Effective Stress Method
The effective stress method allows us to calculate the vertical bearing capacity of an isolated pile in both undrained and drained soils. This method is suitable for drained conditions - i.e. conditions that prevail after sufficient time passed the construction.
The pile shaft resistance is given by:
where: | qs, j | - | shaft resistance in the jth layer |
βp,j | - | coefficients according to Bjerrum and Burland in the jth layer | |
σ0, j | - | average effective stress due to overburden acting along the pile in the jth layer | |
Asj | - | pile shaft area in the jth layer |
The pile base resistance is given by:
where: | qp | - | unit pile base resistance |
Ab | - | pile base area | |
Np | - | pile base resistance coefficient (according to Fellenius) | |
σp | - | effective stress due to overburden acting at pile base |