Is Gravel Backfill Lighter?
Is Gravel Backfill Lighter?
(OP)
Hi Folks,
I am designing a PWF and have a couple of questions regarding the backfilling.
In the Preservative Wood Foundation Design Specification, the average backfilling equivalent fluid pressure is given as 30psf/ft.
1) How's this number (30psf/ft) derived?
2) Is gravel only backfill lighter than average stable soil pressure?
Appreciate your response.
Thanks
I am designing a PWF and have a couple of questions regarding the backfilling.
In the Preservative Wood Foundation Design Specification, the average backfilling equivalent fluid pressure is given as 30psf/ft.
1) How's this number (30psf/ft) derived?
2) Is gravel only backfill lighter than average stable soil pressure?
Appreciate your response.
Thanks
RE: Is Gravel Backfill Lighter?
How was that number found? Well this subject has had numerous research projects and actual job measurements.
RE: Is Gravel Backfill Lighter?
Yes, gravel is generally "lighter" than most soils, simply because the volume of voids in gravel will typically be higher than the volume of voids in the same volume of soil, given the specific gravities of each are close.
RE: Is Gravel Backfill Lighter?
RE: Is Gravel Backfill Lighter?
RE: Is Gravel Backfill Lighter?
You are free to delete all your posts above that don't help a newcomer.
RE: Is Gravel Backfill Lighter?
How was that number found? Well this subject has had numerous research projects and actual job measurements. These sensors were mounted vertically and reading taken as fill was added. On one job of significant height, the sensors even recorded increased pressures when fill was added as far up as 30 feet above the gauge.
The sites were uniform sands, not compacted, but dumped backfill to concrete basement walls. Likely the same number would be for uniform gravel with near similar specific gravity. Likely included some natural water content.
Not giving actual numbers for the poster to use does not help him. My 50 is a ball park number since the data had considerable scatter.
RE: Is Gravel Backfill Lighter?
39 Field Measurements of Lateral Earth Pressures and Movements on Retaining Walls
I'd ignore useless arguments showing above.
RE: Is Gravel Backfill Lighter?
Edit: I'll add from one relatively recent Japanese study, this quote
Based on the new informations obtained from the tests, the design philosophy of a retaining wall is considered and it is proposed that a general retaining wall should be designed against the earth pressure at rest. .
RE: Is Gravel Backfill Lighter?
Is it a wall that is restrained, needing use of Ko?
Is it a cantilevered wall, needing use of Ka?
As usual, more info and/or a sketch would be helpful.
www.PeirceEngineering.com
RE: Is Gravel Backfill Lighter?