Thursday, 27 September 2012

River Sections for Civil 3D

The video below is a quick look at some of the functionality of an add-on piece of software we have been developing for Civil 3D. It is used for the processing and drafting of river cross section and long. section data. The software also outputs data to ASCII file format for input into a number of hydrologic modelling software packages. This video demonstrates how the tools can be used to quickly generate and label cross sections for a typical reach.... more videos on the cross section editing tools and creation of the long sections to follow....

Wednesday, 5 September 2012

Volume Calcs. from Sections

I was creating an as built Civil 3D model of a windfarm job and was asked to calculate a number of quantities. One was the volume of rock fill. This seemed straight forward - compare finished road surface against top of rock and you have your answer. The problem was that my finished road surface slopes down from road edge to top of rock and then batters back from there to meet existing ground. A straight comparison between the two would give incorrect volume, see below:
This includes the portion on the outermost batter. The volume we actually require is this:
To get this we need to create a new surface comprising the road edge featurelines and the featureline where the initial embankment intersects the top of rock. First lets look at my assembly… I am using a combination of generic subassembly (linkwidthandslope) and a conditional subassembly to model different conditions in cut/fill.
If you look at creating a surface from the featurelines generated by the corridor you see that all the individual linkwidthandslope subassemblies have a point code P2 and thus only one featureline I can choose (this would effectively give me the same result as choosing top links to create my surface).

You need to create unique point codes for each subassembly and thus unique featurelines to choose from for corridor surface.
Select the subassembly and change the Point Code  in Properties. Road edge here:
Then slope to rock:
Rebuild the corridor and in now corridor surfaces you should see some extra featurelines:
Now on cross sections you should be able to calculate the correct volume for rock fill by comparing this new surface with top of rock: