Development of in situ stress estimation method based on the measured convergence and geological observations

Kamemura, Katsumi*; Aoyagi, Kazuhei  ; Nago, Makito*; Sugawara, Kentaro*

In situ stress state is very important for the design of deep underground facility of high-level radioactive waste disposal repository. This study establishes a practical and effective method for estimating in situ stress state based on the measured convergence and detailed geological observations during gallery excavation. The convergence was measured in various directions of the loop gallery at 350m depth of the Horonobe URL; this allows determination of the stress state corresponding to the rock mass behavior in 120m 200m area. In situ stress state estimated by the back analysis considering existing faults and fractures showed a good agreement with that of estimated from hydraulic fracturing method.