breakwaters day 1 - introduction

BREAKWATERSBREAKWATERS

J.W. van der Meer, PhD. CEJ.W. van der Meer, PhD. CE

J.C. van der Lem MSc. CEJ.C. van der Lem MSc. CE

ROYAL HASKONING

J.C. (Cock) van der Lem M.Sc.Sr. Port Engineer

Maritime Advisory Group Rotterdam

Haskoning Nederland B.V.a company of Royal Haskoning

George Hintzenweg 85P.O.Box 8520

3009 AM Rotterdam The Netherlands

tel. +31-(0)10-4433666

direct +31-(0)10-4433722 mobile +31-(0)6-15006372

fax. +31-(0)10-4433688 e-mail: C.vanderLem@RoyalHaskoning.com

www.royalhaskoning.com

Contact detailsContact details

33BreakwatersBreakwatersFebruary 2011February 2011

SUBJECTS

• Rubble mound breakwaters (J.W. van der Meer)

• Vertical wall breakwaters (J.C. van der Lem)

• Berm breakwaters (J.W. van der Meer)

• Submerged breakwaters (J.W. van der Meer)

Vertical Wall BreakwatersVertical Wall Breakwaters

Objectives (end of the course)

• To be able to make an assessment of hydraulic loads against caisson breakwater

• To be able to make a preliminary design of a caisson breakwater (length, width, height)

• To be able to compare caisson breakwater against rubble mound breakwater

CONTENTS

• Day 1 – Introduction, set the problem

• Day 2 – PROVERBS parameter map (exercise) & design methods (functional requirements)

• Day 3 – Design methods (static analysis)

• Day 4 – Design methods (dynamic analysis)

• Day 5 – Worked example

DAY 1 - INTRODUCTION

• Information (readers)

• Functions

• Types

• Problem definition

• Design methods (intro)

ReadersIn lecture notes/distributed:

• Y. Goda, Ch. 4 Design of Vertical Breakwaters

(from: Random Seas and Design of Maritime Structures. 1985)

• S. Takahashi, Design of Vertical Breakwaters

(Short Coarse, ICCE, 1996)• PIANC; Breakwaters with Vertical and Inclined Concrete

Walls, Report WG 28, 2003• G. Cuomo: Wave impacts on vertical sea walls & caisson

breakwaters. PIANC On Course Magazine 127 van Mei 2007.

Readers (continued)Separate:

• PowerPoint presentations (el. platform)• PIANC WG 28 sub-group reports (el.

platform)• Overtopping manual:

www.overtopping-manual.com

Additional reading:Additional reading:• Oumeraci, H. et. al.; Probabilistic Design

Tools for Vertical Breakwaters (PROVERBS), February 2001 (ISBN 09 5809 248 8 / 249 6)

• Coastal Engineering Manual• The Rock Manual• Breakwat (Deltares formerly WL|Delft Hydraulics)

Gijon (Spain)IJmuiden (Netherlands)Kamaishi (Japan)Marsaxlokk (Malta)Ras Laffan (Qatar)

Vertical Wall Breakwaters - Vertical Wall Breakwaters - FunctionsFunctions

FUNCTIONS

• Wave protection in port/channel

• Protection from siltation, currents

• Tsunami protection• Berthing facilities• Access/transport facility

(breakwaters with vertical and inclined concrete walls)

• Conventional

Vertical Wall Breakwaters - Vertical Wall Breakwaters - TypesTypes

The caisson is placed on a relatively thin stone bedding.

Advantage of this type is the minimum use of natural rock (in case scarse)

Wave walls are generally placed on shore connected caissons (reduce overtopping)Mutsu-Ogawara (Japan)

TYPES (continued)

• Vertical composite

The caisson is placed on a high rubble foundation.

This type is economic in deep waters, but requires substantial volumes of (small size) rock fill

Algeciras (Spain)

TYPES (continued)

• Horizontal composite

The front slope of the caisson is covered by armour unitsThis type is used in shallow water. The mound reduces wave reflection, wave impact and wave overtoppingRepair of displaced vertical breakwaters (day 2) Used when a (deep) quay is required at the inside of rubble mound breakwater

Gela (Sicily, Italy)

TYPES (continued)

• Block type

This type of breakwater needs to be placed on rock sea beds or on very strong soils due to very high foundation loads and sensitivity to differential settlements

Alderney (Guernsey, UK)

TYPES (continued)

• Piled breakwater with concrete wall

Piled breakwaters consist of an inclined or curtain wall mounted on pile work.

The type is applicable in less severe wave climates on site with weak and soft subsoils with very thick layers.

Manfredonia New Port (Italy)

TYPES (continued)

• Sloping top

The upper part of the front slope above still water level is given a slope to reduce wave forces and improve the direction of the wave forces on the sloping front.

Overtopping is larger than for a vertical wall with equal level.Napels (Italy)

TYPES (continued)

• Perforated front wall

The front wall is perforated by holes or slots with a wave chamber behind.

Due to the dissipation of energy both the wave forces on the caisson and the wave reflection are reduced

Dieppe (France)

TYPES (continued)

• Semi-circular caisson

Well suited for shallow water situations with intensive wave breaking

Due to the dissipation of energy both the wave forces on the caisson and the wave reflection are reducedMiyazaki Port (Japan)

TYPES (continued)

• Dual cylindrical caisson

Outer permeable and inner impermeable cylinder.

Low reflection and low permeable

Centre chamber and lower ring chamber filles with sand

Nagashima Port (Japan)

• TYPES (continued)

• “Combi-caisson”

Sloping top

Semi-circular/perforated

Perforated front wall

Perforated rear wall

Vertical Wall Breakwaters - Vertical Wall Breakwaters - Problem definitionProblem definition

What is needed?

• Proper understanding of functional requirements

• Proper understanding of loads and resistance

• Insight in failure modes

• Understanding of breaking/non-breaking waves

Functional requirements

• Access

• Quay facilities

• Overtopping

• Transmission

Requirements: acces (pedestrians, supply traffic)

Piraeus (Greece)

Requirements: acces (harbour workers, traffic, oil piping)

Marsaxlokk (Malta)

Requirements: acces (harbour workers, traffic, LNG piping)

Ras Laffan (Qatar)

Requirements: acces (harbour workers, traffic, conveyors)

Porto Torres (Sicily, Italy)

Requirements: quay facilities (access, warehouses, sheds)

Constantza Port (Romania)

Requirements: quay facilities (access, warehouses, sheds)

Durres Port (Albania)

Requirement: limit overtopping and transmission

Marina do Lugar de Baixo (Madeira, Portugal)

Vertical Wall Breakwaters - Vertical Wall Breakwaters - Loads and resistanceLoads and resistance

Loads and resistanceLoads:

• Hydraulic loads• Weight

Resistance:

• Friction (mostly)• Soil bearing capacity

F Hf W U( )

SF M F H

W t M u

Failure modes (overall)

Hydraulic failure Geotechnical failure

Sliding Overturning Slip

Planar slip

Circular slip

Earthquake loading:

LIQUEFACTION

F Hf W U( )

SF M F H

W t M u

SF max

Failure modes (local)

Instability of mound Erosion of seabed Partial

Instability

UErosion Scour

F Hf W U( )

Example overall failure: Mutsu Ogawara Port, East Breakwater (Japan)

Example local failure: Catania Breakwater (Sicily, Italy)

Vertical Wall Breakwaters - Vertical Wall Breakwaters - Design methods (intro)Design methods (intro)

Impression of hydraulic forces (field)

Hydraulic Forces (laboratory)

iCam optical sensor (Deltaflume Deltares)

• Aerated impact

• The wave breaks before reaching the wall

• Air pocket entrapped in the water not on the wall

• Pressure varies gradually in time in phase with wave elevation

iCam optical sensor (Deltaflume Deltares)

• Air pocket impact

• The wave breaks closer to the wall

• A large air pocket is entrapped against the wall

• Large peak force by crest hitting wall

• Followed by small force oscillations

• Duration of the pressure peak: O(0.01 s)

• Flip through impact

• Forward moving wave crest and rising wave trough converge at same impact point

• No air pocket entrapped against the wall

• Large peak force by crest hitting wall accelating into vertical jet

• Very short duration of impacts O(0.01 s)

• Slosh impact

• Rising wave trough arrives at convergence point way before forward moving crest

• No air pocket entrapped against the wall

• Small forces with long durations

Hydraulic Forces

• Differentiate between non-breaking and breaking waves

• Identification of types of horizontal loading by means of the PROVERBS parameter map (distribute)

PROVERBS Definition of geometric parameters

d h1Bb

1:mBeq

• PROVERBS parameter map (also PIANC WG 28)

Beq = Bb + 0.5∙m ∙ hb

Vertical Wall Breakwaters - Vertical Wall Breakwaters - Design methodsDesign methods

• PROVERBS parameter map

Beq = Bb + 0.5∙m ∙ hb

Example: Sakata Detached Breakwater (Japan)

hs0.65

hs0.541

Hs 5.85mhb 4.87mhs 9m

hb ELberm ELbottomHeight of berm:

Hs 0.65 hsDesign wave height

hs ELwater ELbottomDesign depth

ELberm 3.63 mBerm elevation

ELwater 0.5 mDesign water level

ELbottom 8.5 mBottom elevation

Beq = Bb + 0.5∙m ∙ hb

What in case of low mound?

hs0.65

hs0.208

Hs 5.85mhb 1.87mhs 9m

hb ELberm ELbottomHeight of berm:

Hs 0.65 hsDesign wave height

hs ELwater ELbottomDesign depth

ELberm 6.63 mBerm elevation

ELwater 0.5 mDesign water level

ELbottom 8.5 mBottom elevation

• PROVERBS parameter map

Beq = Bb + 0.5∙m ∙ hb

Hydraulic Forces: evaluation of wave breaking

Sainflou Goda PROVERBSGoda (extended)

To be continued…..To be continued…..

((distribute PIANC WG 28 cases and PROVERBS mapdistribute PIANC WG 28 cases and PROVERBS map))

Homework: read the PIANC WG 28 caseHomework: read the PIANC WG 28 case

Next course: bring PIANC case, Proverbs map & calculatorNext course: bring PIANC case, Proverbs map & calculator

breakwaters day 1 - introduction

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