Model Test Of Leakage Monitoring Based On Distributed Optical Fiber Temperature Sensing Technology

The leakage monitoring is very important to guarantee the security of dams and other water retaining structure. The leakage monitoring includes not only whether the leakages have happened, but also locating the leakage zones accurately, the paths and the speed of leakages. Due to the differences of geological conditions and terrains, the structure of dams is complicated and the size is quite huge. As a result, the leakage monitoring has been a tough task to proceed. The method of distributed optical fiber temperature sensing system (DTS) to monitor leakage assigns a new direction for leakage monitoring. It makes it possible to accurately monitor the leakage of the whole dam body. Taking a panoramic view of the domestic and foreign research status, the usage of the distributed optical fiber sensors is just starting. However, its advantages in leakage monitoring are obvious. At present, most of researches in leakage monitoring, which are based on the distributed optical fiber temperature sensing, still stay in the stage of quantitative analysis. That is judging the leakage zones by monitoring the temperature anomaly. The monitoring of leakage speed is still at the experimental stage. There are many problems that required to be solved urgently in monitoring. Based on the research of the distributed optical fiber temperature theory to monitor leakages, On the basis of monitoring theory, we designed and constructed the model test of leakage to simulate all kinds of conditions and test models.The main content that researched in this article includes:(1)The main methods of leakage monitoring are summarized systemically. And the use of these methods and the advantages and disadvantages are summarized as well. The author focuses on the comparison of the fiber bragg grating temperature sensing system and the distributed optical fiber temperature sensing system.(2)Except test model that was well designed, the author designed the test programs against the purpose and content of this test. The author argued the procedure in detail, and introduced and tested the equipment and characteristic of medium etc.(3)The author writes a program to extract and organize the data. The range of heating power is determined through the test of preparation.(4)The author researched the impact of temperature rise due to different mediums. Through the analysis the author found that: in different mediums the temperature which was monitored increased with the heating power's increase. But the ranges were not the same, the extent with a descending order is: rocks > clay > sand.(5)The author researched the impact of temperature rise due to moisture content. From the research we can see: the fiber's temperature decreased when the moisture content increased in mediums. In the case of high moisture content and low heating power, the curve of temperature rise was more obvious. Therefore, higher heating power was preferred in the test.(6)The author researched the impact of temperature rise due to heat conductivity. With the research we can know: the temperature decreased when the heat conductivity increased. However, they were not a strict linear relationship.(7)The author stimulated the leakage of dams with models and researched the impact of fiber's temperature rise due to leakage speed. The extent of fiber's temperature rise decreased with the leakage speed increased. The temperature decreased most in clay, the sand take the second place and rocks had the least impact. This is determined by the inner structure of mediums and the characteristic of themselves.