Engineering Evaluation for Avalanche Risk Along the Tohoku Shinkansen Between Morioka and Hachinohe

Abstract

SYNOPSIS The authors discussed the existing method to evaluate the avalanche risk for Hokuriku Shinkansen, and specified its meanings from the engineering viewpoint. In the method, the avalanche risk was determined qualitatively as the product of starting risk and the risk to reach the site under consideration. However, the meaning of the calculated avalanche risk was not defined in qualitative terms. In order to take measures against the avalanche for Tohoku Shinkansen from Morioka to Hachinohe at the entrance of each mountain tunnel, the risk was first evaluated by using the same method as that for Hokuriku Shinkansen. Second, the resistance to the expected avalanche load was discussed with special attention paid to the existing structures, such as buffering works to minimize the effect of micro-pressure waves. Consequently, the avalanche resistance of the existing structures was found to be approximately 20kN/m2. Furthermore, avalanches with a load of not less than 20 kN/m2 may occur at slopes whose avalanche risk was greater than 70%.