Retaining wall

[Tasdevil]

Have a 2.5 m high retaining wall adjacent to a field. It has two sections of 6 m long. Built with hollow concrete blocks with steel reinforcing rods inside blocks and filled with concrete. It is quite substantial but the top has moved out of plumb by about 15-20 cms. The farmer only agrees to steel RSJ's be used to support the wall on the field side. Would 3 RSJ's be sufficient for each section , bedded in concrete foundation pad of say 800 x 800 x 500 deep. These are really only a precaution to stop the wall moving any further, no imminent danger of collapsing etc.
Any comments / suggestions would be welcome.

 

[Norcon]

If your pulling in excavators and equipment then you might as well put a cubic meter at each rsj.

Ideally the rsj's would be cased in with concrete also.

You might hit the foundation when you dig down. You'll want the rsj buried in concrete to about a couple of feet.

You also need to be careful with the excavating as that might cause the wall to topple and then you'll have a real abortion on your hands.

Did a 6m tall one a few years ago that was leaning with about 3.5 cube at each hole. The rsj's were massive.

We have a 50m long x 3.6m tall x 0.400m retainer in the formwork construction phase this week which will see about 70 cube sitting dead vertical by Saturday.
A bulldozer will backfill it to the top with heavy clay. It won't lean.

 

[Tasdevil]

Thanks for response, take your point about causing wall to topple. Had in mind to do one hole for each section at a time until all six are in place over a period of time. As for RSJ's , what dimensions do you think would be strong enough, the length will be about 3 metres.

 

[Norcon]

200mm x 100mm.
One at a time sounds good. Though we would probably prop the wall and pour all six together from a single load of concrete.
Depends on what type of equipment you can lay your hands on at the end of the day.

 

[Tasdevil]

Thanks Norcon, unfortunately site access is difficult (ploughed field) , so would have to mix concrete nearby and barrow it around edge of field ! , or if time allows we will have to wait for the field to be unused for a while then do it. Thanks for size info, I take it that this would be the usual H section, or would it be a column Box section.?

 

[theoldun]

Thanks Norcon, unfortunately site access is difficult (ploughed field) , so would have to mix concrete nearby and barrow it around edge of field ! , or if time allows we will have to wait for the field to be unused for a while then do it.

That will be no problem for Norcon. On his initial survey he will arrive in either a Cobra or Apache in case he wants to adjust the general contours and ground levels. Muck away will be by a LYnx, and concrete will be carried in by a Chinook. Start to finish will be 4hours 28 minutes.

Tasdevil . On a serious note you state that USBs will be on farmers side. They will be as much use as a chocolate kettle on that side. They need to go on your side, but not the way you intend to do it.
Regards oldun

 

[Tasdevil]

Hi to theoldun , can you enlighten me as to what you would advise then. I thought the RSJ's would need to be against the wall , ie on the farmers side?
Don't have access to all those helicopters but do have a wheelbarrow. Be interested on your thoughts

 

[Norcon]

Another method we use is this...
http://tinyurl.com/n23uxuz

H section is best.

 

[theprinceofdarkness]

I can not understand what the situation is. So the field was on a hill and some one has cut a section out to give a flat area, so the field is 8' higher then the flat ground? Or some one has constructed their own plateau that is 8' higher then the field?
Steel rods are only any good if their foundations are deep enough to stop them rotating - this is what has happened to the wall.
have you considered land anchors?
Frank

 

[Norcon]

The field will be lower and most likely sloping.
We've done dozens of concrete retaining walls to enable sites to be extended.

 

[Tasdevil]

To clarify the location, our property is the last one in a small close which travels downhill. Many years ago the garden sloped down to the field. Before we got the property th previous owners had an extension built and a high wall also built and to enable them to build this they 'built up' the land to its current height above the field. That means the extension and patio are now 2.5 metres higher than the field below. The retaining wall is there to stop the property sliding into the field and it is this wall that is beginning to lean towards the field. Hope that gives the picture of it all.