Piled Wall
Piled Wall
(OP)
I am going to design piles to be installed in embankment which carries railway tracks. After the piling has been done, the side slope in front of the piled wall will be excavated.
My questions are:
1) What was used to fill up the embankment (200 years ago!) is not known yet at this stage. I wonder whether CFA can be used if boulders or cobbles are found during augering. If augers are too weak to drill through obstructions, are there any alternatives?
2) If retained height is 4 metres and surchange from the tracks is 45 kN/m^2, does anybody have a rough figure about how deep the piles should go (i.e. below the 4m deep formation level)?
Thanks!!
My questions are:
1) What was used to fill up the embankment (200 years ago!) is not known yet at this stage. I wonder whether CFA can be used if boulders or cobbles are found during augering. If augers are too weak to drill through obstructions, are there any alternatives?
2) If retained height is 4 metres and surchange from the tracks is 45 kN/m^2, does anybody have a rough figure about how deep the piles should go (i.e. below the 4m deep formation level)?
Thanks!!





RE: Piled Wall
RE: Piled Wall
RE: Piled Wall
Sound like by your terminology you are in the UK.
In this case it would be a network rail job and I would strongly advise you to get a geotechnical investigation done. Network Rail demand a very auditable and robust design process that can be fully defended.
If it is all fill then it is unlikely that there will be any large rock floaters in there.
The piled wall that you refer to is usually called contiguous piling or a secant pile wall and I suggest you google it to look into it a bit more.
A publication by CIRIA gives very good info on this type of construction.
As for the length of the piles, it depends on the quality of the soil and the allowable deflection of the piles. As a rough initial guess I would say you embedment would be an additional twice the retained height giving a 12m total length.
Regarding the deflection, in theory every mm the piles deflect will give half a mm of vertical settlement behind the piles.
RE: Piled Wall
What the client wants to do is to demolish the masonry brick viaduct (i.e. the arch), which support the sidings, and the adjacent masonry retaining wall. Before the demolition, some sort of retaining structure should be in place. That is why I want to do a new wall there.
I understand a geotechnical investigation should be done, but this project is still at stage of feasibility study. Hence, I have to work out a "workable" solution with limited information.
By the way, how far the new wall (piled wall and sheet pile wall) should be away from the existing masonry retaining wall?
Thanks!!
RE: Piled Wall