The construction project of Guangzhou Metro Line 18/22, as the largest metro investment in China, has attracted much attention. CRCHI has tailored 52 φ8.8m EPB/Slurry TBMs for the project, creating the world record of the largest TBM construction group applied in a single project, helping the construction of Guangzhou Metro and serving the Guangdong-Hong Kong-Macao Greater Bay Area.

Located in the alluvial plain of the Pearl River Delta, Guangzhou has an unique geological fault structure, being known as the ''geological museum'. The metro project is spread all over this city and 33 comprehensive hubs reach 7 districts. The soft rock and hard rock alternate. The silt layer has high water content and low bearing capacity, which is very easy to cause ground settlement. The equipment cross the area with high safety risk and great construction difficulty.

Map of Guangzhou Metro Lines 18/22

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, tight in construction period, high in standard, difficult in construction, wide in application of new technologies and large in equipment investment. China Railway Construction South China Construction Co., Ltd is the general contractor of the construction project. The project was officially started on Nov 30, 2017. The first φ8.8 m TBM was launched on Aug 29, 2018.

Construction site of Guangzhou Metro Line 18

The 52 TBMs of CRCHI successively cross under rivers, operating metro lines, residential area and other risky areas. 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 has customized the fourth generation of φ8.8m TBM for the project. A number of technologies were developed and designed, such as frozen cutter head, retractable main drive, cutters state monitoring mode. A professional technical service team of 200 people was dispatched to provide a strong guarantee for the rapid, efficient, safe and environmental protection construction of the tunnel with the world's largest 52 TBMs group.

In the process of tunneling, the TBM is faced with different ground layers such as soft rock, hard rock and soft & hard alternating. To solve the problem of tunnel collapse, the TBM adopts 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.

In extremely hard rock and high-risk environments, the telescopic main drive technology can help the cutter head to retreat, leaving more space for maintenance personnel to change cutters. At the same time, in cooperation with the cutters 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 the construction risk.

On November 5, 2019, breakthrough of one TBM

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. On March 31, 2022, the first section of Guangzhou Metro Line 22 was officially opened, making the total mileage of Guangzhou Metro has exceeded 600 kilometers, ranking the third in the world. The first breakthrough section of Guangzhou Metro Line 18/22 reach 75 km.

The 52 TBMs of CRCHI have all completed the tunnel and will be put into other projects after maintenance and refurbishment.