So, in class last week, I had some folks that work in the mining industry and they needed to create a filling curve. What’s a filling curve you ask? Well, you know what the final grade is going to be but, how much volume material have you placed in this area once it reaches a specific elevation, well, that’s a filling curve.
I was racking my brain on how to do this. An elevation analysis didn’t work on the volume surface because that gave me the depth of fill, not the elevation of fill. With the new Volumes Dashboard Extension available through the subscription website, I came up with a solution. Now, this won’t actually plot a curve for you but it will compute the volumes at any elevation for you.
To start off with, you need two surface, 1) the existing ground and 2) the filled in surface (in this example, I’ll refer to them as EG and Fill Stack). In order for this to work, the existing ground must be trimmed out to the exact limits of the proposed ground so extract the border from the proposed ground and use it as a boundary in the existing ground (I would recommend creating a new surface, pasting the original EG into it and applying the boundary to that rather then modifying the original EG).
Just so you can see what is going on, here is a cross section across the site.
As you can see, the existing ground varies quite a bit so it’s important to take that into consideration. What we need to do now is create a flat surface that represents the elevation that we have filled. Simple, create a rectangle, assign it the elevation you want, and add it to a knew surface (I’ll refer to this one as the Level surface). Now we can see this new surface in our cross section.
The desired volume at this particular station is between three surfaces, the EG, the Fill Stack, and the Level surfaces. The volume we require is shown below but I can’t get that from comparing only two surface, I need to compare all three surfaces.
I can calculate the fill between the Level surface and the Fill Stack surface
And I can calculate the cut between the EG surface and the Level surface
You might have noticed that the required volume we need is the green fill area subtracted from the red cut area, and this is where the magic begins. Launch the Volumes Dashboard (it’s an extension if you are still using 2012 and, if history repeats itself, it’ll probably be incorporated into 2013 or whatever the next release will be) and create the two volumes surfaces that will result in the above cut and fill. The first Volume Surface I’ll create will have a base surface as the Fill Stack surface and the comparison surface of the Level surface (this one will be called Fill to Level) and the second Volume Surface I’ll create will have a base surface as the Level surface and the comparison surface of the EG surface (This one I’ll call Level to EG).
Unfortunately, right now, the numbers you are seeing aren’t correct. The reason for this is because the volumes surfaces are still taking into account the volume above the Level surface, I only want it to take into account the volume below the Level surface.
Well, the volume dashboard allows you to apply different cut and fill factors so, to prevent the volumes above the level surface from being used, simply set the cut or fill factor for that portion to zero.
Now simply move your Level surface up and down (grab the polyline and use the move command). If everything is set to “Rebuild Automatic” you’ll see these number automatically update. Now, there is no way that I’m aware of to take these number and have them automatically create a curve but you can have excel open on your other monitor and simply move the Level surface and type in the volume into Excel, repeat until you are done.
Now, you wouldn’t be keeping your license or job for long if you didn’t do some double checking so, how can you make sure the numbers you are seeing are correct? Well, create a new volume surface that compares the EG and the Fill Stack so you know what the total volume is and then move your Level surface above the highest elevation of your Fill Stack (the numbers should be the same) and then move your Level surface below the lowest elevation of your EG surface (the volume should be zero).
One thing to make sure you do is to uncheck the volume surface you are using as the check so it’s not included in the totals on the left of the dashboard.
Hopefully you’ll start to see the value of using the volumes dashboard and some of the things you can do with it. The more I use it, the more I like it. If you come up with any other great ideas on how to use it, let me know and if they are awesome enough, I just might write a post about it and give you credit for it.
For more information on the Volumes Dashboard Extension, you can read about it HERE.