STUDY ON WATERPROOF AND DRAINAGE PRINCIPLES OF XIAMEN SUBSEA TUNNEL

Subsea tunnel is different from land tunnel with abundant water,high water pressure and without automatic drainage. These lead to more serious leakage problems,which are difficult to be dealt with comparison to land tunnel. Rationality and reliability of the waterproof and drainage system are the key factors for a successful subsea tunnel and the main parts controlling operation cost. The determination of waterproof and drainage principles is the basis for design of reasonable waterproof and drainage system. Based on the data of the existing subsea tunnels,the critical groundwater level is put up to determine waterproof and drainage principles. The water discharge and water pressure on lining with hidden pipe drainage system are calculated by numerical method for Xiamen subsea tunnel,and the feasibility of installation of drainage system is studied from point of view of economical efficiency during operation. The principle that blockage is dominant and drainage is limited is put forward for Xiamen subsea tunnel. Based on this,the reasonable waterproof and drainage system is brought forward and has been applied to this project. As the first systematic study for the first subsea tunnel with drill and blast method in China,the research method is a reference for other subsea tunnels.