On January 11, inside the shield launching shaft on the banks of the Pearl River in Guangzhou, as the cutterhead of the 'Dadao Xianfeng' shield tunneling machine slowly rotated, the first shield machine for the Guangzhou Haizhu Bay Tunnel Project, surveyed and designed by China Railway Siyuan Survey and Design Group and constructed by China Railway 14th Bureau Group, was successfully launched. This marks a major breakthrough for the dual key projects of Guangdong Province and Guangzhou City, officially beginning the journey beneath the Pearl River.

The Haizhu Bay Tunnel Project runs through Haizhu District and Panyu District, with a total line length of 4.35 kilometers, including a shield section of 2,077 meters, a segment outer diameter of 14.5 meters, and a maximum burial depth of 50.64 meters. It passes beneath the Lijiao Waterway, Sanzhixiang Waterway, and Luoxi Island in the form of a twin-tube shield tunnel, making it the first super-large-diameter municipal shield tunnel in the Pearl River Basin.

Schematic diagram of shield machine tunneling

According to reports, this tunnel is one of the super-large shield tunnels with relatively difficult construction environments and construction challenges in China. It crosses long distances through argillaceous siltstone layers, withstands a maximum water and soil pressure of 5.2 bar, and has a minimum cover depth of 9.1 meters at the shield launching section, less than 0.7 times the tunnel diameter, making it an ultra-shallow cover launch and reception. The shield machine will pass through fractured zones twice, cross the Pearl River navigation channel twice, and traverse mudstone, argillaceous siltstone, and other strata over long distances, which can easily cause mud cake formation on the cutterhead and sluggish discharge in the excavation chamber, placing high demands on tunneling parameter control.

Operators are controlling the shield machine

In response to the engineering difficulties, China Railway 14th Bureau Group, drawing on its rich experience in shield construction across rivers and seas over many years, custom-built two slurry balance shield machines with an excavation diameter of 15.07 meters. These are also the largest-diameter shield machines in the Guangzhou area and are known as the 'First Shield of Guangzhou.' The 'Dadao Xianfeng' shield machine launched this time has been specifically researched and designed in terms of cutterhead tools, flushing systems, slurry circulation and muck discharge, and pressure and corrosion resistance. It is equipped with multiple innovative technologies, including a atmospheric cutterhead, telescopic main drive, telescopic cameras, VMT automatic measurement and monitoring system, and scraper wear detection, to address engineering risks under complex conditions.

Launch site of the 'Dadao Xianfeng' shield machine

It is reported that the Haizhu Bay Tunnel is the control project of the Guangzhou South Railway Station express corridor, built to the standard of an urban arterial road with a speed of 60 kilometers per hour and six lanes in both directions. It is planned to be completed and opened to traffic by the end of 2024. By then, it will take only 15 minutes to travel directly from central Guangzhou to South Railway Station, effectively alleviating the long-standing problems of detours and congestion, and is of great significance for promoting the construction of Guangzhou as a national central city and the interconnection of the Guangdong-Hong Kong-Macao Greater Bay Area.