Mitigating large water ingresses into the New Yungchuen Tunnel, Taiwan

During the construction of New Yungchuen Tunnel, a major water inflow was encountered and the advance was abandoned. Further advances were attempted and again abandoned. Following detailed investigations, the problem area was determined as a very voided marble layer. The paper describes the use of hot bituminous grouting followed by cement and chemical grouting to both reduce the water inflow to acceptable volumes and pressures and also to reduce the convergence. In addition, the design of the tunnel was changed to include the construction of a larger circular tunnel through which the general horse-shoe shaped tunnel would subsequently pass.