Seite - 1426 - in Book of Full Papers - Symposium Hydro Engineering

The basic principle(Fig.1.) of DTS is to make use of the principle of optical time domain reflectometer (OTDR) and the temperature effect of Raman backscattering of fiber. The thermal expansion coefficient of optical fiber can modulate the phase of the laser to reflect the temperature information. Fig.1 Distributed optical fiber intelligent temperature monitoring system 2.2. FUNCTIONS AND FEATURES OF HARDWARE SYSTEM In order to obtain the real-time and accurate temperature data of concrete, Tsinghua university has developed the appropriate hardware system in the Wudongde construction site. The hardware system will transmit the temperature data to the cloud platform and the users can read the data from the platform conveniently. The specific functions are as follows: (1) the methods of system networking: RS485, 4G and WiFi. (2) the alarm function when fiber has been broken. (3) visible human-computer interface or mobile terminal interface. (4) no blind zone and continuance monitoring. Compared with the traditional temperature measurement by thermometers, optical fiber temperature measurement has a great deal of advantages: no electromagnetic interference, good temperature stability, long-distance monitoring, large amount of monitoring information, high degree of automation, real-time online monitoring. 2.3. SOFTWARE PLATFORM The software platform of Wudongde optical fiber temperature measurement system is developed independently by the Tsinghua university. The human- computer interface provides two methods. The first method is the WeChat software platform(Fig.2). The second method is the WEB client on PC. The two interfaces are based on the JavaScript programming language. laser Optical splitter Distributed optical fiber Stokes scattering Anti-Stokes scattering magnify magnify Cloud platforms PC/Mobile terminal Laser Driver Signal processor Alarm 1426