Distributed Fiber Optic Monitoring and Stability Analysis of a Model Slope under Surcharge Loading

ZHU Hong-Hu 1, SHI Bin 1*, ZHANG Jie 2, YAN Jun-Fan 1, ZHANG Cheng-Cheng 1

1 School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China

2 Department of Geotechnical Engineering, Tongji University, Shanghai 200092, China

*Corresponding author

Abstract: In the discipline of geotechnical engineering, fiber optic sensor based distributed monitoring has played an increasingly important role over the past few decades. Comparing with conventional sensors, fiber optic sensors have a variety of exclusive advantages, such as smaller size, higher precision, and better corrosion resistance. These innovative monitoring technologies have been successfully applied for performance monitoring of geo-structures and early warning of potential geo-hazards in China. In order to investigate their ability to monitor slope stability problems, a medium-sized model of soil nailed slope has been constructed in laboratory. The fully distributed Brillouin optical time-domain analysis (BOTDA) sensing technology was employed to measure the horizontal strain distributions inside the model slope. During model construction, a specially designed strain sensing fiber was buried in the soil mass. Afterward, the surcharge loading was applied on the slope crest in stages using hydraulic jacks and a reaction frame. During testing, a NBX-6050 BOTDA sensing interrogator was used to collect the fiber optic sensing data. The test results have been analyzed in detail, which shows that the fiber optic sensors can capture the progressive deformation and failure pattern of the model slope. The limit equilibrium analyses were also conducted to obtain the factors of safety of the slope under different surface loading. It is found that the characteristic maximum strains can reflect the stability of the model slope and an empirical relationship was obtained. This study verified the effectiveness of the distributed BOTDA sensing technology in performance monitoring of slope.

Keywords: Slope stability; Geotechnical monitoring; Fiber optic sensor; Distributed strain sensing; Brillouin optical time-domain analysis (BOTDA); Model test


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