ABSTRACT
Hydraulic tunnels often have a second lining to sustain high internal water pressure (Li et al. 2010). This second lining is absent in most early stage shield tunnels, such as the Tokyo Bay transverse cross-sectional highway tunnel and the Tokyo municipal water pipeline with a history of 20 years until now (Zhao et al. 2004). In China, bilayer structures have become more popular due to rising concerns about single-layer prefabricated segment lining (Sun et al. 2011, Zhai et al. 2009, Li et al. 2014). However, this approach has not become popular in Chinese tunnel construction because there is a general lack of construction techniques and engineering experience necessary for such an undertaking.
