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Distinguished Contributor
taneum
Posts: 136
Registered: ‎01-07-2005
Message 1 of 24 (329 Views)

Tieing Into Existing Berm

329 Views, 23 Replies
12-12-2012 09:23 AM

This is a real doozy my boss wants done.  We have and existing sewer lagoon with 4:1 side slopes.  We are designing a bypass pipe outside of the 4:1 side slope but because of cover issues, we need to add some dirt to the side slope to fill above the pipe.  He wants to continue that 4:1 side slope up until it matches the profile elevation abaove the pipe.  Once that happens, then grade a 12' wide berm with 2% crown each way and then come back down the other side at a 4:1 until it matches existing grade.  We drew a target line at the tope of the existing 4:1 on the existing ground and used that as a start point. 

 

Here is the problem, we are using the "linkwidthandslope" sub-assembly, how do we tell it to go up at a 4:1 until it matches our design profile grade?  Horizontally, that right side of the sub-assembly wil be different in every cross section,but vertically it needs to match the profile.  The left side of the sub-assembly is working okay and tieing in at the top of the existing 4:1 slope.  The right side of the sub-assembly though is tieing in at the design profile grade vertically and at the alignment centerline horizontally.  When this happens, my slopes all differ and they cant, they need to go up at a 4:1 so the existing 4:1 slope continues going up.

 

Does this make sense to anyone?  Its a tough one.

 

Attached are some pictures.

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troma
Posts: 2,519
Registered: ‎05-21-2008
Message 2 of 24 (327 Views)

Re: Tieing Into Existing Berm

12-12-2012 09:30 AM in reply to: taneum

Having some trouble following, I think more pictures might help.

 

Isn't it possible to give a target profile without targeting an alignment?  Use a link at a specified slope (4:1) targeting the design profile.


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Distinguished Contributor
taneum
Posts: 136
Registered: ‎01-07-2005
Message 3 of 24 (325 Views)

Re: Tieing Into Existing Berm

12-12-2012 09:37 AM in reply to: troma

I have targets set up to a feature line in which the left side of the sub-assembly ties into.  This is at the top of the existing berm.  The problem is, why does the right side of the sub-assembly autommatically tie into the profile design grade?  Is the "linkwidthandslope" sub-assembly the wrong one to be using?

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troma
Posts: 2,519
Registered: ‎05-21-2008
Message 4 of 24 (310 Views)

Re: Tieing Into Existing Berm

12-12-2012 10:24 AM in reply to: taneum

It looks to me as if you have a slight crown (2%?) and then the right side is targeting the surface at 4:1. Is that not what's happening?  It looks like it starts at the bottom of that 2% and then targets the surface. What do you want it to do?

 

 

In your first message, here is an intersting line:

"He wants to continue that 4:1 side slope up until it matches the profile elevation abaove the pipe."

So, you want to start at the existing top of 4:1 slope (horizontal and vertical requirement)

You want to end at the profile elevation (vertical requirement)

You want to end above the pipe (horizontal requirement)

 

It sounds like you have horizontal and vertical requirements for the bottom and top of this slope, so how can you also give it a slope requirement (4:1)?  Unless you give the top the freedom to move horizontally so as to be not above the pipe, it can't calculate the slope.


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LisaPohlmeyer
Posts: 513
Registered: ‎01-14-2009
Message 5 of 24 (298 Views)

Re: Tieing Into Existing Berm

12-12-2012 11:09 AM in reply to: taneum

How about a LinkSlopeToElevation link instead?

Lisa Pohlmeyer

C3D 2012 SP4, C3D 2015
Please use "Accept as Solution" if this solved your issue.
Distinguished Contributor
taneum
Posts: 136
Registered: ‎01-07-2005
Message 6 of 24 (282 Views)

Re: Tieing Into Existing Berm

12-12-2012 12:23 PM in reply to: LisaPohlmeyer

Troma laid it out correctly.  Yes, I want to continue that existing 4:1 slope up on the left side until it matches the elevation of my design profile.  With that being said, the horizontal location of where that 4:1 slope will stop varies because my design profile drops at 0.570%.  If you look at the .pdf I attached earlier, you can see that the red dot where it is supposed to stop is actually right of the centerline.  The offset at which it stops though in each cross section will vary since the existing top of the 4:1 slope varies in distance from my alignment centerline.

 

Lisa, good thought but the "linkslopetoelevation" want a constant elevation to project up to.  In my case, the 4:1 slope needs to continue project up until it meets the design profile elevation at that particular cross section.

 

Once that happens, I will then attach "linkwidthandslope" sub-assemblies to creat a 12' wide berm and then tie back into the existing grade.

 

The right side is working fine.

 

If you can picture this correctly, when it works, the new pipe (which is down the center of my alignment) will run somewhere under the 4:1 side slope that is being continued up.  The center of my new berm will float from left to right over the pipe and alignment centerline.

Distinguished Contributor
taneum
Posts: 136
Registered: ‎01-07-2005
Message 7 of 24 (277 Views)

Re: Tieing Into Existing Berm

12-12-2012 12:44 PM in reply to: taneum

How are the targets programmed to work?  Does it assume that if your sub-assembly is on the left side of the baseline that the left point code of the sub-assembly is what gets targeted to your target lines and vice versa, if your sub-assembly is on the right side of the baseline then the right point code of the sub-assembly gets targeted to your target lines?

 

Thats what it is doing in this case, the left side of my "linkwidthandslope" sub-assembly is targeting my target line which is good but the right point code just defaults to the design profile elevation at centerline.  I really want that right point code to keep going up at a 4:1 to the same elevation of the profile.

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troma
Posts: 2,519
Registered: ‎05-21-2008
Message 8 of 24 (259 Views)

Re: Tieing Into Existing Berm

12-12-2012 01:26 PM in reply to: taneum

As I understand it, the whole assembly needs an alignment & profile to start from.  It can then target other alignments & profiles as necessary, or not.  If the one point that is absolutely concrete is the top of the existing berm, you need an alignment and profile running exactly along the top of berm.  (Alignment tracing the top of berm, profile from surface.)  That should be the anchor point of your assembly.  You will need to target the other profile with a 4:1 slope for starters, then put your 2% crown, then matching existing the other side.

 

If you use the pipe alignment as the anchor point it can't work, because it is anchored horizontally to that location.


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Valued Mentor
fcernst
Posts: 1,089
Registered: ‎01-07-2011
Message 9 of 24 (257 Views)

Re: Tieing Into Existing Berm

12-12-2012 01:30 PM in reply to: taneum

You could do it piecewise.

 

You first goal is to find the meandering alignment for the red dot,  located vertically at the desired pipe cover profile elevation, correct?

 

  1. Run a flat and wide, all encompassing reference surface using the desired pipe cover Profile. 
  2. Run an assembly with 4:1 daylight attached along the exisitng toe alignment and profile, that daylights up to your reference surface.
  3. Now you have located your meandering red dot alignment and profile to build the 12' berm off of.

 

 

Fred Ernst, PE
C3D 2015
Ernst Engineering
www.ernstengineering.com
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troma
Posts: 2,519
Registered: ‎05-21-2008
Message 10 of 24 (250 Views)

Re: Tieing Into Existing Berm

12-12-2012 01:36 PM in reply to: fcernst

Fred, it's simpler than that.  It's just a matter of priorities.  You need to build the assembly with the same priorities as you want the berm to have.

 

1. You start from the top of existing berm.

2. Go up at 4:1 until you hit the profile elevation.  (you may have to superimpose the design profile onto the profile view of the 'top of berm' alignment)

3. Go up at 2% whatever distance.

4. Go down at 2% whatever distance.

5. Go down at 4:1 until you hit the existing ground.


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