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