A dam health monitoring scheme based on distributed Brillouin

The application of distributed Brillouin optical fiber sensing technology in dam health monitoring is mainly studied in this paper. In the dam health monitoring system, the key technology is real-time deformation monitoring. Firstly, the principle of Brillouin optical time domain analysis (BOTDA) is introduced. A long-term on-line monitoring scheme of dam strain is proposed based on the distributed Brillouin sensing technology. The scheme includes cable layout and strain test. In the test, a 200m single-mode optical cable is selected. Firstly, the center frequency shift data of the whole optical cable is measured, when the displacement load is set to 0 mm, which is used as the test reference of strain variation. Then, the 2m length of the middle part of the optical cable is stretched to perform large amplitude tensile tests and shrinkage tests. The displacement loads are 2mm, 4mm, 6mm, 8mm and 10mm respectively. Next, small amplitude tensile tests and shrinkage tests are performed. The displacement load is 0.5mm, 1mm, 1.5mm and 2mm respectively. Analysis of test data shows that, the strain measurement range of the scheme can reach +/- 4500 mu epsilon, the resolution of the scheme can reach 20 mu epsilon. The results prove that the distributed fiber Brillouin sensor system can realize the long-term on-line distributed measurement of dam strain, which meets the requirements of the dam strain monitoring. It provides an effective means for dam health monitoring and protection, and a strong support for large-scale structural health monitoring with distributed Brillouin optical fiber sensing.