Preventing settlement from MSE Wall?
Preventing settlement from MSE Wall?
(OP)
Good day!
I am designing 8m high MSE Wall. There is a 0.6m diameter high pressure water supply pipe 1.2m below NGL, along the wall alignment. What could be done to prevent any settlement from the MSE Wall?
I am designing 8m high MSE Wall. There is a 0.6m diameter high pressure water supply pipe 1.2m below NGL, along the wall alignment. What could be done to prevent any settlement from the MSE Wall?
RE: Preventing settlement from MSE Wall?
RE: Preventing settlement from MSE Wall?
MSE walls with Georgrid layers, typically the layers at the top of the wall don't need to be as long as the layers at the base of the wall. You could maintain a constant geogrid length for the total height of the wall.
RE: Preventing settlement from MSE Wall?
In short, there's already 1.2m soil on top of the pipe, and an additional 8m would be added. Should the pipe be encased or is there another way to prevent settlement?
RE: Preventing settlement from MSE Wall?
There are things you can do to prevent settlement, like support the pipe on piles etc but these may be a bit extreme.
Concrete encasing the pipe will not prevent settlement, just stiffen the pipe section.
If its a short section of pipe, say 40m, I would replace the section of pipe with a HDPE pipe. Specify a pipe with a low Standard Dimension Ratio (SDR, which means a thick wall compared to diameter) HDPE pipes are more flexible than traditional concrete pipes and can absorb settlement better. Place a manhole either side of the embankment and use a flexible connection at the manholes.
RE: Preventing settlement from MSE Wall?
RE: Preventing settlement from MSE Wall?
www.PeirceEngineering.com
RE: Preventing settlement from MSE Wall?
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RE: Preventing settlement from MSE Wall?
One could elaborate on this by doing the loose backfill part and then, on the original surface place a wide concrete slab to transfer loads from directly over the pipe to wide adjacent ground, and placing compressible material such as corn stalks as backfill. That would even out the settlement and only require a gradual transfer of this treatment gradually to non-treated areas.
RE: Preventing settlement from MSE Wall?
As PEinc says piles/ground imporovment are options, might be expensive but it's a 0.6m water pipe so it's might/probably be warranted. Pulling shouldn't require removal of the pipe and they may need to be bored piles sue the potential effects from driving vibrations.
Stone Columns may not require the removal of the pipe either.
If it's both public infrastructure , it may be a lot easier to get funding for a robust solution.
RE: Preventing settlement from MSE Wall?
pile support the reinforcement zone in proximity to the pipe.
then again, you could just move the pipe!
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ípapß gordo ainÆt no madre flaca!
RE: Preventing settlement from MSE Wall?
Thanks!
RE: Preventing settlement from MSE Wall?
RE: Preventing settlement from MSE Wall?
Realignment is good considering maintenance issues but can be costly since right of way extension might be needed.
I would consider lightweight fill if it can resist collision and seismic forces.
For the meantime, is there a good reference or sample calculations for imperfect ditch and stone columns?
Will suggest every possible solution to client at next meeting and let them decide.
RE: Preventing settlement from MSE Wall?
The settlement assessment of stone columns is pretty empirical for the most part. You need to determine the amount of settlement without stone columns first (i.e. settlement from the MSW wall) and then the settlement improvement factor (n) with stone columns in place, which is based on the replacement ratio - area of stone column (Ac) to area of soil/untreated ground (As).
For example you may have pre-stone column settlement of 85mm. Your assessment indicates an improvement factor of 2.2. Therefore your settlement will be 85/2.2 = 39mm.
See link below for further information, a google search should bring up enough information for a starting point. Sorry cant be of more help as I am swamped at the minute..
http://userweb.eng.gla.ac.uk/MScPosters2014-15/Eng...
RE: Preventing settlement from MSE Wall?
www.PeirceEngineering.com
RE: Preventing settlement from MSE Wall?
Use of styrofoam as lightweight fill has been used in a number of locations around the world - Utah's I-5 (or is it I-15) used it. Issues include fire - but you would need to surround the styrofoam by fill (on top); on the sides you could easily "hang" siding on the styrofoam - make it look like a MSE wall. Check Horvath at Manhatten University for references and papers. Elastizel is another possible solution.
As for MSE - we had a problem once when the culvert supported on piles was skewed to the roadway embankment's MSE wall . . . the strips were perpendicular to the wall - as is normal; but they went under some weird deformation due to the culvert's non-settlement where the embankment underwent major settlement (and yes, slip joints were used on the walls face at the culvert's ends - but this did no good for movement inside the reinforced mass due to the skew.
A lot depends on the nature of the ground on which you are building the fill. OG's sage advice, coupled with other ideas - but as some say - moving it might be best. Who is responsible for repair of the pipe in years down the line??
RE: Preventing settlement from MSE Wall?
www.PeirceEngineering.com
RE: Preventing settlement from MSE Wall?