Abstract: Long-distance water conveyance tunnel and other line projects will inevitably cross active fault zones, giving rise to the risk of structural deformation and tunnel instability. Reliable structural safety monitoring scheme is a necessary means to effectively monitor the safety state of tunnel and evaluate the adaptability of anti-fault measures. At present,there are few studies related to the structural safety monitoring system of tunnels crossing active fault zone. In view of this,a “five adaptations” principle of monitoring the safety of tunnel crossing active fault zone is put forward: the monitoring should adapt to 1) the current specifications or technical standards, 2) the motion characteristics of active fault zones, 3) the deformation law and failure characteristics of tunnel, 4) the anti-fault measures, and 5) the construction methods of tunnel. With the Xianglushan tunnel of Central Yunnan Water Diversion Project as a case study,the safety monitoring system and layout design based on the “five adaptations” are studied in line with the deformation and failure law under fault creep action. At the cross of Xianglushan tunnel and Lijiang-Jianchuan active fault,surrounding rock deformation and opening of joint should be considered as major monitoring items,and shear compression of joint and compressive strain of concrete should be taken as a basic monitoring content; the intersection area of the affected zone and the fault zone should be the key monitoring area; and dislocation meter, joint meter,strain gauge and pressure gauge should be selected as monitoring instruments. Moreover,the monitoring devices should be installed synchronously with the construction of monitored objects. Such a monitoring system serves as a useful idea for the safety monitoring layout design of tunnels crossing active fault zones

Key words: long distance tunnel, active fault zone, safety monitoring, layout design, Xianglushan Tunnel