Feasibility study for a multi-level pore water pressure monitoring system using FBG sensors

Takeuchi, Shinji; Kashiwai, Yoshio*; Hirata, Yoichi*; Yoshida, Yukimi*; Nishigaki, Makoto*

A multi-level groundwater monitoring system using FBG sensors has been developed for measuring pore water pressure and temperature in small diameter boreholes. The system consists of packer units, temperature and pressure sensing units, and optical fiber cable connecting units. The system with two measurement sections was established as a prototype for the feasibility study. A preliminary test was carried out for about 11 months in a borehole in the Tono area central Japan. The test data obtained in early period were unstable and periods of data loss occurred. Several improvements were implemented and subsequent results show the developed system is feasible for using in slim boreholes.