Development of optical fiber displacement sensor for bedrocks (The Second year)

Kashiwai, Yoshio*; Sanada, Hiroyuki; Matsui, Hiroya 

This work was performed by Taisei Kiso Sekkei Co., Ltd. under contract with Japan Atomic Energy Agency. The objective of this work is development of multiple stage optical fiber displacement sensors for the deformation monitoring of shafts and horizontal tunnels at the Phase 2 of Horonobe Underground Research Laboratory project. In previous year, the feasibility study was done for developing the multiple stage optical fiber displacement sensors of ten stages or more for the boreholes which diameter are 66 mm. Based on this feasibility study, two types of prototype for field measurement were developed and evaluated by laboratory tests. These prototypes were modified and field test equipments were developed which were consisted of 4 pieces of shallow part sensors and 2 pieces of deep part sensors.