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This morning
Nanjing Metro Line 4 Phase II
Cross-river shield machine “New Journey”
It starts from the wind shaft in the middle of Jiangxinzhou
Excavate to the north bank of the Yangtze River
The construction of the river crossing section kicked off
The second phase of the project of Metro Line 4 starts from Pearl Spring East Station, walks along Puwu Road and Dingshan Street Road, crosses the Yangtze River, Qianzhou, Jiangxinzhou and Jiajiang in turn, and connects to Longjiang Station, the starting point of the first phase of the project, with a total length of about 10 kilometers, all of which are underground lines, with 6 stations, including 2 transfer stations.
It is understood that the total length of the shield section line from the middle wind shaft to the Jiangbei Civic Center Station is 3,062 meters, which is designed for a single hole and two lines, and is constructed by a slurry balance shield machine. When the shield machine started in Jiangxinzhou, the top covering thickness was about 26.8 meters thick, and when crossing the Yangtze River, the deepest covering thickness was 55.35 meters, which was the deepest subway line across the Yangtze River Delta region.
The slurry balance shield machine named “New Journey”, with an excavation diameter of 11.64 meters, a total weight of 2,100 tons and a total length of 120 meters, adopts the “synchronous injection of double liquid slurry technology” for the first application of the construction of the domestic cross-river subway tunnel, which can effectively control the floating of segments, ensure the safety and efficiency of construction, and improve the quality of forming tunnels.
The work of the slurry balance shield is mainly to promote the excavation and segment assembly. On the cutterhead at the front of the shield machine, there are two passages in and out, and in the excavation process, the excavation face injects the mud prepared in advance into the soil that is about to be excavated through pressure to form a mud film; At the same time as the mud film is formed, the cutterhead continuously rotates to excavate the soil, and mixes the excavated soil with the mud to form a high concentration of mud, which is transported out of the shield machine by the mud discharge pipeline and enters the slurry separation system on the ground for treatment.
Every 2 meters forward, the TBM stops to assemble the prefabricated segments, which are connected together in a circular shape.
The shield construction will pass through the silty clay, silty fine sand, medium coarse sand, round gravel and other strata of the Yangtze River floodplain, and the biggest test is that it needs to pass through about 700 meters of moderately weathered argillaceous sandstone strata. As the most critical construction section of the second phase of Line 4, the “New Journey” slurry balance shield machine will complete the most difficult and technical part of the whole line.
The second phase of Metro Line 4 is the fourth cross-river subway built in Nanjing after Metro Line 3, Line 10 and the first phase of Ninghe Intercity. After completion, it can accelerate the integrated development of Nanjing’s cross-river development, improve the urban rail transit network, strengthen the connection between Nanjing Jiangbei New Area and the main city, and alleviate the pressure of cross-river traffic.
