Key technologies for safety construction of mined subsea tunnels

by Dingli Zhang

As an important mode of cross-sea channeling, subsea tunnels have been widely used internationally, with over 40 foreign subsea tunnels constructed since the 1930s.

Their construction methods include drilling and blasting, immersed tube, and tunnel boring machine methods.

Of these, the drilling and blasting method is most commonly used owing to its many advantages.

For example, the drilling and blasting method has been used by Norway to build over 100 km of subsea tunnels and by Japan for building the famous Kanmon and Seikan subsea tunnels.

Thus, various foreign countries have successfully constructed subsea tunnels.

Key technologies for safety construction of mined subsea tunnels: However, China’s vast territories and geological conditions substantially vary, and the surrounding rock conditions are poor.

For example, weathered troughs (capsules) were encountered during the construction of the Xiamen Xiang’an Subsea Tunnel, fault and damage zones appeared during the construction of the Qingdao Jiaozhou Bay Subsea Tunnel,

and unfavorable geological conditions, such as karst structures, have been found where the Dalian Bay Subsea Tunnel is to be constructed—the key factor limiting its safe construction.

Key technologies for safety construction of mined subsea tunnels: As a tunnel engineering structure built below the seabed, subsea tunnels face two main challenges:

the prevention and control of water inrush during construction and water leakage and drainage control during operation.