Undercut benching for fill slope

Do you have any other parameters for this related to fill heights? Ideally, you would want this as consistent as possible going from section to section, specific to the # of benches, but you could handle this with your standard EC establishing fill height, then use a combination of null points and components utilizing display rules to turn on/off the different scenarios based on the fill height. It is doable, but will require some planning/forethought/understanding of how existing ground influences the solutions related to the detail. If you have any other design parameters that would influence how this template solves, please share and we can try to come up with a solution for you.

Hi Justin, thanks for the response.  There is no variance in parameters based on fill height.  Whether it's a 10' high embankment for a 30' high embankment, the same parameters exist for the undercut bonding benches (3' below existing ground, min 3' horizontal length of bench, max 4' high vertical length of bench).  And then typically, when the bonding benches gets within 3' of the proposed pavement box then we'll have it tie in at a 1:1 slope to complete it.

I'm thinking I need:

1) a null point that tracks vertical distance from the existing ground, such that when 3' of depth is available, drop a horizontal line

2) Another condition that sets the horizontal length of the bench to be a minimum of 3', OR 3' depth below the existing ground, whichever results in the longer horizontal distance

3) Another condition that sets the vertical length of the bench to be a maximum of 4', OR 3' depth below the existing ground, which results in the shorter vertical distance.

4) Another condition that checks when the undercut bonding benches gets to be within 3' of the bottom of proposed pavement box, and if that's true, then start the 1:1 slope to tie it in. 

The issue is, there could be a large amount of bonding benches, depending on how high the embankment is, and what the existing ground is doing. So I'm not sure if there's a way to automate it in a way where the template can repeat the conditions until condition 4 is met.  

Here's a snippet from a cross-section from a job from a couple years ago (this was done in Inroads, so we just manually drafted in the benching on the cross-section) 

OK - I made this really quick and haven't fully vetted it, but I will dig into this a little more tomorrow when I have more time. The steps below will require the creation of some additional terrain models for target aliasing purposes to make the template work.

• Grading corridor with 2:1 slope and toe object
  1. 0.5% bench of toe object should be the horizontal minimum of the existing hinge and proposed hinge
     1. Null Point in template that can horizontal feature constrain or point control to a linear object that represents the existing (approx.) hinge location. **I am estimating here to account for the 3' min. clear to existing ground.
  2. Target Alias Benching EC to FG surface offset 3’ (Subgrade TM - Need to Create)
     1. Can use alternate surface or graphical filter to pull subgrade features for feature creation à delta TM of -3’ for design from this TM
  3. Target Alias 1:1 tie in with alias of “EG-Tie”
     1. May need to make a new TM solely for this purpose. Use null complex terrain technique with EG and a delta of EG for this.

Here is a snapshot of the test of this concept in the ITL. Again, I did this really quick and haven't tested on a dataset. The diagonal white line represents EG (haven't adjusted NP to extend 0.5% base, but that would increase to the left based on this scenario). Magenta is the max benches from the example in an EC that is benching. Green coming off of the magenta is the 1:1 EC targeting EG.

Again, I will dig into this a little more tomorrow when I have some more time. This may be a wash when I try on a real dataset, but wanted to share some ideas that you could potentially try.

HTH,

Justin

OK - I made this really quick and haven't fully vetted it, but I will dig into this a little more tomorrow when I have more time. The steps below will require the creation of some additional terrain models for target aliasing purposes to make the template work.

• Grading corridor with 2:1 slope and toe object
  1. 0.5% bench of toe object should be the horizontal minimum of the existing hinge and proposed hinge
     1. Null Point in template that can horizontal feature constrain or point control to a linear object that represents the existing (approx.) hinge location. **I am estimating here to account for the 3' min. clear to existing ground.
  2. Target Alias Benching EC to FG surface offset 3’ (Subgrade TM - Need to Create)
     1. Can use alternate surface or graphical filter to pull subgrade features for feature creation à delta TM of -3’ for design from this TM
  3. Target Alias 1:1 tie in with alias of “EG-Tie”
     1. May need to make a new TM solely for this purpose. Use null complex terrain technique with EG and a delta of EG for this.

Here is a snapshot of the test of this concept in the ITL. Again, I did this really quick and haven't tested on a dataset. The diagonal white line represents EG (haven't adjusted NP to extend 0.5% base, but that would increase to the left based on this scenario). Magenta is the max benches from the example in an EC that is benching. Green coming off of the magenta is the 1:1 EC targeting EG.

Again, I will dig into this a little more tomorrow when I have some more time. This may be a wash when I try on a real dataset, but wanted to share some ideas that you could potentially try.

HTH,

Justin

Awesome thanks so much for looking into this and trying out this test concept, I'll try to run with this method on my template and see how it works out. 

After we get this part figured out, the next step will be seeing how the quantities work out.   There's embankment (above the existing ground and below the proposed 2:1 fill slope), excavation (the undercut benching), and more embankment (filling the benches back in with embankment).  

And then there's other conditions where the toe bench area is rock.  But I think getting the quantities to work for that would be relatively easily, just need to have the material component set up for the toe bench to be rock, and that should be pretty straight forward.