News From EFEE Lisbon Conf Papers

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News from the

6th

EFEE WorldConference onBlasting

Lisbon 2011

1R. Holmberg Lima Nov 2011

European Federation ofExplosives Engineers



An overview


ExhibitionSponsors 12 (3 Gold, 9 Silver)

Booths Sold 41

RegistrationsConference Registrations 161

Corporate Registrations 14

EFEE Members 50

225



329 attendeesrepresenting 51 countries


● Australia 9

● Austria 6

● Belgium 4

● Bosnia 3

● Brazil 2

● Bulgaria 1

● Canada 6

● Chile 7● China 2

● Columbia 1

● Croatia 1

● Czech Republic 5

● Denmark 3

● Egypt 3

● Finland 26

● France 11

● Georgia 1

● Germany 15

● Greece 4

● Greenland 1

● Hong Kong 1

● Iceland 1

● India 4

● Israel 2

● Italy 1

● Japan 1

● Jordon 2● Korea 2

● Lithuania 1

● Malaysia 2

● Malta 1

● Morocco 4

● Netherlands 1

● Nigeria 1

● Norway 3

● Peru 1

● Poland 25

● Portugal 21

● Russia 32

● Saudi Arabia 1

● Slovakia 1

● Slovenia 2

● South Africa 22

● Spain 6

● Sweden 21

● Switzerland 14● Turkey 11

● UK 21

● Ukraine 9

● UAE 1

● USA 13



Student awards A Farinha

Explosive densification

of nanometric powders V Zhulikov

Mathematical modeland software for the

design of blasting

R. Holmberg Lima Nov 2011 4



A probabilistic analysis of vibration based on measured dataand charge weight scaling. (1)

D. P. Blair TNL Consultants, Carine, West Australia

Charge weight scaling and waveformsuperposition are the two methodsgenerally used to estimate the peak levelof vibration for any planned blast.

A detailed review shows that simplecharge weight scaling has distinctadvantages over waveform superpositionwhen considering vibration probabilityanalysis.

His paper shows how the charge weight

scaling method can be upgraded topredict the probability of exceeding aprescribed vibration limit for any plannedblast.

His method requires only a databaseof measured peak levels andcorresponding scaled distances, ithas no adjustable parameters and

can be coded as a simple recipe forfast execution in standardspreadsheets.




A probabilistic analysis of vibration based on measured data and chargeweight scaling. (2)

Blair - pros and cons Super position

In the simplest form of this technique,each blasthole is considered to emit acharacteristic (seed) waveform that is

time-delayed according to the blastdelay sequence. The vibrationwaveform due to the complete blast isthen mimicked as a summed anddelayed version of all waveforms dueto all blastholes.

If a relevant database of peak levels isavailable, Blair states that his probabilisticanalysis will be more realistic andsignificantly less expensive than anyequivalent probabilistic analysis based onMonte Carlo waveform superposition.

Blair notes that the Monte Carlosuperposition model, perhaps moreso than most models, is subject tothe GIGO principle (garbage in –

garbage out). The implementation of such a model

requires significant experience toobtain appropriate seed waveforms,to determine the variability of theirscaling relationship and to set themodel parameters for time-dependent ground damage andscreening.




A probabilistic analysis of vibration based onmeasured data and charge weight scaling. (3)

Blair – Simple recipe Set the distance, d, and charge weight,

W, for the planned blast in any consistentmanner, then calculate the scaleddistance, S=d/W0.5

Log-linearise the data set as perlog (V P)=log(a)-b log(S)then do a standard linear regressionanalysis to determine the constants,log(a ) and b .

Calculate or estimate the standard

deviation, σ Set the desired exceedence criterion, V β

(mm/s). This value will typically be 5mm/s or 10 mm/s for compliancemonitoring, 25 mm/s for structuralvibrations and significantly higher for blastdamage.

Knowing log(a ), b , log(d/W0.5) , σ and Vβ

calculate zβ by

the probability of exceeding a prescribedvibration limit, Vβ, at any specified scaleddistance, d/W0.5 can thus be calculated.

If zβ ≤ 0 then use the following equation tocalculate the probability, P (V> V β) , thatthe planned blast will exceed the prescribedlevel, Vβ .

If zβ < 0 then use the following equation tocalculate P (V> V β) .




A probabilistic analysis of vibration based on measured data and chargeweight scaling. (4)

Blair - Words of wisdom

It is always unwise to extrapolatebeyond the bounds of the measureddata. Thus if the scaled distance of

the planned blast lies outside therange of scaled distances stored inthe vibration database, then theresults of the probabilistic analysisshould be viewed with caution.

This caution regarding extrapolation

also applies to any waveformsuperposition model, which relies onthe experimentally determinedscaling law for individual (seed)blastholes.


Example



The Future of the Detonator (1) A.Ivanov & V.Molochkova

ISKRA Novosibirsk Mechanical Plant, JSC., Novosibirsk, RUSSIA

The authors represent anexplosive manufacturer inRussia. They have developed ahybrid electronic detonator.


1. Plain instantaneous detonator cap2. Electronic delay module3. Magnetic pulse generator4. Bush/plug

5. Shock tube6. Label

Magnetic pulse generator

Standard 4 diode bridge schemecharging the capacitors. Extra smalldiodes with low current leakageunder the maximum voltage of 50 Vwere used.

The electronic module and themicroprocessor are powered by thelow voltage generated by thecapacitors charged in the seriescircuit.





The circuit has got temperaturecompensation function to avoidambient temperature impact on thefiring precision.

Thin film fuse head has been designedto shorten the time before firing.

Delay time with the tolerance of 1(one) ms is programmed at theproduction stage with the actual shocktube length taken into account.

ID-number can be assigned only onceduring testing or calibration, withoutthe possibility to alter it later on.


The Electronic Shock Tube BasedDetonator was designed for theapplication in the ambienttemperature range of -50 to +50 ºC

with the delays series of 1 to 3 000ms.






Protection from electromagnetic waves by the metallic case

Resistance to static electricity (the discharge of 20010 pF capacitor charged to101 kV)

Performance under the temperature of 805 ºС when exposed within 12 hours;

no premature detonation at exposure to the temperature of up to 1205 ºС within 1 hour.

Water resistance and operation performance when exposed: a) to waterpressure of 20 N/cm2 with РН from 4 to 9 or diesel fuel pressure within 14days; b) to the pressure of 1 N/cm2 on the free extremity of the shock tubewithin 48 hours

Resistance to the impact of a flat steel striker, falling at an angel of 30º with theenergy of 500 J both on the detonator cap and the shock tube

Resistant to static tension (minimum 80 N) applied to the joint of the shock tubeand the detonator cap

No premature detonation following 10 minutes shaking or 60 impacts of a fallingload from the height of 150 mm.






Table 4. Hybrid vs Conventional. Comparative Chart

Delay Timing Accuracy Electronic delay variation of ±0.2 ms vs conventional ±10% in

pyrotechnic delay Flexibility Any electronic delay, incremental of 1 ms vs limited delay timing

scenarios available by pyrotechnic composition combustion

Predictability Well designed blast pattern and total control during all steps provide for

100 % predictable behavior of the detonator Improved Fragmentation Visually evident and confirmed fragmentation improvement and size

uniformity, with less fly rock, due to appropriate blast energy

distribution Combinability Variety of blasting patterns (*) vs limited conventional options Reduced Vibration Minimized adverse vibrations due to proper explosive energy

distribution within a well designed blast hole plan

“Perfect accuracy in delay timing enables altering conventional drilling pattern. That is, increasing the distance between the holes in a row, the distance between the rows of hole, and therefore,decreasing the number of blast-holes to be drilled and filled with explosives. The efficient utilizationand distribution of the explosive energy loaded into the blast hole implies a higher powder factor,i.e. more cubic meter of waste material blasted per kg of explosives used. Thus, with better andprecise delay timings the explosive cost per blast block is reduced by 10 to 35 percent in massblasts.”

Price was not given!



The Importance of Sonicity in Blasting (1) H.P. Rossmanith1 & B. Müller2 1 Institute of Mechanics & Mechatronics, Vienna University of Technology, Austria 2 Movement & Blasting Consulting, Leipzig, Germany .


The paper deals with advanced blasting technology based on classical wavepropagation theory and fracture mechanics.

The authors show that the Mach number, i.e. the ratio between the velocity ofdetonation and the wave propagation speed controls the efficiency of a blast.

Numerous practical works support the new theoretical concepts.




For a homogeneous and isotropic rockmass there are basically three differentmodes of sonicity :

Supersonic detonation : cD > cP > cS

two conical Mach fronts MP and MS form. Transsonic detonation : cP > cD > cS

only one Mach front MS forms.

Subsonic detonation : cP > cS > cD ;no Mach cone.





The authors claim;

In the past, the selection of theexplosive as well as the initiationand delay times and intervals for a

blast was based on experience andtrial and error.

The introduction of electronicdetonators caused a change ofparadigm towards shorter delaytimes.

The introduction of the principle ofsonicity will lead to a second changeof paradigm in blasting – theselection of the type explosivebased on issues of wavepropagation and detonation speed.


The most important conclusion thatcan be drawn from the sonicityclassification is the realisation thatthe mode of detonation of an

explosive is not a priori pre-determined. In other words: Thesame explosive can detonatesupersonically, transsonically andsubsonically, the mode dependingon the wave propagation speeds ofthe rock mass in relation to the

detonation speed of the explosive.This is called the principle of sonicity or principle of relativity ofdetonation .









The authors claim;

In the light of sonicity thirty years of blasting experience boil down to thefollowing statements:

Subsonic conditions (velocity of detonation is smaller than the wave propagationspeeds) lead to inferior fracture network development, i.e. to poorer fragmentationin the nearfield of the charge (blasthole) and to increased vibrations.

Transsonic conditions (velocity of detonation lies between the P-wave velocityand the shear wave velocity or is approcximately equal to either one) yield

acceptable fracture network formation and fragmentation in the nearfield of thecharge und generate fair to small vibrations.

Supersonic conditions (velocity of detonation is higher than the P-wave speed)guarantee optimal, even excellent fracture network development and are associatedwith the least vibrations.



BLAST OPTIMISATION WITH IMPEDANCE MATCHING USING SURFACE-WAVE TOMOGRAPHY AT AN OPENCAST COAL MINE (1) M. Ramulu1 , A. K.Jha2 and A.Sinha1 1 Central Institute of Mining & Fuel Research, Nagpur-440006, India,2 Central Mine Planning and Design Ltd. HQ, Ranchi.

.


Multichannel analysis of surface waves (MASW) was used fordetermination of in-situ compressional wave velocity of rock mass. Thistechnique was applied at sandstone benches of a coal mine for rock masscharacterization and blast optimization by impedance matching ofexplosives

Field experiments were conducted on seismic profiling to characterizesandstone rock mass on the basis of P-wave velocity (Vp) measurements.

This data was used for the selection of explosive with desired velocity of

detonation and density, so as to match the impedance and of rock mass. The paper stresses the need for conducting impedance matching

exercise for all the blast sites for blast optimization andproductivity improvement.




.


It is often observed that practising engineers indiscriminately use explosivecharges to improve fragmentation with scant regard to rock formationsand explosive properties. This may not be in the best interest of theoverall mine productivity.

It calls for a study on proper selection of explosive for various rockproperties. The best matching for optimum shock wave transmission to therock occurs when the detonation impedance of explosive is equal to theimpedance of the rock material (Atchison, 1964). Impedance is theproduct of compressional wave velocity and density of the material.




.


The instrument called Geode(Geometrics controllers Inc., USA) wasused for acquiring the data for surfacewave analysis using Multi Channel

Analysis of Surface Waves (MASW)technique.

The sensors used were of 14 Hzfrequency and 24 in number.

The sensors were spread at 1m spacing

and the seismic source was at 5mdistance in all the experiments.

A sludge hammer of 10 lb weight wasused as seismic source.

Various components of the MASW system




.


The field experiments on seismic profiling and impedance matching were conductedat KOCP of Western Coalfield Ltd (WCL), Coal India Ltd.

The authors conducted a seismic profiling survey to characterize sandstone rockmass on the basis of P-wave velocity measurements (Vp) . The survey was

conducted at the surface of sandstone rock mass at three locations of the minecovering hard, soft and medium rock mass

The P-wave velocities of individual layers were varying from 240m/s to 2200m/sfrom top to bottom. The poor Vp at the top might be because of fractures generateddue to the weathering of the rock mass.

468

478

488

498

508

E l e v a t i o n

(m)

-8 2 12 22 32 42 52

(m)Distance

(m/s)

300

511

722

933

1144

1356

1567

1778

1989

2199

Scale = 1 / 3

500

1500

2200

518

528

538

548

558

E l e v a t i o n

(m)

-16 -6 4 14 24 34 44(m)Distance

(m/s)

300

600

900

1200

1500

1800

2100

2400

2700

2999

Scale = 1 / 3

300

1000

2000




.


The prevailing blasting practice at KOCP mine was carried out with cartridgedexplosives of fixed velocity of detonation (VOD) for all the benches, irrespective ofvarious rock properties.

The blast results like fragmentation, throw and peak particle velocity of vibration

were monitored using high resolution video camera and seismographs.Fragmentation size distribution analysis was carried out by image analysis softwarecalled FRAGALYST.




.


Blast Optimization by impedance matching

The best matching for optimum shock wave transmission to the rock occurs whenthe detonation impedance of explosive is equal to the impedance of the rockmaterial.

According to the theory of impedance matching, the explosive impedance shouldbe as nearer to the rock impedance as possible to couple the explosive inducedstress waves through the rock mass. The impedance matching expression is givenbelow (Persson and Holmberg, 1994).

eCd =Zr rCp

where,

e = explosive density, Cd = VOD of explosive, r = rock density, Cp= P-wavevelocity and Zr = impedance ratio




.

The improvements in blast performance due to impedance matching weresubstantial in terms of blast fragmentation and vibration as well as damagecontrol.





.

Authors Conclusions

The improvements in blast performance due to impedance matching were

substantial in terms of blast fragmentation and vibration as well as damagecontrol.

The blast results shown in this study, clearly indicate that the selection ofproper explosives with impedance matching to the rock impedance result inimproving the blast fragmentation, reducing the throw and reducing of blastvibrations.

Therefore, impedance matching should be given adequate importance whileselection of explosive for improving blasting productivity and safety.




ASYMMETRIC PROPAGATION OF AIRBLAST FROM BENCH BLASTING (1) P. Segarra1, L.M. López1, J.A. Sanchidrián1, J.F. Domingo2.1 Universidad Politécnica de Madrid -ETSI Minas, Madrid, Spain2

MAXAM Europe, Madrid, Spain


Propagation of airblast from quarry blasting.

Peak overpressure is calculated as a function of blasting parameters (explosive massper delay and velocity at which the detonation sequence proceeds along the bench)and polar coordinates of the point of interest (distance to the blast and azimuth with

respect to the free face of the blast). The model is in the form of the product of a classical scaled distance attenuation

law times a directional correction factor. The latter considers the influence of thebench face, and attenuates overpressure at the top level and amplifies it at thebottom.

The model has been fitted to an empirical data set composed by 134 airblast

records monitored in 47 blasts at two quarries. The measurements were made atdistances to the blast less than 450 m.



Vibration velocities resulting from the use of explosivesin different rock masses. (1)F. Tavares de Melo

MaxamPor, S.A., Lisboa Portugal


The work presents a study of the vibration particle velocity resulting from the use ofexplosives in different rock masses granite, limestone and quartzite.

There has been monitoring phase and data collection phase in each situation.

Three different laws of propagation of vibration velocity;

Johnson (1971), Langefors & Kihlström (1978)

Chapot (1981)

were used to calculate their site specific constants by statistical method of multiplelinear regressions.

After obtaining the constants, studies were made to predict the particle velocitieswhen applying the same explosive charges in the rounds.

The authors say the aim of this study was to identify which of the formulas is thebest for each type of mass studied, using real data from several blasts done indifferent types of geological mass (quarries and construction sites).



Vibration velocities resulting from the use of explosivesin different rock masses. (2)F. Tavares de Melo

MaxamPor, S.A., Lisboa Portugal


Johnson

Langefors&Kihlström

Chapot



Vibration velocities resulting from the use of explosives indifferent rock masses. (3)F. Tavares de MeloMaxamPor, S.A., Lisboa Portugal

Comparison weremade for the threevarious blast sites/rock

masses. Author found Johnson

giving the best linearregression fit.




MATHEMATICAL MODEL AND SOFTWARE FOR THE DESIGN OFBLASTING (1) V.V. Zhulikov

MSMU, Moscow, Russia

Student award. Two students were invited to present their papers.

Computer program for the calculation of blasting parameters in open-castmines.

The “Bench blasting” program is based on a mathematic model of rockblasting by charges in the holes and on the method of calculating the blastingparameters. Both model and method have been developed at the Moscowstate mining university by the blasting craft department.

The model of blasting-rock is founded on particularily the Weibullfragmentation distribution, on deformation zones in the bench, and onexperimentally confirmed dependence of muckpile pieces on charge

parameters and physical rock properties. Most equations are from, Cunningham, Holmberg, Persson, Kuz-Ram, Weibul,

Konya, Kou and Rustan




Opportunities to optimise project economics throughapplication of digital drill and blast technologies (1)Per Eriksson, Tunnel Superintendent, Northern Rock, SwedenGunnar Nord, Senior Adviser, Atlas Copco AB, Sweden

Dave Kay, Technology Applications, Orica Mining Services, Australia

The NL35 contract wasawarded to the joint Venture Hochtief-OdenTunnelling that required

the underground drill andblast removal ofapproximately 420,000 m3 of rock. Oden wasresponsible for the rockexcavation of tunnelcross-sections varying

from 15 to 320 m2 thatwere completed 2 monthsahead of schedule.

Fixed cost is 550,000 € perday so it is important toget the rock out asap.






One of the tunnels (no. 512) was drivenfor 250 metres parallel to a vibration-sensitive facility only 10 m away where amaximum vibration level of 100 mm/s

was permitted. The cross-sectional area in the section

varied between 110 and 125 m2

250 holes in tunnel face

Max instantaneous charge varied from1-6 kg.

Speed is money!

CONSIDERATIONS

Segmented blasts as pilot and stross Failed because temporary rock support was

required between blasts

face off-set delays (blocking) wasfound to be effective however, due to the inherent scatter with

pyrotechnic delay detonators, it could notguarantee true single hole firing.

reduce charge weight and henceadvance per round adverse impact on the project schedule

full face firing using electronicinitiation systems was choosen






Experience with full face electronicinitiation

The i-kon™ VS system was used withthe most obvious benefit being that any

delay time could be programmed to thedetonators up to a total time of 8000milliseconds. This allowed the flexibilityto apply individual firing time to eachshot hole.

It was possible to identify each shot hole

firing and gauge their position in theblast and their individual vibration levelsand t was possible to perform adiagnosis of the design and instigatechanges to the shot hole design,charging and initiation plans to ensuremaximum advance for each firing.

Adjustments to the drill plan could beeasily achieved through computeraided design being sent to the AtlasCopco drill jumbo to allow accurate

shot hole placement using the drillnavigation system.






Experience with full face electronicinitiation

The i-kon™ VS system was used withthe most obvious benefit being that any

delay time could be programmed to thedetonators up to a total time of 8000milliseconds. This allowed the flexibilityto apply individual firing time to eachshot hole.

It was possible to identify each shot hole

firing and gauge their position in theblast and their individual vibration levelsand t was possible to perform adiagnosis of the design and instigatechanges to the shot hole design,charging and initiation plans to ensuremaximum advance for each firing.

Adjustments to the drill plan could beeasily achieved through computeraided design being sent to the AtlasCopco drill jumbo to allow accurate

shot hole placement using the drillnavigation system.

NCVIB web-based system.

A network of vibration sensors wereplaced along the critical infrastructureto provide compliance measurement.

The vibration results from blasts wereavailable to all project stakeholderswithin minutes of firing and allowedfor rapid assessment of results andplanning for the next round.






Drill navigation systems

The digitised guiding systems on booms and feeds for the Atlas CopcoBoomer E2 C drill rig have drastically improved the accuracy of the locationof the blast holes.

The position of the rig itself can be established with accuracy of 1 cmwhilst traditional navigation gives a less accurate position and normally thedeviation is within some 7 cm.

One application foreseen in the near future is transfer of information of theactual location of the blast holes to the charging unit for adjustment of thecharging or drilling extra holes.






Measure While Drilling (MWD isanother digital platform where up toeight parameters are recorded:Penetration rate, Percussive pressure,Feed pressure, Rotation pressure,Rotation speed, Damper pressure,Flushing water pressure, Flushingwater flow.

From these recordings anomalies inthe rock-mass can be traced. These

anomalies normally indicate variationsin the rock quality. The anomalies mayindicate that the rock support or thepre-grouting procedure has to bealtered but also that the chargingpattern should be changed.






In the NL35 case study a number of digital technologies were used to optimisesuccessive blasts and maximise each opportunity. This strategy led to firing the leastpossible number of blasts to complete the rock excavation phase.

Integration -For example, Atlas Copco Tunnel Manager software can communicate withOrica SHOTPlus software using the IREDES protocol. This allows for an improvedcapability to manage the drill and blasting processes and deployment of electronicblasting systems. Orica tunnel software can make use of the waveforms from the NCVIBsystem to perform blast diagnosis by matching with the delay sequence applied toelectronic detonators. Atlas Copco drill navigation systems can then deliver the changesin design to optimise the next round.

The future possibilities are almost limitless provided that the data collection andreporting systems can work together to provide useful information to allow decisionmaking for the next production cycle.

Beyond this, integration with survey scanning techniques and MWD data has many morepossibilities to optimise the drilling and blasting processes.






Drill and Blast tunnelling may be viewed as a mature technology butstill represents the majority of global tunnel advance due to itsinherent flexibility and low capital set-up.

The authors hopes that this paper represents that Drill and Blasttunnelling is still on the technological edge and has plenty moreopportunities to explore.

The use of digital technologies may not provide the revolutionaryimpact of pneumatic drills or dynamite high explosive, but rather the

combination effect to take the industry into a new dimension.




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News From EFEE Lisbon Conf Papers