China has pulled off a daring underground feat, using a multimillion-dollar tunnel boring machine (TBM) to recover its stranded twin beneath the country’s largest river.
The rendezvous between the TBMs was achieved with just 2mm (0.078 inch) of vertical error and no horizontal deviation under the Yangtze’s riverbed, setting a benchmark for precision in deep underground engineering, according to state media on Wednesday.
The feat saved a megaproject that might otherwise have been scrapped.
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In February 2023, an unforeseen failure threatened to derail the 6.4km (4-mile) Jiangyin-Jingjiang Yangtze River Tunnel, a major infrastructure project in China’s eastern Jiangsu province designed to link two industrial zones under dual six-lane highway standards.
Halfway through excavation at a depth of 54 metres (177 feet), a massive 16m-diameter shield tunnelling machine (STM, a variant of a TBM) ground to a sudden halt.
With no way to repair or reverse the STM and under crushing water pressure, the US$50 million machine was effectively entombed, bringing the entire project to a standstill.
