深埋隧洞TBM开挖损伤区形成与演化过程的数字钻孔摄像观测与分析

TESTING ON FORMATION AND EVOLUTION OF TBM EXCAVATION DAMAGED ZONE IN DEEP-BURIED TUNNEL BASED ON DIGITAL PANORAMIC BOREHOLE CAMERA TECHNIQUE

以锦屏II级水电站3#引水隧洞为研究对象,通过事先开挖的平行于引水隧洞的2-1#试验支洞,利用数字钻孔摄像技术,对TBM掘进过程中围岩的开挖损伤区进行原位测试。基于对一系列不同时段的360°钻孔全景数字图像的综合分析,给出岩体的结构特性,得到隧洞开挖全过程中围岩裂隙的产生、发展和闭合的演化过程,分析该施工条件下的开挖损伤区范围、裂隙演化与TBM施工的关系,并探讨开挖损伤区的形成和演化机制。研究成果为现场支护设计、支护时机、围岩变形特性和地质资料分析提供直接依据。

It presents the in-situ test on excavation damaged zone（EDZ） evolution of TBM tunnel No.3 in Jinping II hydropower station using digital panoramic borehole camera.Firstly,through the pre-excavated diversion tunnel No.2-1,several boreholes vertical to sidewall of TBM tunnel No.3 are drilled for digital camera,and a series of digital images of borehole wall are obtained during the whole TBM driven time.Afterwards,the images will be digitally processed;geological structural surface and fractures of surrounding rock mass are also analyzed,which makes it possible for the whole procedure of cracks formation,development and close to be obtained.Finally,the depth of damage zone is recognized;the relationship between fractures evolution and TBM construction progress is given;and the mechanism of EDZ evolution is discussed as well.It will not only provide the direct data for geological exploration but also contribute greatly to support design and analysis of deformation behaviors of deep-buried tunnels.