Cantilevered abutment wingwalls

[broekie]

I am working on a bridge where I have a full height "retaining wall" abutment supported on piles. My question is really on the wingwalls for these abutments. Because of some utilities in the area that cannot be moved, it will be difficult to have the wingwalls supported on piles.

I was thinking of having the wingwalls cantilever off of the abutment. That way I wouldn't need any kind of footing or piles, and I would minimize my interference with the utilities. The wall would cantilever back approximately 24' from the front face of the abutment. Is this too far? What have people in other states typically done? Any recommendations/insight would be appreciated.

 

[bridgebuster]

My gut says no way. WVDOT uses a caantilevered wing wall but nowhere near 24'

I've done and seen some odd things with wingwalls & abutments. Can you use a soldier pile & lagging wall?

 

[Panars]

I agree that 24 feet seems like too much. I have seen one that had the wingwalls cantilevered about 15 feet. However, they were also turned-back wingwalls at 90 degrees from the abutment and there was a tie-rod that connected the two wingwalls.

 

[Qshake]

Some states have limits and I suspect others will leave it to good engineering.

Limits that i've seen vary from 15 to 21 feet and the work beyond that depends on the type of abutment (open seat or integral).

For integral greater than 15-20' some states show details of a pile supported retaining wall (unless rock is shallow). And for for open seat retaining walls the above applies but if the wall isn't too much greater than 15-20' the wall is placed on a single pile at about the 3/4L point.

Regards,
Qshake

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[graybeach]

broekie,
Have you considered mechanically stabilized earth retaining walls? They do not need to go deep. You could make them continuous across the front of the abutment and have a stub abutment on piles behind.

 

[bridgebuster]

I wouldn't go with MSE and buried utilities. If the utilities have to be excavated there go the MSE ties.

 

[broekie]

Plus this bridge is along a river. I'm not comfortable with MSE walls near running water.

 

[crossframe]

Caltrans often employs cantilevered wingwalls. If the wall becomes too long (somewhere around 20 feet), a pile and small pile cap is placed at the end of the wall.

I believe the Caltrans Bridge Design Manuals are all available on-line as pdf's.

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