Long-Distance and Continuous Horizontal Displacement Sensor of Deep Excavation Based on Distributed Optical Fiber Sensing

A long-distance displacement and continuous sensor based on distributed optical fiber sensing (DOFS) with the ability to measure the horizontal displacement of deep excavation was investigated herein. The feasibility and the accuracy were verified based on different numerical algorithms derived and finite element analysis (FEA). The evaluation of robustness under ambient noise and operational errors was conducted. The laboratory tests and on-site monitoring works were carried out. The experimental results confirm that the new optical frequency-domain reflection (OFDR)-based sensor can accurately measure the horizontal displacement field of the deep pit on the basis of 1-cm spatial resolution within 30-m soil depth. This allows to achieve real time and automated monitoring of the deep excavation, providing advanced safety monitoring of the excavation works.