A new face drilling rig for narrow tunnels and ... - Advanced Mining

Pic. 1:
Multi-phase system of the soil [3]
Pic 2:
Porosity, void ratio and
degree of saturation
Grain size and grain size composition
The grain size and the composition of the grain size,
respectively, determine the classification of soil. In picture
3 the grain size groups clay, silt, sand, gravel and stone, as
well as upper and lower grain size limits are shown.
In order to determine the composition of grain sizes,
basically two methods are used, i.e. screen analysis and
hydrometer analysis.
SCREEN ANALYSIS:
EDUCATION
One of the methods most widely used for determining
particle size distribution is the screen analysis. The screen
analysis is suitable for non-cohesive soil with grain sizes
of 0,0063 mm to 125 mm. The soil to be examined is dried
and later divided into grain size groups by mesh screens or
quadratic-perforated screens. The mesh size corresponds
to a standardized size grading (screen array). The grain
sizes are ascertained by the nominal width of the screens,
which they have last passed. Picture 4 shows the screens
of a screen analysis, with mesh widths of 16 mm, 8 mm, 4
mm, 2 mm, 1 mm, 0,25 mm and 0,125 mm.
Issue 04 | 2010 www.advanced-mining.com
Type
< fine grain or Clay
Sand
gravel
spectrum of grain
size in mm
≤ 0,002
fine- > 0,002 - 0,006
U
middle- 0,006 - 0,02
gross- 0,02 - 0,06
> 0,06 - 2
fine- 0,06 - 0,2
S
middle- 0,2 - 0,6
gross- 0,6 - 2
> 2 - 63
fine- 2 -63
G
middle- 6,3 - 20
gross- 20 - 63
Stone X > 63
Pic. 3:
Grain size groups [6]
5