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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
