sustainable foundations
DESCRIPTION
Sustainable foundations. Alternative title slide. Istructe south Stephen west. What is sustainability. Oxford English Definition: able to be maintained at a certain rate “conserving an ecological balance by avoiding depletion of natural resources”. Content slide. - PowerPoint PPT PresentationTRANSCRIPT
SUSTAINABLE FOUNDATIONSISTRUCTE SOUTH
STEPHEN WEST
WHAT IS SUSTAINABILITY
Oxford English Definition:
able to be maintained at a certain rate
“conserving an ecological balance by avoiding depletion of natural resources”
WHAT IS SUSTAINABILITY
Environment
EconomicSocial
Viability
Fair
Liveable
Sustainable Development
It’s about balance
WHAT IS SUSTAINABILITY
• Finding a balance
• Carbon accounting can be useful
• Consider the long term as well immediate
• Good design should lead to sustainability
• Foundation and sub-structure design can be used as offsets
Is this sustainable???
Not if it leads to this
SHOULD WE WORRY ABOUT SUSTAINABILITY
• Improve long term cost benefits
• Enhance Bid Potential
• EA Compliance
• Future Government Policy
FACTORS TO BE CONSIDERED
• Materials
• Manpower input
• Quantity of Foundation Positions
• Muckaway quantities
EMBODIED VS OPERATIONAL
Embodied Carbon Operational Carbon Whole Life Carbon
FACTORS TO BE CONSIDERED
• Materials
• Manpower input
• Quantity of Foundation Positions
• Muckaway quantities
• Site Impact – Contamination
Future Site re-use
SHOULD THE FOUNDATIONS FIT THE SUPERSTRUCTURE OR VICE VERSA
• Spaced load takedown for localised loading points
• Widened load application for spread foundations
• Can a basement help?
• Load vs Settlement
CONTAMINATION RISKS
• Worker Health and Safety
• Long term user impact
• Groundwater Quality
Contaminated Soil/Groundwater
Impermeable Layer
Protected Aquifer
Protect against downward
flow of contaminants
DEALING WITH MARGINAL GROUND
• Is this an opportunity?
• Improve or Bypass?
• Ground Types
DEALING WITH MARGINAL GROUND
• Is this an opportunity?
• Improve or Bypass?
• Ground Types organic soils, peat
soft cohesive soils
loose granular soils
waterlogged soils
DEALING WITH MARGINAL GROUND
• Is this an opportunity?
• Improve or Bypass?
• Ground Types
• Site wide or localised?
FOUNDATION OPTIONS
BYPASS IMPROVE
Piles Deep Footings
Vibro-concrete columns
Stone Columns
Remove & Replace
Soil Mixing
Surcharging
SUSTAINABLE PILING
• Auger based displacement piles – CFD/CHD
Compresses
+
Expands
column
SUSTAINABLE PILING
• Auger based – CFD/CHD
• Screw Piles
SUSTAINABLE PILING
• Auger based – CFD/CHD
• Screw Piles
• Driven options – closed end piles
SUSTAINABLE PILING
• Auger based – CFD/CHD
• Screw Piles
• Driven options – closed end piles
• Mitigating Contamination Impact
Contaminated Soil/Groundwater
Impermeable Layer
Protected Aquifer
Minimal disturbance
Piling – CFA, CHDOversize protective shaft
SUSTAINABLE PILING
• Auger based – CFD/CHD
• Screw Piles
• Driven options – closed end piles
• Mitigating Contamination Impact
• Energy Piles
GROUND IMPROVEMENT
• Lime/cement mixing
GROUND IMPROVEMENT
• Lime/cement mixing
• Dynamic compaction
GROUND IMPROVEMENT
• Surcharging
Increased Porewater Pressures
Surface Loading
GROUND IMPROVEMENT
• Surcharging
Increased Porewater Pressures
Surface Loading
Granular layer to
promote flow rates
Vertical drainage to promote more rapid
consolidation
GROUND IMPROVEMENT
• Wick Drains or Band Drains
GROUND IMPROVEMENT
• Wick Drains or Band Drains
GROUND IMPROVEMENT
• Wick Drains or Band Drains
• Stone Columns
GROUND IMPROVEMENT
• Wick Drains or Band Drains
• Stone Columns
Compacts soil as well as providing a drainage path
FOUNDATION RE-USE
• Growing opportunities
• Needs buy in throughout project team
• Requires record retention
• Testing of existing piles
• Foundation Removal
THE FUTURE
• Chance to be more brave!!!
• More rafts??
• Less unnecessary excavation??
THE FUTURE
• Chance to be more brave!!!
• More rafts??
• Less unnecessary excavation?? – Better Investigation
THE FUTURE
• Chance to be more brave!!!
• More rafts??
• Less unnecessary excavation?? – Better Investigation
• Better foundation records
• Pre-fabrication of foundation
THE FUTURE
• Chance to be more brave!!!
• More rafts??
• Less unnecessary excavation?? – Better Investigation
• Better foundation records
• Pre-fabrication of foundation
Is this sustainable?? – discuss