Flexible Encapsulation Method Of Optical Fiber Sensor For Road Structure Monitoring

The development of the economy has prompted the rapid increase of mileage on domestic freeway, which also brings up safety questions and high concerns on the road structure. When the track, crack and pot hole occur, not being tested in time, it will cause more and more such phenomenon that the road structures are massively destroyed under the impact of rain and vehicle load. With the increasing demand of testing tool with high precision and function on the road structure of freeway, this article researches a new type of flexible and packaging fiber optical sensor on the basis of theory of fiber optical sensor and demand of long-term safety monitoring on the multilayer road structure. And it has been put into practice at the testing road section. Actually, it is a safety monitoring system reflecting the road structure that we massively underlay each structure layer with sensors on the condition of not influencing its integrality, do long-term monitoring, collect and analyze the data, finally get the preliminary result of research of fiber optical sensor.The study of this subject is designed to the road structure with many medium layers. Through this kind of studying, not only it can ensure a large span of detection, but also it could provide a sensory system with a high-accurancy date for some local key-points in order to monitor the stress status in internal structure in any time and provide the related data to analysis the road deterioration and its causes. During the test, it is found that the variation of stresses could happen as road layers under the influence of external temperature and road load. By analyzing the date changes, it can be detected out the deformation and crack happening in the internal structure and then would be easier to monitor in the end. In order to guarantee the experimental accuracy, by conducting the indoor bending test of small beam, it could be found that the Fiber Bragg Grating Sensor has a clear recognition to transformation especially the crack which also proves the applicability of the sensory in the road.This paper mainly studies the designing concept of the monitor system and a method of flexible packaging technology. This monitor system combines FBG and BOTDA (BOTDR) in one which can ensure high-accurancy detection in a large or local range. The packaging technology overcomes the difficulties working is the adverse working conditions and at the same time detect the validity of this technology by indoor and outdoor experiments. The result shows that this kind of sensory has a high survival rate (>75%), and also is suitable for detecting the road structure effectively for a long time.