Recently, construction workers from China Railway 14th Bureau Group have been braving the intense heat to rush the assembly of the "Ningwu" shield tunneling machine at the shield launching shaft of the Nanjing South Tunnel on the Ningwu Railway capacity expansion and renovation project.

According to introductions, the Nanjing South Tunnel is a controlling project for the entire Ningwu Railway capacity expansion and renovation project. It spans Qinhuai District, Yuhuatai District, and Jiangning District of Nanjing, passing beneath trunk railways such as the Nanjing-Anqing High-Speed Railway, Beijing-Shanghai High-Speed Railway, and Shanghai-Chengdu Railway, as well as major transportation arteries including Ningdan Highway and Niushou Avenue. With a total length of 14.442 kilometers, it is a single-tube single-track tunnel designed for a speed of 120 kilometers per hour. The shield tunneling section is approximately 2.4 kilometers long and passes through strata such as argillaceous sandstone and silty sandstone, characterized by numerous water bodies and complex surface and underground environments. In particular, where the shield machine passes beneath the new Qinhuai River section, the shallowest cover soil is only 2.6 meters, which is the shallowest cover soil layer encountered in domestic shield tunneling projects to date. In response to the many construction difficulties, high safety risks, and complex technical conditions of the shield tunneling section of the Nanjing South Tunnel, the project construction management unit, the Hefei Railway Hub Project Construction Command, organized participating units including China Railway 14th Bureau Group to jointly develop and manufacture the "Ningwu" shield tunneling machine with China Railway Construction Heavy Industry Group at the Changsha Shield Industry Base. The shield machine has an excavation diameter of 9.33 meters, a total length of 132 meters, a weight of approximately 1,375 tons, and a total installed power of 4,305 kilowatts.

Currently, assembly of the "Ningwu" shield tunneling machine is about 80% complete, with shield body installation underway. The cutterhead assembly is scheduled to be completed by the end of July 2024, and launching is planned for mid-August.