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What is SFT ?OÜ ANKURTUNNEL
Tõnu Ader+372 56244712
FinEst Link Final Conference on 7th of February
SFT
is Submerged Floating
Tunnel
Why prefer the Submerged Floating
Tunnel ?
Proposed Tallinn-Helsinki tunnel routs (by SWECO and Ankurtunnel)
Paljassaare –Kirkkonummi (Porkkala) - 59 kmViimsi (Püünsi) - Helsinki Eteläsatama)- 67 kmViimsi (Püünsi) – Kirkkonummi (Porkkala)-52 km
Depth in the gulf of Finland (by SWECO study)
Layout of the Submerged Floating Tunnel
General view of the proposedsubmerged floating tunnel
Types of the tunnel
Why underwater tunnels are not well-known ?
o Even bridges are the most common structures used for crossing water bodies, tunnels in water are by no means new in civil engineering.
o This is because it seems very tempting to replace the cumbersome and difficult land digging, especially if the tunnel is need to be dug into rock; but water environment does not need digging.
o Since about 1900, more than 100 immersed tunnels have been constructed.
o In some cases immersed tunnels also used which run beneath the sea or river bed. But when the bed is too rocky, too deep or too undulating submerged floating tunnels are used .
o The main problem in using underwater tunnels is complicated construction, because it is difficult to connect tunnel parts under water surface and keep them watertight.
Some points from underwater tunnel HISTORYo The first underwater tunnel was built over four thousand years ago, but floating tunnels are much more recent.
o Certainly an engineer and builder of railways, S. Préault , proposed but did not build an SFT across the Bosphorus in 1860, an elegant underwater railway viaduct on piers, located some 20 m below the surface.
o Per Hall proposed a deeper SFT for the Bosphorus in 1976, but by 1977 his proposal had become a buried immersed tunnel for environmental reasons (fish habitat). An immersed tunnel is now in place beneath the Bosphorus awaiting the last of the TBMs to reach it.
o Going back now to 1882, Edward Reed proposed a submerged railway tunnel across the English Channel supported on caissons, but Parliament in England rejected it for fear of invasion. It was patented and since then, many other patents have been taken out for SFT, including some in the UK, USA, Norway, Sweden and Italy. Once the first immersed tunnel had been successfully built in 1893, the way was open also for constructing SFT – initially at least those that would be pier supported.
o Since 1923, the potential of an SFT has been recognized in Norway as a way to create a practical castal highway across fjords that would otherwise be too deep even for bored tunnels to make sense; some of the existing bored tunnel connections even with 10% grades are very, very long. This need for shorter shallower tunnels for a number of fjord crossings has led to detailed investigations and field tests that still continue today. Private investors have examined a number of other locations. The first of a series of Strait Crossing Symposia in Norway began in 1986 (the fifth was in 2009) in which SFT have played an increasingly greater part.
Some old patents for submerged floating tunnel
US patent from the year 1968
THE TECHNICAL CHALLENGES OF BUILDING AN SFT
1. The need to prevent resonance vibrations and movements being
induced into the hollow tube as well as into the anchoring tethers under
different hydraulic and dynamic load conditions.
2. The practicalities of fabricating and placing of the tube elements,
installing the anchor systems, and realizing the landfalls either end.
3. Maintenance and repair of the submerged infrastructure.
4. Addressing the highly improbably, but perhaps possible, event of a
submarine or a sinking ship colliding with the suspended tube.
5. Public perception and operational safety. How to gain the confidence of
the public and assure the safety of the infrastructure to clients and the
insurance industry?
KNOWN WAYS FOR SFT CONSTRUCTION
o
The concept of submerged floating tunnels is based on well-known technology applied to floating bridges and offshore structures, but the construction is mostly similar to that of immersed tunnels:
o One way is to build the tube in sections in a dry dock; then float these to the construction site and sink them into place, while sealed; and, when the sections are fixed to each other, the seals are broken.
o Second possibility is to build the sections unsealed, and after welding them together, pump the water out. The ballast used is calculated so that the structure has approximate hydrostatic equilibrium (that is, the tunnel is roughly the same overall density as water), whereas immersed tube tunnels are ballasted more to weight them down to the sea bed. This, of course, means that a submerged floating tunnel must be anchored to the ground or to the water surface to keep it in place (which of these depends on which side of the equilibrium point the tunnel is).
o And third possibility is to use for tunnel building special connected to the tunnel end mobile watertight dock.
o In any case much attention is required for tunnel anchoring and there can be used piers or a tethers (anchors).
Deepwater concrete immersed-tube tunnel modules building in North America
The 11 concrete tunnel elements were cast in two cycles, called litters. Litter 1 included the first six elements and litter 2 the final five elements. After each litter was completed, the dry dock was flooded to float the elements so they could be towed the 220 nautical miles to the project site. (The Elizabeth River Immersed Tunnels Project)
Towing of the immersed tunnel element to Porthmoth in April 2015
Visual comparison of the Drogen tunnel Cross Section to 4 stores house and 12 m anchored tunnel (red)
CONCLUSIONo
The submerged floating tunnel will set up new trends in transportation engineering and which shows with the advances in technology that will reduce the time required for travelling.
o And make the transportation more effective by hiding the traffic under water by which the beauty of landscape is maintained and valuable land is available for other purposes.
o Benefits can be obtained with respect to less energy consumption, air pollution and reduced noise emission.
o For wide and deep crossings the submerged floating tunnel may be the only feasible fix link, replacing present day ferries and providing local communities with new opportunities for improved communication and regional development,
o especially if it can be built not very costly.
Known projects of
Submerged Floating Tunnels
Planned submerged floating tunnel in Sognefjord
Submerged floating tunnel with block anchors
And now closer to the particular idea
How to build such tunnel ?
Metal parts of the section of the module
One of tens prefabricated parts of module
Prefabricated module parts (5 from 10 needed)
Connection of two sections of the module
Two sections put together
Three sections mounted together
Adding the fourth section
For sections put together
5 sections together
6 sections together
7 sections
8 sections
11 m inside diameter module from 10 parts
Inner walls of the module
Module with inner walls
Example of the O-ring for modules (7m inner Ø)
Pressurizable O-ring for 12m module
Connecting the modules and adding the O-ring
Connected modules
Explanation for setting modules on angle
View of the setting modules on angle for submerging
General view of the tunnel with anchoring wires and escape modules
View of the cross section of the module connection
Cross section of the tunnel with equipment and with escape module
Anchoring of the module
Sumberging Tunnel from floating platform
Escape (capsule) module
Tunnel module with the escape capsule
Calculated table for different diametersItem Calculated data
Inner diameter 12 m 11 m 10 m 9 m 7 m
Outer diameter 13 m 12 m 11 m 10 m 8 m
Wall thickness 0,5 m 0,5 m 0,5 m 0,5 m 0,5 m
Length 20 m 20 m 20 m 20 m 20 m
Displacement 2653 t 2260 t 1900 t 1570 t 1005 t
Volume of the concrete 393 m³ 360 m³ 330 m³ 298,3 m³ 235,5 m³
Weight of the concrete (2.6 t/m³) 1022 t 936 t 858 t 776 t 611 t
Weight of the additional equipment 400 t 400 t 300 t 200 t 100 t
Applied to ropes 1231 t 924 t 742 t 594 t 294 t
Prise for 1 km of concrete (500€/t)≈ 35,55 M€ 33,4 M€ 28,95 M€ 24,4 M€ 17,75 M€
Inner pane 8,5 m 7,8 m 7m 6,4 m 4,9 m
Base data for the tunnel building cost calculation The calculation is based on the reinforced concrete tunnel module price calculation. Generally used in building precast concrete price is about 500 €/t;Approximate price for 1 km of 30 M€ (i.e. 30 000 €/m) and for 60 km 1.8 billion € total cost of the tunnel body.
a. General feasibility study by Mach 2018, 50000 €b. Design and permissions - 220 M€c. Tunnel parts and montage 1.8 billion € d. Anchoring steel rope (60 mm 240 km) 30 M€ e. Anchors and rope mountings (2000 € x 6000 tk ) 12 M€f. Profile O-rings (3000 € X 3000 tk) 9 M€g. Module skin (cover) and adhesives ≈ 10 M€h. Floating platform 200 M€i. Module reinforced concrete parts plant 100 M€J. Escape modules (50 000 X 120) 6 M€k. Waterproof safety gates (200 000 X 120) 24 M€L. Railway utility equipment, rails, etc 500 M€
In total: 2 911 000 000 € (≈ 3 billion €)
One low draft ship for floating platform
Floating platform with between deck and slip
A console for anchor drilling and mounting on the platform
Tunnel submerging from the montage platform
Floating platform with 4 supporting legs
Arguments in support the floating tunnel
• The future project, based on modern technological capabilities and needs, which, in the successful launch, also includes application in the rest of the world, with the high-tech line for the production of tunnel parts to remain in Estonia and Finland. Worked out know-how and successful patent rights would provide long-term profits.
• Comes with the idea of RailBaltic and makes really possible to finish tunnel construction simultaneously with RailBaltic and to save resorces .
• Our own labour and engineering staff can used and thus earned during the construction and during the operation of the tunnel money will stay here.
• Finland experience and shipyards can be used for floating platform design and building. After successful first project such production can be sold for future projects around the world.
• Investments to the North –East of Estonia will remarkable reduce local unemployment and thus also will reduce national security risks.
• It would support Saaremaa Fix development (a two way road tunnel via Kessulaid; 3,5+ 4,5 km).
Immersed road tunnel (3.5+4.5 km) for Saaremaa fixed connection as additional advantage
Two separated directions 5X5 m,
Wall thickness 0,75 m Displacement for 1m length 75 m³ (11,5x6,5=74,75)
Volume of the concrete 22,25m³(74,75-52,5=22,25m³) for 1m
Weight of the 1 m is 60 t 5m module weight 300 t10m module weight 600t
Price for 1m (500 €/t) 30 000 € 8 km will cost 240 M€
5 X 5 m5 X 5m
ARCHIMEDES BRIDGE !SFT
Thank you!
