2014 年 10 巻 1 号 p. 5-14
A method for measurement of stress change is suggested to monitor rock stress using a borehole. The two-dimensional state of stress change in a plane perpendicular to the axis of a borehole drilled within a rock mass can be measured by this method, which is named the Cross-sectional Borehole Deformation Method (CBDM). In this paper, the theory of the CBDM is firstly described, as well as the prototype instrument and theoretical procedure for correcting eccentric positioning of the instrument in the borehole.Then the estimation of the stress change is demonstrated in a laboratory experiment, using a granite plate with a borehole. Finally, applying the CBDM to measured stress change around an underground cavern during and after excavation, the changes of rock stress distribution around the cavern is shown. It makes clear that stress change in the immediate rock mass of the cavern can be estimated by the CBDM and that the CBDM is available for measuring rock stress change.
