Downward vertical soil stiffness [KLS]

Calculations of Downward vertical soil stiffness

The soil range of importance for the Downward vertical soil stiffness is from the pipeline axis to 1.5 diameter under the pipeline axis.

NEN3650-1992

For the NEN3650-1992 calculation methodology two formula's are used to calculate the Downward vertical soil stiffness, one for sandy soil types and one for clayey/peaty soil types.

Sandy:
Formula_KLS_sandy

Clayey/peaty:
Formula_KLS_clayey2

kv

Downward vertical soil stiffness

Pwe

Sub-soil bearing capacity

D

Outer diameter of pipeline

cuo

Undrained cohesion (averaged over range from pipeline axis to 1.5 diameter below pipeline axis)

H

Height of soil coverage on top of pipeline

NEN3650-1:2012

The NEN3650-1:2012 calculation methodology uses the following formula's. There are two formula's for trench installation: one  for sandy soil types and one for clayey/peaty soil types and there is one formula for non-trench installation. A trench installation is either 1)Trench uncompressed fill or 2)Trench compressed fill and a non-trench installation is either 3)Boring or 4)HDD.

Trench, Sandy:
Formula_KLS_sandy_new

Trench, Clayey/peaty:
Formula_KLS_clayey_new

Non-trench:
Formula_KLS_nontrench

kv

Downward vertical soil stiffness

Pwe

Sub-soil bearing capacity

D

Outer diameter of pipeline

Eo

Effective Young's modulus calculated for range from pipeline axis to 1.5 diameter below pipeline axis, using depth at bottom of pipe (for Trench given in N/mm2, factor 0.5 is not dimensionless)

cuo

Undrained cohesion (averaged over range from pipeline axis to 1.5 diameter below pipeline axis) (given in N/mm2, factor 250 is not dimensionless)

m

Formula_KLS_m_new

l

Formula_KLS_l

λ

Formula_KLS_lambda

ν

Formula_KLS_nu

φo

Angle of internal friction (averaged over range from pipeline axis to 1.5 diameter below pipeline axis)

Epipe

Young's modulus of pipe material

Ib

Formula_KLS_Ib

Di

 

Inner diameter of pipeline


Last changed: 14/09/2016