Foundation Engineering / module 2
Choosing a foundation
Shallow, deep, or change the ground — and how the choice is actually made.
What you will understand
- Decide, in outline, when a shallow foundation is no longer the sensible answer
- Estimate the depth of ground a foundation actually stresses, and use it to judge which layers matter
- Explain why a deep foundation is not simply a stronger version of a shallow one
- Recognise ground improvement as a third option rather than a last resort
Lessons
How deep does a foundation reach?
The stressed volume decides which layers you have to care about.
Shallow, deep, or improve the ground
Three options, and the questions that choose between them.
Module summary
- A foundation stresses roughly 1.5 to 2 times its width below founding level; layers below that rarely govern
- The stressed depth scales with the foundation, so a raft can be troubled by a soft layer a pad never notices
- Piles are chosen to reach better ground or to control settlement, not because they are inherently stronger
- Ground improvement changes the soil rather than the structure, and is often cheaper than either alternative
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
Practice
A 5 m square raft is founded at 2 m depth. Using an influence depth of 2B, how far below EXISTING GROUND LEVEL does the significantly stressed zone extend, in metres?
Check yourself
Which statement about piles is correct?