The Monitoring of Segments Dislocation Deformation in Shield Tunnel Based on BOFDA

Shi Bin and Wang Xing

School of Earth Sciences and Engineering, Nanjing University, Nanjing, Jiangsu, China

Abstract. Shield tunnel is widely used in underground traffic engineering and underground pipeline structure, and the structure health monitoring is an important project to ensure the long-term health and safety of tunnels. Regarding to the deformation characteristics of shield tunnel, this paper presents a new method for the layout of sensing fiber based on BOFDA. By analyzing the plane geometry, the relationship between strain and deformation of segment dislocation was determined. The test accuracy and sensitivity of this method depends on fixed point distance. Laboratory test was conducted and the calculated results with this method had good consistency with the results by conventional dial meters. Using this long distance, high-density, high-accuracy and lost-cost health monitoring method, the safety of shield tunnel can be greatly ensured.

Keywords: Shield tunnel, Segment dislocation, BOFDA, Optical fiber sensing technology, Health monitoring

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