Abstract:

There are neither standards nor experience related to subsea tunnel construction in China Systematical study has been made on Jiaozhou Bay subsea tunnel in Qingdao in terms of project feasibility study, theoretical calculation analysis, indoor testing, field testing and engineering practice, and comparative analysis has been made on different seacrossing solutions Conclusions drawn are as follows: 1) Advantages of subsea tunnels have been summarized 2) Key design parameters of subsea tunnels, such as 25 m minimum rock overburden thickness for of 3lane subsea tunnels, 1 time tunnel diameter for clearance between twin tubes and 4% for maximum(longitudinal gradient, are obtained 3) Complex lining, multicenter ovalshaped tunnel crosssection and support parameters are obtained 4) The structural safety and minimum water discharge have been guaranteed by adopting the principle of “stopping the leaking water, with limited water discharging”, and the limited water discharging criteria is 04 m3/(d•m) 5) Technologies, such as controlled blasting, multiple anticorrosion rock bolt, C35 wet sprayed high performance concrete, and C50 durable concrete, are used in the durability design The predicted service life of the tunnel is over 120 years 6) The geological conditions and ground water conditions are predicted by means of advance water detection technology combined with geological sketching and geophysical prospecting 7) The construction safety has been guaranteed by adopting rapid and safe tunnel construction technologies, such as fullface excavation method or bench cut method, and collapse and water inflow prevention technologies

Key words: Jiaozhou Bay subsea tunnel, drilling and blasting method, limited discharging, durable concrete, advance water detection, collapse and water inflow prevention