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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)

November 5, 2009 4

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

November 5, 2009 5

To protect or Not to protect

November 5, 2009 6

Building codes in eroding areas

see also lecture ct5307

Coastal Zone Management

November 5, 2009 7

Examples of protection

November 5, 2009 8

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

November 5, 2009 11

Jump and Bore

November 5, 2009 12

Flowing water vs. moving object

November 5, 2009 13

Mixing layers and Jet

November 5, 2009 14

Pipe flow and Porous flow

wall flow grenslaag

mixing layer menglaag

oscillating flow

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Cause and Effect

November 5, 2009 16

Ill-designed protections

November 5, 2009 17

Contradicting demands

November 5, 2009 18

Failure Mechanisms

November 5, 2009 19

Fault tree

November 5, 2009 20

Steel and Granular Material

November 5, 2009 21

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

November 5, 2009 22

Mobility vs. Stability

November 5, 2009 23

Strength increase or Load reduction

November 5, 2009 24

reminders (1)

energy head

= location head

+ pressure head

+ velocity head

hydrostatic pressure

(Torricelli)

transfer of velocity into

pressure

November 5, 2009 25

reminders (2)

(Chezy)

(Darcy)

(effective stress = total

stress - water pressure

deep water wave length

shallow water wave length

November 5, 2009 26

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