Recently, at the construction site of Shield Shaft No. 2 in the section from Jingxi Road to Baiyun Dongping of the Guangzhou-Huadu Intercity Railway, the completion of the final segment ring assembly marked the successful verification of the vertical mechanical shaft construction technology applied for the first time in China's rail transit construction field, laying a foundation for its promotion and application in this field.

Shield Shaft No. 2 in the Jing-Bai section is located in the plot on the west side of Tonghe Road, Baiyun District, and adopts open-cut shaft plus vertical mechanical shaft construction, in which the shaft boring machine excavated to a depth of 27 meters. The geology is complex, with three lithologies distributed in an intersecting manner, and the site is adjacent to dense building clusters and municipal roads, making construction difficult and high-risk. To solve this "stumbling block" problem, China Railway 15th Bureau, as a main force and explorer in rail transit construction, actively communicated with the construction and design units. They boldly tried new approaches, adopting vertical mechanical shaft construction technology and making clever use of new technologies, new processes, new materials, and new equipment. Working with CRCHI to "prescribe the right remedy," they developed the "Future" caisson-type shaft boring machine. This shaft boring machine has a diameter of 14.2 meters and weighs about 120 tons. It uses a cutting-type cutter head for direct excavation without the need for retaining structures, and has the advantages of a short preparation period, good safety, fast construction speed, and investment savings.

Since there are still no national, industry, or local standards for the mechanical shaft construction process, domestic equipment and construction technology remain in the initial exploratory stage. To ensure smooth excavation of the mechanical shaft, before construction they conducted repeated "rehearsals" of the new technology through extensive preliminary research, theoretical model calculations, technical demonstrations, and other methods.

Since the launch of the right-line shaft on December 20, 2022, they overcame problems such as wear and replacement of roller picks, blockage of drum grates requiring repair welding, and retention and difficult discharge of large stones inside the shaft, avoiding risks such as over-excavation of the shaft, foundation pit collapse, settlement of surrounding strata, and damage to the cutter head of the shaft boring machine. By improving the equipment's adaptability to strata and construction efficiency, they finally completed the right-line shaft excavation on March 8, 2023, lasting 78 days. To further improve the application and research of the new technology, they immediately held a technical summary meeting and invited authoritative industry experts to optimize and improve the construction technology. In the left-line shaft construction, the efficiency of the boring machine was significantly improved, and the excavation task was completed in only 34 days, saving nearly 60% of the time.

It is reported that the Guangzhou-Huadu Intercity Railway is the first intercity railway led by Guangzhou, and after completion it will achieve 30-minute access between Guangzhou's peripheral urban centers and the city center. In the future, it will also realize through-running or cross-line operation with the metro and intercity railways, forming an important north-south passenger flow corridor on the west bank of the Greater Bay Area. It is of great significance for building a "Greater Bay Area on rails" and promoting regional urban integration.

Jing-Bai section shaft construction site