Sheet Piling Pre Basement Dig

[Internet Know How]

Hey,

 

Any idea how much per linear meter I could be looking at to sheet pile? I have about 25-30 meters to do before digging out

 

Thanks

 

Chris

[Mr Punter]

Are you near neighbouring structures?

[Internet Know How]

only the party wall either side which is why I need to sheet pile. 

[Russell griffiths]

Has this been designed by a structural engineer, who’s insurance is covering it if it moves, 

 

i think you are going about this the  wrong way 

 

you need a groundworks company to sheet pile, dig out and prepare for slab all in one package, fully insured, in house structural engineer. 

 

Looking at your other posts you could be in for a painful experience trying to use a bloke with a digger on a site where you are supporting two neighbours properties. 

 

Are you sure 3m sticking out of the ground will hold back the load, sheet piles bend quite considerably, you normally have an internal beam fixing them together and maybe some props. 

 

[Declan52]

Before you start you need to know what's down there. A site investigation would be needed to determine how far you need to dig out plus how deep your piles need to go. You can't have the piles sitting on ground material that isn't strong enough to hold back the force of what's on the other side. So the site investigation will determine the depth of the pile which will effect the size of the rig needed to push the pile into the ground which will then add more £££ to the bill.

If your going to do a basement that requires sheet piling due to close proximity of neighbouring houses and not get a site investigation done your being very very foolish.

[Internet Know How]

50 minutes ago, Russell griffiths said:

Has this been designed by a structural engineer, who’s insurance is covering it if it moves, 

 

i think you are going about this the  wrong way 

 

you need a groundworks company to sheet pile, dig out and prepare for slab all in one package, fully insured, in house structural engineer. 

 

Looking at your other posts you could be in for a painful experience trying to use a bloke with a digger on a site where you are supporting two neighbours properties. 

 

Are you sure 3m sticking out of the ground will hold back the load, sheet piles bend quite considerably, you normally have an internal beam fixing them together and maybe some props. 

 

Its to shore up up a 1mm party wall. The neighbours property is another 4 meters on both sides. In fact, we may actually take this party wall down and replace it, so there will be less load to hold back. Once we are back at ground level, we will place in new footings and build a new 900mm height wall

[Internet Know How]

44 minutes ago, Declan52 said:

Before you start you need to know what's down there. A site investigation would be needed to determine how far you need to dig out plus how deep your piles need to go. You can't have the piles sitting on ground material that isn't strong enough to hold back the force of what's on the other side. So the site investigation will determine the depth of the pile which will effect the size of the rig needed to push the pile into the ground which will then add more £££ to the bill.

If your going to do a basement that requires sheet piling due to close proximity of neighbouring houses and not get a site investigation done your being very very foolish.

Site investigation has to be done. At this point, with my knowledge of the ground, being all sand, and with a 3m basement dig, I estimated a minimum of 6m sheet piles. We may even have to go for slightly longer to get longer piles in the ground.

 

Neighboring properties are not so much the issue given their location to our dig, but the party walls are. As I said in another response, we may even take down these party walls with agreement from the neighbours because they are not in the best condition anyway. 

 

fyi our site investigation will go down 6m, then potentially up to another 20m depending on whether peat is present. No corners will be cut on this one, only contractors that try and overcharge the going rate

[Adam2]

I had considered trench sheets and went with a king post wall instead. In sand/sandstone - 7m long steels with ~2.8 out the ground. an SE did the spec. These are super quick to install and only needed a small piling rig. May be worth considering that as well. For a reference point, SE cost was 800

[Internet Know How]

3 minutes ago, Adam2 said:

I had considered trench sheets and went with a king post wall instead. In sand/sandstone - 7m long steels with ~2.8 out the ground. an SE did the spec. These are super quick to install and only needed a small piling rig. May be worth considering that as well. For a reference point, SE cost was 800

Thanks Adam, I will look into this too

 

[scottishjohn]

you mentioned sand as sub soil in one post and now peat --not a combination I have ever heard of 

peat needs bog to form --sand is free draining  very strange 

[Internet Know How]

1 hour ago, scottishjohn said:

you mentioned sand as sub soil in one post and now peat --not a combination I have ever heard of 

peat needs bog to form --sand is free draining  very strange 

Its sand sub soil with layers of peat in areas in the vicinity. The peat may not be on my plot necessarily but it has been found in the area. My ground investigation will confirm

[Internet Know How]

On 17/10/2020 at 18:28, Adam2 said:

I had considered trench sheets and went with a king post wall instead. In sand/sandstone - 7m long steels with ~2.8 out the ground. an SE did the spec. These are super quick to install and only needed a small piling rig. May be worth considering that as well. For a reference point, SE cost was 800

How did you install the steels? Was it direct pile drive or did you dig with an auger and fill with concrete then drop in the steels? King post walls do offer more support than sheet piles from the designs I have seen

[Adam2]

Hi - since then we've done another  set this time 9m steels 6m in ground and 3m retained. We used a piling co with a decent auger machine to make the holes - really efficient machine, 1.5 days for the 4 holes. My team then placed the steels using a 13T excavator to lift them that we had on site then concrete dropped in. We had 40 timbers on-site ready to drop in as we excavated. 

 

I don't think you can drive I beams - well if you can I'd worry about the ground 

 

General rule I understand for this is 2/3 in ground to retain 1/3 out but of course depends on conditions. We're in pretty stable compacted sand/sandstone and had an engineer a design the original one so followed that for the latest one. Ours is temp for about 8 weeks then when we backfill will remove as many timbers as possible, at least 2/3 of them to minimise long term decay which may (according to SE) cause some degree of subsidence in ground above

[Mr Punter]

I have done similar with sleepers but just had 6m steels with 2.7m left in the ground.  It was only for working area.  Where there was a neighbouring structure (garage) we augered 6.0m hit and miss holes, put in a small amount of reinforcing the full depth and concreted before we excavated.