Dirt Work Quantites/Volume Reports

[thomasbothun11]

Hello,

I have been going back and forth with coworkers about the proper way to calculate borrow quantities for a project while applying a "Shrinkage factor". In C3D it allows you to enter a "Fill Factor" when computing earthwork volumes. I have been told different numbers to apply for the same "Shrinkage Percentage". For example if I am assuming a shrinkage percentage of 30% for a project. What would my "Fill Factor" be in C3D? Would I use 1.30 or would I apply the 1/(1-.3) equation to convert from Compacted Volume to Bank Volume which would in return mean my "Fill Factor" would be 1.42 approximately. Please let me know as this can influence a large borrow volume by quite a bit.

[ecfernandez]

Hi @thomasbothun11, welcome to the Autodesk Civil 3D forums. This is a very interesting question. I will provide a few comments about this process:

The best approach to knowing which factor should be used is to estimate the volumetric variation coefficient. This will show you how the material behaves when compacted/not compacted. It should be estimated for every kind of soil/material, and it is computed when going from a non-compacted to a compacted state and vice versa. This means you should count on both estimations directly from a lab test.

For cut condition, every material we cut will have a different value for volumetric variation. Similarly, depending on the design of our embankments, we might have different values, too. Depending on the composition of embankments, it can be determined if a portion of the cut material can be utilized or if the materials are bought from a quarry.

When we do not have these values but are required to make an estimation, all the materials can be treated as similar, to make things easier. We could say, for example, that it would be the same to shrink a cut material to 0.75% of its volume and maintain fill volumes with no changes as to have 33% of our fill volumes expanded, meaning that 1 cubic meter of embankment would need 1.33 (1/0.75, which is the same than you posted) cubic meters of soil.

With the help of a geotechnical engineer, you should be able to define how many kinds of soil your project is affecting, if you require to separate the computation of each material, or if they have similar characteristics so they can be computed with the help of a simple estimation of expansion/shrinkage of fill/cut materials. Similarly, you should be able to know how embankments are designed.

All these considerations will affect the mass haul diagram. The first material compensation is on the cross-section; then, we evaluate the overhauled quantity. Therefore, being precise with these factors is crucial to estimating the material overhaul for the project accurately.

I hope this helps. Best regards!

[lim.wendy]

Hi Thomas,

Thank you for submitting your question in our discussion forums. I see you are visiting as a new member of the Civil 3D forum. Welcome to the Autodesk Community! Have you had a chance to review the suggestions Camilo provided? Camilo, thank you for taking the time to provide such detailed guidance.

Please let us know if you require further assistance. 

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