GE Presentation 6th October 2010

Basements & Underground Structures Conference

6th October 2010

INTEGRATING GEOTHERMAL LOOPS INTO THE DIAPHRAGM WALLS OF THE

KNIGHTSBRIDGE PALACE HOTEL PROJECT

  Tony Amis, Geothermal International Limited

Christopher A. W. Robinson, Cementation Skanska Ltd

Samuel Wong, WSP Cantor Seinuk

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• Introduction – Tony Amis• Structural Perspective - Sam Wong• Designing the Energy Wall – Chris Robinson• Designing the Geothermal solution – Tony Amis• Installing Geothermal Loops – Tony Amis

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INTEGRATING GEOTHERMAL LOOPS INTO THE DIAPHRAGM WALLS

OF THEKNIGHTSBRIDGE PALACE HOTEL PROJECT

Introduction - Tony Amis

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Geothermal Solutions

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EnergyPiles® Installed in the UK to Date

Energy Walls ®

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Energy Walls ®

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Opportunities For Crossrail

1km of Diaphragm wall or piles - 40m deep could provide..

• 500kW of Peak Heating• 500kW of Peak Cooling• Save 350 tonnes of CO2 per Annum• Reduce Energy Bill by approx £90k per annum when

compared against conventional systems

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Knightsbridge Palace Hotel First Energy Diaphragm Wall Project in UK

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• System:– Diaphragm Wall &

Energy Piles®

• Size:– 150kW Heating– 150kW Cooling

• Collector type:– 50 Energy Piles– 150m Energy D. Wall

• On Site:– D. Wall underway– Piling start Feb 2010

Knightsbridge Palace Knightsbridge Palace HotelHotel

Structural PerspectiveStructural Perspective

Dr. Sam WongBSc PhD FIStructE MICE MASCEContact: sam.wong@wspgroup.comTel +44 207 314 4674

Building dataBuilding data

• 6 basement levels, 22m deep6 basement levels, 22m deep• 1010 storeys above ground storeys above ground• Plain RC and PTPlain RC and PT• Steelwork at G/F to B2 for long span structure (up to 15m) Steelwork at G/F to B2 for long span structure (up to 15m)

over ballroom over ballroom • Major transfer beams at Level 1 and transfer slabs at Major transfer beams at Level 1 and transfer slabs at

upper level set-backs.upper level set-backs.• Incorporating geothermal loops in Diaphragm wall and load Incorporating geothermal loops in Diaphragm wall and load

bearing pilesbearing piles

Bridge over Raphael Bridge over Raphael StreetStreet

Section adjacent to Raphael StreetSection adjacent to Raphael Street

Diaphragm wallgeothermal pipework (Slinky)

Plunge column Plunge column constructionconstruction

Top down construction Top down construction sequencesequence

Stage 1Stage 1

Stage 2Stage 2

Stage 3Stage 3

Stage 4Stage 4

Stage 5Stage 5

Stage 6Stage 6

Stage 7Stage 7

Stage 8Stage 8

Stage 9Stage 9

Stage 10Stage 10

Stage 11Stage 11

Stage 12Stage 12

Stage 13Stage 13

Ground movement assessmentGround movement assessment

Building when completed

Designing The Diaphragm Wall

Chris Robinson Cementation Skanska

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Knightsbridge Palace Hotel

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Scope of geotechnical works

35 No. plunge column Energy Piles®, max. 61.5m deep

15 No. tension piles, max. 47.5m deep

Approx. 155 lin. m 800mm wide Energy Wall® (Diaphragm wall panels with integrated

geothermal loops), max. 36m deep

6 storey basement, max. dig depth 24m

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Ground conditions

General sequence:-

EGL – 9.00m OD Made ground

9.00 – 4.50m OD Firm silty clay

4.50 – -2.00m OD Terrace Gravels

-2.00 – EOH London Clay

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Diaphragm Energy Wall® Construction

Conventional construction

Hydraulic grab – crane mounted

Panels excavated under bentonite support fluid

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Pile and Diaphragm Energy Wall® Layout

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Diaphragm Energy Wall® Panel Layout

199 Knightsbridge

Knightsbridge Palace Hotel

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Principle issues

Attaching loops to D-wall cages

Maintaining integrity of loops

Testing loops during panel construction

Mitigating additional cage congestion

Maintaining high quality construction

Ensure no adverse effect of panel construction programme

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Cage and loop installation

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Rebar cage detailing with loops

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FF Cover Increase – Rebar Requirements

45

Cage detailing to maintain quality

Designing The Geothermal Solution

Tony Amis Geothermal International

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Knightsbridge Palace Hotel First Energy Diaphragm Wall Project in UK

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• System:– Diaphragm Wall &

Energy Piles®

• Size:– 150kW Heating– 150kW Cooling

• Collector type:– 50 Energy Piles– 150m Energy D. Wall

• On Site:– D. Wall underway– Piling start Feb 2010

Knightsbridge Palace Hotel Schematic

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What are the issues with installing loops in wall piles and diaphragm walls

• What are the effects of transferring heat into piles to provide cooling?

• What are the effects of cooling piles to provide heating?

• What are the thermal effects of removing soil from one face to form basement?

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Key Energy Pile® / Wall Research to date

• Brandl 2006 – reported on several projects across Austria concluded that shaft resistance, base pressure and bearing resistance of soil are not affected by heat absorption and that temperature induced settlement or heave negligible

• Laloui 2006 – Identified that the heating-cooling process of the building foundations induces significant modifications in the soil-structure leading to additional stresses in the piles, decrease of the lateral friction and the possibility of a gap between the pile and the soil

• Bourne Webb et al 2009 - temperature change in piles leads to increases and decreases in shaft resistance and axial load. Working stresses in pile should be kept low, and maintain high factor of safety on shaft to withstand heating and cooling loads

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What conductivity values should be used in ground loop design?

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Basement

Energy Diaphragm wall / Pile

One side of wall exposed

Geothermal Loop

wall completely buried

Geothermal International Research & Development at Knightsbridge Palace Hotel

Stage 1: Installation of loops in diaphragm wall - completed

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Stage 2: Undertake conductivity test prior to excavation – February 2010

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Diaphragm wall

Geothermal Loop

Stage 3: Undertake second conductivity test once excavation complete – December 2010

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Basement

Energy Diaphragm wall / Pile

One side of wall exposed

Geothermal Loop

wall completely buried

Stage 4: Report Results 2011

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Installation of Geothermal Loops

Tony Amis Geothermal International

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Pre-installation Quality Control & Testing

Lifting the DWall Cage

Installing the Loops

Installing the Loops

Installing the second cage

Fixing the loops to the cage

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Trimming and Protecting

Pre-concrete Pressure Test

Concreting the DWall

Key Lessons learnt• Ensure early coordination between all parties at all stages of

the project– Design team– Construction team

• Keep it simple – Minimise joints in loops where possible– Prefabricate loops– Pressure test loops at key stages

• Build-ability issues– Good Preparation– Good coordination between Contractors– Avoid men having to place hands in cages

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Thanks For Listening

For More Information on Ground sourced heating and Cooling Systems Contact

Tony Amis at ta@geothermalint.co.uk T: 0247 6673131

Chris Robinson at chris.robinson@skanska.co.uk T: 01302 821114 Dr. Sam Wong at sam.wong@wspgroup.com T 0207 314 4647

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