RESEARCH ON THE APPLICATION OF BOFDA MONITORING TECHNOLOGY TO THE CONSTRUCTION AND OPERATION OF SUZHOU METRO SHIELD TUNNEL

Shield tunnel is more and more widely used in underground traffic engineering and underground pipeline structures. Shield tunnel structure health monitoring is an important project to ensure the long-term health of the tunnel and the safety of the tunnel. BOFDA is a new technology of distributed optical fiber sensing developed in recent years and has begun to apply to monitoring the interior deformation of rock mass and soil mass. In this paper, according to the Suzhou metro shield tunnel structural health monitoring project, the distributed optical fiber sensing technology based on BOFDA is applied to the construction and operation of the shield tunnel structure's safety and health monitoring. The writer formulates detailed and feasible monitoring scheme, designs the reasonable optical fiber sensor and the supporting fixture to monitor the tunnel's circumferential convergence, longitudinal settlement and expansion joints and analyzes the tunnel's health status using the data reflecting the shield tunnel structure's safety and health condition got from the monitor. The monitoring results have shown that BOFDA can position and monitor the places of abnormal deformation, common tunnel leakage and segment dislocation precisely and effectively. Also, BOFDA has the technical advantages of distributed, long distance, corrosion resistance and high survival rate and it's a new and effective method to monitor the shield tunnel structure's safety and health status during the construction and operation period.