SOILS

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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