High Pressure Gas Pipeline Installation Inside a Long Length and Small Cross-Section Mountain Tunnel

The gas pipeline called “Mie-Shiga Pipeline” (60km total length, 610mm diameter, 7MPa maximum pressure, grade L450 (X65)) is under joint construction between Chubu Electric Power Co., Inc. and Osaka Gas Co., Ltd. This pipeline is planned to start supplying gas in 2014. Since the main part of our construction area is in a mountainous area called Suzuka Mountains, the mountain tunneling method is adopted in part of the mountainous area (about 7.5km in length) for gas pipeline installation to shorten the construction period. This paper discusses the design concept and the highly efficient technique for installing pipeline inside a long length and small cross-section mountain tunnel, as well as the application of an internal watertight wall, which is a task specific to the mountain tunnel.