1 April 2021
Düzce Zonguldak: a spectacular retaining wall failure on a highway in Turkey
On 26 March 2021 a spectacular retaining slope failure occurred on a highway at Düzce Zonguldak in Turkey. I haven’t seen any images of this failure in the UK media, which is a shame as it is an unusual event. Haber Golkoy has this image of the landslide:-
According to the news reports the slope failed overnight. No-one was hurt. Unsurprisingly, the road is now closed, with traffic being diverted onto local roads. This view, from an image posted by Cumhuriyet, provides a better idea of the materials involved:-
It is interesting that the road has been built across a topographic depression on an embankment made from fill. I am no expert on retaining structures – is this a mechanically stabilised retaining wall? [In the comments below Fabien Peyrel has confirmed that this is a Mechanically stabilized earth (MSE or reinforced soil) structure]. The wall has slumped spectacularly.
Scenarios for this event here could include failure through the foundation of the structure (a bearing capacity failure) and/or a build up of excessive pore water pressures in the fill causing a fillslope failure. The latter would imply inadequate drainage of the fill, either because of poor design or construction, or because of poor maintenance. Again, I would be very interested in the views of others in the comments.
The news reports suggest that the road at Düzce Zonguldak was opened in 2012. The highway was reportedly constructed by Limak Holding.
Clearly reconstruction of this highway is going to be a substantial task. If the failure is the result of a design, construction or maintenance error then other sections of the road may well be at risk too.