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Abstract: The raise boring method is widely employed for shaft excavation at limestone quarries in Japan; however, excavation in fractured or weathered rock masses may cause serious troubles such as collapse of shaft walls, stoppage of excavation, and breakage of drilling tools. Hence, it is essential to understand the rock mass conditions around a shaft before or during excavation with the raise boring...
Abstract: The Horonobe Underground Research Laboratory (URL) in Hokkaido, Japan has been constructed in diatomaceous and siliceous mudstones, which are widespread in the areas along the Sea of Japan. It is essential to understand the mechanical and rheological characteristics of these rocks for the construction of underground structures and for the assessment of their long-term...