Nautical Bottom How to keep mud under control

(1)

Nautical Bottom – How to

keep mud under control

Seminário Internacional em Portos e Hidrovias

Rio de Janeiro

11 sep 2014

Joris Vanlede

Flanders Hydraulics Research

(2)

Zeebrugge

(3)

(4)

Zeebrugge

Seminar Internacional em Portos e Hidrovias

11 sep 2014 7

(5)

Zeebrugge

CMA CGM Marco Polo (dec 2012)

396m – 16,020 TEU ~15m

(6)

Nautical Accessibility

11 sep 2014 Seminar Internacional em Portos e Hidrovias 11

• Operational Limits

• Cross component of flow

• <2kn (~1 m/s) for Container vessels >200m

• <1,5kn (0,75 m/s) for incoming LNG carriers

• Accessibility window

• Nautical Bottom

(7)

Nautical Accessibility

(8)

Nautical Accessibility

11 sep 2014 Seminar Internacional em Portos e

Hidrovias 13

(9)

Nautical Accessibility

• Operational Limits

• Cross component of flow

• Nautical Bottom

• Siltation (mud)

• Definition of Nautical Bottom (evolution)

• Dual criterium

• Surveying

(10)

Zeebrugge Siltation

• ~4,000 TDM/tide (Neap Tide)

• ~12,000 TDM/tide (Spring Tide)

• Maintenance dredging: 5.15 x 10

6 _TDM/year

(2005-2011)

(11)

Nautical Bottom

PIANC-IAPH 1997:

The level where physical characteristics of the

bottom reach a critical limit beyond which contact

with a ship’s keel causes either damage

or unacceptable effects on controllability and

manoeuvrability

• Translate into a Practical Criterium?

• Practical Measurement Strategy

(12)

Nautical Bottom (1986)

Physical characteristics of mud

In Situ (Zeebrugge)

Depth

Rigidity

Density

210 kHz

33 kHz

Rheological transition

(13)

Nautical Bottom (1986)

• Rheology over depth

• Rheological transition

• Corresponding Density

• Choice of Critical Density

• Zeebrugge

1.15 t/m³ (untill 2004)

• Rotterdam

1.20 t/m³

• Nantes St-Nazaire, Bordeaux

1.20 t/m³

• Cayenne

1.27 t/m³

(14)

Nautical Bottom (check 1997)

11 sep 2014 23

Rheological transition

1987

Rigidity

De

pth

1997

Rheological transition 1

Rheological transition 2

(15)

Nautical Bottom

PIANC-IAPH 1997:

The level where physical characteristics of the

bottom reach a critical limit beyond which contact

with a ship’s keel causes either damage

or unacceptable effects on controllability and

manoeuvrability

• Practical Criterium

• Practical Measurement Strategy

• Knowledge on effect of mud on

ship controllability

and manoeuvrability

(16)

Nautical Depth Criterium

Zeebrugge (from 2004)

• Ship of certain draft

• Under Keel Clearance above

1.20 t/m3

• Minimum 10% of draft

• maximum penetration below

210 kHz

• Maximum 7% of draft

(17)

Dual Nautical Depth Criterium

Water Level (2,5m – 4,5m ampl)

(18)

Surveying

11 sep 2014 28

(19)

Dredging Practice

Dredging depth

-13,5 m LAT

-15,5 m LAT

TDM/dredging trip

500 – 1000

1500 – 2000

(20)

Nautical Bottom

• Density Criterion as a proxy for rheological behaviour

• Update of the criterion checked against ship

controllability and manoeuvrability

• Nautical Bottom definition in Zeebrugge

• Has changed in time

• Tailor-made

, not generic

• Implies surveying techniques

• Implies dredging practice

• Acceptance

(21)

Current Research Activities

• Investing in system understanding

• Sediment Testing Tank

• Consolidation Columns

• Rheological Measurements (lab)

• Towing tests: submerged cilinder

• Physical test facility

• CFD modelling

(22)

Sediment Testing Tank

(23)

Sediment Testing Tank

• Comparison and validation of

density monitoring devices

Name Device

Working principle

Manufacturer

/Company

1 D2ART

Cs-137 source

Seabed B.V.

2 Densitune

Tuning fork

Stema

3 Graviprobe

Accelerometer

dotOcean

4 HRDP; (before: DRDP,

Admodus USP)

Acoustical

Greiser und partner.

(24)

Consolidation Columns

11 sep 2014 37

Tracer

CT-scan

Columns

(25)

Consolidation Columns

• Zeebrugge

• Deurganckdok

• Rotterdam

• Ijmuiden

• Emden

(26)

Laboratory

11 sep 2014 39

Density

Rheology

Gamma (Cs 137)

densitoscan

Anton Paar DMA 35

Pycnometer

Anton Paar MCR301

(27)

(28)

CFD

11 sep 2014 41

(29)

(30)

CFD

11 sep 2014 43

• Feasibility study (FHR-Antea Group - Kuleuven)

• Can CFD be used as a tool to investigate the

navigation of ships above and in contact with mud

layers?

• Towing simplified geometry as a testcase

• Open Foam (Open Source CFD Software)

• Delivered end 2014