Geology Reference
In-Depth Information
decimal places) and some de
nitions
To convert from
To
Multiply by
LENGTH
inches
millimetres
25.4
feet
metres
0.30
metres
feet
3.28
kilometres
miles
0.62
miles
kilometres
1.61
AREA
square metres
square feet
10.76
9.29 × 10
−
2
square feet
square metres
VOLUME
cubic metres
cubic feet
35.31
cubic feet
cubic metres
0.02
0.001m
3
litres
cubic metres
cubic metres
litres
1,000
gallons (UK)
litres
4.55
litres
gallons (UK)
0.22
cubic metres
gallons (US)
264.17
cubic metres
gallons (UK)
219.97
Key volumetric parameters in soil mechanics are porosity, void ratio and specific volume.
The threekeycomponents insoilof aparticularvolume (
V
)arethevolumeofsolids(
V
s
) (i.e.mineral grains),
volume of voids between the solid particles (
V
v
) and the volume of water (
V
w
) within the voids.
V
=
V
s
+
V
v
.
POROSITY (n %) =
V
v
/
V
, i.e. the volume of voids as a percentage of the total volume of soil.
Someworkers prefer to use the closely relatedVOIDRATIO(e) =
V
v
/
V
s
. Conceptually, they are essentially
the same
as the soil is compressed the void volume decreases and the porosity and void ratio also decrease.
Incritical state soilmechanics,workers sometimes use the termSPECIFICVOLUME,which is de
-
nedas1+e.
Degree of saturation is the ratio of water volume to total voids. So SATURATION (
S
r
)=
V
w
/
V
v
expressed as a percentage. If all the voids are full of water,
S
r
is 100%.
WATER CONTENT is ratio of mass of water to mass of solid particles (
M
w
/
M
s
) so will vary according
to the speci
c gravity of the mineral grains, all other things being the same. These and other basic
de
nitions are clearly set out in most soil mechanics textbooks (e.g. Craig, 1992).
