On January 16, with the completion of pouring for the last diaphragm wall panel Q1-19, the No. 3 ventilation shaft of Section JCXSG-3 (West Section) of the Airport Link Line project, constructed by Shanghai Tunnel Engineering Co., Ltd. (STEC), finished all underground diaphragm wall construction. This laid a solid foundation for subsequent foundation pit excavation and structural backfilling.

The main foundation pit of the No. 3 ventilation shaft is 30.6m long and 25.67m wide, with an excavation depth of 33.701m; there are 26 diaphragm wall panels in total, with a depth of 60m. The first diaphragm wall panel was poured on August 1, 2020, and all diaphragm wall construction was completed on January 16, 2021, 15 days ahead of the construction schedule.

The construction site of the No. 3 ventilation shaft is narrow, with the enclosed area only 75m x 60m, and the reinforcement cage formwork was set up in two sections. The 220kV high-voltage line crossing above the foundation pit is only 20m above the ground; the property owner requires a vertical safety distance of 6m, so the maximum construction clearance cannot exceed 14m. To solve the difficulties of constructing 60m-deep diaphragm walls, two targeted measures were proposed: for the trenching equipment, modified low-clearance 7.5m trench cutters and 9m milling cutters were selected; for the lifting equipment, the height of the 275t main crane + 100t auxiliary crane was restricted, and all equipment was provided with lightning protection and grounding treatment, eliminating equipment overheight and over-limit issues at the source. The reinforcement cage was lifted in 9 sections to ensure the safety of low-clearance lifting. At the same time, the site is close to a residential area. To prevent construction noise from affecting residents, an 8m-high sound barrier was used to enclose the construction fence, night work was reduced, and the construction impact was minimized as much as possible.