A submerged floating tunnel is a tunnel that floats underwater, supported by buoyancy. It consists of prefabricated concrete or steel tube sections joined together. The tube is placed deep enough below the water surface to avoid traffic and weather. Submerged floating tunnels have advantages over bridges such as lighter construction load and less impact from earthquakes. They can be built faster without issues from wind or seas. Traffic can also run faster through them compared to ferries.

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2. SUBMITTED
BY
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REG.NO: 15012267
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3. ∗ A Submerged Tunnel is
a tunnel that floats in water,
supported by its buoyancy.
∗ The tube is placed underwater,
deep enough to avoid water
traffic and weather.
What is SFT ???What is SFT ???
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4. The big advantage of a submerged floating
tunnel compared to a bridge is the lightlylightly
loaded constructionloaded construction..
Flexible submerged tunnel has much lessless
problems with earthquakesproblems with earthquakes which can
happen in this area.
Floating tunnel can be built fast from both
shores having no problems with wind orno problems with wind or
high seashigh seas.
WHY THIS.??WHY THIS.??
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5. Moreover traffic can run very fast through
this tunnel compared to ferry link.
Due to lesser contact with the sea bed it has
lesser possibilities of chemical reaction with
the construction material & the sea bed soil
strata.
The downward ramp leading to a tunnel
leaves a smaller footprint compared to the
upward ramps required by most bridges.
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6. STRUCTURAL COMPONENTSSTRUCTURAL COMPONENTS
OF SFTOF SFT
These components should provide strength and
stiffness against the various forces acting under
the watersurface.
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7. External shape can be circular , elliptical or
polygonal.
It may be constructed of steel or concrete.
Corrosion protection is the main issue.
 Tube is composed of elements of length
varying from one hundred meters to half a
kilometre.
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10. It is an “underwaterbridge” with
foundations on the
bottom, in principle the columns are in
compression but
they may also be a tension type alternative.
Waterdepth will play an important role in
this case and a
few hundred meters depth is considered a
limit at the
present time.
However, much deeperfoundations
are at present underinvestigation.
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11. It is based on tethers being in tension in all future
situations.
No slack in these tethers may be accepted in any
future load cases.
The tethers are vertical or a combination of
vertical and inclined.
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12. It is interesting as it has no anchoring at all except
at landfalls and is then independent of depth.
There is obviously a limit to the length but only
further development will answer this.
Perhaps an alternative for light traffic should be
designed, possibly a 100 or 200 meter long.
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13. ∗ The connections of the tube to the shore
require appropriate interface elements to
couple the flexible water tube with the much
more rigid tunnel bored in the ground.
∗ This joint should be able to restrain tube
movements, without any unsustainable
increase in stresses.
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14. 1) Precasting
2) Joining of tunnel segments by using rubber gasket.
3) Foundations
4) Anchoring of cables.
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15. ∗ Huge tunnel sections are constructed on dry dock.
∗ The procedure consists same as that of precast
construction.
∗ Dry dock is flooded and the panels are transported to
their respective places.
∗ Sinking of the panel is controlled by the use of ballast
tank as in case of submarines.
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16. ∗ After the submersion of different panels in water they are
connected with one another by using a rubber gasket.
∗ Another procedure includes trapping of water between
the joints and then removing it afterwards.
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17. ∗ The application consists same as that of in caisson
foundation.
∗ A hollow chamber is penetrated down the sea bed as
shown which evacuates the water trapped inside it by a
valve present on its top surface.
∗ Such type of foundations are been used for the offshore
oil rig plants.
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18. ∗ After the foundation work is completed the cables are
anchored to the floating tunnel which will avoid its
movement and will place it firmly in alignment.
∗ This operation can be carried out by divers.
∗ Finally the tunnel will be in position and ready to use.
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19. ∗Invisible
∗Length only from shore to shore
∗Very low gradient
∗Access to underground service-parking
space at ends
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20. Crossing waterways, whether being from main land
to islands in the sea, perhaps the one we are at now
will in many cases meet protests both from tourist
interests and also from the public in general.
Lakes of special beauty or perhaps historical value
should be preserved for the future, the crossing of
such areas and lakes with SFT may make this
possible.
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21. ∗ The actual SFT structure is only as long as the
distance between the shores.
∗ If desired the SFT may be connected directly
to tunnels and then be completely out of sight
for any desired distance.
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22. Crossings with undersea tunnels or
bridges
will frequently mean longer structures
with consequently higher costs
An SFT crossing may have a very gentle
gradient or being nearly horizontal giving
considerable savings in energy used by
traffic.
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23. As the SFT may continue in tunnels having crossed
the waterway.
It is possible to arrange parking places or service
areas under ground
Provide access to the surface by lifts directly into
cities or recreational areas.
These possibilities may be one of big advantages in
future, in fact for all types of tunnels.
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24. Advantages of SFTAdvantages of SFT
Allow construction of tunnel in extremely
deep water.
Any type of cross sectional area can be
provided since being prefabricated.
No obstruction to navigational routes as
compared to conventional bridges since all
of the tunnel being placed underwater.
Construction activities has less harmful
effects on aquatic life.
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25. Disadvantages of SFT
Cost: Due to lots of material and machinery involved in
project, estimated cost is nearly 1.2 Thousand core
dollars.
Fire: It is difficult to rescue people if fire will break out
in train and also to face the problems due to the smoke
of fire.
Collision: If in case of collision of two trains took
place, it is very difficult to rescue the people.
No Stoppage: It is very difficult to stop the train
travelling on such a high speed.
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26. The submerged floating tunnel will set up new trends in
transportation engineering.
With this advances in technology that will reduce the
time required for travelling.
Make the transportation more effective by hiding the
traffic under water by which the beauty of landscape is
maintained.
 Benefits can be obtained with respect to less energy
consumption, air pollution and reduced noise emission.
For wide and deep crossings the submerged floating
tunnel may be the only feasible fix link.
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•Christian Ingerslev “Immersed and floating tunnels” Science Direct
VOL. 4 ,2010 PP:51-59.
•Keqian Zhanga, Yiqiang Xianga,*, Yinguang Dub “Research on
tubular segment design of submerged floating tunnel” Science
Direct VOL. 4,2010 .PP:195-205.
•Yiqiang Xiang*, Chengxi Liu, Keqian Zhang, Qiangqiang “Risk
analysis and management of submerged floating tunnel and its
applications” Science Direct VOL. 4,2010,PP:107-116.
•Bernt Jakobsen “Design of the Submerged Floating Tunnel
operating under various conditions” Science Direct VOL. 4 2010
,PP:71-79.
•Fei Ge*, Wei Lu, Xiaodong Wu, Youshi Hong “Fluid-structure
interaction of submerged floating tunnelin wave field” Science
Direct Vol 4 2010 PP:263-271.

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