深井巷道破裂围岩力学特性及大变形破坏机理

Deep mine roadway is in the complex mechanical environment of the three "high" and one "disturbance",the prominent characteristic of surrounding rock is loading after it was broken and long-term deformation. Study on the mechanical properties and large deformation failure mechanism of broken surrounding rock is a key question of surrounding rock stability control principle and technology.In this research project, physical simulation achievements (the actual loading-unloading stress paths and stress states of surrounding rock in different depths of broken zone) will studied be as the breakthrough point, the quantitative relationship between breaking degrees of broken surrounding rock and its decreased degree of deviatoric stress at post-peak will be established, and a new preparation method of broken rock sample will be put forward. Based on this study, a series of broken rock sample will be prepared, these samples are correspond with broken surrounding rock in different depths of broken zone. According to the stress states of broken surrounding rock, the loading stress paths will be designed, the MTS machine and the triaxial rheology testing system will be applied separately to obtain the short-term and long-term ( rheological ) mechanical properties of broken surrounding rock of deep mine roadway, and new short-term strength theory and rheological model of it will be separately advanced. A new concept of the volume expansion ratio will be defined to quantify breaking degrees of broken surrounding rock. The function between the volume expansion ratio and each parameters of the new short-term strength theory and rheological model will be separately established, and the inner law of breaking degrees and the mechanical parameters of broken surrounding rock will be revealed. Based on the above achievements, the dilatancy properties of broken surrounding rock of deep mine roadway will be explained, and the large deformation failure mechanism of it will be achieved from the dilatancy and rheology perspective.The project achievements can provide theoretical guidance for new supporting technology in surrounding rock stability control of deep mine roadway.

深井巷道处于"三高一扰动"的复杂力学坏境中，围岩特点为破裂后承载且长期变形不止，破裂围岩力学特性及大变形破坏机理是事关深井巷道围岩稳定控制原理与技术的关键问题。项目以物理模拟揭示的深井巷道各深度处围岩单元加卸载应力路径与应力状态为切入点，建立破裂围岩单元主应力差峰后跌落幅度与其破碎程度的量化关系，提出新的破裂岩样制备技术，制备与松动圈内各深度处破裂围岩单元一一相对应的一系列破裂岩样；据破裂围岩应力状态设计不同应力路径，采用MTS和三轴流变仪对其瞬时与长期力学特性展开研究，建立其再破坏时的瞬时强度理论与流变力学模型；定义破裂围岩体积膨胀比以量化其扩容程度，建立该参数与瞬时强度理论和流变力学两模型中各指标间的函数，定量研究破裂围岩扩容程度对其力学参数影响规律，明晰深井巷道破裂围岩扩容特性，从扩容及流变角度揭示深井巷道破裂围岩大变形破坏机理；研究成果可为深井巷道围岩稳定控制新技术提供理论指导。

深井巷道围岩稳定已成为制约深部煤炭及其他矿产资源安全开采的瓶颈，其巷道围岩典型特点为初次破裂后长期变形不止，正确揭示其力学特性具有重要的理论及实际应用价值。项目紧紧围绕深井巷道破裂围岩力学特性及其大变形破坏机理关键科学问题开展研究。基于项目前期研究成果建立了深井巷道破裂围岩单元主应力差峰值后跌落幅度与其破碎程度的对应关系，提出了一种新的室内预制破裂岩样的技术，建立了室内破裂岩样与现场破裂围岩单元内在的联系；在此基础上，开展峰后破裂岩样三轴瞬时力学特性试验，获得了深井巷道破裂围岩单元不同围压条件下再次加载破坏瞬时强度及变形特征，并建立了破裂围岩再次加载瞬时破坏强度理论模型；同时，开展峰后破裂岩样单、三轴蠕变试验，获得了峰后破裂岩样单、三轴蠕变力学特性，重点分析了围压对其三轴蠕变特性的影响规律，并建立了峰后破裂损伤岩样单、三轴压缩蠕变本构模型；采用颗粒流分析软件模拟峰后破裂损伤岩样单轴蠕变，获得了峰后破裂损伤岩样轴向、横向与体积蠕变规律的异同，并选择破裂岩样卸载点处合适的参数作为定量表征其峰后破裂损伤程度的损伤因子，建立了损伤因子与各蠕变参数的函数，定量分析了围岩峰后损伤程度对其蠕变力学特性的影响规律。项目还开展了破裂岩样单轴再破坏瞬时力学特性、声发射与能耗特性研究，获得了破裂岩样再破坏时的强度、变形、声发射及能量特征，并建立了破裂岩样表面破裂面分布分形维数与其单轴压缩峰值强度及各能量指标间的定量函数，探讨了破裂岩样破裂程度对其声发射及能耗特性的影响规律、声发射与能耗特性两者间的内在联系。考虑深井巷道大多水文地质条件复杂，项目还开展了自然、饱水状态下粗砂岩岩样峰后循环加卸载试验，系统获得了粗砂岩自然、饱水状态下的应力-应变曲线特征、强度及变形参数损伤劣化规律、能量演化特性。在以上研究成果的基础上，揭示了深井巷道破裂围岩大变形破坏的机理。项目研究成果有望为深井巷道围岩稳定控制新技术的提出提供理论指导及依据。