KR20110110171A - Method for constructing water barriers and coastal protection - Google Patents

Abstract

The present invention relates to a method for constructing a shield. In this method, in a condition where the sea floor is constructed using floor material, at least at the location of the curtain, the quarry core is provided on the sea floor and a protective layer of stones or concrete blocks is provided. The method is particularly suitable for the construction of liner membranes for relatively deep water.

Description

TECHNOD FOR CONSTRUCTING WATER BARRIERS AND COASTAL PROTECTION}

The present invention relates to a method for constructing a barrier film and coastal protection material such as a breakwater, and a barrier film obtained by the method.

Breakwaters include structures built from relatively hard rocks that are placed on the sea to protect coastal areas. In that the breakwater absorbs an important part of the wave energy of the incoming waves, the protection becomes possible, and the waves arrive in the coastal region in attenuated form. Well-known rockfill breakwaters are generally built from the core of quarry run into an outer heavy protective layer, called the armor layer. The armor layer generally includes larger and heavier rock blocks than the core material. Concrete members are also applied. The rock blocks have a somewhat irregular shape such that the protective layer is sufficiently porous and permeable to the waves. As the wave partially penetrates the protective layer, the wave energy is attenuated.

In addition to the damping waves, breakwaters also protect coastal areas from erosion, caused by the transport of undesirable deposits from coastal areas to the sea. The breakwaters interfere with the natural transport patterns of the sediments, preventing or reducing erosion in coastal areas.

Due to the protective role of the breakwater, regular sand replenishment along the eroded shore is less essential. A disadvantage of known barriers or coastal protection, in particular breakwaters, is that the effect of sand transport along the coast depends on a number of variables such as the length of the breakwater and / or the distance from the shore, for example. At unoptimized ratios, problems arise regularly that can result in undesirable sand transport. Known breakwaters can therefore lead to the formation of deposits in the form of bells (so-called “projections”), for example. Known breakwaters also have room for erosion near the bottom of the breakwater, which weakens the stability of the breakwater.

It is an object of the present invention to provide a method by which a barrier film, in particular a breakwater, can be constructed, which is provided with the same level of protection as known breakwaters, and the problems mentioned above can be at least partly eliminated.

This object is achieved in accordance with the present invention by providing a method for constructing a water repellent film of the type described above, wherein the core of the quarry is at least at the position of the water repellent, provided that the bottom of the water is erected using floor material. run) is provided at the bottom of the seabed and a protective layer of rock or concrete block is provided. According to the present invention, a bottom material or a deposit is supplied to the position of the order film. The landscape is initially unfavorable because the total amount of bottom material gradually increases near the curtain and increases the chance of loss of stability and / or undesirable deposit transport. This expectation is exacerbated by newly supplied floor materials which are generally less stable than floor materials that have already existed for a long time. However, it was surprisingly found that the linings obtained by the process of the present invention were surprisingly stable and resulted in less undesirable deposit transport than expected.

According to the present invention, the order film is obtained such that the total height of the core and the protective layer is reduced as compared with the known order film. Its remarkable advantage is that the barrier film of the present invention can be constructed more economically than the conventional barrier film. The materials of the core and the protective layer are generally expensive to purchase and are also transported by land, which leads to high costs. The insulation film according to the present invention can save cost by using a core material having a reduced volume as compared to the known insulation film at substantially the same insulation film level. Since the amount of material required in the liner film increases rapidly with depth, the present invention is particularly suitable for liner construction for relatively deep water, where relatively deep water is at least 8 meters deep, more preferably at least It is understood to mean water having a depth of 14 meters, most preferably at least 20 meters.

Another advantage of the method according to the invention is that the supply of a portion of the material for the containment membrane is possible in a simple and fast way. Although the supply of the flooring material required to erect the bottom of the sea floor takes place, for example by supplying the flooring material, generally through sand, substantially overland, the flooring material is more preferably near the construction membrane to be constructed. To be dredged in the very neighborhood is recommended. Dredging is a known technique per se and can be performed using, for example, a trailing suction hopper dredger. It includes a suction head, along with a drag head that falls below the water at the back of the hopper dredger until its bottom contact is under its weight effect. Through the forward movement of the hopper dredger, the drag head drags the bottom for dredging, where the soil is loosened and sucked with water through the suction conduit. Preferably, the sucked bottom material can be immediately transported via a transport conduit to the desired location, in particular near the construction membrane.

In a preferred embodiment, the method according to the invention is characterized in that the sea floor is constructed of floor material before the core is provided. A more effective method, and more reliable method, is obtained here. It is therefore possible, for example, to measure the height of the bottom of the constructed seabed before the core is ready. If desired, the built part of the pirate floor may also be compacted or otherwise treated in other ways.

The subsea bottom can in principle be constructed at any height in accordance with the present invention, and the stability of the insulation film is ensured. A barrier film composed of substantially the entire bottom material will generally be too unstable and therefore its function cannot be adequately met. In one preferred embodiment of the method according to the invention, the bottom of the water has an average depth of 20 to 80%, more preferably 30 to 70% and most preferably 40 to 60% at the position of the water curtain. It is built in a reducing height. The order film has the best results in this range.

Particularly stable linings are constructed at depths where the seabed floor does not exceed 50% of the closure depth and more preferably does not exceed 75% of the closure depth and most preferably does not exceed the closure depth. Obtained by means of construction at depth. The closure depth is a term well known to those skilled in the art. When the depth is observed regularly off the coast, a minimum depth is found in which the depth does not change for a predetermined time. This depth is called the closing depth. The closure depth can be determined experimentally or can be derived in a simple manner by the following formula according to the invention:

d ₁ = 1.75 H _{S0 .137} (1)

Where d ₁ represents the closed depth, H _{S0 . 137} is the effective wave height at the position of the containment film. The effective wave height is a wave height that does not exceed up to 12 hours per year and therefore has a maximum probability of occurrence of 0.137%.

The process according to the invention is preferably constructed at a level such that the volume of the material required for the center and protective layers is reduced by 20 to 80% compared to the non-built underlayment, more preferably 30 To 70%, most preferably 40 to 60%. As with the aforementioned type, statistically stable breakwaters generally must be less deformed under wave attack. Therefore, relatively heavy buildings are required. According to the method according to the invention, the order film is lighter per unit volume than the known order films. It is surprising that this has little or no effect on the stability of the curtains. Unprotected sand barriers may not seem very obvious at first. Nature affects such a curtain, transforms it, and will probably flatten it completely over time. The shield according to the invention comprises a lower quantity of weighting material (quartz and protective layer stones) than conventional shields of the same height. Nevertheless, the problems described above rarely arise.

A further preferred embodiment of the method according to the invention is characterized in that the constructed seabed bottom is compacted at least at the position of the curtain. The compaction of the built underwater floor can be carried out, for example, by vibration or by piling-driving at drop weights. It is also possible and advantageous to provide ground improvements for the built underwater floor to make it more stable and to make the barrier even more resistant to earthquakes.

The constructed subsea bottom can in principle be compact at any desired saturation density. Said saturation density can be understood to mean the density of the volume of material substantially saturated with water. The built subsea floor is between 1.6 ton / m ³ and 2.3 ton / m ³ , more preferably between 1.7 ton / m ³ and 2.2 ton / m ³ , most preferably 1.9 ton / m ³ and 2.1 ton It has been found effective to compress to a saturation density between / m ³ .

It is another feature of the present invention that a filter layer is provided between the built underwater floor and the center. This approach enhances geotechnical stability. This reduces soil erosion at the extraction of the barrier, in particular the breakwater. The bottom material is further prevented from moving to the core. The bottom material is in principle less permeable than quarry. Therefore, the movement reduces the porosity of the core. The breakwater action becomes less effective. This embodiment is modified to at least partially avoid this. In some cases the filter layer also allows water to pass through. Relatively permeable linings or breakwaters are likely to deposit sand, especially in sand-rich conditions (waves and currently supplied sand filling the small holes).

The order membrane according to the invention also comprises a plurality of filter layers, which for example take the form of a stone layer between the center and the protective layer. Here a gradual change occurs between the relatively fine and coarse material. If desired, the containment membrane is also provided with a toe construction for the purpose of supporting the protective layer in the inclined direction of the slope, and a crown wall at the top of the containment membrane is provided for walking on it. Done.

Inorganic membranes according to the invention, in particular the breakwaters according to the invention, can be constructed with crest under or above water. The height position of the crest of the breakwater relative to the average water level determines the degree of diffraction as well as the amount of wave energy vanishing in the structure. The greater the allowable wave energy, the less wave loads on the breakwater. Breakwaters with their crests below the water have the advantage that they pass large amounts of wave energy, thereby reducing the load on the breakwater.

Fully impermeable breakwaters reflect wave energy or disperse wave energy in relatively small rock volumes. The breakwaters are generally more heavily loaded. Thus, such breakwaters are heavier.

A more preferred embodiment of the method according to the invention is characterized in that the construction has an inclination, as the underwater floor is built progressively from its natural level to a position near the curtain. This embodiment has the advantage that at least in part the waves lose their energy before they reach the curtain. In addition, model tests occur to a lesser extent of sediment transport to the area between the curtain and the shore. It is advantageous when the height of the building increases at a substantially constant slope in the direction of the curtain. Best results are obtained when the tilt angle in the horizontal direction is between 1: 2 and 1:20, more preferably between 1: 5 and 1:15, and most preferably between 1: 7 and 1:10. . Preferably the sea floor is built progressively from the natural level to a location near the curtain, the construction having an average slope, the average slope comprising one or more horizontal portions. The horizontal portion preferably has a length of two to three times the depth of the building at the location.

In order to support the preferred effect of the inclination, in one preferred embodiment of the present invention, the inclination is provided in a plurality of order films arranged at a mutual distance from each other and substantially aligned in the order film. The crests of the plurality of lining films are preferably placed at an increasing height in the direction of the lining film, provided that the crest heights of the lining films do not exceed that of the lining film.

The present invention will be described in more detail with reference to the accompanying drawings, without limitation.
1 shows a schematic cross-sectional view of a first embodiment of a liner according to the invention.
Fig. 2 shows a schematic cross sectional view of a second embodiment of a liner according to the invention.

Referring to FIG. 1, a water barrier 1 embodied as breakwater, obtained using the method according to the invention, is shown. The embodiment of the illustrated membrane 1 builds a subsea bottom 3, which is present as an externally supplied bottom material 4, at least at the position of the degree membrane 1, and subsequently on the supplied bottom material 4. By placing a core 2 of quarry run, for example by pouring it onto the supplied bottom material 4. The quarry core 2 is provided with a protective layer 5 of about 2 m thick constructed of rocks 6. A filter layer 8 of granular material having a stone size of 5 to 75 mm is provided between the built underwater floor 4 and the core 2. It is likewise possible to apply geotextiles with typical thicknesses between 2 and 5 mm.

In the embodiment shown in FIG. 1, the top of the barrier film protrudes towards the water surface 7, but it is also possible that the top is arranged below the water surface 7 to hide the breakwater for viewing. The underwater bottom, which is 14 m below the water surface 7, can be built, for example using 5 m below the average water surface 7, for example using the method of the invention. The bottom of the sea floor is therefore constructed at a height where the water depth is reduced from -14m to -5m, and therefore about 65%. In this embodiment, the conventional liner provided directly on the bottom of the existing seabed is at least about 14 meters high. The method according to the invention results in the overall height of the center 2 and the protective layer 5 being approximately at least 9 m, which corresponds to a reduced height of about 65%.

When the sea floor 3 is built progressively from its natural level to a position near the curtain 1, the height of the building 4 increases with a substantially constant slope 9 in the direction of the curtain 1. Has an effect. In the example shown, the angle of inclination 10 with respect to the horizontal direction is between 1:10 and 1:20.

The building 4 may extend at a relatively large distance to the sea side (left side in FIG. 1) of the curtain 1. In a preferred embodiment (not shown), the inclination 9 is provided in a plurality of order films arranged substantially in line with the order film 1 and obtained in the same manner as the order film 1. The crests of the linings are then placed at increasing height in the direction of the lining 1 as seen from the sea side, but it does not exceed the crest height of the lining 1.

With reference to FIG. 2, another embodiment of the liner 1 is shown, which can be obtained using the method according to the invention. The embodiment of the illustrated membrane 1 uses at least the bottom material 4 supplied elsewhere at the position of the membrane 1, which is then present while providing the cores 2, 2a, 2b of the quarry therein. Obtained by building the underwater bottom 3, the central portion 2a of the core consists of coarse rock, the right part of which consists of even coarse rocks 2b. The cores 2, 2a, 2b are poured over a number of operations onto the supplied bottom material 4. The cores 2, 2a, 2b are then provided with a protective layer 5 constructed of about 2 m thick and made of rocks 6. A filter layer 8 having a thickness of 5 to 75 mm is provided between the constructed subsea bottom 4 and the core 2. The portions 2a, 2b provide a locally increased porosity in the core layers 2, 2a, 2b, whereby the wave energy is better dispersed locally. This embodiment further comprises a building 4 having two terraces 9a and 9b which are substantially horizontal and two parts 9c and 9d having a slope. This structure has a more preferable effect on the breakwater action and the stability of the insulation film 1.

The invention is in no way limited to the above-described exemplary embodiments, and many variations are possible within the scope of the appended claims.

Claims (15)

In the method of construction of the curtain,
A condition in which a quarry core is disposed on the bottom of the seabed and provided with a protective layer of stones or concrete blocks, at least in the condition that the bottom of the seabed is constructed from the bottom material at the location of the water curtain. The method of claim 1,
And said subsea bottom is constructed of floor material prior to said core placement. The method according to claim 1 or 2,
And the bottom of the seabed is constructed at a height such that the average depth at the position of the curtain is reduced by 20 to 80%. The method according to any one of the preceding claims,
And the bottom of the seabed is constructed with a depth not exceeding 50% of the closure depth. The method of claim 4, wherein
And the bottom of the seabed is constructed with a water depth not exceeding the closing depth. The method according to any one of the preceding claims,
The undersea floor is a construction method, characterized in that the volume of the material required for the center and the protective layer is built in a level that is reduced by 20 to 80% compared to the non-building bottom curtain. The method according to any one of the preceding claims,
And the built-in seabed bottom is compact at least at the position of the curtain. The method of claim 7, wherein
The constructed seafloor bottom is compacted with a saturation density between 1.6 ton / m ³ and 2.3 ton / m ³ . The method according to any one of the preceding claims,
And a filter layer is disposed between the constructed seafloor bottom and the center. The method according to any one of the preceding claims,
And the construction is inclined such that the sea floor is gradually built from its natural water level to a position near the curtain. The method of claim 10,
And the height of the building increases by a substantially constant slope in the direction of the curtain. The method of claim 11,
The angle of inclination of the horizontal direction is between 1: 2 and 1:20, more preferably between 1: 5 and 1:15, and most preferably between 1: 7 and 1:10. Way. The method according to any one of claims 1 to 9,
And wherein said subsea floor is built progressively from its natural water level to a position near said curtain, said construction having an average slope, said average slope comprising one or more substantially horizontal portions. 14. The method according to any one of claims 10 to 13,
And the inclination is provided in the plurality of order films placed substantially horizontally on the order film. The method of claim 14,
The crests of the plurality of order films are arranged at increasing heights, but the method of claim 6, characterized in that does not exceed the height of the crest of the order.

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