Research On Optical Fiber Grating Sensing Technology Applied To Deformation Monitoring Of High And Steep Slope

It has occurred frequently for natural disasters in complex slope regions along railway. Line interrupt caused by landslides and debris has become the main potential safety hazard. In order to guarantee the safety of railway and improve the transportation efficiency, it has been particularly important to develop a real-time monitoring system for the railway. A research on multi-parameter deformation monitoring technology has been carried out in this paper, including system construction of optical fiber grating sensor networks, development of the site monitoring sensors and tolerance extension of monitoring equipment.The main research and achievement are as follows:Firstly, based on the contrast and analysis of current domestic and international monitoring technology of slope, fiber Bragg grating sensing technology for high and steep slope was proposed. Through comparison of the parameters reflecting the state information of slope, axial force of anchor (effect of slope supporting), internal displacement of slope and variation of internal soil pressure field have been chosen as feature parameters. In order to obtain the complete monitoring information reflecting the safety state of slope, a monitoring system of slope deformation was established, based on fiber Bragg grating sensors technology, to realize real-time tracking of health state of slope.Secondly, according to the selected feature parameters, the relative technology researches were proposed, including the optimization of encapsulation parameters for fiber Bragg grating anchor to obtain ideal effective of strain transferring, research on optical fiber grating inclinometer to make it have the function of judgment of slide direction and temperature compensation, and the design of soil-pressure sensor to greatly reduce the additional effect caused by installation of soil pressure gauge through the introduction of dual L-shaped lever, making the sensor has obvious advantage in thickness to diameter ratio. At the same time, the characteristic of the proposed sensors were studied by experiments and performance of these sensors was obtained.Then, according to the characteristics of many monitoring parameters and large sensor array, a quasi distributed monitoring network was established based on light switch and combination of WDM and SDM. A light switch (1×4) was introduced to expand the demodulation equipment to16channels, realizing a sensing network of256FBGs. And the corresponding driver circuit was designed to realize a combination of serial port operation and remote operation, and finally to complete the cycle switching among different channels and specified channel switching.Finally, the main contents and conclusions in this thesis were summarized, and the contents for next study were pointed out.