TERRACE
MINING
OPTIMUM EXCAVATION STRATEGY
You
are on the site WWW.GEODIS-ALE.COM
This
note deals with the geometrical facet of the cultivation of a terrace
quarry as performed by the software ALE Advanced Land Editor.
ALE
suggests several work tools. Some of these tools are automatic up to
the design of a quarry in 3d mode by a single command or "wish".
Other commands allow local adjustments.
Cultivation
Strategy
The figure A shows the grey section of an
hill side to be excavated.
The red line in the same section is the
track of the final average slope of the quarry.
The main problem
is to set a cultivation strategy to go step by step to the final
result.
The figure B shows
an excavation from down to top in such a way to get a service
platform for moving materials and other operation. Following this
strategy you will soon generate an high step and will be forced to
move upward the excavation front line. You see that working this way
a possible rolling stone can land on the service platform with danger
for persons and materials.
The figure C shows an excavation here
and there along the hill side in such a way to progressively increase
the slope up to the final result. It is evident that the above danger
is still there and is also increased.
The figure D shows an
excavation from top to down by terraces. A small service platform is
first generated at the maximum elevation and than is increased and
moved downward.
Let us suppose to choose the last strategy. We
shell still choose an elevation step and a width of each terrace. The
note Cultivation
of Terrace Mining deals with this problem..
Automatic
Modelling
Note that the above considerations have
been done on a single section whereas the mining may be developed on
a large and complex shape. The strategy is clear but the design needs
a long work to get a large number of cross sections and develop the
cut volume calculations.
The ALE Advanced Land Editor program
elaborates a single stage project (see next figure) and automatically
generate all the design documents (maps, sections, calculations, 3d
views) for each progress terrace. Of course this is a suggestion
because no software can substitute the expertise of a qualified
professional engineer.
Let us observe the work steps.
The next figure shows a territory and an boundary line to select the
area to be cultivated.
ALE
provides a card where you should indicate the elevation step, the
width and the maximum angle of the terrace.
Starting from these
data, a window immediately shows the calculated average slope of the
quarry.
It is possible to select a normal orizontal terraces
quarry or an inclined terraces one.
Now ALE shows a summary of the proposed design :
Then ALE automatically generates the final design going step by step from the top to down :
Optimum
volume
Making reference to the fist figure of this
note, you see that it is hard to get a larger excavation volume using
the same design parameters. As ALE make the same work in the 3d space
the proposed shape is neat to an optimum.
Management
of the Project
ALE adds power but allows
a large freedom.
Any parameter of any single terrace of the
quarry may be managed and changed. Also the map shape of each terrace
may be edited as a polyline. The project will be immediately updated.
In-between Configurations
As ALE
generates the project step by step, the design documents (maps,
sections, volumes, 3d views) are available for the in-between
configurations.
The next figure shows the configuration following
6 out of 10 terraces.
Calculation
of the Excavation Volumes
The method to calculate the cut
and fill volumes both by cross sections and by prisms is illustrated
in the note Calculation
of Cut and Fill Volumes.
Evaluation Version
An evaluation version may be downloaded from the following site.