Geoscience Reference
In-Depth Information
Figure 8.1
Drainage capability of soils (after Sowers, 1979).
Table 8.2
Variability of permeability compared with other engineering mate-
rials (Cedergren, 1989).
Material
Permeability relative to soft clay
Soft clay
1
Soil cement
100
Concrete
1,000
Granite
10,000
High strength steels
100,000
8.3 Permeability based on grain size
•
The grain size is one of the key factors affecting the permeability.
•
Hazen Formula applied below is the most commonly used correlation for
determining permeability.
•
Hazen's formula appropriate for coarse grained soils only (0.1mm to 3mm).
•
Ideally for uniformly graded material with U
<
5.
•
Inaccurate for gap graded or stratified soils.
8.4 Permeability based on soil classification
•
If the soil classification is known, this can be a first order check on the permeability
magnitude.
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