Software Implementation Of Geotechnical Engineering Strain Monitoring System Based On Fiber Bragg Grating

Geotechnical engineering is an important part of civil engineering, which is closely related with people's work and daily life. In recent years, with the accelerating pace of China's urbanization and the improvement of people's living standards, people are much more aware of environment-protecting. They want a more rational and friendly design of cities and towns. Meanwhile, due to frequent natural disasters in these years, people are paying more intension to Geotechnical engineering. They want their buildings to be strong enough to withstand disasters.Geotechnical monitoring plays a great part in geotechnical engineering. Generally, there are three aims in geotechnical monitoring:1) detecting the abnormal data and forecasting disasters to improve the safety level,2) measuring a variety of geotechnical parameters for scientific researches,3) providing reliable data for the following design of the project and the construction of information system.Serving a long time, occupying a great space, geotechnical engineering projects require high reliability and long-term stability, wide measurement range, and high adaptation to harsh environment. While the Fiber Bragg Grating sensors have following features:1) small volume, having negligible impact on the projects, 2) anti-electromagnetic interference, which means high stability and accuracy,3) measuring several spots within one single optical fiber, suitable for the large-scale distributed systems,4) high resistance to high and low temperature or corrosive environment. Thus, the Fiber Bragg Grating sensors have been widely used in many projects both at home and abroad.This article focuses on the software part of the geotechnical monitoring system. To be specific, there are data acquisition, database design and data monitoring in the design and implement of the software.The data acquisition part is written using the C++ language. The functions of data acquisition are building socket communicating with the Optical Sensing Interrogator SM125 to obtain the wavelength of fiber grating sensors, saving the data into MySQL database, controlling the optical switches to extend measurement range by time-sharing multiplexing. MySQL is choosed for the database for its compactness, various functions and high stability. The main function of the database is to design a variety of forms and store data to facilitate programs'inquiries. In this part, we mainly use two features of MySQL, the trigger and the task_scheduler. These two features make the database design more efficient, and the data processing more reliable.The data monitoring programs provides the user a friendly interface with rich functions. The data monitoring programs provide curves to show the real-time data. The alarm function shows data in different colors according to the alarm settings. The data storage part lets the user save the data as text file. The data query function stores the data in one recent month.And finally we make a CD-ROM, providing the installation wizard and help files. Then the user will quickly set up a monitoring platform for data monitoring, with the help of this CD.Geotechnical fiber strain monitoring system based on Fiber Bragg Grating, comes from a cooperation project between Optical Fiber Sensing Technology Research Center and the Geotechnical and Structure Engineering Research Center, which is designed for Xinjiang Malan Rock Laboratory. The system measures the strain caused by the pressure, temperature, displacement and other parameters in geotechnical projects. The system can be used for long-term monitoring in projects and experiments.The system has been delivered, running in good condition, and is often used in the Geotechnical and Structure Engineering Research Center for the model testing.