On December 25, after four months of hard work by the builders of China Railway Tunnel Bureau, the “Dawan area code” shield machine applied to the Pearl River Estuary tunnel of Shenjiang railway, the deepest subsea tunnel in China, successfully started in Nansha, Guangzhou, officially opening the construction challenge of crossing the Pearl River Estuary 115 meters underwater.
Shenjiang railway is an important part of the coastal channel, the main channel of the national “eight vertical and eight horizontal” high-speed railway. It is a major transportation infrastructure supporting the construction of Guangdong, Hong Kong and Macao Dawan district. The main line of the line is 116 km long and passes through five cities of Shenzhen, Guangzhou, Dongguan, Zhongshan and Jiangmen. As the line needs to cross the Pearl River Estuary between Guangzhou and Dongguan, the geology is very complex, and the design scheme has been compared and selected for several times, and finally the highway railway dual-purpose bridge is changed into a tunnel.
The Pearl River Estuary tunnel is a control project of the whole line of Shenzhen Jiang railway. Map provided by correspondent
The Pearl River Estuary tunnel is a control project for the whole line of Shenzhen Jiang railway, with a total length of 13.69 km and a design speed of 250 km per hour. China Railway Tunnel Bureau has undertaken the construction task of 9175m. The maximum underwater buried depth is 115m, which is the deepest record of underwater tunnel in China. The maximum water pressure is 1.06 MPa, equivalent to 10.6kg per square centimeter. The strength exceeds 10 Standard atmospheres, which is the highest in the world.
There is no engineering experience, shield equipment and design standard with the same conditions for reference in China. The maximum length of single head shield tunneling is 2930m, which means that the shield machine must replace the worn tools in the unfavorable geological section with ultra-high water pressure, which is very risky and difficult.
“Dawan area code” shield machine is a super large diameter shield machine jointly built by China Railway Tunnel Bureau and China railway equipment for the Pearl River Estuary tunnel. The excavation diameter reaches 13.32 meters, the total length is 133 meters, and the total weight is about 3900 tons. Combined with the characteristics of engineering geology, the development team is equipped with innovative technologies such as small knife spacing atmospheric pressure composite cutter head, retractable main drive, ultra-high pressure automatic compensation, four circuit pressure maintaining, air cushion direct row tunneling system, etc. The sealing technology of the main bearing with the maximum pressure of 12bar in China is also applied, which keeps improving and strictly controls the quality, providing a strong guarantee for the safe and efficient construction of the tunnel.
Schematic diagram of Pearl River tunnel crossing.
Since the “Dawan district code” shield machine went offline in Foshan, Guangdong Province in August 2021, the construction team of China Railway Tunnel Bureau has formulated a detailed disassembly, transportation and assembly scheme, scientifically organized on-site multi process construction, and quickly realized the shield departure on the premise of ensuring safety.
Yu Baolin, party secretary and chairman of China Railway Tunnel Bureau, introduced that before the reform and opening up, the total mileage of traffic tunnels in China was about 1395 kilometers. Since the establishment of the Tunnel Engineering Bureau of the Ministry of Railways in October 1978, the enterprise has built 3640 tunnels of all kinds, equivalent to 10000 kilometers of single track. As the starting point of a new journey of thousands of miles, the Pearl River mouth tunnel of Shenzhen Jiangkou railway will provide unique samples and valuable experience for the world subsea tunnel engineering technology, and carry the dream of China’s tunnel marching into the deep-sea era.
The site of shield launching ceremony. Map provided by correspondent
It is understood that the Pearl River mouth tunnel of Shenjiang railway was officially started in July 2020. After the completion of Shenjiang railway, it will be connected with Jiangxi Shenzhen high-speed railway at Xili station of Shenzhen hub, Hangzhou Shenzhen railway and Guangzhou Shenzhen Hong Kong high-speed railway at Shenzhen North Station, Guangzhou Shenzhen No. 2 high-speed railway under planning at Shenzhen Airport Co.Ltd(000089) station, Guangzhou Zhuhai intercity railway at Zhongshan station, and Jiangmen railway at Jiangmen station, so as to further open up the coastal high-speed railway channel, Help build a half-hour living circle and economic circle in Guangdong, Hong Kong and Macao Bay area, radiate and drive the coordinated development of eastern and western Guangdong and the Pearl River Delta.
(Southern Metropolis Daily)
