Chinese workers building what would be the world’s longest tunnel have come up against an unexpected problem in one of the driest areas on Earth – gushing streams of water.
That is according to engineers involved in the project in China’s far western Xinjiang region, more than half of which is made up of vast expanses of arid desert.
“High groundwater levels have caused frequent water inrush accidents that seriously affected the construction schedule,” said Deng Mingjiang, a professor with the Chinese Academy of Engineering, in a paper published in domestic peer-reviewed journal Tunnel Construction last month.
Deng’s team has been working on an ambitious project to introduce snowmelt from the Altai Mountains into the deserts of northern Xinjiang through deeply buried tunnels more than 500km (310 miles) long.
Kashuang tunnel, the longest of the three mega tunnels in the project, is expected to stretch for 280km (174 miles), more than twice as long as the Delaware Aqueduct – the main water supply tunnel of New York City – which has held the record since 1945.
But from time to time, the tunnel boring machines (TBMs) run into an unusually rich groundwater source that bursts out so forcefully that it could fill a swimming pool in an hour.
Every time the flooding alarm flashed red, the report said, workers would need to evacuate and the giant boring machine would be made to stop and pull back immediately or risk serious damage.