Q1- A soil mass has a total unit weight of 17.2 kN/m and a saturation of ' 71 % The specific gravity of soil solid
is 2.71. Calculate the porosity and water content of the soil. What would be the weight of 3 m' of natural soil
and of saturated soil?

ANSWER:

1. porosity , n      = 0.4783 or 47.83%

2. water content, w         = 0.24  

3. W at 3 m³ volume        = 51.6 kN

Step-by-step explanation

SOLUTION:

GIVEN:

unit weight (total) = 17.2 kN/m3

S = 71%

G_s = 2.71

FIND:

1. porosity , n

2. water content, w

3. W at 3 m³ volume

PART 1 : porosity

γ=1+eGs?+Se?γw?

and

n=1+ee?

where,

γ = unit weight total

G_s =specific gravity of the solid

S = saturation

e = void ration

γ_w= unit weight of water

17.2=1+e2.71+(0.71)e?(9.81)

continue to solve for e to get:

e = 0.917

n=1+0.9170.917?

n = 0.4783 or 47.83%   ----> answer

PART 2 : water content, w

w=Gs?eS?

w=2.71(0.917)(0.71)?

w = 0.24   ----> answer

PART 2 : Weight at 3 m³ volume

γ=volumeweight?

W=γ×V

W=17.2kN/m3×3m3

W = 51.6 kN   ----> answer