Recently, the Guangzhou-Huadu Intercity Railway reached a double milestone: the right-line shield tunnel in the section from Baiyun City Center to Baifang Shield Shaft was successfully holed through, marking the breakthrough of the longest single-line section of the Guangzhou-Huadu Intercity Railway. At the same time, the right-line shield in the section from Jingbai Shield Shaft to Baiyun Dongping was launched. This is the 12th shield launched on the Guangzhou-Huadu Intercity Railway, and nearly half of the shields on the entire line have now been launched.

Longest section tunnel overcomes 6 major risk sources

The section from Baiyun City Center to Baifang Shield Shaft has a total length of about 3,497 meters, making it the longest section tunnel on the entire line. The shield was launched from the large-mileage end of Baiyun City Center Station and received at Baifang Shield Shaft, passing through strongly weathered argillaceous siltstone and moderately weathered argillaceous siltstone. The surrounding environment along the route is complex. The shield successively passed beneath 6 major risk sources, including factory buildings, building complexes, rivers, highways, overpressure gas pipelines, and the Liuxi River, crossing as many as 140 structures and buildings. In addition, the strata in the section tunnel have well-developed fissures and very abundant groundwater, making shield tunneling highly difficult and imposing high requirements on technical control during construction.

To this end, Guangzhou Metro, together with the Guangzhou-Huadu Intercity Railway general contracting department of China Railway Construction South China Construction and the builders of China Railway 11th Bureau Group, customized an earth pressure balance shield machine. The shield machine is equipped with a series of intelligent systems, including soil chamber visualization, tunnel cooling and temperature reduction equipment, automatic segment washing, and automatic shield tail clearance measurement. The shield machine also incorporates the "most powerful brain"—an intelligent shield system—which can achieve functions such as multi-terminal synchronization, intelligent monitoring, collaborative management, comprehensive analysis, risk warning, and decision support, enabling real-time control of shield tunneling conditions and improving shield construction safety.

Tunnel with maximum burial depth of 210 meters achieves shield launch

Recently, in the right-line shield tunnel of the section from Jingbai Shield Shaft to Baiyun Dongping, the roar of the shield cutterhead turning sounded as the third shield machine in this section, "Tiebing Guanghua No. 7," was successfully launched. The section is about 2.7 kilometers long. After launching from the large-mileage end of Jingbai No. 2 Shield Shaft, the shield advanced westward beneath Liupian Mountain and, after emerging from the mountain, reached Baiyun Dongping Station. The strata crossed by the section consist of fully weathered granite, with a maximum burial depth of 210 meters from the mountaintop to the tunnel bottom.

Constrained by issues such as the narrow construction site and the split launching of multiple shields, Guangzhou Metro, together with the Guangzhou-Huadu Intercity Railway general contracting department of China Railway Construction South China Construction and China Railway 15th Bureau Group, invited experts to demonstrate a split launching scheme for multiple shields at a small shaft opening using dual-mode shield machines. By extending a small belt conveyor for transfer and muck removal, they overcame the difficulties of muck hoisting and slow tunneling efficiency during split launching. By designing a vertical belt storage bin and combining a continuous belt conveyor with a vertical belt for continuous muck removal, they solved problems such as the small launching shaft opening and low muck removal efficiency.

As of now, 30% of the civil engineering works of the Guangzhou-Huadu Intercity Railway (Guangzhou East–Huadu Tiangui) has been completed. Civil engineering construction is underway at all 7 stations along the entire line; among the 7 sections, civil engineering construction is underway in 5 sections, and preliminary preparation is underway in 2; a total of 10 shield machines are currently tunneling. Civil engineering construction is underway at the Airport Depot.