Permanent Deformation and Temperature Monitoring of Subgrades Using Fiber Bragg Grating Sensing Technology

The hidden nature of subgrades makes the effective monitoring their deformation very difficult. This paper addresses this issue by proposing use fiber Bragg grating (FBG) sensing technology. Here, an FBG is encapsulated within a tube formed from polyvinyl chloride tube, and one end fixed perpendicular to concrete column, forming cantilever beam system. assessed according theoretical relationship between horizontal strain on embedded in vertical displacement beam. Then, variation wavelength light reflected temperature obtained basis calibration experiments. tubes are buried at proscribed depth below top surface subgrade, which facilitates subgrade different stages construction through collection data during periods, such as after embedding tubes, completion test road surface, period operation. proposed technology verified employing system monitor instantaneous maximum permanent under dynamic loads. results demonstrate that values 0.25 m 0.5 695.40 μm 574.02 μm, respectively, corresponding 53.00 41.54 respectively. sensor thereby provide reliable method for conducting long-term continuous, accurate, efficient monitoring.