深井沿空留巷实体煤帮渐进劣化力学特性及稳定机理研究

The solid coal rib in deep gob-side entry retaining subjected to loading and unloading from mining-induced stress is with great deformation and low stability, which can result in the failure of deep gob-side entry retaining for depressurized mining. Therefore, this study is focused on the gradual mechanical property deterioration and stability mechanism of solid coal rib in deep gob-side entry retaining. The mechanical model involving the main roof and the solid coal rib in deep gob-side entry retaining will be established subjected to the supporting and roof-cutting action of the roadside backfill body. The stability influence factors and influence law for the key block of the main roof lateral breakage will be analyzed to expound the formation mechanism of the main roof lateral breakage structure. Then, multi-stage failure triaxial test with confining pressure unloading for the damage coal sample under the condition of deep gob-side entry retaining stress evolution will be conducted to reveal the gradual mechanical property deterioration of the solid coal rib. To obtain deformation mechanism of the solid coal rib, the deformation characteristics and the stress evolution in deep gob-side entry retaining will be analyzed with the numerical model based on the triaxial test results and in-mine monitoring results. Finally, a stability criterion for plastic solid coal rib in deep gob-side entry retaining will be proposed. By analyzing the dynamic response characteristics of the solid coal rib support structure subjected to the loading and unloading of the mining-induced stress, the stability mechanism of the solid coal rib in deep gob-side entry retaining will be expounded. Thus, the findings of the study would shed lights on the surrounding rock stability control technology for gob-side entry retaining.

受深井采动应力多次加卸荷作用的沿空留巷实体煤帮变形大、稳定性差，是制约深井沿空留巷卸压开采实施的关键问题之一。为此，开展深井沿空留巷实体煤帮力学性能劣化规律及稳定机理研究，首先考虑巷旁充填体的支撑、切顶作用，建立包括实体煤帮、巷旁充填体的深井沿空留巷基本顶与实体煤帮相互作用力学模型，分析基本顶侧向破断后形成的关键块体结构的稳定性影响因素及影响规律，阐明基本顶侧向破断结构的形成机制；根据深井留巷实体煤帮采动应力变化特征，开展损伤煤样多级破坏三轴卸围压试验，揭示实体煤帮渐进劣化力学特性，依据校验数值计算模型，进而分析实体煤帮的变形特征和应力分布规律，揭示深井沿空留巷实体煤帮变形机理；最后研究塑性状态深井沿空留巷实体煤帮的稳定性判别准则，分析采动应力多次加卸荷作用下深井沿空留巷实体煤帮支护结构的动态响应特征，揭示塑性状态深井沿空留巷实体煤帮稳定机理。研究成果可为深井沿空留巷围岩稳定控制提供依据。

受采动应力多次加卸荷作用的深井沿空留巷实体煤帮变形大、稳定性差，是制约深井沿空留巷卸压开采实施的关键问题之一。本课题综合采用现场实测、实验室试验、理论分析、数值模拟、工业性试验等方法，系统研究深井沿空留巷实体煤帮力学性能劣化规律及稳定机理，主要研究成果为：.（1）建立了包括实体煤帮、巷旁充填体的深井沿空留巷基本顶与实体煤帮相互作用力学模型，分析了基本顶侧向破断后形成的关键块体结构的稳定性影响因素及影响规律，探讨了实体煤帮力学特性和支护阻力对基本顶关键块体二次破断位置和稳定性的影响规律；.（2）基于对深井留巷实体煤帮力学介质的评估，开展了损伤煤样多级破坏三轴卸围压试验，建立了深井留巷实体煤帮煤样应变软化本构模型，并实现了在FLAC3D当中的数值计算，研究了留巷实体煤帮的变形特征和应力分布规律，揭示了深井沿空留巷实体煤帮变形机理。.（3）采用数值计算和理论分析的方法，分析了采动应力多次加卸荷作用下深井沿空留巷实体煤帮支护结构的动态响应特征，建立了极限平衡状态下锚网支护实体煤帮保持稳定的支护阻力计算式，提出了塑性状态深井沿空留巷实体煤帮的稳定性判别准则，揭示了塑性状态深井沿空留巷实体煤帮稳定机理。