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62nd Annual Meeting • 2005 • Peter Kiewit Sons’, Inc.
62nd Annual Meeting • 2005 • Peter Kiewit Sons’, Inc.
Deep Ground Improvement using
Explosive Compaction
Dario Gnoato - Western Canada
Presentation Outline
• Background on the Existing Dam • Why the Need for Upgrading
• Explosive Compaction (EC) • What is it?
• How does it Work?
• Explosive Compaction Program • Panel Development
• Drilling and Casing the Holes
• Blasting
• Conclusion
Seymour Dam - Vancouver, BC
• Built in 1959
• Vancouver’s main Water Reservoir
• Annual Rainfall exceeds 189 inches
• 90ft high x 1300ft Concrete Structure
• 90ft high x 1600ft Earth Filled Structure
Zone to be Improved
0 to 20ft Cut & Fill
20 to 50ft Dynamic Compaction
50 to 80ft Explosive Compaction
What is Blast Densification?
“A Way to Densify the Ground Without Having to Remove and Replace It”
How Does Blast Densification Work?
Blast Charge
Drill Hole
Blast Densification Pressure Waves
• Compression & Shear Stress Waves Travel Through the Granular Soil & Water
Blast Densification Displacement
• Displaced Material Settles to a Denser Configuration
Explosive Compaction Program (EC)
Three Components
1. Development of EC Panels
2. Drilling & Casing the Blast Holes
3. Blasting the Holes
Explosive Compaction Panels
1 Panel 1 Excavation: 22,100 yd3
13 15
14 16
Panels 13 - 16 Excavation: 2,400 yd3
2 3 Panels 2 - 3
Excavation: 45,600 yd3
4 5 6 8
Panels 4 - 8 Excavation: 44,100 yd3
9
Panel 9 Excavation: 1,900 yd3
10 11 12
Panels 10 - 12 Excavation: 32,700 yd3
EC Earthworks
Basic Equipment • 35ton Rock Trucks • 345 Excavators • D6 Dozers • 148,000yd3 total
• Costs $2.90/yd3
(NIC maintenance) • Production 150yd3/hr
EC Earthworks - Problems
• 35% of Native is 6yd3 + boulders
• Largest to date 180yd3
EC Drilling and Casing
• 780 – 70ft x 6“ Cased Holes • Water Tight 4“
PVC casing Installed
EC Drilling Equipment
2 – Down the Hole Hammer Reverse Circulation Drills
Production = 10ft/hr = 0.27MHr/ft
EC Drilling Equipment
Symmetrix Drilling System by Rotex Modular Drilling System, consists of:
1. Casing Shoe that is Welded to the First Casing
2. Ring Bit that Rotates Freely on the Casing Shoe
3. Pilot Bit that Locks to the Ring Bit
EC Drilling Equipment
EC Charge Pattern
• 20 Drill Holes/Blast • 4 Decks/Hole = 80
Decks/Blast • 2400 lbs Explosive/
Blast • 0.3 lbs/yd3 Powder
Factor • Each Bench is
Blasted 3 Times
25ft
25ft
15ft
55ft
#4
#3
#2
#1 55lb
42lb
11lb
11lb
EC Blasting – Equipment
• Orika i-kon Digital Detonators
• Timing from 1st to the 80th Deck can Not Vary More than 0.1%
• Totally Programmable • 2-Way Communication with
Blast Control Equipment • Delay Time 0-15,000ms with
1ms Increments • Very Expensive - $45 vs $4
for standard Electric Type
Detonator
EC Blasting – Equipment
• Orica i-kon Logger • Communicates with
Detonators • Assigns the
Predetermined Time Delay
EC Blasting – Equipment
• Orica i-kon Blaster • Communicates with
Logger to Receive the Blast Data
• Communicates with Detonators for Final Check of the Status of all Detonators Prior to Blast
EC Blasting – Material
1. Dyno Nobel IREMITE TX • Cap Sensitive packaged
Explosive Emulsion • Resistant to Dead
Pressing • No Powder Headache • Water Resistant • Insensitive to Low
Temperatures
2. Dyno Nobel Pentolite Cast Booster • High Performance • Insensitive to Freeze/
Thaw Cycles
EC Charge Loading Procedure
• Dewater PVC Casing
Pipe to Minimize Hydraulic Shock Effects on Explosive Decks
• We Do Not want Sympathetic Detonation
EC Charge Loading Procedure
• Each Explosive Deck is Primed Using an i-kon Electronic Detonator + Pentolite Cast Booster
• Load Required Charge Weight of Iremite TX Explosive into each Deck
EC Charge Loading Procedure
• Each Detonator is Verified & the Firing Time is Input using an i-kon Logger
• Stemming Material is Loaded into Blast Hole
EC Charge Loading Procedure
• Once the Complete Pattern has been loaded, the Detonators are Wired into Series Circuit using i-kon specialized Clips & Harness Wire
• The Complete Blasting
Circuit is Checked & Verified Electronically using the i-kon Logger before Hook Up to the i-kon Blaster
EC Blast Equipment
EC Blast
EC Data Monitoring
• 6 Seismographs situated throughout the site, these are Used To Monitor Movements (Peak Particle Velocity)
Scaled Distance PPV vs. Rh/W1/2
1.0
10.0
100.0
1000.0
1.0 10.0 100.0 1000.0R/W^0.5 (m/kg^0.5)
Mea
sure
d PP
V (m
m/s
)
Pass 1 (measured)
Pass 2 (measured)
Pass 3 (measured)
Y=2500*X̂ (-1.5)
Y=4500*X̂ (-1.5)
EC Data Monitoring
• 18 Piezometers used to measure Pore Pressures at the Toe of the Existing Dam (6 vibrating wire, 6 strain gauge & 6 pneumatic type)
Electric Piezometer DH04-2A(E) - Panel 9A - Pass 2 Layout 2, Blast on October 18, 2004 (16:42:55)
200
205
210
215
220
25 30 35 40 45 50 55 60 65
Time (seconds)
Elev
atio
n of
Wat
er (m
)
DH04-2A(E)
Piezo. elev. 184.4 m
Time of Blast
18m = 59ft Water Head Increase
EC Data Monitoring • 9 Deep Settlement Posts • Over 100 Survey Shots Pre & Post Blast • Survey Monitoring of existing 84” diameter
Water Line that is 30yds from some of the Blasts
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
28-Apr-0
4
28-May-0
4
27-Jun-04
27-Jul-04
26-Aug-04
25-Sep-04
25-Oct-0
4
Date
Cumu
lative
Cha
nge i
n El
evat
ion
(m)
TMP-A TMP-B TMP-C TMP-D TMP-E TMP-F TMP-G TMP-H TMP-H2 TMP-I TMP-J TMP-K
TMP-L TMP-M TMP-N TMP - mg97 TMP - mg98 TMP - mg99 TMP-J1 TMP-J2 TMP-K1 TMP-K2 TMP-L1 TMP-L2
TMP-O TMP-P TMP-Q TMP-R TMP-S TMP-T
April May June July August Sept Oct
0.2m
0.1m
-0.1m
-0.2m
EC Data Monitoring
• Post Blast Standard Penetration Tests in order to Confirm Compaction
Extensive Blast Confirmation
• High Speed Video Camera to Monitor the Nonel Blast Tubes (80 tubes/blast)
• 80 Coaxial Cables/Blast, 1 per Deck • 1 High Speed Piezometer (10,000 readings/sec) • 1 Geophone set up at the Center of the Blast
Pattern to Record Transient Pressures • 6 Seismographs
Conclusion
• Settlements are 1 to 3 ft
• Dam Toe has Not Moved Laterally
• Owner Considers the Program Very Successful
• Why Do It this Way?
• Excavate and Replace $23.30/yd3
(NIC processing costs)
• Explosive Compaction $9.10/yd3
