7 February 2022

An unusual embankment failure near to Northampton

Posted by Dave Petley

An unusual embankment failure near to Northampton

In the late autumn of in 2021 I was driving south from Sheffield to visit my daughter near to London in the UK.  I was on the M1 motorway close to the town of Northampton, in heavy traffic, when I fleetingly spotted what appeared to be surprisingly large, very new landslide in an embankment.  The location was very close to junction 15A; the landslide was in a newly constructed, steep berm around a new warehouse site.

Of course, it wasn’t possible to stop to take a look, so my view of the site was very brief.  I drove the same road this weekend – the failure has now been excavated.

However, interestingly, the landslide has been captured on Google Street view, from several perspectives.  This image was collected in October 2021:-

The embankment failure near to Northampton.

The embankment failure near to Northampton. Image from Google StreetView.

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The location is 52.207, -0.933.  The most recent Google Earth image shows the embankment under construction in September 2021.

This is an alternative view from a few metres further along the road:-

Another view of the embankment failure near to Northampton.

Another view of the embankment failure near to Northampton. Image from Google StreetView.

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This appears to be a rotational failure / slump in the embankment.  The mechanisms of failure are quite complex, with considerable plastic deformation on the margins of the failed block:-

Detailed view of the embankment failure near to Northampton

Detailed view of the embankment failure near to Northampton. Image from Google StreetView.

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Unsurprisingly, there is nothing online about this landslide.  I’m quite intrigued by two aspects of it though.  First, what caused this section of the embankment to fail whilst the remainder of the embankment remains intact?  Was it built to a different specification (for example different materials or drainage), or using a different method, or is there something about the ground conditions that meant that it was susceptible to failure?

And second, the remaining embankment is remarkably steep and high.  How confident can the designers be that a similar failure won’t happen at another location on this embankment?