Analysis According to EA-Pfähle
The load-settlement curve of a single pile is constructed in the following way:
1) The shaft bearing capacity Rs,k is determined as follows:
- for bored and CFA piles
- for driven piles
where: | qs,k,i | - | shaft resistance in i-th layer [kPa] |
As,i | - | shaft area in i-th layer [m2] | |
ssg,ssg* | - | settlement at shaft resistance activation | |
ηs | - |
subsequently, the settlement condition is assessed:
- for bored and CFA piles
- for driven piles
where: | ssg,ssg* | - | settlement at shaft resistance activation [mm] |
Rs,k | - | shaft bearing capacity for settlement ssg resp. ssg* [MN] |
If condition does not satisfy, the load curve cannot be constructed.
2) The base bearing capacity Rb,k is calculated in required levels of s/D:
- for bored and CFA piles
- for driven piles
where: | qb,k | - | base resistance in level s/D resp. s/Deq [kPa] |
Ab | - | base area [m2] | |
ηb | - | ||
s | - | settlement | |
D,Deq | - | base diameter |
3) The total pile resistance Rc,k is given by:
where: | Rs,k | - | shaft bearing capacity for limit settlement sg [kPa] |
Rb,k | - | base bearing capacity for limit settlement sg [kPa] | |
sg | - | limit settlement 0,1D resp. 0,1Deq |
The pile bearing capacity is assessed for compressive loads. The pile loaded by tensile loads is not verified.
The pile verification is carried out according the theory of limit states:
where: | Rc,d | - | design value of total bearing capacity |
Rc,k | - | characteristic value of total baring capacity | |
γt | - | partial factor on total resistance of pile | |
Vd | - | extreme vertical load acting on a pile | |
Wp | - | pile self-weight |
Literature:
German Geotechnical Society: Recommendations on Piling (EA-Pfähle). Berlin: Ernst & Sohn, 2012.