The next step in is to create a dam shell on the gridded topography and calculate the fill volume. Muk3D has a number of tools for creating dam shells, depending on what data is available. If you already have centrelines (imported from CAD for example) then a dam shell can be created using that alignment. Otherwise it’s easy to draw an alignment to use for the dam.
In this example we’ll draw the dam alignment ourselves, using the following command Structures >> Dams >> Draw a dam.
This command lets you define the dam geometry and draw an alignment, then the resulting shell will be created.
The following data should be used for the dam design:
Several commands in Muk3D will refer to the left and right slope. Left and right relate to the side of the alignment line being used, as it was drawn. These commands do not refer to upstream and downstream as these are terms that can only be applied once the final structure is considered against the surrounding topography.
Hit OK and you’ll be prompted to draw a dam alignment, which in this case will be the crest centreline. When you draw the dam alignment line, a transparent red plane ('Elevation guide') will be shown at the target crest elevation. This helps the user to ensure that the dam alignment centreline ties in with the abutments. An example is shown below.
To ensure complete closure of the dam at the containment elevation, it’s a good idea to start the alignment at a location that is below ground (i.e., outside the red plane), and finish it below ground. Any parts of the dam below ground will be ignored when performing volume calculations.
Once you’ve drawn the centreline, press the Space bar to finish drawing. The dam shell will then be drawn automatically (example below), and the centreline and dam shell will be added to the Scene Manager as new layers.
In the Scene Manager, you’ll notice that some layers are red, bold, and italic. These are layers that have not yet been saved, or have been modified since they were loaded. Muk3D does not automatically save layers, so it’s up to you to save any files you wish to keep.
The first thing to check is that the specified dam slopes are on the intended sides of the dam. If they are the wrong way around, unload the dam shell, rerun the command and either draw the line in the opposite direction, or reverse the left-right slopes in the dialog.
It’s also imperative to check that the dam shell fully intersects the base grid (see image below - shell doesn't penetrate the topography). If it doesn’t, whilst the volume calculations will still work, they won’t be accurate because the dam footprint won’t be properly represented.
Once you’re happy with the dam shell, you can then calculate fill volumes.