construction of breakwaters

8/11/2019 Construction of Breakwaters

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Breakwaters are man made structures

constructed to protect Port and Harbour

structures from fury of ocean waves and

provide tranquil conditions for ships at

berth.


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BREAKWATERPROFILES


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Breakwaters are mainly classified

under the following four groupsdepending upon their type of

construction and sea-ward slope.


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Vertical breakwater - Type V

Composite breakwater - Type C

Special type of breakwaters

Sloping breakwater - Type S


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Sloping breakwater - Type S:

This has a sea-ward sloping face of 1:1 or

flatter.


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Vertical breakwater - Type V:

This has a vertical or near vertical sea-

ward face


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Composite breakwater - TypeC:

This consists of a vertical breakwaterconstructed on a rubble foundation

with slope on both sides.


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Special type of breakwaterssuch as

sub-merged breakwaters,

floating breakwaters,

bubble screen

(compressed air) breakwaters

are used for special applications.


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Typical cross sectionsof the first three types

of breakwaters are shown in the Figure.


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TYPICAL CROSS SECTION OF BREAKWATERS


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Rubble Mound

Conventional multi-layerrubble mound

Multi-layer rubble mound

with superstructure

Berm Breakwater

Reef Breakwater


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TYPES OF RUBBLEMOUND BREAKWATERS

Conventional Rubblemound Breakwater

Toe

Core

LeesideSeaside

Filter

Crest

LWL

HWL


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Berm Breakwater

CORE

CREST

BERM

SEA SIDE LEE SIDE

FILTER

LWL

HWL

N EPT F WIDE T E BERM IN DE I N


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N EPT F WIDE T E-BERM IN DE I N

OF RUBBLEMOUND BREAKWATER

Wide Toe Core

LeesideSeasideCrest

LWL

HWL

Filter

Breakwater with Wide - Toe Berm

+11 m7 m

Lee SideSea Side

20 m0.0 m Core

35 t

- 7 m

Damage Profile

COST COMPARISON


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Net Saving = Rs. 12 Crores

COST COMPARISON

OF CONVENTIONAL & WIDE TOE BERM BREAKWATER

Conventional

1) Tetrapod = 43 T ( 73 Cum / m)@ Rs. 6000/Cum = Rs. 4.38 Lakh / m

2) Toe berm = ( 3-5 t stones)= 181 T/m

@ Rs. 340/ T = Rs. 0.62 Lakh/ Rmt

3) Secondary ( 0.75- 2t stones) = 566 T/m

@ Rs. 340/ T = Rs. 1.92 Lakh / Rmt

4) Core Stones ( 5-500 kg) = 600 T/m

@ Rs. 250/ T = Rs. 1.40 Lakh / m

Total = Rs. 8.32 Lakh / m

Total Cost for 600 m = Rs 49.9 Crore

Wide Toe Berm

1) Tetrapod = 12 T ( 46 Cum / m)@ Rs. 4475/ Cum = Rs. 2.05 Lakh / m

2) 20 m toe berm ( 3-5 t stones)= 275 T/m

@ Rs. 340/ T = Rs. 0.94 Lakh/ Rmt

3) Secondary ( 0.75- 2t stones) = 566 T/m

@ Rs. 340/ T = Rs. 1.92 Lakh / Rmt

4) Core Stones ( 5-500 kg) = 600 T/m

@ Rs. 250/ T = Rs. 1.40 Lakh / m

Total = Rs.6.31 Lakh / m

Rs 37.9 Crore


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Various types of natural rock are

normally used. However, when

sufficiently large blocks are not available

from the quarry or the wave conditions

are very severe at the breakwater

locations, the concrete artificial armour

unitsare used.


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About 40 different types of artificial

armour units have been developed.The important among them are

shown in Figure.

ARTIFICIAL CONCRETE BLOCKS FOR BREAKWATERS


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ARTIFICIAL CONCRETE BLOCKS FOR BREAKWATERS


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BREAKWATER DESIGN FORMULAE


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RUBBLE MOUND BREAKWATER SLOPES

The stability of the Breakwater is

dependent on its slope.

The weight of the armour unit increases

with the steepness in slope.

Generally adopted slopes are 1:1.5 to 1:3


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STABILITY TESTS

Though the cross section of the

breakwater are evolved based on the

Empirical Formulae, it is essential to carry

out a Flume Test with Random Waves.


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MODEL TESTS

Mathematical Model

Physical Model

Wave Basin and

Wave Flume


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OPTIMISATION OF DESIGN OFRUBBLEMOUND BREAKWATERS

Hydraulic Model Studies in Wave Flumes / Basins


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MODES OF FAILURES OF CONVENTIONAL

RUBBLEMOUND BREAKWATER

Slip FailureScour

Berm & Toe

Erosion Filter

InstabilityCore Settlement

Sub Soil Settlement

Erosion, Breakage

of Armour

Overtopping

Breaking, Sliding,

Tilting of CoppingWall

VentingSlip FailureSlip Failure

RUBBLE MOUND BREAKWATERS


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RUBBLE MOUND BREAKWATERSRecommended three layer section

(Shore Protection Manual1984)

VERTICAL BREAKWATERS


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Conventional Caisson Type Breakwater

Conventional Block Type Breakwater

Sloping Top Type Breakwater

VERTICAL BREAKWATERS


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Perforated Wall Type Breakwater

Japanese Type Breakwater

Composite Type Breakwater


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RUBBLE MOUND BREAKWATER

CONSTRUCTION TECHNIQUES


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Land or Marine Haul of Material

Land or Marine Placing of Materials

Construction from Shore outwards and

Construction from offshore towards shore

One or all the above combination may be

required in a particular project.


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Land Based Equipment

Direct Dumping of Material

Dump Trucks

Loaders and

Cranes


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Land Based Equipment

Controlled Placing

Cranes

BREAKWATER CONSTRUCTION


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LAND BASED EQUIPMENT


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DIGITAL CHARACTERIZATION OF THE BLAST FACEBEFORE BLASTING.


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SORTING OF STONES IN QUARRY


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Q

LOADING OF STONES INTO DUMPERS


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TRANSPORT OF STONES FROM

QUARRY TO BREAKWATER

CASTING OF ARTIFICIAL CONCRETE BLOCKS
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CASTING OF ARTIFICIAL CONCRETE BLOCKS

STACKING OF ARTIFICIAL CONCRETE BLOCKS


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STACKING OF ARTIFICIAL CONCRETE BLOCKS


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ARTIFICIAL CONCRETE BLOCKSSTACKYARD

HANDLING OF ARTIFICIAL CONCRETE BLOCKS


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HANDLING OF ARTIFICIAL CONCRETE BLOCKS

HANDLING ATTACHMENT FOR ARTIFICIAL CONCRETE BLOCKS


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HANDLING ATTACHMENT FOR ARTIFICIAL CONCRETE BLOCKS

HANDLING OF ARTIFICIAL CONCRETE BLOCKS IN STACKYARD


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HANDLING OF ARTIFICIAL CONCRETE BLOCKS IN STACKYARD


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PLACING OF ARMOUR STONES


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PLACING OF ARTIFICIAL CONCRETE BLOCKS


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BREAKWATER CONSTRUCTION - LAND BASED TECHNIQUES


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Floating Equipment

Direct Dumping of Material

Split Barges

Bottom Door Barges

Tilting Barges

Floating Equipment


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Floating Equipment

Controlled Placing Side Stone Dumping Vessel

Fall Pipe Vessel

Flat Deck Barges with Bull Dozer

Pontoon with a Crane

BREAKWATER CONSTRUCTIONFLOATING EQUIPMENT


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Q

Split Hopper Barge Dumping through a pipeSide Stone DumpingVessel

CONSTRUCTION - GEOTEXTILE


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CONSTRUCTION - CORE


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CONSTRUCTION CORE

CONSTRUCTION - TOE


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CONSTRUCTION - CORELOC


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VERTICAL BREAKWATER

CONSTRUCTION TECHNIQUES

CAISSON UNDER CONSTRUCTION


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CAISSON BEING TOWED TO POSITION


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CAISSON BEING TOWED TO POSITION

CAISSON IN POSITION


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BREAKWATER CASE STUDIES


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PARADIP PORT


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PARADIP PORT


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PORT OF VISAKHAPATNAM LAYOUT OF OUTER HARBOUR


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CHENNAI PORT


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TUTICORIN PORT


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MORMUGAO PORT


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NEW MANGALORE PORT


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NEW MANGALORE PORT


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KAKINADA PORT BREAKWATER


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MOPLABAY CANNANORE


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FISHERIES HARBOUR


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REHABILITATION OF BREAKWATERS


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CONSTRAINTS IN REHABILITATION OFBREAKWATER


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BREAKWATER

CAUSES OF DAMAGE


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Freak waves of 4 m to 8 m height attackedbreakwater on 10 April 1987

Breakwater was in construction stage. Breakwater was designed for 4.0 m waves.

Higher waves overtopped the breakwater.


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DAMAGED BREAKWATER AT PORBANDAR


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Causes of damage

Severe cycloneof June 1998caused total damage to 600 mlength of breakwater from the

roundhead.

Higher waves than designwave lead to overtopping oflower crest


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construction of breakwaters

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