Deformation in roof rock was measured on an experimental tunnel in Matsumine mine. Two extensometers were installed in bore-holes drilled from an opening 15 meters above the experimental tunnel before its excavation. Therefore, the vertical displacement in the roof rock can be measured not only after, but also before the face passes under the measuring section.
The vertical displacement in roof rock consists of elastic part immediately after the blasting and time-dependent inelastic part. The inelastic displacement is considerably larger than elastic one. Total displacement and inelastic displacement in roof rock between two blastings increases with time following the power law, and the inelastic displacement rate decreases also following the power law. Through the measurement of such deformation behavior, it became clear that the rock mass around the experimental tunnel in Matsumine mine behaves as a visco-elastic body; a great part of the displacement is due to viscous or time-dependent behavior.
