A rockfall in Guizhou

One News in New Zealand has an interesting news report including a video of a rockfall event along a highway in Guiyang in Guizhou Province.  The video is embedded from Youtube below, which includes a nice set of images of the aftermath and replays the collapse event several times.

http://www.youtube.com/watch?v=wAP2oQLLUh4

.

Fortunately the potential for collapse had been identified and the road had been closed.  The collapse event appears to have happened on a pre-existing basal release surface and to be defined by a set of existing vertical joints – i.e. in essence this is a complex wedge failure, as this screenshot shows:

.

This collapse is the result of a failure to properly assess the discontinuities in the rock mass during construction.  Such events should be avoidable with proper engineering geological assessment and mitigation.

Images of landslides from the Yunnan earthquake

Meanwhile, Getty Images has a gallery showing landslides triggered by the 5th August 2014 earthquake in Yunnan Province.  I cannot include them here, they are worth a look if you get a chance. Earlier this week six members of a team trying to drain one of the valley-blocking landslides were killed when the dam rapidly failed.  A further 2000 people had to be evacuated.