Calculations of Ultimate horizontal soil reaction
The soil range of importance for the Ultimate horizontal soil reaction is from ground level to the bottom of the pipeline.
NEN36501992
For the NEN36501992 calculation methodology two formula's are given, one for sandy soil types and one for clayey/peaty soil types.
Sandy:
Clayey/peaty:
Qhor 
Ultimate horizontal soil reaction 
Kq 
Function of φ and H*/D 1 (for sandy soil types) 
σk 
Vertical grain pressure at pipeline axis (see General parameters) 
α 
constant: 0.6 
Kc 
Function of φ and H*/D 2 (for clayey/peaty soil types) 
cu 
Undrained cohesion (averaged over range from ground level to the bottom of the pipeline) 
φ 
Angle of internal friction (averaged over range from ground level to the bottom of the pipeline) 
H* 
Height of soil coverage from ground level to pipeline axis 
D 
Outer diameter of pipeline 
NEN36501:2017
The formula for sandy soil types is not changed in the NEN36501:2017 calculation methodology. For clay/peat soil types the NEN36501:2017 calculation methodology distinguishes slow and fast deformation. The formula's for clay are:
Clayey/peaty, slow deformation:
Clayey/peaty, fast deformation:
Qhor 
Ultimate horizontal soil reaction 
Kq 
Function of φ and H*/D 1 
σk 
Vertical grain pressure at pipeline axis (see General parameters) 
α 
constant: 0.6 for installation method trench and 1.0 for nontrench installation method. 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. 
Kcu 

Kc 
Function of φ and H*/D 2 
cu 
Undrained cohesion (averaged over range from ground level to the bottom of the pipeline) 
φ 
Effective angle of internal friction (averaged over range from ground level to the bottom of the pipeline, using the Effective Young's modulus of soil for the same range with a depth as at bottom of pipe) 
H* 
Height of soil coverage from ground level to pipeline axis 
D 
Outer diameter of pipeline 
1The function Kq is defined as:
Where: 

Kq∞ 

αq 

H* 
Height of soil coverage from ground level to pipeline axis 
D 
Outer diameter of pipeline 
Nc 
Function of φ 3 
d∞c 
Function of φ 4 
2The function Kc is defined as:
Where: 

K∞c 

αc 

Nc 
Function of φ 3 
d∞c 
Function of φ 4 
H* 
Height of soil coverage from ground level to pipeline axis 
D 
Outer diameter of pipeline 
3The function Nc is defined as:
4The function dc∞ is defined as:
Last changed: 10/30/2019