An Investigation on mechanical properties of in-situ rock mass at the Horonobe Underground Research Laboratory

Niunoya, Sumio*; Aoyagi, Kazuhei  ; Fujita, Tomoo ; Shirase, Mitsuyasu*

In the Horonobe Underground Research Laboratory, rock mass classification and determination of mechanical properties of rock mass was conducted considering the effect of the density of fractures in the rock mass. In this paper, the authors report the mechanical properties of rock mass detected by plate loading tests and in situ shear tests in the 250 m and 350 m galleries. As a result, the failure criteria based on the result of in situ shear tests provides the most conservative value for the design of support pattern and assessment of stability of the gallery.