Based On The Settlement Of Optical Fiber Bragg Grating Sensor Research And Application

With the rapid development of science and technology, sustained growth ofeconomic and social progress, a variety of features of today’s engineering structureshave been experienced significant changes in materials, structure, technology, andbecoming more complex, automated, and long-term. In China, massive projects such aslarge-scale dams, bridges, highways, high-speed railway have been built constantly. Theeffective monitoring and early warning of such large and complex engineering structureis very important and urgent. Fiber optic sensing technology has its unique advantagesof anti-electromagnetic interference, corrosion resistance, good insulation, highsensitivity, electrical-passive, and may form into a large-scale sensor networks,Fiber-optic sensing has became a mature technology after more than30years’ research,and will play an important role in the field of geology health and safe monitoring.This topic is about a sensor of settlement based on fiber Bragg grating sensing, andis used for monitoring of high-speed rail foundation settlement. In this paper, we havecompleted the following work:1) Studied the basic principles of FBG and FBG sensing system, examined theapplications of FBG research in all fields, analyzed technical feasibility of FBG formeasuring foundation settlement, referred to the previously-proposed structures of FBGsensors for level or pressure measuring, and finally proposed a structure of the sensorbasis on FBG cantilever and the elastic metal diaphragm structure.2) Made engineering drawings of the structure of the sensor, manufactured thesensor, package the sensors, and built a laboratory test platform including opticalplatforms and mechanical-structure platform to test the performance of the sensor in allaspects,.3) Conducted a comprehensive test in sensor’s performance, including the range,linearity, repeatability, sensitivity and stability, Analyzed the impact of these factors onstructure through a large number of experiments, and made improvements on thestructure of sensor.4) Analyzed FBG the cross-sensitivity of strain and temperature of the FBG sensors, tested and verified a variety of methods of temperature compensation throughthe temperature experiment, and ultimately adapt a feasible structure that can meet theneeds for practical applications, with lower impact of the temperature on the settlementmeasurement.5) Improved the structure of the sensor according to the experimental results above,and packaged practical sensors under the consideration of a variety of engineeringproblems of practical applications, We also installed the sensor on a high-speed railfoundation in Chengdu, and gathered a lot of valuable experience in taking a stepforward to improve the sensor structure.