Volume above and below rockheaf

[neilyj666]

I've got an existing and a proposed surface as well as a conjectured rockhead and I need to calculate the volume above and below rockhead. Am I correct in thinking that I need to use sample lines and QTO for this?

[sboon]

Terminology issue - what is a rockhead?

Perhaps a typical section sketch?

Steve
Please use the Accept as Solution or Kudo buttons when appropriate

[neilyj666]

Rockhead is the subsurface rock horizon inferred from boreholes and trial pits - all material above is glacial till (and only partially suitable for reuse) and all the material below can be used as good quality rockfill

[sboon · Accepted solution]

This criteria set goes back to the old software, before subcriteria was an option.  It works but you may be able to create a better set.

Keep in mind that the criteria uses AND logic - Rock Cut for example includes the area which is

• Below ROCK surface
• AND Above DATUM surface
• AND Below STRPPED surface.

We also use the cut and fill factors for masshaul balancing.  We assume that Earth Cut will compact to 90% of its original volume when it's placed in Embankment.  We also assume that Rock will end up with 25% more volume after placement and compaction.

Steve
Please use the Accept as Solution or Kudo buttons when appropriate

[tcorey]

This blog entry might help:

http://timsc3dblog.blogspot.com/2014/01/workflow-for-calculating-multi-material.html

Tim

[fcernst]

..We also use the cut and fill factors for masshaul balancing.  We assume that Earth Cut will compact to 90% of its original volume when it's placed in Embankment.  We also assume that Rock will end up with 25% more volume after placement and compaction...

The Cut/Fill factors are used simply to estimate the required haul volumes in the trucks, and they are usually both greater than 1.

Cut:

If a person cuts 1 cy out of the ground at its insitu density, and dumps it in the back of the truck and find that it "fluffs" up to 1.2 cy in the back of the truck, then Cut Factor = 1.2

Fill:

If you try to fill and compact a 1 cy hole in the ground from the material in the truck, and you find it takes 1.3 cy to fill and compact that hole, the Fill Factor = 1.3. The person needs to account for now that they are going to have to haul 1.3 cy for every 1 cy hole they need to fill.

By using 0.9 for Cut, a person is saying the 1 cubic yard they just cut out of the ground, shrinks to 0.9 cubic yards in the back of the truck.

[fcernst]

This blog entry might help:

You don't have to go through all of this workaround.... The Civil 3D subcriteria alogrithms vertically constrain the surface areas of interest automaticaly for you.

[sboon]

As a designer I am not particularly interested in the volume of material while it's in motion.  What is important to me is the volume required to build the Embankment fill at each section, and the net volume of cut materials available to do so.

If the sections are constructed using only one cut and one fill material then individual shrink and swell factors can be used for each.  Unfortunately this is not possible when multiple sources of cut are being blended into a single fill because it is not possible to predict the ratio of materials available for use at each section.  Additional complications come into play when borrow or waste sites are used, since the factors are not applied to them.

The solution to these issues is to convert the shrink and swell factors into a single blended value and apply it to only the cut side of the equation.

Steve
Please use the Accept as Solution or Kudo buttons when appropriate

[neilyj666]

Thanks for the replies - got the answer I needed.

I just leave the Cut/Fill factors as 1 and work to net quantities - the estimating team can apply their own factors to determine how many trucks will be needed to haul the material....:)

[sboon]

Most people do that, but if you're working in a situation where quantities are important then your design will likely be out of balance, and not as efficient as it could be.

Steve
Please use the Accept as Solution or Kudo buttons when appropriate

[fcernst]

..We also use the cut and fill factors for masshaul balancing..

I thought we were talking about hauling?

...As a designer I am not particularly interested in the volume of material while it's in motion...

Ok...?

..What is important to me is the volume required to build the Embankment fill at each section, and the net volume of cut materials available to do so...

Ok, let's talk Earthwork balancing now then.

...The solution to these issues is to convert the shrink and swell factors into a single blended value and apply it to only the cut side of the equation.

This is not correct, nor how the software was designed to be used. The Refill Factor should be used if a certain percentage of the Cut material is unsuitable to be used for Fill.

1. In your case you would use a Refill Factor of 0.9 for the earth material, and use at least 1.0 for a Cut Factor.

2. Your Rock cut factor looks reasonable at 1.25...i.e. the rock material will "fluff" up 25% with voids, when cut out.

3. You will want to double check your Embankment fill factor. By using a factor of 1.0, you are saying for every cy of fill needed, only 1 cy of whatever they are bringing you is all that is needed. I'm not sure that's the case.

By using the Refill Factor, you can both provide correct haul numbers,  and strive to design an efficient balanced site.

Refill Factor of 0.5 in use:

[fcernst]

...I just leave the Cut/Fill factors as 1 and work to net quantities - the estimating team can apply their own factors to determine how many trucks will be needed to haul the material....

Using a Fill factor of 1.0 is tough on everything...

It's tough on the designer's reputation: 1) The designer thinks they have a balanced site using a Fill factor of 1.0, when in reality they do not. 2) When the designer thinks their site is designed to be a certain purposeful amount out of balance due to constraints, it will be even more out of balance than they thought.

 It's tough on the Owner: Money down the drain.

It's tough on the environment: Larger carbon footprint required to bring, before what was unecessary, but now necessary, Fill to make up the site design deficit.

[sboon]

...As a designer I am not particularly interested in the volume of material while it's in motion...

Ok...?

The volume in the truck, excavator bucket or in front of the dozer blade is difficult to predict, and extremely hard to measure accurately during construction.  This is why we do not use it as a pay quantity, and why we do not worry about it in a typical masshaul calculation.

This is not correct, nor how the software was designed to be used. The Refill Factor should be used if a certain percentage of the Cut material is unsuitable to be used for Fill.

First of all the Refill factor can only be used when the material type is set to Cut and Refill.  The software will not accept any value in the Refill Factor field when any other material type is in use, and it will not accept a value >1 at all.

To clarify further - a Cut and Refill material assumes that soil is removed from an area and then replaced in the same location.  The end areas and volumes calculated for a Cut and Refill area will be added to both the Cut and Fill cumulative volumes.

I've built a sample drawing to allow people to experiment with changing material types and cut/fill factors.  The Earth surface is at elevation 10' and the Rock surface is at 5' through all of the sections.  The corridor uses a single profile slope and a simple section so that all of the material shapes are simple rectangles.  OM Cut is yellow, Rock Cut is red and Embankment fill is green.

This section shows a situation with OM cut only, using a Cut quantity type.  The cut area and volume display as expected.

The second screenshot shows the same section with the quantity type switched to Cut and Refill, and the Refill factor = 1 Notice the change in the Fill quantites in a section that should have no fill.

1. In your case you would use a Refill Factor of 0.9 for the earth material, and use at least 1.0 for a Cut Factor.

2. Your Rock cut factor looks reasonable at 1.25...i.e. the rock material will "fluff" up 25% with voids, when cut out.

3. You will want to double check your Embankment fill factor. By using a factor of 1.0, you are saying for every cy of fill needed, only 1 cy of whatever they are bringing you is all that is needed. I'm not sure that's the case.

For this discussion let's assume that earth will swell by 33% when it comes out of the cut, and that same earth will compact by a little less than 48% when it's placed in an embankment.

100 cf (bank) * 1.33 --> 133 cf (truck) / 1.477 --> 90 cf (fill slope)

For Rock let's assume that after blasting and ripping it will also swell by 33%, but it will only compact by 6% when it's placed in embankment.

100 cf (bank) * 1.33 --> 133 cf (truck) / 1.06 --> 125 cf (fill slope)

I can apply the cut factors as shown, but what factor am I going to use for the Fill?  If I know the ratio of the two source materials then I could calculate a "blended" fill factor but in this case the ratio changes along the length of cut.  As I noted earlier the workaround solution is to combine the swell and shrink factors for each material, and apply them to the Cut only.

The issue may be further complicated if borrow and waste sites are introduced to the masshaul calculation, as there is no way to factor those quantities.  We avoid this by not including them as pay items.  Everything is calculated and paid as unfactored bank volumes in the road section.

Steve
Please use the Accept as Solution or Kudo buttons when appropriate

[fcernst]

I can apply the cut factors as shown, but what factor am I going to use for the Fill?  If I know the ratio of the two source materials then I could calculate a "blended" fill factor but in this case the ratio changes along the length of cut.  As I noted earlier the workaround solution is to combine the swell and shrink factors for each material, and apply them to the Cut only.

Don't put Rock and Earth in the same Material. Use Gaps if needed in these Material Lists.

Once you do this, using your numbers now, the Fill factor for the Rock is 1/0.94 = 1.06, and the Fill factor for the Earth is 1/0.52 = 1.92

Leave the Cut Factors alone, and just where they need to be represent the excavated expansion volume. 

...First of all the Refill factor can only be used when the material type is set to Cut and Refill. 

The Refill Factor works for Cut and Earthworks materials also. 

[sboon]

The Refill Factor works for Cut and Earthworks materials also.

It may change the values in Resuable columns of the tables but it does not change the Net volumes or the masshaul.  In the volume report that you posted yesterday the Cumulative Net Volume is a product of the Cumulative Cut and Cumulative Fill, not the Cumulative Reusable.

Steve
Please use the Accept as Solution or Kudo buttons when appropriate

[fcernst]

No, I noticed that too. I should have mentioned it..I was trying to emphasize how the software is designed to be used.

Also here in 2015, the Refill Factor is used, but the dialog box goes blank after entering the value.