Split-spoon sampling
Split-spoon sampling
(OP)
Hi, I'm trying to solve this problem but i can't...
the following table gives the variation of the field standard penetration number (N60) in a sand deposit (then there's a table)
if the groundwater table is located at a depth of 6m, dry unit weight of sand from 0-6m is 18kN/m^3 and saturated from 6-12m is 20.2kN/m^3, and D50 is 0.6mm, estimate the variation of the relative density with respect to depth.
depth (m) N60
1.5 6
3.0 8
4.5 9
6.0 8
7.5 13
9.0 14
i know i have to use this equation:
Dr(%) = ([ N60(0.23+0.6/D50)^1.7)/9] [1/sigma prime knot/pa])^0.5 x (100)
My only question is that since there are multiple depths... how do i go about calculating it?
the following table gives the variation of the field standard penetration number (N60) in a sand deposit (then there's a table)
if the groundwater table is located at a depth of 6m, dry unit weight of sand from 0-6m is 18kN/m^3 and saturated from 6-12m is 20.2kN/m^3, and D50 is 0.6mm, estimate the variation of the relative density with respect to depth.
depth (m) N60
1.5 6
3.0 8
4.5 9
6.0 8
7.5 13
9.0 14
i know i have to use this equation:
Dr(%) = ([ N60(0.23+0.6/D50)^1.7)/9] [1/sigma prime knot/pa])^0.5 x (100)
My only question is that since there are multiple depths... how do i go about calculating it?





RE: Split-spoon sampling
I'd shy away from any formula with "precision" relationships. It just ain't that good a "testing" system in my view.
RE: Split-spoon sampling
What is the actual engineering problem that you're trying to address? Is this for pile design, earht pressure, etc.?
I'm pretty sure that if you are normalizing blow counts for the purposed of determining relative density you have to adjust for 1 tsf of confining pressure. Your OP doesn't address this however. . .
f-d
¡papá gordo ain't no madre flaca!
RE: Split-spoon sampling
It looks like it does adjust for confining pressure. [1/sigma prime knot/pa])^0.5 looks just like Cn for liquefaction assessment, since pa is almost exactly 1 tsf.