三场视角下超大采高综采覆岩破断及矿压显现的渐进式演化机理研究

Due to the large mining height for thick coal seams, mining-induced stress becomes more severe at the working face, which brings new challenges to supporting demands, especially for the roof and ribs. Such severe phenomenon is essentially related to the gradual evolution of mining-induced stresses, fracture and breakage of strata over the mined-out area. By integrating stress field, fracture field and energy field induced from large mining height, this project aims to reveal the evolution mechanism of overlying strata movement and mining-induced stress distribution. The research will be performed by a combination of large-scale physical modeling and discrete element modeling. The research will focus on two aspects. The first aspect focuses on the stress-fracture-breakage. From the stress evolution perspective, the micro mechanical mechanism of strata breakage will be investigated, and the mechanical causes of fracture generation and propagation will be examined, aiming to correlate the micro mechanism of fracture development and the strata macro breakage phenomena. The second aspect is initiated from the stress-fracture-energy perspective. Energies within the strata, rib, supports, waste rock, and the floor form an integral energy transform system. By identifying the energy evolution process in each of these elements, the energy accumulation, transformation, and dissipation process will be revealed, and the strata-supports interaction mechanism can be interpreted from the perspective of energy evolution.

超大采高综采工艺机采高度显著增加，采煤工作面矿压显现强烈，采场支护体工况复杂，顶板与煤壁等围岩控制难度增大。上述矿压现象的实质是应力、裂隙、破断等因素的渐进式演变过程，本项目拟将采动应力场、裂隙场、能量场等三场合一，开展“三场”视角下超大采高综采覆岩破断及矿压显现渐进式演化机理研究。采用实验室大比尺模型试验、离散元模拟等研究方法，一是围绕“应力—裂隙—破断”研究主线，从应力演化的角度阐释覆岩破断的细观力学机制，探究覆岩微裂隙萌生扩展的力学成因，开展裂隙扩展的细观机制与岩层宏观破断的关联性研究。二是基于“应力—裂隙—能量”研究视角，跟踪覆岩不同区域的能量演化过程，构建“覆岩—煤壁—支架—矸石—底板”五位一体的能量积聚耗散系统，揭示采动能量场“积聚—迁移—耗散”闭环转化过程，从能量场演化的视角阐释围岩与支架的相互作用机理。项目研究成果将为超大采高综采工艺与装备的发展提供亟需的基础理论支撑。

项目以超大采高综采覆岩破断与矿压显现的渐进式演化机理为研究主线，聚焦采动过程中“三场”渐进式演化特征。研制了高刚度、可旋转式采场模型试验平台，形成了与之配套的超大采高综采模型试验高精度测试方法，包括模型内部应力测试装置、液压支架模拟装置、采场超前支承压力监测装置、模型表面位移高精度监测装置等。研制了适于大比尺模型试验的SGC型相似材料配比方案。上述要素为开展模型试验研究提供了可靠的支撑平台。以典型地层的大采高综采采场覆岩为工程背景，在实验室完成了8架次超大采高大比尺采场相似模型试验。基于模型试验结果，揭示了采动应力场的拱形演化特征，阐释了厚硬岩层对于宏观应力场演化的影响机制。阐明了采场覆岩破断与采动应力演化的梁拱二元结构，得到了覆岩破断与应力场演化的关系，揭示了覆岩破断与矿压显现的渐进式演化机理。构建了大采高综采覆岩“悬臂梁-层间岩层-砌体梁”结构模型，提出了基于“顶板-煤壁-支架”综合评价的大采高支架选型设计方法。构建超大采高工作面覆岩全柱状地层模型，完成了采场矿压显现特征的UDEC-Trigon离散元模拟研究。开发了覆岩裂隙场数值计算模块，实现了覆岩采动裂隙的动态捕捉及裂隙场演化的量化表征，揭示了覆岩采动裂隙场的分区演化机制。开发了覆岩能量场数值计算模块，揭示了覆岩采动能量场的“积聚-迁移-耗散”演化机制。上述成果对于采场支承压力分布、坚硬顶板治理、采场动力灾害风险评估及防控等方面具有理论指导意义。研究成果已应用于晋煤集团寺河矿、陕煤集团曹家滩矿等多个大采高工作面的采煤工艺优化设计、装备选型配套、采场围岩控制，取得了较好的实践效果。发表SCI/EI论文10篇，授权专利2项，获批软件著作权证书2项。培养毕业博士2名，硕士1名。