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Surface Manipulation

62 REPLIES 62
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Message 1 of 63
tysonbird
2291 Views, 62 Replies

Surface Manipulation

I am curious if it is possible to modify only specific portions of a surface? For example, I have recieved an xml surface representing FG for a project, and want to do an earthwork calculation, could I raise and lower only portions of the project say by using specific boundaries for the asphalt paving, concrete etc. and then implement the raise & lower surface feature for these portions of the FG surface.

 

At this time I have been creating multiple surfaces for each particular feature of the site, then paste the FG surface, add a boudary and lower appropriately. Finally, I have to go through and paste each particular feature and its small surface into one "subgrade surface" to get an accurate representation. This method results in countless small surfaces and alot of leg work for something that seems like it should be simple.

 

I know that the surface defentions (FL's or corridors), should they be provided, would make this easy, but there have been several occasions where these are not being made availble by the project sponsor. 

 

 

62 REPLIES 62
Message 21 of 63
troma
in reply to: Joe-Bouza


@Joe-Bouza wrote:

My diagram shows that anything in the proposed section below FG increase the total cut.

Does it increase the cut, or reduce the fill?  You'll never know if you don't go... and model it!

 

 

 

EG -vs-FG surface analysis:

 

Cut:                                                        100 cubic meters

Fill:                                                         200 cubic meters

Unadjusted net                                100 cubic meters (F)

 

Area depth Adjustments for pavement, topsoil, structures etc.: 300 cubic meters

Is that 300 I'm taking out of the fill number in the tender, or adding to the cut number?  Or a bit of both?

 

Total adjusted earthwork:           200 cubic meters (C)

 

I enjoy the debate

Me too. Smiley Wink

 

but no one has mathematically proved this wrong yet Smiley Wink show me the numbers Smiley Wink

I'm using logic, not specific numbers, but I think my point is clear enough.  Look at the diagram you drew.  If you calculated your "Unadjusted net" and then added the adjustment, how would you know the total cut number and total fill number?




 

 

 

 


Mark Green

Working on Civil 3D in Canada

Message 22 of 63
Joe-Bouza
in reply to: troma

I know its logic that what my diagram is based on.

 

I think we can all agree that we have to cut to the datum but we do not have to fill to FG where a proposed element is, and that it what my diagram shows. I don't see the need to model it. If subtract the green area from the fill or add to the cut I still reduce the fill.

 

not exactly sure what you mean by tenders

EG -vs-FG surface analysis:

 

Cut:                                                        100 cubic meters + 200 cubic meter = 300 cubic meters

Fill:                                                         200 cubic meters

adjusted net                                100 cubic meters (c)

 

If you did a cut and fill from EG -vs- Datum you get my diagram.

Thank you

Joseph D. Bouza, P.E. (one of 'THOSE' People)

HP Z210 Workstation
Intel Xeon CPU E31240 @ 3.30 Hz
12 GB Ram


Note: Its all Resistentialism, so keep calm and carry on

64 Bit Win10 OS
Message 23 of 63
fcernst
in reply to: Joe-Bouza

  1. 'If total earth work is done between FG an EG"

Not true. Earthwork should be done as compared between the proposed design subgrade elevation (FG-Subgrade) and a topsoil stripped (per soil report boring logs) existing ground surface (EG-Stripped).

 

2.  "sidewalks curbs drainage structures will always increas the total cut on a job.'

 

Not true. If the proposed design subgrade elevation for these structures is above the EG-Stripped surface, this area would be in Fill. Since the area is now established to be in Fill relative to FG-Subgrade compared to EG-Stripped, there is no increase in Cut in these areas.

 

Cut occurs when Elev(FG-Subgrade)-Elev(EG-Stripped) < 0

 

 

 

 



Fred Ernst, PE
C3D 2024
Ernst Engineering
www.ernstengineering.com
Message 24 of 63
troma
in reply to: Joe-Bouza


@Joe-Bouza wrote:

I know its logic that what my diagram is based on.

 

I think we can all agree that we have to cut to the datum but we do not have to fill to FG where a proposed element is, and that it what my diagram shows. I don't see the need to model it. If subtract the green area from the fill or add to the cut I still reduce the fill.

You're still missing my point.  Point is: I need to know the Cut and the Fill, not just the Total of them both together.

 

not exactly sure what you mean by tenders

The form of tender is the document supplied by the consultant to the contractor with a list of items in the contract.  Part of that will inculde the amount of cut-to-fill on site, and the amount of imported fill required.  Your method would acurately calculate the amount of fill to be imported or exported, but not the cut-to-fill item.

 

EG -vs-FG surface analysis:

 

Cut:                                                        100 cubic meters + 200 cubic meter = 300 cubic meters

Fill:                                                         200 cubic meters

adjusted net                                100 cubic meters (c)

 

Using these numbers, the unknown quantity is the '+ 200 cubic meter'.  This has been calculated by area x depth, and we don't know if the area is in a cut or fill situation.  Therefore, if it is all in cut, the item for cut-to-fill would be 200 cubic meters (since that's all the fill we need).  But if it is all in a fill area, we could now have zero fill, and the same item in the tender would be zero.  Most likely the reality would be somewhere in the middle, but like I said, you won't know if you don't go.

 

 

 

If you did a cut and fill from EG -vs- Datum you get my diagram.


I think Fred understands me.Smiley Happy


Mark Green

Working on Civil 3D in Canada

Message 25 of 63
Joe-Bouza
in reply to: troma

It is computing the totals. thats all

Thank you

Joseph D. Bouza, P.E. (one of 'THOSE' People)

HP Z210 Workstation
Intel Xeon CPU E31240 @ 3.30 Hz
12 GB Ram


Note: Its all Resistentialism, so keep calm and carry on

64 Bit Win10 OS
Message 26 of 63
fcernst
in reply to: fcernst

I should note that, at a minimum, organic topsoil material should be stripped from the EG surface for earthwork per soil boring logs.

 

I am thinking of a site we recently had where it was clearly stated in the geotech's site soil report that a layer of inorganic fat clay soil, as depicted in the soil boring logs, was suceptible to frost heave, and was not suitable to be used as Fill. 

 

It is imperative to have an understanding of the site soil report.



Fred Ernst, PE
C3D 2024
Ernst Engineering
www.ernstengineering.com
Message 27 of 63
neilyj666
in reply to: fcernst


@fcernst wrote:

I should note that, at a minimum, organic topsoil material should be stripped from the EG surface for earthwork per soil boring logs.

 

I am thinking of a site we recently had where it was clearly stated in the geotech's site soil report that a layer of inorganic fat clay soil, as depicted in the soil boring logs, was suceptible to frost heave, and was not suitable to be used as Fill. 

 

It is imperative to have an understanding of the site soil report.


What sort of material is this - never heard anything described like this before?

neilyj (No connection with Autodesk other than using the products in the real world)
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Message 28 of 63
Neilw_05
in reply to: Joe-Bouza

Joe,

 

Perhaps I misunderstood your original comment or you misunderstood mine. To clarify my comment I'll present a scenario.

 

Consider a 5 acre paved parking lot. The pavement structure is 1 foot thick. It was modeled with gradings so there is no subgrade surface available. The FG varies in cut/fill condition throughout the site. How do we compute the earthwork volume (ignore stripping and other factors for simplicity)? We can't just multiply 5 acres times 1 foot deep and add it to the computed FG-EG surface volume. Nor can we mulitple 5 acres x 1 feet deep and subtract it from the surface volume. We would need to apply different formulas for cut vs. fill to compute the earthwork volume to the subgrade.

 

From your diagram I gather you are taking this in to account, but how do we determine the areas that are in cut or fill? As I mentioned, we could generate ISOPACH contours and use those to determine the cut/fill areas, but it is a labor intensive process when you have to break the areas into pieces according to variations in the depth to subgrade.

 

So I'll wait for your clarification on your solution.

Neil Wilson (a.k.a. neilw)
AEC Collection/C3D 2024, LDT 2004, Power Civil v8i SS1
WIN 10 64 PRO

http://www.sec-landmgt.com
Message 29 of 63
fcernst
in reply to: neilyj666

Liquid Limit >= 50 and High Plasticity

 

Capture.JPG

 

 

 

 



Fred Ernst, PE
C3D 2024
Ernst Engineering
www.ernstengineering.com
Message 30 of 63
Joe-Bouza
in reply to: Neilw_05

Hi Neil

 

If I may answer with another question or two with the same criterior as you outlined

 

1. if the 5 acre parking lot is design 100% in fill  then multiplying 5 acre by 1 foot and subtracting  from the gross fill would give the corrected fill volume, no?

2. like wise If the 5acre parking lot is designed 100% in cut, adding 5 acre-feet to the cut would be the correct volume.

 

There by superposition the same hold true for sites in cut and fill, no? You do not need to know which areas are in cut or fill as the diagram shows anything in fill is actually a reduction in fill needed or negative F and negative F = C.

 

It took me a while to swallow too. Its algebra plain and simple.

 

 

Thank you

Joseph D. Bouza, P.E. (one of 'THOSE' People)

HP Z210 Workstation
Intel Xeon CPU E31240 @ 3.30 Hz
12 GB Ram


Note: Its all Resistentialism, so keep calm and carry on

64 Bit Win10 OS
Message 31 of 63
troma
in reply to: Neilw_05

I'll stand with Joe on this one: the totals will be correct.  Absolutely so.

 

But perhaps the point you're making is the same as mine: the total is useless.  We need to know the Cut and the Fill seperately, not just the total.


Mark Green

Working on Civil 3D in Canada

Message 32 of 63
Joe-Bouza
in reply to: troma

Thanks

 

Although I thought my last example demonstrated you will have total cut anf total fill

Thank you

Joseph D. Bouza, P.E. (one of 'THOSE' People)

HP Z210 Workstation
Intel Xeon CPU E31240 @ 3.30 Hz
12 GB Ram


Note: Its all Resistentialism, so keep calm and carry on

64 Bit Win10 OS
Message 33 of 63
troma
in reply to: Joe-Bouza

Once more, I respectfully disagree.  Smiley Tongue

 

In the event that the whole of a given area is in cut condition, then you are right, you can simply add to that cut volume.

 

But what if the whole area is in fill condition when a comparison is made to the FG?  We can't simply subtract from that Fill volume becasue we don't know if we may be introducing some cut volume for part of the area.

 

In the more likely event that a comparison to FG shows some cut and some fill for a given area, you are more or less in the same boat.  I can multiply area by depth, but how much of that "adjustment" volume is a reduction in fill and how much an increase in cut?  Can I use the same proportions as the original cut/fill? No, that would be making wild assumptions about the original ground surface.

 

Joe, you won't know if you no go!


Mark Green

Working on Civil 3D in Canada

Message 34 of 63
Neilw_05
in reply to: Joe-Bouza

Ok, I don't know how we got onto a track that only the net volume matters. In my experience earthwork estimates for cut and fill are always required. Too, there are usually different shrinkage factors between them.

 

So in the scenario where only the net volume is needed then yes we can ignore subgrade cut vs. fill.

Neil Wilson (a.k.a. neilw)
AEC Collection/C3D 2024, LDT 2004, Power Civil v8i SS1
WIN 10 64 PRO

http://www.sec-landmgt.com
Message 35 of 63
Neilw_05
in reply to: neilyj666

I just reviewed Eric's blog post and it is an elegant solution. Very clever.

Neil Wilson (a.k.a. neilw)
AEC Collection/C3D 2024, LDT 2004, Power Civil v8i SS1
WIN 10 64 PRO

http://www.sec-landmgt.com
Message 36 of 63
Joe-Bouza
in reply to: troma

It doesn't matter if it is in cut or fill. a proposed section will always reduce the amount of fiil or increase the amount of cut. If the fill is being reduced (this is all based on the gross numbers of EG-vs-FG) its the same as increasing the cut algebriacly. The bounded volume between EG and FG is fixed. And the proposed section segments are in that controlled volume of EG-vs-FG. clearly the segments in fill region take up fill space and correspondingly the ones in cut do as well. Simple algebra tells us what they a amount to.

 

When you model the subgrade what does it do? It subtracts the fill segments and adds the cut segments. go back to my sketch - its right there

 

What does if I know go mean?

 

 

Thank you

Joseph D. Bouza, P.E. (one of 'THOSE' People)

HP Z210 Workstation
Intel Xeon CPU E31240 @ 3.30 Hz
12 GB Ram


Note: Its all Resistentialism, so keep calm and carry on

64 Bit Win10 OS
Message 37 of 63
Neilw_05
in reply to: Joe-Bouza

Let's consider another scenario,

 

60% of FG surface is in cut, 40% is in fill. After applying the depth to subgrade we find that now 80% is in cut and 20% is in fill. So if we apply area times depth and ignore subgrade cut/fill we have a 40% to 60% cut fill ratio. If we account for subgrade cut & fill we have a 20% to 80% ratio, a considerable difference if shrinkage or different costs for cut/fill are involved.

 

Where am I going wrong here?

 

 

Neil Wilson (a.k.a. neilw)
AEC Collection/C3D 2024, LDT 2004, Power Civil v8i SS1
WIN 10 64 PRO

http://www.sec-landmgt.com
Message 38 of 63
troma
in reply to: Joe-Bouza

I don't usually like to use LOL or similar notations just to spice up my writing, but this is one of those moments when I am literally laughing out loud!  We just can't seem to get on the same wavelength, can we?

 

Yes, the algebra adds up, it is all mathematically correct.  Everything you assert in this last post is true, and I already agreed with you.  But the point is, we need to know the CUT and the FILL, not just the total.  I thought you'd got that, but then you said that in your example you could do it, so I then went on to show that you can't unless the whole area is in CUT.

 

"What does if I know go mean?"

More lol!  Smiley Very Happy

 

Look back over my comments in the thread.  It started as a quote from a song

"...So what's wrong with taking the back streets?

You'll never know if you don't go.

You'll never shine if you don't glow!"

 

Then I abbreviated and changed it a little each time I made the point.


Mark Green

Working on Civil 3D in Canada

Message 39 of 63
Joe-Bouza
in reply to: troma

I'm glad we are very good natured about this and I beg your pardon if I frustrated you  if I missed a point you made. How did you show the Total cut and fill will not be known?

Thank you

Joseph D. Bouza, P.E. (one of 'THOSE' People)

HP Z210 Workstation
Intel Xeon CPU E31240 @ 3.30 Hz
12 GB Ram


Note: Its all Resistentialism, so keep calm and carry on

64 Bit Win10 OS
Message 40 of 63
troma
in reply to: Joe-Bouza


@Joe-Bouza wrote:

I'm glad we are very good natured about this and I beg your pardon if I frustrated you  if I missed a point you made.

Never frustrated, more amused.  Argue the point, not the person. Smiley Happy

 

 

How did you show the Total cut and fill will not be known?

 

That was in my last post, message 33 on the thread by my count.

 

I wonder if we're having terminology problems rather than logic problems.  I need to know the total CUT and the total FILL for each area of a site.  Your method will not do that.  Your method will accurately give me the TOTAL CUT&FILL for each area.


 


Mark Green

Working on Civil 3D in Canada

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