MSE Wall - Off Plumb

[NCIndiana]

Approximately 15ft tall MSE bridge abutment wall (non-load bearing, enclosing a pile and pile-cap system), observed during construction that it was going up slightly off plumb (away from fill), but visually perceptible when looked at carefully. After erection, it has come up for situational assessment and if needed, remediation recommendations. Obviously, it is too early to observe if the tilt is progressive. However, if it is observed to be non-progressive, is there a need to remediate with this type of system? If so, what might that remediation be? Is there any structural concern at its current condition, considering that it was observed to be going off-plumb during erection?

 

[ishvaaag]

The main concern I see is if the lack of verticality is from some lack of anchorage short-term that may affect structural life or affect structure. If unsafe from now on, at least restitution of proper anchor action would be required.

 

[hokie66]

Whether or not there are structural concerns about the wall, a retaining wall should never be built out of plumb away from the fill. Visual perception is crucial for confidence in the built environment. As this was noticed during construction, it should have been rectified at that point by starting over.

 

[Drumchaser]

There is usually a vertical tolerance with-in your spec.s, which appears to have been exceeded.
Aside from the aesthetics, someone is not getting what they paid for ( not even considering the failure aspect )

Constructing a MSE wall out of plumb is not uncommon when not following the installation procedures provided by the designer. If the backfill is "sand", and the coping and or level pad has not been completed, I have seen *sections* of walls "eased back plumb with a trackhoe.

Deconstructing and reconstructing of course will be expensive, but also the prudent thing to do.

My wild speculation would be that during bkfl placement a compactor or such got too close to the wall and pooched it out.

 

[oldestguy]

What might help would be to tell more of the details, such as the dimensions of the facing materials, length and type of the "ties", etc. and then ask this question: "How many of these out of plumb walls have you seen fail?"

Then, you might be in a better position to estimate the chances of failure, of course having made some measurements of any progressive movements.

 

[msucog]

if the owner doesn't mind the visual aspects of the wall, then pose the question to the wall designer so that they can address the matter from a "will it be okay?" standpoint. (i'm surprised that they allowed the wall construction to continue knowing that it was so far out of the intended vertical alignment).

and i would never suggest trying to nudge a wall with a trackhoe. if it's properly compacted fill then you're wasting your time anyway without even considering all the effects of what happens if you do manage to actually lean the wall back in to the fill after it's already constructed.

 

[NCIndiana]

Thank you all for taking time to respond. Generally in accordance with prudent thinking that I anticipated.

 

[wedlmic]

hokie66 hit it on the nail. For a DOT project, out-of-plumb is not acceptable. Any issue with stability is a public safety concern. Hopefully the pile cap and piles were designed completely independent of the facing wall - ie - the wall could be completely removed and the abutment would remain stable. It is difficult to fix an MSE wall when the problem is at the base - I have seen walers cast, tiebacks installed and buttress walls cast against the failed sections. All of them look hokie (sorry hokie66). The EOR has a tough decision - the state agency can solve it for him - remove and replace.

Wedlmic

 

[MSEMan]

There are many MSE walls in service that have negative batter. The situation probably arose due to the difficulty of working in the confined spaces between the piles and the wall face. Depending on the fill used, the contractor may have found it difficult to get adequate compaction in these confined areas and may have exerted too much compactive effort near the wall. You're absolutely right to make sure that the movement isn't continuing and probably (contractually) within your rights to have the wall rebuilt, but you need to judge whether it's in the interests of everyone concerned to re-build considering that its probably an aesthetic issue.

 

[msquared48]

I would suspect over compaction of the backfill with too heavy of equipment causing the deflection.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask