Buried Pipe Element (Underground Piping)

Property

Description

Submerged Pipe

Toggle on/off consideration of water buoyancy and change in physical and mechanical properties of soil suspended in water

Water height, H^w_s, H^w_e

Distance from pipe axis to soil water (in START-PROF 4.61 and lower, distance was calculated from the lowest insulation casing point!). Height can be negative or positive. Water height effects thrust force acting on the pipe (surfacing) and soil resistance to longitudinal and vertical pipe displacement  (soil properties change in water). More...
Water height is input only for analyses with SNIP 2.05.06-85. Heating networks cannot be placed on flooded sections (below soil water level).
Water height cannot change along the length for vertical elements; therefore, the difference in depth between the lower node H^w_s and the higher node H^w_e must equal the vertical projection, H^w_s - H^w_e = L. Elements with less than 1 degree slant from the vertical position are considered vertical.

Consider Soil Movements

Toggle on/off consideration of soil movements. Soil movement allows to model the effects of soil subsidence, frost swelling of soil, landslide, seismic soil movements

Soil Movement x,y,z

This feature is used to model soil subsidence (-Z direction), soil frost heave (+Z direction), landslide (any direction X,Y,Z), permanent ground deformation (any direction X,Y,Z), vertical or horizontal seismic fault crossing (any direction X,Y,Z) etc.

Soil spring movements in global coordinate system. Soil spring movements can change along the length of the pipe element. Its values is input at the start and end nodes of the pipe element. If soil movement is switched of on neighbor pipe element, then program model variable soil movements from values specified in current pipe to zero values at the end node of connected pipe element.

 More...

Backfill soil height, H_s, Н_e

Distance between soil surface and the highest insulation casing point. H = Z - (D_C / 2). When  H is input, Z is calculated automatically, and vice versa. For elements slanted from the horizontal position by more than 10 degrees, backfill height cannot be input.

Laying depth, Z_s, Z_e

Distance from soil surface to pipe axis. When  H is input, Z is calculated automatically, and vice versa.
Soil level cannot change along the length for vertical elements; therefore, the difference in depth between the lower node Z_s and the higher node  Z_e must equal the vertical projection, Z_s - Z_e = L. Elements with less than 1 degree slant from the vertical position are considered vertical.

Backfill soil number¹

Trench soil number, can be selected from the soil database (see note 1 below).

Base soil number¹

Base (undisturbed) soil number, can be selected from the soil database (see note 1 below).

Pipe laying type

If open trench type is chosen, then soil natural arch of collapse is not considered. The soil pressure on the pipe is calculated using whole depth.

If trenchless type is chosen (for example horizontal directional drilling), then soil natural arch of collapse is considered and soil pressure is calculated using the reduced depth according to the height of natural arch of collapse. Read more...

Insulation type²

Armopenobeton, polymer, polyurethane, other, no insulation. For polyurethane, insulation casing diameter  D_C and casing thickness S_C are selected automatically from the database based on pipe diameter  D. For other insulation types, these data must be input manually

Insulation casing diameter¹, D_C

External insulation casing diameter. Selected automatically by pressing , according to GOST 30732-2006 depending on insulation type. If diameter is changed, laying depth or backfill height is changed, depending on which value was input last.

If 0 (zero) value specified, then pipe outer diameter is used by default

Casing wall thickness¹, S_C

External insulation casing wall thickness. Selected automatically by pressing , according to GOST 30732-2006 depending on insulation type. For PPM insulation, casing thickness is input.

Factor NM

Factor NM accounting for the difference in the angle of friction of insulation-soil and metal-soil. Depends on external insulation layer material load properties.

Factor is determined according to:

• RD 10-400-01 table 5.3

• GOST R 55596-2013 table 8.3. If the pipeline is covered in a polyethylene wrap, friction factor  Nm can be reduced by 30%

• SNIP 2.05.06-85 in the absence of data, Nm=1.0

Recommended value for insulation with PE casing is NM=0.67, if insulation is absent NM=1.0

Presence of cushions

Determines whether or not to consider the presence of damping cushions. Please note that using damping cushions does not always increase the allowable axial expansion movement for buried pipelines, and may even reduce its function. Cushions cannot be input for elements slanted from the horizontal position by more than 10 degrees.