A Lecture Holmberg&Persson Math Model
-
Upload
vh-paredes-canto -
Category
Documents
-
view
231 -
download
0
Transcript of A Lecture Holmberg&Persson Math Model
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 1/77
Mathematical Model for Near
Field Rock Damage Control(Holmberg&Persson)
1R. Holmberg Lima 2011-Nov
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 2/77
BackgroundProject ”Cautious Blastingtowards Open Pit Slopes”
Virgin rock, first bench
Aitik Copper Mine – a lowgrad, 0.4%Cu, mine inNorthern SwedenPegmatites and manytypes of gneiss withzones of feldspar andepidote parallel to thefoot wallBoliden Mineral, NitroNobel, SveDeFo
R. Holmberg Lima 2011-Nov 2
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 3/77
Aitik, Sweden
3R. Holmberg Lima 2011-Nov
P,A&H rock mechanicslope stability analysis
indicatedγ ~57 ° β i ~ 62 ° a ~10 m
a berm widthb catch benchα bench angleβ i intermediate slope anglesγ total slope angle
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 4/77
AITIK
It was common that back breakreached 8 m which implied that the totalslope angle just could be 40 ° instead ofestimated 57 ° if extreme cautiousblasting was performed.Millions could be saved for each degreethe pit slope angle was increased.
A change of the blasting procedure wasneeded.
An understanding of how blastingdamage is defined and how it is causedis needed!
R. Holmberg Lima 2011-Nov 4
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 5/77
Alternative designs
If the last bench has a benchheight of 15 m the berm/catchbench will be 9 m if the totaloverall slope angle is 57 °.Local bench failures, back breaketc will make it impossible toachieve.
A proposal was to finalise with a30 m bench in order to achieve
broader berms.Heigh benches are not easy totrim!
R. Holmberg Lima 2011-Nov 5
Stock blast
Cautiousblasting
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 6/77
Tests at footwall
6R. Holmberg Lima 2011-Nov
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 7/777R. Holmberg Lima 2011-Nov
Tests at footwall
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 8/77
Local planar failures
8R. Holmberg Lima 2011-Nov
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 9/77
First approach
R. Holmberg Lima 2011-Nov 9
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 10/77
2nd approach
v; particle velocity mm/sQ; Charge weight kgR; Distance mk, α and β
R. Holmberg Lima 2011-Nov 10
v=k Qα /R β
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 11/77
Mathematical model
R i 2= R 02 + (R 0 tanΦ) 2
Q i = dx L (L= linear charge conc. kg/m)q = (v/k) 1/α = Q/R β/α
Each part Q i of the charge Q contributes to thevibration intensity defined as w= v 1/α with
w i = (k Q iα/R iβ)1/α
Integration along the charge height H gives
R. Holmberg Lima 2011-Nov 11
v=k Q α/R β
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 12/77
Curves of particle velocity,v versus distance, R
R. Holmberg Lima 2011-Nov 12
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 13/77
Aitik Copper Mine – Round
#213Bench Height 13-14 mNumber of holes 96Hole diameter 250 mm
Hole Depth 16 mSpacing 10 mBurden 8 mUnloaded hole length 3-3.5 mExplosives TNT SlurryLinear Charge concentration 75 kg/mInitiation 2 primers; one at the bottom part and one 2 m abovebottom. Nonel.
R. Holmberg Lima 2011-Nov 13
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 14/77
Accelerometer positions
R. Holmberg Lima 2011-Nov 14
Initiation
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 15/77
15R. Holmberg Lima 2011-Nov
First measured values
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 16/77
Accelerometers
R. Holmberg Lima 2011-Nov 16
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 17/77
Back break
R. Holmberg Lima 2011-Nov 17
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 18/77
18R. Holmberg Lima 2011-Nov
Damage zone?
Damage zone
Distance frombench face
Degree ofdamage
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 19/77
Diamond drilling
R. Holmberg Lima 2011-Nov 19
1 and 2 – Right angle todominating fractures3 was drilled dipping 50 ° to crossthe foliation
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 20/77
Cracks
R. Holmberg Lima 2011-Nov 20
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 21/77
RQDRQD=Sum of allcore pieces
larger than 10cm divided bythe bore holelength
5 m length wasused
R. Holmberg Lima 2011-Nov 21
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 22/77
Results At 90% probability, damage(increase of crack frequency)ceases 18.6-44.9 m along thecore length.The diamond drill holes aredrilled at an angle of 45degrees to the face.I.e. at 90% probability,damage (increase of crackfrequency) ceases 13.2-31.9m behind the last row.
At a distance of 22.6 mbehind the round theprobability is 50% fordamage.
Damage Zone ~23 m. Implies apeak particle velocity of 800mm/s.
R. Holmberg Lima 2011-Nov 22
% increase of crack frequency
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 23/77
Damage zoneThe typical damage in fissured rock isan irreversible separation of the two
fissure surfaces from each other,resulting in a decrease in shear strengthof the fissure. This is accompanied by aslight swelling of the rock mass
effected.
R. Holmberg Lima 2011-Nov 23
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 24/77
Swelling of rock mass behind
blasts
R. Holmberg Lima 2011-Nov 24
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 25/77
Critical vibration velocity range for
damage in different rock mass typesRock /jointclass
Criticalvibrationvelocity mm/s
Hard rock –
Strong joints>1000
Medium hardrock - no weak
joints
800-700
Soft rock – weak joints
<400
Granite may be expected to fail indynamic tension at ~30MPacorresponding to a strain of ~1% or aparticle velocity of more than 1000
mm/s.Normal fissured rock will show tensiledamage in the joints at low stress levels~700mm/sIn soft, sedimentary rock with relativelyweak joints damage may occur atvelocities lower than 400 mm/s.
R. Holmberg Lima 2011-Nov 25
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 26/77
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 27/77
Damage zone 0,6 mNot affordable for
low grade ores!
R. Holmberg Lima 2011-Nov 27
Low damage zone but expensive
Stock blastCautiousblasting
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 28/77
Realistic design!?Discussions led to a potentialdesign.Max damage zone = 10 m.
2 rows cautious blasting.Last row reduced to 35% of afully loaded 250 mm hole.This is the same as a fullyloaded 171 mm hole.
Attractive for the mine asdecoupled charges in 250 mmholes not needed.Further investigations to confirm171 mm holes damage zone.
R. Holmberg Lima 2011-Nov 28
Stock blast10 m damagezone
Reduced charge conc in the last2 rows
Cautiousblasting
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 29/77
Kidd Creek
R. Holmberg Lima 2011-Nov 29
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 30/77
Kidd Creek
R. Holmberg Lima 2011-Nov 30
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 31/77
Brenda MineOverall slope angle 45 ° exclrampsBackbreak Prod row; 10 m
Pretrim; Reduced subdrillingand chargeTrim; 70 kg ANFO + 2waxed cardboard tubes with70 kg ANFO each
Deck charging; Testedpreviously but gave not thesame results as decoupledcharges. And moreexpensive.
R. Holmberg Lima 2011-Nov 31
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 32/77
Continuation to verify the
Curves
32R. Holmberg Lima 2011-Nov
Cautious blastingwith 171 mm hole
diameter was testedat the Aitik mine.Hole inclination 70° Observations
DisplacementPeak particlevelocities
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 33/77
Accelerometer positions
Smoothblasting Φ=171mmLinear chargeconcentration32 kg/mTNT slurry
R. Holmberg Lima 2011-Nov 33
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 34/77
Results - PPV
R. Holmberg Lima 2011-Nov 34
Hole # Distance (m) a (g) v (mm/s)B 8,5 1031,0 1442,0C 13,9 303 562
D 26,9 29 283
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 35/77
Results - Displacement. Most
severe at surface.
R. Holmberg Lima 2011-Nov 35
Extenso-meter
Distance toblast hole (m)
Displace-ment (mm)
E1 8,5 37,8E2 14,1 14,4E3 27,3 2,6
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 36/77
Leveäniemi Iron Ore MineTest site Sector 1Aand 4B
Foliation dips 55° Strikes parallell tothe pit limit
Typical failures:Plane shear failuresalong the foliation
R. Holmberg Lima 2011-Nov 36
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 37/77
Sector 1A
R. Holmberg Lima 2011-Nov 37
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 38/77
Data Biotite schist
Tensile strength 17.8 MPaUniaxial compressive strength 102.7 MpaDensity 2.74 g/cm 3
Shear strength 42.2 kPa
Elastic Modulus of 39.9 GPaPoisson´s ratio 0.18
R. Holmberg Lima 2011-Nov 38
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 39/77
Typical production round #81
TNT-slurry 1.5 g/ccCord ,100 ms between rows
V1-V3 denotes PPV sensors
R. Holmberg Lima 2011-Nov 39
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 40/77
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 41/77
Back break
R. Holmberg Lima 2011-Nov 41
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 42/77
Measurements V1-V3 PPV sensorsE1-E3 Extensometers
S1-S10 Holes forseismic measurementsP3 & P4 Core drilling –pre and post blast
R. Holmberg Lima 2011-Nov 42
Last row ofround #81
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 43/77
Extensometers8, 12 and 16 m fromblast
D=22 mm iron barsgrouted at thebottom of the holes
R. Holmberg Lima 2011-Nov 43
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 44/77
Displacements
R. Holmberg Lima 2011-Nov 44
Relativedisplacement Vertical
displacement
Distance fromlast row (m)
Distance fromlast row (m)
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 45/77
Horisontal displacement
Round #88 At surface the followinghorisontal displacements
were measured:
Distance fromlast row (m)
Horizsontaldisplacements(cm)
7.0 16.5-23.911.5 10.3-15.319.5 1.5-6.7
R. Holmberg Lima 2011-Nov 45
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 46/77
Estimated separation of
weakness planes
R. Holmberg Lima 2011-Nov 46
Distance from
last row (m)
Depth
(m)
Measuredverticaldisplacement
(mm)
Separationat 8 cracksper m
(mm) *8 0-6 151 3.26-16 74 0.9
12 0-6 131 2.76-16 49 0.6
16 0-6 57 1.26-16 18 0.2
*Crack frequency measured on the core after blasting
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 47/77
Core drillingCore drilling 20 m,inclined 45° fromsurface towards thebottom of the round.
R. Holmberg Lima 2011-Nov 47
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 48/77
RQDCore drilling 45° fromsurface towards thebottom of the round.RQD is decreased alongwhole core lengthSurface – heavilyfractured from earlierblasting
R. Holmberg Lima 2011-Nov 48
Pre-blastPost-blast
Distance from surface
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 49/77
Point Load Index Test
Strength higher after blast!Possible explanation -The boiotit schist has a number of
potential weakness planes. Each ofthem with an unique strength.Blasting introduces dynamic loadsand several low strength weaknessplanes will be fractured. The coreexamined after the blast willtherefore contain more fractures.Core pieces selected for the PointLoad Index Test will obviously notcontain the low strength weaknessplanes and consequently a higheraverage of the strength will beachieved.
R. Holmberg Lima 2011-Nov 49
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 50/77
Laboratory experimentsIntact rock 12 MPaInvestigate shear strength of joints after theyopened up.Equipment; Two steel plates parallell to eachother, separated 1 cm.Plates; Three throughgoing holes where threerock core samples with diameter 30 mm can bemounted.’ Structures in cores mounted parallell to theplates.Movements increase the aperture along the
fractured weakness planes. After a predetermined temporary aperture , thesurfaces are repositioned into contact and theapparatus is ready for shearing.The equipment could also provide a remainingaperture of the joints before shearing started-
R. Holmberg Lima 2011-Nov 50
• Weakness planes given a temporary apertureof 0.3 mm still had intact rock bridges
covering 7% of the area of the weaknessplane.• The remaining aperture of more than 0.4mm shows that the peak angle of friction isclose to the calculated basic angle of friction.
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 51/77
Seismic measurements
At 5 m depth and 21 m from last row the rock masscontinuity was disturbed.Seismic signals showed lower frequencies and velocities.
R. Holmberg Lima 2011-Nov 51
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 52/77
Test d=102 mm
R. Holmberg Lima 2011-Nov 52
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 53/77
Round #99
R. Holmberg Lima 2011-Nov 53
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 54/77
PPV for Round #81 and #99
R. Holmberg Lima 2011-Nov 54
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 55/77
Avoid cord VOD cord =7000m/s
VOD TNT Slurry =4500 m/sI.e. Detonation isoccuring at sametime in 3-4 holesdepending on thewave velocity in therock.
R. Holmberg Lima 2011-Nov 55
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 56/77
Leveäniemi -Summary
R. Holmberg Lima 2011-Nov 56
Meaasurements Damage zone
Extensometers - vertical displacement ~20 mEDM - Horisontal displacement ~22.5 mCrack frequency . Pre- and Post-blast cores >20 mSeismic >21 mPPV (v=750 mm/s) ~23 mShear strength tests on cores with simulated blast damages ~20 m
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 57/77
Proposed design
R. Holmberg Lima 2011-Nov 57
Total slope angle 42 ° Foliation 55° Berm 6.2 m
Final wall; Sector 1A and 4B
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 58/77
Inclined holes
R. Holmberg Lima 2011-Nov 58
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 59/77
Vertical holes
R. Holmberg Lima 2011-Nov 59
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 60/77
Final wall.
R. Holmberg Lima 2011-Nov 60
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 61/77
Final wall
R. Holmberg Lima 2011-Nov 61
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 62/77
Sublevel caving
R. Holmberg Lima 2011-Nov 62
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 63/77
Tunnelling
R. Holmberg Lima 2011-Nov 63
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 64/77
Tunnelling
R. Holmberg Lima 2011-Nov 64
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 65/77
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 66/77
(SveBeFo) Continued tests 1990-2000
R. Holmberg Lima 2011-Nov 66
Vånga Smooth Blasting Tests1. Started in 1991 and continue in direct co-operation withDyno Nobel & Swedish National Road Authority.2. Tests made in 2-4,5 m granite benches, blasting singleholes and groups of holes.3. Main test factors have been
- the blast hole diameter, d= 24-64 mm
- the decoupling ratio or charge size- the explosive type- burden and spacing- initiation delay between adjacent holes.
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 67/77
(SveBeFo) Continued tests 1990-2000
R. Holmberg Lima 2011-Nov 67
4. Post-blast work includes- post-split excavation of intact blocks- cutting of blocks with diamond saw
- crack visualization with dye penetrant - crack lengthmeasurements.5. During the years more than 200 holes & 250 saw cuts havebeen blasted and inspected
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 68/77
(SveBeFo) Continued tests 1990-2000
R. Holmberg Lima 2011-Nov 68
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 69/77
(SveBeFo) Continued tests 1990-2000
R. Holmberg Lima 2011-Nov 69
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 70/77
(SveBeFo) Continued tests 1990-2000
After the blast, large blocks aredrilled and taken out with quarrymen ´s blasting techniques to avoiddisturbing the crack pattern
The blocks are split to size withwedges and cut horizontally in alarge diamond circular cut-off saw.
R. Holmberg Lima 2011-Nov 70
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 71/77
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 72/77
(SveBeFo) Continued tests 1990-2000
R. Holmberg Lima 2011-Nov 72
Explosive Density VOD Energy Fumes harge dia.Lin. Conc. Hole dia. CouplingKg/liter m/s m/s l/kg mm kg/m mm ratio
Gurit 1,00 2000 3,50 930 17,0 0,23 51 0,33Gurit 1,00 2000 3,50 930 22,0 0,40 64 0,34
Kimulux 42 1,15 4800 3,20 903 22,0 0,44 64 0,34Emulet 20 0,22 1850 2,35 1125 bulk 0,45 51 1,00Detonex 80 1,05 6500 5,95 780 10,6 0,08 51 -
Secti o n n o Date Exp l o si ve Ch arg e Ho l e In i ti atio n B*S Sec tio n sh o w sd i a. m m d i a. m m m effect o f:
5:2 jun-92 Gurit 17 51 pyrotechnic 0,8 - 0,5 ordinary initiation, reference6:3:1-6:3:3 maj-93 Gurit 17 51 EPD, instantan. 0,8 - 0,5 instantaneous intiation
H2:4-H3:4 aug-94 Gurit 17 51 EPD, At = 1 ms 0,5 1 0,5 zipper blastingJ2-J3 aug-94 Gurit 22 24 EPD, instantan. 1,0 - 0,8 less decoupling
E7:1 -E8:1 jun-94 Gurit 22 64 EPD, instantan. 0,8 - 0,8 larger S/BM6:2 apr-95 Kimulux 42 22 64 EPD, instantan. 1,0 - 0,8 highVOD, 4800 m/s
G14:1-G15:1 jun-94 Kimulux 42 22 64 EPD, instantan. 1,0 - 0,8 highVOD, 4800 m/s39:3 sep-94 Gurit 17 51 EPD, scattered 0,8 - 0,5 side hole
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 73/77
(SveBeFo) Continued tests 1990-2000
R. Holmberg Lima 2011-Nov 73
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 74/77
(SveBeFo) Continued tests 1990-2000With other factors kept constant: The resulting crack lengths decrease with a decreasing coupling ratio.Fully charged holes show a more complex crack pattern withinteracting cracks.
A higher VOD generates many short cracks around the bore hole.Crack lengths may increase with increasing burden and arc-shapedsubsurface cracks may appear when spacing is increased.
R. Holmberg Lima 2011-Nov 74
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 75/77
(SveBeFo) Continued tests 1990-2000The time delay of initiation is important;
zero delay gives the shortest crackscrack lengths increase with the delay
a delay as low as 1 ms give crack lengths more like singlehole blastseven a linear sequence of 1 ms delays is inferior toinstantaneous initiationtraditional smooth blasting thus gives unnecessarily longcracks.
R. Holmberg Lima 2011-Nov 75
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 76/77
(SveBeFo) Continued tests 1990-2000
SveBeFo has tested the influence ofthe burden and the spacingthe hole or charge sizethe decoupling ratiothe VODthe initiation delay time between holes
2003 Swebrec (Swedish Blasting Research Centre)
was formed and the researchers lead by Prof. FinnOuchterlony has continued to measure and refinethe Rock Damage Models.
R. Holmberg Lima 2011-Nov 76
8/12/2019 A Lecture Holmberg&Persson Math Model
http://slidepdf.com/reader/full/a-lecture-holmbergpersson-math-model 77/77