How to look inside the soil of a 3D model to understand the behaviour
When running a PLAXIS 3D model, the most interesting behaviour and results are usually all inside the 3D soil model. For presentation purposes, we can hide a part of the geometry to present the PLAXIS 3D calculation results. We can then have a look to see how soils and structures inside a 3D model behave, such as displacements beneath an excavated surface and behind the walls of an excavation. We can use different techniques to do this:
An iso-area (or isosurface) is a three-dimensional variation of an isoline. It is a surface that represents points of a constant value (e.g. displacements, strains, stresses, pore pressure, groundwater head) within the volume of the 3D model space. With the iso-areas visualization in PLAXIS 3D Output, the results domain is subdivided in a number of intervals, and for each interval limit, such an iso-area (or isosurface) is shown.This option can give us quick insight into the model behaviour, however, it may not always give insight when using it as a static image, see Figure 1.
Figure 1. Iso-areas for deformations in Tutorial Lesson 2
When using partial geometry options, we can
What all these methods have in common, is that the showing and hiding soil is based on the Finite Elements. This may result in a non-smooth plot due to the unstructured mesh using tetrahedral elements as used in PLAXIS 3D. This can give the following plot when applying it to PLAXIS 3D’s Tutorial Lesson 2, see Figure 2.
Figure 2. Hiding part of the model with partial geometry with a non-smooth cut-surface
Fortunately, there is a way to easily improve the visualization of this. We can do this by introducing helper surfaces at the location where we want to hide the elements.
Example: we want to hide a quarter (or corner) of the 3D model so we can see inside the soil while giving it a clear and smooth visualization. Here we will be using PLAXIS 3D’s Tutorial Lesson 2 again.We can create this using the following steps:
Below you can see the final Output plot view in Figure 3 and Figure 4
Figure 3. Partial geometry using helper surfaces – Deformed mesh
Figure 4. Partial geometry using helper surfaces – Total deformations
See also the attached animation to see the steps to create such a nice visualization: