On June 15, at the section between Luomashi Station and Sichuan Provincial Gymnasium Station of Phase III of Chengdu Rail Transit Line 18, excavation of the wind shaft foundation pit reached the bottom at a depth of 52.5 meters, once again setting a new record for ultra-deep foundation pit excavation in Chengdu rail transit!

One end of the Luomashi–Sichuan Provincial Gymnasium section of Line 18 Phase III connects to Luomashi Station, the deepest station under construction in Chengdu. After leaving the station, the section runs parallel beneath the existing operating Line 1, so its average burial depth is greater than that of ordinary lines. To meet the functional requirements of long-distance section fire evacuation, tunnel ventilation, and section drainage, a 52.5-meter-deep wind shaft was created. This wind shaft foundation pit, equivalent in depth to a 17-story underground building, is 2–3 times the depth of an ordinary metro foundation pit. It is not only the deepest in Chengdu and Sichuan Province, but also rare in domestic metro construction.

The wind shaft foundation pit in the Luomashi–Sichuan Provincial Gymnasium section is adjacent to the Jinjiang River, with a straight-line distance of only about 50 meters. Groundwater is abundant, making dewatering and drainage the number-one challenge for the builders. After repeated study, the project construction personnel proposed a "combination of prevention and drainage" approach to solve the problem of perched water at the rock interface. They installed dewatering wells inside and outside the pit, cast pile-sheet walls at the interface between sand and gravel and mudstone, reserved drainage holes between piles, and drained and lowered the water table through various means such as open pumping, creating favorable conditions for smooth excavation of the foundation pit.

The retaining piles and uplift piles around the wind shaft foundation pit in the Luomashi–Sichuan Provincial Gymnasium section are more than 60 meters long. Establishing an effective support system is key to ensuring construction safety. From top to bottom, the project construction personnel successively installed seven levels of construction walings and support structures of different materials to fully ensure the stability and safety of the soil mass. At the same time, because the wind shaft construction space is narrow and mucking is difficult, the construction personnel also innovatively adopted telescopic-arm excavators and cranes for mucking to carry out layered excavation, smoothly advancing the project construction.

It is reported that Phase III of the Chengdu Rail Transit Line 18 project has a total length of about 15 kilometers. It is an urban rail express line running north-south through the central urban area, and is an extension of Phases I and II of Line 18 toward the central urban area and the Chengdu Tianfu International Airport North cluster, connecting transportation hubs such as Chengdu Station, Chengdu South Railway Station, and Chengdu Tianfu International Airport.