中文摘要：

大型原位试验是研究复杂工程问题的重要手段。锦屏二级引水隧洞的建设过程中，在埋深1850 m深度针对TBM开挖的3#引水隧洞设计并实施原位试验。原位试验的内容包括：应力监测（空心包体和弦式）了解隧洞开挖过程中围岩应力状态的动态发展变化；声发射监测了解围岩应力调整过程中微破裂发生的位置和范围；松动圈测试确定围岩的开挖损伤深度；围岩变形监测（光纤光栅和多点位移计）了解隧洞的变形特征；数字钻孔摄像直观地观察围岩宏观破裂发展过程。本文是系列文章中的第一篇，介绍工程背景、试验的设计和试验区域地质结构的精细描述。

英文摘要：

The large scale in-situ test is an important method to solve complex engineering problems. During the construction of diversion tunnels at Jinping II hydropower station,an in-situ test program to monitor the realtime response of the surrounding rocks of the diversion tunnel excavated with TBM was designed and implemented. The contents of the in-situ test program include the stress measurement of rock mass with the rock stress meters of vibrating wire and CSIRO HI Cells to record the stress change in rock mass during tunneling,the acoustic emission monitoring to detect the crack initiation and propagation in rock mass during excavation,the sonic velocity measurement to determine the profile of excavation damage zone around tunnel,the displacement measurement with the multipoint displacement meters and fiber Bragg grating sensors to obtain the deformation of rock mass during tunneling,the digital photographing of borehole to observe the process of the macrocrack initiation. This article is the first of the series and introduce the background of the project,the designing of the in-situ test program,and the detailed geological models of the tested region.