The Study On FGB Monitoring Technology Of High-speed Railway Continuous Curved Beam Bridge

The safety of the train running is the most important link of the high-speed rail-way transport. The characteristic of continuous curved beam bridge stress is complex, and its cross-section stress is much larger than straight beam bridge. Some factors make the bridge deform or climb and the state of high-speed railway more abomina-ble to bring dangerous, such as the geology of plateau is loose, greatly changed of environmental temperature, traction and vibration generated by high-speed train crossing the bridge. Therefore, it is necessary to monitor the structure and rail state of high-speed rail continuous curved beam bridge, early warning and prevent disas-ter occurrence.As an electric circuit of the driving force, high-speed rail has electro-magnetic interference, and open-air site exist shock, moisture and corrosion, conventional electric signal sensor could not meet the requirements of high-speed railway moni-toring. Compared with the conventional electric signal sensor, Fiber Bragg Grating (Fiber Bragg Grating FBG) sensor can resist the harsh environment of the installa-tion area because of a layer of corrosion-resistant coating on the surface of fiber. It is the absolute value of the measurement of the wavelength, no zero drift, and suit for long-term monitoring of the engineering structures, an optical fiber can measure a plurality of point to achieve distributed measurement. FBG sensor also has advan-tages of good stability and high sensitivity. Therefore, in this project, the project se-lects FBG to make sensors and use it to monitor the structural health of high-speed rail continuous curved beam bridge.The monitoring system uses strain, temperature, and displacement sensor. This paper describes the design, production, application of these sensors, and analysis and verification of results. This article works as follows.Firstly, this topic expounded the principle of fiber grating sensing technology, and then, Introduces the FBG sensor characteristics verified by experiments and also Introduces the basis for the application of fiber grating sensing technology which used in the high-speed rail continuous curved beam bridge monitoring system.Secondly, according to the characteristics of force, introduce three-dimensional monitoring method of the rail of curved beam ridge. Through the compare tests in-cluding bare grating and FBG strain gauge, the grating completely paste and vacant paste, different thickness of the cantilever piece, selecting the sensor design methods that make the results best match to the actual situation and resolve the problem of the temperature cross-sensitivity. Introduce their production process, packaging equip-ment and calibration methods.Thirdly, introduce the framework of the monitoring system and the layout of the detection point is classified according to the physical quantities, describes the instal-lation method of sensor and optical signal line laying and demodulation.Finally, lists relationship formula between displacement of demodulated grating wavelength and physical quantity, according to waveform diagram of data that had be processed, explains the detection result, give and verify the overall view of the various physical quantities detected when the temperature from low to high.