First Shield Machine Launched in Jiang-Ai Section

　　Recently, as the rotating cutterhead of the "Shencheng No. 1" shield machine slowly turned, it marked the smooth breakthrough of the downline shield tunnel in the Jiang-Ai section of Shanghai Rail Transit Line 18 Phase II — the first application of the new embedded socket-type segment technology — creating favorable conditions for subsequent construction.

　　The downline of the Jiang-Ai section has a total length of 1,587.728 meters, comprising 1,324 rings. During construction, the tunnel passed beneath important structures including railways, power tunnels, raw water pipelines and river channels, entailing high safety risks and great technical difficulty. To ensure smooth construction, the project department implemented a 24-hour leadership duty system, set up trial sections in advance, optimized tunneling parameters, and combined manual and automated monitoring so that monitoring data could guide construction in real time, safeguarding the railway and other important pipelines. To ensure the orderly advancement of the shield machine, the Urban Construction Branch gave full play to its professional strengths by conducting hands-on training in advance to improve workers' practical skills.

　　In response to construction difficulties such as the high precision and great difficulty of assembling socket-type segments and the tendency of segments to float upward when exiting the shield tail, the project team modified the segment erector in advance, raising assembly precision to a new level of 1.5 millimeters — far exceeding design and code requirements — truly achieving the Grade 1 waterproofing goal of a "flawless" tunnel and accumulating valuable experience for similar shield tunneling. The project department set up a technical task force and strengthened standardized and refined management, installing segment tensioning devices, segment anti-floating devices, infrared laser positioning devices on the erector, and vacuum pumps, which effectively improved segment roundness, sealing performance and safety while reducing leakage rates and maintenance, greatly minimizing later tunnel deformation and replacement costs. Since shield construction began, the project has won 3 QC achievements at provincial/ministerial level or above and attracted observation and study visits from multiple units along the line.

　　It is reported that after the second phase of Shanghai Rail Transit Line 18 is completed and opened to traffic, it will further improve Shanghai's rail transit network structure, enhance east-west transport capacity in the northern part of the main urban area, and serve the transformation and development of the Wusong area. Next, the project team will make preparations for receiving the remaining 3 shield machines, ensuring the safe, high-quality and efficient completion of the remaining section construction tasks and contributing to the early opening of the entire line.