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Engineering tools for design, analysis and informationmanagement applied to underground drilling and blasting

I. Onederra1, D. La Rosa1, K.Riihioja1 & G. Power1

1Julius Kruttschnitt Mineral Research Centre, The University of Queensland, Brisbane, Qld, Australia

CONTACT:

Italo A. OnederraSenior Research EngineerJKMRC / University of Queensland - Mining ResearchIsles Road, IndooroopillyBrisbane, QLD. 4068 AUSTRALIATelephone : +61 7 3365 5888Facsimile : +61 7 3365 5999Email: I.Onederra@mailbox.uq.edu.au

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Engineering tools for design, analysis and informationmanagement applied to underground drilling and blasting

I. Onederra1, D. La Rosa1, K.Riihioja1 & G. Power1

1Julius Kruttschnitt Mineral Research Centre, The University of Queensland, Brisbane, Qld, Australia

ABSTRACT

In underground mining, the often unpredictable variability in ground conditions maylead to the application of sub-optimal drilling and blasting patterns, resulting in poorperformance. Experience and pertinent information to develop and implementimproved drilling and blasting strategies can be easily lost due to the lack of means tohelp engineers store, access and manage this information.

The Julius Kruttschnitt Mineral Research Centre (JKMRC) through a series ofindustry funded applied research projects has been developing a system that canfacilitate the drill and blast design, analysis, auditing, documentation and datamanagement processes. The system is a hybrid between an information managementsoftware module called BMS (Blast Management System) and two design andanalysis modules, 2DRing for underground production blasting activities and 2DFacefor development blasting activities.

A concise description of the software tools and its applications are given in this paper.Opportunities to further develop the software are also highlighted, they includeoptions to integrate these tools to existing drilling and blasting automation systemsand portable computing technology to facilitate the design, implementation andcontinuous improvement processes.

1 INTRODUCTION

In underground drilling and blasting, the design and implementation process requiresa good understanding of the geotechnical conditions and the expected response of therock mass to the final excavation. The definition of domains is essential for theestablishment of preliminary drilling and blasting parameters. As our understanding ofthe conditions increase, designs can be continuously improved to achieve betterresults. This iterative process requires a system that can help engineers organise andmanage key information such as geotechnical conditions, blasthole geometry,explosives, initiation and priming systems, initiation sequence, delay timing andoverall results such as fragmentation, rock movement, over-break and damage. Thispaper describes a software system that addresses the above requirements.

The software system has two distinct applications. The first is to capture drilling andblasting experience through the use of databases as a common storage medium forblast design information, and the second is to apply simple modelling and blastsimulation techniques to enable continual improvement of the drill and blast designcycle. The software has not been designed to replace good engineering judgement, but

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rather provide assistance in the analysis and management of information such as fieldobservations, trials and monitoring.

2 THE JKMRC BLAST MANAGEMENT SYSTEM, 2DRING AND 2DFACEMODULES

The blast management system (BMS), in conjunction with the 2DRing and 2DFacemodules, allow engineers to keep track of all the information associated withunderground drilling and blasting practices, that is, both production and developmentwork respectively. The modules are Windows based, using relational databases as thedata storage facility and Microsoft Access for the database engine. The softwaremodules have been designed in such a way that for those familiar with Windowsapplications, little training is required.

The type of information that can be stored and managed by the combined use of theabove modules, include: geotechnical details; drilling and blasting designs such ashole types; diameters; length; location; explosive details and quantity; details of firingsequence; cost information; blast results in the form of reports; photographs;fragmentation assessment data and vibration monitoring data.

A brief description of the main features of the BMS, 2DRing and 2DFace modules isgiven in the following sections.

2.1 The Blast Management System (BMS)

The BMS is an object based database management system which uses a hierarchicalor "parent and child" approach to store information and specify relationships to otherdata (La Rosa & Chitombo 1999, La Rosa 2001). The BMS is currently used by theJKMRC as the platform for the management of drilling and blasting informationwhich include other design modules such as 2DBench for open pit bench blasting(Onederra et al. 2001a). Currently the BMS platform and the drill and blast designmodules form part of a single package called JKSimBlast (Higgins 2002).

Although the management system BMS and the design modules 2DRing and 2DFacecan be operated independently, both design modules are recommended to be run fromwithin the BMS, thus forcing the user to keep track of designs in relation to itsgeotechnical environment and specific results. The BMS uses a tree structure todisplay objects and their position in the hierarchy and the 2DRing and 2DFaceprograms contain the required design and analysis tools. The BMS module also has anumber of other options such as a 3D visualiser, detonation simulation, 3D queryfunctions and reporting functions to aid in the data management and decision-makingprocesses.

Figure 1 shows an example of a typical data tree structure in the BMS. The root nodeis the mining operation and it is then divided into two geotechnical domains; hard andsoft. A domain is primarily defined by the rocks and joints it is composed of and theseare the next two data types in the structure. Ring and development blast collections

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are then added as children of the domains. Results and analysis information of theseparticular designs can also be added to the tree as pointers such as photographs or asspecific data objects such as fragmentation information.

Figure 1. Example of a data hierarchy for the management of drilling blasting information in anunderground operation.

2.2 Ring blasting design editor (2DRing)

As the name suggests, the ring blasting design editor (2DRing) allows engineers tocreate a drilling and charging pattern on a two dimensional plane as if it was beingcreated on paper. However all of the information has three dimensional propertiessuch as the drilling plane, drilling drives, rig positioning and hole orientation.

The design process can be divided as follows:

• Definition of the region to be blasted (i.e. stope outlines);• Definition and orientation of drilling planes;• Definition and location of the drilling drive and rig position;• Blast hole drilling;• Selection and loading of explosives and accessories (down-hole and surface

delays)

This module incorporates a number of features that allow the importation and creationof stope outlines and the definition and orientation of drilling planes and drilling

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drives. Figure 2 shows an example of a typical ring pattern showing the stope outline,a geological boundary, a drilling drive, rig position and drillholes. In 2DRing the useris able to create drill hole patterns with a number of options. The properties of drillholes such as diameter, length, and orientation can be input and changed at any stageof the design process. Options for the charging and sequencing of drill hole patternsare also included to aid in the tracking of explosive quantity and accessories usedduring design. Explosive types and properties are loaded from a "stocks" database.The user is able to create new explosive and accessories stocks for any given supplier.

Figure 2. Example of a typical ring pattern showing the stope outline, a geological boundary, a drillingdrive, rig position and drillholes. The right hand side shows the 2DRing design module and the left the

BMS.

Charging and sequencing information is also used in the program during preliminaryanalysis such as detonation simulations and explosive energy distribution calculations.The BMS can be used to view in three dimensions the design and detonationsimulations carried out in 2DRing (see Figure 3). This is particularly helpful whendesigning multiple ring blasts in large stopes, in pillar recovery situations or massblasts.

Figure 3. 3D viewer and timing simulation with the BMS

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2.3 Development blasting design editor (2DFace).

As in the 2DRing module, the development blast design editor (2DFace) allowsengineers to create a development pattern on a two dimensional plane with threedimensional properties. In this case the design process can be divided as follows:

• Definition of the region to be blasted, in this case the tunnel or drive outline;• Blast hole drilling;• Selection and loading of explosives and accessories (down-hole and surface

delays)

The 2DFace module incorporates a number of predefined tunnel shapes for whichproperties such as width, height and orientation can be set. The program also allowsfor the creation of irregular shapes through the polygon creation tool or theimportation of actual profiles from laser surveys or other mine planning software.

In 2DFace the user is able to create drill hole patterns using single hole drilling andmultiple hole drilling options. As in the 2DRing module, options for the charging andsequencing of drill hole patterns have also been included to facilitate the tracking ofthe explosive quantity and accessories used during design. Figure 4 shows an exampleof a typical drilling pattern created in 2DFace. Details of this module have beenfurther described by Onederra et al. (2001b).

Figure 4. Example of a typical drilling pattern created in 2DFace. The right hand side shows the2DFace design module and the left the BMS.

2.3 Engineering design and analysis tools

The drilling and blasting design and data storage features of the modules arecomplemented by a number of engineering analysis tools, these include:

• Detonation simulation analysis;• Explosive energy distribution analysis;

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• The near field peak particle velocity contouring; and• An image digitiser (2DFace only).

In summary, the detonation simulation tool allows the user to view (in differentmodes) the detonation sequence of the blast and visually assess the design prior toactual blasting. A number of parameters can be defined to simulate the blast,including detonator scatter, number of simulations and frame speed.

The explosive energy distribution analysis introduced by Kleine (1988) can helpassess the distribution of the explosive charge in a plane or volume of rock mass. Ithas generally being applied to optimise design geometries and the charging conditionsof ring patterns (Guest et al. 1995, Onederra et al. 1999).

The semi-empirical approach developed by Holmberg & Persson (1980) to estimatenear field peak particle velocities (PPV) has also been incorporated. This engineeringapproach has been widely applied to estimate the extent of rock mass damage and pre-conditioning (McKenzie et al. 1995, LeBlanc et al. 1995, Liu & Proulx 1996, Meyer& Dunn 1996, Villaescusa et al. 1997;2002, Peterson et al. 2001). Near field peakparticle velocity has also been applied in the development of a breakage uniformityindex that forms part of a fragmentation modelling framework for underground ringblasting applications (Onederra 2002).

In the 2DFace module, the image digitiser is a unique tool which has been developedto enable engineers to digitise an image of the face to obtain the "as drilled" collarpositions of a pattern. It also includes features for the digitisation of rock massstructural features. This tool is useful in quality control, performance assessment aswell as for general blast auditing practices.

2.4 General reporting tools

In addition to standard windows printing options, 2DRing and 2DFace contain anumber of other tools that help in the reporting of specific information. These includefor example a dimensioning tool, visibility of objects and properties, design objectsummaries and copying and pasting of data. The latter allows the user to easilytransfer information to other windows based applications such as Microsoft Excel asshown in Figure 5.

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Figure 5. Example of 2DFace data copied into a Microsoft excel spreadsheet

3 PRACTICAL APPLICATIONS - CASE STUDIES

3.1 Development of a fragmentation modelling framework for underground ringblasting applications.

This example describes the application of the system in both the management andback-analysis of information that has contributed to the development of a preliminaryfragmentation model for underground ring blasting applications. The example isdrawn from work conducted at the Newcrest-Ridgeway operation (Power 2001,Onederra 2001c;2002). At Ridgeway, extensive fragmentation assessment andanalysis work was conducted during the extraction of the 5330 and 5305 undercuts.The database has included the analysis of over 400 individual images of drawpointmuckpiles taken at different stages of extraction. Images were analysed using theSPLIT image analysis system (Kemeny et al. 1999).

The fragmentation performance of individual rings was directly linked to the actualdrilling and blasting parameters used in the firing of these rings. Back-analysis ofthese blasting conditions with the use of the BMS-2DRing system allowed for thedevelopment of empirical relationships linking design parameters and rock massconditions to fragmentation performance. Figure 6 gives an example of the "asdrilled" and "as charged conditions" of a typical ring fired in the E3 crosscut duringthe development of 5330L undercut. Results of the fragmentation assessment workconducted on one of the muckpile images of this particular ring are also shown. InFigure 6, the left hand side of the screen shows the tree structure of the BMS withdomains, ring data and other objects such as photographs and muckpile fragmentationdata.

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Figure 6. Application of the BMS-2DRing system for the storage and management of sub level cavingring blasting information.

In this particular application, the BMS-2DRing system did not only provide aconsistent way of documenting, storing and managing information, but also allowedthe back-analysis of ring geometries with some of the engineering tools describedearlier. This facilitated the development of an empirical fragmentation modellingframework. The fragmentation model being developed has already been trialed inassessing the impact of certain design changes and their effect on fragmentation.Results from this model have so far been very encouraging and both calibration andvalidation studies are continuing. Details of the model are discussed in more detailedby Onederra (2002). In addition to fragmentation modelling, the information collectedfrom this study has also helped in reviewing future design practices with the view tominimise the incidence of undesirable outcomes such as brow damage and back-break.

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3.2 Development blasting auditing, analysis and design optimisation at AnglogoldBrazil mines.

As part of the drill and blast continuous improvement process, the Anglogold Braziloperations needed a system that would allow engineers to evaluate their currentdrilling and blasting development practices. The objective was to identify the mainfactors influencing advance rates in "difficult" ground conditions and establishstrategies to achieve best results and hence minimise the cost of advance. The 2DFaceprogram was customised to allow engineers to design, analyse and monitor currentpractices with the view to establish improved standards for specific geotechnicalenvironments (Onederra et al. 2000). The program was also used for quality controlpurposes, to highlight differences between design and implementation and identify thepossible effects that these could have on overall efficiency. Figure 7 shows the imagedigitising tool used to collect information for this purpose.

Figure 7. Example showing the application of the 2DFace image digitiser to collect "as drilled"information of development patterns as well as major rock mass structural features.

Blast monitoring, including VOD measurements and vibration monitoring were usedto complement the analysis conducted with the 2DFace software. The workparticularly focussed on the more difficult rock masses where optimal advance rateswere not being achieved. As part of the monitoring program a decision was taken toquantify the performance of the preferred burn cut geometries.

A preliminary 3D explosive energy distribution analysis of the burn cuts indicatedthat the possible contributor to detonation failures was hole deviation and/or poorcollar positioning. In some cases holes had been collared too close to one anotherresulting in localised high energy zones. This confirmed the importance of accuratehole collaring and drilling. The overall analysis helped define the critical distancebetween charged holes in the burn cut to avoid the incidence of hole dislocationand/or explosive desensitisation. Immediate improvements in results were achieved.Results of the monitoring program were stored in the BMS-2DFace system and couldbe easily retrieved for future reference.

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4 FUTURE APPLICATIONS

The BMS-2DRing/2DFace (also known as JKSimBlast-Underground) systemprovides an immediate opportunity to facilitate the design, implementation andcontinuous improvement process of underground drilling and blasting activities. Thesystem provides a flexible platform which can facilitate its integration with existingdrilling and blasting automation systems such as drill rig alignment and positioningsystems and MWD (Measure while drilling) data acquisition systems.

With the emergence of rugged mobile computing systems such as pen tablets,engineers can now gather digital information in situ. For example by using the imagedigitising tool in 2DFace, engineers can collect "as drilled" patterns and geotechnicaldata at the face. This permits the implementation of up to date and effective qualitycontrol procedures and back-analysis tools which can contribute to theimplementation improved drilling and blasting practices and better match betweendesigns and geotechnical domains.

5 CONCLUSIONS

In underground drilling and blasting as with many other mining activities, thedevelopment and implementation of improvement strategies requires the adequatecollection and proper documentation of data. This paper has introduced theapplication of a software system that facilitates this process by helping engineersimplement a database storage and management system. The system allows thedocumentation of all underground drilling and blasting related information, includinggeotechnical data, design details, implementation, monitoring, analysis and results.

The software can be used as a tool to assess the likely impact or effect of a particulardesign. This is in conjunction with field observations, experimentation andmonitoring. The tools provide what is essentially a platform for the organisation of allthe information associated with the drilling and blasting process and associatedresults.

One of the key advantages of the system is that it uses relational databases as the datastorage facility and Microsoft Access for the database engine. Being MicrosoftWindows based, it requires little training for those familiar with windowsapplications. In addition to the applications described earlier, the system can be aninvaluable training tool for undergraduates, operators and all personnel involved inunderground drilling and blasting activities.

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ACKNOWLEDGMENTS

The authors would like to thank the JKMRC-AMIRA BART project sponsors andAnglogold Brazil for supporting the further development of the software.

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