Pit wall pushback
You can use this function to examine what happens when either:
- The pit walls are pushed back by a specified distance, or
- The berm widths are changed thus altering the overall slope of the pit.
To run this function: Choose Design > Pit design > Pit wall pushback, or...
The function operates on previously developed toe and crest files from Pit Design. It moves any point on the pit walls that is inside a 'shift envelope' string. You can create a shift envelope string in Graphics to enclose, for example, some material missed by the previous pit generation. When the envelope encloses the entire pit all walls are affected.
You can use PIT WALL PUSHBACK to examine waste dump expansion.
Fields on the Pit wall pushback form
| Field | Description |
|---|---|
| Define the existing volume outlines | |
| Location | The string file that contains the existing toe and crest outlines which you will modify. |
| Define the new volume outlines | |
| Location | The name and file path for the string file you want to store the new toe and crest outlines, with pushed back walls. |
| Identify change envelope | |
| Location |
The location of the boundary string you want to use to define the limit of the pushbacks. The boundary string must be a closed segment, and must be the first segment of string one. To use push backs for the whole pit you need to chose a boundary envelope that surrounds the entire pit. |
| Shift or change? | |
| Parallel | If you select this method of pit wall modification the pit walls are pushed back by a specified distance. |
| Berm | If you select this method of pit wall modification the berm width is changes to change the overall slope of the pit. |
| Parallel shift | If you choose Parallel pit wall modification, this value is the distance the pit wall outlines are shifted. A positive value indicates outward shift, a negative value indicates inward shift. |
Output
The crests and toes of the pit are changed in the new volume outlines file.
Tip: You can calculate the tonnage and grades if you intersect the ore and waste by the new outlines using POLYGON INTERSECTION, and then pass the result through STRING FILE VOLUMES function.