Research On Temperature Control Feedback Of Concrete Dam Based On Distributed Optical Fiber

The temperature of all concrete dams should be controlled during the construction period to reduce the temperature caused by hydration heat, control the highest temperature, reduce the temperature difference between internal and external or base and prevent cracks. It is the presuppositions to obtain inner temperature field information timely and correctly, comprehensively realize and control the temperature stress caused by temperature changes and prevent harmful cracks from forming and developing. Therefore, it is very necessary to monitor the temperature field in the constructing and operating periods of the bulk mass concrete dam. However, the temperature field monitoring is the weak link of dam safety monitoring for a long time. The optical fiber sensing technology has many advantages, such as the resistance to electromagnetic interference and corrosion, high-powered signal transmission bandwidth, real-time, dynamic and wide distribution, etc. It compensates the weakness of monitoring method. Therefore, it is the ideal technology and method for concrete dam temperature field monitoring.Based on the superiority of the distributed optical fiber sensing monitoring system, applied it to the monitoring temperature information, the related tests are designed to assist the construction and the rational use of monitoring data is discussed. The main contents included:1. Design Xiluodu Dam temperature monitoring system based on the distributed optical fiber sensing technology, arrange the overall measuring scheme, and discuss DTS data acquisition principle and data management and analysis process on the basis of the basic theory of optical fiber transmission. Provide reference for popularization and application of the optical fiber sensing technology in concrete dam temperature field monitoring.2. Properly display the advantage of optical fiber sensing technology, design related tests to monitor temperature gradient of the surface concrete under adverse weather conditions, such as solar radiation, temperature difference between day and night, air temperature pelter etc., as well as that around the cooling water, which can reflect the surface layer temperature condition of concrete more truthfully and comprehensively. Set up the computing temperature field and creeping temperature field of finite element mode simulation in comparison with actual measurement data, and feedback temperature control measures to improve the construction quality of concrete dam. 3. Taking the temperature monitoring data of distributed optical fiber as an example, including the statistics training of high and low temperature seasons, establish the highest temperature prediction model based on the BP neural network. Compare the highest temperature allowed with the highest temperature of the casting block by fast forecasting to judge the rationality of the established temperature control measures, which has an important significance for ensuring the quality of temperature control of casting concrete block. Finally, by the analysis of prediction model,determine these single factors'effect on the highest temperature of the pouring block, including pouring temperature, cooling water temperature, cooling water flow quantity, water pipe arrangement, air temperature, casting layer thickness, etc.