WTC 2024 | TUNNELLING IN CHINA
WTC2024 IN SHENZHEN: TECHNICAL SITE VISITS In addition to the seven projects available for Technical Site visits (see Box Panel-1), some other large and challenging projects will
also be highlighted during WTC 2024. They are:
Qingdao 2nd Undersea Road Tunnel, in Shandong Province: Connecting Qingdao and Huangdao Island, (see Figure 5), this tunnel, when completed in 2027, will for a time be the world’s longest undersea road tunnel (length: 14.37km). Being built by D&B and three TBMs, the project consists of three tubes, including two main tubes with three lanes each, and one service tube. The distance between the two main tubes is approximately 55m, and the deepest point of the tunnel alignment is 115m below sea level. The project poses significant challenges due to its complex geology.
No.1 Daliang Mountain Highway Tunnel, in Sichuan Province: At 15.3km in length, this tunnel is one of the longest highway tunnels under construction in mainland China. It comprises three tubes, with two main tubes and one service tube. The main tunnels are constructed using D&B, while the service tunnel employs a hard rock TBM. This project, the first highway tunnel in mainland China to utilize a TBM (see Figure 6), successfully completed its service tube in September this year. The main tubes are still under construction. The project is expected to be completed and operational in 2024.
Gaoligong Mountain Railway Tunnel, in Yunnan Province: This 34.5km-long project consists of one main tunnel and one parallel pilot tunnel, constructed by both conventional methods and TBM. The geology poses extreme challenges, including three ‘highs’ (high ground temperature, high ground stress, and high seismic intensity).
In urban areas, the popularity of large-diameter
tunnels has surged due to limited underground space available. As of August 2023, China has 80 large TBM
tunnels either built or under construction with diameters larger than 14m. Of these, 39 have been completed and are in operation, and 41 are under construction – the largest of which is the Ji’nan Huanggang Road Tunnel, utilising a 17.5m-diameter slurry TBM to excavate a 3290m-long section of the 5755m-long tunnel. In the shield TBM market, there are primarily two
categories: single-mode shield TBM and multi-mode shield TBM. Single-mode involves only one excavation method,
such as EPB TBM, Slurry TBM, or Hard rock TBM (open, shield type), while multi-mode offers combinations such as ‘Slurry + EPB,’ ‘EPB + Hard Rock TBM, and ‘Slurry + Hard Rock TBM’. The 6.28m-diameter version of the three-mode TBM
Top, figure 6: Service Tunnel constructed by hard rock TBM of No 1 Daliangshan Highway Tunnel PHOTO CREDIT: LEXI EXPRESSWAY Above, figure 7: Installation of Element 6 of Shenzhen-Zhongshan Link Immersed Tunnel by integrated floating and installation vessel PHOTO CREDIT: SHEN-ZHONG LINK MANAGEMENT CENTER
24 | December 2023
developed by CREG even allows seamless switching between modes, thus enhancing operational efficiency and safety. This technology has been successfully used to complete tunnel boring for the Luogang to Shuixi section of Guangzhou Metro Line 7 (see Figure 2), covering complex conditions on twin 1086m-long tubes passing through hard rock formations, soft soil layers, and working in densely populated areas. To minimise the risks associated with tunnelling in
challenging and complex geological conditions, geology prediction technology has been widely utilised in mainland China for both conventional and mechanised tunnelling.
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