Application Of A Distributed Optical Fiber Sensor For Road Subgrade Monitoring

The health condition of the subgrade affects the performance and the service life badly. This inclined more researches on the appearance and development of the early diseases. Currently, there is little method to monitoring the health condition of the road subgrade, especially need the way to monitoring continuously in large scale on the condition that it won't effect the construction and normal service. Recently, the optical fiber sensing technology has developed rapidly, with the outstanding material and sensing character, it provide a new way to monitoring the distribution and the change of the strain in the subgrade.In this paper, a continuously optical fiber sensor used to monitoring the deformation and damage is designed.It take advantage of the Brillouin scattering sensing technology (BOTDR/A)and the character that the armoringwire can bend freely when protecting the optical fiber sensor effectively. The sensor can provide measured data to analysis the mechanical property, the appearance and the development of the early disease in the subgrade.After tested the survivability and the effectiveness in the lab, the sensor is confirmed that the sensor can monitor the distribution of strain in the subgrade, and identify the crack. Analyzing and promoting the production process, the sensors are made in large scale, and applied in the ZT05 section of the He-Da expressway in Dunhua, Jilin province.The result of the experiment shows that the sensor can monitor the distribution and the change of the strain in the subgrade. By packaging the sensor with armoringwire, the sensor keep high suvivalbility and durability during embedded and its service life.The sensor can fulfill the demands to monitoring the health condition of the subgrade. The process and the results of this experiment provide some reference value to the research and design the structure of the subgrade, and provide some experiment to monitor the expressway subgrade.