A Study of risk assessment of rapid inrush of water into the underground facility at the Mizunami Underground Research Laboratory project, 1; Development of risk assessment methodology of water inrush using discrete fracture network model

Motoshima, Takayuki*; Ijiri, Yuji*; Onoe, Hironori ; Saegusa, Hiromitsu; Otsu, Hiroyasu*

Since the groundwater inflow into a tunnel has a large impact on a construction cost and a schedule. It is important to estimate the influences of groundwater inflow on the cost and schedule quantitatively based on prior information about hydrogeological properties. In this study, the hydrogeological structure of fractured granite distributed at the Mizunami Underground Research Laboratory was modeled by a stochastic Discrete Fracture Network, and the risk of water inrush is evaluated probabilistically based on the model. The effects of parameter value uncertainties derived from field data on the risk of water inrush were also discussed.