Here is a challenge I'm needing to solve.
I need to rough in a drainage pipe network that connects several structures around a site. The pipe inverts need to be 6.5' below the finished floor of each unit and must maintain a minimum 2% slope. The network needs an outfall at some undetermined point on the site. The pipes must follow some existing roads, so they are not interconnected directly to each structure.
How can I go about determining the potential outfall locations?
Mark Green
Working on Civil 3D in Canada
Thanks for replying. Starting at the lowest unit seems to make sense but the furthest unit is also critical if there is not enough drop at 2% for it to daylight.
After spending some time on this I don't see any other way than trial an error.
Mark Green
Working on Civil 3D in Canada
If Autodesk would ever fix their forums, I'd be able to embed screencasts directly in this reply. Instead, here's a link to a screencast illustrating the steps below.
1. Use a feature line to represent the pipe invert or bottom of pipe path/route.
2. Use the Object Viewer to see if the feature line and TIN EG surface intersect at any point. If yes, proceed to step 3. If no, adjust pipe parameters (slope, length, path/route) until they do.
3. Identify the approximate crossing point.
4. Turn on Triangles in the TIN Surface Style.
5. Use 3DFACE to create a plane that will intersect with your line. If you're not sure exactly which triangle to use, you can repeat the 3DFACE command with the surrounding triangles.
6. Select your newly create 3D Faces, and use CONVTOSURFACE to convert them to surfaces.
7. Explode the feature line into a 3D polyline (necessary for the following step).
8. Extrude (EXTRUDE) your 3D polyline to some small distance (e.g. 0.1; direction doesn't matter; command doesn't work with feature lines).
9. Use SURFTRIM to trim the newly extruded solid.
*You may have to use this command twice as sometimes a small tail is left after the trim. You can check by running inquiry to check if the grip elevation and surface elevation match or by viewing the trimmed solid and surface in the object viewer.
10. Drag the endpoint grip of your 3D polyline to coincide with the newly trimmed end of the extruded surface.
11. Done.
It would be nice if there was a snap for the intersection of a line and a surface, or the ability to use surfaces to trim lines, but this isn't too bad. I use it to find where pipes penetrate the sidewalls of earthen basins.
Here's another way to accomplish this. Requires an alignment, but is more dynamic.
Recently, I've been using the following procedure:
1. "SWEEP" a circle along the pipe path.
*Feature lines can't be used for "SWEEP" path. Object used for used sweep path is deleted, so make sure to make a copy if you want to retain the 3D polyline.
2. Turn on Triangles in the TIN Surface Style.
3. Identify the approximate crossing/intersection point.
4. Use 3DFACE to create a plane from the TIN triangle that will intersect with your line. If you're not sure exactly which triangle to use, you can repeat the 3DFACE command with the surrounding triangles.
5. "SLICE" the resulting 3D solid. Use the 3points option in the command to define the slicing plane using the corners of the TIN triangle previously identified.
6. Drag your pipe line endpoint grip to the sliced solid.
A simpler approach would be to use a grading to surface to find the point where a featureline transitions from cut to fill. Or set an arc feature line at the depth of the lowest pipe and apply a grading to surface at min pipe slope (I.e. 2%) to find the catch point=top of pipe daylight.