Xiangzhou District, Zhuhai

Work on the Maliuzhou Tunnel linking Hengqin Island with downtown Zhuhai is well under way and the eastern and western routes will be broken through in September. Its western route was connected on Dec 7.

The tunnel is the third traffic passage linking downtown Zhuhai and Hengqin New Area following Hengqin Bridge and Second Hengqin Bridge. When the two bridges have to be closed during severe weather, the subsea Maliuzhou Tunnel will be the only traffic line connecting Hengqin directly with the Chinese mainland, explained an executive of the contractor.

Maliuzhou Tunnel in progress [Photo by Li Jianshu / Zhuhai Daily]

Construction commenced in July 2014 with total investment of 2.54 billion yuan ($369 million). The 2,800+ m route across the Maliuzhou Waterway is circular with dual six double-barreled lanes 3.5 m wide each. The new infrastructure is China’s first subsea tunnel with the application of a super-large diameter shield in compound stratum.

According to the project’s deputy manager, Hu Tianbao, three major difficulties concerned riprap, rock stratum, and drainage. The Hengqin New Area Administrative Committee therefore invited an expert panel led by Qian Qihu, an academician of the Chinese Academy of Engineering, to address the problems. They reached a consensus that preprocessing should be adopted in terms of cut blasting, excavation of riprap, and opening of the chamber to clean the drainage board, which should solve the problems of both the western and eastern routes.

Hu added that the subsea tunnel was far more difficult than a subway tunnel. Shield tunneling machines for subway tunnels have a diameter of 6 m to 8 m with almost the same burial depth, while Maliuzhou Tunnel’s earth/water pressure balance shield is in diameter of 14.93 m, the largest in South China. The burial depth of the double barrels also reaches 14.93 m, according to Hu.

The large-scale municipal project is invested by the Hengqin New Area Administrative Committee, constructed by Shanghai Tunnel Engineering Co Ltd (STEC), and managed by Zhuhai Da Hengqin Port Industrial Co Ltd.