﻿ Downward vertical soil stiffness [KLS]

# 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:

Clayey/peaty:

 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

NEN3650-1:2017

The NEN3650-1:2017 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:

Trench, Clayey/peaty:

Non-trench:

 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 l λ ν 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 Di Inner diameter of pipeline

Last changed: 10/30/2019