Soil type properties

Soil name:

Identity name of soil type

Required

Soil type:

Main soil type: Gravel, sand, loam, clay or peat

Required / Prescribed name

(Calculation of Horizontal soil stiffness [KLH], Downward vertical soil stiffness [KLS], Sub-soil bearing capacity [RVS], Ultimate top soil reaction [RVT], Ultimate hor. soil reaction [RH], and Upward vertical soil stiffness [KLT] is soil type dependent. The soil types are divided into two groups. The first group consists of gravel, sand and loam. The second group consists of clay and peat. NEN 3650 makes a distinction between sand and clay/peat.

For information on the formulae used see Calculation.)

Soil subtype:

Subtype of main soil type sand: Clean, slightly silty, highly silty

Required for sand / Prescribed name

(The soil subtype is only used in the NEN3650-1:2020 calculation methodology and for the sand soil type. It is used to determine the Effective angle of internal friction. See also Angle of internal friction.)

Colour:

Identity colour of soil type used in Soil Model Wizard graphical representations

Required

(The image representing the soil type has a texture dependent of the soil type and is filled with the identity colour.)

Volume weight of soil with natural humidity

Required

(The volume weight of the soil is used in calculation of the neutral soil load, which in turn is used for determination of the Ultimate top soil reaction [RVT], Sub-soil bearing capacity [RVS] and Neutral or real top soil load [SOILNB].

For the NEN3650-1:2020 calculation methodology it is also used to calculate the adapted Young's modulus at specific location.)

Volume weight (saturated) {γ}:

Volume weight of saturated soil

Required

(For soil below water level (as can be specified as input for the Soil Model Wizard in output table Vertical profile data [PROFILE]) the volume weight of saturated soil is used instead of the (mean) volume weight.

In calculation of the neutral soil load of soil below water level the volume weight of water is distracted from the saturated volume weight of the soil to compensate for the water buoyancy.)

Angle of internal friction {φ}:

Angle of internal friction of soil

Required

(The angle of internal friction is used in calculation of Pipe-soil friction [F] and Ultimate hor. soil reaction [RH]. For soil types classified as sand (gravel, sand and loam) it is used in calculation of Sub-soil bearing capacity [RVS], Downward vertical soil stiffness [KLS] and Horizontal soil stiffness [KLH]. If no angle of pipe-soil friction is supplied the angle of internal friction is used to determine the angle of pipe-soil friction for soil types classified as clay (clay and peat). The angle of internal friction is also used in calculation of Ultimate top soil reaction [RVT] for pipelines laid at large depths (reduced Top soil reaction due to vault behaviour of soil).

For the NEN3650-1:2020 calculation methodology, for soil types defined as sand, the angle of internal friction is adapted to obtain the effective angle of internal friction using the effective Young's modulus at specific location.)

Angle of pipe-soil friction {δ}:

Angle of friction between pipe and soil

Optional

(If not provided the value for sand is defined according NEN 3650, which takes an angle of pipe-soil friction of 20°. For clay and peat the angle is defined as 2/3 * Angle of internal friction.

The angle of pipe-soil friction is used to calculate Pipe-soil friction [F].)

Cohesion of soil when drained

Optional

(If not provided a default value of 0 is used.

Drained cohesion is used in calculation of Pipe-soil friction [F] and in calculation of Ultimate top soil reaction [RVT] of pipelines laid at large depths (reduced Top soil reaction due to vault behaviour of soil).)

Cohesion of undrained soil

Conditional (Required only for clay/peat soil types)

(Undrained cohesion is used in calculation of Ultimate hor. soil reaction [RH] and Sub-soil bearing capacity [RVS] for soil types classified as clay (clay and peat). Both Ultimate hor. soil reaction [RH] and Sub-soil bearing capacity [RVS] will be 0 (zero) for soil types classified as clay (clay and peat) if no undrained cohesion is provided.)

Packing factor of soil type

Optional

(If not provided a default value of 0.3 is used.

NEN 3650 takes a packing factor of 0.3 for reasonably loosely packed soil and 0.8 for well packed soil. For a trench width smaller or equal 3 times the pipeline diameter at pipeline axis level a packing factor of 0.1 is opted. For trench widths smaller then 1.5 times the pipeline diameter a packing factor of 0 is proposed.

The packing factor is used in calculation of the Ultimate top soil reaction [RVT].)

Shrinkage pressure {D0·Kvmin}:

The shrinkage pressure of soil type is defined as the outer diameter of the pipeline multiplied with the minimum subgrade reaction modulus

Required

(The shrinkage pressure is only used in the NEN3650-2020 calculation methodology. It is used in calculation of Neutral top soil load [SOILNB] when using 'use real top soil load for Neutral top soil load calculation' setting (for more information check Soil Model Wizard settings).)

The shrinkage percentage of the soil type, uncompressed

Required

(The shrinkage percentage is used in calculation of Neutral or real top soil load [SOILNB] when using 'use real top soil load for Neutral top soil load calculation' setting (for more information check Soil Model Wizard settings).)

Shrink. perc. compressed {μcompr}:

The shrinkage percentage of the soil type, compressed

Required

(The shrinkage percentage compressed is only used in the NEN3650-1:2020 calculation methodology and when the installation method is trench compressed fill. It is used in calculation of Neutral or real top soil load [SOILNB] when using 'use real top soil load for Neutral top soil load calculation' setting (for more information check Soil Model Wizard settings).)

Shear modulus of soil type

Required

(The shear modulus is used in calculation of Ultimate top soil reaction [RVT] of pipelines laid at large depths (reduced Top soil reaction due to vault behaviour of soil).)

Ultimate friction distance of soil type

Required

(The ultimate friction is used to determine the Displacement at max. soil friction [UF].)

Young's modulus of soil type for an effective vertical grain pressure of 100 kPa

Required

(The Young's modulus is only used in the NEN3650-1:2020 calculation methodology. The Young's modulus is adapted for the effective vertical grain pressure as applicable for the calculation. It is used to determine Downward vertical soil stiffness [KLS] when the installation method is non-trench (Boring, HDD) or when the installation method is trench (trench uncompressed fill, trench compressed fill) and the soil type is classified as sand (gravel, sand or loam). The Young's modulus is also used in calculation of Upward vertical soil stiffness [KLT].

Furthermore it is used to determine the effective angle of internal friction at specific location.)

Description:

Descriptive text for the specific soil type

Optional

Last changed: 7/2/2021