On August 3, construction of the shield-driven section of the Nanjing South Tunnel in the Ningwu Railway Capacity Expansion and Renovation Project undertaken by China Railway 14th Bureau Group made new progress: the cutterhead of the "Ningwu" shield machine, which has an excavation diameter of 9.33 meters, was successfully lowered into the shaft.

The achievement of this important milestone lays a solid foundation for the subsequent smooth launch of the shield machine.

The Nanjing South Tunnel is a controlling project of the entire Ningwu Railway Capacity Expansion and Renovation Project. It crosses Qinhuai District, Yuhuatai District and Jiangning District of Nanjing, passes beneath trunk railways such as the Nanjing–Anqing high-speed railway, the Beijing–Shanghai high-speed railway and the Shanghai–Chengdu railway as well as major traffic arteries such as Ningdan Highway and Niushou Avenue, and has a total length of 14.442 kilometers. It is a single-tube, single-track tunnel designed for a speed of 120 kilometers per hour, and its shield-driven section is about 2.4 kilometers long. Since May this year, the "Ningwu" shield machine, after being manufactured and rolled off the production line at a factory in Changsha, has been transported to Nanjing in stages for assembly and commissioning.

In recent days, Nanjing has experienced sustained high temperatures and sunny, hot weather, with the scorching sun baking the construction site. The builders have nevertheless remained at their posts, working hard and pressing ahead with the on-site assembly of the shield machine in an intense and orderly manner.

On the morning of that day, the shield machine's cutterhead, weighing 128 tons, was lifted by a crawler crane from the ground to the launch shaft opening and slowly lowered, coming to rest precisely in its predetermined position. Throughout the process, the construction team strictly followed the predetermined plan to ensure the safety and accuracy of every step.

According to reports, the cutterhead tools are the vanguard blades for efficient shield tunneling. In view of the tunnel's geological conditions, they equipped the "Ningwu" shield machine with 238 cutting tools, including 42 inserted-tooth disc cutters and 6 center double disc cutters, achieving "full coverage" of the cutterhead's excavation path, and added disc cutter wear detection to enable real-time monitoring of the tools' condition.

It is understood that the Ningwu Railway Capacity Expansion and Renovation Project starts in the north at Nanjing East Marshalling Station (exclusive) and runs through Qixia District, Qinhuai District, Yuhuatai District and Jiangning District of Nanjing into Ma'anshan City, Anhui Province, then through Dangtu County into Wuhu City, ending at Wuhu East Station (exclusive). Once completed and put into operation, it will further optimize the layout of the regional railway network and is of great significance for implementing the concept of "ecological priority and green development," accelerating the upgrading and adjustment of the industrial structure in areas along the line, optimizing the spatial layout of urbanization, and enhancing the flexibility of the railway network.