The blasting site of the tunnel entrance. Photo: China Railway Design Cooperation

 China is building the world's first high-speed train that can travel through a sea tunnel at a speed of 350 kilometers per hour in Shantou Bay, South China's Guangdong Province. 

The 163-kilometer-long railway, which includes a 9,781-meter-long tunnel, has officially entered the substantive construction stage, with an investment estimated to be at 11 billion yuan ($1.6 billion), the China Central Television reported Tuesday. 

According to the report, the tunnel will pass through 17 fault rupture zones in a magnitude-8 earthquake zone, of which eight are active faults, the first underwater tunnel of its kind anywhere in the world.

Most parts of the tunnel are located in high water pressure areas. As a result, construction personnel have to adopt measures to ensure that the tunnel structure is safe, waterproof and reliable, and that operating costs are controllable.

As the tunnel will be exposed to high-pressure seawater for a long time, its structure must be adapted to the strong corrosive environment while being able to withstand high water pressure penetration. The combined effect of the two factors makes the subsea tunnel environment more complicated.

Due to the tunnel's harsh environment, complex engineering geological and hydrogeological conditions, high construction risks and constraints of the construction period, workers will adopt a total of six construction methods in different sections. 

After completion, the railway will connect major cities in Guangdong, such as Guangzhou, Huizhou, Shanwei and Shantou, and help accelerate the urbanization along the route, form a new high-speed rail economic belt and boost the revitalization and development of eastern Guangdong. 

The project is part of a plan to narrow the development gap between eastern Guangdong and the Pearl River Delta region, and promote the balanced economic development of Guangdong.

Global Times