Development of an integrated pore water pressure and ground subsidence profile monitoring system
|關鍵字:||地層下陷;孔隙水壓;光纖監測;Ground subsidence;pore water pressure;fiber optic sensor|
Optical fiber sensors have the advantages of being small, light-weight, immune to short circuit or electromagnetic interference, durable, good for long distance data transmission (over 10km) and multiple sensors can be connected to a single optical fiber. This research intends to make use of these advantages, develop an optical fiber Bragg grating (FBG) extensometer that is capable of monitoring ground subsidence. When coupled with FBG piezometers, the integrated sensor system can be deployed to monitor pore-water and ground subsidence profile simultaneously, in a single borehole. An observation well was established at Guon-Fu elementary school, in Hu-Wei Township of Yun-Lin County, where the developed sensor system was installed and soil samples taken for physical property tests. The field installation was completed in the end of April, 2012. The FBG sensor readings were taken on a monthly basis. A continuous 24 hour and 72hour reading were also taken for the analysis of daily variations of pore-water pressure and ground subsidence profiles. This thesis describes the development and improvement of the FBG sensor system, and the standard procedure for sensor system installation according to experiences gained in this research. The effectiveness of the integrated FBG sensor system is discussed.