深部煤巷围岩三向应力差异时空梯度驱动损伤失稳机制

Deep coal and rock mass is in high stress environment. The roadway excavation break the original triaxial stress balance, which leads to creep instability of surrounding rock or rock burst disaster. It intends to research along the main line that surrounding rock damage and instability is driven by spatial-temporal gradient of triaxial stress difference, with the method of rock mechanics experiment, theoretical analysis, numerical simulation combined with field measurement. It start with different triaxial stress test of coal specimens with different mechanical properties under different stress conditions, analyze its relationship between damage characteristics with triaxial stress difference rate and transition speed in the loading and unloading process. Establish analysis model about surrounding rock spatial-temporal gradient of triaxial stress difference, and analyze its dynamic evolution law. Reveals the surrounding rock damage failure process and mechanism driven by spatial-temporal coupling gradient of triaxial stress difference. Deduce the threshold intervals corresponding to different forms of instability (creep instability and rock burst). Establish the mechanical criteria for surrounding rocks with different mechanical properties and instability forms based on spatial-temporal coupling gradient of triaxial stress difference. The research results are of great significance for exploring the mechanism of surrounding rock instability and rock burst disaster in deep roadway, determining the supporting mode and parameters reasonably, and improving the effect of rock burst prevention and control.

深部煤岩体处于高应力环境下，巷道开掘破坏了原有三向应力均衡状态，导致围岩蠕变失稳或发生冲击地压灾害。以围岩三向应力差异时空梯度驱动损伤失稳为主线，通过岩石力学试验、理论分析、数值仿真模拟结合现场实测等手段，从测试不同力学属性煤样不同应力环境下三轴差异应力加卸载产生的损伤破坏特征与三向应力差异率、变化速率的关系入手，建立围岩三向应力差异时空梯度（场）分析模型并分析其动态演变规律，揭示围岩三向应力差异时间-空间梯度耦合驱动损伤失稳过程和机理，推导不同失稳形式（蠕变失稳和冲击地压）对应的阈值区间，构建基于围岩三向应力差异时空梯度的不同力学属性围岩产生不同形式失稳的力学准则。研究成果对于探索深部巷道围岩失稳和冲击地压致灾机制，合理确定深部巷道支护方式和参数，提高冲击地压防治效果具有重要意义。

深部煤岩体处于高应力环境下，巷道开掘破坏了原有三向应力均衡状态，导致围岩蠕变失稳或发生冲击地压灾害。以围岩三向应力差异时空梯度驱动损伤失稳为主线，从测试不同力学属性煤样不同应力环境下三轴差异应力加卸载产生的损伤破坏特征与三向应力差异率的关系入手，建立围岩三向应力差异时空梯度（场）分析模型并分析其动态演变规律，揭示围岩三向应力差异时间-空间梯度耦合驱动损伤失稳过程和机理，推导不同失稳形式（蠕变失稳和冲击地压）对应的阈值区间，构建基于围岩三向应力差异时空梯度的不同力学属性围岩产生不同形式失稳的力学准则。基于深部三向等压状态岩体有无限大强度的特性，通过岩石力学试验、理论分析、数值仿真模拟结合现场实测等手段，研究了不同应力路径下的煤体单元体响应特征，得到单元体失稳的应力差异判据，进一步提出煤巷围岩应力差异梯度Dg和应力差异梯度变化率Dgc的概念，基于Drucker-Prager准则分析了巷道围岩Dg演化特征，进而得到巷帮煤体Dg集中致冲的作用机理，对防冲机制和冲击事故案例进行了分析。结果表明：煤体的应力差异承受能力随着应力路径的不同而存在显著差异；应力差异梯度Dg随埋深增大和煤层冲击倾向性等级升高而增长，体现出明显的“上升-跌落-下降”梯度性质；帮部煤体应力差异梯度变化率满足Dgc≥[Dgc]时达到冲击启动条件，应力差异梯度峰值Dgmax驱动弹性区或塑性区煤体发生瞬时强破坏、失稳、冲出；巷帮煤体冲击是巷道围岩变形、破坏的一种极端演化形式；防冲机制以弱化围岩Dg水平为根本，以Dgc控制为主要着力点。研究成果对于探索深部巷道围岩失稳和冲击地压致灾机制，合理确定深部巷道支护方式和参数，提高冲击地压防治效果具有重要意义。