Question

The relationship between γ and γd can e derived when the degree of saturation is______

(a) 0

(b) 0.5

(c) 0.8

(d) 1

The question was posed to me in an interview.

This interesting question is from Functional Relationships in division Preliminary Definitions and Relationships of Geotechnical Engineering I

Answer 1

Right option is (a) 0

The explanation is: The bulk unit weight is given by,

γ = \(\frac{(G+e)S γ_w}{(1+e)}\)

When the degree of saturation S=0,

the unit weight is \(\frac{(G+e) γ_w}{(1+e)}\) which is equal to γd

 ∴ \(γ_d = \frac{Gγ_w}{(1+e)}\)

When the degree of saturation S=1,

the unit weight is \(\frac{(G+e) γ_w}{(1+e)}\) which is equal to γsat

∴ \(γ_{sat}=\frac{(G+e) γ_w}{(1+e)}\).