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Planning of blasts and rock mass characterisation
 at the same time!

White paper
Demo software

 
   
 

BlastMetriX3D is an innovative system for bench face surveying and planning of blast layouts based on three-dimensional images.

After setting some so-called marking elements (scaling rods) two photos are taken using a digital SLR camera previously calibrated by 3G Software & Measurement.

From the photos a three-dimensional image of the bench face is generated by purpose built software. The result is a metric 3D image representing a dense three-dimensional survey of the rock surface. Using another software component the geometry of the blast is planned and plan views for documentation purposes are generated.

   
 
 

Figure 1 : The BlastMetriX3D principle: from two pictures (1) a 3D image
(2) of the bench face is computed from which a drill pattern is planned
and the resulting burden is shown over the whole area (3),
as well as profiles (4) and plan views (5) are gained.

   
 
 
Figure 2 : Taking pictures of a bench face using a calibrated SLR camera.
 
  Features
 

Once a 3D image of a rock wall is ready it can be interactively inspected with the BMX BlastPlanner software and the blast can be planned. By telling the software some fundamental geometric parameters of a blast such as burden, side spacing, or desired inclination of bore holes, each bore hole gets automatically the rock volume to blast and an according profile.
The computed bore hole positions are provide in a plan view.
As the three-dimensional shape of the rock wall is known precisely, profile can be extracted at arbitrary locations. The main advantage here is that an assignment to nature is easy as the profiles are accorded with an image.

   
 
 

Figure 3 : The coloured representation of the minimum burden over the whole bench face
area allows an adaptation of the drilling plan and/or the loading.

   
  Measurement procedure
  Preparation: the desired blast layout is entered into the software (burden, side spacing etc.). These magnitudes can be changed at any later point in the processing.
 
  1. Establishment of the delimiters on the top of the bench face
  2. Placing some panels to indicate the bottom level
  3. Taking a stereoscopic image pair (one after another, freely positioned)
  4. Transferring the images on a (supplied) notebook computer
  5. Generation of the 3D image with the 3D software
  6. Inspection of the result and planning the blast
   
 
Use of results
 

From the acquired 3D image (see Figure 3) of the bench face a drilling plan is derived.

The position of the single boreholes is provided as measures related to a reference line that is the connection between the delimiters, thus borehole positions can be located just by using a tape measure. Each borehole gets its according profile of the bench face and the volume to blast (see Figure 4).

   
 
 
Figure 4: Bore hole positions can be located just by use of a tape measure.
   
 
Figure 5: Each borehole gets geometric information, such as course of burden, volume to blast.
  From the acquired detailed 3D surface an optimal borehole plane that meets the required burden best can be determined.
References to the nature are easy as the geometric information is not represented by an abstract triangular mesh only but rather by an image with a 3D surface mesh in the background (with x, y and z coordinates in either absolute or relative co-ordinates).
   
 
 
Figure 6: Comparison of the profile with the according minimum burden diagram of the same borehole.
Depending on the geometry of the bench face there are differences in the decimetre range.
   
  Time need
 
The time need from taking the photos, generating the 3D image, up to getting a borehole plan is less than one hour (typ.). In required processing can be done on site (in a car) on a mobile computer provided that the whole blast geometry was acquired with a single 3D image.
   
 
  Figure 7: The elements of the BlastMetriX3D system.
   
 

Main benefits at a glance:

  • Simple application (taking pictures)
  • Mobile contact-free rock wall measurement without requiring surveying skills or instrumentation
  • Optimisation of blast design by having profiles and volume to blast for each borehole
  • Objective and complete documentation of the bench face
  • Localisation of boreholes just by using a tape-measure
  • Increase of safety
  • Reduction of fly-rock and vibrations
  • Cost effective