Question

Soil technology
@ASH90 see comments below.

Answer 1

Your original question:
hi, no it's not a lab it's kind of like how we did the others but this one seems to be a bit different because on the last one we did not have to find a moist unit weight but with this one i do.

So could you please check what i have as my answers for these to see if i got them correct?

For a given soil sample, the moist soil sample has a volume of 0.25 ft 3 and weighed 30.75 lbs moisture content (w)= 9.8% and apparent specific gravity (Gs)= 2.66 determine a moist unit weight.
V= Volume
(W)= Moisture content
(Gs)=Specific gravity
W=Weighed
-------------------------------------------------------
(a) moist unit weight=123 lb/ft^3
(b) dry unit weight= 112lb/ft^3
(c) void ratio=0.48
(d) porosity=.324

Answer 2

My reply (your answers are all correct)
(a) moist unit weight: correct as you had it.
Moist unit weight = \(Ww/vol=30.75/0.25 lb/ft63\)

(b) dry unit weight \(\gamma_d\) : correct as you had it.
Moisture content
W=\(\dfrac{\gamma_w-\gamma;_d}{\gamma_d}\times 100%\)
so
\(\gamma_d = \dfrac{\gamma_w}{1+W}\)
\(= 123/(1+0.098)\)
\(= 112.0~~lb/ft^3\)

(c) voids ratio = 0.484 as you had it
To find voids ratio, we can draw the phase diagram of the wet
soil / cubic foot

air water solid total
************|****************|*************|*****************
W 0 11 112 123 lbs

V 0.149 11/62.4 112/(2.66*62.4) 1.0 c.f.
=0.176 = 0.674

Vv = volume of voids (per cubic ft) = 0.149+0.176 = 0.325
Voids ratio = Vv/Vs = 0.326/0.674 = 0.484

(d) porosity (almost) the same as you had it.
porosity n = Vv/Vt = .326 / 1 =0.325

Answer 3

@mathmate thanks for checking it. Since you have helped me out so much I have become better at these types of problems as you can see. Thanks again for being a great help.

Answer 4

@ash90
Like everything else, a little practice helps a lot, and that works for me too! :)