11/16/2013

1

TAC –Rock Tunnelling Workshop

Vancouver, BC

November 16, 2013

By: Gordon Revey

OVERVIEW OF TUNNEL AND SHAFT BLASTING TECHNOLOGY

SCOPE• Blasting versus Mechanical Methods

• Managing Risk

• Identifying and Controlling Blast Effects

• Case Histories Demonstrating Controlled Blasting Techniques

Drill - BlastDrill - Blast

MechanicalMechanical

EXCAVATION METHODS TO BLAST OR NOT TO BLAST?

Use of mechanical or blasting methods depends on:• Volume of material• Hardness and structure• Schedule• Cost

?

GFR

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2

RISKS OF “NO BLASTING”

114 Mpa (16,500 psi)

RQD =96

RISK MANAGEMENT

SAFE & EFFICIENT

BLASTING

Ov

ers

igh

t1

RISK INCREASES WHEN ANY OF THESE SUPPORTING MEASURES AND CONTINUITY

OF PURPOSE ARE WEAK

3

4

2P

requ

alification

De

sig

n

Sp

ec

ifica

tion

s

BLASTING PROCESS

The Blasting Process

Rock Characteristics

INFLUENCINGFACTORS

Explosive Properties

Design Variables

Fragmentation

RESULTS

Broken Rock Profile

Damage

COMPLEXBLAST

PHYSICS

PHYSICAL PROPERTIES

Stress = F/A (MPa or psi)

D

Force (F) F

A

No Load

After LoadArea (A)

1/2 w

d

Direct Strain = d/D Tangential Strain = w/W Poisson's ratio = w/d

W

Young's Modulus = F/{d/D} (GPa or psi)

1/2 w

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ROCK PROPERTIES

Static Static Rock Density Young's Compressive Tensile Type (g/cm3) Modulus Strength

Strength(GPa) (MPa) (MPa)

Basalt 2.4-2.9 35-60 50-300 6-30 Sandstone 2.2-2.7 10-40 40-150 2-15 Siltstone 2.0-2.8 10-15 40-130 2-12 Coal 1.2-1.5 2-8 4-40

MODERN EXPLOSIVE TECHNOLOGY

1DANGER DETO NATEUR

DANGEROUS DE TONATOR

LP

Dang

er -

Exp

l osif

s

Te

nir e

loi g

Dan

ger -

Exp

l osi

fs

T

eni r

n

Exp

los i

ves

- Da n

gero

usl d

ren

Expl

osi v

e s -

Dan

ger

Modern explosives are much safer than the old "Dynamite and fuses" seen in Hollywood Movies

The effects of controlled construction blasts look nothing like the gasoline explosions used to create spectacular movie scenes

Commercial blasts are very controlled and carefully regulated

EXPLOSIVES

Molecular and Composites

EMULSIONS

Oxidizer Salts in Aqueous Phase,Oxidizer Salts in Aqueous Phase,Surrounded by Oil-Phase MatrixSurrounded by Oil-Phase Matrix

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SENSITIVITY

0

300

600

900

1200

1500

1800

2100

2400

2700

Bu

llet V

eloc

ity N

eede

d To

Initi

ate

(ft/s

ec)

PROJECTILE IMPACT TEST

DYNAMITE

H.E. Emulsion

ANFO

H.E.Watergel DYNAMITE VERSUS EMULSION EXPLOSIVE GAP SENSITIVITY

Dynamite Propagation Gap =18 to 24 inches

2 to 3 in.Open Gap

Detonator

RECEPTOR

DYNAMITE

EMULSION

DONOR

Emulsion Fails to detonate throughcardboard separation

Zero Gapwith Cardboard

DONOR

DONOR

RECEPTOR

RECEPTOR

EMULSION

EXPLOSIVES HANDLING AND SECURITYThe Canada Explosives Act (R.S.C., 1985, c. E-17)Canada Department of Natural Resources

Blasting Explosives and Initiation Systems -Storage, Possession, Transportation, Destruction and Sale Rules, March 2008Guidelines for Bulk Explosive Facilities –Minimum Requirements, July 2010

Transport Canada Transportation of Dangerous Goods Regulations and Transportation of Dangerous Goods Act.

BLAST EFFECTS

Shock Front

ReactionZone

UnreactedExplosive

Tensile StressCracks

Gas ExpansionHeaving &Displacement

Shock & Heave EnergyCracking and RuptureVibration and Overpressure

RADIAL CRACKING

RadialCompressive Stress

Limited Blasthole Crushing--in hard rock

TangentialTensile Stress

Stress/StrainWave Front

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ROCK STRUCTUREBedding PlanesPartings & JointsCaves and Mud SeamsFaults

JOINT EFFECTS

JOINTING EFFECTS ON CRACK PROPOGATION

Minor Joints or fissures

Open Joint

Radial CracksPass Through

Cemented Joints

Cemented Joint

CrackFronts areStopped byOpen Joints

ENERGY LOSS

Gas Venting Though Open Joints

B locky F ragm entationand poor breakage

Blast gases venting through open joints (Lost heave energy)

PLASTIC DEFORMATION

Deformation in Soft / Porous Material

Explosive energy is Lostto the Rock's Internal friction

LimitedRadialCracks

Hole Expands (Plastic Deformation)

-Argillite-Wollastonite-Marble-Conglomerate

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TUNNEL BLASTING

Drill Jumbo

LaserBeam

RockBolts

Face

DRILLING

Tunnel FaceInvert

Crown

LaserBeam

Shotcrete

RockBolts

LOADING2

1

Tunnel Face

BLAST AND VENTILATE

Tunnel Face

Tunnel Face

SUPPORTING TUNNEL

Load Haul DumpUnit

SCALE & MUCK

Tunnel Face

TEMPORARY GROUNDSUPPORT

5

Tunnel Face

6

Muck

Shotcrete

Air & Water

Material Hopper

Scaling

Shotcrete

Muck

Scaling

GROUND SUPPORT

FINAL SUPPORT7

8

Bolter

Tunnel Face

Shotcrete

Concrete Pump Surveyor

Tunnel Face

LaserSpot

Alignment Laser

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TUNNEL ROUND ELEMENTS

Spacing

Lifters

Buffer Holes

RibHoles

Burden

Smoothwall orBack Holes

Knee Holes

Cut

DRILLING GEOMETRY

CutHoles

Lifters

Buffer Holes

RibHoles

Smoothwall Arch Holes

KneeHoles

Perimeter HoleSpacing (S)

Burden (B)

SpringLine

GradeLine Loaded

Cut Holes

Burn Cut Detail

Void(unloaded)Cut Holes

TUNNEL BLASTING

Perimeter Hole Look-out Angle(Just enough for drill room)

Over drillthe burncut

ExpectedBreak

Round Advance

Cut holes

B u ffe r H o le

P e rim e te r (b ac k ) H o le

K ne e H o le

Lifter H ole

Designed overexcavation tocreate room for Drilling

MinimumTunnelDimensions

CUT METHODS

Fan Cut Round

1 2 3 4 5

1 2 3 4 5

6

6

7

7

11 11 1212

8 7 7 8

109910

Timing Sequence

Z1

2

3

4

5

56

6

3 " Reamed Hole

12"

14"

16"

18"

SHIELDED BLASTHOLE BURN CUTFOR 1 3/4 to 2 inch JUMBO ROUNDS

3'

6"

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EXAMPLE TUNNEL ROUNDS

SPRINGLINE

6 6 77

11

1720' 8"

10' 4"

SmoothwallHoles

Buffer Holes

Buffer Holes

z

z112 2

3

4

4

3

5

5

5

5

6 6

7

7

7

7

88

8

9

99

9

9

1010

1010

1111 11

11

11

11

10

10

10

12

1212

1212

13

13

13

13

13

13

13

13

13

1313

1314

1414141414

1414

14

8810 1011

15 15 1515 15 16 1717 16

68

7

SmoothwallHoles

2.5'

2.5'

2.5'

2.5'2.5'

CONTROLLING OVERBREAK

0.50

0.50

0.50

0.50

00.25

0.751.0

00.25

0.75

00.25

0.7500.25

0.75STRESSLEVEL

Effect of hole size and decoupling on rock stress -- after Hunter

6"

Fully Coupled

Distance to observation point

36"

Fully Coupled2"

Deoupled in air

Deoupled in water

BoreholeWall

SMOOTHWALL BLASTING

Desired Perimeter of Excavation

SMOOTHWALL MECHANICS

Detonating light charges along the perimeter of an excavation with minimum time separation creates tensile stress that cleaves rock at the desired limits of the excavation.

Some overbreak caused by joints and other structure in rock may occur

Minor radiial cracks

CompressionalStress

TensileStress

TYPICAL CHARGES

Buffer Load

Blasthole Load

Smoothwall Load

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DRILL LOOKOUT LIFTER CHARGES HEAVE ROCK

Lifter CollarPipe

L if te r H o leL if te r H o le

LiftersKnee Holes

OVERBREAK CAUSES CHARGE SEPARATION

Ground Shift Cut-off and Charge Separation in Jointed Rock MassCaused by:

OverloadingPoor Tamping or Plugging

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HIGH SHOCK EFFECTS

Shock Wave

Rock is DisplacedInto HoleHigh Pressure

Gas PenetratesInto Hole

PRE-COMPRESSION CAUSESIN DELAYED HOLES

COMPRESSIVE SHOCK WAVEHOLE TO HOLE

UndetonatedCharge

DetonatingCharge

Detonation Front

Plasma FrontOutruns Detonation

Plasma FrontCauses LateralPre-compression

Cross Section

Channel Effect

CONVENTIONAL VERSUS ELECTRONIC DETONATORS

SHIELDED BURN CUTS POWDER FACTOR  Face area Powder Factor Range

(m2) (ft2) (Kg/m3) (lb/yd3)low high low high

3.7 40 3.3 7.0 5.5 11.74.6 50 2.9 6.3 4.9 10.55.6 60 2.7 5.7 4.5 9.66.5 70 2.4 5.2 4.1 8.77.4 80 2.0 4.4 3.4 7.48.4 90 1.8 3.8 3.0 6.59.3 100 1.5 3.1 2.5 5.3

18.6 200 1.2 2.6 2.0 4.427.9 300 1.0 2.1 1.6 3.537.2 400 0.8 1.8 1.4 3.046.4 500 0.8 1.6 1.3 2.7

25 50 75 100 125

1.0

2.0

3.0

kg/m3 lb/yd3

0.0

Face Area ( )m2

Face Area ( )ft 2

200

1.0

2.0

3.0

4.0

5.0

400 600 800 1000 1200

TUNNEL AND SHAFT ROUNDSSPECIFIC CHARGE (Powder Factor)Based on Area of Face

Adapted from Rock Blasting and Explosives Engineering, Persson et al. 1993

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CASE HISTORIES

CONNECTION TO EXISTING CONCRETE-LINED PENSTOCK

ResinDowels

11000

Existing Passage

Bulkhead

Wet Dry

2 0 0 0

Excavation Line

Elev. 558PlaftformBarrier

C o n c r e t eD e m o l i t i o n

I f D a m a g e d

ProbeHole

123457/8

9/10

10/11

11/12

6

12/13Existin gT u n n e lF a ce

>=1300

4400

5050

X

X XX

Buffer Holes

Trim Holes

Blastholes

Trim Holes

Buffer Holes

Trim Holes

For Two-StageRounds Blast the CenterFirst and then the Remaining PerimeterAdjust to size of Face

DRY LAKE TAP

3' Concrete--removedby mechanical methods

Shaft Liner

Last SlashBlast

12345678

general firingsequence

SLASH ROUND LOAD

NEVER TampPrimer Sticks

12 to 18 inch Collar

REGULAR BLASTHOLE LOAD

8-in.Collar

Collar Plug

Tamped1/2 stick(1 1/4 X 12)

Tamp only the last stick

(1 1/4 X 12)Emulsion or semigelatin dynamite

Trim Explosive1/2 Stick (Primer)

SMOOTHWALL PERIMETER

8-feet folded 200 Grain Detonating CordTaped to Primer Stick

(7/8 x 24)Trim Explosive@ > 0.33 lb/ft

TVA BLUE RIDGE DAM LOW LEVEL OUTLET

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CONDIT DAM LAKE TAP*Careful Probing*Redundancy

KOYNA WET LAKE TAPS

300

Pipe Spacers or wood blockingto align TemplateNormal to desireddrilling alignment(Do not cover holes)

Hoisting anchor boltwith attchment ringsecured with resincartridges

Hoist template intoposition with fourchain hoists

Hoisting Eye-Bolt

860 +/-

900 mm anchor boltssecured with resincartridges

INSTALLED TEMPLATE (Section A-A)

92mm Hole 2mm Pipe Wall +/-

636.4

800150

150

150

212.13 212.13

800

106.06

BOTTOM PLATE andLIFTING POINT Details

150

FOLSOM DAM TUNNEL

Roadway

Trunnion

RadialGate

Trunnion Anchor

6 x7'Air IntakeTunnel

32'

39'

89'

ConcreteMonolith

Potential Water Level

CAVATATION IN OUTLETS

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AERATION TUNNEL

Radial GatesRadial Gates

SprayWallSprayWallSprayWall

New 192.5-ft Tunnel

Down Stream Face SprayWall Portal

Existing 222.5-ft Tunnel

New 6 x 7 ' TunnelExisting 5-ft Round Tunnel

CONCRETE MONOLITH

Plan View Section

Down Stream View

Work PlatformWork Platform AccessAccessWalkwayWalkway

BLAST EFFECTS MEASUREMENTS

Criteria Definedby Scaled Tests

StrainStrainGaugeGauge

Strain vs Scaled Distance

10

100

1 000

10 000

1.0 1 0.0 10 0.0

Scaled Dis tance (ft/lb^0.5)

Mic

rost

rain

ininStrainPeak /900

FOLSOM DAM TUNNEL BLASTS

5 Sticks --(1 1/8 X 8) Non-NG Dynamite

BLASTHOLE LOAD

(7/8 x 24) NG-Trim Cartridge

SMOOTHWALL PERIMETER LOAD

Doubled 200 Grain Detonating Cord

Drill 4.5 feet.to break 4 feet

Stemming

Stemming

BLASTHOLE LOAD SmoothwallHoles

Open 3" Cut hole

6 ft

7 ft

LP Delay No.

1

2 1/2

5

2 1/24

6

10

1414

5

6

11

11

11

10

10

11

10

10

10

10

13

10

42 ms

42 ms Lead In

9

1/2

11 11

11

121213

11

3

1 1/2

4

9

3

8 8

7

22

1 1/2" Dia.holes

AERATION TUNNEL IN FOLSOM DAM

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FOLSOM DAM AERATION TUNNEL

Radial GatesRadial Gates

SprayWallSprayWallSprayWall

New 192.5-ft Tunnel

Do wn Stream Face SprayWal l Por ta l

Existing 222.5-ft Tunnel

N ew 6 x 7' Tun nelExisting 5-ft Round Tunnel

CONCR ET E M ONOLITH

Plan View Section

Down S tream View

Work PlatformWork Platform AccessAccessWalkwayWalkway

DETROIT SINKING CAISSONCaisson Toe

Pillars

R2

R3

R4

R1

RoomsP4

P1

P1

P2

P3

34'

Caisson

4.5 ft

3 ft

LoweredPosition

Line/Split Hole

5 ft

ROOM ROUND PILLAR ROUND

DECOUPLED CHARGES BLASTING PILLARS

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VIBRATION AND AIR-OVERPRESSUREPREDICTION AND

CONTROL

AIR-OVERPRESSURE LIMITS

USBM RECOMMENDATION from RI 84851

Lower Frequency Limit of Measuring System Maximum Level

0.1 Hertz high pass system Flat Response 134 Peak

2 Hertz high pass system Flat Response 133 Peak

5 or 6 Hertz high pass system Flat Response 129 Peak

C- weighted system for eventswith duration less than 2.0 sec.

Slow Response 105 Peak

LOGARITHMIC SCALE!

xpsiLogdBDecibels

109.220)( 910

dBxLogdBDecibels

thenpsipressureAbsoluteIf

151109.21.020)(

:,1.0

910

dBxLogdBDecibels

psipsipressureAbsoluteExample

130109.201.020)(

01.0)(:

910

pressurerealinincreasefoldatoequatesDecibelsinincreaseA 10%16

Noise Control

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AIR-OVERPRESSURE STEMMING AND DIRT & MAT COVER

NOISE MITIGATION EFFECT OF “CAP SCATTER”

Predominant frequenciesof motion > 40 Hz.

LP #8 (2,500 ms)

Detonator TimingError "Scatter"

NominalFiring Time(2,500 ms)

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ELASTIC STRAIN WAVES

DetonatingCharge or otherImpulsiveDisturbance

Wave extent

Abbreviations:SH = Shear wave, horizontalSV = Shear wave, verticalR = Rayleigh waveP = Compressional wave

R

SH

SV

P

ATTENUATION RATEEnergy is 25 timesEnergy is 25 timeslower in groundlower in ground1600 feet away1600 feet away

Distance 0 100 200 400 800 1600 (feet)

Energy 5.0 4.0 2.0 1.0 0.5 0.2 (ips)

Blast Charge Blast Charge Body WaveBody Wave

Surface WaveSurface Wave

VIBRATION AND AIR-OVERPRESSURE MONITORING

PLOTTING MOTION

1 2 3

TIME

AMPLITUDE

START

BASELINE

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Velocity of Particle Motion or Air Overpressure Plottedwith respect to time

Event Duration

BackgroundNoise

PeakAmplitudePP

V or

dB

L (p

si)

TIME

BaseLine

T1 CYCLE

IMPORTANCE OF FREQUENCY AND DURATION

15

10

5

-5

-10

-15

0

KHS45 - Feb 7LOMA PRIETA QUAKE - 1989

Duration = 36 SecondsMaximum PPV = 13.0 in/sFrequency = 0.8 HzDisplacement = 2.5 inches

0 10 20 30 40

Duration = 0.8 SecondsPPV = 3.2 in/sFrequency = 84 HzDisplacement = 0.006 inches

TIME (Seconds)15

10

5

-5

-10

-15

0

CONCRETE MOTION AT YUBA - NARROWS 2 PROJECT

Displacement and corresponding strain causedby Earthquake is 416 Times greater than that ofHigh-frequency Blast-Induced Motion

PPV(in/s)

PPV(in/s)

BLAST VIBRATION CRITERIA

1

FREQUENCY, Hz

PAR

TIC

LE V

ELO

CIT

Y, in

/s

0.1

0 .2

0.4

0.6

0.8

1

2

4

6

8

10

0.75 in/s

2.0 in/s

0.50 in/s

2 4 6 8 10 20 40 60 80 10030

40

10

USBM RI 8507 Safe PPV Curves - Dashed Lines

Plaster & LathDrywall

Constan

t 0.008 in

Displac

ement

Constan

t 0.03 in

Displac

ement

1) Intended for prevention of cosmetic damage in plaster-lath and gypsum drywall.

2) Too often misapplied to protect new or cured concrete structures.

3) These limits can make some work impossible or needlessly increase cost.

VIBRATION IMPACT TO ROCK

Reduction in Quality (%)

0

20

40

60

80

100

Peak Particle Velocity (mm/sec x 1000)

Peak Particle Velocity (in/sec)

0 1 2 3 4

Approximate adjustment of rock mass quality after vibration. After Page 1987

0 40 79 118 157

"weak" rockQ<4

MRMR<20

"fair" rockQ-4

MRMR - 56

"good" rockQ>50

MRMR > 80

Effect(in/s) (mm/s)

10 254 No fracturing of intact rock10 to 25 254 to 635 Minor tensile slabbing will occur25 to 100 635 to 2540 Strong tensile and some radial cracking

> 100 >2540 Complete breakup of the rock massAfter Bauer and Calder (1971)

Peak Particle Velocity

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ORIARD Mass Concrete PPV LimitsConcrete Age Allowable

From Batching PPV - mm/s (in/s)

0 to 4 hours 102 (4) x DF4 hours to 1 day 152 (6) x DF1 to 3 days 229 (9) x DF3 to 7 days 305 (12) x DF7 to 10 days 375 (15) x DF10 days or more 508 (20) x DF

Distance Factors (DF):

Distance = 0 – 15 m (0 – 50 ft) DF = 1.0Distance = 15 – 46 m (50 – 150 ft) DF = 0.8Distance = 46 – 76 m (150 – 250 ft) DF = 0.7Distance > 76 m (250 ft) DF = 0.6

Oriard and Coulson – 1980

Distance Factors are intended to reduce PPV levels at greater distances to account for higher displacements caused by lower frequencies.

Must also consider:

2) Block motion and ground rupturing potential.

1) Structure height and confinement

2) Condition or structure and reinforcement.

DISPLACEMENT AND STRAIN

0.7 in/s@ 57 Hz

0.15 in/s@ 10 Hz

1) Displacement at low frequency motion greater than at peak!

2) Time history reveals more than summary of motion at PPV

Displacement = PPV / (2 pi f )

RELATIVE EFFECTS

15-lbSledge

Hammer

18-WheelTruck Jump 20-mph

Wind 10 deg.Temp Chg. 50-mph

Wind 7-dayWeather

Chg.

Safe Limitfor Drywall Safe Limit

forConcrete

AspectSeismic

PPV

0

2

4

6

8

10

12

14

16

18

20

PPV

2.02.02.0

20.0 ips20.0 ips20.0 ips

5.125.125.12

0.550.550.55 0.50.50.52.62.62.6 3.23.23.2

6.76.76.75.05.05.0

RELATIVE VIBRATION IMPACTS

More than 20 timeshigher than motionpredicted at Propertiesclosest to CSO Blasts

Buried Raw Eggs and LightbulbsBuried Raw Eggs and LightbulbsSurvive 5.0 in/s PPVSurvive 5.0 in/s PPV

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VIBRATION AND NOISE CONTROL* Structural and Cosmetic Damage* Human Response* Animal Response

ACME

GFR

HUMAN RESPONSE

0.1 1 10 100 1000

Parti

cle

velo

city

(in/

sec)

(mm

/sec

)

Stronglyperceptible

ISO reduced comfort

Severe

Distinctlyperceptible

Barelyperceptible

0.01

0.1

1

10

1

10

100

Exposure time (s)

After Wiss and Parmalee (1974)

ANIMAL RESPONSE

"Pete" the Black Rhino"Pete" the Black RhinoElephantsElephantsRed PandasRed PandasNaked Mole RatsNaked Mole Rats

DRILLING SMALL HOLES FOR SHAFT BLAST

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REDUCING CHARGE PER DELAY

SeparateTrunklinefor eachquadrant

+0

+42+84

+126

PREDICTING PPVm

WDKPPV

Where:

K and m are constants defining initial vibration and rate of attenuation

D = Distance between blast and prediction location (m or ft)

W = Maximum charge weight per 8-millisecond delay (kg or lb)

DIMENSIONAL SIMILITUDE

W 1 = 100 kg

Point of PPV Measurement

W 2 = 1 kg

D = 100 m

D = 10 m

Point 2 Point 1

so PPV 1 PPV 2

PPV = K (Ds)m

101

10 Ds 210100

100 Ds 1

Ds 1 = Ds 2

LINEAR IN LOG-LOG SCALE

m

WDKPPV

WDDs

KLogDsLogmPPVLog

bxay Log Ds

Log ppv

Slope = mLog K

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ORIARD PPV RANGE 6.1 sDKPPV

  6.1 sDKPPV

6.1

160

WDPPV

Where: D = Distance (ft)W = Charge‐per‐Delay (lb)

6.1

1141

WDPPV

Where:D = Distance (m)W = Charge‐per‐Delay (kg)

CASE STUDYLEGEND

- Plaintiff's Home

- Monitoring Location

2510'

1565'

Location ofMiningBoundry(April 2002)

SCALE

0 500' 1000'

N1

2

3

5

6

4

- Monitoring Location No.1

CURVE SLOPE

Harrod PPV Curve

0.010

0.100

1.000

10.000

100.000

1000.000

1.0 10.0 100.0 1000.0 10000.0

Ds

PPV PreSeisTek

Blastech

86.0

7.10

sDPPVFitBest

Based on 329 Data Points. Correlation coefficient = 0.782

86.03.22%95 sDPPVUpper

CRACK DILATION

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COMPARABLE EFFECTS

Comparative Changes in Crack Widthmicro inches

Crack Location Outside Inside Basement Inside Bedroom notes(Wall Material) (Brick wall) (Concrete Block) (Dry Wall )

Effect

lightOccupant 400 250 200 adjacentActivity pounding

Wind??? 50

Weather/ (10,000) 6000 (750) (daily)Environmental (750)

Blasting 200 200 50 0.14 ipsmaximum

Wind

* Environmental effects on existing cracks in structures were 50 times greater than those caused by blasting

DAMAGE CAUSES

Temperature ChangesHumidity DifferencesSoil Expansion or Collapse Water DamageWind and Weather Aging ProcessesWear and Tear

CADOMIN ALBERTA BLASTING NEAR NEW CONCRETE

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CHARACTER OF MOTION

8 ft

Blast-ProofForm and NewConcrete

Shot rock left against toe of face to suppress flyrockand air-overpressure

SUMP AREA

PPV > 30 in/sFrequency: >1,000 HzDisplacement: 0.0048 in(Hair thickness: 0.008 in)

BLASTING NEAR SOLDIER PILES

Direct rupturing causes damage.High PPV at high frequency motion with light decoupled charges does not!

BLASTING NEAR FREEZE PIPES BLASTING NEAR FREEZE PIPES

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STRAIN CALCULATIONS CHARGE RELIEF AND SWELL* Free Face* Orientation* Timing

VbVs = 1.3 Vb

Swell factor Principle

If swell factor (SF) = 1.3Swelled Volume (Vs) = Vb x SF

Swelled volume (Vs) Bench volume (Vb) 1 .2 m (4 ft)

RISK MANAGEMENT

SAFE & EFFICIENT

BLASTING

Ov

ers

igh

t

1

RISK INCREASES WHEN ANY OF THESE SUPPORTING MEASURES AND CONTINUITY

OF PURPOSE ARE WEAK

3

4

2

Preq

ualificatio

n

De

sig

n

Sp

ec

ifica

tion

s

BEST MANAGEMENT PRACTICES

• Evaluate Area Property- Pre-construction Inspections

• Apply Blasting Controls- Charge Weight Limits- Noise Control Measures

• Public Communication- Project Hotline- Open Meetings

• Government Approvals• Perform Work Safely• Continuous Blast Effects Monitoring

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SUCCESSFULLY MANAGING HIGH-RISK BLASTING WORK

There are four layers of expertise:

The first layer starts with designers who develop specifications, geotechnical reports, and other documents that:

1) define challenges of the work; 2) limit allowable methods; 3) specify performance requirements and;4) establish experience requirements for key

participants

SUCCESSFULLY MANAGING HIGH-RISK BLASTING WORK

The third layer of risk management is expected from third-party blasting / vibration consultants representing the contractor.

SUCCESSFULLY MANAGING HIGH-RISK BLASTING WORK

The last layer of risk management is delivered by a third-party construction manager, supported by inspectors, project designers, and additional specialists as needed.

QUESTIONS?