Research On The Health Monitoring Of Sluice Structures Based On Distributed Optical Fibers

Hydraulic structures had the properties of high costs, long construction periods, long service lifes, serious environment, etc. And the sluice was considered as a relatively common structure in hydraulic structures, which was an important part of the water infrastructures to promote the beneficial and abolish the harmful. According to statistics, at present, nearly half of the sluices in service were subjected to the different levels of damages in our country. And the service conditions of sluices are directly related to people's life and property safety. Therefore, it is very necessary to establish the health monitoring system of sluices to monitor the sluices' service condition in real-time and comprehensive way.In this paper, the two same reinforced concrete beam specimens were designed and constructed. And the resistance strain gauges and the distributed optical fiber sensors were respectively set at the surface of tensile steels, the internal and external of the concrete. According to the test results, the coefficients of brillouin temperature and strain of distributed optical fiber sensor were calibrated. Then temperature within the beam was measured, and the strains of steel and concrete were analyzed with using distributed optical fiber sensors. In addition, the cracking time of concrete was analysed. And the influence of the different paste materials of distributed optical fiber sensors to measure the concrete strain was studied. Finite element analysis by ABAQUS software was carried out. The deformation and steel strains obtained by finite element analysis were compared with the experimental results, and the finite element mode was verified. Then the sluice project in TaiZhou was simulated by the finite element software. Based on the results of finite element simulation for the sluice, the scheme of optical fiber sensors' layout in the health monitoring system of the sluice was promoted.The main conclusions are as follows:1. In terms of reinforcing steel strains, the strains measured by strain gauges were linearly consistent with the strain obtained by the optica fiber sensor in the elastic stage. And in plastic stage, the strain values measured by strain gauges were slightly higher than that of the optical fibers. In general, the concrete strains measured by optical fiber sensors and resistance strain gauges were almost the same.2. The cracking loads obtained by load-deflection curves of concrete beams were consistent with the cracking loads measured by distributed optical fiber sensors. The effectiveness of the optical fiber sensor in identifying concrete cracking time was available.3. The internal temperature change of the fresh concrete beam can be measured by using distributed optical fiber sensors.4. Compare the strain test results of the different paste ways of the optical fiber sensor, it was found that the optical fiber sensor pasted by different materials had a little influence on measuring the strain of concrete.5. The finite element analysis results of tested beams shown that the deformation of beams and steel strain were agreement with the experimental results, which was considered that the structural mechanics performance can be simulated by the finite element software. The finite element analysis' results of sluices indicated that strain distributions of the sluice were basically uniform. It was availiable to arrange optical fiber sensors according to the simulating result.