Blast Wizard

This dialog box provides context sensitive help.

Introduction

The Blast Wizard allows reshaping of 3D terrain by a blast. Users draw the blast toe and the desired blast profile. They then nominate a Pit Shell Surface and a swell factor. Terrain is automatically reshaped to match the profile's shape and balance volume. Local mass balance is carried out at user-specified intervals. This avoids any transport of material along the length of the blast.

Three parameters control the shape of terrain around non-straight regions of the toe: Corner Heave, Corner Throw, and Relative Corner Width. These parameters allow users to control the way the blast shape is calculated in non-straight regions of the toe and transition zones to unblasted terrain.

Use of the Blast Wizard is described in detail in new documentation. This documentation may be downloaded from the Earth Technology internet site.

The Blast Wizard Dialog box allows users to control how the program creates an emulation of blasting. The design of the blast requires the user to create the following design elements:

•Pit Shell. This is the surface defining the strip which is subject to blasting.

•Blast Toe. This is a linear feature which runs along the length of the blast. It is located at the toe of the blast face (typically the bottom of the pre blast highwall).

•Typical Blast Profile. This is a two dimensional profile, drawn in a Section Window, which is typical of the shape of the blast.

When the Typical Blast Profile is complete 3d-DigPlus applies it at regular stations along the length of the blast. The spacing of the stations is determined by the user. At each station the in-situ volume is calculated. The section is moved up and down as required to match the in-situ volume with blast swell applied. Three dimensional volume calculations are used. In this manner volumes are preserved locally and a surface is generated consistent with the user defined Typical Blast Profile. A texture can optionally be applied to the blast surface.

The following is a description of the items in the Blast Wizard dialog box.

Items in the Blast Wizard Dialog Boxes

Select Feature Dialog Box

Select Toe Button

Press this button to select a portion of the desired feature and to set direction of blast. Remember that the selected part should cross the section in which the two-dimensional blast profile will be drawn. Then press Next button.

Next Button

Press the Next button to call the next Blast Wizard Dialog box.

Help Button

Click this button to show the context help for the Blast Wizard dialog box.

Cancel Button

Click this button to close the dialog box with no action.

Set Parameters Dialog Box

Pit Shell

This is the name of the inner surface defining the strip which is subject to blasting.

Section

Select the cross section that will be used to design the blast profile. This section needs to be close to 90 degrees to the pit axis and long enough to cover strip to be blasted. The section line should cross the selected part of the Toe feature.

Section Window Height Scaling group.

In order to assess the blast profile as designed it is best if the cross section is in Proportional mode (no vertical exaggeration). This mode may be set in this group if it was not done in advance using Utilities/Vertical Section Settings… option.

Proportional

Select this radio button to set Proportional mode.

Fit to Window

Select this radio button to set Fit to Window mode.

Calculation group

Split Size

This is a desirable spacing of the stations. At each station the in-situ volume is calculated. The real spacing may differ from the specified value so that all stations have the same size. The Split Size parameter does not affect the size of the “corner stations”.

Transition Zone Size

This is the size of side areas that are out of the selected portion of the Toe feature. Some material may also be thrown into these areas. This parameter controls how much material is thrown outside the selected Toe.

Corner Shape group

The specified portion of the Toe feature may be not just a straight line i.e. it may contain inner or/and outer corners.

At an inside corner the thrown blasted volume reports to a smaller length of void than in a straight section of the blast. At an outside corner the thrown blasted volume reports to a larger length of void than in a straight section of the blast. These geometric effects result in the heave and throw in the region of a corner differing from that specified in the design blast profile.

If the one blast simulation design (profile plus blast wizard parameters) is applied to the entire blast area, including corners, the result will often reflect the expected blast behaviour. More throw will occur at outside corners and less at inside corners.

If the actual blast design in the pit is intended to compensate for the corners the blast wizard corner parameters may need to be adjusted to reflect this.

Relative Corner Width inner

This parameter changes the relative size of corner areas (stations) in which the in-situ volume is calculated. The angle of the corner and the profile size give some default dimension of the corner station. The Relative Corner Width allows the user to correct the default value. For instance, the value 1.1 gives a corner width that is 10% larger than the calculated one.

Corner Throw inner

This parameter changes the throw distance in inner corners with respect to the straight parts. The parameter is relative i.e. a value of (say) 1.1 gives a throw distance 10% longer than in the user-defined profile.

Corner Heave inner

This parameter changes the corner heave in inner corners with respect to the straight parts. The parameter is relative i.e. a value of (say) 1.1 gives a throw distance 10% longer than in the user-defined profile.

Relative Corner Width outer

This parameter changes the relative size of corner areas (stations) in which the volume in-situ is calculated. The angle of the corner and the profile size give some default dimension of the corner station. The Relative Corner Width allows the user to correct the default value. For instance, a value of 1.1 gives a corner width 10% larger than the calculated one.

Corner Throw outer

This parameter changes the throw distance in outer corners with respect to the straight parts. The parameter is relative i.e. a value of (say) 1.1 gives a throw distance 10% longer than in the user-defined profile.

Corner Heave outer

This parameter changes the corner heave in outer corners with respect to the straight parts. The parameter is relative i.e. a value of (say) 1.1 gives a throw distance 10% longer than in the user-defined profile.

Texture group

Add Texture check box

Check this box to add some “noise” (irregularity) on the blasted surface to make its appearance more natural.

Texture Ratio

This parameter specifies the portion of blasted material to be used in creating the noise texture on the blasted surface. The default value is usually 0.03 i.e. 3% of total blasted material is dumped chaotically on the smooth model surface.

Max. Height

This is a maximum elevation of the randomizing noise texture.

Use Cut Only Polygon check box

Check this box to use the Cut Only Polygon in the blast model design. This polygon will mark out the area on the high-wall where you know that only blast removal (cut) will occur.

Select Polygon button

Press this button to set one of the existing terrain polygons as a Cut Only Polygon.

Draw Polygon button

Press this button to draw a new Cut Only Polygon.

Limit by Surface check box

Check this box to restrict the blast by some inner surface. For example, in the case where the pit shell follows the floor of coal select the Limit by Surface and select the roof of coal surface from the list. The blast volumes will now be limited to the area above the coal seam.

Next Button

Press the Next button to close this dialog box and call the Draw Profile dialog box of the Blast Wizard.

Back Button

The Back button to go back to the Select Feature dialog box of the Blast Wizard.

Draw Profile Dialog Box

Target Swell Factor

Here the desired value of Swell Factor is input. This needs to be reasonably close to the Initial Swell Factor, but it does not have to be exact. 3d-DigPlus will adjust the vertical location of the section each time it is applied to ensure the target swell is achieved. If the profile or swell are not satisfactory click Draw Typical Blast Profile again and re draw the profile.

Initial Swell Factor

After the profile is complete the Initial Swell Factor field will report the swell for your section

This is a calculated value of swell factor exactly corresponding to the drawn typical blast profile. Note that the volume calculations are applied only to that station which contains the section where the blast profile was specified.

Draw Typical Blast Profile button

Press this button to (re-)draw the Typical Blast Profile.

Finish button

Press this button to generate the blast profile and close this dialog box.