采动影响下深部煤层底板卸荷劣化破坏机制研究

In order to obtain deformation and failure mechanism of deep coal seam floor under unloading, the research will be carried out from collaborative analysis perspective of macro mechanics and micro mechanics. Mining-induced stress variation characteristics of floor in different depth under different stages of strata pressure will be concluded by analysis of deep coal floor field observation data. Based on this, the rock mechanics test of floor under unloading condition will be carried out. Mechanical deterioration laws of rock in mining unloading will be analyzed. On the basis of mechanical deterioration laws, taking acoustic emission monitoring results and specimen failure characteristics into consideration, the constitutive relation of deep coal seam floor under unloading deterioration will be constructed. The numerical calculation module for constitutive model of deep coal seam floor under unloading deterioration will be developed by computer programming technology. The mining-induced stress evolution law of numerical simulation test corresponding to rock mechanics test will be carried out. Based on the comparison between numerical simulation test results and rock mechanics test, the numerical calculation module of deep coal seam floor in mining unloading will be refined. Numerical model of deep coal seam floor will be calculated. The energy evolution and deformation failure characteristics of floor will be analyzed. The mechanics model of unloading failure of deep coal seam floor will be built by damage-fracture mechanics. The deformation and deterioration failure mechanism of deep coal seam floor under the influence of mining unloading will be revealed. The constitutive model and damage-fracture mechanics model which can reflect unloading failure essence of deep coal seam floor will have important theoretical and realistic value for deformation and failure mechanism of deep coal seam floor.

针对采动卸荷影响下深部煤层底板变形破坏机理这一理论难题，从宏观和细（微）观协同分析的角度开展研究。基于深部煤层底板现场观测数据分析得出不同矿压显现阶段、距煤层底板不同深度的煤（岩）体应力变化特征，开展加卸载路径下的岩石力学试验，分析采动卸荷作用下岩石力学参数的劣化规律。在此基础上，结合声发射监测结果和试件变形破坏特征，建立深部煤层底板卸荷劣化本构关系；运用计算机编程技术开发深部煤层底板卸荷劣化本构模型的数值计算模块；开展岩石力学试验加卸载路径对应的数值模拟试验，对比试验结果，修正并完善数值计算模块；建立深部煤层底板数值模型，分析底板能量演化规律及变形破坏特征，同时运用损伤断裂理论构建深部煤层底板采动卸荷破坏力学模型，揭示采动卸荷作用下的深部煤层底板劣化破坏机理。建立能反映深部煤层底板采动卸荷劣化实质的本构模型和损伤断裂力学模型，对于深部煤层底板变形破坏机制研究具有重要的理论意义和现实意义。

本项目针对深部煤层底板滞后破坏的问题，以邯邢矿区为研究对象，研究了深部煤层底板岩体采动过程中应力变化特征，论证了采动卸荷过程中深部煤层底板岩体卸荷劣化破坏特征，得到了深部煤层底板力学参数卸荷劣化是深部煤层底板岩体发生滞后破坏的主要影响因素之一。构建了深部煤层底板应力分布力学模型，分析了深部煤层底板采动应力演化特征，在此基础上，利用损伤力学理论，推导了煤层底板损伤的本构关系及损伤函数进行了推导，获得了不同阶段的底板岩层力学参数损伤劣化的分布规律；构建了考虑原生裂纹面滑移变形和翼状裂纹扩展的断裂力学模型，推导出考虑裂纹滑移扩展变形的损伤因子理论公式，揭示了损伤劣化影响下深部煤层底板岩体承载能力变化规律；运用悬臂梁模型分析了裂纹面间锁固段的变形破坏特征，揭示了深部煤层底板采空区滞后突水机理；开展了不同应力路径下岩石弹性模量劣化力学试验，从能量角度揭示了采动过程中深部煤层底板岩体卸荷劣化机制；通过多参量现场实测工作，构建了煤层底板全空间点-线-面协同监测模式，揭示深部煤层底板变形破坏的分带性；构建了深部煤层底板突水危险性预测模型。项目研究与生产实际相结合，有效地指导了煤矿安全生产，取得了显著的经济效益和社会效益。项目研究期间，共发表学术论文9篇，受理发明专利3项，获省部级科技奖2项，培养硕士研究生1人；参加国内国际学术会议5人次。项目研究成果不仅为深部煤层底板突水机理研究提供技术支撑，而且为煤矿安全带压开采煤层底板突水预测及水害防控工程实际提供科学依据。