Define Pit/Dump Regions

To access this screen:

Design ribbon >> Pit Modelling >> Define Slopes.
Design ribbon >> Dump Modelling >> Define Slopes.

This panel is used for the definition of both pit and dump slope and berm width regional settings. Unless otherwise stated, the terms pit and dump are synonymous, as are bench and lift.

This panel is used to extract, edit and define the slope specifications for your pit or dump.

As with all managed tasks, updates made on this panel are committed to your project using the Save (1) or Save and Close (2) buttons at the top of the form. You can also Close without saving (3).

Note: This panel is used for the definition of both pit and dump slope and berm width regional settings. Unless otherwise stated, the terms pit and dump are synonymous, as are bench and lift.

Note: Reducing the grid spacing for boundary string slope control will increase the processing time required for generating design strings in the Auto Design tasks for pits and dumps. This is because more points of influence need to be considered during blending between regions.

Rosettes

Slope regions can optionally include one or more rosettes. Rosettes comprise a location and a set of azimuths each of which has a set of the three standard control values (face angle, standard and catch berm widths).

Rosettes have a minimum and maximum elevation to define their volume of influence. The horizontal influence of a rosette covers the entire slope region in which it is contained.

Each rosette is given an X, Y location. The X, Y location is only used when multiple rosettes are being used to interpolate the projection values a string point.

How Rosettes Work

When using a single rosette to determine the projection control values at a point, the direction azimuth of the projection is used to locate the corresponding azimuth in the rosette. The X,Y location of the rosette is NOT used. The elevation constraints are always used.

In the diagram below a circle is being projected using the rosette parameters in the table. If a point is being projected at an azimuth of exactly 0⁰ the berm width is 10. If a point is projected at an azimuth of 220⁰ the berm width is 30.

There is a gradual change in berm widths between the specified azimuths. If a point is being projected at 290⁰ the berm width will be 15, i.e. mid-way between 0 and 30.

Face angle values are determined using the same methodology for berm widths as described above.

Multiple Rosettes and Interpolation of Control Values

For pits or dumps in more advanced stages of design it is common for slope regions to contain at least one rosette, for example to force temporary internal walls to have a shallower angle than final walls which due to their longevity warrant the extra cost of being blasted using pre-splitting.

For more complex geotechnical configurations, or perhaps in an early study using a single default slope region, multiple rosettes may be used. In this case an interpolated value at a projection point is calculated by using each of the relevant rosette values.

The influence of each rosette can be adjusted by assigning it an inverse distance weighting (IDW Power value) which is used in the interpolation. If no IDW Power value is assigned then nearest neighbour interpolation is used.

Rosettes Reminders

The X,Y location of a rosette is only relevant when interpolating values from multiple rosettes.
The direction of projection of a point is used to determine the corresponding rosette azimuth values. A single point on a design string may have up to 2 projection directions: one for each of the adjacent edges.
The X,Y location of a rosette may be outside the volume of the slope region in which it is being used.
Each rosette belongs to a single slope region

Define Regions

Activity steps:

Display the Define Pit/Dump Regions screen.
Select the Pit or Dump to which the current slope region definition applies.

If defining pit regions, this list contains all pits defined using the Reserves ribbon's Manage task. If defining dump regions, this list contains all dumps defined using the Define Dumps task.
Define the Region Reference – regions are defined using data from either of the following:
- Manual – Regional information is entered manually and not derived from planning data.
- Planning Model – Region IDs are extracted from unique values of a the assigned planning model's Region ID attribute.
- Boundary Strings – Define a regional grid using a boundary string. Select a loaded string File and a Region ID. You also need to define the Grid Spacing to isolate grid regions.
Region (table) – This table is used to define each slope region within the nominated pit, and for each region the corresponding face angle, berm width and (optionally) inter-ramp angle value.
Review and edit the Bench/Lift Constraints table, containing the following columns:
- Region – A unique label representing a slope region. A DEFAULT entry will always exist and must have (at least) Face Angle and Berm Width defined. Alphanumeric string.
- Face Angle – The angle formed by connecting the crest of a pit bench and the toe of the bench immediately below. This will be dictated by rock strength, structural fabric and blasting parameters.
- Berm Width (Standard) – the distance between the toe and crest of a bench.
- IR Angle (Standard) – Only displays if Show inter-ramp angle is checked below. This is the angle between the toe of a slope where a ramp segment passes and the toe of a bench located immediately upwards. Only displayed if the Show inter-ramp angle... check box is selected.
- Berm Width (Catch) – The catch bench (“CB”) or berm is used to catch spalling rock and prevent it from rolling down the pit wall, creating a safety hazard. A rule of thumb is that the catch bench width should be according to the formula 4.5m + 0.2H, where H is the height of the bench. This means the recommended catch bench width for a 5m high bench should be about 5.5m; for a 10m high bench it should be 6.5m; and for 15m high bench it should be 7.5 metres.the distance between the toe and crest of a bench.
- IR Angle (Catch) – Only displays if Show inter-ramp angle is checked below. For any catch bench, the angle between the toe of a slope where a ramp segment passes and the toe of a bench located immediately upwards. Only displayed if the Show inter-ramp angle... check box is selected.
Note: If regions have been manually-defined, they may be deleted using the red cross at the end of their row. If regions have been extracted from the planning model or boundary string file, they cannot be removed using this panel; these edits will need to made to the specified model or string file beforehand.

Note: A DEFAULT value is always present - this can be considered the "pit- or dump-level" slope definition, which will be used for all pit benches that are not allocated to any other pit region/rosette or manual override. A pit or dump must have default values for Face Angle and Berm Width as these values will be used in the absence of other regional slope information. In fact, you cannot save the task unless the DEFAULT table row contains numeric data entries in these two columns. Catch berm widths are optional.
Review the Selected Region Rosettes table. When a region is selected, its current rosette information (if any) is listed here. New rosettes may be explicitly added by typing into the empty first row. All entries in the rosette are editable. X and Y can only be numeric. Z Min and Z Max can be numeric or absent.
- IDW Power – The "strength" of a rosette relates to the size of the zone over which it can influence slope angles and/or berm widths. The higher the value, the larger the zone of influence the specified rosettes with a particular region will have. Negative values are not permitted.
  
  In other words, the influence of each rosette can be adjusted by assigning it an inverse distance weighting (IDW Power value) which is used in the interpolation. If no IDW Power value is assigned then nearest neighbour interpolation is used.
- Add from View – Allows a new rosette to be created at a location selected interactively in the 3D or Design views.
- Select from View – Will display indicators for all the rosettes in the 3D or Design views, and allow the rosette to be chosen by clicking on the indicator in the 3D or Design view.
- Selected Rosette Details – For each rosette, define:
  - Azimuth
  - Face Angle
  - Berm Width (Standard)
  - IR Angle (Standard)
  - Berm Width (Catch)
  - IR Angle (Catch)
  See regional parameters for an explanation of each property.
- Top-down or Bottom-up radio buttons change the visualization accordingly.
  
  Note: Top-down assumes a circular pit or dump rim and berm offsets, face offset and impression of the pit bottom. Bottom-up starts with a circular pit or dump base and works up to a non-uniform pit rim.
- Bench Height – Edit this integer to see the impact of differing bench or lift heights on the rosette projection above - note that this will not adjust the existing bench table - it is purely illustrative.
Save your task settings.
Save your project.