高应力开挖卸荷巷道宏观结构蠕变演化与失稳机理

Excavation unloading cause the macro-structure failure of the deep high-stress roadway, and the high stress leads to the special rheological instability of surrounding rock supporting layer, which are the hot spots of the deep roadway instability mechanism. However, the deep-seated problems such as the mechanic formation mechanism, the stability influence factors, the creep evolution characteristics and the rheological instability control method of the surrounding rock support layer are urgently solved. In this project, the research object is the macroscopic structural rheological instability of deep high stress unloading roadway. The integrated research methods include such as rock unloading test, numerical simulation technology, theoretical research and roadway model test and in-situ test.The mechanic formation mechanism of the "strong-weak-key" coupling bearing layer in deep roadway is revealed, the coupling mechanics model of the excavation and unloading surrounding rock under high stress is established. The time-space relationship between the stability of the "strong-weak-key" coupling support layer and the roadway fracture. The evolution law and rheological instability mechanism of the coupled support layer are analyzed. Based on the above research results, macro-structure rheological instability mechanism is grasped in kilometer deep roadway, and its structural instability support control countermeasures is scientifically designed.

开挖卸荷导致深部高应力巷道宏观结构性破坏，特别高应力围岩支承结构流变失稳，是目前深部巷道失稳机理研究的热点。但针对围岩支承层的力学形成机制、稳定性影响参数、蠕变演化特征和流变失稳控制方法等深层次问题亟待解决。本项目以深部高应力卸荷巷道宏观结构性流变失稳为研究对象，综合岩石卸荷试验、数值仿真技术、理论研究和巷道模型试验以及现场试验等研究方法，揭示深井巷道“强-弱-关键”耦合支承层力学形成机制，建立深部巷道开挖卸荷围岩耦合力学模型，掌握深部开挖卸荷巷道“强-弱-关键”耦合支撑层稳定性与巷道破坏之间时-空关系，分析耦合支撑层演化规律和蠕变失稳机理, 阐明千米深井巷道结构性蠕变失效机制，科学化设计巷道结构性失稳支护控制对策。

开挖卸荷导致深部高应力巷道宏观结构性破坏，特别高应力围岩支承结构流变失稳，是目前深部巷道失稳机理研究的热点。但针对围岩支承层的力学形成机制、稳定性影响参数、蠕变演化特征和流变失稳控制方法等深层次问题亟待解决。本项目以深部高应力卸荷巷道宏观结构性流变失稳为研究对象，综合岩石卸荷试验、数值仿真技术、理论研究和巷道模型试验以及现场试验等研究方法，揭示深井巷道“强-弱-关键”耦合支承层力学形成机制，建立深部巷道开挖卸荷围岩耦合力学模型，掌握深部开挖卸荷巷道“强-弱-关键”耦合支撑层稳定性与巷道破坏之间时-空关系，分析耦合支撑层演化规律和蠕变失稳机理, 阐明千米深井巷道结构性蠕变失效机制，科学化设计巷道结构性失稳支护控制对策。研究结果表明：1）多应力路径卸荷实验发现，岩石强度存在方向性差异，即沿巷道断面剪切和水平方向强度较弱，利用声发射监测高应力卸荷岩石流变失稳细观力学特性，发现卸荷岩石渐进性流变破坏规律，卸荷强度越大，稳压后岩石流变特性越明显，分级卸荷条件下，蠕变特征表现不明显；2）由围岩次生应力分布和强度劣化，提出了典型岩性巷道“强-弱-关键”耦合支承层划分方法和参考标准，可知硬岩和软岩支承层划分方法存在差异，结合围岩松动圈演化规律和内-主支承层结构，可知围岩耦合支承层与围岩松动圈中破碎带和裂隙带分布吻合；3）发现围岩“弱-关键”支承层、“弱-强”支承层转移，分别造成巷道塑性范围、塑性位移明显增大。“弱支承层”转移，对硬岩塑性位移和软岩的破裂区位移、软化区范围扩大影响明显；4）研究耦合支承层稳定性影响因素时，发现支护、埋深对硬岩承载稳定性影响较大，损伤因子和锚杆间排距对其“关键”支承层有影响。软岩巷道受预紧力、开挖“面效应”、内聚力软化模量的影响逐渐增大，通过减小软化模量在一定程度上限制耦合支承层转移、减小应力集中程度。