Problem description

The PLAXIS 3D embedded beam element is a versatile element that can be used for different purposes, for instance, a pile, rock bolt or as a ground anchor. To model the latter, we can use a combination of an embedded beam for the bonded part/grout body and a node-to-node anchor as the free length.

To do so, we need to make sure that the connection between the embedded beam and the node-to-node anchor is set up correctly such that the node-to-node anchor and the embedded beam are fully connected while that shared node is not connected to the surrounding soil.

For this specific connection, it is possible to set the behaviour of the embedded beam to be "Grout body", ensuring the correct connectivity.

Figure 1. Different types of behaviour for embedded beam

However, when generating the mesh in Mesh mode, this behaviour setting will trigger an application error that will prevent further progression with the project, as shown in Figure 2.

Figure 2. Error that occurs when generating the mesh with the grout body setting

The error does not occur if the behaviour of the embedded beam is set to "Pile" or "Rock bolt".

Workaround

This issue is now solved in PLAXIS 3D 2023.2.1. Please update to this version when encountering this meshing issue in PLAXIS 3D.

For PLAXIS 3D 2023.2.0, setting the behaviour of the embedded beam(s) to "Pile" with a connection set to "Free" will circumvent this issue to occur and reproduce the same behaviour of a grout body. Ensure that your connection point is set at the connection point of the node-to-node anchor.

In general, when an anchor and an embedded beam with the behavior "Grout body" are connected, the anchor will be automatically connected to the embedded beam connection point. By specifying the behaviour of the embedded beam to "Grout body", the connection type is intrinsically set to "Free", meaning free from the surrounding soil volume.
Therefore, assigning the behaviour of the embedded beam to “Pile” with a “Free” connection will be the equivalent of having the behaviour set to “Grout body”.

Figure 3 - Setting the behaviour of the embedded beam to "Pile".