变质岩区强应变带工程地质特性及隧道围岩稳定性分析

Engineering Geological Properties of High Strain Belts in Metamorphic Rock Areaand Stability Analysis of Tunnel Surrounding Rock

变质岩区强应变带构造挤压变形明显,变质分异现象清晰,工程性质差。通过对鸡公寨隧道湖蓝坡强应变带进行调查、测试及取样试验分析,结果表明:强应变带对岩性有明显的改造作用,片状矿物含量增高,岩石强度下降,软化系数0.36~0.50,岩体完整性系数0.25~0.46,属较破碎~破碎程度,呈薄片~碎片状岩体结构;构造残余应力明显,实测侧压力系数λ为1.3~1.9,以水平应力为主导。隧道围岩稳定性差,计算的围岩变形量远超规范允许值,且构造应力影响下的变形量远大于正常自重应力工况,在隧道设计、施工时需采取针对性的控制变形措施。

The strong strain zone in metamorphic rock area is characterized by obvious compression deformation,distinct metamorphism and differentiation,and poor engineering properties. Through the investigation,test and sampling test of the strong strain zone of the lake blue slope in the chakutan tunnel,the results show that the strong strain zone has an obvious effect on the lithology,the content of the sheet minerals is higher,the strength of the rock is decreased,the softening coefficient is 0. 36 ~ 0. 50,the integrity coefficient of the rock mass is 0. 25~ 0. 46,which is more broken and broken than broken. The structure of flake rock mass has obvious structural residual stress. The measured lateral pressure coefficient is 1. 3 ~ 1. 9,with horizontal stress as the leading factor. The stability of the tunnel surrounding rock is poor,the calculated deformation of surrounding rock is far beyond the standard allowable value,and the deformation amount under the influence of structural stress is far greater than the normal weight stress condition,and the corresponding control deformation measures should be taken in the design and construction of the tunnel.