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305Gurl

Burrow Pit problems

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Is there a simple systematic way to solve these types of problems. I am fairly decent solving phase diagrams problems, but these burrow pit problems comes in many different varieties and sometimes hard to grasp what is needed to solve the question asked. For example, some questions asked for the burrow volume required given fill volume needed; others asked for volume of water required to increase M.C., etc.

I always avoided understanding these problems, but this time I'm making a goal to try and be able to solve them.

Is there a specific strategy/approach that is constantly used to solve these problems? I would like to hear from the folks who actually mastered this subject area. Your assistance is greatly appreciated.

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There's never a quick and dirty, plug-and-chug way to solve these problems because they can vary. I think you just need to understand that soil has a different densities in situ versus in transit versus in place. If possible, you always want to solve for the dry unit weight and density at each phase. Moisture is the main variable that affects total density and volume.

Also, the term is "borrow", not "burrow". :)

Good luck!

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The most common theme in these problems is that the total mass (or weight) of soil solids remains the same - at the borrow pit, in transport and at the destination, regardless of the degree of compaction. Remember, that's soil solids ONLY, which is equal to the dry density x total volume (see sac_engineer' comment above)

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It could be "burro".

Seriously,a s said above you need to remember that the solids is always constant

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Burro ... what an ass :)

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Consider an embankment that has a volume of 200,000 cubic yards is to be

compacted to a dry unit weight of 108 pcf at a moisture content of 19%. The soil is to be

taken from a borrow pit wherein the soil has an insitu unit weight (total unit weight) of

122 pcf and a moisture content of 16%. Laboratory tests were performed and the

specific gravity, G = 2.68 was found.

What volume of soil must be taken out of the borrow pit to complete the

embankment? How much water must be added?

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Can anyone re-upload the pdf file?, I can not download it.

On other note, I have been reviewing few borrow problems and noticed that approach varies per author.

For transportation volume, some authors use Vs solids and others use Vt (Vs + Vs), so sometimes is confusing.

Linderburg in his CERM practice problems, in the same problem in part a he uses Vt for hauling purposes, however, in part b, he used Vs (Solids volume) only, (maybe because there is no more information?). Has anyone noticed this?

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Possibly  Vt is used in hauling because trucks are limited to a certain weight for legal weight on highways. Even offroad trucks are limited by weight,  the amount of cubic yards they can haul per trip can vary as the the total weight per cubic yard varies. This is sometimes the case when you are asked for the number truck trips required to provide x amount of cubic yards material at  certain moisture content.  

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