Soldier Pile Wall

[moe333]

Hi all,

I'm working on a conceptual design for a soldier pile wall to retain a 2 lane road approximately 100 feet long. The exposed height of the wall will be about 20 feet. A masonry wall is currently retaining the road and the soldier pile wall would be constructed against the masonry wall, leaving the masonry wall in place. There are no details for the masonry wall. The masonry wall is retaining very moist, medium stiff silty clay/MH fill. The soil below the wall is native, very moist to saturated, stiff silty clay/MH (saprolite) with Su about 2 ksf.

The concept is to drill holes, insert H-beams, and fill the holes with concrete. Lagging would be used between the drilled holes and crushed rock would be used as backfill to provide drainage. Not a lot of experience with designing this type of system so I was looking for suggestions regarding the following:

Pile depth and spacing, type of lagging, pile grouting/concrete, typical H-pile size, wall backfill, any other important considerations?

With this type of system require a tieback or deadman, or will a cantilever be sufficient?

Thanks in advance

 

[Ron]

What is the topography on the active side of the pile? If it is sloped, I'd be concerned about cantilevering. If flat, then I would expect the embedment to be in the 40 to 50-foot range.

Considering the soil type, I would be concerned about lateral consolidation under the constant lateral load. For that reason, I would use a deadman. Lateral load at the top of ground from the retained soil/block wall is pretty close to your soil strength, so no safety factor there...another reason for the deadman or you'll potentially have a lot of lateral movement of the pile at the ground level.

 

[PEinc]

It sounds to me like the 20' exposed soldier beam wall would need to be tiedback with drilled-in tieback anchors or tie rods and deadmen. 20' is usually too high to cantilever. Also, 40 to 50 feet of soldier beam embedment is astronomical! However, if you plan to tie it back with drilled-in tieback anchors, you will probably have drill access problems and the tiebacks could be expensive. Instead of soldier beams and tieback anchors, it might be possible and economical to just soil nail the existing masonry wall, add weep holes and vertical chimney drains, and then apply a shotcrete or CIP concrete facing.

http://www.PeirceEngineering.com

 

[moe333]

The topography on the active side is level for about 30 feet then descends at about 1.5H:1V.

PEinc, the soil nails would react against the existing masonry wall (if suitable)? or against the new facing?

 

[PEinc]

Either. However, my preference would be to install the nails against the existing wall (as long as it is in fairly good shape) and then attach a new facing that covers the nail heads and chimney drains. The facing would attach to headed tension studs welded to oversized soil nail bearing plates.

http://www.PeirceEngineering.com

 

[VAD]

moe333

The existing masonry wall was presumably constucted several years ago provides the clue to this problem. Are there any problems with the roadway. The reason for using a masonry wall was likely because the soil was capable of standing vertically given its nature. Soil nailing seems appropriate as provided by PEinc. If the soldier pile wall is required then constructing it to cantilever is satisfactory. All the existing wall requires is a slight brace to be happy again and this wall can be constructed as you indicated. The lateral pressures would be small - silo effect. Off hand use the piles at 2 m spacing. Depth of embeddment of pile about 4 m . Use H 310 x 110 kg/m piles. Use 900 mm diameter pile holes. Minimum size should be 600 mm. If so use H 250x 63 kg/m piles? Cantilever is sufficient unless the wall would be in the constant view of the public and hence a perfectly straight alignment is required. If it is in the boonies no problem.

Caution:Ensure first that the reason for this new wall is not as aresult of a slide problem that is manifested in the roadway re cracks -semi circular, depressions etc. If so then one wants to determine if a slide plane has developed ad its extent in depth. If tthis is now in the making the information provided can suffice. However, it is always good to investigate the problem before applying a solution. Looks like an interseting study,