Distributed fiber optic sensors for tunnel monitoring:A state-of-the-art review

Distributed fiber optic sensors(DFOSs)possess the capability to measure strain and temperature variations over long distances,demonstrating outstanding potential for monitoring underground infrastructure.This study presents a state-of-the-art review of the DFOS applications for monitoring and assessing the deformation behavior of typical tunnel infrastructure,including bored tunnels,conventional tunnels,as well as immersed and cut-and-cover tunnels.DFOS systems based on Brillouin and Rayleigh scattering principles are both considered.When implementing DFOS monitoring,the fiber optic cable can be primarily installed along transverse and longitudinal directions to(1)measure distributed strains by continuously adhering the fiber to the structure’s surface or embedding it in the lining,or(2)measure point displacements by spot-anchoring it on the lining surface.There are four critical aspects of DFOS monitoring,including proper selection of the sensing fiber,selection of the measuring principle for the specific application,design of an effective sensor layout,and establishment of robust field sensor instrumentation.These four issues are comprehensively discussed,and practical suggestions are provided for the implementation of DFOS in tunnel infrastructure monitoring.

非开挖施工法安装管道位置的估计

在安装新管线时，对已有的采用非开挖方法安装的电缆和管道的定位资料并不是足够的充分。以往，不准确或遗漏登记、手工数据录入，都可能导致记录和实际位置之间的偏差。深度检查是位置检测的一大难题，尤其是在HDD工程中。 荷兰非开挖技术协会（NSTT）在过去几十年对非开挖安装精度进行了研究，包括影响管道精度的外部因素，以获得对已有的TT装置的位置精确的估计。本文综述了采用HDD、微型隧道、冲击锚、螺旋钻进及其他非开挖技术的安装精度，考虑土层条件及当下安装技术。同时，本文对此期间荷兰非开挖市场进行了介绍。