效生产。因此，本课题主要开展以下研究：（1）动态监测并分析特厚煤层工作面采动支承应力分布特征及随工作面推进的分布演化规律，建立典型条件下特厚煤层开采的相似试验模型，探究其覆岩破断特征与动载形成机制；（2）基于岩石动力学理论建立特厚煤层覆岩单层和多层破断的动载应力波传递理论模型，揭示下位巷道动载强度与覆岩破断动载源强度之间的关系；（3）建立动静载耦合作用下巷道围岩稳定的数值计算模型，研究巷道支护结构的动力响应特征，开发相应的弱化控制技术，为特厚煤层的安全高效开采提供参考。

我国西部朔南矿区煤层厚度大、开采条件复杂，煤层上方赋存有多层坚硬难冒放顶板，在煤层开采过程中，采场尤其是采空区后方沿空巷道呈现强烈动力显现特征，严重威胁矿井安全。本项目综合采用现场调研、理论分析、数值模拟、相似模拟及现场试验等手段，系统研究了坚硬顶板条件下特厚煤层综放开采的矿压显现特征及动载作用机理，提出了基于水压致裂和抗动载作用支护系统的弱化控制原理和技术途径。经过团队3年研究，发表与项目相关的学术论文10篇，其中，SCI收录7篇，EI收录2篇，授权国内外发明专利8项，实用新型专利8项，获批软件著作权3项，获得科技奖励5项。具体成果如下：（1）受煤岩地质构造特征和开采技术条件影响，特厚煤层开采工作面来压强度大、煤壁片帮、支架损坏，呈现出强弱交替的大、小周期来压规律；沿空巷道强烈位移、支护结构严重破坏，表现出阶段性的动载变形特征；（2）理论判定并现场验证了特厚煤层上覆岩层主关键层的位置，建立了坚硬顶板破断的动载作用模型，揭示了下位采场及沿空巷道动载强度与上覆坚硬顶板破断动载源强度之间的关系，确定了采场和沿空巷道强烈动载特征的主要控制因素；（3）研究得到了特厚煤层双硬顶板垮落方式和垮落步距，确定了特厚煤层双硬顶板破断失稳呈现下位“短悬臂梁”与上位“长砌体梁”结构，揭示了特厚煤层双硬顶板的非复合效应以及双硬顶板的断裂线同步时采场顶板双滑落失稳机理；（4）分析了不同属性、不同方向的动载应力波对巷道围岩稳定的影响规律，提出了动载应力波之间的相互叠加效应诱发巷道迎波侧和背波侧出现拉应力并产生积累损伤和强烈变形，是巷道围岩的危险部位；揭示了巷道围岩分别在有、无支护和动、静载作用条件下的动力响应特征；（5）研究了不同水压致裂方式的作用效果，提出了坚硬顶板水压致裂弱化控制技术，确定了合理的施工工艺和关键参数；建立了以高强蛇形让压吸能锚杆为核心的抗动载支护系统和设计方法，将研究技术应用于工程实践。