Calculation of Neutral top soil load
The soil range of importance for the Neutral top soil load is from ground level to the top of the pipeline.
Qn 
Neutral top soil load 
γ 
(Mean) volume weight (averaged over range from ground level to top of pipeline) 
H 
Height of soil coverage from ground level to top of pipeline 
γ1 
(Mean) volume weight (averaged over range from ground level to freatic plane) 
H1 
Height of soil coverage from ground level to freatic plane 
γ2 
Volume weight (saturated) (averaged over range from freatic plane to top of pipeline) 
H2 
Height of soil coverage from freatic plane to top of pipeline 
γw 
Illustration of properties for neutral topsoil load
Calculation of Real top soil load
The Neutral top soil load table can either be filled with neutral or real top soil load values, depending on the chosen option for the Neutral top soil load in the Advanced Calculation Options. The soil range of importance for the Real top soil load is the same as for the Neutral top soil load, which is from ground level to the top of the pipeline.
NEN36501992
The NEN36501992 calculation methodology uses the following formula.
Qk 
Real top soil load 
Qn 
Neutral top soil load 
fk 
Shrinkage factor 1 
Qp 
1The shrinkage factor is defined as:
Qp 

Qn 
Neutral top soil load 
μ 
Shrinkage percentage (averaged over range from ground level to top of pipeline) 
D⋅kvmin 
Shrinkage pressure (averaged over range from ground level to top of pipeline) 
NEN36501:2017
For the NEN36501:2017 calculation methodology the formula used is:
Qk 
Real top soil load 
Qn 
Neutral top soil load 
μ 
Shrinkage percentage, if the installation method is trench compressed fill, the shrinkage percentage compressed is used instead (averaged over range from ground level to top of pipeline) 
D 
Outer diameter of pipeline 
kv,top 

Qp 

zmax 

kv 

kbuis 

Epipe 
Young's modulus of pipe material 
Iw 

ky 
Dimensionless deflection coefficient, a value of 0.1 is used 
Dg 
Averaged diameter of pipeline 
t 
Wall thickness 
Last changed: 10/30/2019