A Sustainable Approach for Marine Reclamations in Coastal Cities 1 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) 3 rd 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)
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A Sustainable Approach for
Marine Reclamations in Coastal Cities
1
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.
2
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):
3
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
4
Example: 1700 hectares (17 km2) (average water depth of 15m, reclaimed to +6
(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
8
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)
9
• 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
12
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
13
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:
14
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
15
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.
16
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