The soil with the greatest porosity would have?

Question

A. round particles of different sizes.
B. round particles of the same size.
C. angled particles of different sizes.
D. angled particles of the same size.

Answer 1

b

There would be the largest spaces between particles. Angled particles or multi-size particles could combine to fill in the spaces between.

Note about answer C: Porosity relates to the amount of space between particles. Imagine a box of tennis balls. Pour in some ping pong balls or marbles or angular rocks, shake it around, and there will be room for more than the tennis balls once it settles (reducing porosity, or space/volume between pieces). But if you've filled the box with as many tennis balls as will fit, you can't add more tennis balls. The "all tennis balls" idea is also described as well-sorted particles. Angular particles WILL fit together, particularly when poorly sorted (multiple sizes) - small particles fill in the empty spots between the big ones.

Answer 2

The answer is B, I know because I deal with Porosity every day in my job. If there are different sized particles they can fit inside the porespace left by the larger particles.

The key word is tessellation or how well different objects fit together. With a well sorted (equal grainsize) sediment you can get porosities up to 40%. any irregularities or inequalities in the grainsize bring down the porosity.

Answer 3

b

if they're different sizes, then the small particles can fit in the gaps that the big ones leave. huge round cobbles almost always have sandy soil in the gaps when encountered in Quaternary terrace deposits. imagine if there was no soil and just huge round cobbles -- super porosity.

also, in practice uniform 3/4" diam. angular crushed rock is used for drainage structures. many contractors i've worked with would rather use 3/4" diam. round river rocks, but the cost is prohibitive.

this is from moderate amounts of experience in the geotechnical engineering field. i am a professional geologist, though that doesn't mean i know this answer with an absolute certainty.

Answer 4

INFOPOTAMUS is absolutely correct!!!!

THE ANSWER IS B!

The highest porosity is obtained when the, lets use marbles, are lined up in straight lines, exactly on top of each other in the x, y, ans z directions. Think of marbles in a clear box. If you can get them to line up in a straight matrix, the porosity is the highest.

BTW - ADUMU - Do your own homework buddy!

Edit: See source - the correct answer is still B

Also, the maximum obtainable porosity with cubicly packed, perfectly round spheres (regardless of size) as described above is 47.6%

- from "Geology of Petroleum" by A. I. Levorsen, H. W. Freeman and Company, 1967, p.113.

Answer 5

C. angled particles of different sizes.

bacause the more consistent the shape and size, the more chance of the particles joining together like a 'team' and become more compact, hence become less porous and become its more difficult for, lets say, water to pass through... so, irregular angled particles of various sizes offer the least form of compactness and are thus, most porous....

Answer 6

C, this configuration leads to the least efficiently packed particles

Answer 7

Answer - D.