Soils types are classified by their stability, and assigned a ‘soil class’. There are 6(7) soil classes, varying on moisture and movement in the soil:
A – Acceptable
S – Satisfactory
M – Moderate
H1 & H2 – Highly reactive
E - Extreme
P – Problem
It is essential to have a geotechnical engineer undertake a survey, and produce a report in order to accurately identify and classify the condition of the soil on site. This will then allow the structural engineer to recommend of a suitable footing system. Below is a table of common soil types, classification, and condition.
|
Type of Soil |
Soil Class |
Soil Condition |
|
Rock |
A |
Rock sites have no ground movement |
|
Sand |
A |
Sand has little or no movement |
|
Clay, slightly reactive |
S |
Slight ground movements due to moisture changes |
|
Clay, moderately reactive |
M |
Moderate ground movements due to moisture changes |
|
Clay, highly reactive |
H |
High ground movements due to moisture changes |
|
Clay, extremely reactive |
E |
Extreme ground movements due to moisture changes |
|
Problem |
P |
Sites which include soft soils, loose sands, landslip, mine subsidence, collapsing soils, erosion, fill and abnormal moisture conditions |
The type of soil can have implications of the footing/pier systems required to be used. A specialised engineering solution may increase the cost of construction.
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