Foundation Engineering / module 1
What a foundation has to do
Two requirements, not one — and the second is usually what decides the size.
What you will understand
- State the two requirements every foundation must satisfy
- Explain why settlement usually governs the design of a foundation on clay
- Distinguish gross, net and effective bearing pressure, and say why net is the useful one
- Describe the load path from a column to the ground and where it can go wrong
Lessons
Two requirements, not one
Why a foundation that cannot fail can still be wrong.
Gross, net and effective pressure
What the ground actually feels, and why excavation is worth so much.
Module summary
- A foundation must not collapse and must not move too much; these are separate checks against separate limits
- Check both bearing resistance and settlement; either can govern, depending on the ground and the structure.
- Net pressure is what the ground actually feels as new load; gross pressure includes what was already there
- Excavating removes weight, so a basement can add far less net pressure than its gross weight suggests
- Foundations go deep when the ground near the surface cannot satisfy either requirement, not because deep is stronger
Teaching basis and review status
These are educational models and exercises. Check their assumptions before using the results. The full technical content and every diagram have not yet been independently verified.
Concrete and steel calculations retain their stated first-generation Eurocode teaching basis. Use the standards and amendments specified for your project; do not mix generations without an appropriate design basis.
Read the lesson register and outstanding review notesCheck your understanding
Check yourself
Which pair of soil properties governs the two foundation requirements?
Practice
A structure applies 210 kPa gross at a founding depth of 4.5 m in soil of unit weight 18 kN/m³. What net pressure does the ground feel, in kPa?