Foundation Engineering / module 18
Laterally loaded piles
A cantilever into the ground — and the classification you must make before calculating anything.
What you will understand
- Classify a laterally loaded pile as rigid or flexible, and say why it must be done first
- Describe the two failure mechanisms and which one each classification produces
- Compute the lateral capacity of a short pile in clay and the effect of load eccentricity
- Explain why deflection normally governs a laterally loaded pile rather than capacity
Lessons
Rigid or flexible
Two mechanisms, and no way to tell which without checking.
Capacity and deflection
Which one actually sizes the pile.
Module summary
- The stiffness factor T = (EI/kh)^¼ sets the length scale; L/T decides the mechanism
- The example pile had T = 2.49 m: at 4 m long it was rigid, at 10 m flexible
- A short pile rotates and fails in the soil; a long pile hinges and fails in the pile
- Load height affects the applied moment; lateral resistance requires a verified equilibrium model
- Deflection at the head, not collapse, is what almost always sizes a laterally loaded pile
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 pile has EI = 190 852 kN·m² and sits in soil represented by a distributed line-spring stiffness kh = 5000 kN/m². What is the stiffness factor T, in metres?
Check yourself
What usually sizes a laterally loaded pile in practice?