Land Slip - Easenhall Cutting, Brinklow, Oxford Canal

[ditchcrawler]

Looks like CRT's contractors are on the case, there is video on Facebook of them craning in their boats 

[Mike Tee]

Latest C&RT estimate "At least 6 weeks"

[system 4-50]

What's a gabion?

[frangar]

4 minutes ago, system 4-50 said:

What's a gabion?

A metal cage filled with stone or similar 

[Lady M]

According to CRT's newsletter, the landslip was caused by climate change.  Funny that, some of us thought it was due to lack of maintenance.

[Tracy D'arth]

1 hour ago, Lady M said:

According to CRT's newsletter, the landslip was caused by climate change.  Funny that, some of us thought it was due to lack of maintenance.

Oh no, no, no.  Its vandalism surely? Heaven  forbid that the canal would ever need maintenance.

[Lady M]

CRT may believe that climate change is more likely to get them extra funding than vandalism.

[Ronaldo47]

It's also possible that a factor is the original constructors' ignorance of the fact that previously-buried soils can progressively lose strength over decades due to aerial weathering causing chemical changes in their structure, something that only became known from experience.   That has been identified as the cause of failure of numerous railway cuttings that were  built in the Victorian era that have suffered this sort of slumping many decades after their construction. Increased rainfall making the ground wetter won't have helped, but I think we have had wet weather episodes well before climate change was on the agenda.  

 

 

[Jon57]

1 hour ago, Tracy D'arth said:

Oh no, no, no.  Its vandalism surely? Heaven  forbid that the canal would ever need maintenance.

Climate vandellisium 🤣

[The Gravy Boater]

3 hours ago, Lady M said:

According to CRT's newsletter, the landslip was caused by climate change.  Funny that, some of us thought it was due to lack of maintenance.

Yes because we've never had to cope with rain in this country before.  It's like all wet! and slippery! Nightmare... 

[Captain Pegg]

4 hours ago, Lady M said:

According to CRT's newsletter, the landslip was caused by climate change.  Funny that, some of us thought it was due to lack of maintenance.

It’s nothing to do with maintenance since cuttings aren’t really maintainable.

 

CRT have many miles of cuttings and they could if they so wished undertake lots of risk reduction work that is akin to a rebuild using vast amounts of money that they don’t have, never have had, and the public almost certainly wouldn’t want them to have. It would be capital funded work quite different from maintenance and it would consist of work such as devegetation, installation of toe walls, regrading, rock fill, slope drainage and crest drainage. 
 

But because of the relatively random nature of where and when slopes fail it’s far more cost effective to treat the places that do fail post event.

 

It’s not like CRT have to pay damages for closing the canal. The parallel failure of the railway cutting that occurred the same week will have cost six figure sums in penalty payments yet there is a limit on what preventive work rail authorities can undertake and it often comes down to containment rather than prevention. The railway cutting concerned has a series of remediation works undertaken over many, many years but like Easenhall it’s a big cutting and it’s simply not practical to treat it all in a preventive manner.

 

Climate change of course simply increases the likelihood of a failure, it doesn’t cause it.

 

 

Edited February 22 by Captain Pegg

[Mike Tee]

Fingers crossed the other bank at Easenhall doesn't fail, that  IS the railway!

[Captain Pegg]

7 minutes ago, Mike Tee said:

Fingers crossed the other bank at Easenhall doesn't fail, that  IS the railway!

The railway is a bit of a distance away from Easenhall cutting and it’s the Rugby to Nuneaton line that is nearest and the one that parallels the railway between Stretton Stop and Ansty. Whereas the cutting failure that occurred near simultaneously on the railway was on the Rugby to Coventry line.

 

Both sides at Easenhall show signs of past movement.

[Mike Tee]

3 hours ago, Captain Pegg said:

The railway is a bit of a distance away from Easenhall cutting and it’s the Rugby to Nuneaton line that is nearest and the one that parallels the railway between Stretton Stop and Ansty. Whereas the cutting failure that occurred near simultaneously on the railway was on the Rugby to Coventry line.

 

Both sides at Easenhall show signs of past movement.

Whoops! Quite right, I was looking at the wrong bit of Google Earth. For some reason I was looking at the bit west of Rose Narrowboats rather than east.

[ditchcrawler]

From Facebook, for all you all don't like it so just look away now.

 

The Rothen Group

  · 

 

 

We have mobilised two tree cutting teams and wood chippers mounted on spud leg work boats, to carry out works for Kier and the Canal & River Trust at Easenhall, cutting with a large slippage has taken place after recent mass rainfalls.

One team will be working from the South and one from the North.

We will then be mobilising digger and crane boats in order to clear the navigation.

We will keep you updated of the progress of this job. Our teams are working hard to open the navigation as soon as possible.

[Captain Pegg]

20 hours ago, Ronaldo47 said:

It's also possible that a factor is the original constructors' ignorance of the fact that previously-buried soils can progressively lose strength over decades due to aerial weathering causing chemical changes in their structure, something that only became known from experience.   That has been identified as the cause of failure of numerous railway cuttings that were  built in the Victorian era that have suffered this sort of slumping many decades after their construction. Increased rainfall making the ground wetter won't have helped, but I think we have had wet weather episodes well before climate change was on the agenda.  

 

 

 

I've never directly heard of that as a factor quite in the way you describe but it does strike me you may be attempting to describe over-consolidated clay. This is where clays have pore water squeezed out of them by the overburden (the weight of material lying above them in the ground) over a long period of time. If these clays are then extracted and used in construction that process reverses over time leading to a change in behaviour. Clay behaves very differently from other soils.

 

This phenomenon is particularly a problem on the Great Western main line and some other adjoining railways. However it's generally an issue that manifests itself on embankments because of the resulting of loss of track geometry with the movement of the embankment.

 

The risk profile for railways tends to be the opposite of that for canals. The critical risk for canals is breach of the channel (or even worse a water supply reservoir) which is a potential result of embankment failure whereas a cutting slope failure is generally a serviceability issue. For a railway the most immediate danger is a train striking debris from a cutting failure, and particularly being deflected into the path of an oncoming train. Embankment instability tends to be a serviceabilty issue. It's also on onging everyday issue largely because the historic earthworks on Britain's railways and canals were not adequately designed.

[David Mack]

5 hours ago, Captain Pegg said:

 

I've never directly heard of that as a factor quite in the way you describe but it does strike me you may be attempting to describe over-consolidated clay.

...

This phenomenon is particularly a problem on the Great Western main line and some other adjoining railways. However it's generally an issue that manifests itself on embankments because of the resulting of loss of track geometry with the movement of the embankment.

I recall my geotechnical engineering lecturer saying that failure of cuttings in over consolidated clays was also a problem on railways in the Weald of Kent and Sussex. He commented that reversal of the pore pressure state on removal of overburden could take tens of decades - which could be why we are seeing failures in 100-200 year old cuttings.

[Ronaldo47]

Here's an extract from the textbook [☆] from which I got my information about factors affecting landslips.  It seems that there are many possible explanations, and that site surveys and soil analysis are usually required to establish the reasons with any degree of certainty. Removal of overburden as a cause of failure in railway cuttings in clay is mentioned. 

 

Blaming it on climate change without having first made the soil tests and other investigations that such a landslip warrants, seems a bit presumptious! 

Catastrophe extracts.pdf

 

[☆] "Catastrophe- the violent earth", Tony Waltham, Macmillan, first edition, 1978, ISBN 0-333-22595-3 

Edited February 23 by Ronaldo47
typos

[Captain Pegg]

12 hours ago, Ronaldo47 said:

Here's an extract from the textbook [☆] from which I got my information about factors affecting landslips.  It seems that there are many possible explanations, and that site surveys and soil analysis are usually required to establish the reasons with any degree of certainty. Removal of overburden as a cause of failure in railway cuttings in clay is mentioned. 

 

Blaming it on climate change without having first made the soil tests and other investigations that such a landslip warrants, seems a bit presumptious! 

Catastrophe extracts.pdf 629.44 kB · 2 downloads

 

[☆] "Catastrophe- the violent earth", Tony Waltham, Macmillan, first edition, 1978, ISBN 0-333-22595-3 

CRT have perfectly competent geotechnical engineers to do all that stuff and the ability to engage specialists in specific areas where needed.

The notices they publish for boaters are to paint a picture in terms that are understandable to that audience.

 

It’s you that’s clutching stuff out of thin air (or a textbook) that isn’t the cause of the Easenhall failure.

 

Edited February 24 by Captain Pegg

[frangar]

11 hours ago, Ronaldo47 said:

Here's an extract from the textbook [☆] from which I got my information about factors affecting landslips.  It seems that there are many possible explanations, and that site surveys and soil analysis are usually required to establish the reasons with any degree of certainty. Removal of overburden as a cause of failure in railway cuttings in clay is mentioned. 

 

Blaming it on climate change without having first made the soil tests and other investigations that such a landslip warrants, seems a bit presumptious! 

Catastrophe extracts.pdf 629.44 kB · 2 downloads

 

[☆] "Catastrophe- the violent earth", Tony Waltham, Macmillan, first edition, 1978, ISBN 0-333-22595-3 

We have learnt a lot about embankments and cuttings since canals and railways were constructed.
 

Chatting to a senior CRT asset engineer the other week it’s interesting to learn how much less steep the banks would be now if they were constructed to modern thinking. You only have to look at modern roads to see this.

 

Without major land acquisition and reconstruction neither the canals or the railways to some extent will be immune from land slips. 

[ditchcrawler]

There is now another video, don't know what he said as I watched it at double speed. 

 

[MtB]

10 hours ago, ditchcrawler said:

There is now another video, don't know what he said as I watched it at double speed.

 

Isn't this the same bod who posted that 30 minute video of the recovery of the sunken boat on the Soar, which turned out not to contain any footage of the actual recovery?

 

 

 

 

[Captain Pegg]

1 hour ago, MtB said:

 

Isn't this the same bod who posted that 30 minute video of the recovery of the sunken boat on the Soar, which turned out not to contain any footage of the actual recovery?

 

 

 

 

This one doesn’t contain actual footage of the land slip.

[john.k]

Maybe so,but the wet conditions in the field beside the cut was instructional.........standing water in any slight depression..............you d need one of those tractors with the huge tyres from the Euro blockades to get around .........fortunately the harvest seems to have beaten the rain.

[MtB]

15 minutes ago, Captain Pegg said:

This one doesn’t contain actual footage of the land slip.

 

 

Quelle surprise, as Julian Clary would perhaps say...