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
© Geothermal International
• Introduction – Tony Amis• Structural Perspective - Sam Wong• Designing the Energy Wall – Chris Robinson• Designing the Geothermal solution – Tony Amis• Installing Geothermal Loops – Tony Amis
© Geothermal International
INTEGRATING GEOTHERMAL LOOPS INTO THE DIAPHRAGM WALLS
OF THEKNIGHTSBRIDGE PALACE HOTEL PROJECT
Introduction - Tony Amis
© Geothermal International
Geothermal Solutions
© Geothermal International
© Geothermal International
EnergyPiles® Installed in the UK to Date
Energy Walls ®
© Geothermal International
Energy Walls ®
© Geothermal International
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
© Geothermal International
Knightsbridge Palace Hotel First Energy Diaphragm Wall Project in UK
© Geothermal International
• 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: [email protected] +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
© Geothermal International
Knightsbridge Palace Hotel
36
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
37
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
38
Diaphragm Energy Wall® Construction
Conventional construction
Hydraulic grab – crane mounted
Panels excavated under bentonite support fluid
39
Pile and Diaphragm Energy Wall® Layout
40
Diaphragm Energy Wall® Panel Layout
199 Knightsbridge
Knightsbridge Palace Hotel
41
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
42
Cage and loop installation
43
Rebar cage detailing with loops
44
FF Cover Increase – Rebar Requirements
45
Cage detailing to maintain quality
Designing The Geothermal Solution
Tony Amis Geothermal International
© Geothermal International
Knightsbridge Palace Hotel First Energy Diaphragm Wall Project in UK
© Geothermal International
• 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
© Geothermal International
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?
© Geothermal International
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
© Geothermal International
What conductivity values should be used in ground loop design?
© Geothermal International
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
© Geothermal International
Stage 2: Undertake conductivity test prior to excavation – February 2010
© Geothermal International
Diaphragm wall
Geothermal Loop
Stage 3: Undertake second conductivity test once excavation complete – December 2010
© Geothermal International
Basement
Energy Diaphragm wall / Pile
One side of wall exposed
Geothermal Loop
wall completely buried
Stage 4: Report Results 2011
© Geothermal International
Installation of Geothermal Loops
Tony Amis Geothermal International
© Geothermal International
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
© Geothermal International
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
© Geothermal International
Thanks For Listening
For More Information on Ground sourced heating and Cooling Systems Contact
Tony Amis at [email protected] T: 0247 6673131
Chris Robinson at [email protected] T: 01302 821114 Dr. Sam Wong at [email protected] T 0207 314 4647
© Geothermal International