Tunnel corridor becomes shrink on very high vertical slope .

[ekoneo]

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?

[BrianHailey]

If your slope is small enough and if you don't absolutely need the model precision down to a micron, I would say don't worry about it. The tunnel will be built the way it needs to be.

However, if you do need that precision or the slope is steep enough to cause this to be significant, you would need to create the subassembly via subassembly composer (SAC). In SAC, you can use the profile slope in the calculations of the subassembly so the height of the subassembly (true vertical length) can increase as the slope increases.

Kati Mercier did a class at AU showing how to change the slope of a daylight to maintain a maximum 4:1 slope regardless of the road slope. You would use a similar concept here.

[KMercier_C3D]

You can almost do this in Subassembly Composer. The only real drawback is that what you are wanting to create is an ellipse and there is no specific elipse geometry available but you can fake it with curves based on the major axis and minor axis. 

INPUT PARAMETERS:

• TunnelRadius (Double) = 4
• LayoutProfileSlope (Grade) = 60% [Note that the actual subassembly will calculate based on the profile grade this is just so that you can test to see that the height is changing for various grades]

FLOWCHART:

• Define Variable: ProfileSlope (Double) = if(SA.islayout=true,ctype(LayoutProfileSlope,double),ctype(baseline.grade, double))
• Define Variable: VerticalHeight (Double) = tunnelradius*math.sqrt(1+ProfileSlope^2)
• P1 from origin (x=0, y=0)
• P2 from origin (x=0, y=VerticalHeight)
• P3 from origin (x=0.5*TunnelRadius, y=0.5*P2.Y)
• P4 from origin (x=-0.5*TunnelRadius, y=0.5*P2.Y)
• L1 (Curve) = Arc three points = P4, P2, P3
• L2 (Curve) = Arc three points = P4, P1, P3 

Don't forget to add point and line codes as applicable. 

[KMercier_C3D]

On second thought the 3 point curves aren't going to behave very well for this use but my post above should at least get you the right axis points and then you can set up some intermediate points/links to calculate your own tesselation. 

[ekoneo]

Thanks KMercier,

I need all what you tell above. I will try it. I hope I can achieve.

Thanks so much..