Experimental Study On Distributed Optical Fiber Sensor For Monitoring Leakage And Deformation In Dams

Dam leakage and deformation monitoring are the early warning important way which proceeds with early warning when the dam is in flood season. Distributed optical fiber sensor build on the basis of the temperature difference and strain identification, it has the advantages in embankment deformation and seepage which need the long distances and continuous monitoring. To the key problems of distributed optical fiber sensor in the monitoring application of the dam leakage and deformation launches theoretical analysis and experimental research of indoor and outdoor. This paper involves the mainly research contents as follows:(1)This paper reviews the detection methods of the dam internal leakage and deformation, leakage, settlement, collapsed, deformation and so on; According to the detection principle of distributed optical fiber sensing technology, this paper discusses the working mode and layout mode of distributed optical fiber sensing cable in the dam leakage and deformation monitoring.(2)This paper develops dam leakage and deformation monitoring and warning system specially applied for the water conservancy project, which bases on DiTeSt optical fiber sensing analyzer and established the function modules of the test data processing. For example, data file module is used to store the monitoring data and files; the trend prediction module adopts the moving average to do trend analysis according to the historical data; grading warning module proceeds real-time warning through compared with setting the threshold value.(3)Bending radius of optical fiber has an influence on temperature and strain characteristics of sensor cable in the practical application. Sensitivity of sensing cable and temperature and strain cross sensitivity of sensing cable are affected by factors; to certain cable for example, this paper specifically studies the regularities that different bending radiuses of optical fiber have an influence on temperature and strain of optical fiber and determines bending radius of sensor cable under on the specific construction conditions. Moreover, this paper designs a new bending radius adjust box of optical fiber in order to ensure curvature radius of optical fiber in practical process.(4)This paper launches experimental study of dam deformation and leakage for the setting up the system in the built outdoor experimental dam. It is in the experimental dam to arrange distributed optical fiber temperature and strain sensor respectively, and conduct preliminary analysis and processing by use of developed software, meanwhile, the conclusions are given. To further expand the application, this system conducts monitoring experiment of wall deformation for the pouring wall of up to30meters in the one of impervious wall construction. Experimental try will be contributed to be actual application of the monitoring vertical shaft structures.