3D monopile generator

The 3D monopile generator builds a complete model: a rectangular block of layered soil with a hollow or solid pile extruded through it. It creates the geometry, the layers and the groups in one action, so that materials, contact and boundary conditions can be assigned immediately afterwards.

Soil body and layers

Field	Meaning
Total soil height (Hsoil)	Depth of the soil block below the ground surface
Soil width in x (Wx)	Extent of the block in the x-direction
Soil width in y (Wy)	Extent of the block in the y-direction
Model type	half or full
Number of soil layers	How many layers the block is divided into
Layer border depths (zi)	The depth of each boundary between layers

Model type decides whether the whole soil block is built or only half of it. A half model exploits the symmetry of an axially or laterally loaded pile about the x–z plane, halving the size of the mesh. It requires symmetry boundary conditions on the cut face. Use full when the loading or the soil profile is not symmetric.

Layer borders are given as depths, positive downwards from the ground surface, and one border field appears for each boundary — two layers need one border, three need two. With a single layer no border is required and the field says so.

The depths must lie between zero and the total soil height, and in increasing order.

Pile

Field	Meaning
Total pile length (Ltot)	Full length of the pile, including the part above ground
Embedded pile length (Lemb)	Length below the ground surface
Outer diameter (Dout)	Outer diameter of the pile
Inner diameter (Din)	Inner diameter — leave at zero for a solid pile

The difference between Ltot and Lemb is the free length standing above the ground surface, which is where a lateral load or moment is applied on a monopile.

Inner diameter greater than zero produces a hollow pile with a wall thickness of (Dout − Din) / 2, which is how an open-ended tubular monopile is modelled. The soil inside the hollow section is generated as its own body — the soil plug — so it can be given its own material and can move relative to the pile.

Lemb must not exceed Ltot, and Din must be smaller than Dout.

Geometry convention

The two sketches in the middle of the window are drawn from the values entered and update as they change. They are the quickest way to confirm that a model is what was intended before generating it.

Top view shows the footprint before extrusion, with the pile at the origin and the x and y axes marked. In a half model the sketch shows the half block, so the symmetry plane is visible.

Side view shows the vertical convention: the ground surface at z = 0, the layer borders as dashed lines, and Ltot, Lemb, Dout and Din marked against the pile.

Note the sign convention. The z-axis points upward, so soil is at negative z, but the layer border depths are entered as positive numbers measured downward.

Creating the model

Create / replace geometry generates the model. Delete previously generated pile-generator geometry first is ticked by default and clears the previous result, which is what makes it safe to adjust a value and generate again.

Delete generated geometry removes what the generator made without creating anything new.

The message area at the bottom reports progress and any problem encountered.

Warning

Both delete actions remove only geometry the generator created — anything in the numgeo_pilegen_soil and numgeo_pilegen_pile layers. Geometry drawn by hand in other layers is untouched, but material assignments and conditions attached to the deleted geometry are lost with it. Regenerate before assigning, not after.

What is generated

The generator creates two layers, numgeo_pilegen_soil and numgeo_pilegen_pile, and a set of named groups ready for assignment:

Group	Contains
soil	The soil body
pile	The pile
layer_01, layer_02, …	One group per soil layer, for assigning different materials
soil-plug	The soil inside a hollow pile
surf-pile-top	The top face of the pile, where load is applied
surf-pile-base	The base of the pile
surf-pile-shaft-outside	The outer shaft surface, for contact with the soil
surf-pile-shaft-inside	The inner shaft surface, for contact with the soil plug
surf-soil-top	The ground surface
surf-soil-base	The bottom of the soil block
surf-soil-outside	The outer vertical faces of the block
surf-soil-sides-x, surf-soil-sides-y	The individual side faces, for boundary conditions

Note

These groups are a starting point, not a limit. Further groups can be created in the Layers and groups window for anything the model needs — a set of nodes along a drainage boundary, a region of soil to be excavated in a later step, the nodes where a displacement is monitored. The generated groups can also be edited: entities can be added to them or removed from them like any other group.

The layer groups are what make a layered profile straightforward: assign a different material to each in the Assign material branch. The shaft surfaces are the master and slave groups of a contact pair, and in a half model the symmetry conditions go on the appropriate surf-soil-sides group.