Wedoany.com Report on Feb 14th, Recently, after nearly 25 hours of continuous operation, the underwater base sealing concrete pouring task for Shaft No. 2 of the Chongtai Yangtze River Tunnel Project was successfully completed. This has built a "safe foundation" for the shaft structure, marking the official entry of the shaft into the internal structure construction phase. The breakthrough at this key milestone lays a crucial foundation for the subsequent reception and secondary launch of the "Linghanghao" shield tunneling machine.
The Chongtai Yangtze River Tunnel Project has a total length of 14.25 kilometers and includes three shafts. Among them, Shaft No. 2 is located in Taicang City, Jiangsu Province. It has an excavation diameter of 24 meters, a digging depth of 56.08 meters, and is situated only 200 meters from the south bank embankment of the Yangtze River. It is classified as an ultra-deep, water-rich circular shaft structure under conditions of a riverside floodplain. The base sealing of the shaft is a key controlling process in tunnel construction, requiring it to withstand challenges such as high water pressure (6 bar), extreme water depth (a sealing depth of 56 meters), and large-volume concrete pouring (approximately 4700 cubic meters poured at once). It serves as the first line of defense ensuring structural safety, waterproofing, seepage resistance, and anti-flotation.
Faced with complex working conditions, the tunnel project team overcame numerous challenges through technological innovation: they developed a concrete mix ratio with high anti-dispersion and high fluidity to achieve self-leveling and compaction in deep-water environments; they employed a "Fin Drone underwater UAV" and a "Huace DGPS unmanned vessel - multi-beam ultrasonic dual-frequency echo sounder" for real-time monitoring of mud accumulation on the shaft walls and sediment settlement at the base; they developed special equipment for laying geogrids at a depth of 56 meters underwater to ensure precise positioning and fixation; they applied the "Pouring Assurance" system to dynamically control the concrete pouring height; they optimized the conduit layout scheme, limiting the diffusion radius to within 4 meters, and conducted a watertightness test at 1.5 times the working pressure; they formulated a special winter construction plan, strictly controlling the concrete's placement temperature and setting process to ensure the quality of underwater construction.
The successful construction of Shaft No. 2 not only provides safety assurance for the shield machine's reception and secondary launch but also holds decisive significance for the completion of the entire tunnel project. Upon completion, the project will significantly shorten the travel time between Shanghai, Nanjing, and Hefei. The journey from Chongming to Shanghai Baoshan Station will take only 17 minutes, strongly promoting the construction of the "Rail-based Yangtze River Delta" and serving the high-quality development of the Yangtze River Economic Belt.
