icwes15 - challenging design: foundations for tall buildings. presented by ms frances badelow, aust...
TRANSCRIPT
COFFEY GEOTECHNICS
Challenging Design: Foundations for Tall BuildingsHelen Chow & Frances Badelow
COFFEY GEOTECHNICS
Introduction
• SuperTalls – 300m+• Challenging Task - Use
innovative design approaches• Innovative and Cost effective
foundation – Piled Raft83502411
680
550
236
13370
281611110
100
200
300
400
500
600
700
800
900
1940 1950 1960 1970 1980 1990 2000 2010 2012
Year
No. o
f Bui
ldin
gs
200m+
300m+
Data from Council on Tall Buildings and Urban Habitat
COFFEY GEOTECHNICS
Design ProcessPhase 1 – Subsurface Exploration
• Desktop study
• Site specific geotechnical investigation
•In-situ and laboratory testing
Phase 2 – Foundation Design
• Develop geotechnical models and parameters
• Preliminary foundation design
• Refine design
• Detailed design• Foundation Performance• Retention System• Seismic Assessment• Impacts on adjacent properties
Phase 3 – Foundation Testing and Monitoring
• Pile Load Test
• Performance Monitoring
COFFEY GEOTECHNICS
Foundation PerformanceOverall Stability • Ultimate load combinations
applied• Ultimate pile capacities
reduced by • Condition satisfied if
foundation system does not collapse
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Foundation PerformanceFoundation Settlement• Working load applied• Foundation resistance and stiffness unfactored• Condition satisfied if settlement and angular rotation within
allowable limits
COFFEY GEOTECHNICS
Incheon 151 Tower, Korea• Located in Songdo, South
Korea• 151 Storeys High (Height =
601m)• 8.5m Deep Basements• Geotechnical designer –
Coffey & Jin-Young ENC• Structural designer –
Thornton Tomasetti• Architect – John Portman
& Associates
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~ 30m
~ 20m
Incheon 151 TowerGround Conditions
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Incheon 151 Tower
• Ground Conditions– Divided into 8 Zones
Ground Conditions
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Foundation Layout: Raft thickness: 5.5m thick embedded into UMD• 172 piles @ 2.5m diameter• Lengths: 36m to 66m (2 x pile diameters socket length)
Challenges:• Variation in Ground Conditions• Interaction of Pile Group• Lateral Stability
Incheon 151 Tower
88m
77.5m
COFFEY GEOTECHNICS
PLAXIS 3D - Vertical Loading
200m
200m
100m
Incheon 151 Tower
COFFEY GEOTECHNICS
Incheon 151 Tower
PLAXIS 3DGARP – Overall Settlement = 0.067m
Differential Settlement = 1/2600
Angular Distortion = 0.07°
Settlement of Foundation
600m
Foundation
COFFEY GEOTECHNICS
Incheon TowerHorizontal Loading • Critical Issue due to high wind load
COFFEY GEOTECHNICS
Nakheel Tall Tower, Dubai
Nakheel IncheonBurj Dubai
COFFEY GEOTECHNICS
Nakheel Tall Tower• More than 200 Storeys High (Height > 1000m)• Centre piece of Nakheel Harbour• Ground Conditions
Sand20m
<2.5m Gypsum
>75mCemented Carbonate Siltstone
COFFEY GEOTECHNICS
Nakheel Tall Tower• Ground Conditions
– Compressibility controlled by Bond Yield Strength– Imposed Stress < Bond Yield Strength
• Very Stiff Material
Strain, e
Stre
ss, s
Bond yield strength
COFFEY GEOTECHNICS
Nakheel Tall Tower
Foundation Layout:
• Raft thickness: varies up to 8m• 392 Barrettes –2.8m x 1.2m
2.8m x 1.5m • Lengths: 37m , 42m & 72m
COFFEY GEOTECHNICS
Nakheel Tall Tower• Geotechnical Peer Review
– Review Geotechnical Designers’ Report and Design Method
– Independent Foundation Analyses • Overall Stability • Settlement < 0.1m
1000m
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Conclusion• Good Understanding of Ground Conditions• Critical Issue – Horizontal Loads• Good Communication between Structural and
Geotechnical Engineers
COFFEY GEOTECHNICS
Thank You