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NBN EN 1997-1 ANB

The NBN EN 1997-1 ANB standard determines the maximum pressure at the pile base (maximum resistance) pmax, base from the corresponding ith penetration test as follows:

where:

αp

-

pile base coefficient

εp

-

scale factor

β

-

expanded pile base coefficient

s

-

pile shape coefficient

qp

-

unit pile base resistance according to the De Beer method

The Scale factor εp is determined as follows:

- for tertiary OC-clay:

- for other soil types:

where:

Db,eq

-

equivalent pile base diameter

Dc

-

diameter of the CPT-cone

The maximum shaft friction (shaft resistance) pmax, shaft  is given by formula:

where:

αs, i

-

shaft friction coefficient in the ith layer

qs,i

-

average shaft friction in the ith layer

n

-

number of layers along the pile

Average shaft friction qs,i is determined as follows:

where:

qc,m,i

-

average cone resistance (qc) in the ith layer

ηpi

-

empirical friction coefficient

Empirical friction coefficient ηpi (or max. average shaft friction) are determined according to the soil type as follows:

Soil type

qc,m,i [MPa]

ηpi [-] or qs,i [kPa]

Clay

1 to 4,5

-

ηpi = 1/30

> 4,5

qs,i = 150

Silt

1 to 6

ηpi = 1/60

> 6

qs,i = 100

Sandy Clay

1 to 10

ηpi = 1/80

> 10

qs,i = 125

Sand

1 to 10

ηpi = 1/90

10 to 20

qs,i = 110+4(qc,m,i - 10)

> 20

qs,i = 150

Literature:

RICHTLIJNEN VOOR DE TOEPASSING VAN DE EUROCODE 7 IN BELGIË VOLGENS DE NBN EN 1997-1 ANB (WTCB Rapport nr. 20 - November 2020).

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