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Soil Mechanics and Foundation Engineering - Engineering

Q1:

If dry density, water density and specific gravity of solids of a given soil sample are 1.6 g/cc, 1.84 g/cc and 2.56 respectively, the porosity of the soil sample, is

A 0.375

B 0.370

C 0.380

D 0.390

ANS:A - 0.375

As we take the given value of water density then the answer will come porosity(n) =0.66 by giving confusion of water density the answer will come wrong, for correct answer yo can take water density =1g/cc.

Yd=((G*Yw)/(1+e)),
Yd= 0.6,

n = e / 1+e = 0.375. rd=1.6g/cc ,r=1.84g/cc relation is rd=r/1+w.
We get water content w= 0.15. Dry density = (Gs*water density)/1+e.
Water density = 1 g/cm^3.
1.6 = (2.56*1)/1+e,
e = 0.6,
n = e/1+e,
n = 0.375.