On April 18, 2026, a report published by the French "Electronic Game Network" turned its attention to the mouth of the the Pearl River River. More than a hundred meters below the vast water surface, a "steel giant dragon" wearing "lion awakening" skin is advancing deeper into the sea at a speed of about 2 meters per day. While international media is still calculating economic data for the Greater Bay Area, Chinese engineers are using the cutterhead of shield tunneling machines to set a new world record in underwater rock formations.

Breaking the global record with 113 meters

The the Pearl River Estuary Tunnel is about 13.7 kilometers long, which is the "choke" project of Shenzhen Jiangjiang Railway. The domestically produced shield tunneling machine "Shenjiang No.1" has reached a depth of 113 meters, setting a world record for the deepest underwater high-speed railway shield tunnel construction, and continues to sprint towards the deepest point of 116 meters. The maximum water pressure in the tunnel reaches 1.06 megapascals, which is equivalent to withstanding over 10 kilograms of pressure per square centimeter, posing a limit test on the sealing and pressure bearing capacity of the equipment.

Cracking the problem of slag discharge with mud double pipes

How to deal with the "chewed" rock and soil is the key to excavating at a depth of over a hundred meters underwater. Shenjiang No.1 is equipped with a dual pipeline mud circulation system: one delivers dilute mud to the cutterhead for lubrication and cooling, while the other pumps thick mud containing slag to the ground treatment plant. After screening the slag, the mud is recycled. The tunnel adopts the "excavation and splicing" process, and the section with a diameter of over 13 meters is composed of 9 prefabricated pipe segments spliced together. The factory prefabrication and on-site assembly are seamlessly connected, greatly reducing the construction period. Keywords: Infrastructure Engineering News Network, high-speed rail shield tunnel, deepest underwater

Thirteen types of strata and six fault zones

The 'Shenjiang No.1' project needs to cross 13 types of strata, 5 types of composite geology, and 6 fault zones, among which the granite strength in the hard rock section of the entire section can reach up to 124.6 megapascals. In the control room, the staff adjusts the excavation parameters in real time through a multi angle monitoring and positioning system, and dynamically controls the flow and pressure of the mud entering and leaving. The main line of the Shenjiang Railway is 116 kilometers long and is a key section of the "Eight Verticals and Eight Horizontals" high-speed railway network along the coast. After completion, Shenzhen and Jiangmen can be connected within one hour. When this underwater tunnel is completed, another cross river artery will be added to the "urban agglomeration on the track" of the Greater Bay Area.Editor/Gao Xue