## AutoCAD Civil 3D General Discussion

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Message 21 of 63 (240 Views)

# Re: Surface Manipulation

02-14-2013 06:38 AM 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.

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

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?

Credit where credit is due! Give kudos or accept as solution whenever you can.

*Expert Elite*
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Message 22 of 63 (235 Views)

# Re: Surface Manipulation

02-14-2013 07:08 AM 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) Civil 3D 2012 & 2013
HP Z210 Workstation
Intel Xeon CPU E31240 @ 3.30 Hz
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Note: Its all Resistentialism, so keep calm and carry on

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Message 23 of 63 (231 Views)

# Re: Surface Manipulation

02-14-2013 07:12 AM 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 2015
Ernst Engineering
www.ernstengineering.com
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Message 24 of 63 (224 Views)

# Re: Surface Manipulation

02-14-2013 07:33 AM 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.

Credit where credit is due! Give kudos or accept as solution whenever you can.

*Expert Elite*
Posts: 4,951
Registered: ‎12-15-2008
Message 25 of 63 (218 Views)

# Re: Surface Manipulation

02-14-2013 07:36 AM in reply to: troma

It is computing the totals. thats all

Thank you

Joseph D. Bouza, P.E. (one of 'THOSE' People) Civil 3D 2012 & 2013
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 Win7 OS
Valued Mentor
Posts: 1,104
Registered: ‎01-07-2011
Message 26 of 63 (208 Views)

# Re: Surface Manipulation

02-14-2013 08:40 AM 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 2015
Ernst Engineering
www.ernstengineering.com
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Message 27 of 63 (203 Views)

# Re: Surface Manipulation

02-14-2013 08:50 AM 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 (199 Views)

# Re: Surface Manipulation

02-14-2013 09:05 AM 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.

Neil Wilson (a.k.a. neilw)
Infrastructure Suite/C3D 2013, LDT 2004, Power Civil v8i SS1
WIN 7 64 PRO
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http://www.sec-landmgt.com
Valued Mentor
Posts: 1,104
Registered: ‎01-07-2011
Message 29 of 63 (195 Views)

# Re: Surface Manipulation

02-14-2013 09:23 AM in reply to: neilyj

Liquid Limit >= 50 and High Plasticity

Fred Ernst, PE
C3D 2015
Ernst Engineering
www.ernstengineering.com
*Expert Elite*
Posts: 4,951
Registered: ‎12-15-2008
Message 30 of 63 (191 Views)

# Re: Surface Manipulation

02-14-2013 09:37 AM in reply to: Neilw

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) Civil 3D 2012 & 2013
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 Win7 OS
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