Grain Size and Permeability

[DirtPlayer]

Anybody know better correlations between graine size distributions and coefficients of permeability?

 

[fattdad]

Here's a pdf of a correlation between D10 or D20 and permeability (notice that permeability is in units of 10^-4 cm/sec):

http://home.comcast.net/~fatt-dad/permeability_correlation.pdf

Hope this helps.

f-d

¡papá gordo ain’t no madre flaca!

 

[BigH]

I think that the best explanation/discussion that I have seen in texts available is given in Terzaghi & Peck's (with Mesri) book (1995). Normally, most have used D10 size (and Hazan's coefficient - although that was for uniform sized medium sand). Kenney's work at UofT suggests, if I remember right, that the D5 size might be a better fit for correlation. Of course, there are theoretical formulas as well. One item to keep in mind is the nature of your material. I have seen water ponding for three days on a crushed stone base course that was compacted to 100% modified Proctor MDD - yet, less than 8% was passing the #200 sieve. Rounded grains will have higher permeability than angular grains. But, suggest you start your look-see with TP&M. Cheers

 

[moe333]

There is a design method which uses the Karman-Kozeny equation to estimate permeability of granular soil based on the gradation, estimate of void ratio, and grain angularity. It was discussed in a paper in the ASCE Geotech. Journal a few years back and it estimated permeability much closer than the old Hazen formula. The paper provides guidelines for void ratio based on soil classification and relative density. I have it programmed into an excel gradation spreadsheet and it is also a good way to look at sensitivity with void ratio.