Measurement of the deformation behavior of the rock mass in the 350 m gallery in the Horonobe Underground Research Laboratory

Sakurai, Akitaka; Aoyagi, Kazuhei  ; Fujita, Tomoo ; Motoshima, Takayuki*

In a high level radioactive waste (HLW) disposal project, it is necessary to investigate the long-term behavior of thermos-hydro-mechanical-chemical of the rock mass around the engineered barrier system of the HLW waste for the safety assessment of the disposal system. In addition, long-term stability of the rock mass around the galleries are required for the disposal facility. Considering these backgrounds, the authors measure the deformation behavior of the vertical pit drilled on the floor of the 350 m gallery in the Horonobe Underground Research Laboratory. In situ measurements of the deformation of the pit and rock mass around the pit was conducted to apply to the assessment of the long-term deformation behavior. The authors describe the drilling of the vertical pit, geological observation, specification of the measurement instrument, measurement method, and result of the measurement in this report.