This command calculates the total volume cut from a pit and the volume of a strata cut from the pit. The program requires two closed 3D polylines that represent the top and bottom of the pit. The top surface for volume calculations is modeled by the top polyline and any points in the bottom polyline that are outside the top polyline. Likewise the bottom surface is modeled by the bottom polyline and any points in the top polyline that are outside the bottom polyline. The top and bottom polylines are used as inclusion area polylines to limit volumes to within these polylines.
The program also processes two grid files that define the top and bottom of a strata. This volume is calculated between these two grids. This volume is the amount of strata cut from the pit. The inclusion area for the strata volume is the bottom pit polyline. The program assumes that the strata is entirely above the bottom of the pit and below the top of the pit.
This example shows a pit that is advancing from left to right.
The left side of this pit was the edge of the previous pit.
Example top and bottom of pit closed polylines
Select closed polyline of pit Top: pick a closed
polyline
Select closed polyline of pit Bottom: pick a closed
polyline
Make Grid File Dialog Choose a grid resolution.
Select Top of Strata Grid Choose .grd file that models the
top of the strata.
Select Bottom of Strata Grid Choose .grd file that models
the bottom of the strata.
Enter density of strata (lbs/cf): 75
Top of pit area: 31390.12 S.F.
Bottom of pit area: 31390.12 S.F.
Total cut: 1199184.98 C.F., 44414.26 C.Y.
Other cut: 810572.37 C.F., 30021.20 C.Y.
Strata cut: 388612.60 C.F., 14393.06 C.Y.
Strata density: 75 (lbs/cf)
Tons of strata: 14572.97
Strip ratio (C.Y. other/Ton strata): 2.06
Pulldown Menu Location: Surface
Keyboard Command: dragpit
Prerequisite: Two 3D polylines for top and bottom of pit and
two .grd files for the top and bottom surfaces of a strata.