Introduction
Fugro LOADTEST Overview Static load tests Previous/existing technology Developments
STATIC LOAD TESTING O-cell® BiBi-directional testing State of the art Dr Melvin England Fugro LOADTEST
O-cell® static loading tests Conclusions
Date 27th January 2010
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LOADTEST Inc started in 1991 Operating around the world from 5 LOADTEST offices 45 staff – mostly engineers – Some of our staff are recognised leading experts in various forms of pile testing €10 M turnover (1/2 USA) Portable test systems allow easy access to very remote locations LOADTEST acquired Fugro as new owners in Jan 2009 and LOADTEST can now operate from any of the Fugro offices around the world and call on the resources of Fugro where necessary. www.fugro.com www.fugro.fr
Oil-rig module used as Kentledge
Date 27 January 2010
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Reaction systems for static load tests:
Fugro LOADTEST
Date 27 January 2010
Date 27 January 2010
Dead load (kentledge) A structure over the test pile Ground anchorage either by tension piles or ground anchors. Bi-directional (Osterberg-cell) Date 27 January 2010
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Test on group of 9 precast piles to 20MN
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Date 27 January 2010
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Ready assembled reaction systems
Reaction systems
BiBi-directional testing ABU-DHABI
2MN
4 MN 5.5 MN
10 MN
GREAT MOSQUE ABU-DHABI SHEIKH ZAYED BRIDGE ABU-DHABI
Date 27 January 2010
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Zone of influence
Date 27 January 2010
Zone of influence
Kentledge
Reaction beam on anchor piles
Date 27 January 2010
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Zone of influence
Date 27 January 2010
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Zone of influence
Kentledge on piles
Bi-directional test
Date 27 January 2010
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Date 27 January 2010
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Kentledge collapse
Safety considerations
Due to platform/ground failure
From FPS Load testing handbook 2006 Date 27 January 2010
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Reaction Beam collapse
Date 27 January 2010
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COMPLETELY AUTOMATED
Due to tension bar failure
From FPS Load testing handbook 2006 Date 27 January 2010
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BIBI-DIRECTIONAL OO-CELL LOAD TESTS
Date 27 January 2010
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How it works
Introduction To Osterberg Cell technology Advantages & Limitations Examples Current usage and costs
Date 27 January 2010
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Date 27 January 2010
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Bi-directional schematic
Date 27 January 2010
Bi-directional schematic
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Comparison of O-cell and Traditional Tests
Date 27 January 2010
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O-cell Static Load Test Advantages
Very high loading capability
Gets load into rock sockets (or other zone of interest)
Cost, safety and space advantages
No additional reaction system needed
Doubles effective jack load
Can measure directly skin friction and end bearing
Post-test grouting techniques allow for testing of production piles
Date 27 January 2010
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Date 27 January 2010
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Single O-cell – Bearing Plate Assembly
O-Cell Instrumentation
Top and Bottom Plates are Welded to the O-cell O-cell / Plate System is Welded into the Rebar Cage Date 27 January 2010
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Date 27 January 2010
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O-cell Test Components
Date 27 January 2010
O-cellTM fitted with bearing plates attached to cage
MultiMulti-cell assembly - attaching OO-cells to bottom plate www.fugro.com www.fugro.fr
Date 27 January 2010
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Cone-shaped tremie guide
MultiMulti-cell assembly - attaching top plate Date 27 January 2010
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Other O-cell Assemblies
Lifting the Cage and Attached O-cell Assembly
Once the Cage With Attached O-cell is Carefully Lifted, it is Installed into the Shaft Excavation Date 27 January 2010
Date 27 January 2010
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O-cells can be Placed at two Levels in the Shaft to Isolate Distinct Shaft Elements Date 27 January 2010
The O-cell Need Not be Attached to a Rebar Cage www.fugro.com www.fugro.fr
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Multilevel testing
Multilevel testing Stage 1
Middle cell closed Test is performed in stages
Lower cell pressurised
Date 27 January 2010
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Date 27 January 2010
Multilevel testing Stage 1
Multilevel testing Stage 2
Downward movement below bottom O-Cell
Middle cell pressurised
(MN) 0.0
5.0
10.0
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15.0
20.0
25.0
30.0
0 -10 -20 -30 -40
Lower cell draining
-50 -60 -70 Date 27 January 2010
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Date 27 January 2010
Multilevel testing Stage 2
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Multilevel testing Stage 3
Downward movement below middle O-Cell (MN) 0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
50.0
55.0
60.0
Middle cell pressurised
0 -5 -10 -15 -20 -25 -30
Lower cell hydraulically closed
-35 -40 -45 Date 27 January 2010
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Date 27 January 2010
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Multilevel testing Stage 3
Multilevel testing Stage 3 30 25 20
Downward movement below middle O-Cell
15
(MN) 0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
50.0
55.0
60.0
10
0 5
-5 0
-10
0.0
-15 -20 -25
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
50.0
55.0
60.0
(MN)
End of Stage 2 testing, Bottom O-cell hydraulic lines closed allowing load transfer to end bearing.
Upward movement above middle O-Cell
-30 -35 -40 -45 Date 27 January 2010
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Date 27 January 2010
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Test Setups
Equivalent top load-settlement curve Load (MN)
Settlem ent (m m )
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
110.0
120.0
130.0
0 -10 -20 -30 -40 -50 -60 -70 -80 -90 -100 -110 -120 -130 -140 -150
World record – 160 MN
Date 27 January 2010
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Advantage – Space Requirements
Date 27 January 2010
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O-cell Test Limitations Preselected shaft
2000 ton Conventional
3000 ton Conventional
Maximum load limited by weaker of end bearing or skin friction Test results need interpretation Top of the pile is not tested structurally tested
2000 ton O-cell Test Date 27 January 2010
3000 ton O-cell Test www.fugro.com www.fugro.fr
Top load movement curve must be calculated From the sum of measured behaviour; From the sum of modeled behaviour; Finite element; Date 27 January 2010
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Analysis of O-cell test results
Equivalent TLT Assumptions
‘Rigid’ shaft (includes OLT elastic compression) L-Movement compatibility, friction and end bearing Corrections for direction of skin friction Factor = 1 clays, rock sockets Correction for direction of loading can be used Factor = 0.80 Equivalent tension test Correction for additional TLT elastic compressionconservative, iterations not needed Good practical agreements Date 27 January 2010
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Sum of measured results
Date 27 January 2010
Date 27 January 2010
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Measured behaviour Sum of components
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Date 27 January 2010
Measured plus additional elastic shortening
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Comparison test curves Kentledge Test versus O-cell equivalent top load-settlement curve 0 -10 -20
Settlement (mm)
-30
O-cell Test Kentledge Test
-40 -50 -60 -70 -80 -90 -100 -110 -120 0
Date 27 January 2010
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Date 27 January 2010
2
4
6
8
10
12 14 16 18 Top Load (MN)
20
22
24
26
28
30
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Advantage – High Loads
Incheon 2nd Link, Korea
World Record History Location
Diameter
Depth
Maximum Load
Ohio River Bridge, Kentucky ( 1992 )
1.8m ( 6 ft. )
36m ( 117 ft. )
54 MN ( 6,200 tons )
St. Mary’s River, Georgia (1996 )
1.5m ( 5 ft. )
23m ( 75 ft. )
65 MN ( 7,300 tons )
Penang, Malaysia ( 1996 )
6x1m barrette
91m ( 300 ft. )
97 MN ( 11,000 tons )
Apalachicola River, Florida ( 1997 )
2.75m ( 9 ft. )
39m ( 127 ft. )
133 MN ( 15,000 tons )
Tucson, Arizona ( 2001 )
2.4m ( 7.9 ft. )
41m ( 135 ft. )
151 MN ( 17,000 tons )
Pomeroy - Mason WV, Ohio River
2.4m (8 ft.)
26m (86ft.)
163 MN (18,400 tons)
2nd
2.4m – 3.0m (8 ft. – 10ft.)
67m (220ft.)
279 MN (31,350 tons)
Crossing Incheon Korea Date 27 January 2010
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Incheon 2nd Link, Korea
Date 27 January 2010
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Incheon 2nd Link, Korea
Date 27 January 2010
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Oste rbe rg Ce ll Loa d-Move me nt Curve s
Date 27 January 2010
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Advantage – Rock Sockets
60
OLT
TLT
50
P
40
Displacement ( mm)
30
Overburden
20 Upwar d Top of O- c ell
10 0
-10 Downwar d Base of O- c ell
Rock
-20
Q
Ub & Eb difficult to interpret
-30
-40 0
20
40
60
80
100
120
140
160
• Uncertain Distribution
• Less Distribution Uncertainty
• Little or No Top Load Gets into base
• All Load into Socket
• May Need Model Shaft
• Can Test Full Scale
O-ce ll Gr os s Load ( M N ) Date 27 January 2010
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Date 27 January 2010
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Applications
O-cells in CFA piles
Bored piles (wet and dry) CFA piles Driven Piles – Cast in-situ (with and without permanent steel casing) – Precast – Steel tubular piles Barrettes
Date 27 January 2010
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Date 27 January 2010
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O-cells in CFA piles
O-cells in CFA piles
Maximum size/loads tested to date Pile Diameter [mm]
Pile Length [m]
O-cell Diameter [mm]
Mobilised Load [MN]
Date 27 January 2010
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O-cells in PRECAST piles
Date 27 January 2010
600
750
900
900
38
40
35
36
405
540
660
2x540
17.5
32
32
46
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Barrettes
Sizes tested to date Pile Section 300 mm 450 mm 600mm 750 mm Date 27 January 2010
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Date 27 January 2010
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St. Petersburg, Russia
St. Petersburg, Russia
30 MN Reaction system
• 60 m deep
90 MN O-cell test
• 90 MN capacity Date 27 January 2010
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Date 27 January 2010
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Maximum size/loads tested to date
Kiev Ukraine: 90 MN Barrette
7.0m x 1.2 m 50 m deep loaded to 110 MN
T shaped: 2.8 x 4.0 m Multiple tremie pipes Date 27 January 2010
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Maximum size/loads tested to date
loaded to 70MN Date 27 January 2010
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Applications: Bridges
Cooper river
Jiangsu Sutong
Panama 2nd Bridge Confederation
UAE: Multilevel; 80 m deep; 220 MN mobilised Date 27 January 2010
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Date 27 January 2010
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Applications: Buildings
Osterberg Cells Installed Actual
Projected
350 300 250 200 150 100
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09
08
20
20
06
05
04
07
20
20
20
20
02
01
00
03
20
20
20
98
99
19
Date 27 January 2010
20
96
97
19
19
19
94
93
95
19
19
Date 27 January 2010
19
92
0 19
Venetian Hotel, Las Vegas, NV
50
91
Four Seasons Hotel Miami, FL
19
One Raffles Quay, Singapore
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O-cell Tests World-wide COMPARISON OF LOAD TESTING COSTS CONVENTIONAL VS. O-CELL
O-cell
COST/ MN
Conventional
Key 0 1-10 11-20 21-30 >30 Upcoming/In progress
1
10
100
1000
TEST LOAD - MN Date 27 January 2010
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Bi-directional testing
Disadvantages
•No external reaction system
•Pile test not exactly as a full load test.
•No anchor piles
•Maximum load applied limited
•Only half the stresses applied to the concrete •For large tests a significant cost saving Date 27 January 2010
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Conclusions
Advantages
•Little or no heavy transport requirements
Date 27 January 2010
Bi-directional testing routinely reveals more about the geotechnical behaviour than a traditional top-down loading test. (Over 1400 tests worldwide). O-cell testing much safer than traditional top-loading
•Jack is expendable and needs fitting during pile installation www.fugro.com www.fugro.fr
As the test loads increase the more cost effective and attractive O-cell testing becomes.
Date 27 January 2010
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Providing confidence in foundations through load testing - around the world. www.loadtest.com
Thank You
A member of the Fugro Group of companies Florida, USA Date 27 January 2010
UAE
LONDON
SINGAPORE
KOREA www.fugro.com www.fugro.fr
Date 27th January 2010
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