Porosity and Degree of Saturation

n = \frac{e}{1 + e}, S = \frac{V _{w}}{V _{v}}, S e = w G_{s}

Porosity n = Vv/V is related to void ratio by n = e/(1+e). Degree of saturation S = Vw/Vv equals 1 (100%) when all voids are water. The identity S e = w Gs links gravimetric water content w = Ww/Ws to the phase volumes. Gs is specific gravity of solids.

$n$: Porosity
$S$: Degree of saturation
$w$: Water content Ww/Ws
$G_{s}$: Specific gravity of solids
$e$: Void ratio

Step-by-step solved example

e = 0.60, w = 0.18, Gs = 2.70. Find n and S.

n = e/(1+e), S e = w Gs.

1. Porosity
n = e/(1+e) = 0.60/1.60 = 0.375.
$n = 0.375$
2. Saturation
S = w Gs / e = 0.18×2.70 / 0.60 = 0.486/0.60 = 0.81 (81%).
$S = 0.81$

Answer: n = 0.375, S = 0.81

10 practice questions

0/10 correct

1.For e = 0.50, porosity n is

2.Fully saturated soil has S =

3.The identity Se = w Gs with S = 1, Gs = 2.65, e = 0.53 gives w nearest

4.n is always

5.If n = 0.40, then e =

6.Water content w is

7.A dry soil has S =

8.Gs of quartz sand is typically about

9.If w = 0.10, Gs = 2.70, e = 0.45, S equals

10.Porosity n equals Vv divided by