A site investigation is the process of mapping the build-up, composition and bearing capacity of the soil at a building site, so that a safe and suitable foundation can be designed. It is a geotechnical investigation that gives advance insight into what lies below ground level.
Methods
A site investigation uses various techniques, often in combination:
- Cone penetration test — a cone is pushed into the ground and measures the resistance; this identifies the load-bearing layers
- Boring — a soil auger takes samples from various depths
- Monitoring well — for measuring the groundwater level
- Laboratory testing — determining properties such as compressibility, grain size distribution and permeability
Why is it needed?
A site investigation prevents surprises and damage during and after construction:
- Foundation design — determining at what depth load-bearing soil lies and whether piles are needed
- Settlement control — predicting settlement and tilting
- Excavation and dewatering — insight into groundwater and stability
- Risk reduction — avoiding costly extra work due to unknown ground conditions
Note the difference from an environmental soil investigation, which focuses on contamination of soil and groundwater, whereas a geotechnical site investigation concerns the engineering properties for the structure.
Related Terms
- Soil mechanics
- Geotechnics
- Soil auger
- Foundation
- Settlement
More guides and plans available at fredsdiyplans.com