Pipe-soil friction [F]

Calculations of Pipe-soil friction

The soil range of importance for the pipe-soil friction is from 200 mm above to 200 mm below the pipeline.

NEN3650-1992

The following equation is used to calculate the pipe-soil friction:

Formula_F

W

Pipe-soil friction

φ

Angle of internal friction (averaged over range from 200 mm above pipeline to 200 mm below pipeline)

σk

Vertical grain pressure at pipeline axis (see General parameters)

δ

Angle of pipe-soil friction (averaged over range from 200 mm above pipeline to 200 mm below pipeline)

a

Adhesion 1

 

1The adhesion is defined as:

Sandy:
Formula_Adhesion_sandy

Clayey/peaty:
Formula_Adhesion_clayey2

c'

Drained cohesion (averaged over range from 200 mm above pipeline to 200 below pipeline)

NEN3650-1:2012

For the NEN3650-1:2012 calculation methodology the Adhesion is multiplied by 0.6.

The φ is calculated as the Effective angle of internal friction (averaged over range from 200 mm above pipeline to 200 mm below pipeline, using the Effective Young's modulus of soil over the same range for a depth of the pipeline axis).

In case of an HDD (Horizontal Directional Drilled) pipeline part, the pipe-soil friction is set to zero (and the displacement at maximum soil friction is set to 8 mm).


Last changed: 20/10/2016