dws-tec-hzmb-bridge-submerge-tunnel-island-770px-1The underground tunnel section of the Hong Kong-Zhuhai-Macao bridge was completed on 7 July, marking the end of construction of the main structure for the world's longest and deepest underwater tunnel.

The tunnel is 6,7 km long and is 48 meters under water in the Pearl River Estuary. The tunnel is part of a 22.9 km long sea bridge that now connects the three cities. The bridge part was already completed in September last year.

The Dutch-based Tunnel Engineering Consultant (TEC) provided the HZMB Administrative Authority with international specialist support regarding the design, construction, and operation & maintenance of the tunnel and the artificial islands.

dws-tec-hzmb-bridge-submerge-tunnel-ceremony-350px Ceremony on 7 July marked the completion of the tunnel section of the 22.9 km long combined bridge & tunnel sea crossing of the Pearl River Estuary.

Immersed tunnel
The tunnel is comprised of 33 immersed sections linked by one 6,500-metric-ton butt joint in the middle.

The main reasons for selecting the immersed tunnel option - over a bored tunnel option - were the poor geotechnical conditions with related risks and the wide double 3 lane road layout that had to be accommodated with an adequate operational safety level.

Transition from bridge to tunnel
Two artificial islands mark the transition from the bridge sections of the link and entrances to the immersed tunnel underneath the main navigational channel.

Construction of these islands posed a significant challenge to the project in terms of foundation engineering, hurricane protection and construction scheduling.

An innovative solution for fast construction was developed. Large diameter steel cylinders were vibrated into the soft soils forming a temporary sea defense and a confined area for reclaiming the core with sand.

dws-tec-hzmb-bridge-submerge-tunnel-350pxTransport and immersion of one of the 33 tunnel elements.

About TEC
Tunnel Engineering Consultants (TEC) is a permanent joint venture partnership between leading international engineering consultants Royal HaskoningDHV and Witteveen+Bos.

Since the start in 1988, the partnership has delivered design and construction solutions to the Øresund Link between Denmark and Sweden, the Busan Geoje Link in South Korea, and the 32 km connection between Hong Kong, Zhuhai and Macao in China.

This news item is based on the original publication on the website of TEC.

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Country: China

More information
Tunnel Engineering Consultants (TEC)
Amersfoort, the Netherlands
+31 88 348 25 40

Completion ceremony of the 6.7 km tunnel section of the Hong Kong-Zhuhai-Macao bridge on 7 July.