Buried Pipe Element (Underground Piping)

Property

Description

Submerged Pipe

Enable/disable water buoyancy effects and changes to soil properties when saturated

Water height, H^w_s, H^w_e

Vertical distance from pipe centerline to water table. Accepts positive or negative values. Affects buoyancy forces (pipe flotation) and soil resistance to longitudinal/vertical movement (due to property changes in saturated soil). More...
Water height input applies only to analyses using SNIP 2.05.06-85. Heating networks cannot be placed below groundwater level.
For vertical elements, water height must be constant. The difference between lower node H^w_s and upper node H^w_e must equal the vertical projection: H^w_s - H^w_e = L. Elements within 1 degree of vertical are considered vertical.

Consider Soil Movements

Enable/disable soil movement effects. Use to model soil subsidence, frost heave, landslides, seismic displacements, or permanent ground deformation

Soil Movement x,y,z

Models soil subsidence (-Z), frost heave (+Z), landslides (any X,Y,Z direction), permanent ground deformation, or seismic fault crossings. Define soil spring displacements in the global coordinate system. Values can vary along the element length - input at start and end nodes. If adjacent elements have soil movement disabled, the program gradually transitions from specified values to zero at the connection point.

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Backfill soil height, H_s, H_e

Distance from ground surface to top of insulation casing. H = Z - (D_C / 2). When H is specified, Z calculates automatically, and vice versa. Not applicable for elements angled more than 10 degrees from horizontal.

Laying depth, Z_s, Z_e

Distance from ground surface to pipe centerline. When H is specified, Z calculates automatically, and vice versa.
For vertical elements, burial depth must be constant. The difference between lower node Z_s and upper node Z_e must equal the vertical projection: Z_s - Z_e = L. Elements within 1 degree of vertical are considered vertical.

Backfill soil number¹

Trench backfill material. Select from the soil database (see note 1 below).

Base soil number¹

Native (undisturbed) foundation soil. Select from the soil database (see note 1 below).

Pipe laying type

Open trench method: soil arching is ignored. Soil pressure calculations use full trench depth.

Trenchless method (e.g., directional drilling): accounts for soil arching. Soil pressure calculations use reduced depth based on natural arch height. Read more...

Insulation type²

Armopenobeton, polymer, polyurethane, other, or no insulation. For polyurethane, casing diameter D_C and thickness S_C auto-populate from the database based on pipe diameter D. For other insulation types, enter these values manually.

Insulation casing diameter¹, D_C

External insulation casing OD. Auto-populates via per GOST 30732-2006 based on insulation type. Changing diameter updates burial depth or backfill height (whichever was entered last).

Enter 0 to use pipe outer diameter as default.

Casing wall thickness¹, S_C

External insulation casing wall thickness. Auto-populates via per GOST 30732-2006 based on insulation type. For PPM insulation, enter thickness manually.

Factor NM

In Aynbinder's model: accounts for friction angle differences between insulation-soil and metal-soil interfaces. Depends on external insulation material load characteristics.

Determine factor per:

• RD 10-400-01 table 5.3

• GOST R 55596-2013 table 8.3. For polyethylene-wrapped pipelines, reduce friction factor NM by 30%.

• SNIP 2.05.06-85 defaults to NM=1.0 if no data available.

Recommended: NM=0.67 for PE casing insulation, NM=1.0 for bare pipe.

In ASCE 2001 model: NM equals factor f - coating factor relating soil internal friction angle to soil-pipe interface friction angle.

In EN 13941 model:

Expansion cushions

Enable/disable damping cushion effects. Note: cushions don't always increase allowable axial movement and may reduce functionality in some cases. Not available for elements angled more than 10 degrees from horizontal.