Shrink/swell factors for earthwork calculations
Shrink/swell factors for earthwork calculations
(OP)
I'm beginning to do earthwork calculations for site work. I'm performing the calculations on Terramodel and I was wondering about shrink/swell factors.
I typically just use 1.00 for the factors and compute a straight volume without factoring in shrink/swell. How are these shrink/swell factors incorporated into the modeling? Are these used to account for the compaction of fill?
I'm a little confused by this and I'm wondering if my modeling is not as accurate as it could be since I'm not incorporating the shrink/swell factors.
Any thoughts or suggestions on shrink/swell factors in earthwork (cut/fill) calculations?
Peace,
Stodds
I typically just use 1.00 for the factors and compute a straight volume without factoring in shrink/swell. How are these shrink/swell factors incorporated into the modeling? Are these used to account for the compaction of fill?
I'm a little confused by this and I'm wondering if my modeling is not as accurate as it could be since I'm not incorporating the shrink/swell factors.
Any thoughts or suggestions on shrink/swell factors in earthwork (cut/fill) calculations?
Peace,
Stodds





RE: Shrink/swell factors for earthwork calculations
Shrink/swell factors account for 1) how much will the material swell or "fluff" upon excavation (for use in computing how many bucketfulls/truckloads it will take to excavate and transport the material) and 2) how much will the swelled material shrink when compacted in-place.
I can't imagine that the program's help file doesn't include rough numbers to use for these quantities based on the soil type.
For cohesive soils, I would crudely estimate a shrink factor of 20-30%, with the swell factor maybe 5% larger. You should ask a professional estimator or conduct data gathering over several projects to refine the numbers.
Jeff
RE: Shrink/swell factors for earthwork calculations
RE: Shrink/swell factors for earthwork calculations
If there is no borrow, export or overhaul, do you really need the factor?
RE: Shrink/swell factors for earthwork calculations
RE: Shrink/swell factors for earthwork calculations
RE: Shrink/swell factors for earthwork calculations
RE: Shrink/swell factors for earthwork calculations
We never had a contractor complain about too much dirt, but in one particular area, where we'd allowed for a foot of topsoil (6" was the norm), we did get complaints about too little dirt. The upshot was that the retention basins (for once) were all more than adequately sized because that was where the contractor had got his dirt from.
RE: Shrink/swell factors for earthwork calculations
When excavating the rock you can get a pretty high expansion between 30% to 40% swell from in-place volume to loose volume. This will largely depend on excavation method. Blasting will result in less swell unless the blasting pattern is very tight.
The silt/clay overburden soils will swell from around 15% to 20% from in-place volume to loose volume.
Shrinkage factors will be on the order of 5% to 10% going from loose volume to in-place for clay and 15 to 20% for rock. These are negative values.
These are just ranges and I would not hold me to these numbers.
Engineering is the practice of the art of science - Steve
RE: Shrink/swell factors for earthwork calculations
RE: Shrink/swell factors for earthwork calculations
RE: Shrink/swell factors for earthwork calculations
RE: Shrink/swell factors for earthwork calculations