HULHULE-MALE’ BRIDGE PROJECT

EIA for the proposed Hulhule-Male’ Bridge Project
Table 7.4: Comparison Table of Main Bridge Foundation Construction
Designing
Scheme
Bearing
Capability
Construction
Scheme
Pile-group Foundation
• Bearing capacity meets the
requirements.
• Overall steel casing contributes to
joint load carrying and has strong
displacement control.
Overall steel casing
Caisson Foundation
• Bearing capacity meets the requirements.
• Poor displacement control
Prefabrication installation
Practicability
Construction
• Scheme is feasible.
• Technology is mature; there are
many successful projects cases in
China.
• Less process conversion,
implementing common
construction methods of bored
piles after the steel casing group is
in place.
• Need to choose the proper time
window, when hoisting the overall
steel casing.
• Scheme is feasible.
• Technology is mature, less application in China.
• The proper time window will need to be
selected for floating transportation and
installation of caisson.
• The height of 1000 t floating crane is 80~100 m,
exceeding aviation height limit demand of 45 m.
• More process conversion: prefabrication on the
basic semi-submersible barge, body pier, and
height pier, floating transportation of caissons,
sinking, basement excavation and levelling are
conducted in the floating state.
Period
9 Months 8.5 Months
Quality
Safety
Environment
Protection
• Difficulty of controlling the plane
position of steel casing is larger.
• It is easier to assure the quality of
pile foundation construction.
• The overall steel casing has a large
volume and heavy weight load.
• The transportation and installation
activities during construction carry
a certain level of safety risk.
• The small area of the steel casing
group has little influence on
seabed and marine animals and
plants.
• Bored pile construction needs to
be strictly controlled to avoid
sedimentation (especially mud
pollution).
• The prefabrication is conducted in semisubmersible
barges under a floating state, and
thus its quality is greatly influenced by the
environment.
• The quality of the pier body’s joint height when
floating on the water is greatly influenced by
environment.
• Handling of seabed basement has high quality
demand, Difficulty of controlling the planned
position and gradient of caissons installation is
higher.
• The pier body’s joint height when floating on
the water carries a higher level of safety risk.
• Transportation and installation of caisson via
floating have greater safety risk.
• The pit excavation area of caisson is larger,
which has great impact on seabed and marine
animals and plants.
Prepared by: CDE Consulting & China Shipping Environment Technology
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