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Sustainable Development of

Underground Space and the

Reuse of Existing Foundations

Global Managing

Consultant

Dr Fiona Chow,

WorleyParsons

Consulting Practices

Themes

Cities of Tomorrow

Land-use

Utilisation of Underground Space

Thermal energy storage

Reuse of existing foundations

Themes

Cities of Tomorrow

Land-use

Utilisation of Underground Space

Thermal energy storage

Reuse of existing foundations

Cities of Tomorrow

History:

Year 1800: 3% of the world’s

population in cities

Year 2000: 47%

Year 2010: 3.2 billion people

Year 2030: 60%, nearly 5 billion

people (UN)

Dramatic increase in developing

countries

Australia’s population is

concentrated in cities

Rank Megacity Country Continent Population Annual Growth

1 Tokyo Japan Asia 34,000,000 0.60%

2 Seoul South Korea Asia 24,200,000 1.40%

3 Mexico City Mexico North America

23,400,000 2.00%

4 Delhi India Asia 23,200,000 4.60%

5 Mumbai India Asia 22,800,000 2.90%

6 New York City

USA North America

22,200,000 0.30%

7 São Paulo Brazil South America

20,900,000 1.40%

8 Manila Philippines Asia 19,600,000 2.50%

9 Shanghai China Asia 18,400,000 2.20%

10 Los Angeles USA North America

17,900,000 1.10%

11 Osaka Japan Asia 16,800,000 0.15%

12 Kolkata India Asia 16,300,000 2.00%

13 Karachi Pakistan Asia 16,200,000 4.90%

14 Jakarta Indonesia Asia 15,400,000 2.00%

15 Cairo Egypt Africa 15,200,000 2.60%

16 Moscow Russia Europe 13,600,000 0.20%

16 Beijing China Asia 13,600,000 2.70%

16 Dhaka Bangladesh Asia 13,600,000 4.10%

19 Buenos Aires

Argentina South America

13,300,000 1.00%

20 Istanbul Turkey Europe & Asia

12,800,000 2.80%

21 Tehran Iran Asia 12,800,000 2.60%

22 Rio de Janeiro

Brazil South America

12,600,000 1.00%

23 London United

Kingdom Europe 12,400,000 0.70%

24 Lagos Nigeria Africa 11,800,000 3.20%

25 Paris France Europe 10,400,000 1.90%

Demands:

for more housing

for the development of marginal land

for the redevelopment of “brownfield” sites

as opposed to “greenfield” sites

more infrastructure

more transport

more construction materials

greater energy supply

greater water supply

greater waste disposal

protection of green areas

Role of the Geotechnical Engineer

We have a major part to play in shaping the environment and

creating better places in which to live

We need to be involved at an early stage of the planning process in

order to mitigate against hazards and reduce construction costs

We need to be able to communicate within a multidisciplinary project

team and influence planners and developers

What can go wrong - Subsidence due to natural cavities in chalk, Norwich, UK

What can go wrong

Slope failure, Hong Kong

1972 Po Shan landslide claiming 67 lives

1977 HK Geotechnical Engineering Office started

Themes

Cities of Tomorrow

Land-use

Utilisation of Underground Space

Thermal energy storage

Reuse of existing foundations

Channel Tunnel Rail Link, UK

Geotechnical engineers had a major

part in planning the route

Reducing development costs: Pikku-Huopalahti, Helsinki

26 ha site reclaimed

from estuary

Housing for 8000

people

€27 million ground

preparation cost

passed to developer

Costs of ground improvement

Method of ground improvement Cost per m2 Relative cost

Pre-loading and vertical drainage €40 1.0

Deep mixing €90 2.25

Piling €160 4.0

Early involvement of the geotechnical engineer allowed

pre-loading and vertical drainage to be used across much

of the site, with large cost savings

Riverside / Waterbank, Perth CBD

Themes

Cities of Tomorrow

Land-use

Utilisation of Underground Space

Thermal energy storage

Reuse of existing foundations

Utilisation of Underground Space

Hidden benefits:

Efficient land use

Improvement of the surface environment

Aesthetics

Conservation and storage of energy

Protection of people against extremes of weather

Security

The Louvre, Paris

Above ground

Below ground

Underground cities - Montreal

The world’s largest underground city

31km passageways

10 metro stations, railway station, bus terminal

1600 shops

200 restaurants

40 banks

30 cinemas

Offices

Swimming pools

Theatres

Protecting citizens from snow, rain and heat and providing an environment free from road accidents

Boston Big Dig: Before

Boston Big Dig: After

Underground Car Parks in Paris

Before After

Viikinmaki wastewater treatment plant Helsinki

SMART project: Kuala Lumpur

Stormwater Management and

Road Tunnel

Motorway tunnel also used for

flood discharge

3 million m3 total storage

capacity

Perth New MetroRail project

Sinking of the Fremantle rail lines, Perth

Existing Planned

Cut-and-cover tunnels over bored tunnels

Tunnel Proximity Study

Numerical modelling

Helsinki Geotechnical Database

Created in 1956

Contains info from over 200,000 boreholes and 40,000 groundwater

monitoring points

Details of building foundations and tunnels

Geographical Information System (GIS) computer format

Accessible to the public for small fee

Statutory requirement to supply information

Helsinki Space Allocation Plan

Completed tunnels - blue

Planned tunnels - red

Helsinki Utility Tunnels

Helsinki Utility Tunnels

Stoke-on-Trent Ground Stability Map

Landslips with pre-

existing shear zones

Slopes steeper than 11

degrees

Backfilled quarries and

backfilled opencast

sites with potential for

large differential

settlements

Valley Alluvium

including clay and peat

Australian flood-hazard

mapping for homes &

basements?

Perth Borehole Database 2001

Transfer of data in AGS RTA format

UK’s Association of Geotechnical & Geoenvironmental specialists

(AGS) standard format for data transfer

1st Edition in 1992, currently AGS 4:

Borehole & test pit logs

CPT and in situ test data

Laboratory test data

ASCII format to feed into any borehole database (e.g. gINT, Holebase etc)

Allows easy transfer of information between different parties: SI

contractors, laboratories, consultants, owners, designers, construction

companies etc

Avoids inefficiencies and errors in re-inputting data

NSW Roads and Traffic Authority produced an Australian version AGS

3.1 RTA 1.1 in 2007 (“AGS RTA format”)

Themes

Cities of Tomorrow

Land-use

Utilisation of Underground Space

Thermal energy storage

Reuse of existing foundations

Scandinavian Airlines HQ, Stockholm

Building has a floor area of 64,000m2

Uses an underground aquifer to store thermal energy

Average ground temperature is 7 to 8°C

Uses five wells with heat exchangers

Two warm wells up to 15°C

Three are cold down to 2°C

During Summer building is cooled

During Winter building is heated

65% energy saving

€55,000

Keble College, Oxford, UK

Energy piles reduce energy costs by 66%

Dornbirn Ice Rink, Austria

320 No. 900mm 18m long piles

800 kW of excess heat from the ice-

making equipment stored in a ground

volume of 100,000 m3 beneath the ice

rink

This energy can be recovered for

heating adjacent buildings which form

part of the complex

WA thermal bores:

Challenge stadium

Craigie recreational centre

Christchurch Grammar

Claremont

St Hilda’s

Themes

Cities of Tomorrow

Land-use

Utilisation of Underground Space

Thermal energy storage

Reuse of existing foundations

Why reuse?

City buildings have a typical life of 40

yrs

Cost of removing a pile in London

ranges between two to five times the

cost of a new pile.

CO2 and sustainability

Uncoordinated underground

proliferation can lead to

ground congestion

increases in the cost of future

redevelopment and

reductions in the value of city sites

Would you reuse this pile?

Why reuse?

Rose Theatre London

Where some of Shakespere’s

plays were first performed

1994 – Pile Testing in Dunkirk, France

Driven pipe piles (324mm dia) installed by CLAROM in 1989

Retested in 1994 by Imperial College (PhD research)

Static load tests in tension

Very dense to dense silica sand, free-draining

Doubling of shaft capacity over 5 years

CLAROM tests

IC tests

1996 Database

Case history data showing pile set-up:

steel, concrete & timber

displacement piles;

sand sites worldwide;

above & below water table;

first-time and re-tests.

A tentative trendline was established

(Chow et al. Geotechnique, 1997)

Pile capacity vs time - original database

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

0.1 1 10 100 1000 10000

Time after EOID (days)

Qt/Q

t(E

OID

)

Implications:

Testing of piles after 20 days

Old piles may be better than young piles

Install piles early & allow increases in capacity with time giving cost savings

1996 - Leman BD Platform, North Sea

Re-evaluation of pile capacities for higher topside loads

Use of the ICP pile design method to show that higher pile capacities

were possible c.f. API predictions

Pile ageing effects gave an additional margin of safety

Case History 1 Empress State Building, London

Constructed 1959-1960

28 stories

Redeveloped 2003

31 stories + 6m extension

Original under-reamed piles

Shaft diameter up to 2.13m

Base diameter up to 3.05m

24m deep in London Clay

No pile test results archived

40 year load test

Empress State Building, London

Column loads increased by 33%

New foundation system:

Limit loads on existing piles

Install new straight-shafted piles

Stiff load transfer structure

FE analysis for pile-pile interaction

Iterative calculations to examine pile

load distribution under different load

cases and stiffness scenarios

Installation of 1.2m diameter

straight-shafted bored piles

St John & Chow, 2006

Case History 2 Juxon House, St Paul’s, London

Original building:

1960’s construction

10 stories

Single level basement

BGS database:

16 boreholes in 1963

New investigation

8 boreholes in 2000

Archaeology

5 test pits to confirm

existing foundations

New development:

Demolish & reconstruct

St John & Chow, 2006

Piling layout

Constraints to development:

Lack of underground space

Cost of removing old piles

Archaeology

Fill over thin Terrace Gravel making raft

foundations problematic

As-built locations

Original under-reamed piles:

Shaft diameter 0.6 to 1.27m

Base diameter 1.52 to 3.20m

13m deep in London Clay

Construction problems

Ground conditions encountered

Scour hole:

Water bearing silt and sand layers

Disturbed London Clay

Detailed pile logs

Verification

As-built construction records

Materials check

All re-used piles were inspected &

integrity tested

Petrographic testing of concrete

Testing of groundwater samples

35 to 45 MPa concrete

Max depth of deterioration = 26mm

Assumed 65mm deterioration

including future design life

Does this affect capacity? Research at

Imperial College suggests not

Load take-down of existing building

confirming design loads

Assessment of pile capacity

Under-reamed piles were designed in

end bearing only

Assessment of pile stiffness

Under-reamed pile at Belgrave House

Piling layout

New CFA and bored piles

Design of a composite old and new pile system taking into account

interaction between the two pile types

More case histories

RuFUS Conference:

“Reuse of Foundations for Urban Sites”

October 2006: BRE UK

39 papers on foundation reuse from

− UK, Ireland, Netherlands, Germany, Greece, Sweden

New York

Guidelines written into the City Building Code

Perth

Reuse of shallow foundations – Condor Tower

Planning for the future

Rethinking foundation design life:

100 years = 2 to 3 generations of buildings

Planning foundation dimensions and layouts:

Small number of large piles allows space for future

piles

Large number of small piles “sterilises” the ground

creating obstructions to future foundation

construction

Collection and storage of design and construction

records:

These could be highly valuable ($$$) in the future

Importance of as-builts and close-out reports

Use of information technology

Electronic information storage

Centralised GIS databases

Cities of tomorrow – value of space

Role of the Geotechnical Engineer

Safe design

Cost effective design

Future-proofed design

Benefits of underground

construction

Need for space planning

Simple Geology for Planners &

Developers

Borehole databases

Transfer of data in AGS-RTA format

Thermal energy storage

Re-use of foundations

SUMMARY