New technology of fiber leakage monitoring in long-distance water transfer channels in alpine and cold regions

In the seepage monitoring of long-distance water transfer channels, the traditional monitoring technology has obvious shortcomings. Based on the principles of Raman optical time domain reflection, a new type of seepage monitoring optical cableh is developed, and a distributed optical fiber Raman seepage monitoring technology which can be used in the long-distance transfer channels in cold regions is proposed. The laboratory tests are carried out for different field environments such as air, sand with different water content, pure water, etc. The results show that the new optical fiber cable can reflect the environmental characteristics under different environments, which confirms the feasibility of the optical fiber monitoring. By using the new fiber-optic leakage monitoring technology, field prototype tests are carried out in the main canal of North Xinjiang, and the pore pressure cells are installed in the fiber-optic buried place. The feasibility and measurement accuracy of the distributed fiber-optic leakage monitoring technology for the cannel leakage monitoring has been analyzed and verified. The distance between the optical fiber sampling points in the field measurement is 0.5 m, and the difference between the average value of optical fiber measurement and the pore water pressure gauge measurement is less than 0.5 m, which is within the theoretical range. It is shown that the optical fiber leakage monitoring technology is suitable for the field measurement conditions, and the accuracy, feasibility and reliability of its application in the long-distance water transfer channels incold regions are validated. © 2020, Editorial Office of Chinese Journal of Geotechnical Engineering. All right reserved.