Ultimate top soil reaction [RVT]

Calculation of Ultimate top soil reaction

The soil range of importance for the Ultimate top soil reaction is from the ground level to the top of the pipeline.

Formula_RVT

Qp

Ultimate top soil reaction

Qn

Neutral top soil load

fm

Packing factor (averaged over range from ground level to top of pipeline)

H

Height of soil coverage on top of pipeline

D

Outer diameter of pipeline

Calculation of Reduced Ultimate top soil reaction

When taken into account the vault behaviour of soil for pipelines laid at large depths a reduced top soil reaction is calculated. A large depth is defined as a height of soil coverage on top of the pipeline greater then 8.6 times the outer diameter of the pipeline. The soil range of importance for the Reduced Ultimate top soil reaction is from ground level to the pipeline axis (this in contrast with the normal Ultimate top soil reaction, having a range of importance from ground level to the top of the pipeline).

Formula_rRVT

P'max

Reduced Ultimate top soil reaction

P'f

Formula_Pf

c

Drained cohesion (averaged over range from ground level to pipeline axis)

φ

For the NEN3650-1992 calculation methodology φ is simply defined as:

Angle of internal friction (averaged over range from 200 mm above pipeline to 200 mm below pipeline)

For the NEN3650-1:2012 calculation methodology φ is defined as:

Effective angle of internal friction (averaged over range from ground level to pipeline axis, using the Effective Young's modulus of soil for the same range with a depth as at top of pipe)

D

Outer diameter of pipeline

H

Height of soil coverage on top of pipeline

Q

Formula_Q

σ'o

Formula_SigmaO

G

Shear modulus (averaged over range from ground level to pipeline axis)

σk

Vertical grain pressure at pipeline axis (see General parameters)

σkh

Formula_Sigmakh


Last changed: 14/09/2016