waterline kickblock design
waterline kickblock design
(OP)
I've been asked by a civil engineer and municipality to provide criteria for design of kickblocks for water distribution pipes.
The question came up because the poor soils on the site likely don't have a bearing capacity of 3,000 psf and the public works department standard detail states "based on 3,000 psf soil bearing capacity".
The lateral forces caused by pipes and water hammers seems to have little to do with the concept of bearing capacity, and I would use a passive earth pressure and friction between concrete and soil approach.
Anybody encounter this before? I checked another municipality, and their standard detail states the same assumption about bearing capacity.
My preliminary calculations indicate that the friction component is relatively small compared to the passive earth pressure component. To have a capacity of 3,000 psf, for a burial of 5 feet, you would need a passive earth pressure equivalent fluid pressure of close to 600 pcf, or a passive earth pressure coefficient of close to 5, which not too many soils would have.
Any comments are appreciated.
The question came up because the poor soils on the site likely don't have a bearing capacity of 3,000 psf and the public works department standard detail states "based on 3,000 psf soil bearing capacity".
The lateral forces caused by pipes and water hammers seems to have little to do with the concept of bearing capacity, and I would use a passive earth pressure and friction between concrete and soil approach.
Anybody encounter this before? I checked another municipality, and their standard detail states the same assumption about bearing capacity.
My preliminary calculations indicate that the friction component is relatively small compared to the passive earth pressure component. To have a capacity of 3,000 psf, for a burial of 5 feet, you would need a passive earth pressure equivalent fluid pressure of close to 600 pcf, or a passive earth pressure coefficient of close to 5, which not too many soils would have.
Any comments are appreciated.





RE: waterline kickblock design
It does take a small amount of displacement before the full passive pressure is mobilized, so you should probably design for a decent FS, so the pipes aren't damaged by those small movements. I don't know what kind of movement the pipes can actually tolerate - may not be a serious issue if there is much of a FS.
I don't know why they would relate the block requirement to the bearing capacity either, unless that is a local empirical rule of thumb. Bearing capacity is, of course, not a nice simple number like 3000 psf for a given soil - it is a function of embedment depth and footing dimensions as well.
Bon Chance!
RE: waterline kickblock design
http://www.dipra.org/pdf/thrustRestraint.pdf that may be helpful in your efforts. I believe this particular manual/section has been around about a quarter century, but draws on decades of generally successful experience with similar methods before that time. Similar information, though instead for some different metric-sized pipes/readers is also available online from the link http://ww
I would caution that different types of piping material may involve different sizes of pipes and joining configurations that can affect magnitudes of thrust and other factors, and guidance from other sources is thus appropriate in those cases.
RE: waterline kickblock design
RE: waterline kickblock design
In actuality DIPRA (and for that matter AWWA in their manual M41), in talking about blocking for horizontal pipeline bends, it would appear maybe at least a little more appropriately actually clarifies this some for their readership (I suspect involving many disciplines) with an additional modifier as “horizontal” bearing strength. Unfortunately my old unabridged “Webster’s New International Dictionary” (I just measured at exactly 5.232” thick) didn’t include the modifier “vertical” in any of its several hundreds of words definitions of the word “bearing”!
RE: waterline kickblock design