Underwater Tunneling

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Seminar onUnderwater tunneling

NAME: ARIJIT GHOSH

ROLL NO: 20105053

GUIDED BY : MR. SANTOSH KUMAR DAS

UNIVERSITY INSTITUTE OF TECHNOLOGY , BU


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INTRODUCTION:

Constructions of large infrastructures in the sea are supported by a lotof special construction techniques. For instance, the petroleum resourceindustry has developed many innovated techniques such as under waterdrilling, platform construction, pipe installation. Some of these techniquapplied to construction of sub-sea facilities in the field of civil engineerinnaturally. A typical structure, to which such techniques could be applied,underwater tunnel. Constructing a tunnel, however, is one of the most cochallenges in the field of civil engineering. Many tunnels are consideredtechnological masterpieces and government have honoured tunnel enginheroes.


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DEFINITIONOFTUNNEL:

A Tunnel is an Engineering Structure, artificialgallery, passage or roadway beneath the ground,under the bed of a stream or through a hill ormountain.An undersea tunnelis a tunnel which is partly or wh

constructed under a body of water. They are often uwhere building a bridge or operating a ferry link isimpossible, or to provide competition (or relief) forexisting bridges or ferry links. There are many reasofor building an undersea tunnel as opposed to theconstruction of a bridge or establishment of a ferry


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Advantages of tunnels:

1. For carrying public utilities

2. Tunnel may be cheaper than bridges and open cuts.

3. Tunnel save tearing up of expensive pavements, so lesser

maintenance costs by providing protection from natural influences.

4. Cost of hauling is decreased due to lighter grades, possible in tunne

5. Aerial warfare and bombing of cities have given intangible value to t

Compared to bridges:

One such advantage would be that a tunnel would still allow shipping to

bridge would need to be an opening or swing bridge to allow shipping t

can cause traffic congestion. Conversely, a higher bridge that does allow

be unsightly and opposed by the public. Bridges can also be closed due weather such as high winds. Another possible advantage is space: the d

ramp leading to a tunnel leaves a smaller footprint compared to the up

required by most bridges.

Tunneling will generate soil that has been excavated and this can be use

new land, as was done with the soil of the Channel Tunnel


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Advantages Compared to ferry link:

As with bridges, albeit with more chance, ferry linkswill also be closed during adverse weather. Strongwinds, or the tidal limits may also affect the workingsof a ferry crossing. Travelling through a tunnel issignificantly quicker than travelling using a ferry link,shown by the times for travelling through the ChannelTunnel (7590 minutes for Ferry and 21 minutes onthe Euro star.


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Disadvantages of Tunnels:

Construction requires long time in completing as compared tocuts.Specialized equipments make tunnels costlier than open cuts

Compared to bridges Tunnels require far higher costs of security and construction thbridges. This may mean that over short distances bridges may

preferred rather than tunnels (for example Dartford Crossing)stated earlier, bridges may not allow shipping to pass, so solutsuch as the Oresund Bridge have been constructed.

Compared to ferry links As with bridges, ferry links are far cheaper to construct than tu

but not to operate.


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CLASSIFICATION OFUNDERWATERTUNNEL:

UnderwaterTunnel

BoredSubmerged

floatingImme

tub


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Bored tunnel shall beconstructed when the groundor waterbed is appropriate forexcavating and preferred for

deep tunnels. There are twoalternative methods to build abored tunnel: Drilling-blastingmethod or by using a tunnel-boring machine. Although aTBM machine with a circularcross-section excavates the

soil without disturbing it andproduces a smooth tunnelwall, bored tunnel is onlysuitable for self retaining soils(TCRP Report/NCHRP Report2006).


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submerged floating tunnel

an archimed bridge is a very in the world. Only, Norwegiahave submerged floating tunthe design phase. Unlike theunderwater tunnels, submertunnel (SFT) is not buried to is suspended above the wateanchorage to the ground witrequires less substructure ancompared to the other two aNonetheless , SFT is only apfjords, deep seas, and Dee la


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An immersed tube tunnel is made up of many prefabricatetubes constructed on land, which are then floated and moveits dredged location by remoras in the sea. The tubes arelowered and connected with each other underwater. Then, twater is pumped out and the segments are covered with thebackfill materials. It is preferred if the water depth is not larthan 60 m. and the waterbed is suitable for dredging, such asoft sandy, silt or alluvial soils


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CONCEPTUAL DISEGN OF THE TUNNEL:

The greatest difficulty encountered during the construction of this tunnecontrolling the water inflow into the excavation. For this reason it was dea tunnel with the least possible width and to plan a constructive process tguarantee the stability in all the constructive phases.

For that it was decided that the tunnel should have two traffic levels, justthe Line 9, but with space for only one track in each one of them.This typology allows to consider the tunnel construction in two basically iphases;since the concrete slab that permits circulating on the upper level facilitatof the first constructed section.In addition, once the first phase excavation has been closed, a wall of mic

foreseen in order to facilitate the excavation of the lower part of the tunnconcept of the tunnel the problems focus on controlling the water inflow excavation front in the stretches in which the soil is heterogeneous and, cmore permeable.In order to control the probable water inflow into the front, when more pwere excavated, two actions were anticipated: firstly, lowering of the watsecondly, reducing the soil permeability through jet-grouting combined wgrouting


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CONCEPTOFTHEWATERPROOFINGSYSTEM

The waterproofing of a tunnel is a loose laid system. In case of a

leakage, the water is able to enter between the geo membrane

concrete shell and will look for the weakest point of the concretstructure. In general it is the joint between 2 concrete blocks. Incomplexity of the waterproofing, the possibility of leaks occurriafter installation of the waterproofing system must be considerTherefore it makes sense to plan the waterproofing system in suway that a repair is possible after finishing the construction, witperforating the concrete, and without damaging the waterproosystem.


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Thi b hi d h h j i Fi i l


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This can be achieved through two jointmethods:

The first one is to create compartmentswith water stops to limit the spreading ofthe infiltrating water over an importantlength of the tunnel.

The second one, is to place injectiondevices to have the possibility to repairleakages after having poured the concrete.

Components of the waterproofing system:

Geotextile minimum 500 g/mPolypropylene (no Polyester), dependingon the surface.

Geomembrane of homogenousthermoplastic material like PVC-P, TPO,min 2,0 mm, transparent (Frenchprescription) or with signal layer.

Fixing elements.

Reinforcement strips to protegeomembrane in the areawhefor concrete shell finishes.

Protection geomembrane (Fr

prescription)

Anchors if necessary to hold treinforcement of the inside

concrete shell.

Water stops

Injection device


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List of notable examples:Thames TunnelThe oldest underwater tunnel in the world.

(0.4km) (1825 - 1843).Severn TunnelOne of the oldest underwater tunnels in the w(3.62 km) (1873 - 1886).Chesapeake Bay Bridge Tunnel(23 mi), connecting VirginiaBeachwith the Eastern Shore of Virginia(1960 - 1964).New Elbe Tunnel, Hamburg, Germany, 8-lane road tunnel

crossing the Elbe river (1968 - 1975).Vard Tunnel(2.9 km), connecting the small island communiVard in northern Norway to the mainland (1979 - 1982).Seikan Tunnel, world's longest undersea railway tunnel (53.9km), when non-undersea portions of the tunnel are alsomeasured (1971 - 1988).
http://en.wikipedia.org/wiki/Thames_Tunnelhttp://en.wikipedia.org/wiki/Severn_Tunnelhttp://en.wikipedia.org/wiki/Chesapeake_Bay_Bridge_Tunnelhttp://en.wikipedia.org/wiki/Virginia_Beachhttp://en.wikipedia.org/wiki/Virginia_Beachhttp://en.wikipedia.org/wiki/Eastern_Shore_of_Virginiahttp://en.wikipedia.org/wiki/Elbe_Tunnel_(1975)http://en.wikipedia.org/wiki/Vard%C3%B8_Tunnelhttp://en.wikipedia.org/wiki/Seikan_Tunnelhttp://en.wikipedia.org/wiki/Seikan_Tunnelhttp://en.wikipedia.org/wiki/Vard%C3%B8_Tunnelhttp://en.wikipedia.org/wiki/Vard%C3%B8_Tunnelhttp://en.wikipedia.org/wiki/Vard%C3%B8_Tunnelhttp://en.wikipedia.org/wiki/Elbe_Tunnel_(1975)http://en.wikipedia.org/wiki/Eastern_Shore_of_Virginiahttp://en.wikipedia.org/wiki/Virginia_Beachhttp://en.wikipedia.org/wiki/Virginia_Beachhttp://en.wikipedia.org/wiki/Chesapeake_Bay_Bridge_Tunnelhttp://en.wikipedia.org/wiki/Severn_Tunnelhttp://en.wikipedia.org/wiki/Thames_Tunnel


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REFERENCES Google.comAkimoto, K., Y. Hashidate, H. Kitayama, and K. Kumagai. 2002. Immetunnels in

Japan: Recent technological trends. Underwater Technology, Proceedin2002 International Symposium on 81-86Anastasopoulos, I., N. Gerolymos, V. Drosos, T. Georgarakos, R. KourkG.Gazetas. 2007. Behaviour of deep immersed tunnel under combined nrupture deformation and subsequent seismic shaking. Bulletin of EartEngineering 6(2): 213.

Akan, AslE., . zen. 2007. Bursa YeilTrbeninsonlu elemanlar yndepremanalizi.Deprem Sempozyumu Kocaeli 2007. http://kocaeli2007.kocaeli.e(accessed September 5, 2008).Baltzer, W., P. Hehengeber. 2003. The case for immersed tubes. TunneTunneling


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Conclusion :

Complex immersed tunnel projects can be made feasible and exe

within planned cost, time and risk.It requires however realistic planning, proper establishment ofexpectations, experienced specialists involved, good projectmanagement and effective collaboration between specialists frodesigners, contractors and owners.Submerged floating tubes allow construction of a tunnel in extredeep water, where conventional bridges or tunnels are technical

difficult or prohibitively expensive. They would be able to dealwith seismic disturbances and weather events easily (as they havsome degree of freedom in regards to movement), and their struperformance is independent of length (that is, it can be very longwithout compromising its stability and resistance).On the other hand, they may be vulnerable in regards to anchorssubmarine traffic, which therefore has to be taken in considerati

when building one.


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Underwater Tunneling

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