On August 19, at the construction site of the Pearl River Estuary Tunnel of the Shenzhen-Jiangmen Railway, the "Shenjiang No. 1" shield tunneling machine for China's deepest subsea tunnel, jointly built by CRCHI and China Railway 14th Bureau Group, successfully reached a depth of 106 meters below the seabed, completing its scheduled 3,590-meter tunneling task. This is the deepest underwater tunneling record for a Chinese shield machine and also the deepest subsea record reached by a Chinese high-speed railway shield tunnel.

The "Shenjiang No. 1" shield machine reaches 106 meters below the seabed

The Pearl River Estuary Tunnel, with a total length of 13.69 kilometers, is a key controlling project of the Shenzhen-Jiangmen Railway. The "Shenjiang No. 1" shield machine tunnels 3,590 meters from Dongguan toward Nansha, Guangzhou. During tunneling, the shield machine passed beneath multiple main navigation channels and traversed 13 types of strata and 5 types of composite geology, with full-face hard rock tunneling extending 2.75 kilometers, granite strength reaching up to 124.6 MPa, and continuous crossing of 17 fault zones and their branches. The complex hydrological and geological conditions of the section brought great difficulty to the project.

Schematic diagram of the tunnel longitudinal section

The lowest point of the tunnel's shield section lies 106 meters below the surface of the Pearl River Estuary, equivalent to bearing 10.6 kilograms of pressure on an area the size of a fingernail. There is no engineering experience or design standard under equivalent conditions in China for reference.

The "Shenjiang No. 1" shield machine rolls off the production line at CRCHI

To address the construction challenges, the "Shenjiang No. 1" shield machine is equipped with a series of intelligent systems, including a heavy-duty composite cutterhead with atmospheric and pressurized operation modes, a high-load main drive, and simultaneous single- and dual-fluid grouting. Its maximum pressure-bearing capacity reaches 12 bar, greatly improving its adaptability under ultra-high subsea water pressure conditions and ensuring continuous, stable, and safe tunneling in unfavorable geological sections with ultra-high water pressure, extremely large burial depth, and developed fissures.

The Shenzhen-Jiangmen Railway is located in the center of the Guangdong-Hong Kong-Macao Greater Bay Area and is an important component of the coastal corridor of the national "Eight Vertical and Eight Horizontal" high-speed railway network. Once completed and opened, it will help create a half-hour living circle and economic circle in the Greater Bay Area, and the Qianhai Free Trade Zone in Shenzhen and the Nansha Free Trade Zone in Guangzhou will achieve half-hour high-speed rail connectivity.