The New Yung-Chung Tunnel, one segment of the EAST Railway Improvement Project, is a new tunnel excavated using the NATM construction method. The tunnel,with a length of 3,600 meters, connects the towns of Swu-Au and Tong-Au.
During excavation, a fault zone associated with a severe inflow was encountered,which in turn collapsed the tunnel. The highest water pressure, measured from the high-porous formation was 50 bar (50mpa), and the inflow rate was about 80 cubic meters per minute.Because of the extreme nature of the situation, it was impossibleto be handled using classic grouting methods, so Jines Co. introduced the hot bitumen grouting approach to facilitate excavation through this fault zone.The highly unstableformation was grouted while under a flow condition with hot bitumen before excavation.
It is the first time this grouting method had been need in Taiwan and only the second time in Asia.There were many difficulties to be resolved during this operation.The peculiarity and difficulty of the overall work has given it international visibility.
The whole grouting work was successful in June of 2002.