Recently, with the completion of the final roof slab concrete pour, Dongsha Station on Guangzhou Metro Line 10 successfully topped out its main structure more than a month ahead of schedule, making it the first station on the entire line to be capped. As of the end of July, the civil engineering works for Line 10 (Xilang–Shipaiqiao) had reached 26% completion. Of the 14 stations, 1 has had its main structure topped out, 12 are under civil construction, and 1 is in preliminary preparation; of the 14 running tunnels, 2 are under civil construction and the rest are in preliminary preparation; and the Guanggang New Town depot is under civil construction.

Implementing Strict Early-Warning Monitoring to Meet Challenges of Complex Strata

Dongsha Station is located on the south side of Cuiyuan Road in Liwan District, running east-west along Cuiyuan Road, with the Dongxin Expressway entrance/exit to the west, the Guangzhou Ring Expressway to the south, Daganwei Station to the east, and Guanggang New Town Station to the west. The station is a two-level underground island-type station, approximately 326.5 meters long and 20.3 meters wide in the standard section, with the foundation pit excavated to a depth of about 19–23 meters.

Because a silt layer is present within the foundation pit area of Dongsha Station, reaching a maximum thickness of 13 meters, and there are also sand layers and strongly weathered silty mudstone with well-developed fissures and abundant groundwater, this posed great challenges to the excavation of the station foundation pit. During construction, the metro builders set up a total of 510 monitoring points to carry out real-time manual and automated monitoring of the horizontal displacement of the foundation pit walls, support axial forces, and groundwater levels, and promptly analyzed the monitoring data. At the same time, by optimizing the construction organization, shortening excavation step lengths, and adding temporary supports, they ensured the safety of the foundation pit.

Organizing Construction in Two Phases to Create Conditions for Tunnel Boring

Because the foundation pit in the western section of Dongsha Station is close to a resettlement housing project, with the nearest distance between the two pits less than 5 meters, simultaneous excavation of the pits would have involved enormous construction risks. In addition, the construction site for the western section of the station is narrow, making it difficult to deploy large mechanical equipment smoothly.

To ensure that the milestone tasks were completed on schedule, the metro builders decided to carry out the foundation pit excavation in two phases, concentrating resources to first complete the structural works for the 7 flow sections on the east side, which provided the conditions for the smooth launch of the line's first shield machine in October 2020. In mid-March this year, after on-site construction conditions were fully prepared, the metro builders quickly organized work on the remaining 8 flow sections on the west side.

In the face of the impact of the COVID-19 pandemic and Guangzhou's rainy season, the metro builders, while carrying out epidemic prevention and control work, ensured the health of construction workers through activities such as distributing cooling supplies. In response to the rainy season and typhoon weather, the construction site formulated special emergency plans, equipped sufficient emergency supplies, and organized regular safety drills to safeguard construction safety in all respects.