Tunnel boring machine (TBM) Qinlong 31 completed the left-hand tunnel between Longteng Street and Zhanjiaqiao Road stations on 12 October, marking a milestone for contract SG15-15.<\/p>\n
Launched from Longteng Street Station on 3 April, the machine navigated complex underground conditions involving existing roads, residential developments, waterways and the Nanjing\u2013Hangzhou high-speed railway.<\/p>\n
The most challenging section involved tunnelling beneath an operational high-speed railway viaduct, where eight existing road sheet-pile elements obstructed the tunnel alignment.<\/p>\n
Instead of removing the obstructions before excavation, the project team adopted an in-situ cutting technique that enabled the TBM to cut directly through the piles while protecting the railway\u2019s supporting structures.<\/p>\n
The operation required precise identification of pile locations, optimisation of cutterhead parameters and continuous adjustments to excavation rates as the machine passed through the affected ground.<\/p>\n
The railway undercrossing was completed in July. During the 18-day operation, the TBM installed 69 segment rings without interrupting high-speed railway services. According to the contractor, ground settlement remained within permitted limits, and no safety warnings were triggered.<\/p>\n
The technique is reported to be the first application in China of direct TBM pile cutting under the combined conditions of an operational high-speed railway viaduct and existing road sheet-pile obstructions.<\/p>\n
To control risks during excavation, the project team used an intelligent construction management platform to monitor TBM operating parameters, synchronous grouting, ground movement and machine alignment.<\/p>\n
Ground improvement measures and enhanced settlement monitoring were also implemented. The team adjusted soil conditioning and grouting operations to maintain ground stability throughout the railway undercrossing.<\/p>\n
The parallel right-hand tunnel is being excavated by Qinlong 32, a 6.47m-diameter earth pressure balance machine (EPBM), along a 768.2m drive.<\/p>\n
The alignment includes a minimum curve radius of 380m and nine existing pile obstructions. Qinlong 32 passed beneath the Nanjing\u2013Hangzhou high-speed railway in September, with excavation of the remaining section continuing.<\/p>\n
The project team said the successful use of in-situ pile cutting could provide a reference for future metro tunnelling projects beneath operational high-speed railway infrastructure, particularly where existing foundations cannot readily be removed.<\/p>\n","protected":false},"excerpt":{"rendered":"
Tunnel boring machine (TBM) Qinlong 31 completed the left-hand tunnel between Longteng Street and Zhanjiaqiao Road stations on 12 October, marking a milestone for contract SG15-15. Launched from Longteng Street Station on 3 April, the machine navigated complex underground conditions involving existing roads, residential developments, waterways and the Nanjing\u2013Hangzhou high-speed railway. TBM cuts through existing foundation obstructions The most challenging section involved tunnelling beneath an operational high-speed railway viaduct, where eight existing road sheet-pile elements obstructed the tunnel alignment. Instead of removing the obstructions before excavation, the project team adopted an in-situ cutting technique that enabled the TBM to cut […]<\/p>\n","protected":false},"author":5,"featured_media":20742,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[41],"tags":[5724,5723],"class_list":["post-20741","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news","tag-801-m-drive","tag-hangzhou-metro-line-15","post--single"],"yoast_head":"\n