7 June 2009

The race against time to save 27 miners trapped below the Chongqing landslide

Posted by Dave Petley

In China there is now a dramatic race against time being played out as rescuers race to reach 27 miners trapped below the Chongqing landslide. Xinhua is reporting that the two entrances to the Jiwei Mountain Iron Ore mine were blocked by the landslide. The trapped miners are likely to be able to survive for five to seven days, so there is very limited time available. Rescuers are now trying to blast a 40 m deep shaft through the landslide debris to reach the miners, as this Xinhua image shows:

To facilitate this the rescuers have build a road to bring in heavy machinery and now have access to a heavy lift helicopter.

However, we should not under-estimate the difficulties of this task. First, the landslide debris looks to be incredibly coarse, which will mean that digging a shaft or a tunnel is very difficult indeed, as this Xinhua image shows (note the rescuers for scale):

Third, the debris will be at its dry angle of repose and so is only just stable. Therefore, digging into will potentially destabilise the mass above. Supporting a tunnel or shaft in this material is not going to be easy. Finally, of course, rainfall would be very dangerous. The rainy season is just starting. Therefore, there are substantial risks to the rescuers as well as the miners.

Meanwhile, the slide, which is now estimated to have a volume of 12 million cubic metres, has also blocked the valley, such that a lake is forming. Once again the Chinese are having to build a drainage channel and evacuate people downstream and within the lake area.

The number killed by the landslide is very unclear at present, but the best estimate seems to be 79 buried by the landslide plus the 27 miners.