On January 4, 2024, with the completion of the last concrete pouring, the construction of the bottom plate of the middle air shaft structure in Jiangxinzhou of the Nanjing Metro Line 4 project was completed, realizing the smooth sealing of the main structure of the ultra-deep foundation pit in the floodplain area of the Yangtze River, and cracking the bottom of the Yangtze River 64The 5-meter construction safety risk has laid a solid foundation for the opening of Nanjing Metro Line 4.
The second phase of Nanjing Metro Line 4 is located in Jiangbei New District, Jianye District and Gulou District, starting from Pearl Spring Station in the west, walking along Puwu Road and Dingshan Street, passing through the Yangtze River, Qianzhou, Jiangxinzhou and Jiajiang in turn, and connecting to the first phase of Longjiang Station along Caochangmen Street after reaching the south bank. The line is about 10km long and is underground. Among them, the middle wind shaft of Jiangxinzhou is about 44 meters deep, which is the deepest foundation pit in the soft soil layer of the Nanjing Metro ProjectIt is a key project of China Railway Construction and China Railway 11th Bureau Group, and a high-risk project controlled by Nanjing Metro. 
Nanjing Metro Line 4 Jiangxinzhou ** wind shaft first steel cage hoisting was successfully hoisted Jiangxinzhou middle wind shaft is a five-storey underground three-column four-span box-shaped frame structure system, the length of the wind shaft is 1481 meter, width 333m 364 meters, about 44 meters deep, equivalent to 15 stories high. The wind well is adjacent to the Yangtze River and the Jiajiang River, surrounded by water on three sides, the groundwater is extremely abundant, and the water level of the Yangtze River is closely related, and the excavation range is dominated by the silt layer. The form of the enclosure structure is 65 meters deep and 1 thick5 m underground diaphragm wall +08 meters thick waterstop wall. The foundation pit adopts the semi-shun and semi-reverse method of construction, the upper three layers are open cut and the lower two layers are covered and excavated. 
In the construction of the underground diaphragm wall at the concrete pouring site, the project strictly controls the mud parameter interval of groove entry, groove formation and hole cleaning according to the construction requirements of different processes, so as to improve the mud wall protection effect and effectively solve the problem of soft flow geology in the Yangtze River floodplain area that is easy to collapse in the construction. The innovative use of 800 tons of crawler crane walking heavy-duty road reinforcement, slotting verticality control, mud index, reinforcement cage processing details and three-conduit concrete pouring and other new processes, to solve the problems of multi-lifting point ultra-deep and overweight underground diaphragm wall reinforcement cage hoisting, effectively reduce the risk of long-term hoisting operations. 
In the construction of ultra-deep and ultra-long concrete-filled steel tube columns, the project innovatively uses full-rotation, universal vertical platform, inclinometer, gravel belt backfill machine, underwater intelligent cylinder and other tooling equipment to quickly and efficiently realize the high-precision installation of ultra-deep and large-diameter concrete-filled steel tube columns in the Yangtze River floodplain area and the precise positioning of ultra-deep underwater embedded parts. In the construction of ultra-deep foundation pit in the Yangtze River floodplain strata, the construction team innovatively used the foundation pit automatic monitoring system to realize real-time monitoring and early warning of the deep horizontal displacement of the wall, the supporting axial force, the displacement of the soil outside the pit, and the water level outside the pit during the excavation of the foundation pit. 
The "main frame" of this wind shaft at the construction site of the project consists of 66 pieces with a depth of 645 meters, 1 thickIt is composed of a 5-meter, 180-ton reinforced concrete diaphragm wall. There is also a diaphragm wall with the same depth and thickness of 0The 8-meter water-stopping plain concrete wall is used to isolate the river and sand with a double barrier. The concrete-filled steel tube permanent structural column in the air shaft plays a vital role in the stability of the structure, and its verticality should reach one thousandth. With the help of innovative equipment such as universal vertical adjustment platform and inclinometer, the construction personnel followed the strict quality control process to achieve high-precision installation of ultra-deep and large-diameter concrete-filled steel tube columns, so that the actual verticality of the permanent structural columns reached 2/10,000, far exceeding the standard. 
The project construction site project also actively carries out technical management innovation, and holds mud index testing and underground diaphragm wall ultrasonic testing skills competitions to ensure that each technician can master the method of groove process control. Strengthen quality management training, organize on-site rebar workers to conduct practical competitions, find out the enthusiasm of on-site welders, form a healthy competition to catch up with learning, and improve the quality of on-site construction. Since the project department entered the site, it has high standards and strict requirements, and has held on-site observation meetings for many times, and the construction quality has been unanimously recognized by all units. 
Group photo of the projectThe construction of the second phase of Nanjing Metro Line 4 is conducive to the evacuation of the overly dense population in the central area, further expanding the urban spatial layout, and strongly supporting the realization of Nanjing's urban master plan. After completion and opening to traffic, it will further improve the rail transit backbone network in Jiangbei New Area, connect Jiangbei, Jiangnan, Xianlin and other regions, and also facilitate the transfer of passenger flow from north to south and east to west in Jiangbei area, improve the transportation service level of Jiangbei, and drive the rapid development of Jiangbei New Area. Publish a collection of dragon cards to share millions of cash