WO2014045085A1

WO2014045085A1 - Protection against tsunami and high sea waves

Info

Publication number: WO2014045085A1
Application number: PCT/IB2012/056613
Authority: WO
Inventors: Hans Scheel
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-09-19
Filing date: 2012-11-22
Publication date: 2014-03-27
Anticipated expiration: 2015-03-19

Description

Protection against Tsunami and high sea waves

1. Field of Invention

The present invention relates to the protection against shock waves causing Tsunami sea waves, and against high sea waves and flooding from storms.

2. Cross-references to Related Applications

The present application claims the benefit of the priorities of the following patent applications:

- PCT/IB2012/054970 filed on September 19, 2012 in the name of Hans SCHEEL

- PCT/IB2012/054983 filed on September 20, 2012 in the name of Hans SCHEEL

- PCT/IB2012/055177 filed on September 28, 2012 in the name of Hans SCHEEL

- PCT/IB2012/055378 filed on October 5, 2012 in the name of Hans SCHEEL

The entire disclosure of these applications is incorporated herein by reference.

3. Background

Many coastal areas have the risk of high Tsunami sea waves which may cause the death of coastal inhabitants and huge damage to cities and industrial and cultural buildings and infrastructure. The largest Tsunami catastrophes have been in the year 1755 Lisbon with 60^{^}000 casualties, 1883 Krakatau vulcano 36^{^}000, 1896 Meiji- Sanriko/Japan 26^{^}000, 1908 Messina/Italy >75 000, 1933 Showa-Sanriko 3 000, 2004 Sumatra and 8 countries 23Γ000, and 11.3.2011 Tohoku, Japan with >19 000 casualties and the Fukushima catastrophe. According to Bryant (2008) many large cities like Tokyo and New York and hundreds of km coastline are threatened with future Tsunami.

Tsunami sea waves or seismic sea waves up to 38m height are formed when the pressure waves of earthquakes or of landslides reach the decreasing water depth at the coast. The long wavelength of the pressure wave is then reduced and compensated by increased amplitude, or in other words the kinetic energy of the pressure wave is transformed to potential energy by increasing the height of the Tsunami sea wave. Human observations of wave height up to 38m have been confirmed by computer simulations. General descriptions of Tsunamis have been published by Bryant (2008) and by Murty (1977), and the physics of Tsunamis by

Levin and Nosov (2009).

Expensive Tsunami warning systems have been developed which often are too late for coastal inhabitants and which anyhow cannot prevent huge material, housing and infrastructure damages.

Breakwaters and dams are widely applied but give only marginal protection as shown in Kamaishi, Iwate Prefecture, Japan. The world's deepest breakwater structure constructed during 31 years at the cost of 1.5 billion USD has been celebrated on September 27, 2010 for the Guiness Book of World Records. However, with its length of 1960m and depth of 63m it could not protect the harbour and city of Kamaishi, so that the March 2011 Earthquake and Tsunami killed about 1000 people and partially destroyed the breakwater. In a PhD thesis A. Strusinska (2010, 2011) simulated the development of Tsunami sea waves using the Coulwave programme of Lynett (2002; Lynett and Liu 2002) and reviewed the protection attempts trying to reduce the effect of the already formed Tsunami sea waves.

Deep-sea construction using conventional concrete technology is in principle possible in view of behavior studies of concrete in marine environment (Al-Amoudi 2002; Mehta 1991; Stark 1995). However the challenge increases significantly with increasing depth of the sea.

The principle of the invention is shown with a cross section in Fig.l with the pressure waves from earthquakes or landslides reflected at the stable vertical wall and with release of some pressure energy by upward motion of water in front of the barrier. The vertical submerged wall is facing reduced shear flow and no impact from high sea waves, whereas the vertical front of the dike or levee is protected above sea level by hanging inclined/triangular structures which can be replaced.

4. General Description of the Invention

The present invention provides vertical stable walls at modest costs and at relatively high production rates.

To this effect, it relates to a protection barrier as defined in the claims.

Fig. 1 represents a schematic cross section of a vertical barrier (e.g. a Tsunami barrier) reflecting the pressure waves from earthquakes or landslides. The space towards the coasts is filled in order to gain new land. In a preferred embodiment, net structures, preferably in steel, like fences are lowered into the sea by assistance of weights (for instance of hanging anchors) together with steel anchors which in horizontal position fix the fence in vertical position after rocks have been deposited. Fig. 2 shows a schematic cross section of a pontoon for inserting the fence from a roll.

A variety of high- strength steel fences are produced by Geobrugg AG, Romanshorn, Switzerland (Geobrugg 2012). This company has shown that their special fences have a combination of high strength and elasticity so that they can stop falling rocks and thus protect mountain roads and railroads. Typical fence designs are shown in Fig. 3. a to 3.C The weights of square meter are 0.65 , 1.3 , and between 4.5 and 10 kg/m for 3. a, 3.b and 3.c, respectively. Their rolls of 7m width and up to 100m length have weights (in air) between 18 tons and more than 150 tons for 40 rolls corresponding to 4km total length, depending on wire thickness and steel net structure. If weight is a problem for the pontoons or for the mechanics or for the upper fraction of the steel net, then temporary relief can be arranged by fixing for example rafts or boats on the seaward side to the steel-fence, or by attaching low- density material to the fence. This improvisation can be removed after the rocks on the landward side have fixed the anchors and thus distribute the weight along the steel fence as discussed below.

All steel components are produced from saltwater-corrosion-resistant steel, for example chromium- and molybdenum-containing low-carbon-steels with European numbers 1.4429 (ASTM 316LN), 1.4462, 1.4404 or 1.4571 (V4A). All metal alloys should have the same or similar composition in order to prevent electrolytic reactions and corrosion at the connecting points. Furthermore, long-time corrosion may be prevented by coating all metal parts with special corrosion-resistant paint or by an elastic polymer, or by covering the steel fence structure seaward by concrete.

The specific fence structure and the thickness of the wires and of the steel ropes have to match the strength and elasticity requirements depending on the total height of the fence-rock structure, the size and shape of rocks, the number and structure of horizontal anchors, and the risk of earthquakes. Also a variation of the type of fence along the height or the length of the barrier may fulfil local requirements or reduce the weight problem.

When the lowest fence and the lowest anchors have reached the bottom of the sea or the desired position on the sea-ground they are fixed there to the ground by anchors, by steel bars and/or by concrete foundations. Before this procedure the sea- ground is cleaned from sand and soft material by high-pressure water jets arriving through pipes or produced locally by submerged compressors or fans, and steep slopes may be removed by excavation. Now rocks of specified size and sharp edges are inserted from sea level on the landward side so that they cover and fix the horizontal anchors and thus also the steel fence which is thus held in more or less vertical position. The rocks are washed before so that the clear view allows to control the process by strong illumination and video cameras and/or by divers or by diving bells. The rocks will settle with time, especially assisted by man-made vibrations (explosions) or by vibrations caused by earthquakes, typically 2000 per year in Japan.

Furthermore the rocks are fixed by gravel and/or sand which is inserted periodically when the rock layer has grown to a layer of say 2m to 5m. In order to prevent major movements of the rocks, more or less horizontal steel fences can be deposited about every 20m to 50m rock thickness.

For the highest degree of Tsunami protection the steel fence extends down into the sea to the bottom of the sea at typically 4km depth in the pacific ocean. If the fence is delivered in rolls of 100m length, this requires 40 rolls. The upper end of the first roll is on the pontoon or ship connected to the lower end of the second roll to be inserted into the sea, and after this the upper end of the second roll is connected with the lower end of the third roll, and so on. The delivery ships or pontoons are arranged in a horizontal line following the depth level of the sea or following the coast-line, and this work requires relatively quiet sea. An alternative approach could be used to produce the steel fences directly on the pontoon with steel wires to be supplied, or to deliver the fence rolls over long temporary bridges from the coast.

The horizontal connection of the steel fences can be achieved above sea level by means of steel ropes or clamps or alternatively their side holders can glide down along steel beams. This is arranged on the ships or pontoons, but it is a critical procedure. It would be easier when, together with the fences, a chain of steel beams is inserted seaward just in front of two neighboring fences, and these steel beams have side-arms corresponding to the openings of the fences respectively on the size of the inserted rocks. These side-arms not only prevent the rocks to fall seaside, but they also contain spines in landward direction which enter openings of the steel fences on both sides and thus connect two parallel horizontal fences: this allows large distance tolerances between parallel horizontal fences. The vertical steel beams are also equipped with horizontal anchors of 2m to 20m length to fix the steel fences in vertical position by subsequent rock deposition, so that the anchors need not to be fixed directly to the steel fences. These steel beams with side-arms, spines and anchors are shown in Fig. 4. a, 4.b and 4.c.

The spines can be replaced by automatic clamps which lock to the fence upon contact, when mechanically or magnetically pulled in landward direction.

The invention will be better understood in the following chapters, by way of examples illustrated by some figures.

List of figures figure 1: Schematic cross section of a vertical barrier (e.g. a Tsunami barrier) reflecting the pressure waves and gaining new land figure 2: Schematic cross section of a pontoon for inserting the fence from a roll

figure 3: Typical fence designs

figure 4: Steel beams with side-arms, spines and anchors (a. and b. side views, c. top view)

figure 5: Inclined triangular concrete structures (cross sections)

figure 6: Tsunami barrier extending to the bottom of the sea, with a gap for navigation and for preserving beaches (schematic cross section) figure 7: Tsunami barrier in simple terrace structure, with reduced fill

material and gaining new land (schematic cross section)

figure 8: Double-fence barrier, lowered into the sea down to the bottom of the sea and filled with washed rocks and gravel (schematic cross section)

figure 9: Double-fence barrier with concrete wall and hanging triangular

curved structure, space between the double-fence and the coast can be filled with rocks and other materials to gain new land (schematic cross section)

figure 10: Double-fence tube filled with rocks to protect platform pillars, wind- power plants, bridge pillars (a. top view, b. cross section)

figure 11: Vertical excavated coast as Tsunami barrier, schematic cross section figure 12: Vertical concrete wall (30) as dike stabilized by heavy rocks (45), schematic cross section

figure 13: Triangular structure of Fig. 5. a mounted onto the concrete wall (30) of Fig. 12, cross section

figure 14: Triangular structure from Fig. 5.b mounted onto the concrete basic wall (30) of Fig.12, cross section

figure 15: Vertical dike with steel fence between steel beams, mechanically stabilized by heavy mass (45), schematic cross section figure 16: Flexible steel fence (48) fixed vertically in front of the pillars (47) of the oilrig (off-shore platform) 46, for example fixed on at least an upper ring 50 (circle or rail) and at least a lower ring 51 (circle or rail), (top view)

figure 17: Steel frame (52) around the steel net structure 48 (side view) figure 18: Wave- splitting structure (named wave deflector) with the tip (54) in two positions with "vertical" side walls in streamline shape, (in front of the oil-rig) which can be adjusted against the normal or the actual wave front and is fixed on the sea floor (55) (top view)

5. Specific Realization Aspects of Steel-fence Barriers

The horizontal extension of the barrier will at least be several km depending on the length of the coastline or harbour to be protected. For protection of the Tokyo bay a length of at least 15km is required, and the protection of the coast between Iwaki and Shiogama including Sendai, Sendai Airport and Fukushima requires at least 150km Tsunami barrier length.

When the Tsunami barrier reaches the sea level, the area between the barrier and the coast can be filled with rocks, gravel, rubble and so on with a soil layer on top so that new land can be gained, see Fig. 1. In this case a vertical barrier of concrete of at least 5m height should be built on top of the Tsunami fence barrier to protect the new land from partial Tsunami waves and from high sea waves caused by storms. The thickness of this concrete wall should be at least lm at the sea and at least 50cm along rivers. The top of this concrete wall may have steel beams so that later heightening may be facilitated and that inclined structures with inclination towards sea may be hung onto these concrete walls to reduce overthro thing, reduce erosion of the concrete wall, and allowing replacement. Two such inclined concrete structures are shown in Fig. 5. Fig. 5a shows a structure with a straight inclination and Fig. 5 b shows a structure with an upper curvature. A heightening of the concrete walls may also be required in case the whole fence-rock structure should sink (as in the case of Kansai airport), or that the sea level is increasing from climate change, or that higher sea waves from heavy storms are expected. A service road along these vertical concrete walls allows transport, repair, and access for the public.

The value of this new land may largely compensate the construction costs of the Tsunami barrier. These costs consist mainly of transport and excavation charges including specialized fence-delivering pontoons, whereas the fences made of special saltwater-corrosion-resistant steel cost 20 to 100 USD per m without installation. The overall surface topology and the local roughness of the fence-rock structure determine the reflectivity of the pressure waves. This can be adjusted by zigzag or ondulated structures of the Tsunami barrier, whereas the rough fence-rock structure can be flattened for instance by concrete or an elastic polymer in order to enhance reflectivity. These reflected pressure waves may harm opposite coasts on the other side of the ocean or islands. A slight downward inclination from vertical should be applied to reflect the pressure wave for example at the north-east coast of Honshu/Japan down into the Japan trench, or the inclination should be slightly upward to transform the kinetic energy of the pressure wave into potential energy by formation of dispersed sea waves moving away from the coast.

As mentioned above the Tsunami barriers should ideally extend to the bottom of the sea, which in Pacific ocean is typically 4km deep, in order to achieve full reflectivity of the pressure waves. However, in most cases compromises will be necessary to take into account the costs and the timeliness / delivery times with the disadvantage of reduced Tsunami protection. Furthermore the total height will be reduced when the Tsunami barrier has to end for example 5m to 50m below sea level at low tide for navigation or for preserving beaches and harbours, as shown in Fig. 6.

A simple terrace structure requires less rock fill material, still allows to gain new land, and therefore may be preferred on certain coasts, see Fig. 7. This would also become important in case the epicenter of the earthquake would be near to the coast and thus between two steps of the terrace.

6. Advantages of Double-fence Barriers

An alternative to minimize the amount of rock fill material uses two parallel fences (31,32), closed at the bottom, with horizontal separation distances towards the coast between lm and more than 20m established by distance holders (33). This double- fence basket is lowered into the sea down to the bottom of the sea and filled with washed rocks and gravel, see Fig. 8. The thickness of these double-fence walls is determined by the required stability, with Tsunami shock waves needing a thickness of at least 3m. These double-fence rock structures of many km length are flexible at the bottom and therefore can match the local topology of the sea-ground after this has been cleaned by high-pressure water jets as described before. These baskets are closed at their horizontal ends. Also in this case the space between the double-fence and the coast can be filled with rocks and other materials (5) to gain new land, as shown in Fig. 9, and this heavy mass gives further stabilization against Tsunami shock waves. As discussed above, concrete walls above sea level with hanging triangular structures will prevent overtopping of sea waves and reduce the splashing over of the lifted sea water from reflected Tsunami pressure waves. Steel beams are used both for later heightening of the concrete walls and for hanging the triangular structures. The double-fence baskets filled with rocks can also be pre-fabricated on the coast and then inserted and connected in the sea.

Double-fence barriers may also be used in annular tube structures for offshore platforms and wind-power plants, as shown on figures 10. a and lO.b. Double-wall tube structures with rocks (59) inserted between the inner (61) and the outer (62) tube extending above sea level protect the central pillars (58) of offshore platforms or of wind-power plants from Tsunami pressure waves, Tsunami sea waves, and from high sea-waves caused by storms. The shape of the structure/pillar to be protected can be circular, but it can have any other cross section like square, oval, rectangular, triangular etc.

Fig.10. a shows the top view and Fig.lO.b a vertical cross section of such a double- tube structure of which the outer and the inner tube are connected and thus closed at the bottom. The construction is done in analogy to the Tsunami barrier construction.

The first double-fence unit to be inserted into the sea has the largest circumference

( normally at the bottom of the pillar). The inner fence is kept apart from the outer fence by distance holders or by small vertical walls (60). This fence unit is then connected on the supply pontoon /ship (by using clamps, steel ropes or other means) to the next double- fence section to be inserted, and so on. This annular structure is arranged when the platform pillar or the stand of the wind-power plant have only partially been raised. However, also existing pillars can be protected by producing the double-fence-rock structure on site. This alternative method to produce the double-fence protection tube is to wind long fences from rolls around the pillar in a screw fashion, with distance holders to keep the two fences apart, and continuously connect the lower section with the upper section by clamps, steel ropes, or other means.

Cleaned rocks can be inserted from top after the lowest double-fence section has reached the sea floor.

The height of the protection tube and the distance between inner and outer fence, and thus the outer diameter and the mass including the filled-in rocks, depends on the expected highest sea waves. In most cases the horizontal distance between the fences will be in the range lm to 5m. The inner fence will be fixed to the pillar, or a buffer is installed around the pillar to prevent mechanical damage from the steel net and the rocks of which many corners may be outside the inner fence surface.

The upper rim of the outer fence should have warning signals or signal lights for navigation (the same as for the Tsunami barriers ending below sea level).

An alternative vertical protection can be established directly at the coast by excavation to achieve a deep vertical wall (Fig. 11) to reflect the Tsunami shock waves, and the excavated rock material used to stabilize the nearby fence barrier or basket barrier.

Coastline Constructions

In another embodiment the invention includes seawards oriented stable vertical protection walls which significantly reduce the total shear and impact from the seawaves and thus provide increased stability and lifetime. The walls, extending above sea level, reflect the sea waves, and the reflected waves reduce the power of the oncoming waves. The height of the walls has to be higher than the highest expected sea wave level. The seawards inclination angle of hanging triangular structures prevents or at least reduces overtopping and splashing of seawater towards the land, especially when an upper curvature is provided. The walls according to the invention offer an efficient alternative to existing dikes which are usually defined with slopes on both sides, i.e. sea side and land side, which cover large land areas and which provide in many cases insufficient stability leading to catastrophic flooding.

7.1 Example 1 : Vertical Concrete Wall with Hanging Triangular Structure against Sea Waves

Basic walls according to one embodiment of the invention are schematically shown in Fig. 12.

In this embodiment, the walls (30) are perpendicular with respect to the surface of the sea (1), i.e. their inclination is 0°, and extend above sea level. The walls are preferably built from steel-enforced concrete (23) of at least 1 m thickness against the sea (1) and at least 50 cm thickness along the rivers inside the land. The highest density of steel beams is towards the sea and below the surface of the walls for maximized stability and for repair of eroded wall surfaces. These walls are deeply anchored in the sea floor or in the ground by a foundation of concrete and by means of a steel beam fixation (7) and stabilized in direction land (continental) by heavy dense masses (45) consisting of rocks, gravel, sand, rubble and soil of present dike material. The actual height along the coasts in general should be higher than the highest expected sea waves, along the North Sea coasts it should be 8 m to 10 m, but steel rods (22) and the surface morphology of the concrete wall (30) should allow to increase the height with increasing sea level and higher expected sea waves caused by storms.

Like the state-of-the-art dikes the walls according to the invention may extend over many kilometres along the coast.

7.2 Example 2 : Triangular Structures

As discussed previously, the walls may be inclined with respect to the surface of the sea.

Alternatively, the basic walls may be perpendicular with respect to the surface of the sea but additional elements showing an inclined face may be hung to the basic walls, the general structure being then inclined with respect to the surface of the sea.

The second embodiment presented below is characterized by the use of such additional elements. The inclination is achieved by triangular structures, which are hanged onto the basic vertical walls. Two examples of such triangular structures are shown in Fig. 5.

Fig. 5. a illustrates a triangular structure which has a straight inclination (19) only corresponding to a tilting angle; and

Fig. 5.b shows a second triangular structure with a straight inclination (19) and an upper curvature (20). Fig. 13 shows the triangular structure of Fig. 5. a mounted onto the basic wall (30) of Fig. 12.

Fig. 14 shows the triangular structure from Fig. 5.b mounted onto the concrete basic wall (30) of Fig.12.

The optimum tilting angle can be determined theoretically, experimentally, and by computer simulation. However, for practical reasons and weight limitation, the chosen angle is preferably between 10 degrees and 15 degrees with respect to the vertical direction. For instance, an angle of 11.3 degrees and a length of 5 m downward, a concrete structure of 2 m length would have a weight of about 12.5 tons. These triangular structures have to be moved on the service road 8 and lowered onto the vertical concrete wall. These triangular structures have the advantages that a) They protect the basic vertical wall from erosion;

b) They can be replaced to change the tilting angle or for repair;

c) They can be curved outward on the upper part so that overtopping of highest waves can be minimized;

d) They can be replaced to test different construction designs and materials; and

e) They can be used again when the vertical concrete wall is heightened in future.

Concrete is used for the high compressive strength of concrete and steel for the high tensile strength of steel. The replacement possibility allows to test alternative construction materials and material combinations, for example partially fused recycled glass or composite plastic with protection steel plate, or to use hollow structures or wood to reduce the weight: the decision depends on timeliness, lifetime experience, and on local resources and knowhow.

A road (8) along the top of the wall allows control, service, repair of the walls, transport of the triangle structures, and also public traffic, for instance by bikes.

The construction and maintenance costs of the concrete walls according to the invention offer an improved stability and lifetime and further that much less land area is occupied (perhaps less than 50 %) compared to conventional dikes with seaward slopes. New land can be gained if these new dikes are built on the seaward side of present dikes, and when these old dikes are removed or flattened.

7.3 Example 3 : Vertical Wall Construction

In another embodiment of the invention vertical wall construction is shown in fig. 15.

This wall construction comprises flexible steel nets (48) made from saltwater- corrosion-resistant steel and which are vertically or slightly inclined fixed steeply in the ground by means of the steel beam fixation (7, 52) and/or concrete foundations and with angle fixations (holders) towards landside and / or seaside (not shown in the figure). The landward side of the steel nets (48) is stabilized by anchors as described above, and by rocks and heavy dense masses (45) consisting of gravel, sand, rubble and soil of present dike material as given above for the concrete walls of fig. 12. On the landward side of the steel net a dense sheet of steel or hardened composite plastic or textile or other material is arranged to prevent entering of seawater into the heavy masses (45). This sheet can also be mounted at the seaward side of the steel net to facilitate cleaning from algae or other attached material. The heightening (52) of these vertical walls (48) and the road (8) are as described above for fig. 12. For urgent protection the steel fences (48) are fixed to the ground (2) on the seaside of present dikes and laid over the dikes for their temporary stabilization followed by successive lifting the upper part of the fences (48) to form the vertical wall, by establishing the landward fixations, and by following filling the slope landwards with heavy masses (45). Furthermore the flexible steel net structures allow to arrange a tilting angle and a curvature towards the sea with advantages as discussed above. The steel net structures are arranged in horizontal sections of for instance 3m to 10m length so that these sections can be replaced for repair or cleaning or surface treatment. . Sea-based Constructions 8.1 Example 4: Oilrig Protection

The heavy sea-waves are also a risk for the oilrigs, the offshore platforms for oil and gas production of which there are more than 500 with 7000 workers in total in the North Sea and thousands of oilrigs worldwide. In 1980, 123 workers were killed when "Kielland" sank during a heavy storm in front of Norway coast. The pillars of the islands in the North Sea are typically designed to withstand waves up to 20 m, but have a limited lifetime and are ageing with the permanent attacks of the waves. In future the risks are raising with increasing extreme weathers like hurricanes, typhoons and in some areas also from Tsunami- waves.

In this example, the invention includes "vertical" or nearly vertical walls which split oncoming waves to move around the offshore platform whereby these walls are simply constructed from steel nets (fences), or as an alternative in the form of floating wave deflectors in streamline shape with solid "vertical" walls.

The flexible steel fence (48) fixed vertically in front of the pillars (47) of the oilrig (offshore platform) 46, for example fixed on at least an upper ring (50) (circle or rail) and at least a lower ring 51 (circle or rail) as shown in the top view in Fig.16, reduces the risk of catastrophes, especially when the steel fence (48) in streamline design is facing the direction of the most common wave direction (not shown in Fig. 16). The steel net structure (48) may be rigidified by means of steel bars (52) that are mounted for example as a frame around the steel net structure as shown in the side view Fig.17.

The position of the steel-net structure shown in Fig. 16 can be moved in both horizontal directions as indicated by arrows. Furthermore this structure is fixed (anchored) by for example chains or steel ropes (7) to the seafloor/ground (in Western or North-western directions in the North Sea) against the arriving storms and their waves. The directions of the chains or steel ropes (7) can be adjusted to follow the direction of the streamline steel net structures towards the direction of the normally or actually arriving waves. The upper rim of the steel nets is fixed by means of steel rings (50, 51) to the pillars (47) and to the offshore platform (46). Buffers between the pillars and the steel net prevent mechanical scratching of the pillars. The fence structure and the lower ring (51) have an opening (49) on the backside of the streamline tip permitting supply and service ships (not shown in Fig. 16) to approach the oilrig (46). The height of the steel fence (48) extends from sea level up to the rig platform, typically more than 30 m. It is much easier and quicker to install steel nets than fabrication of any solid concrete structure. The steel net is mounted in transportable sections which are connected on site. The opening of the steel net structure will determine the local degree of reflectivity and weakening of the waves. The major costs of such protection networks will be installation, whereas nets from saltwater-corrosion-resistent steel material costs are presently 20 to 100 CHF per m².

The rotatable net structure allows to adjust the streamline tip against the actual wave front to optimize the "splitting" of the waves. The tip of the flexible streamline net can in case of storm warning be moved in the actually observed or detected direction of the wave front.

An alternative to the surrounding steel net structure is a wave- splitting structure (named wave deflector) with "vertical" side walls in streamline shape, (in front of the oil-rig) which can be adjusted against the normal or the actual wave front, as shown in Fig. 18 with two positions. The backside of the wave deflector, facing the oil-rig, is fixed on two stable steel rings or rails (56, 57), an upper and a lower ring with their centre in the middle of the oil-rig. The rings are open to the lee side (49) of the oil-rig for supply ships. The front side of the wave deflector with the tip (54) is fixed by chains or steel ropes (55) to the seafloor and by approximately horizontal saltwater-corrosion-resistant steel bars fixed to the pillars of the offshore platform (not shown in the figure). This fixation is so solid that highest waves cannot lift the wave deflector or change its orientation. The chains or steel ropes to the two or more fixation points on the seafloor can be moved in order to adjust the direction of the wave deflector, or alternatively, the fixation points are distant, so that the angle of the wave deflector is adjusted by the position on the two rings, or alternatively, the angle of the horizontal steel bars can be adjusted. An alternative consists of a drive assembly in the wave deflector which moves it in the desired direction. The wave deflector has stable vertical or slightly inclined side walls with streamline towards the tip 54, so that oncoming waves are split and guided around the oil-rig. The mechanical strength is very high at relatively low mean density so that the load on the rings is much below (ca. 20%) their maximum load. The mean density and the displacement of the wave deflector are adjusted so that it floats on sea water. The wave deflector can be full body with steel walls and light-weight interior, or it can be a hollow structure with side walls kept in position by steel bars. The construction uses experiences from ship construction. References

- O.S.B. Al-Amoudi, "Durability of plain and blended cements in marine environments", Advances in Cement Research 14(2002)89-100.

- N.W.H. Allsop, editor, "Coastlines, Structures and Breakwaters 2005", Institution of Civil Engineers, Thomas Telford Ltd., London 2005.

- E. Bryant, "Tsunami, the underrated Hazard", second edition, Springer ISBN 978- 3-540-74273-9, Praxis Publishing Ltd, Chichester UK 2008.

- Geobrugg (2012) AG, Geohazard Solutions, 8590 Romanshorn, Switzerland, www.geobrugg.com

- B. Levin and M. Nosov, "Physics of Tsunamis", translation, Springer 2009, ISBN 978-1-4020-8855-1, e-ISBN 978-1-4020-8856-8.

- P.J. Lynett, "A multi-layer approach to modelling generation, propagation, and interaction of water waves", Ph.D. thesis, Cornell University, USA, http ://ceprof s . tamu . edu/plynett/c v/index .html .

- P. Lynett and P.L.-F. Liu, "A Numerical Study of Submarine-landslide-generated waves and run-up", Philos. Trans. Roy. Soc. A458(2002)2885-2910.

- P.K. Mehta, "Concrete in the Marine Environment", Elsevier Applied Science, New York 1991.

- T.S. Murty, "Seismic Sea Waves: Tsunamis", Bulletin 198, Department of Fisheries and the Environment, Ottawa, Canada 1977.

- H.J. Scheel 2012a, "Structures and Methods for Protection against Tsunami-waves and high Sea-waves caused by Storms", WIPO PCT/IB2012/054543 of September 03, 2012.

- H.J. Scheel 2012b, "Protection of Tsunami Shock Waves or Similar Natural Disasters and Acquisition of New Land", WIPO PCT/IB2012/054970 of September 19, 2012.

H.J. Scheel 2012c, "Construction of Tsunami Barriers", WIPO PCT/IB2012/055177 of September 28, 2012.

- H.J. Scheel 2012d, "Stabilizing System for Dikes, Levees and Oilrigs", WIPO PCT/IB2012/054983 of September 20, 2012.

- H.J. Scheel and R. Hauser Scheel, "Construction of Deep-sea Walls", WIPO PCT/IB2012/055378 of October 05, 2012.

- D. Stark, "Long-time Performance of Concrete in a Seawater Exposure", PCA R&D Serial No. 2004, 1995.

- A.Strusinska, "Hydraulic performance of an impermeable submerged structure for Tsunami damping", PhD thesis 2010, published by ibidem- Verlag Stuttgart, Germany 2011, ISBN- 13: 978-3-8382-0212-9.

Claims

1. Barrier against shock waves such as Tsunami and/or against high sea waves comprising a wall, of which the lowest end is adapted to be fixed on the sea floor, said wall being furthermore designed to be stabilized in a substantially vertical position.

2. Barrier according to claim 1 wherein said wall is a fence stabilized landward by rocks, concrete blocks or other solid bodies.

3. Barrier according to claim 2 comprising several fences horizontally and vertically interconnected to form a large continuous surface.

4. Barrier according to claim 2 or 3 wherein said fence(s) is/are made of steel.

5. Barrier according to anyone of the previous claims 2 to 4 comprising anchors which are fixed to said fence(s) and which are held horizontally and adapted to be fixed by rocks or concrete blocks.

6. Barrier according to anyone of the previous claims 2 to 5 comprising two substantially parallel fences connected at the bottom and thus forming a fence basket adapted to be filled by rocks and/or similar materials, and with distance holders to keep the parallel fences apart.

7. Barrier according to anyone of the previous claims 2 to 6 comprising a chain of beams with side-arms, spines and anchors to connect neighbouring fences and to provide the horizontal anchors to stabilize the vertical fences by rocks.

8. Barrier according to anyone of the previous claims 2 to 7 wherein said fence(s) is/are coated or filled in by a salt-water resistant elastic polymer like a natural or a synthetic rubber, poly-urethane, or by concrete.

9. Barrier according to anyone of the previous claims 2 to 8 being designed to emerge above the sea level in a way as to protect constructions such as offshore platforms or wind power plants.

10. Barrier according to anyone of the previous claims where the surface topology and structure and the inclination from vertical are adjusted to reduce the harmful effect of reflected pressure waves on opposite coasts.

11. Barrier according to claim 1 of at least lm thickness at the sea and at least 50 cm thickness along rivers, fixed by concrete foundation in the sea floor or in the ground and extending at least 4 m above the sea level to replace conventional dikes, with vertical steel beams for later heightening and for hanging triangular long structures, preferably of concrete, of 1 m to more than 5 m horizontal length to protect the concrete wall, and to be replaced when eroded or damaged, said barrier being stabilized landward by heavy masses to withstand sea waves from heaviest storms and recover at the same time land surface.

12. Barrier according to anyone of the previous claims comprising a floating wave deflector.

13. Barrier according to anyone of the previous claims comprising a sequence of submerged walls in terrace structure.

14. Method for constructing a barrier as defined in anyone of the previous claims 1 to 10 and 13, said method comprising the following steps:

- Lowering of fence(s) with anchors into the sea by assistance of weights,

- Horizontally fixing said anchors by rocks or concrete blocks inserted from above,

- Filling the coast side of said fence with rocks and/or similar materials and a top soil layer to gain new land.

15. Use of the circular double-fence tube barrier filled with rocks or other solids as defined in claims 6 and 7 for protecting bridge pillars, offshore platforms, wind power plants, light-towers, Tsunami warning systems and other submarine buildings.