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Elevation warning


Miguel Coelho

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Hi

I'm busy simulating a small level of a mine ( a micro model).

I have connected the intake and exit of the level as connected to surface.

I have the surface set as follows, this is the surface design values.

image.png.520af55fab39da7fdcbb9ec3346a3edd.png

When the simulation runs it calculates the correct VRT and I have included a fixed point to correct for that specific levels input temperature.

However every time I run the simulation the message box as below appears.

image.png.e89fc98be19605371f3c9793082d08b4.png

 

I don't want the message box to show each time as it to click Yes and then your simulation results will be different.

So I  then edited the BP for the depth of the level, adjusted the surface datum of mine grid and set the Surface rock datum temp to start at that levels VRT.

The message box then falls away and the density and VRT are still correct.

Is this the best approach when working with micro models of a larger mine?

Thanks

MC 

 

 

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Hi Miguel, if this warning is appearing it means that the surface datum elevation above sea level and the surface datum of minegrid do not make sense with the actual coordinates of the airways in your model. 

According to the warning, the highest elevation (on the mine grid) in your model is 1437 metres, on airway with index 934. If your surface datum of mine grid setting is 4022.5m, then this would imply that the highest elevation airway in your model is at a height with reference to sea level of 1437 - 4022.5 + 237.9 = -2347.6 m? Is this what you want? If so, then it is unusual, so Ventsim is providing the warning. If it is correct, then I suggest you add another undetached airway that vertically climbs to 4022 metres on the minegrid. This will avoid the warning. 

If it is not right, then you may have misunderstood the mine grid setting, which is a common error in Ventsim. The setting Surface Datum of Mine Grid is the elevation in the model at which the surface datum condition is applied, one of those conditions being the Surface Datum Above Sea Level. To check you can go to the Info tab of the Edit Box on an airway and this will provide you with the airway elevation and the elevation with respect to sea level. 

image.png.38dcad7dc200e8406343807cb39aa966.png

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