options for spread foundation settling/leaning on 1 side
options for spread foundation settling/leaning on 1 side
(OP)
i have a pipeline support leaning/settling on 1 side. i think this is a spread footing based on the pic.
i'm not the original designer nor have i been to the site to check.
i'm thinking to wait if settling would stop, it still seems to be still supporting the pipeline.
if it continues then i'll replace it.
any options of preventing this foundation from settling further.
also shouldn't foundations really lean/settle a certain amount.
i only check soil bearing and assume settling would be ok if i meet soil bearing.
any ideas would be appreciated.
i'm not the original designer nor have i been to the site to check.
i'm thinking to wait if settling would stop, it still seems to be still supporting the pipeline.
if it continues then i'll replace it.
any options of preventing this foundation from settling further.
also shouldn't foundations really lean/settle a certain amount.
i only check soil bearing and assume settling would be ok if i meet soil bearing.
any ideas would be appreciated.






RE: options for spread foundation settling/leaning on 1 side
Also, vertical pipe supports often end up being spaced based on deflection criteria rather than stress. You've basically got a beam (the pipe) on spring foundations. If this one settles, load will shift away from it unless there's a large amount of flexibility in the piping system nearby. The fact that settlement stops doesn't mean that the support is actually functioning. It may mean that it's stopped settling because the load has all shifted elsewhere. The pipe /can't/ push the support down lower than the point it would settle to without the support, so you'll never see a gap open up (unless a cold case puts it under enough tension to pull some deflection out of it). Of course, this additional deflection and stress may or may not actually hurt the piping system.
Basically, what you have to do, and whether you even need to do it, is going to be heavily governed by the piping design.
RE: options for spread foundation settling/leaning on 1 side
RE: options for spread foundation settling/leaning on 1 side
are there any grout that i can use fill the gap between plate and concrete.
is steel shim plate the only option to fill the gap.
piping required a support at that location so i will put a support or fix that support regardless whether the pipe can span without that support.
RE: options for spread foundation settling/leaning on 1 side
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RE: options for spread foundation settling/leaning on 1 side
Honestly, even large pipe supports don't have a huge vertical loads on them compared to usual allowable ground pressures, nor does a plain footing. If anything, I tend to run into bearing pressure issues due to overturning from friction, but that type of failure doesn't really look like this. It also doesn't sound like you're having problems on the other supports. If this is a typical support, you'd expect other supports to act similarly if it were a systemic design problem. If you've had a reasonable amount of settlement in just this one spot it's likely due to poor ground prep, really bad ground conditions or something silly (installation on frozen ground). There could also be a systemic design problem, but it's likely something in combination with that if it is.
Alternately, it may have been installed with a screwed up elevation. Are you sure this is a new condition? As pipes get larger, the typical spacing is sometimes close enough together that your pipe won't always deflect to hit every support when they're built to standard construction tolerances. It's pretty common to have to come back and shim some supports in these cases.
Also, I'm assuming this pipe keeps going relatively straight and doesn't do anything like a hard vertical elbow that could result in liftoff in certain piping temperature cases.
My path forward would likely be to go and look at it and the adjacent supports to see if I could figure out what's going on. I'd also do the math to see what the bearing pressure looks like. What to do next depends on the timeline. If I wasn't sure of the cause and had some time, I'd start by having them shim the pipe the next time it's empty. Then watch over the next while to see if it settles more. If it does, then you get to do rehabilitation on the footing. That could be grouting, or excavating and extending the footing. You'll have a lot of flexibility in your methodology because the pipe obviously doesn't collapse when you remove the support. You won't have to maintain a load path during construction, which makes things much easier.
If you want to close the gap, steel shims are pretty typical for piping. You could use a bunch of different grouting techniques, though. If the gap gets really small, pressure grouting would work. Try not to inadvertently bond the shoe to the support, though.
(Sorry, this got a bit stream of consciousness on me)
RE: options for spread foundation settling/leaning on 1 side
I think SRE and TLHS have given you particularly good advice in their last two posts. Go slowly if you can and try to gain an understanding of what’s going on with the pipe support, and what’s causing the problem, what loads, what movements, etc. This will ultimately lead to a better solution and fix. I don’t think you know this right now. I would shim the gap btwn. the pipe and the support when the pipe is empty, so that you take pipe deflection out of the shimming process as much as possible. That is, maximize the gap to be shimmed, and the pipe loading after shimming if that is causing the support movement. I would also shoot some elevations on the four corners of the support and on the pipe over the support and at a couple equal distant points removed from the support. I would also take some horiz. control measurements to various points on the support and on the pipe, from control points unmoving and unrelated to the pipe and pipe support. You would like to see what’s moving and in which directions. If you can buy some time and really understand the problem, you almost always arrive at a better solution. Everyone else always wants quicker, and then be gone; that is, until the first guess didn’t do it, then it’s your fault, again.
RE: options for spread foundation settling/leaning on 1 side
Quick and cheap.
RE: options for spread foundation settling/leaning on 1 side