IB Pattern

Generate Interburden Pattern

The IB Pattern option to create a 2D blast pattern for interburden blasting. This pattern is the basis for creating the blast holes themselves, the survey peg locations and indicators. This pattern should be correct as to hole location, name, and hole specifications prior to continuing on. A pattern is created in a bay-by-bay basis, with each bay having a given number of rows and echelons.

Instructions

  • Select Open Pit menu
  • Select Blast Design submenu
  • Select IB Pattern option

If the Set Up option has not been selected previously in this Vulcan session, the program will ask for a Bay specification identifier first. Either way, the following panel appears and allows the current bay parameters to be modified. This will not modify the specification file, only the bay parameters current for this Vulcan session. To set the parameters back to those in one of the specification files, select the Setup option again, as this always reads the specification file.

Bay specifications panel

The same situation applies here as for the bay parameters. The following panel appears and allows the current hole parameters to be edited. These parameters are encoded into each pattern object and can be edited later to reflect special situations. The parameters on this panel should be those needed for the majority of holes in the pattern so that the editing is minimized.

Blast hole specifications panel

The following panel appears to allow the layout of the pattern to be defined.

Layout specifications panel

A pattern is created in a bay-by-bay basis, with each bay having a given number of rows and echelons. Enter the number of rows and the number of echelons here. The start point reference gives the starting hole name, and must be a valid hole name. The definition of a valid hole name is given in the Basic Operations section at the top of this documentation. An invalid name is flagged by the program and must be re-entered.

The layer details define the layer name and description into which the 2D pattern is placed, and the colour defines the colour the pattern will be drawn in. If the layer entered is currently selected, then the pattern will be appended to that layer. If the layer exists in the database, but is not selected, then you will be asked whether you want to select the layer or replace it.

The Select layer option will automatically select the layer and then the pattern will be appended to that layer. The Replace this layer option will open a new layer and place the pattern in it. The old layer of this name will be overwritten only if the pattern is saved.

The program does a check in the given layer for the highest echelon number in that layer. If the start point reference has an echelon number less than or equal to this maximum, there may be the possibility of duplicate echelons in this layer. This is flagged by the program with the message: 

'Warning - may have duplicate echelon numbers in this layer'

To continue on and ignore the message, indicate Continue. To go back to the previous panel, indicate Cancel.

The 'A' row string is used to define the position of the first row in the pattern. At the prompt, Indicate 'A' row string indicate the 'A' row string on the screen. The following confirm box will appear and the selected string will be highlighted.

Choosing Accept 'A' row will accept that string, whereas Reject will allow another string to be selected.

At the prompt, Select start point of pattern, indicate the start point of the pattern. This point need not lay on the 'A' row, as it is projected perpendicular to the pit bearing to intersect the 'A' row string by the program. This means that you can snap onto a block edge and the intersection of the block edge and 'A' row will be taken as the start point (so long as the block edge string and pit bearing are perpendicular). The following confirm box appears, and the selected point is highlighted

Choosing Accept point will accept that point, whereas Reject will allow another point to be selected.

The bay can proceed in one of two directions that is, basically along the pit bearing or in the reverse of the pit bearing. At the prompt, Indicate general direction of bay, indicate a point in the general direction required and a rubber banded line will be drawn away from the indicated start point to help. The program will determine from this point whether the bay is proceeding forwards or backwards in relation to the pit bearing.

The echelon can proceed in one of four directions that is, basically along the pit bearing or in the reverse of the pit bearing, and either 'up' or 'down' from the start point. At the prompt, Indicate general direction of echelon, indicate a point in the general direction required and a rubber banded line will be drawn away from the indicated start point to help. The actual echelon direction is based on an angle calculated from the arc tan ( burden / (spacing*0.5) ) which is then applied with respect to the pit bearing. The general direction point is then used to select one out of the four possibilities for the echelon bearing.

The current pattern start point may not be the exact point the pattern is to start from. The following panel appears to enable the start point to be shifted parallel to the bay direction from its indicated point. This option would be more frequently required for the 2nd or subsequent bays when the program's calculated start point is not quite correct. The start point shift distance is measured parallel to the bay direction from the current start point, and then projected back onto the 'A' row string to give the new start point.

Shift start point along bay panel

The program now has all the required information to calculate the pattern. The following steps are taken when doing this :

  • The start point is by definition on the ÒAÓ row string and is the start of the first echelon.
  • The first row of the pattern is formed in the bay direction of length spacing * number of echelons.
  • The last row is parallel to the first row at a distance of burden * number of rows minus one.
  • The echelons are produced by projecting equidistant points along the first row to the last row at the echelon bearing giving parallel rows and echelons.

The following panel appears to enable changes so as to make the rows not equidistant along the first echelon :

Edit row distances

Edit the row separation distances that require change and indicate OK. If any entries have been edited, the program must ensure that the total of all entries is equal to the first echelon length. To do this, the first unedited separation entry after the first edited separation entry will be modified to make all the distances add up to the correct length. If all entries have been modified, then an error will occur if the distances do not match the correct length. Either way, the panel will be redisplayed with any program modified entries to ensure it is correct. Indicate OK again to continue on.

The entire pattern is now calculated by rationing out the row separation on the first echelon proportionally on all other echelons. The pattern thus generated is temporarily displayed prior to creating the actual pattern objects. The following confirm box then appears :

If the pattern is OK, indicate Pattern OK, and the pattern will be drawn as actual objects. If the pattern is not OK, then indicate Reject and the row distance panel will appear again to enable changes to be made.

Each pattern hole contains all the hole specification parameters from Step 3. If the default drill bearing is indicated, the drill bearing will be set to the bay direction for interburden holes.

The last echelon of the pattern is not drawn, but its start point is known by the program. This enables a new bay to be generated adjacent to the existing bay, using the existing bayÕs end point as its default start point. This new bay will have a different bay identifier than the bay just generated. See Basic Operations for more information on bay identifiers.

The following confirm box appears :

Continue with identical pattern will return you to the Shift Start Point panel. Continue with resized pattern will take you back to the Define Layout specifications panel, but only allow the number of echelons and rows to be altered and will not require the indication of the 'A' row string, the bay and echelon directions or the start point. Continue with modified parameters will take you back to the Bay specifications panel, but as for the previous option many of the steps are not required the 2nd and subsequent times around. The echelon bearing set as default on the Bay Specifications panel will be those used for the currently completed pattern. This enables the next bay to have the same echelon bearing as the current bay.


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