A Sustainable Approach for

Marine Reclamations in Coastal Cities

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YIN Jian-Hua (殷建華)

The Department of Civil & Environmental Engineering

The Hong Kong Polytechnic University, Hong Kong, China

(香港理工大學 土木及環境工程系)

3rd Annual Forum of UGI Consortium for Sustainable Urban Development:

Enhancing Urban Sustainability - The Way Forward

(22 June 2019, 3F of Jockey Club Innovation Tower, PolyU, Hong Kong)

1. Background and Motivation

1.1 Burning Social Issues in Hong Kong

• Hong Kong is the most expensive city among all cities (≥5 million people) in the

world.

• The waiting time for public housing in Hong Kong has been increased to 5.5

years in 2018

1.2 Short-supply of Land and Marine Reclamations

• There is a severe problem of short-supply of land in Hong Kong for further

development to meet long-term community needs.

• Marine reclamations provide the most feasible solution for a stable supply of land

in Hong Kong for mid-term and long-term developments.

• Marine reclamations are also important to developments in the Guangdong-Hong

Kong-Macau Greater Bay Area (GBA) and other coastal cities.

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1.3 The main objective of our new Research Impact Fund (RIF) project

To develop a sustainable approach for super-fast economical and

environmentally-friendly marine reclamations in GBA/costal cities.

“Lantau Tomorrow” reclamation in Hong Kong proposed in

“The Chief Executive’s 2018 Policy Address”:

“Lantau Tomorrow”: 1700 hectares of land for 700,000 to

1,100,000 people

“Lantau Tomorrow”

Macau Reclamation

Plan (350 hectares):

Shen Zhen Qianhai Reclamation Plan (2800 hectares):

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A-A section: Vertical drains with vacuum pre-loading and sea water for additional loading

A-A section: Dredging and blow-filling stage

Sketch of proposed reclamation area in Tung Chung, Hong Kong.

Water flow

New sustainable approach:

• Using Fibre Reinforced

Polymer (FRP) pipe piles to

build impermeable seawalls

• Using local free marine deposits

• Speeding up consolidation of

soils using Vertical Drains

(VDs) with vacuum preloading

2. A New Sustainable Approach for Super-fast Economical

and Environmentally-friendly Marine Reclamations

Sketch of proposed

“Lantau Tomorrow”

reclamation project (1700

hectares)

FRP pipe piles

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Example: 1700 hectares (17 km2) (average water depth of 15m, reclaimed to +6

mPD (2m settlement compensation)

Sand volume =17× 106 (m2)× (15+6+2)(m)=3.91× 108 (m3)

Super-fast: Ship imported sand, use 20 barges with load capacity of

4000 tons:

Time required (24 hrs/day) is: 133.9 years

Utilize local marine deposits, use 20 dredge ships at a blow-

filling speed of 4000 m3/hour (assume only 40% of the mud is solid):

Time required (24 hrs/day) is: 1.39 year

Economical: Local marine deposits are free

Cost of imported sand: 3.91× 108 (m3)× 150 ($/m3)

=$5.865× 1010=HK$58.65 billion dollars

Environmentally-friendly: ? (discuss more later)

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“Tian-Kun” dredging and blow-filling ship (17000 tons of displacement): dredging

depth up to 35m; blow-filling speed at 6000 m3/hour at a distance of 15 km away.

“天鯤號”(排水量17000噸): 船長140米，寬27.8米，最大挖掘深度可達35米，能以每小時6000立方米的速度將海泥/沙以及海水混合物輸送到最遠15公里地方。

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3.1 Key Questions by Local Community

(a) How will dredging and filling activities affect marine eco-system?

Any protection measure?

(a) Can soft Hong Kong Marine Deposits (HKMD) be used to construct reclamations?

Settlement prediction and control?

3.2 Scientific Issues and New Contributions

(a) How to access marine eco-system affected by marine reclamation?

A novel eDNA approach.

(b) Dispersion-diffusion-sedimentation of soil particles and influence?

A more advanced 3D numerical model.

(c) Mechanisms of “mud” becoming “solid” ground and creep settlement?

A new large-scale physical model study and laboratory test study.

(d) How to predict and control settlements of dredged and blow-filled mud?

A new numerical method and a new simplified method.

3. Key Questions and Scientific Issues

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4. Comprehensive Research Program and Methodology

Task 1:

Feasibility Study

and Identifying

the Best Scheme (JH Yin + Co-PIs)

Task 2:

A New Water-

tightness FRP

Pile Seawall (JG Dai + Co-PIs)

Task 3:

Super-fast Blow Filling

of Local HKMD, Self-

weight Consolidation,

and Fast Consolidation

Using VDs and Vacuum

Preloading (ZY Yin + Co-PIs)

Task 4:

Dispersion-diffusion-

sedimentation of Soil

Particles, Marine

Ecosystem Impact

Assessment, and

Protection Measures (WH Wai + XD Li)

Task 5:

Prototype Field

Trial of the

Proposed New

Approach (3 partners +

PC + Co-PIs)

Task 6:

Evaluation of

Performance, Advantages,

and Application Ranges

of the New Approach and

Guidelines (all)

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• Use of FRP (Fibre Reinforced Polymer) pipe

piles to build a water-tight seawall to surround a

reclaimed area.

• FRP is immune to corrosion, light-weight, and

has a very high strength (3 times of normal steel).

• FRP cables and deep cement mixing method may

be used to increase the stability of the FRP wall.

4. Comprehensive Research Program and Methodology

Task 2: Study of a water-tightness FRP pipe pile seawall to surround a

reclamation area

DCMDCMDCM DCM

Rock fill and

rock/concrete armour

FRP pipe pile wall (water-tight)

FRP cables will be used to tie the pipe piles

10

0

500

1000

1500

2000

2500

3000

3500

4000

0 10000 20000 30000

Tensil

e str

ess

(MP

a)

Tensile strain ()

High-modulus

carbon FRP

Steel

High-strength

carbon FRP

Glass FRP

Aramid FRP Basalt FRP

Steel

Sheet pile cells (31m in diameter)

Hong Kong-Zhuhai-Macao Bridge

Hong Kong Boundary Crossing Facilities –

Reclamation Works

Hong Kong-Zhuhai-Macau Link Projects

– two artificial islands

钢圆管 (steel pipes)直径22米，最高50.5米，一共120个 11

Task 3: Study of local marine deposits, fast consolidation, and settlement control

Task 3(a): Large-scale physical modelling and laboratory test study

4. Comprehensive Research Program and Methodology

• Study of mechanisms

• Data for verification of new models and methods

Cables of steel or

FRP to tie up the

pipe pile wall

Vacuum

Pumps

DCM

columns

Vertical

drains

FRP concrete pipe

pile wall (water tight)

Blow-filled

HKMD

Reinforced

concrete tank

Geomembrane

A

A

Water

3 m

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Yin and Graham’s Elastic Visco-Plastic (non-linear) model (1989, 1994, 1996) was

considered as a milestone contribution in modelling creep of soils.

Matsuda et al. (2008)

Over 60 years

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A top journal (UK) in Geotechnics in the world

Task 3(b): Numerical modelling study

and simplified method for

settlement prediction and

control

4. Comprehensive Research Program and Methodology

See:

Nash, DFT and Ryde SJ (2001) , Nash. DFT

and Matthew Brown (2015) (UK)

Le, TM, Fatahi, B, Disfani, M, Khabbaz, H

(2015) (Australia)

4. Comprehensive Research Program and Methodology

The initial water content of 125.5% (liquid state) of the bentonite slurry was reduced to 64.5% (more like a soil) (supported by China Harbour Engineering Company Limited).

Visit by Professor Dr

Norbert R. Morgenstern

from University of

Alberta, Canada

Fast consolidation of bentonite slurry using VDs and vacuum preloading:

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0

500

1000

1500

2000

0 5 10 15 20

Cement/Soil Ratio Aw%

w i=100%

w i=80%

w i=60%

qpeak (kPa)

Peak deviator stress qpeak (kPa) vs. Aw and wi from

UC tests (after Yin and Lai 1998)

Deep Cement Mixing (DCM) of soft soils:

Task 4: Study of marine eco-system, dispersion-diffusion-sedimentation of soil

particles, and marine environmental protection

4. Comprehensive Research Program and Methodology

After Dredging /

filling

Before

eDNA=environmental DNA

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9 7 ' Co a s t l i n eNo o b s ta c l e

2 m /s1

0 25,000 50,000

meters

Effective methods for marine environmental protection:

• Confinement of dredging and filling areas by multiple curtains.

• See a table below for advantages of our new approach for

marine environment protection:

4. Comprehensive Research Program

and Methodology

Existing Methods New Approach Advantages of New Approach

Using dredged

sand

Using dredged

local marine soils

The same dredging issues

Conventional

(permeable )

seawalls

Impermeable

seawalls, vertical

drains with

vacuum

preloading

• Contaminated soils are confined;

• Dirty water can be pumped out and treated;

• Construction waste (inert√ and non-inert?) can be used;

• Mining wastes may be used;

• Wastes from furnaces may be used;

• Soils in harbor/port/rivers can be used (one stone two

birds);

• Marine soils in less or insensitive seabed can be dredged

and pumped to fill (15 km away);

• General fill can be used for sure.

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Walls (right) >

Fill (below)

Concrete

Blockwork

Seawall

Steel

Tubular

Pile Wall

FRP

Tubular

Pile Wall

Deep

Cement

Mixing

Steel or

FRP

Cable

Ties

Stone

Columns

/ Sand

Piles

Other

Seawall

Types

Sandfill Option 1

Blow-filling HKMD

Option 3 Option 2 Option 2

Option 3

Option 2

Option 3

General Soil Fill Option 3 Option 2

Construction Wastes

Option 2

Contaminated Soil/Other Wastes

Option 2

Vertical Drains Option 1 Option 3 Option 2

Fill Surcharge Option 1 Option 3

Vacuum Loading Option 2

Additional Water Surcharge

Option 2

Selection of different techniques for marine reclamations by considering

• marine geological conditions,

• environmental concerns,

• available materials,

• time, and cost.

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Can Hong Kong Marine Deposits be used to construct

reclamations? Settlement prediction and control?

Successful cases in many coastal cities on treatment of

dredged marine soils/mud:

PolyU: Bentonite slurry: • Vertical Drains (VDs) +

vacuum preloading; • Water content of 125.5%

(liquid state) was reduce to 64.5% (soil like).

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Tianjin soft marine soils: • Reclamations using dredged marine soils; • VDs + vacuum preloading; • There are many successful cases in Tianjin.

The tallest building (500m) on

reclaimed land in Tianjin

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Dalian soft marine soils:

• VDs + vacuum preloading of dredged

mud;

• Reference: 《大连大窑湾三期软基处

理》中交水运规划设计院有限公司,

2011年2月20日.

Property Bentonite Slurry Tianjin Clay Dalian Clay HK Marine Deposits

Permeability

k

10-14 m/sec ~

10-13 m/sec

10-10 m/sec ~

10-9 m/sec

10-10 m/sec ~

10-9 m/sec

10-9 m/sec ~ 10-8 m/sec

Cae 4% ~ 8% 1.5% ~ 4% 1% ~ 3% 0.3% ~ 1%

Clay content 80% 60% 50% <15%

Clay minerals Bentonite/

montmorillonite

Mix of illite and

montmorillonite

Mix of illite and

montmorillonite

Kaolinite and illite

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HK marine deposits:

Cae=0.3% to 1%

“primary consolidation”

“主固结”

“secondary consolidation

“次固结”

Cae

Dalian clay:

Cae=1% to 3%

Tianjin clay:

Cae=1.5% to 4%

Cae

Hong Kong Marine Deposits are “good” soft soils

5. Research Team, Collaboration, Budget, and Management

Partners:

(1) Works Branch of Development Bureau of HKSARG: the developer (government) for marine

reclamation projects in Hong Kong (site for field trial and other support).

(2) China Harbour Engineering Company Limited: a major contractor in HK (Support-in-kind).

(3) Fong On Geotechnics Limited: a major geotechnical company in Hong Kong (Support-in-kind).

Collaboration:

Professor CHEN Xiang-Sheng (Academician) from Shen Zhen University in GBA (Support-in-kind).

Budget and Period:

Budget: HK$14.1088 million including 30% (HK$4.23264 million) matching fund by PolyU+HKU.

Period: 60 months (from 30 June 2019 to 29 June 2024).

Management Plan:

• PC: Coordinating and managing the whole project

• 6 Co-PIs: Working on individual tasks and other relevant tasks as a team

• Three partners: providing advices, technical inputs, and support-in-kind in all relevant tasks

• Quarterly meetings and annual workshops. 21

PC: Jian-Hua Yin Wing Hong Wai

Sediment dynamics

Xiang-Dong Li

Environment assessment

Jian-Guo Dai

FRP structures

Zhen-Yu Yin

Marine reclamations

Andy Yat Fai Leung

Soil Mechanics

Quentin Zhong-Qi Yue

Geotechnical Engineering

(a) Advanced technology developed/applied: √

(b) Significance of the R&D study: √

(c) Roles of the government department:

• Since HKSARG is the sole client and authority for reclamations in

Hong Kong, the role of CEDD and other departments are critically

important for success of this RIF project;

• Departments of HKSARG have a good will to construct

reclamations for housing and infrastructural projects in order to

improve the quality of life in Hong Kong;

• But, these departments need co-operations among themselves; and

• CEDD and relevant departments/offices need strong technical

support from universities and industry in Hong Kong.

6. Key Problems to Be Addressed

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(d) Roles of R&D centres

• All R&D centres in Hong Kong related to marine reclamations

are welcome to work together.

(e) Roles of other collaborators

• Works Branch of Development Bureau of HKSARG: the developer (government) for

marine reclamation projects in Hong Kong (site for field trial and other support);

• China Harbour Engineering Company Limited: a major contractor in HK (support-in-

kind);

• Fong On Geotechnics Limited: a major geotechnical company in Hong Kong (support-

in-kind); and

• Professor CHEN Xiang-Sheng (Academician) from Shen Zhen University in GBA

(support-in-kind).

(f) Synergy in the collaborative project

• Collaboration among stake-holders and relevant parties are the success of the RIF

project;

• Collaboration will make advancements of science and technology.

6. Key Problems to Be Addressed (continued)

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A contribution to the quality of life and a harmonic society

for people in the Greater Bay Area/Coastal Cities!

A Feasible Solution to the Urgent Problem of

Short-supply of Land in Hong Kong

Thank you very much

for your kind attention

and questions

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