Breakwaters and closure dams 13

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  • 1. Chapter 13: Construction methods forgranular materialct5308 Breakwaters and Closure DamsH.J. VerhagenApril 12, 2012 1Faculty of Civil Engineering and GeosciencesVermelding onderdeel organisatieSection Hydraulic Engineering
  • 2. Elements to consider• Bed fixation or bed protection mattresses, etc.• Shore connected and intermediate dam sections sand fill/quarry; execution• Abutments sheetpile, caisson• Breakwater core; dumped sills• Cover layer, armourApril 12, 2012 2
  • 3. Scour prevention• Change of flow in course of time• Flow distribution over the vertical• Flow is not saturated with sediment• Turbulence intensity increasesApril 12, 2012 3
  • 4. development of a scour holeApril 12, 2012 4
  • 5. lengthApril 12, 2012 5
  • 6. balance of materialApril 12, 2012 6
  • 7. effective scour timeApril 12, 2012 7
  • 8. development of a scour holeApril 12, 2012 8
  • 9. mattresses or granular filters•limited construction height •self healing after minor damage•applicable on steep slopes •absence of structural joints•difficult to remove •simple to remove by dredging•presence of structural joints •no sudden change at the end;•vulnerable to mechanical they can fade out graduallydamage •absence of structural coherence•restricted lifetime •disintegration on steep slopes •considerable construction heightApril 12, 2012 9
  • 10. stability downstream of a sill uc uniform flow Kv = uc withload increaseApril 12, 2012 10
  • 11. Shields with corrections 2 2 Kv uc d= Ks Ψc ΔC 2 Kv − 1 In Cress : Kt = +1 0.4 Rectangular Abutments: Kv = 1.7 => Kt= 2.75April 12, 2012 11
  • 12. example bed protection• Bs = 2.5 * 20 = 50 km2• depth = 10 m• B = 500 m• tidal difference = 3 mApril 12, 2012 12
  • 13. Bed protection in case of horizontalclosure width u0 (max) D (cm) W(kg) 500 2,13 5 0 80/200 450 2,35 6 0 80/200 400 2,60 8 1 80/200 350 2,90 11 2 80/200 300 3,26 17 7 80/200 250 3,68 23 20 10/60 200 4,16 35 65 60/300 150 4,63 50 192 60/300 100 5,13 71 653 300/1000 50 5,47 90 1161 1/3 25 5,68 105 1794 1/3 10 6,27 158 6166 specialApril 12, 2012 13
  • 14. Mixing layers (from ct4310) 5° 10°April 12, 2012 14
  • 15. Jet equations (from ct4310) ⎛ ⎛ z⎞ ⎞ 2 ⎜ − 0.693 ⎜ ⎟ ⎟ 3.5 u0 ⎜ ⎝ ⎝b⎠ ⎟ ⎠ Plane jets : um = b = 0.1 x u = um e x B ⎛ ⎛ R⎞ ⎞ 2 ⎜ − 0.693 ⎜ ⎟ ⎟ 6.3 u0 ⎜ ⎝ ⎝b⎠ ⎟ ⎠Circular jets : um = b = 0.1 x u = um e x D x = distance from sill B = width of gapApril 12, 2012 15
  • 16. Bed protection in case of vertical closure depth U0 u2 3*U2 D (cm) W(kg) 10 2.13 2.13 2.13 5 0 80/200 9 2.36 2.15 2.36 6 0 80/200 8 2.64 2.18 2.64 8 1 80/200 7 2.97 2.20 2.97 14 4 80/200 6 3.38 2.20 3.38 21 14 10/60 5 3.86 2.18 3.86 27 32 10/60 4 4.33 2.07 4.33 39 97 60/300 3 4.63 1.81 4.63 50 192 60/300 2 4.64 1.41 4.24 37 79 60/300 1 3.42 0.74 2.23 5 0 0 3.13 0.41 1.22 1 0 Conclusion: everywhere 60/300 is needed April 12, 2012 16
  • 17. providing quarry material• by road• by rail• by water• a combinationApril 12, 2012 17
  • 18. subsequent working frontsApril 12, 2012 18
  • 19. Construction phases of the ZeebruggeBreakwater (1) Unsustainable material in the location of the breakwater is removed by sea going cutter suction dredgeApril 12, 2012 19
  • 20. Construction phases of the ZeebruggeBreakwater (2) Split-hopper replaces material with sea sand and sea gravelApril 12, 2012 20
  • 21. Construction phases of the ZeebruggeBreakwater (3) Willow mattresses are sunk with two sink pontoons and specialised stone bargesApril 12, 2012 21
  • 22. Construction phases of the ZeebruggeBreakwater (4) Lateral berms are constructed with quarried stones of 3-6 tons with specialised stone bargesApril 12, 2012 22
  • 23. Construction phases of the ZeebruggeBreakwater (5) The dam core is built with quarry stone using heavy duty earth moving equipmentApril 12, 2012 23
  • 24. Construction phases of the ZeebruggeBreakwater (6) The stones are faces with a layer of 1-3 tons stones plus filter construction with Poclain 600April 12, 2012 24
  • 25. Construction phases of the ZeebruggeBreakwater (7) The seaward side is protected by 25-30 ton concrete blocks with an American Hoist 11-310April 12, 2012 25
  • 26. Construction phases of the ZeebruggeBreakwater (8) Finishing: crown block, service road, lightingApril 12, 2012 26
  • 27. a breakwater under constructionApril 12, 2012 27
  • 28. trucks waiting on the breakwaterApril 12, 2012 28
  • 29. use of cheap local equipmentApril 12, 2012 29
  • 30. build up of profiles line dump horizontal layersApril 12, 2012 30
  • 31. use of waterborne and land based equipmentApril 12, 2012 31
  • 32. land based equipmentApril 12, 2012 32
  • 33. tipper truck vs. dump truckApril 12, 2012 33
  • 34. space requirements for heavyequipmentApril 12, 2012 34
  • 35. lifting capacity of acraneApril 12, 2012 35
  • 36. grab typesApril 12, 2012 36
  • 37. Waterborne equipment • Bulk • Pipeline • Floating • flat deck barges • bottom door barges • split barges • tilt barges • side unloading vessels • Individual placementApril 12, 2012 37
  • 38. closure by pumping sandApril 12, 2012 38
  • 39. barges for dumping materialApril 12, 2012 39
  • 40. example of combined transport and crane vesselApril 12, 2012 40
  • 41. motion of a driven wheelApril 12, 2012 41
  • 42. temporary road on soft subsoilApril 12, 2012 42
  • 43. final closure with sand onlyApril 12, 2012 43
  • 44. closure with a cable carApril 12, 2012 44
  • 45. varying construction sequenceApril 12, 2012 45