Calculations of Upward vertical soil stiffness
NEN36501:2017
The Upward vertical soil stiffness is only calculated for the NEN36501:2017 calculation methodology. The soil range of importance for the Upward vertical soil stiffness is from ground level to the top of the pipeline. 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 nontrench installation. A trench installation is either 1)Trench uncompressed fill or 2)Trench compressed fill and a nontrench installation is either 3)Boring or 4)HDD.
Sandy:
Clayey/peaty:
Nontrench:
kv,top 
Upward vertical soil stiffness 
Qp 

E 
Effective Young's modulus calculated for range from ground level to the top of the pipeline, using depth at top of pipe (given in N/mm2, factor 0.2 and 0.25 are not dimensionless) 
D 
Outer diameter of pipeline 
H 
Height of soil coverage on top of pipeline 
m 

l 

λ 

ν 

φt 
Angle of internal friction (averaged over range from ground level to the top of the pipeline) 
Epipe 
Young's modulus of pipe material 
Ib 

Di 
Inner diameter of pipeline 
The formula for kv,top has been adapted for the calculation model used in Ple4Win, also see the comment on page 134, NEN36501:2017, C.4.3.2.
Last changed: 10/30/2019