Swept meshing in PLAXIS 3D

General

With the release of PLAXIS 3D CONNECT Edition V20 Update 2, the meshing procedure is enhanced with the new Swept meshing feature.

This feature allows for swept meshes to be generated for particular geometries with volumes, as detailed below.

Figure 1 – Mesh options window with Swept meshing option activated

Swept meshing principles and advantages

The feature Swept meshing refers to the method in which a face of a volume (termed as source face) is meshed and then “swept” along the main volume following its trajectory (termed as sweeping direction), thus creating a volume mesh.

The cross-section of the volume considered should remain constant along the trajectory of the volume, which will allow for the source face to be swept along the sweeping direction.

Figure 2 - Volume to be swept, source face and sweeping direction

Using the Swept meshing feature, when applicable, offers the advantages of:

• Faster mesh generation
• More control over mesh density
• Considerable reduction of the size of the mesh compared to default unstructured meshing process

When the checkbox Swept meshing is activated in the Mesh options window (see Figure 1), PLAXIS 3D will perform an automatic swept mesh detection.

The automatic selection of volumes has 2 steps:

1. Determining which volumes are suitable for sweeping; and
2. Selecting the compatible set of volumes, considering the possible sweep directions, which will actually be meshed with a structured swept mesh.

Note that it is always important to inspect the generated mesh in PLAXIS Output program to ensure that the generated mesh fits the requirements of the calculation.

Requirements for Swept meshing

PLAXIS 3D automatically detects which volumes included in the geometry can be considered as sweepable.

A volume is considered sweepable if:

• It contains at least two surfaces with an identical cross-section which are flat and parallel to each other while being connected only by straight edges.
• It does not contain any NURBS surfaces.
• There are no extra geometric features or any local mesh refinement variations over the sweeping direction that “break” the symmetry of the swept mesh.

Figure 3a - Geometry to be evaluated

Figure 3b - Geometry considered to be swept

Examples

Below you can find some examples comparing the generated mesh with and without activating the Swept meshing feature.

Figure 3c - Generated mesh of pile-raft foundation and intersecting tunnels

Figure 4 - Generated mesh of dual tunnels 

Figure 5 - Generated mesh of NATM tunnel