Construction site of Guangzhou Metro Line 18
Located in the alluvial plains of the Pearl River Delta, Guangzhou has an unique geological fault structure, known as the ‘’geological museum’. The metro project is spread all over this city and has 33 comprehensive hubs reaching 7 districts.
The region has both soft and hard rock; the silt layer has high water content and low bearing capacity, making it very easy for ground settlement. The TBMs had to cross the area with high safety risk and faced a lot of difficulty during construction.
As China’s first high-specification metro line with a speed of 160 km/h, Guangzhou Metro Lines 18/22 with a total length of 91.3 km, pass through Nansha, Panyu, Haizhu, Tianhe and Liwan districts. The total length of Line 18 is 62.7 km, and that of Line 22 is 31 km. The project is large in scale, of high standard, and with tight construction timelines. Since it is difficult to construct, new technologies and equipment have been applied, involving large investments.
Map of Guangzhou Metro Lines 18/22
China Railway Construction South China Construction Co. Ltd is the general contractor of the project, which was officially started on Nov 30, 2017. The first φ8.8 m TBM was launched on Aug 29, 2018.
On November 5, 2019, breakthrough of one TBMThe 52 TBMs of CRCHI successively crossed below rivers, operating metro lines, residential areas, and other risky places. The vertical clear distance between the working tunnel and the existing operating tunnel is only 5.5 meters, and there are 11 rivers with a width of more than 200 meters and a maximum length of 1600 meters.
To solve the engineering geological problems, CRCHI customized the fourth generation of φ8.8m TBM for the project. A number of technologies were developed and designed, such as the frozen cutter head, retractable main drive, cutters state monitoring mode, etc. A professional technical service team of 200 people was dispatched to guarantee rapid, efficient, safe, and environmentally protected construction of the tunnel, using 52 TBMs.
In the process of tunneling, the TBMs faced different ground layers such as soft rock, hard rock, with the soft and hard alternating. To solve the problem of tunnel collapse, the TBMs adopted the frozen cutter head technology, which can ‘freeze’ the soil layer into a shell type safety body, just like customizing a suitable safety helmet for the machine, which is more convenient for tunneling while stabilizing the surrounding geological environment.
Cross under existing operating metro lines
In extremely hard rock and high-risk environments, the telescopic main drive technology helps the cutter head to retreat, leaving more space for maintenance personnel to change cutters. At the same time, in cooperation with the cutter’s status monitoring mode, the status of the ‘teeth’ of the TBM is monitored in real time, and the best replacement time is selected, so as to minimize construction risks.
On September 28, 2021, the first section of Guangzhou Metro Line 18 was officially opened and put into operation. During the trial operation, it set the world’s fastest metro operation record of 176 km/h and achieved the goal of 30-minute direct access between the main city of Guangzhou and the Nansha Free Trade Zone.
The first 8.8 m TBM was launched on Aug 29, 2018
On March 31, 2022, the first section of Guangzhou Metro Line 22 was officially opened. The total mileage of Guangzhou Metro has exceeded 600 km, ranking third in the world. The first breakthrough section of Guangzhou Metro Line 18/22 reached 75 km.
The 52 TBMs of CRCHI that have completed the tunnel will be put into use in other projects after undergoing maintenance and refurbishment.