Method and device for acoustic insulation

Abstract

The invention relates to a noise protection device (1) for underwater pile driving, comprising at least one pipe (10) that can be fixed to the seabed (2) and which has a plurality of boreholes (105), and at least one winding device (15) with a drum (152) onto which the pipe (10) can be wound, wherein a compressed air connection for the pipe (10) is provided inside the drum (152) of the winding device (15). The invention further relates to a winding device of such a noise protection device, a ship equipped therewith, and a method for noise protection.

Description

[0001] The invention relates to a noise-reducing device for underwater pile driving, comprising at least one pipe that can be fixed to the seabed and has a plurality of boreholes, and at least one compressor with which compressed air can be introduced into the pipe so that it can exit through the boreholes. The invention further relates to a method for reducing the transmission of sound in a liquid, comprising the following steps: deploying a pipe on the seabed that encircles the sound source and is provided with boreholes, and introducing compressed air into the pipe so that it exits through the boreholes.

[0002] Such devices and methods can be used for noise reduction when installing cylindrical piles into the seabed. These piles can be used to anchor monopile, tripod, triplepile, or jacket structures, upon which structures such as wind measurement masts, wind turbines, drilling platforms, or substations can be founded in offshore areas.

[0003] The aforementioned foundation structures can be largely prefabricated on land, allowing for quick and easy installation on site, often under challenging weather conditions. However, a disadvantage is the need for heavy pile-driving equipment, which generates a high noise level, for example, exceeding 130 dB. Such noise levels can be harmful to marine life.

[0004] From DE 10 2004 043 128 A1, it is known to convey compressed air through a pipe system surrounding the pile driving site, which can then escape through boreholes in the pipes. However, since the pipe has considerable buoyancy due to being filled with air, this measure is complex to implement. For example, the pipe can be anchored to the seabed by divers to prevent it from floating during operation. After completion of the construction work, the pipe must either be abandoned or detached from the seabed by divers again. Alternatively, the pipe can be weighted down with external weights, but this makes it more difficult to handle.

[0005] From CA 2174149 A1 a hose reel for an air hose is known which makes it possible to quickly wind and unwind the air hose of a machine tool under pressure at various directional angles from the mounting position.

[0006] JP 2000-302199 A discloses a hose reel for a pneumatic tool, which allows work to begin immediately after the hose reel has been moved to a work site and connected to an air supply. Furthermore, the hose is quickly replaceable by means of a push-fit connector on an outer circumferential surface of the reel.

[0007] WO 91 / 07546 A1 shows a floating oil boom which has an air-absorbing buoyancy element and a curtain suspended from the buoyancy element.

[0008] The invention is therefore based on the objective of providing a device and a method for underwater pile driving which combines good sound insulation with low equipment costs, so that the sound insulation measures can be carried out quickly and easily.

[0009] The problem is solved by a soundproofing device according to claim 1, a ship according to claim 6 and a method according to claim 7.

[0010] According to the invention, it is proposed to use air bubbles to rise from a pipe, which surrounds the pile-driving site in an approximately ring-like manner, for noise reduction during pile-driving operations. Due to the density inhomogeneity between the rising air bubbles and the surrounding seawater, as well as the compressibility of the air bubbles, the energy of the sound waves can be at least partially dissipated, so that a lower sound intensity prevails outside the bubble curtain. To achieve noise reduction in all directions, the pipe can be laid out so that it completely encircles the pile-driving site. If a reduction is only required in certain directions, the pipe can, of course, be laid out only in those directions, or the ring around the pile-driving site can be left open.

[0011] The compressed air exiting the pipeline is supplied by at least one compressor, which is usually mounted on the water's surface on a ship or jack-up barge. The compressed ambient air is then fed into the pipeline via a supply hose and exits through multiple boreholes drilled along the pipeline's length.

[0012] Since the pipe is constantly filled with air during operation of the device, buoyancy forces act upon it. However, for the noise barrier to function, it is essential that the pipe remains on the seabed. Otherwise, the noise emanating from the pile driving can pass unimpeded between the pipe and the seabed and thus propagate at full intensity.

[0013] According to the invention, it is proposed to insert a weight inside the pipeline. This increases the overall weight of the pipeline sufficiently to allow it to remain on the seabed without additional anchors or external weights. Since the weight is located inside the pipeline, its external shape remains unchanged, allowing it to continue to be easily deployed and / or removed without external weights hindering the process. While additional anchoring by divers is possible, it is generally unnecessary. At the very least, the number of anchors can be reduced or the spacing between them increased, as the pipeline's own weight keeps it in place on the seabed.

[0014] In some embodiments of the invention, the weighting element may contain a metal or an alloy. In other embodiments, the weighting element may contain or consist of a mineral material, such as concrete. The weighting element(s) may be incorporated directly into the pipe during production, for example, by extrusion. Weighting elements may also be glued, screwed, or riveted into the pipe at certain intervals. In one embodiment of the invention, several weighting elements may be connected to one another by a wire rope or chain, which prevents slippage along the longitudinal extent of the pipe. In another embodiment of the invention, at least one sufficiently dimensioned chain with a plurality of chain links may be used as the sole weighting element.

[0015] Such a weight can simply be inserted into the cable. Due to the flexibility of the chain links, the weight does not, or only minimally, impede the winding and unwinding of the cable.

[0016] In some embodiments of the invention, the conduit can have at least one longitudinal section comprising a hose with a wall, wherein the wall contains at least one layer of wire mesh. In some embodiments of the invention, several layers of wire mesh can be present in the wall. In some embodiments of the invention, the number of layers of wire mesh can be between 1 and 8, between 2 and 7, or between 3 and 5. The wire mesh in the wall of the hose increases its tensile strength, thus preventing mechanical damage or unacceptable changes in cross-section or length when the hose is unwound. Furthermore, the wire mesh can limit the elasticity of the hose, so that it retains its desired cross-section even under high overpressure. This allows the device to be operated with greater reliability and to be inserted and removed with particular safety.

[0017] In some embodiments of the invention, the wire mesh and / or the chain, or at least one weighting element, may contain or consist of stainless steel. For the purposes of this description, stainless steel is understood to mean an alloy steel that is corrosion-resistant or at least corrosion-inhibiting. For example, steels with material numbers 1.4401, 1.4571, or 1.4462 may be used. The use of these stainless steels extends the service life of the proposed device if seawater comes into contact with the weighting element and / or the wire mesh through the air outlet openings or damage to the wall.

[0018] According to the invention, the noise-shielding device further comprises at least one winding device with at least one drum onto which the cable can be wound. In some embodiments of the invention, the drum can have a drive, for example, an electric or hydraulic drive. The drum can be configured to accommodate more than approximately 900 m, more than approximately 1000 m, or more than approximately 1100 m of the cable. With the proposed winding device, the cable can be unwound from a work vessel and laid on the seabed, similar to an anchor chain. Provided the vessel travels in a circle around the pile-driving site, all directions of sound propagation can be covered.

[0019] To retrieve the cable after completion of the work, in some embodiments of the invention it may be sufficient to wind the cable onto the drum while the ship is essentially drifting without propulsion or with minimal engine power. This allows the ship to be guided by the cable as if by an anchor chain, following the cable's path backwards as the cable is wound onto the drum. Particularly with this method of installing and removing the cable, a cable with increased tensile strength, such as the proposed embodiment with at least one wire mesh in its wall, proves advantageous. The ballast body can also serve to absorb tensile forces if it contains or consists of a chain or wire rope.

[0020] In some embodiments of the invention, several conduits can be deployed simultaneously, each encircling the noise source in a ring-like fashion. This creates several bubble curtains arranged approximately concentrically. Since a single bubble curtain from a single conduit reduces the noise by approximately 12 dB to approximately 20 dB, a correspondingly greater reduction can be achieved by using multiple bubble curtains. If several conduits are deployed simultaneously, this improved noise protection can be installed in a single passage of the ship around the pile-driving site. In some embodiments of the invention, the number of conduits deployed simultaneously can be approximately 2 to approximately 6.

[0021] In some embodiments of the invention, several cables can be deployed simultaneously by unwinding each cable from an associated winding device, which unwinds the cables at different speeds. If the winding devices each have drums of the same diameter, the rotational speed can be selected differently. According to the invention, it has been found that the cables are laid at intervals on the seabed. For example, in some embodiments of the invention, the speed can be selected such that the cables are arranged substantially concentrically, with the outer cable laid with a radius that is approximately 10 m to approximately 30 m larger than the radius of the inner cable.

[0022] According to the invention, the drum of the winding device has an internal air supply, so that the cable can be pressurized with compressed air during unwinding and / or retraction. This provides additional mechanical stabilization to the cable, preventing it from experiencing excessively small bending radii that could damage it. Furthermore, it prevents the ingress of seawater and sand, which could clog individual bores in the cable wall.

[0023] The invention will now be explained in more detail with reference to figures, without limiting the general concept of the invention. This will show: Figure 1 shows an embodiment of a cable proposed according to the invention. Figure 2 shows a connecting element for two cable sections according to an embodiment of the invention. Figure 3 shows a winding device according to an embodiment of the invention. Figure 4 shows the cross-section through a cable. Figure 5 illustrates the operating principle of the proposed soundproofing device.

[0024] Figure 1 Figure 11 shows a hose 11 which can be used as a conduit 10 in a soundproofing device 1 according to the invention. The hose 11 can form at least a longitudinal section of the conduit 10. In other embodiments of the invention, the conduit 10 can be formed entirely by the proposed hose.

[0025] Hose 11 has a wall 111, which is determined by Figure 4This will be explained in more detail. The wall 111 encloses the clear width 116 of the hose 11. The wall 111 can be made of rubber or a polymer. For example, the wall 111 can contain or consist of polyvinyl chloride or EPDM. To improve the tensile strength and compressive strength of the hose 11, the wall 111 can contain at least one wire mesh 112, 113, or 114. Figure 4 Figure 1 shows an embodiment with three approximately concentrically arranged layers of wire mesh. These can be inserted into the wall 111 during extrusion or vulcanization of the tube 12. In other embodiments of the invention, the number of wire mesh layers 112, 113, and 114 can be larger or smaller, ranging from approximately 1 to approximately 7. In some embodiments of the invention, one wire mesh layer can also be omitted.

[0026] The wall 111 has a plurality of bores 105, one of which has a cross-section of Figure 4 The bores 105 can have a diameter of approximately 0.5 to approximately 5 mm. The bores 105 can be arranged at intervals of approximately 100 cm to approximately 10 cm in the wall 111.

[0027] On the inner side 115 of the wall 111, at least one weight rests, which compensates for the buoyancy of the tube 111 to such an extent that it remains on the seabed, even when the remaining clear opening 116 of the tube 11 is filled with compressed air. As shown by Figure 1As explained, in the illustrated embodiment, a chain with a plurality of chain links 102 is used as the weighting element 101. In such an embodiment, the hose 11 or the line 10 remains flexible, so that it can be easily wound and unwound, and thus laid on and removed from the seabed in a particularly simple manner. Even if the chain 101 fills a large part of the clear opening 116, the compressed air can still flow through the line 10 between the links 102. Furthermore, the chain 101, as well as the wire mesh 112, 113, and 114, can further increase the tensile strength of the line 11, thus preventing damage during the insertion and removal of the line 10.

[0028] The wire mesh 112, 113 and 114, as well as the chain 101 or another weighting element, can be made of corrosion-resistant or corrosion-resistant steel in some embodiments of the invention. This extends the service life of the line 10 if seawater enters the line during operation of the device through defects or through the bores 105.

[0029] Figure 2Figure 1 shows a connecting element 40 with which different longitudinal sections of a hose 11 can be joined to form a single line 10. The connecting element 40 has a sleeve 41. The sleeve 41 consists of a cylindrical base body on the outside of which a plurality of ribs 45 are arranged. The outer diameter of the cylindrical base body 41 corresponds approximately to the inner diameter 116 of the hose 11. In this way, the hose 11 can accommodate the cylindrical base body 41, with the ribs 45 lying against the inner wall 115.

[0030] After two hoses have been pushed onto the base body 41 from both sides, the joint can be inserted into a clamp 43 designed as a half-shell. The clamp 43 is then closed with a screw connection 47 via bores 44.

[0031] Optionally, the clamp 43 can have recesses or ribs 46 which are shaped or arranged complementarily to the ribs 45. In this way, a positive-locking connection of the hose 11 with the cylindrical base body 41 is achieved, so that high tensile forces can be transmitted in the direction of the longitudinal extension of the hose 11 without the hose 11 slipping out of the connecting element 40.

[0032] Figure 5 shows an application example of the soundproofing method or soundproofing device proposed according to the invention. Figure 5 Figure 3 shows the tower of a wind turbine 3, which is anchored to the seabed 2 by means of a tripod 30. The water depth at the installation site of the wind turbine 3 can be, for example, approximately 10 m to approximately 45 m or approximately 25 m to approximately 40 m.

[0033] The tripod 30 has mounting sleeves 31 at its base. The mounting sleeves 31 are designed to receive a driven pile 32. Provided that the tripod 30 is securely connected to the driven piles 32 and the driven piles 33 are securely anchored in the seabed 2, the wind turbine 3 stands reliably on the seabed 2. For this purpose, the driven piles 32 can have a diameter of approximately 2 m to approximately 5 m and a length of approximately 20 m to approximately 40 m.

[0034] The piles 32 are driven in with a pile driver (not shown), generating high-intensity sound emissions 21 which propagate as structure-borne sound in the seawater.

[0035] To reduce the impact of the sound emission 21 on marine fauna, the invention proposes to lay a conduit 10 in a ring shape around the pile driving point or around the entire tripod 30 with all pile driving points. For this purpose, the conduit 10 is unwound according to the invention from a winding device 15, which is mounted on a ship 11 and is guided by the Figure 3 This will be described in more detail. After the ship 11 has circled the construction site once and unrolled the pipeline 10, it rests on the seabed 2 due to its own weight. To reduce the ingress of seawater into the clear opening 116 of the pipeline 10 and / or to mechanically stabilize the pipeline 10, the pipeline 10 can be pressurized with compressed air from a compressor 18 during deployment. Due to the ballast inside the pipeline 10, it nevertheless sinks to the seabed under its own weight and remains there.

[0036] Before the pile driving begins, the pipeline 10 is pressurized with compressed air by at least one compressor 18 and a pipeline 181. The compressed air 180 leaves the pipeline 10 through the openings 105 and rises to the sea surface in the form of bubbles. The high-intensity sound emission 21 is attenuated as it passes through this bubble curtain 180, so that a lower sound intensity 22 is perceptible outside the area bounded by the pipeline 10.

[0037] Once the work is completed, the cable 10 can be retrieved and brought back on board the ship 11 using the winding device 15, and is then available for the next use. To retrieve the cable 10, the ship 11 can drift without propulsion or with minimal engine power while the cable 10 is being wound in using the winding device 15. This ensures that the ship 11 follows the path of the cable 10, similar to when retrieving an anchor chain, thus preventing any kinking of the cable 10 or wrapping of the cable 10 around the tripod 30.

[0038] Based on Figure 3 The function of the winding device 15 is described. The winding device 15 has a frame 151. The frame 151 can have the external dimensions of a standard container, for example, the dimensions of a shipping container according to ISO 668. In this way, the winding device 15 can be transported and stored in a space-saving manner.

[0039] Provided that the frame 151 has the standard dimensions of a freight container, it can also have the connecting elements 153 of such a container, so that several winding devices 15 can be stacked on top of each other like containers, or mixed stacks of winding devices 15 and containers can be formed. This allows for a space-saving and cost-effective transport option on the ship 11.

[0040] A drum 152 is rotatably mounted in frame 151. The drum 152 can be designed to hold more than 500 m, more than 900 m, more than 1000 m, or more than 1100 m of hose 11. Since the hose 11 is made of flexible rubber or plastic and has a smooth outer surface due to the internally arranged weights, the hose 11 can be stored on the drum 151 in a particularly space-saving manner.

[0041] To deploy the hose 11, the drum 152 can be set in rotation by a hydraulic drive (not shown) so that the hose 11 is unwound while the ship 19 circles the area designated for the noise abatement measures. Provided the drive of the drum 152 is sufficiently powerful, the ship 19 can be pulled backwards by the hose 11 to retrieve it, with the hose 11 winding onto the drum 152.

[0042] Furthermore, in Figure 3 A compressed air connection 154 is visible. The line of a compressor 18 can be connected to connection 154, which supplies compressed air to line 11. Due to the compressed air connection of the hose 11 being located inside the drum, the hose 11 can be pressurized with compressed air even while it is being unwound.

[0043] Naturally, the invention is not limited to the embodiments shown in the figures. The foregoing description should therefore be regarded not as limiting, but as explanatory.

Claims

1. Sound insulation device (1) for underwater pile driving work, having at least one line (10), which can be fixed on the seabed (2) and has a plurality of bores (105), and at least one winding device (15) with a drum (152), on which the line (10) can be wound, characterized in that there is a compressed-air connection for the line (10) being arranged inside the drum (152) of the winding device (15), and a ballast body inserted in the line (10).

2. Sound insulation device according to claim 1, characterized in that the compressed-air connection located inside the drum (152) is configured to apply compressed air to the line during unwinding and / or during pulling-in.

3. Sound insulation device according to claim 1 or 2, characterized in that the pressure of the compressed air can be selected in such a way that the penetration of seawater into the line (10) is prevented during unwinding.

4. Sound insulation device according to any of claims 1 to 3, further comprising a hydraulic drive, by means of which the drum (152) can be driven.

5. Sound insulation device according to any of claims 1 to 4, characterized in that more than 500 m or more than 900 m, more than 1000 m or more than 1100 m of the line (10) can be wound on the drum (152).

6. Ship (19) or jack-up barge with at least one sound insulation device according to any of claims 1 to 5.

7. Method for reducing the transmission of sound in a liquid, comprising the following steps: - laying at least one line (10) on the seabed (2), which annularly encloses the sound source and is provided with bores (105), - introducing compressed air (180) into the at least one line (10) so that it exits through the bores (105), characterized in that - the line is unwound from the drum (152) of a winding device (15), which has a compressed-air connection for the line (10) that is arranged inside the drum (152) of the winding device (15), and by - a ballast body inserted in the line (10).

8. Method according to claim 7, characterized in that compressed air is applied to the line (10) during unwinding and / or during pulling-in via the compressed-air connection located inside the drum (152).

9. Method according to claim 7 or 8, characterized in that more than 900 m, more than 1000 m, or more than 1100 m of the line (10) are unwound from the drum (152).

10. Method according to any of claims 7 to 9, characterized in that the pressure of the compressed air is selected in such a way that the penetration of seawater into the line (10) is avoided during unwinding.

11. Method according to any of claims 7 to 10, characterized in that at least two lines (10) are laid out simultaneously, each line being unwound from an associated drum (152) and the two drum (152) having a different rotational speed.

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