Author Topic: Vertical cross section of a Tunnel pipe problem  (Read 6260 times)

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ekoneo

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Vertical cross section of a Tunnel pipe problem
« on: January 27, 2015, 10:12:27 AM »
Hi all,
I prepare a small tunnel corridor model. The radius is 4m.
The tunnel's profile has a %5 vertical profile slope. I finished the model. I draw all sections.
Then I try something. I increased the slope up to %60. I know this impossible condition for a tunnel construction.
But I wonder that what happens on the model.
All corridor sections are consisted vertically. So the tunnel radious goes smaller.
However the tunnel radious becomes smaller, the section drawings shows the radious 4m.
How can I draw the sections that are perpendicular to the profile slope?

mjfarrell

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Re: Vertical cross section of a Tunnel pipe problem
« Reply #1 on: January 27, 2015, 10:19:20 AM »
Hi all,
I prepare a small tunnel corridor model. The radius is 4m.
The tunnel's profile has a %5 vertical profile slope. I finished the model. I draw all sections.
Then I try something. I increased the slope up to %60. I know this impossible condition for a tunnel construction.
But I wonder that what happens on the model.
All corridor sections are consisted vertically. So the tunnel radious goes smaller.
However the tunnel radious becomes smaller, the section drawings shows the radious 4m.
How can I draw the sections that are perpendicular to the profile slope?

I don't think your models shows what you think it does....
Let me test here...is the tunnel bottom flat, than an arched section?
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Michael Farrell
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mjfarrell

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Re: Vertical cross section of a Tunnel pipe problem
« Reply #2 on: January 27, 2015, 10:39:46 AM »
here...
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Michael Farrell
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ekoneo

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Re: Vertical cross section of a Tunnel pipe problem
« Reply #3 on: January 27, 2015, 10:42:11 AM »
I try to sketch it below

mjfarrell

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Re: Vertical cross section of a Tunnel pipe problem
« Reply #4 on: January 27, 2015, 10:43:52 AM »
how or what did you use for your circular assembly?

there are at least two good ways- sub assembly by polyline....or generic links....have fun working out the slopes for that one!
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Michael Farrell
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ekoneo

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Re: Vertical cross section of a Tunnel pipe problem
« Reply #5 on: January 27, 2015, 10:58:13 AM »
I increased your profile slope. I make the section interval distance 5m.  I rebuilt your corridor. Then I upload here.

ekoneo

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Re: Vertical cross section of a Tunnel pipe problem
« Reply #6 on: January 27, 2015, 11:05:01 AM »
I made it with subassembly from a polyline.

mjfarrell

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Re: Vertical cross section of a Tunnel pipe problem
« Reply #7 on: January 27, 2015, 11:05:33 AM »
I increased your profile slope. I make the section interval distance 5m.  I rebuilt your corridor. Then I upload here.

Move my sample line to any station and the cross section is normal....i.e. I don't see any problem with the model
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Michael Farrell
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mjfarrell

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Re: Vertical cross section of a Tunnel pipe problem
« Reply #8 on: January 27, 2015, 11:07:04 AM »
if one uses the DRIVE command it does 'appear' to be wrong...however that is just a perception.
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Michael Farrell
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ekoneo

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Re: Vertical cross section of a Tunnel pipe problem
« Reply #9 on: January 27, 2015, 11:29:04 AM »
The problem is cross sections shows normal. But corridor sections are not perpendicular to the profile line. They are perpendicular to Y axis.
Although radious decrease, the crosssection shows normal. I need the cross section that is perpendicular to the road profile line.

mjfarrell

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Re: Vertical cross section of a Tunnel pipe problem
« Reply #10 on: January 27, 2015, 11:34:58 AM »
sounds like you would be wanting to use EXTRUDE and SLICE to get sections from a solid...not roadway sections..

or provide ample of what you have, and what you think you want...

I'm pretty sure the software is performing as expected...
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Michael Farrell
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ekoneo

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Re: Vertical cross section of a Tunnel pipe problem
« Reply #11 on: January 27, 2015, 12:03:36 PM »
I atached a photo from your corridor. On vertical side tunnel becomes thin. But Tunnel corridor width and height should be constant.

mjfarrell

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Re: Vertical cross section of a Tunnel pipe problem
« Reply #12 on: January 27, 2015, 12:27:38 PM »
oblique/vertical exaggeration  i.e. Don't trust your eyes on this one
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Michael Farrell
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mjfarrell

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Re: Vertical cross section of a Tunnel pipe problem
« Reply #13 on: January 27, 2015, 12:31:41 PM »
from side view................same size....
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Michael Farrell
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ekoneo

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Re: Vertical cross section of a Tunnel pipe problem
« Reply #14 on: January 28, 2015, 02:54:54 AM »
Hi mjfarrell,

I think about your last post during a long time.
Then I had a question myself..
I try to sketch it.
In the sketch,
The train's height is not parallel to your measurement direction. If the slope increase the tunnel height become smaller than the train's height (theorically).

mjfarrell

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Re: Vertical cross section of a Tunnel pipe problem
« Reply #15 on: January 28, 2015, 07:40:23 AM »
I think you are 'over' thinking it....a 4 meter bore is still a 4 meter bore irrespective of the incline the boring machine is working at.

Also consider that no sharp changes in deflection either horizontal or vertical are going to happen.
This both so the boring machine can negotiate the turn AND the train cars.  Otherwise every subway in the world would be plugged up with stuck trains right now.
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Michael Farrell
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mjfarrell

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Re: Vertical cross section of a Tunnel pipe problem
« Reply #16 on: January 28, 2015, 09:55:20 AM »
OK, I now see the issue. Much more clearly...

The cross section is projected perpendicular to the alignments with the controlling alignment being the Horizontal NOT the vertical alignment...and yes this distorts the

tunnel section. 

Good luck on any change to that coming from Autodesk.

Also I don't see any easy fix for this....However As stated earlier, on could resort to standard 3d solids EXTRUDE, or SWEEP command to model the tunnel and other features.

OR...and I have not tried this....Rotate the UCS and model this thing on it's side.....it may take a left and right version.
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Michael Farrell
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ekoneo

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Re: Vertical cross section of a Tunnel pipe problem
« Reply #17 on: January 28, 2015, 10:24:09 AM »
Thanks mjfarrell.
It seems difficult :)
As a result of my internet researches, i read a little tip from autodesk forum.
http://forums.autodesk.com/t5/autocad-civil-3d-general/tunnel-corridor-becomes-shrink-on-very-high-vertical-slope/m-p/5485676#M266618

As BrianHailey said In SAC, there is a way to set the profile slope value to a parameter.
If it is possible to distort the subassemblies depending on that parameter, I can get correct result.
Unfortunatelly it seems complicated for me  :|
« Last Edit: January 28, 2015, 10:29:51 AM by ekoneo »

mjfarrell

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Re: Vertical cross section of a Tunnel pipe problem
« Reply #18 on: January 28, 2015, 10:49:15 AM »
one could do a similar thing by setting a target profile for the top of tunnel to follow...without SAC.
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Michael Farrell
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