Geopak/PowerCivil Site Modeler - How do I design a retaining wall?

Ever needed a retaining wall in your site model?  It's easier than you think.  Here's one example.

In the image below, note that the pond and roadway are overlapping:

A quick look at the profile analysis tool shows that the pond is actually undercutting the road.

We want to add a retaining wall between the road and the pond. 

The process we will use for this situation is :

  1. Drape an element on the higher object (Road C) to set the elevation of the top of wall.
  2. Then compute the elevation to the base of the wall at a slope from the bottom of Pond 1.
  3. These are the only two elements that will be in the retaining wall object

NOTE: This does not design a retaining wall of course.  It models the face of the wall as a surface in our design.  The specifics of the actual retaining wall design would require a structural engineering approach.  Our surface design could be used by the structural engineer to set wall elevations however.

I have drawn two lines for the wall. The red line will represent the top of the wall and the green line will represent the bottom. 

Create a new retaining wall object (Modeler > Object > New)

Now, add the top of wall element with the New element tool (Modeler > Element > New/Edit)

 

  • We are using the drape option.
  • Since we have only two elements in this object we can make them both boundaries.
  • Turn off the offset height (It might be reasonable to add a little extra height. For example, if you wanted a barrier rail to prevent falling into pond you could add maybe 2 feet offset)
  • Drape option = Entire element
  • Use reference element association so that future changes to the road will update the wall.
  • Select the red line
  • Click APPLY

 

We will compute the base of the wall at a slope from the Pond bottom.

Switch the New element tool to the Slope/Offset Option

 

  • Feature type will be boundary
  • Slope = 1.0%. This will continue the slope we used on the pond bottom.
  • No offset height
  • Projection option = Entire element
  • Turn on Use Reference Element Association
  • Select the green line to be defined
  • Use the Select Reference button and Pick/Accept the pond bottom shape.
  • Click APPLY

Finally we need to make sure the FIFO List is in the proper order to give the correct result. (Modeler > Model > Edit)

The order of the marked objects is important.  Road C must be after Pond 1 so that the Road slopes will flow into the pond.  Retaining wall 1 must be last in order to cut off the Road slopes which spill into the pond and form a wall.