隧洞围岩应力开挖扰动特征与规律研究

Stress Disturbance Characteristics and Law Research of Surrounding Rock During Tunnel Excavation

以锦屏二级水电站引水隧洞为研究实例,对引水隧洞掌子面推进过程中的围岩应力状态和主应力轴变化规律进行了研究.分别通过地质数据处理中的"极点图"表现方法和断裂力学应力状态参数应力三维度,来描述主应力轴的旋转变化规律和应力状态变化规律.研究表明,随着掌子面推进,掌子面前方的围岩主应力轴方向调整具有一定共性,均表现为最大、最小主应力以一定交角指向临空面,中间主应力近似平行临空面,隧洞围岩应力状态由三轴受压状态转化至双轴压缩或单轴压缩状态.最后,根据应力三维度随开挖进尺的变化关系和空间分布特征,将隧洞围岩开挖应力扰动区分为强应力扰动区和弱应力扰动区,分析了各扰动区的应力扰动特征和规律,相关结论与认识对于围岩开挖扰动研究具有较大的理论和工程意义.

Regarding the diversion tunnel of Jinping secondary hydropower station as the research instance, the surrounding rock stress state and variation of principal stress axes were studied in the advancing process of tunnel face of diversion tunnel. Respectively through the pole diagram performance of geological data processing method and stress triaxiality of tress state parameter of fracture mechanics, describe the rotation variation of principal stress axes and variation of stress state.Study shows that as tunnel face advances, the reorientation of principal stress axes of surrounding rock in front of tunnel face has some generality, which is that maximum and minimum principal stress both point to free face with a certain angle and intermediate principal stress is approximate parallel to free face, as well, stress state of tunnel surrounding rock is transformed from triaxial compression to biaxial compression or uniaxial compression. Finally, based on the relation between stress triaxiality and excavation footage and spatial distribution characteristics of stress triaxiality, the stress disturbed zone of surrounding rock during tunnel excavation is divided into strong stress and weak stress disturbed zones. On this basis, authors analyze stress disturbance characteristics and law of each disturbed zone, the related conclusions and understanding can provide theoretical and engineering significance.