General parameters

Calculation of Vertical grain pressure at pipeline axis

The vertical grain pressure at pipeline axis is defined as:

Formula_SigmaK

The upper one is used if the freatic plane is not specified or below the pipeline axis. The bottom one is used if the freatic plane is above the pipeline axis level. Both formula's have a range from ground level to the pipeline axis.

σk

Vertical grain pressure at pipeline axis

γ*

(Mean) volume weight (averaged over range from ground level to pipeline axis)

H*

Height of soil coverage from ground level to pipeline axis

γ*1

(Mean) volume weight (averaged over range from ground level to freatic plane)

H*1

Height of soil coverage from ground level to freatic plane

γ*2

Volume weight (saturated) (averaged over range from freatic plane to pipeline axis)

H*2

Height of soil coverage from freatic plane to pipeline axis

γw

Volume weight of water

Illustration of properties for sigma k

Illustration of properties for sigma k

 

Calculation of Effective Young's modulus of soil

NEN3650-1:2012

The Effective Young's modulus of soil is calculated as:

Formula_Eeff

It is only used in the NEN3650-1:2012 calculation methodology and only for soil types classified as sand (gravel, sand and loam).

Eeff

Effective Young's modulus

E100

Young's modulus for an effective vertical grain pressure of 100 kPa (averaged over specified range)

σv

Vertical grain pressure at specific depth (given in N/mm2, factor 0.1 is not dimensionless)

 

Calculation of Effective angle of internal friction

NEN3650-1:2012

The Effective angle of internal friction of soil for a specific Effective Young's modulus of the soil is defined as:

Formula_phieff

It is only used in the NEN3650-1:2012 calculation methodology and only for soil types classified as sand (gravel, sand and loam). For the non-sand classified soil types the Effective angle of internal friction is the Angle of internal friction as supplied as soil type property.

φeff

Effective angle of friction

Eeff

Effective Young's modulus for a specific range and depth

The formula has different constants for the different sandy soil types. There is even distinction between clean, slightly silty and highly silty sand.

Gravel:
Formula_phieff_gravel

Sand, clean:
Formula_phieff_sand_clean

Sand, slightly silty:
Formula_phieff_sand_slightly_silty

Sand, highly silty:
Formula_phieff_sand_highly_silty

Loam:
Formula_phieff_loam


Last changed: 14/09/2016