Volume of uncompacted soil material 1

[gegk]

Hi,
i would like help to solve this issue.
I have 78000 m^3 compacted soil (gravel and sand)from river deposit (embankent construction). Max Density 2,2 t/m^3
and loose density 1,67 t/m^3. I would like to find the uncompacted material that we excavate from borrow pit.
Thanks

 

[fattdad]

I'm not sure I fully understand your question. You have a pit to use for borrow. The borrow is a coarse-grained sand and gravel. It's in some natural dry density - maybe loose, maybe dense. Let's say the natural dry density is 2.0 t/m3, which would relate to 91 percent relative compaction.

You have a project where the earth fill will be placed in an engineered embankment. Let's say the target specification is 95 to 100 percent compaction, so we'll use 97.5%. That would equate to 2.15 t/m3 for the engineered density. For these conditions, for every 1 m3 that you excavate you'd get 0.93 m3 in the embankment.

Who cares about the density in the truck? Just how is that a relavent concept (i.e., maybe I'm missing something)?

f-d

¡papá gordo ain’t no madre flaca!

 

[Erdbau]

I think you are looking for the bulking factor.

Quick google search turned this up:

http://www.engineeringtoolbox.com/soil-rock-bulking-factor-d_1557.html

 

[civilman72]

fattdad - he may be trying to calculate number of truck trips for the project. Could be to generate preliminary project costs?

If that's the case, the swell factor is what needs to be calculated.

 

[Erdbau]

Exactly, Civilman. Swell factor a.k.a bulking factor.

 

[gegk]

Hi
and thank all for replies
I want to pay one subcontractor who constructed a embankment. The volume of embankment is 78000m3 but i must pay to him the material that he excaveted. Material is sand-gravel with MD(proctor) 2,2 t/m3 and loose density 1,67t/m3. So how much he excavate. He wants 78000*1,3 but i think is too big this value. Thanks

 

[bridgebuster]

In the future you should write your contracts to state payment is by m3 in place.

 

[fattdad]

I'm going back to my reply. The contractor wants to know how much he excavated and could care less what he placed. He may be digging 1 m3 to a loosely-placed pile (in the truck) of 1.3 m3. Then he uses it to fill a hole that's 1 m3. It wasn't in the ground at his truck density!

f-d

¡papá gordo ain’t no madre flaca!

 

[Erdbau]

I don't know. This all depends on how you said you were going to pay him. If the contract says that you were going to pay him for excavation by BANK CUBIC METER (the volume of soil in the ground before it was excavated), then you should only pay him for 78,000 m^3. If the contract says you were going to pay him by EXCAVATED CUBIC METER (the volume of soil as it bulks up and goes in the truck), then you should pay him 78,000 m^3 multiplied by a bulking factor. If the maximum dry density is 2.2 TCM, then it is unlikely that the in situ density is that high. In that case, you might be right that 1.3 is too much, because 2.2 TCM (maximum dry density) / 1.67 TCM (loose density) = 1.32 bulking factor. Maximum dry density from a proctor test is not the appropriate way to determine in situ density of the soil in place.

Find the in situ density of the material (sand cone, nuke, drive cylinder, etc.), and then divide THAT number by 1.67 TCM to find the bulking factor. But check your contract first to figure out what you are actually paying for.

 

[civilman72]

"but i must pay to him the material that he excaveted..." I think gegk needs to explain this better.

Previous replys are correct - it does depend on how the contract is written. The excavated material could be defined with the bulk density included. If this is case, I agree with everything Erdbau stated on how to calculate.

 

[gegk]

Thanks all of you for your answers. Erdbau answer was what i was looking for.