Measurement of rock mass deformation around the closure test drift during groundwater recovery experiment at 500m depth of Mizunami Underground Research Laboratory

Kuwabara, Kazumichi*; Aoyagi, Yoshiaki; Ozaki, Yusuke  ; Matsui, Hiroya 

Authors developed a displacement meter using optical fiber sensor. The displacement meter can be set at any locations in a borehole and guarantee the measurement accuracy up to 5MPa. Total twelve displacement meters were installed in three boreholes to measure the rock mass displacement during groundwater recovery test. The measurement of the rock mass displacement was stated on March, 27, FY 2014. During the first and second groundwater recovery experiments, compressive displacements were observed close to the closure test drift wall. Magnitude of the measured displacements, except vicinity of test drift wall, was smaller than that of calculated under the assumption of it is an isotropic elastic material.