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Firstly, what is a Civil 3D Volume Surfaces (Cut and Fill)? Well, let's find out in this online training course. Certainly, this step by step tutorial is a part of the Civil 3D essentials book and how-to manuals.
So far, we have learned how to create a TIN Surface or a “regular" surface. But, there's a second type of surface, a Volume Surface. You guessed it, the main purpose of this type of surface is for estimating volumes or earthworks quantities. Volumes are the amount of material, Cut and Fill, that you will need to transform a surface from an initial to a final state. For example, removing topsoil, altering a site from Existing Ground to Final Ground.
Let's see that in practice by estimating the total volume of topsoil that needs to be removed from the site.
- From the Home tab, launch the Create Surface command.
- In the Create Surface window, for Type, choose TIN Volume Surface, call the surface Topsoil Volume and assign a _No Display Style. A No-Display style is basically a style that we assign to entities we don't need to show in Civil 3D. In AutoCAD, we typically turn off or freeze the layer of entities we don't need to show. In Civil 3D, we do the same thing by assigning the No Display style to specific objects, without needing to manipulate layers back and forth. Since we only need the Volume Surface to estimate earthworks information, there is no need to display it. Sometimes, we are required to create a Cut and Fill areas map. In those cases, we need to assign an elevation style to show the needed information. In this current situation, we don't need to. So, we are using a No Display style.
- Next, define the base surface, the existing ground, by clicking on the three dots to the right
- After that, define the comparison surface, the Stripped surface, by clicking on the three dots on the same line.
- For Cut and Fill Factor, let's use 1.10. These factors control, depending on the soil type, how much the material swells after removal, or how much it is compacted when put in place. This means that for every cubic meter or feet of cut material we will need to haul 1.1 cubic meter or feet. Obviously, it would be the inverse for the fill material. To fill every cubic unit in place, we will need to haul in 1.1 cubic unit. A basic rule of thumb for this is that you are always transporting more volume than what's in the ground. Either when you remove or when you are putting in place.
- Now, click on OK to close the window.
- Nothing shows up in the Drawing Area because we have assigned a No Display style to the volume surface.
- However, the Topsoil Volume surface still appears in the prospector. It has a different symbol than the other surfaces because it represents a Volume surface, while the others are “regular" TIN Surfaces. TIN stands for Triangulated Irregular Network. It is the most common method of interpolating elevations when we are creating a surface.
- The last step consists of checking the volumes. Thisis done from the surface's statistics. In the Prospector, select the surface, right-click and go to Surface Properties.
- Then, on the Statistics tab, expand the Volume tree. Notice the adjusted and unadjusted Cut Volumes. As expected, the adjusted volume is 10% more. And of course, the volume of Fill is zero because we are estimating a topsoil volume, which consists only of cut material.
In summary, this is a quick method for estimating volumes, especially when we have two surfaces we want to compare.