1. Construction Technologies
related to Site Preparation
Preparation,
Civil and Structural Works
IAEA Construction Technologies Workshop
Constr ction Workshop,
Charlotte NC, August 19-20, 2010
Azhar Khan
Manager, EC6 Plant Layout,
g , y ,
Containment Design and
Constructability,
Atomic Energy of Canada Ltd
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2. Overall Project Schedule
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3. Construction Schedule
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4. Site Preparation
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5. Background to Site Planning and Development
• Phases of site planning and development works:
– Advanced site development
p
– Supply-chain infrastructure
– Off-site management for module fabrication
– Module delivery, assembly and outfitting
– Power island construction
– Open top construction:
– Need at least 1 VHL crane
– M d l i ti and prefabrication:
Modularization d f b i ti
– Fully developed site infrastructure to support offloading , assembly and
outfitting to exact standards before first nuclear concrete.
– Module lay-down areas to be “hardstand”, fully trafficable and heavy
y , y y
load capable.
– Support facilities required for off site module fabrication and module
assembly
– Large area needed for storage, prefabrication and pre assembly of
storage pre-assembly
modules
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6. Site Development Schedule
• Site development affects construction schedule:
– If lay-down areas are not available for storage, prefabrication
and pre-assembly of modules - site construction schedule will
be affected
– Excavation of power block to be completed before site
development
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7. Pre-requisites for Site development and Plant
Construction
• It is recommended that the following be completed prior to
commencement of site development and plant construction:
– Subsurface (soils and bedrock) testing and analysis to assess site
optimum location
– Environmental assessment
– Site survey, and site survey control programme established
– Transportation study for modules, equipment and personnel
– Upgrades and load testing of routes required to handle heavy loads of
existing roads, bridges or overpasses and barge offload facilities
– Significant cuts and fills necessary to provide a flat and level site free of
encumbrances and obstructions
– Design for both permanent and temporary construction facilities
– Electronic three dimensional (3-D) model for all permanent and
temporary sites, structures and components
– Site drainage, trenching for utilities
– Site development schedule
– Excavation plan
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8. Pre-requisites for Site development and Plant
Construction, cont’d.
– Temporary services facilities and assembly areas
– Site development permits, licensing documentation for site
preparation and construction licenses
– Procurement of equipment and facilities required for site
preparation
– Develop quality assurance program
– Quality Assurrance procedures
– Quality surveillance procedures/check lists
– Quality control procedures/check lists
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9. Methods Utilized for Site Infrastructure Implementation
and Layout for Site Construction
• All weather construction method:
– Construction environment isolated from ambient weather
– Buildings have temporary enclosures – Qinshan CANDU
– Open top Construction
• Methods for construction personnel mobility:
– Scaffolding
– Mobile scissor lifts, bucket trucks
– Access to personal services (tool sheds, toilets, wash water)
– Mobile communication systems
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10. Methods Utilized for Site Infrastructure Implementation
and Layout for Site Construction, cont’d.
• Transportation:
– Stick build approach
– Modularization approach
– Combined approach
– Heavy haul path
– Need barge unloading facility and heavy haul road(s)
– Railroads
• Site mapping and measuring:
– Existing conditions including topography
– Existing buildings and infrastructure
– Existing underground infrastructure
– Layout of reference points and markers
– Laser and global p
g positioning system mapping (
g y pp g (GPS)
)
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11. Methods Utilized for Site Infrastructure Implementation
and Layout for Site Construction, cont’d.
• Three dimensional modeling:
– It can be developed during early design stages so that the entire
plant can be designed using available software
– There would be cases where the vendor already has a design with
approved two dimensional (2-D) drawings that need to be partially
modified to account for country specific requirements.
– In such cases, it is recommended that the design drawings are input
to the 3-D modelling software to derive the required modifications.
– The only disadvantage in using 3-D modelling is that considerable
time is needed to develop interference-free plant layout, to work out
the BOM to be procured, and to develop ‘working drawings’ to be
used in the field.
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12. Main Construction Facilities
• Construction management centre:
– Use the latest technology to provide direction and control of real time
field activities, tracking of equipment, visual and daily debriefing with
field personnel
– Video conferencing
– Real time management of critical path
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13. Main Construction Facilities, cont’d.
• Civil:
– Computerized concrete batch plants:
– Good quality concrete on a continuous basis with no human error
– Concrete/materials testing laboratories
– Embedded parts fabrication shop
– Reinforcing steel fabrication shop
– Shop fabrication mock-up:
– F ll scale or partial scale mock-ups can save on actual work ti
Full l ti l l k t l k time
– Structural steel fabrication/assembly shop
– Paint shop
– Contractor building
– Warehouse
– Housing for staff
g
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14. Main Construction Facilities cont’d.
• Mechanical/Piping:
– Pipe fabrication shop
– Pickle bath facility
– Paint shop
– Contractor building
– Warehouse
– Housing for staff
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15. Main Construction Facilities, cont’d.
• Electrical, Control and Instrumentation:
– Electrical cabling shop
– Instrument calibration shop
– Contractor building
– Warehouse
– Housing for staff
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16. Main Construction Facilities, cont’d.
• Owner:
– Material management centre
– Technical and administration building
– Lay-down and assembly areas(modules, liner vessels,
equipment)
– Warehouse
– Housing for staff
– Transportation depot
– VHL crane
– Tower c a es and te escop c c a es
o e cranes a d telescopic cranes
– Construction control room
– Construction parking
– Security fencing gates and building
fencing,
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17. Main Construction Facilities, cont’d.
• Owner cont’d.:
– Temporary power
– Fire protection water and service water
– Housing for staff
– Transportation depot
– Cafeteria for workers
– First aid station
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18. Construction Technologies for Civil
and Structural Works
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19. Civil and Structural Works
• Civil and structural works comprise the construction (fabrication,
manufacture) of buildings, structures and their components and
the supply of yard services (drainage, fencing, etc.)
• Longest duration on project schedule
• Hence important to optimize by using advanced methods that
reduce the schedule
• Very difficult and very time consuming to correct mistakes
– Quality assurance program is critical
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20. Civil and Structural Works cont’d.
• The civil and structural works comprise the following:
– Site clearing, grading and surveying;
– Site protection works against flooding, tidal waves, typhoon, tsunami, etc.;
– Excavation;
– Earth soil/rock removal and disposal;
– Site dewatering;
– Remedial measures on foundation soil/rock;
– Rock and soil slope stabilization;
– Building under drainage;
– Foundation works;
– Building peripheral drainage;
– Concrete works abo e foundation;
Co c e e o s above ou da o ;
– Structural steel fabrication and erection
– Yard services
– Backfill works
– Roads and landscaping
– Permanent security construction
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21. Excavation
• Requires permits from local jurisdiction prior to start
• Requires construction license from regulator prior to start in some
countries
• Activity of long duration that can last between 6 to 12 months
• Sometimes adjacent to operating nuclear power plants
• Environment regulations and constraints
• It is essential to minimize damage to final foundation material:
Protection from blasting near final level
• Protection from flood and freezing
• It is essential to provide protection to workers
• It is essential to provide protection to nearby facilities
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22. Excavation Cont’d.
• Conventional method:
– Uses light machinery, blasting and hand excavation
machinery excavation.
• Advance method:
– Precision line blasting;
– Chemical foam expansion for breaking rock.
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23. Confirmation Of Soundness Of
Foundation Materials And Remedial
Measures
• Visual examination
– Identification of weak areas
• Open pit load tests to confirm foundation materials
• Conventional remedial measures:
– Extra excavation to overcome weak areas;
– Thicken and/or enlarged sub-base engineered to reduce differential
settlement and tilt of buildings.
• Advanced method:
– Consolidation grouting;
– Rock anchors;
– Bridging of weak areas;
– Instrumentation to measure differential settlement and tilt of
buildings.
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24. Remedial Measures For Slope
stabilization
Objective:
– Safety of workers equipment and project assets during the
workers,
construction phase
Conventional methods:
– Reducing slope of cuts
– Use of anchored steel mesh
• Advanced methods
– Consolidation Grouting
– Grouted rock anchors
– Earth reinforcing
at e oc g
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25. Concrete Types
• Responsibility of site engineering to develop the specified mix designs
• Nuclear plants are using more concrete; Hundred of thousands of cubic meters
• Functional & performance requirements of buildings are different hence it is
economical to specify different mixes
• Concrete mixes should be developed and approved at least 6 months before
concreting program
• Supply of constituent materials (aggregates, sand, water, fly ash, etc) must be
confirmed a minimum of 12 months before start of concreting program
• Portland cement is normally used
• Heavy shielding concrete
• Higher performance concretes (45-60 MPa) are being specified recently for
containment buildings
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26. CONCRETE TYPES cont’d.
• Conventional Concrete Mixes
– Portland cement
– 25 to 35 MPa
– Heavy shielding concrete
Advanced Concrete Mixes:
– High workability concrete;
– High performance concrete: 45 to 60 Mpa;
– Fly ash concrete; large volume pours;
– Pervious or “no fine” concrete;
– Pre-cast concrete;
– Self Consolidating Concrete;
Self-Consolidating
– Self levelling concrete.
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27. Concrete Placement Methods
• Conventional placement method:
– Use of buckets and tower cranes to place concrete
• Advanced Concrete Placement Method:
– Concrete placed with pumps
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28. Bonding Between Concrete Pours
• Conventional method:
– Expose aggregates to receive the next pour
• Advanced method:
– Green cutting
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29. Reinforcing Steel
• Conventional reinforcing steel method:
– Placing steel bars with lap splices
– Bar size 44 mm and above are connected by exothermic welding
• Advanced reinforcing steel methods:
– Using mechanical & cad weld splicing
– T-headed shear bars
– Use of automatic rebar tie machines
– Large prefabricated rebar modules
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30. Embedded Parts
• Conventional embedded parts:
– Plate type with manually welded strips or studs for anchoring in
concrete
– Embedded anchor bolts for equipment and structural steel
– Penetrations for piping and conduits
pp g
• Advance embedded parts method:
– Plate type with studs welded with stud gun
– Steel plate reinforced walls: Supports are connected directly
to the plate
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31. Expansion Anchors
• These are anchors drilled into concrete to support structures,
systems and components
• Objective:
– Should reduce the use of expansion anchors to only support conduits and
p y pp
non-seismically qualified systems and non vibrating equipment
– Anchors should not cut reinforcing steel
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32. Foundation Construction
• Conventional foundation construction methods:
– Spread footings, combined footings, mat foundations, pile
foundations
– In the case of mat foundations, multiple pours are used
• Advanced foundation construction methods:
– Advances in concrete technology and placement methods have
– led to single pours for large mats
– Advances in the development of seismic isolations p
p permit the
– isolation of foundations for structures and equipment and thus
– protect them from high seismic events
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33. Concrete Construction Above Foundation
• Formwork
• Conventional formwork:
– Slab formwork consists of wood/metal forms supported by shoring
– Wall formwork consists of wood/metal face forms held together with
form ties
– Forms are stripped after concrete has set and achieved sufficient
strength so that it can support its dead load plus a small live load
• Advanced types of formworks:
– Q-deck or left in shutters
– Steel plate reinforced walls (no reinforcing steel in walls)
– Steel plate modular floors
– Pre-fabricated permanent formwork
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34. Walls & Columns
• Conventional Method:
– Place conventional form and pour concrete through trunks up to
height of 6 to 7 meters.
• Advanced Construction:
– Steel plate reinforced walls;
– Self consolidating concrete;
– Self levelling concrete.
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35. Slab, floors and roofs
• Conventional Method:
– Use conventional concrete mixes conventional reinforcing steel with
mixes,
lap splicing, conventional formwork
Advanced Method:
– Use Q Deck or left in shutters in slabs not supporting seismically
Q-Deck
qualified systems
– Modular floors
– Steel reinforcement concrete composite structures and Deck Plate
construction
– Self compacting concrete
– Pre-fabricated permanent formwork
p
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36. Structural Steel Fabrication
• Braced frames consisting of columns, beams and bracing, and
equipment supporting steel systems
• Conventional method
– Cutting and welding of structural steel based on two-dimensional
fabrication drawings and using manual measurements
– Use of clip angles
– Maximize welding in shop
• Advanced method
– Automated fabricating shop
– Use of 3D and precision control maintained by lasers
– Use of end plate connections
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37. Structural Steel Erection
• Conventional method:
– Use of temporary bracing to align and temporarily support the
braced frame structures
– Use of conventional high strength steel bolts using torque method
such as turn of nut and calibrated wrenches
– Maximize bolting and minimize welding at site
• Advanced method:
– Facilitates modularization and parallel works
– Use of buckling restrained braces (BRBs)
– Use of twist off bolts
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38. Water Proofing
• Required for underground structures, basements, large water
transporting system, liquid retaining concrete tanks, etc.
• Conventional method:
– Use of rubber water-stops
– Use of external painted waterproofing on structures below ground
– Use of sump pump installation
• Advanced method:
– Use of superior waterproofing material with advance spraying
system
– Use of fast setting epoxy injection material
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39. Backfilling
• Used for areas between open cut and buildings;
• Used in pipe trenches
• Used in landscaping
• Conventional method:
– Common backfill in open area
– Granular backfill adjacent to building and covering piping in trenches
• Advanced method:
–CCement / sand backfill mixture i used
t d b kfill i t is d
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40. Yard Services
• Storm water drainage system
• Sewage system
• Plant system, piping and cables
• Plant roads
• Conventional method:
– Backfilled trenches
• Advanced method
– Tunnels
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41. Construction Technologies for
Nuclear Power Plant Buildings
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42. CONTAINMENT BUILDING
• Foundation base slab + steel liner
• Containment vessel or steel lined concrete
• Containment wall + dome
• Shield wall (in double containments)
• Internal structures
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43. FOUNDATION BASE SLAB + LINER
• Large reinforced concrete mat foundations (greater than 5000 m3)
• Waterproofing membrane under foundation
• Conventional Method:
– Multiple pours, placed to minimize shrinkage
–CConventional concrete d i mix
ti l t design i
• Advanced Methods:
– Single pour due to improved concrete technology / concrete mixes
with low shrinkage cement reduced cement content increased use
cement, content,
of plasticizer admixtures, etc.
– Significant increase in concrete pump use
– Increased reliability of batch plants
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44. BASE SLAB
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45. Example of RB Base Slab Rebar Mat
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46. CONTAINMENT WALL
• Conventional Method:
– Use pre-assembled gang wall forms & construct in multiple repetitive
pre assembled
concrete lifts between 6 to 7 meters
– Concrete placement using trunks to pour concrete; not greater than
1 meter fall
– Use vibrators for achieving homogeneity
– Carpenter crews are employed for erecting forms
– Large scaffolding to set up
• Advanced Method:
– Slip-forming:
– Continuous placing of concrete at p p
p g pre-planned rates
– Hydraulic lift with jacks moving short section of formwork
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47. Climbing Formwork
• Climbing formwork is a self supporting
formwork system.
• Standard steel forms supported from
frame
• After wall is poured, form is released and
rolled back from face
• Jacks lift or climb the whole frame up
one level
• Prefab rebar installed
• Formwork panels are closed and next
p
concrete wall is poured
• Standard cycle times
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48. CONTAINMENT WALL SLIP-FORMING cont’d.
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49. CONTAINMENT WALL SLIP-FORMING cont’d.
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50. CONTAINMENT WALL SLIP-FORMING cont’d.
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51. CONTAINMENT WALL SLIP-FORMING cont’d.
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52. CONTAINMENT WALL cont’d.
• Advanced Method cont’d.:
– Jump forming:
– This method is being used to construct practically all steel lined
containment walls
– Wall is formed in stages with the form lifted hydraulically or “jumped
g y y j p
up” to the next stage after concrete has reached sufficient strength
– Use of prefabricated rebar modules
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53. Jump Forming
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54. Jump Forming in Parallel with
Liner Construction and Installation
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55. Jump Forming and Prefab Rebar Mat
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56. Completion of Jump Forming
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57. CONTAINMENT DOME
• Conventional Method:
– Support formwork:
– Uses a space truss system and shoring supports from the
base slab
• Advanced Method:
– Use a permanent steel plate dome formwork, lifted into place with a
VHL crane
– Jump form the dome
– Use of prefabricated rebar modules
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58. CONTAINMENT DOME cont’d.
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59. INTERNAL STRUCTURES
• Conventional Method:
– Use preassembled gang wall forms or hand set forms and construct the wall
in multiple repetitive lifts
– Construction is up to underside of slabs, construct slab and then proceed
with columns and walls up to next slab
– Conventional concrete mixes are used
– Scaffolding is supported from the base slab and subsequently from the next
slab
Advanced Methods:
– Use Q-deck or left in shutters supported by steel beams, for slabs not
supporting seismically qualified systems
– Self consolidating concrete
– Self levelling concrete
– Proposed methods are to use modular floors and modules with mechanical
and electrical systems. These activities are performed off site and
subsequently, the modules are transported to site and installed with a VHL
q y p
crane
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60. TURBINE BUILDING
Significant activities are:
– Excavation (significant at coastal sites with large tidal variations)
– Dewatering system
– Base Slab
– Turbine generator Pedestal
– Structural Steel
– Building Crane (200 tons or greater);
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61. TURBINE BUILDING
Conventional Method:
– Base slab is constructed in multiple pours;
– For concrete structures use preassembled gang wall forms and
construct the wall in multiple repetitive lifts;
– Turbine generator p
g pedestal is concreted similar to other concrete
structures;
– Structural steel is erected with conventional method of erecting
braced frames, stabilizing with temporary or permanent braces
– Roof trusses are installed on columns after being preassembled on
ground;
– Building Crane is lifted in to place with a heavy lift transportation
crane.
crane
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62. TURBINE BUILDING cont’d.
Advanced Method:
– Base slabs – single pour or larger pours
– Concrete structures – left in shutters, pumped concrete
– Turbine pedestal – seismic isolators and self consolidating concrete,
p p
pumped concrete
– Structural Steel – modularized and installed with heavy lift crane,
use of buckling restraint braces, twist off bolts
– Turbine building crane – installed with VHL crane
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63. Turbine Building Excavation
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64. TURBINE BUILDING CONSTRUCTION
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65. Turbine Building Construction
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66. Turbine Building Base Mat
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67. TURBINE BUILDING CONSTRUCTION
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68. Prefabricated Rebar Mat
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69. Wall Rebar Mat
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