In the golden October, good news keeps pouring in. The Guangzhou-Songshan double-line section of Phase I of the Dongguan Rail Transit Line 1 project and the left line of the Yuanshan Station–Longxing Station section of Shenzhen Urban Rail Transit Line 16 have been successfully completed. Three tunnel boring machines (TBMs) from CRCHI (China Railway Construction Heavy Industry) involved in the construction emerged from the tunnels during the same period, boosting rail transit construction in South China.

Double-line breakthrough in the Guangzhou-Songshan section of Phase I of the Dongguan Rail Transit Line 1 project

Recently, the "Guanlong No. 6" and "Guanlong No. 7" earth pressure balance TBMs, jointly developed by CRCHI and China Railway 14th Bureau Group, helped achieve the double-line breakthrough of the Guang(dong Medical University Station)–Song(shan Lake Station) section of Phase I of the Dongguan Rail Transit Line 1 project. At this point, all three sections of this contract package have been successfully completed, laying a solid foundation for the line to open to traffic on schedule.

Breakthrough site of the section

The left-line TBM section of the Guangzhou-Songshan section is 832 meters long, and the right-line TBM section is 825 meters long. The section passes beneath an urban expressway with heavy pedestrian and vehicle traffic, and the underground pipelines are laid out in a complex manner. A 110kV power pipeline, a rainwater box culvert, and others cross the tunnel, while multiple bedrock protrusions exist within the tunnel envelope, making construction highly difficult.

To adapt to the complex geology and surrounding environment of the section, CRCHI, together with China Railway 14th Bureau Group, carried out a series of targeted designs for the TBM, such as a reinforced cutterhead, a high-performance main drive system, a high-precision earth pressure balance control system, a high-pressure-resistant main drive sealing system, and a multi-level grouting system, greatly improving the TBM's geological adaptability. At the same time, to improve the tunnel working environment and meet human-centered requirements, the TBM was also equipped with a tunnel ventilation and cooling system.

Equipment off the production line

Supported by the high-performance design of the TBM and through the construction team's careful organization and coordination and optimization of construction techniques, "Guanlong No. 6" achieved a best daily advance of 20 rings (30 meters) and a best monthly advance of 256 rings (384 meters), setting a new TBM excavation record for the entire Dongguan Rail Transit Line 1. In just 80 days, it completed the breakthrough of nearly 900 meters of the double-line section on the same day with "zero cutter changes."

Left-line breakthrough of the Yuanshan Station–Longxing Station section of Shenzhen Urban Rail Transit Line 16

Recently, the cutterhead of the "Xing'an No. 1" earth pressure balance TBM, jointly developed by CRCHI and China Railway 14th Bureau Group, broke through the soil, marking the successful completion of the left line of the Yuanshan Station–Longxing Station section of Shenzhen Urban Rail Transit Line 16.

Breakthrough site of the left line of the Yuanshan Station–Longxing Station section of Shenzhen Urban Rail Transit Line 16

The second phase of Shenzhen Urban Rail Transit Line 16 has a total length of 9.46 kilometers. The left line of the Longxing–Yuanshan section is 1,060.8 meters long, and the section mainly passes through silty clay, gravelly cohesive soil, soil-like/blocky strongly weathered sandstone, and slightly weathered marble; karst is developed in the section, and the tunnel envelope locally passes through karst caves and strata with uneven hardness. The geological conditions of the left line of the Longxing–Yuanshan section can easily cause problems such as TBM deviation, jamming, ground settlement, segment damage, and cutterhead damage.

To overcome the above difficulties, CRCHI, together with China Railway 14th Bureau Group, carried out targeted designs for the equipment. By adopting a six-spoke heavy-duty cutterhead, the structural strength and rigidity of the cutterhead are ensured, and its adaptability to strata with uneven hardness is improved. At the same time, a small cutter spacing design is adopted to improve the cutterhead's rock-breaking capability.

"Xing'an No. 1" TBM off the production line

As a key rail transit project in the Guangdong-Hong Kong-Macao Greater Bay Area, the second phase of Shenzhen Urban Rail Transit Line 16 is a rail trunk line for realizing the southward expansion of Universiade New Town in Longgang Central City. Once the project is completed, it will accelerate the flow and efficient allocation of resources in the Bay Area and promote the integrated high-quality development of the Bay Area.