Vermelding onderdeel organisatie

February 1, 2012

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Chapter 13: Construction methods for granular material

ct5308 Breakwaters and Closure Dams

H.J. Verhagen

Faculty of Civil Engineering and Geosciences Section Hydraulic Engineering

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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, armour

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Scour prevention

• Change of flow in course of time

• Flow distribution over the vertical

• Flow is not saturated with sediment

• Turbulence intensity increases

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development of a scour hole

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length

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balance of material

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effective scour time

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development of a scour hole

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mattresses or granular filters

•limited construction height

•applicable on steep slopes

•difficult to remove

•presence of structural joints

•vulnerable to mechanical damage

•restricted lifetime

•self healing after minor damage

•absence of structural joints

•simple to remove by dredging

•no sudden change at the end; they can fade out gradually

•absence of structural coherence

•disintegration on steep slopes

•considerable construction height

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stability downstream of a sill

increase load withu

flow uniform u = K

c

cv

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Shields with corrections

2 2

2

1: 1

0.4

v c

s c

vt

K ud

K C

KIn Cress K

Rectangular Abutments: Kv = 1.7 => Kt= 2.75

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example bed protection

• Bs = 2.5 * 20 = 50 km2

• depth = 10 m

• B = 500 m

• tidal difference = 3 m

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Bed protection in case of horizontal closure 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 special

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Mixing layers (from ct4310)

5°

10°

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Jet equations (from ct4310) 2

2

0.693

0

0.693

0

3.50.1

6.30.1

z

b

m m

R

b

m m

uPlane jets : u = b = x u = u e

x B

uCircular jets : u = b = x u = u e

x D

x = distance from sill B = width of gap

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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

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providing quarry material

• by road

• by rail

• by water

• a combination

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subsequent working fronts

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Construction phases of the Zeebrugge Breakwater (1)

Unsustainable material in the location of the

breakwater is removed by sea going cutter suction

dredge

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Construction phases of the Zeebrugge Breakwater (2)

Split-hopper replaces material with sea sand and sea

gravel

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Construction phases of the Zeebrugge Breakwater (3)

Willow mattresses are sunk with two sink pontoons

and specialised stone barges

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Construction phases of the Zeebrugge Breakwater (4)

Lateral berms are constructed with quarried stones of

3-6 tons with specialised stone barges

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Construction phases of the Zeebrugge Breakwater (5)

The dam core is built with quarry stone using heavy

duty earth moving equipment

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Construction phases of the Zeebrugge Breakwater (6)

The stones are faces with a layer of 1-3 tons stones

plus filter construction with Poclain 600

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Construction phases of the Zeebrugge Breakwater (7)

The seaward side is protected by 25-30 ton concrete

blocks with an American Hoist 11-310

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Construction phases of the Zeebrugge Breakwater (8)

Finishing: crown block, service road, lighting

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a breakwater under construction

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trucks waiting on the breakwater

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use of cheap local equipment

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build up of profiles

line dump

horizontal layers

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use of waterborne and land based equipment

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land based equipment

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tipper truck vs. dump truck

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space requirements for heavy equipment

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lifting capacity of a crane

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grab types

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Waterborne equipment

•Bulk

• Pipeline

• Floating

• flat deck barges

• bottom door barges

• split barges

• tilt barges

• side unloading vessels

• Individual placement

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closure by pumping sand

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barges for dumping material

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example of combined transport and crane vessel

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motion of a driven wheel

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temporary road on soft subsoil

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final closure with sand only

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closure with a cable car

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varying construction sequence