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Pile CPT 

GEO5

Geotechnical software

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Pile toe coefficient ALFA p

The pile toe coefficient of capacity reduction αp identifies the type of pile. Its values are determined from one of the available calculation methods or they can be entered manually by the user. For NEN 6743 a EC 1997-2 methods the following built-in values of the coefficient αp are available:

Piles αp [-]
prefabricated driven piles or steel piles 1,0
Franki pile 1,0
driving wooden pile 1,0
Vibrating 1,0
cast in place screw piles 0,9
prefabricated screw pile 0,8
cast in place screw piles with additional grouting 0,9
prefabricated screw pile with additional grouting 0,8
steel tubular piles 1,0
continuous Flight Auger (CFA) 0,8
bored piles or piles sheeted by bentonite suspense 0,5
bored piles with steel casing 0,5

For LCPC and Schmertmann the coefficient is back-calculated based on the value of penetration resistance qc (the values are stored in the following table):

Orientation values of the pile toe coefficient αs based on the cone tip resistance qc

LCPC (Bustamante) Soil type Cone stress (tip resistance)
qc [MPa] 		αp

for bored piles 		αp

For driven piles
Jíl < 1 0,04 0,50
1 <  qc  < 5 0,35 0,45
5 < qc 0,45 0,55
Písek qc < 12 0,40 0,50
13 < qc 0,30 0,40

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