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November 5, 2009
1
Introduction
Chapter 1
ct4310 Bed, Bank and Shoreline protection H.J. Verhagen
Faculty of Civil Engineering and Geosciences Section Hydraulic Engineering
November 5, 2009 2
Material used:
Book:
Book is available from
VSSD
ISBN 90-407-1683-8
400 pages,
£ 35
November 5, 2009 3
Material used (2)
• Study guide
• reminders
• examination
• acsido
• Cress - www.cress.nl
• Quizz
(http://www.kennisbank-waterbouw.nl/oefening/index.htm)
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Introduction
• protection of the boundary between land and water
• objective:
• learn to design a structure for the protection against undesired erosion;
• design structures based on understanding of processes
• knowledge needed:
• fluid mechanics
• soil mechanics
• hydraulic engineering
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To protect or Not to protect
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Building codes in eroding areas
see also lecture ct5307
Coastal Zone Management
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Examples of protection
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Value for money
November 5, 2009 9
Focus during design process
November 5, 2009 10
science or craftmanship ?
d
d
FF Fv k
x
F T
T T
T
v kd
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Jump and Bore
November 5, 2009 12
Flowing water vs. moving object
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Mixing layers and Jet
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Pipe flow and Porous flow
wall flow grenslaag
mixing layer menglaag
oscillating flow
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Cause and Effect
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Ill-designed protections
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Contradicting demands
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Failure Mechanisms
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Fault tree
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Steel and Granular Material
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load and strength
• transport, damage = f( mobility parameter, geometry, etc.)
• stability (parameter) = f (accepted damage, geometry, etc.)
The stability parameter is a critical value of the
mobility parameter
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Mobility vs. Stability
November 5, 2009 23
Strength increase or Load reduction
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reminders (1)
energy head
= location head
+ pressure head
+ velocity head
hydrostatic pressure
(Torricelli)
transfer of velocity into
pressure
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reminders (2)
(Chezy)
(Darcy)
(effective stress = total
stress - water pressure
deep water wave length
shallow water wave length
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reminders (3)
ReuL
uFr
gh
Reynolds number, inertia vs. viscosity
for open channel flow, with L=h,
Re > 2000 to 3000
Froude number,
kinetic energy vs. potential energy
Fr < 1 sub-critical flow
Fr = 1 critical flow
(u = celerity of shallow water waves)
Fr > 1 super-critical flow