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Cut/Fill Calculation

I am trying to work out the cut/fill calculations for a site and having a problem with the result. I have created my site model successfully using existing stake objects, and have proposed site modifier stake objects. Everything seems to be working right because I can switch the site model from proposed to existing, and it shows exactly the change I need it to (it also shows correct in 3d). The area is approximately 50' x 50' and I have raised a central elevation point by more than 2' above the existing.

Why am I getting a cut/fill calculation that is WAY to small? I keep getting results like:

Cut Volume: 0.0044 cu m

Fill Volume: 0.0073 cu m

Net C&F Volume: .0029 cu m

These calculations are clearly incorrect and I can't seem to figure out why it is doing this. I have tried doing other tests and get similar results. Am I maybe forgetting a part of the process in creating my site model?

I am working with Vectorworks Landmark 2010.

Thanks in advance for your help!

Drew

Tags: Calculation, Cut, Fill, Model, Site

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Permalink Reply by Mitch Brooks on February 8, 2012 at 4:19pm

Drew,

First you are mixing units. You are talking about raising one (?) central point by 2' over a 50' x50' (2500 sf) area, no? Perhaps a C&F volume of .0029 cu m is about right. 0029 cu m is the same as 0.1 cu ft which doesn't sound that wrong given your other parameters.

Why don't you make sure that your units are consistent, i.e. all imperial or all metric and give it another look? Or post your file so others can see what is going on.

PS. I am not an expert in Landmark. Others' results may vary

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Permalink Reply by Drew Otway on February 9, 2012 at 9:00am

Thanks, Mitch. I understand I am mixing units, as I did not list the imperial calculations for cut/fill. I did however look at it in all units to see what it said, and it was wrong all around. 0.1 cu feet is an extremely small amount of fill, a few handfuls of soil maybe.

I am still confused by the results. I mentioned the dimensions of the area so that you can tell, if you change a central elevation point and slope the surrounding land up to that point, the fill volume should be much larger.

I am attaching a file with a trial site model I created to test the cut/fill. If you compare the 3d site model's existing versus the proposed, it is clear the cut/fill is wrong.

Thanks for replying to my post!

Attachments:

Sample.vwx, 1.6 MB

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Permalink Reply by Michael G. Terry on February 8, 2012 at 11:55pm

Once you resolve this calculation problem, if this cut/fill is actually executed in the field, note that excavated soils tend to increase in volume as they are broken up -- sand the least, rock the most, and clay in-between. This becomes an issue, particularly, if a significant amount of cut is exported or a significant amount of fill is imported in an *uncompacted* state using fixed-volume containers. If you haven't had to learn this the hard way, then congratulations!

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Permalink Reply by Drew Otway on February 9, 2012 at 9:01am

Thanks a lot Michael, I will note this.

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Permalink Reply by Drew Otway on February 14, 2012 at 12:54pm

Is anyone else able to help me out with this? I still have not been able to figure this out.

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Permalink Reply by Michael G. Terry on February 16, 2012 at 8:09am

Any chance that the scale was accidentally left in the default setting of 1:1?

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Permalink Reply by Drew Otway on February 16, 2012 at 9:25am

Thanks, Michael, but the design layer scale doesn't seem to make a difference in the cut/fill calculation. The scale is not on the default 1:1, but even when I change to that it doesn't affect the calculation.