Geotechnical Engineering

DHARM

24 GEOTECHNICAL ENGINEERING

Full saturation, S = 100%

Unit weight = ()

()

. (.. )
.

Ge.

e w

+

+

= +

1

280 065

165

γ 981 kN/m^3

= 20.51 kN/m^3.

Example 2.6: A sample of saturated soil has a water content of 35%. The specific gravity of
solids is 2.65. Determine its void ratio, porosity, saturated unit weight and dry unit weight.

(S.V.U.—B.E.(R.R.)—Dec., 1970)

Saturated soil

Water content, w = 35%

specific gravity of solids, G = 2.65

Void ratio, e = wG, in this case.

∴ e = 0.35 × 2.65 = 0.93

Porosity, n =

e

1 e

093

+ 193

=

.

.

= 0.482 = 48.20%

Saturated unit weight, γSat =

()

()

.

Ge

e w

+

1 +

γ

= (.. )

(.)

265 093.

1093

+ 981

+

×

= 18.15 kN/m^3

Dry unit weight, γd = G

e

. w
()

γ

1 +

= 265 981

193

..

.

×

= 13.44 kN/m^3.

Example 2.7: A saturated clay has a water content of 39.3% and a bulk specific gravity of 1.84.

Determine the void ratio and specific gravity of particles.

(S.V.U.—B.E.(R.R.)—May, 1969)

Saturated clay

Water content, w = 39.3%

Bulk specific gravity, Gm = 1.84

Bulk unit weight, γ = Gm .γw

= 1.84 × 9.81 = 18.05 kN/m^3

In this case, γsat = 18.05 kN/m^3

γsat =

()

()

Ge.

e w

+

1 +

γ

For a saturated soil,

e = wG

or e = 0.393 G

∴ 18.05 =

(. )

(. )

.(. )

GG

G

+

+

0 393

1 0 393

981