07.site preparation.civil


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07.site preparation.civil

  1. 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 LtdUNRESTRICTED / ILLIMITÉ
  2. 2. Overall Project ScheduleUNRESTRICTED / ILLIMITÉ 2
  3. 3. Construction ScheduleUNRESTRICTED / ILLIMITÉ 3
  4. 4. Site PreparationUNRESTRICTED / ILLIMITÉ 4
  5. 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 modulesUNRESTRICTED / ILLIMITÉ 5
  6. 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 developmentUNRESTRICTED / ILLIMITÉ 6
  7. 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 planUNRESTRICTED / ILLIMITÉ 7
  8. 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 listsUNRESTRICTED / ILLIMITÉ 8
  9. 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 systemsUNRESTRICTED / ILLIMITÉ 9
  10. 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) )UNRESTRICTED / ILLIMITÉ 10
  11. 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.UNRESTRICTED / ILLIMITÉ 11
  12. 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 pathUNRESTRICTED / ILLIMITÉ 12
  13. 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 gUNRESTRICTED / ILLIMITÉ 13
  14. 14. Main Construction Facilities cont’d. • Mechanical/Piping: – Pipe fabrication shop – Pickle bath facility – Paint shop – Contractor building – Warehouse – Housing for staffUNRESTRICTED / ILLIMITÉ 14
  15. 15. Main Construction Facilities, cont’d. • Electrical, Control and Instrumentation: – Electrical cabling shop – Instrument calibration shop – Contractor building – Warehouse – Housing for staffUNRESTRICTED / ILLIMITÉ 15
  16. 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,UNRESTRICTED / ILLIMITÉ 16
  17. 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 stationUNRESTRICTED / ILLIMITÉ 17
  18. 18. Construction Technologies for Civil and Structural WorksUNRESTRICTED / ILLIMITÉ 18
  19. 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 criticalUNRESTRICTED / ILLIMITÉ 19
  20. 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 constructionUNRESTRICTED / ILLIMITÉ 20
  21. 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 facilitiesUNRESTRICTED / ILLIMITÉ 21
  22. 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.UNRESTRICTED / ILLIMITÉ 22
  23. 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.UNRESTRICTED / ILLIMITÉ 23
  24. 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 gUNRESTRICTED / ILLIMITÉ 24
  25. 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 buildingsUNRESTRICTED / ILLIMITÉ 25
  26. 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.UNRESTRICTED / ILLIMITÉ 26
  27. 27. Concrete Placement Methods • Conventional placement method: – Use of buckets and tower cranes to place concrete • Advanced Concrete Placement Method: – Concrete placed with pumpsUNRESTRICTED / ILLIMITÉ 27
  28. 28. Bonding Between Concrete Pours • Conventional method: – Expose aggregates to receive the next pour • Advanced method: – Green cuttingUNRESTRICTED / ILLIMITÉ 28
  29. 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 modulesUNRESTRICTED / ILLIMITÉ 29
  30. 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 plateUNRESTRICTED / ILLIMITÉ 30
  31. 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 steelUNRESTRICTED / ILLIMITÉ 31
  32. 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 eventsUNRESTRICTED / ILLIMITÉ 32
  33. 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 formworkUNRESTRICTED / ILLIMITÉ 33
  34. 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.UNRESTRICTED / ILLIMITÉ 34
  35. 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 pUNRESTRICTED / ILLIMITÉ 35
  36. 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 connectionsUNRESTRICTED / ILLIMITÉ 36
  37. 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 boltsUNRESTRICTED / ILLIMITÉ 37
  38. 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 materialUNRESTRICTED / ILLIMITÉ 38
  39. 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 dUNRESTRICTED / ILLIMITÉ 39
  40. 40. Yard Services • Storm water drainage system • Sewage system • Plant system, piping and cables • Plant roads • Conventional method: – Backfilled trenches • Advanced method – TunnelsUNRESTRICTED / ILLIMITÉ 40
  41. 41. Construction Technologies for Nuclear Power Plant BuildingsUNRESTRICTED / ILLIMITÉ 41
  42. 42. CONTAINMENT BUILDING • Foundation base slab + steel liner • Containment vessel or steel lined concrete • Containment wall + dome • Shield wall (in double containments) • Internal structuresUNRESTRICTED / ILLIMITÉ 42
  43. 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 plantsUNRESTRICTED / ILLIMITÉ 43
  45. 45. Example of RB Base Slab Rebar MatUNRESTRICTED / ILLIMITÉ 45
  46. 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 formworkUNRESTRICTED / ILLIMITÉ 46
  47. 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 timesUNRESTRICTED / ILLIMITÉ 47
  52. 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 modulesUNRESTRICTED / ILLIMITÉ 52
  53. 53. Jump FormingUNRESTRICTED / ILLIMITÉ 53
  54. 54. Jump Forming in Parallel with Liner Construction and InstallationUNRESTRICTED / ILLIMITÉ 54
  55. 55. Jump Forming and Prefab Rebar MatUNRESTRICTED / ILLIMITÉ 55
  56. 56. Completion of Jump FormingUNRESTRICTED / ILLIMITÉ 56
  57. 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 modulesUNRESTRICTED / ILLIMITÉ 57
  59. 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 craneUNRESTRICTED / ILLIMITÉ 59
  60. 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);UNRESTRICTED / ILLIMITÉ 60
  61. 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. craneUNRESTRICTED / ILLIMITÉ 61
  62. 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 craneUNRESTRICTED / ILLIMITÉ 62
  63. 63. Turbine Building ExcavationUNRESTRICTED / ILLIMITÉ 63
  65. 65. Turbine Building ConstructionUNRESTRICTED / ILLIMITÉ 65
  66. 66. Turbine Building Base MatUNRESTRICTED / ILLIMITÉ 66
  68. 68. Prefabricated Rebar MatUNRESTRICTED / ILLIMITÉ 68
  69. 69. Wall Rebar MatUNRESTRICTED / ILLIMITÉ 69