煤巷掘进工作面围岩加卸载力学特性的掘进速率效应

Driving rate, determining the rate and interval of loading and unloading of surrounding rock at heading faces, and also controlling the transient stress state during excavation, is the most vulnerable and critical technical parameter during advancement of coal roadway, which inevitably results in different mechanical characteristics of surrounding rock due to the difference of loading and unloading path. Therefore, the effort of this subject would be made on the field measurement of stress development based on different driving rate during advancement of coal roadway, and on the analysis of transient mechanical state during excavation of rock and coal mass, stress transition in surrounding rock and final stress distribution; and then the loading and unloading process of surrounding rock could be presented. Mechanical mechanism of the effect of driving rate on the loading and unloading mechanical characteristics of rock and coal mass could be discovered by studying on mechanical behavior under multi-stage loading-unloading conditions in lab. These research findings could enrich tunneling pressure theory, and provide theoretical foundation for safe driving and stability control of coal roadway, which has significantly instructive and great reference meaning for realizing safety production in coal mines.

掘进速率是煤巷掘进过程中最易变化的关键技术参数，掘进速率决定了掘进工作面围岩重复加卸载速率及时间间隔，也决定了开挖时围岩所处的瞬时应力状态，掘进速率不同造成的围岩加卸载路径差异必然导致围岩呈现不同的力学特性，对掘进安全和巷道维护有重要影响。本项目基于不同掘进速率煤巷掘进应力分布现场实测，结合数值模拟研究不同掘进速率条件下巷道煤岩体开挖瞬时力学状态、煤岩体应力转移过程及最终应力分布状态，获得不同掘进速率条件下巷道围岩应力场演化及煤岩体加卸载规律，据此制定反映不同掘进速率影响的煤岩体加卸载实验方案，通过力学实验分析不同加卸载条件下煤岩体力学行为及加卸载后力学特性，揭示掘进速率对巷道煤岩体加卸载力学特性的影响机制。研究成果可丰富掘进巷道矿压理论，并为煤巷安全掘进和围岩稳定性控制技术提供理论依据，对实现煤矿安全生产具有一定的指导和借鉴意义。

巷道掘进和维护是保障煤矿采掘平衡和安全生产的基本前提，掘进速率是影响煤巷掘进及围岩稳定性控制的关键技术参数，为保障掘进安全和巷道维护，有必要深入研究掘进速率对巷道周边煤岩体的应力分布及力学特性的影响规律。基于此，本项目选取了地质条件和开采技术条件相同、掘进速率不同的煤巷掘进工作面，开展了不同掘进速率条件下煤层应力分布的现场测试；采用数值模拟分析了不同掘进速率条件下掘进工作面围岩应力场演化规律；通过力学分析揭示了掘进速率对围岩应力分布的影响作用，并开展了不同加卸载条件下煤岩样力学特性实验；揭示了掘进速率对巷道煤岩体加卸载力学特性的影响机制。研究发现，巷道掘进过程中，围岩应力分布呈现明显的时间效应，推进速率对掘进工作面附近煤岩体的应力分布及损伤状态有直接影响，与周边煤岩体受掘进扰动影响程度呈反比，适当提高掘进速率有利于提高围岩的自身承载能力及稳定性。研究成果对巷道掘进及围岩稳定性控制工程实践有一定的理论指导意义。