BeginnerTopic 24 of 112Civil & Structural
Site investigation
Boreholes and tests determine soil and rock conditions.
In depth
Investigate boreholes, test pits, in-situ tests (SPT, CPT) and lab tests to determine soil profile, strength, groundwater and hazards. Desk study, walkover, then intrusive work; report gives parameters and recommendations. Poor investigation causes the majority of foundation problems.
Key points
- Number and depth of boreholes
- Disturbed and undisturbed samples
- Groundwater level
ExampleSPT N-values estimate sand density and bearing capacity.
What is Site investigation?
Boreholes and tests determine soil and rock conditions.
Why is it important to understand site investigation?
Site investigation finds the ground conditions before design, which prevents foundation failures and unexpected costs during construction.
Why is site investigation important?
Ground conditions are the most uncertain part of many projects, so investigation reduces the risk of unexpected problems and cost overruns.
What does a borehole provide?
Samples of soil or rock, groundwater levels and sometimes in-situ test results at different depths.
How is Site investigation used in practice?
Typical applications include drilling boreholes to find the depth of rock below a proposed bridge, taking soil samples for laboratory testing before choosing foundations and running a cone penetration test to assess the strength of loose sand.
What should I learn before Site investigation?
Study "Contours and maps" first (topic 23 of 112 in Civil & Structural). It covers the groundwork this topic builds on.
What are the key points of Site investigation?
Number and depth of boreholes. Disturbed and undisturbed samples. Groundwater level.
Can you give an example of Site investigation?
SPT N-values estimate sand density and bearing capacity.
What comes after Site investigation?
The next topic is "Building codes and standards", which builds directly on this one.
How difficult is Site investigation?
It is classed as Beginner in Civil & Structural (topic 24 of 112). It is an entry-level topic. It relies only on basic school mathematics and the ideas introduced earlier in this discipline.