三峡库区高陡危岩软弱基座力学特性研究——以望霞危岩炭质页岩基座为例

Research on soft foundation mechanical properties of unstable rock on steep slope in Three Gorges Reservoir area:A case study in Wangxia

对三峡库区巫峡望霞危岩软弱基座炭质页岩样品进行X射线衍射与SEM扫描电镜分析,结果表明矿物成分中蒙脱石、云母、绿泥石含量较高,这些层状结构硅酸盐矿物具有高吸水性与易滑性特点;岩溶区地表碱性环境下蒙脱石和云母向绿泥石转化,岩石抗剪强度低,易发生滑动导致危岩体失稳。使用RMT-150C岩石力学试验系统进行不同围压下炭质页岩三轴压缩试验,通过一元线性回归分析方法获取了炭质页岩强度参数粘结力c=200 k Pa、内摩擦角φ=29.9°;对岩石屈服强度、峰值强度、残余强度与围压数据进行回归分析获得线性控制方程,建立了炭质页岩应力-应变全过程曲线,结果表现出压密、弹性变形、应变软化、塑性流动4个阶段。

The results of X-Ray diffraction and SEM analysis on the carbonaceous shale of soft foundation of the Wangxia unstable rock in WU gorge indicates that the mineral content such as montmorillonite,mica and chlorite is high. These layered silicates show high water absorption and sliding characteristics. Under alkaline ground surface in karst area,the montmorillonite and mica are converted to chlorite,decreasing the shear strength of rock. Therefore,it leads to the whole rock body sliding down along the direction of the major structural surface. According to the triaxial compression test result of carbonaceous shale under different confining pressure by use of the RMT-150 C mechanical testing system,the cohesive force is about 200 k Pa and internal friction angle is about 29. 9° are obtained by Linear regression method. The linear governing equation of the yield strength,peak strength,residual strength and confining pressure is developed based on regression analysis method. The complete stress-strain curveof carbonaceous shale is established and divided into compaction phase,elastic deformation phase,strain softening phase as well as plastic flow phase.