Monitoring of Tidal Variation and Temperature Change-Induced Movements of an Immersed Tunnel Using Distributed Optical Fiber Sensors (DOFSs)

The short-term deformation behavior of immersed tunnels due to daily or monthly temperature changes and tidal variations is often not monitored but forms important input for a structural health assessment the tunnel. In this study, distributed optical fiber sensors (DOFSs) are used monitor (daily monthly) an Joint opening relative settlement differences between tunnel elements simultaneously at subhour intervals. Measurements show that variation in joint strongly correlated with change, gap has tendency open low temperatures close increasing temperatures. Simultaneously, entire section behaves more like rigid body moves upwards downwards periodically fluctuations river, observed vertical movement slightly less than one millimeter. tide also causes local tilting segments, differs winter summer, which implies (seasonal) temperature-induced deformations affect robustness loads. A soil-tunnel structure interaction analysis reveals cyclic driven by retardation wave deeper soil layers, can be captured coupled flow model. This study provides new insights into tunnels.