主应力轴旋转条件下岩石破坏特征与强度准则

Excavations of deep tunnels induce stress adjustment in surrounding rocks. The stress redistribution consists of principal stresses value alteration and principal stress rotation (PSR). However, rock test research under PSR starts late. Failure mechanism and strength criteria are not enough. Therefore, the need for experimental and theoretical research is urgent. In this project, the rock failure character and strength criteria under PSR are set for the main line. The idea (from qualitative analysis to quantitative analysis, from macro to micro, from the analysis of phenomena to the study of mechanism) is performed in this project. Firstly, rock strength character under PSR and that without rotation is studied by rock hollow cylinder apparatus. Secondly, the evolution law of geometry parameters of macroscopic crack, rock mechanical parameters and AE parameters is analyzed. The microstructure of fracture and pore fractal dimension are also studied to reveal the mechanism of PSR effect on rock strength. Lastly, based on the test data, rock strength criterion is established considering the PSR. This research can provide theoretical basis for mechanical model and numerical calculation under PSR, and offer scientific support for optimal design and safety construction in deep tunnels.

深部巷道开挖诱发围岩应力调整，包括主应力大小变化和主应力轴旋转，实现主应力轴旋转的岩石力学试验起步较晚，主应力轴旋转条件下的破坏机理和强度准则研究仍不充分，迫切需要开展相关试验和理论研究。本项目以主应力轴旋转条件下岩石破坏特征与强度准则为研究主线，采用由定性→定量、由宏观→微观、由现象分析→机理研究的总体研究思路，通过一系列主应力轴不旋转和旋转条件下的岩石空心圆柱扭剪试验，对比研究主应力轴旋转条件下岩石的强度特性；通过分析宏观裂纹几何参数、岩石力学参数和声发射特征参数的演化规律，结合断口微观形态及孔隙分维数的研究，揭示主应力轴旋转对岩石强度的影响机理；基于试验数据，建立考虑主应力轴旋转的岩石强度准则。该问题的研究可以为主应力轴旋转条件下的力学模型和数值计算奠定理论基础，为深埋地下工程的优化设计和安全施工提供科学依据。

深部巷道开挖诱发围岩主应力大小变化和主应力轴旋转，主应力轴旋转条件下深部巷道围岩稳定控制是深部资源高效开采必须解决的难题。本项目以主应力轴旋转条件下岩石强度影响规律和机制为主线，采用由定性→定量、由宏观→微观、由现象分析→机理研究的总体研究思路，分析了深埋隧道开挖过程中围岩应力场和损伤演化规律，揭示了主应力轴影响范围与损伤演化的相关性，通过一系列主应力轴不旋转和旋转条件下的岩石空心圆柱扭剪试验，对比研究主应力轴旋转条件下岩石的强度特性，发现低应力水平下主应力轴旋转对强度起增强作用，高应力水平下主应力轴旋转对强度有弱化作用；分析了宏观裂纹几何参数、岩石力学参数演化规律，结合微观形态研究，揭示了主应力轴旋转对岩石强度的影响机理，随着应力水平增大，晶粒由压密到塑性位错、到穿晶破坏，脆性破坏特征越强。研究成果对于揭示复杂应力状态下围岩破坏机理、防治深部工程灾害具有重要意义。