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Quantity of earthwork

Quantity of earthwork

Quantity of earthwork

I am Civil Engineer, and working as Jobworker for Govt.
I want tips for calculating cross sectional area of earthwork in embankment or cutting.
I have R.L. of center and any three or four point on both sides of center.
and one center line level of cener and side slopes
so I want to find a point autometic where the line of initial level and down/upper line of fomration cut the inital levels .

RE: Quantity of earthwork

You are asking for someone to provide you with a solution; can you do it manually?  If not, then you don't need a computer!

I'm a civil engineer, too.  (For you non-civil types, geotechnical engineering is a specialty within civil engineering.)  Create a spreadsheet with the five columns of input of cross-section, then imitate the manual expresion in the sixth cell.  This should be a pretty basic calculation, unless you haven't told us about some exotic requirement.

If you left something out of your question, then post it following my response.

RE: Quantity of earthwork

My interpretation of the question (as screened by my knowledge of road design):
The given information is the existing ground cross section, expressed with points of elevation and distance right or left of centerline. Then you have a design road cross section, which is a level surcace of a given width, then side slopes that go up or down at a given slope to intercept existing ground. Now, at what points do these side slopes intercept, in offset from centerline and elevation?

I'm sure there's a way to enter appropriate formulas (geometry) and produce something in a spreadsheet. Myself, I would draw it up in cad, maybe automate with lisp, and get the results that way. Also would have a nice visual for checking.

RE: Quantity of earthwork

One 3D CAD package that will calculate volumes, masses and centres of gravity for you is called ProDesktop. It should be available free to download from www.ptc.com (I don't know the exact link, though the ProEngineer forum on this website might be of more help).

The tutorials that come with it are quite helpful and you should be able to build reasonable 3D geometries in a matter of hours. If you have really complex geometry, you'll hit the limits of the package quite quickly though.

It will give you the ability to perform quick checks and display visual results though. One problem that we did run into with the package is that if you draw everything to scale the package runs out of memory very quickly. This is because it's designed to draw small engineering components. If this happens to you, you'll have to scale what you're drawing - Using mm instead of m should solve any problem like that.

RE: Quantity of earthwork

Pull out your surveying book - there is a hand calculation technique for calculating the area of irregular figures.  I haven't used it in over 20 years, but it has to be simpler than a cad package!

RE: Quantity of earthwork

Any decent survey textbook will provide you with the formula for doing this by a hand calculation. It’s the same formula for calculating areas of a traverse given coordinates. (Latitudes and departures)

Simply use basic excel formulas to do this on your electronic data to eliminate and arithmetic errors.

Rick Kitson MBA P.Eng

Construction Project Management
From conception to completion

RE: Quantity of earthwork

It would be fairly simple (maybe tedious depending on number of points of survey) to do with a cad package and if you use solids in autocad you can use the massprops command to give you the volume (along with mass if you have set the right var for density and centroid and moments of inertia and others).

Draw out all your points from your survey at 0 elevation. Draw out triangles between points with plines (your surface will be a triangular representation). Lets say all the elevations of the points are from 20'-40' above a baseline. Extrude all the plines with a length of 50' (above any survey points). Move all your survey points to correct elevations. Use the slice command to slice each extruded pline. Union them all together and there is your existing slopes.

For the roadway its very simple. Draw a cross section (the bottom would be your road, let say at an elevation of 10' and then slopes and then a top with elevation same as you had extruded your existing ground plines) with a pline. Draw a pline for the path. Extrude the cross section along the path. There is a solid of the roadway.

Use the intersect command  and the two solids. The remaining is your cut soil. Use massprops on that to find volume.

If your road is straight you should be able to do it easier in a spreadsheet, but if it has curves it is harder in a spreadsheet to take into account the larger circumfrence/volume on the outside of a curve and the smaller on the inside.

Much of the autocad can be automated with lisp as well.

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