JP7245196B2 - Underwater noise suppression composition, manufacturing method thereof, underwater noise suppression structure and underwater noise suppression method using the same - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an underwater noise suppressing composition for suppressing underwater noise, a manufacturing method thereof, an underwater noise suppressing structure using the same, and an underwater noise suppressing method.

The driving of steel pipe piles for main construction (pile type structures, etc.) such as embankments and revetments is the main cause of underwater noise and vibration. be. In particular, when constructing a bottom-mounted offshore wind power foundation with large-diameter steel pipe piles in coastal areas, it is assumed that Japan's offshore wind power generation will be installed at a water depth of 20 to 30 m, and the noise generated will affect the surrounding water environment. believed to have a serious impact on

As a method for suppressing underwater noise during steel pipe pile driving, countermeasures such as air bubble curtains (Patent Document 6), pile sleeves (Non-Patent Document 1), underwater noise reduction devices and deployment systems (Patent Document 1), etc. have already been proposed. It has been implemented.

The present inventors previously disclosed in Japanese Patent Application No. 2020-014408 that a structure for suppressing underwater noise caused by pile driving, etc., and a submerged embankment installation type in which stones or concrete blocks are stacked, which has a function as a fish reef or algae reef after construction. proposed an underwater noise suppression structure.

Japanese Patent Publication No. 2017-504844 JP-A-2001-232622 JP 2012-162418 A Patent No. 2746333 JP-A-3-112876 Japanese Utility Model Laid-Open No. 01-119431

Michael A.Bellmann "Overview of existing Noise Mitigation Systems for reducing Pile-Driving Noise" Inter-noise 2014 MELBOURNE AUSTRALIA 16-19 NOVEMBER "Expanded polystyrene beads" Toyo Chemicals Co., Ltd. http://www.toyochem.co.jp/products-07-eps.html

The underwater noise suppression structure is installed underwater so as to suppress the diffusion of underwater noise to surrounding water areas by distance attenuation of underwater sound pressure and reflection/absorption/transmission of underwater sound. The material itself does not attempt to reduce or suppress underwater noise by sound absorption or sound reduction. General concrete structures such as wave-dissipating blocks and covering blocks are highly versatile, but in terms of suppressing underwater noise, the sound pressure transmission loss of the material itself is lower than that of air bubbles, iron, or the like. However, increasing the air content in the concrete can increase the sound pressure transmission loss of the concrete structure in water.

The air content (fine air bubbles) of ordinary concrete used for general concrete structures is stipulated to be 4.5% (tolerance ±1.5, JIS A 5308) at the time of unloading. It has been clarified that the amount of air in the normal concrete after it is reduced by about 1% from the time when it is fresh. In addition, as for special concrete that contains air to reduce weight, lightweight foamed concrete (Patent Document 2), lightweight foamed concrete mixed paste (Patent Documents 3 and 4) in which air bubbles are mixed in foaming aqueous solution, expanded styrene grains There is ultralight concrete using (Patent Document 5).

The above-mentioned ^special concrete has a specific gravity of about 0.2 to 1.6t/m ³ , an air content of 10 to 90%, and a compressive strength of 0.3 to 24N/mm ³ . and lightweight. On the other hand, stability against sliding and overturning due to waves is especially important for concrete structures installed in the sea.

Although the underwater noise suppressing concrete structure described above needs to have a stable underwater mass, the special concrete described above is not suitable as a constituent material for such an underwater noise suppressing concrete structure because of its light weight. In addition, in order to suppress underwater noise even in an installation environment that is constantly immersed in seawater, it is desired that a constant amount of air can be maintained at least during the period of construction that generates underwater noise.

In view of the problems of the prior art as described above, the present invention provides an underwater noise suppression component that effectively suppresses underwater noise and has a stable mass underwater, a method for manufacturing the same, and an underwater noise suppression using the same. It is an object of the present invention to provide a structure and underwater noise suppression method.

The present inventors have conceived that when an underwater noise suppression structure to be installed underwater is made of concrete, it is possible to suppress transmission of underwater noise by increasing the amount of air in the concrete, and have arrived at the present invention. be.

That is, the underwater noise suppressing structure for achieving the above object is a concrete structure for suppressing transmission of underwater noise, and contains 1 to 40 vol % of suppressing air.

According to this underwater noise suppression structure, in addition to the amount of air specified by JIS etc. for workability and durability, 1 to 40 vol% of air is included in the concrete structure to suppress underwater noise. As a result, the underwater sound pressure transmission loss can be enhanced, and the concrete structure absorbs or attenuates underwater noise and efficiently suppresses its transmission, thereby reducing and suppressing underwater noise. The underwater noise suppression composition can be used to construct an underwater noise suppression structure that suppresses the diffusion of underwater noise.

Preferably, the underwater noise suppression composition includes aggregate having a high specific gravity so as to at least compensate for the reduction in weight per unit volume due to inclusion of the suppression air. As a result, a stable mass in water can be secured even if suppression air is included in the concrete, and stability in water can be realized. Further, by adjusting the amount of aggregate having a large specific gravity, the weight per unit volume of the underwater noise suppression structure and the total weight can be adjusted.

It is preferable to use one or two or all of blast furnace slag, steel slag and non-ferrous metal slag as the aggregate. It should be noted that such aggregates can be used not only to compensate for the weight loss per unit volume due to the inclusion of suppressing air, but also to increase the weight of the underwater noise suppression construct.

Also, it is preferable that the suppressing air exists in the concrete structure as a large number of air bubbles.

Further, it is preferable to improve airtightness by applying a surface waterproofing agent to the concrete structure. As a result, surface water can be prevented from entering the inside of the concrete structure even if it is installed in water, suppressing air/bubbles in the concrete structure can be maintained, and deterioration of the underwater noise suppressing effect can be prevented.

A method for manufacturing an underwater noise suppression composition for achieving the above object is a method for manufacturing a concrete composition for suppressing transmission of underwater noise, comprising mixing cement, water and aggregate, 1 to 40 vol % of the forming material is mixed.

According to this method of manufacturing an underwater noise suppression structure, by manufacturing a concrete structure by mixing 1 to 40 vol% of a bubble-forming material, the amount of air specified by JIS, etc. for workability and durability can be reduced. In addition to suppressing underwater noise, it is possible to further increase the suppression air in the concrete structure, thereby increasing the sound pressure transmission loss in water, and the concrete structure absorbs underwater noise. Since it attenuates sound and effectively suppresses its transmission, underwater noise can be reduced and suppressed.

In the above-described method for manufacturing an underwater noise suppression structure, it is preferable to use a material having a large specific gravity as the aggregate so as to at least compensate for the reduction in weight per unit volume of the concrete structure due to the mixing of the air-bubble-forming material. As a result, even if the concrete structure contains air bubbles, a stable mass in water can be ensured, and stability in water can be realized.

The aggregate is preferably one or two or all of blast furnace slag, steel slag and non-ferrous metal slag. It should be noted that such aggregates can be used not only to compensate for the loss of weight per unit volume due to inclusion of air, but also to further increase the weight of the underwater noise suppression component.

Further, it is preferable to improve airtightness by performing underwater curing or wet curing after placing the concrete structure and/or applying a surface waterproofing agent to the concrete structure. As a result, it is possible to prevent surface water from entering the inside of the concrete structure even if it is installed in water, to maintain air bubbles in the concrete structure, and to prevent deterioration of the effect of suppressing underwater noise.

Further, it is preferable that expanded polystyrene beads are used as the cell-forming material, and that the particle size of the expanded polystyrene beads is 1 mm or more and equal to or less than the maximum size of the coarse aggregate among the aggregates.

An underwater noise suppression structure for achieving the above object includes the underwater noise suppression component described above or an underwater noise suppression component manufactured by the method for manufacturing an underwater noise suppression component described above, and generates underwater noise. It is installed in the direction to suppress the diffusion of the underwater noise around the point.

According to this underwater noise suppression structure, the underwater noise suppression structure is included, and is installed in a direction to suppress the diffusion of the underwater noise around the point where the underwater noise is generated, thereby absorbing or attenuating the incident underwater noise. , the permeation thereof is suppressed, so that the diffusion of underwater noise can be efficiently suppressed. As a result, it is possible to prevent underwater noise from adversely affecting aquatic organisms in the water area surrounding the point where the underwater noise is generated.

In the underwater noise suppression structure, it is preferable that the underwater noise suppression component is arranged at least on the incident surface of the underwater noise. By arranging the underwater noise suppression component on the incident surface of the underwater noise of the underwater noise suppression structure, it is possible to suppress the penetration of the underwater noise that propagates through the water and is incident.

It is preferable that the underwater noise suppression structure has a curved shape or a multifaceted shape with different inclination directions on the incident surface. Underwater noise can be efficiently reflected by obtaining a sound reflection effect on a curved or multifaceted incident surface with different inclination directions, which is effective in suppressing transmission of underwater noise.

Further, the underwater noise suppressing component may be arranged on the bottom surface in contact with the water bottom surface, so that further propagation of underwater noise propagating in the underground part of the water bottom can be suppressed.

In addition, the underwater noise suppression structure may be entirely composed of the underwater noise suppression component, and can suppress the transmission of underwater noise that propagates through the water and is incident, and propagates in the underground part of the water bottom. Further propagation of underwater noise can be suppressed.

Further, by arranging the underwater noise suppressing component on the water bottom in the vicinity of the point where the underwater noise is generated, it is possible to suppress the underwater noise propagating in the underground part of the water bottom.

Also, the underwater noise suppression structure may be arranged on a foundation installed on the bottom of the water.

Also, the underwater noise suppression structure may be suspended underwater. For example, by suspending an underwater noise suppressing component underwater in the vicinity of an underwater noise generation point, it is possible to suppress the diffusion of underwater noise propagating through the water.

An underwater noise suppression method for achieving the above object is a structure including the underwater noise suppression component described above or an underwater noise suppression component manufactured by the method for manufacturing an underwater noise suppression component described above. is installed in a direction that suppresses the diffusion of the underwater noise in the vicinity of the generation point of the underwater noise.

According to this underwater noise suppression method, a structure including an underwater noise suppression component is installed in a direction in which diffusion of underwater noise is desired to be suppressed around a point where underwater noise is generated, thereby absorbing or reducing incident underwater noise. and suppresses its transmission, so that the diffusion of underwater noise can be efficiently suppressed.

According to the present invention, it is possible to provide an underwater noise suppression structure that effectively suppresses underwater noise and has a stable mass underwater, a method for manufacturing the same, an underwater noise suppression structure using the same, and an underwater noise suppression method. can.

4 is a graph showing the specific acoustic impedance of various substances and the transmission loss of sound pressure propagating in water. 4 is a flow chart showing steps from manufacturing to installation of an underwater noise suppression structure according to the present embodiment; 1 is a cross-sectional view of a main part showing an example of an underwater noise suppression structure according to this embodiment; FIG. FIG. 4 is a cross-sectional view of a main part showing another example of the underwater noise suppression structure according to the present embodiment; FIG. 4 is a cross-sectional view of a main part showing another example of the underwater noise suppression structure according to the present embodiment; FIG. 5 is a cross-sectional view of a main part showing still another example of the underwater noise suppression structure according to this embodiment; FIG. 5 is a cross-sectional view of a main part showing still another example of the underwater noise suppression structure according to this embodiment; 3A and 3B are a cross-sectional view (a) and a top view (b) showing still another example of the underwater noise suppression structure according to the present embodiment; FIG. FIG. 11 is a side view of a main part showing another underwater noise suppression structure according to this embodiment; FIG. 10 is a side view of a main part showing an example of a connecting portion between the underwater noise suppression component of FIG. 9 and a foundation; FIG. 10 is a side view (a) of a main part showing a modification of the underwater noise suppression structure of FIG. 9 and a side view (b) of a main part showing another modification; FIG. 10 is a side view of a main part showing a configuration for forming an air bubble curtain in the noise suppression structure shown in FIG. 9; 3A to 3C are side views (a) to (c) of essential parts showing an underwater noise suppression structure in which the underwater noise suppression component according to the present embodiment is suspended underwater. It is a figure which shows the mix|blending of the concrete in this experiment example. It is a figure which shows the content rate (volume ratio) of an air bubble bead in this experiment example, and the unit volume weight of concrete. 4 is an appearance photograph of foam beads used in this experimental example. 4A to 4D are external photographs (a) to (d) of concrete blocks having foam bead contents (volume ratio) of 0, 1, 5, and 10% produced in this experimental example. It is a side view which shows roughly the experimental apparatus used by this experimental example. It is a graph which shows the underwater noise reduction effect confirmation result in this experiment example. It is a figure which shows the unit volume weight and mixing ratio of each slag-type aggregate. FIG. 21 is a diagram showing the unit volume weight of concrete when each slag-based aggregate of FIG. 20 is used.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a graph showing the characteristic acoustic impedance of various materials and the transmission loss of sound pressure propagating through water.

<Underwater noise suppression component>
The underwater noise suppression structure according to the present embodiment is a structure made of concrete, and by increasing the air volume in the concrete structure and taking measures to maintain the air volume, the transmission of underwater noise is suppressed and the suppression effect is maintained. Also, the mass is secured for stability in water.

Regarding the transmission loss of sound pressure propagating through water, such as pile driving sound, as shown in Fig. 1, the impedance loss that occurs when sound is incident on and transmitted through media (air, iron, etc.) with different specific acoustic impedances. Matching results in higher absorption. For example, sound insulators containing air bubbles and air, which have significantly different inherent densities and sound velocities than water, greatly affect the suppression of underwater noise. In general, the acoustic impedance of general concrete structures such as wave-dissipating blocks and covering blocks is 9.76-11.8×10 ⁶ kg/m ² s, and that of air (429 kg/m ² s) and iron (479× 10 ⁶ kg/m ² s), the impedance difference with water (1.54×10 ⁶ kg/m ² s) is small, and the sound pressure transmission loss of the material itself is small at about 3.26 to 3.89 dB.

That is, in general concrete structures, the sound pressure transmission loss of the material itself is low compared to air bubbles, iron, etc., in order to suppress underwater noise, whereas the underwater noise suppression structure according to this embodiment is made of concrete, and the concrete contains 1 to 40 vol% of suppressing air in addition to the normal contained air, so that the underwater sound pressure transmission loss of the underwater noise suppressing structure can be increased.

Specifically, in the concrete construction process, 1 to 40 vol% of air bubbles are contained in the concrete as suppression air, and by using aggregates with a heavy specific gravity, underwater noise suppression that secures mass underwater is achieved. of concrete structures (underwater noise suppression structures).

In addition, the airtightness of the concrete structure is improved by performing underwater and wet curing after casting into the formwork, and by applying a surface waterproofing agent after removing the frame, to prevent surface water from entering the concrete structure. , the air bubbles in the concrete composition can be maintained.

In addition, in order to contain air bubbles in the concrete, by using foamed polystyrene beads (hereinafter referred to as "air bubble beads"), which is a kind of fine air bubble forming material, air bubbles are suppressed in the concrete at 1 to 40 vol. %, and the content of suppression air can be easily adjusted. About 98% of the granules of foamed beads are air, the surface is made of styrene resin that does not allow water to pass through, and the interior is also composed of fine closed cells, so there is almost no water absorption (non-patented). Reference 2).

When the foam beads are used in water, the water pressure applied to the foam beads increases as the depth of water increases, and the volume of air contained decreases. Due to the strong organization and structure of concrete, the foam beads inside the concrete are not easily affected by water pressure, and a stable amount of air can be maintained even when concrete structures are installed in deep water.

The bubble content also depends on the stable required weight of the structure to be built, but in order to ensure underwater noise reduction performance, it should be at least 1% by volume compared to one without bubble beads. It is effective if there is content. Moreover, in order to prevent material separation of the foam beads contained in the concrete, it is desirable to suppress the content of the foam beads to 40% or less.

Considering workability and pumpability during construction, the size of the foam beads should be 1 mm or more, and should be less than the maximum size of the coarse aggregate. If the foam beads are 1 mm or more, they are at least as large as the fine aggregate, so they are easily mixed in the concrete.

Iron and steel slag and non-ferrous metal slag (ferronickel slag, copper slag) are used as the aggregate having a large specific gravity to increase the weight per unit volume (hereinafter referred to as unit volume weight) of the underwater noise suppression component. As a result, the stability of the underwater noise suppression structure composed of the underwater noise suppression component against sliding or overturning due to fluid force can be ensured. The use of such aggregate not only compensates for the reduction in unit volume weight of the underwater noise suppression composition due to inclusion of 1 to 40 vol % of air bubbles, but also makes it possible to further increase the unit volume weight of the underwater noise suppression composition.

According to the underwater noise suppressing structure of the present embodiment, the concrete structure contains 1 to 40 vol% of air bubbles as suppressing air, thereby increasing the sound pressure transmission loss in water. is absorbed and its transmission is efficiently suppressed, so that underwater noise can be suppressed. The underwater noise suppression composition can be used to construct an underwater noise suppression structure that suppresses the diffusion of underwater noise.

<Manufacturing process of underwater noise suppression structure>
Manufacturing steps S01 to S09 of the underwater noise suppression structure according to this embodiment will be described with reference to the flow chart of FIG.

As preparations before construction, a concrete mix is selected (S01). That is, considering the installation location, installation form, etc. of the underwater noise suppression structure, stable mass, strength, installation part (number) setting, aggregate mixing design, and bubble content mixing setting are performed. For this reason, samples for test pieces are prepared at a ready-mixed concrete factory, etc., and property tests (compressive strength, workability, pumpability, etc.) are performed, and if necessary, concrete adhesives, thickeners, etc. are added and the water-cement ratio is adjusted. adjust. In addition, blast furnace slag, iron and steel slag, and non-ferrous metal slag (ferronickel slag, copper slag) having a high specific gravity are used as part of the aggregate to increase the unit volume weight.

Next, in a ready-mixed concrete factory, cement, water and aggregate are kneaded according to the above-mentioned selected composition (S02), and this fresh concrete is loaded on a concrete agitator vehicle and transported (S03).

A set amount of foam beads in the range of 1 to 40 vol % is added as suppression air to the concrete agitator vehicle loaded with the fresh concrete (S04). When foam beads are mixed in advance at a ready-mixed concrete factory, they are stirred again with an agitator wheel (S05), and then cast into a mold (S06).

Next, the concrete after being placed is cured in water (S07). Depending on the construction period and conditions, it may be sealed and wet. As a result, the decrease in the airtightness of the concrete is suppressed and the air volume is maintained. In other words, it is important to prevent the amount of air in the concrete from decreasing in order to maintain the effect of suppressing underwater noise. In addition, when air curing, sealing curing, and underwater curing are performed, water permeation from the concrete surface is the lowest in the underwater curing and the highest in the air curing.

Next, the concrete is removed from the frame, and a waterproofing agent is applied to the concrete surface (S08). This prevents direct penetration of water into the concrete. It also prevents the occurrence of fine cracks that are initially generated on the surface layer through which the waterproofing agent permeates. If the surface waterproofing agent is applied to the entire surface, the construction cost will increase.

As described above, an underwater noise suppression structure, which is a concrete structure, is produced and installed in water (S09) to construct an underwater noise suppression structure in water. The underwater noise suppression structure is manufactured in a columnar shape, a plate shape, a block shape, or the like in conformity with the shape of the underwater noise suppression structure or the shape of a part of the underwater noise suppression structure.

<Underwater noise suppression structure>
An underwater noise suppression structure according to this embodiment will be described with reference to FIGS. 3 to 8. FIG. FIG. 3 is a cross-sectional view showing an example of an underwater noise suppression structure according to this embodiment. FIG. 4 is a cross-sectional view of a main part showing another example of the underwater noise suppression structure according to this embodiment. FIG. 5 is a cross-sectional view showing another example of the underwater noise suppression structure according to this embodiment. FIG. 6 is a cross-sectional view showing still another example of the underwater noise suppression structure according to this embodiment. FIG. 7 is a cross-sectional view showing still another example of the underwater noise suppression structure according to this embodiment. FIG. 8 is a cross-sectional view showing still another example of the underwater noise suppression structure according to this embodiment.

The underwater noise suppression structure 11 shown in FIG. It is placed in The underwater noise suppression structure 11 has a flat upper surface 12, an inclined surface 13 facing the underwater noise generation point 10, and an inclined surface 14 facing the surrounding water area, and has a trapezoidal submerged vertical cross section. It is configured. The inclined surface 13 side facing the underwater noise generation point 10 is partially composed of the underwater noise suppression component 16 . The underwater noise suppression component 16 may be configured, for example, in a plate shape, a block shape, or a tetra shape. good too.

Note that the portion of the underwater noise suppression structure 11 other than the underwater noise suppression component 16 may be made of general concrete, but is not limited to this, and may include rocks, stones, earth and sand, steelmaking slag, steelmaking slag, and viscosity. It may be composed of modified soil mixed with soil, cement-solidified soil mixed with cement and cohesive soil, or the like. Also, the inclined surfaces 13 and 14 may stand upright without being inclined. Also, the upper surface 12 may not be flat, and may be, for example, mountain-shaped or arc-shaped.

As shown in FIG. 3, the sound pressure due to underwater noise from the generation point 10 propagates in the direction of the arrow a and enters the underwater noise suppression structure 16 on the inclined surface 13, and part of it passes through the underwater noise suppression structure 16. , the sound pressure undergoes a transmission loss due to the underwater noise suppression structure 16, travels through the underwater noise suppression structure 11 in the arrow direction b indicated by the dashed line, and emerges from the inclined surface 14 on the opposite side, the sound pressure is Since it is attenuated, the diffusion of underwater noise to the surrounding water area side is suppressed. Part of the sound pressure incident on the underwater noise suppression structure 16 is separately reflected by the inclined surface 13 in the direction c, directed toward the generation point 10, and is not diffused toward the surrounding water area of the underwater noise.

Compared to FIG. 3, the underwater noise suppression structure 11A of FIG. 4 includes an underwater noise suppression structure 16 on the upper surface 12 side and the inclined surface 14 side in addition to the inclined surface 13 side. Similar to FIG. 3, the diffusion of underwater noise from the generation point 10 to the surrounding water area side is similarly suppressed.

Compared with FIG. 3, the underwater noise suppression structure 11B in FIG. 5 is entirely composed of an underwater noise suppression component 16, and other configurations are the same as in FIG. The sound pressure propagating inside the body 11B is further attenuated, and the diffusion of the underwater noise from the generation point 10 to the surrounding water area side is further suppressed. In addition, even if the sound pressure generated by pile driving propagates in the direction of arrow d in the underwater part G and is incident on the bottom surface 15 of the underwater noise suppression structure 11B in the direction e indicated by the broken line from the bottom of the water, the sound pressure is reduced. Therefore, the diffusion of underwater noise to the surrounding water area side is suppressed. The underwater noise suppression structure 11B can be constructed by, for example, stacking a large number of block-shaped underwater noise suppression components 16, but may have other shapes.

Compared to FIG. 3, the underwater noise suppression structure 11C shown in FIG. 6 includes an underwater noise suppression component 16 on the bottom surface 15 side in addition to the inclined surface 13 side. Therefore, the diffusion of underwater noise from the generation point 10 to the surrounding water area side is similarly suppressed. Further, a plate-like underwater noise suppressing component 17 is arranged at the pile foot protection portion 19 of the steel pipe pile 9 driven into the bottom of the water at the underwater noise generation point 10 . The underwater noise suppression component 17 of the pile foot protection portion 19 attenuates the sound pressure caused by the pile driving that advances into the underwater underground part G, and the sound pressure that propagates in the underwater underground part G in the direction of arrow d is reduced. Even if the sound is incident on the bottom surface 15 of the underwater noise suppression structure 11C in the direction e indicated by the dashed line from the surface, the sound pressure is further reduced, so that the diffusion of the underwater noise to the surrounding water area is further suppressed. 6, the underwater noise suppression structure 17 has a hole 17a slightly wider than the outer diameter of the pile 9 to be driven into a part of the plate-like shape, and the pile is inserted into the hole 17a. You may make it pour through 9.

Compared to FIG. 3, the underwater noise suppression structure 11D of FIG. 7 includes an underwater noise suppression component 16 on the upper surface 12 side in addition to the inclined surface 13 side, and other configurations are the same as in FIG. However, by forming an air bubble curtain BC on the upper surface 12 of the underwater noise suppression structure 11D, diffusion of underwater noise between the water surface and the upper surface 12 is suppressed. A means for forming the air bubble curtain BC is disclosed in Patent Document 6, for example. 4 to 6, the air bubble curtain BC may be similarly formed.

The underwater noise suppression structure 11E shown in FIGS. 8(a) and 8(b) has a plate-shaped underwater noise suppression structure 11E in the pile foot protection portion 19 of the steel pipe pile 9 driven to the bottom of the water at the underwater noise generation point 10, as in FIG. By arranging the suppressing structure 17, the sound pressure caused by pile driving into the underwater underground part G is attenuated. By covering the pile sleeve PS with an inner diameter larger than the outer diameter of the pile and arranging it so as to extend from the underwater noise suppression structure 17 to the vicinity of the water surface, the underwater noise caused by pile driving is suppressed from diffusing to the outside. be. 8B, the underwater noise suppression structure 17 has a hole 17b slightly wider than the outer diameter of the pile sleeve PS in a part of its plate-like shape. The pile 9 may be driven through the pile sleeve PS. Also, an air bubble curtain as shown in FIG. 7 may be formed around the steel pipe pile 9 instead of the pile sleeve PS.

Underwater sound pressure due to steel pipe pile driving propagates at different sound velocities in the water and in the ground below the bottom of the water, and propagates and diffuses in each medium. It is also effective as noise suppression.

Next, another underwater noise suppression structure according to this embodiment will be described with reference to FIGS. 9 to 12. FIG. FIG. 9 is a main part side view showing another underwater noise suppression structure according to this embodiment. FIG. 10 is a side view of a main portion showing an example of a connecting portion between the underwater noise suppressing component and the base portion of FIG. 9; FIG. 11 is a side view (a) of a main part showing a modification of the underwater noise suppression structure of FIG. 9 and a side view (b) of a main part showing another modification. FIG. 12 is a side view of a main portion showing a configuration for forming an air bubble curtain in the underwater noise suppression structure of FIG. 9;

The underwater noise suppression structure 21 of FIG. 9 includes an upright plate-like underwater noise suppression structure 22 and a base portion 23 installed on the bottom of the water to support the underwater noise suppression structure 22, and is an underwater soundproof wall type. It is constructed. The underwater noise suppressing component 22 is composed of a concrete component containing 1 to 40 vol% of suppressing air, and is connected to and supported by the foundation 23, so there is no need to increase the unit volume weight. No need to use aggregate. The base 23 is made of ordinary concrete. Sound pressure due to underwater noise from the noise generation point 10 propagates underwater and undergoes transmission loss at the plate-like underwater noise suppression component 22, the sound pressure is attenuated, and diffusion of the underwater noise to the surrounding water area side is suppressed. be.

In FIG. 9, the plate-like underwater noise suppressing structure 22 can be connected to the surface of the base portion 23 at its lower end surface 22a using a prick or a stud. A groove portion 23a may be provided in the groove portion 23a, and the underwater noise suppression component 22 may be fitted and connected to the groove portion 23a. As a result, the underwater noise suppression component 22 can be more reliably supported by the base portion 23 . In order to prevent slippage, grooves may be provided on the lower outer peripheral surface of the plate-like underwater noise suppressing component 22, and a rubber material may be arranged in the groove portion 23a at a position opposite to the grooves for connection.

An underwater noise suppression structure 21A shown in FIG. 11(a) has a plate-like underwater noise suppression component 25 supported by a base portion 23 installed on the bottom of the water, and partition walls 26 arranged at both ends thereof. The underwater noise suppressing structure 25 comprises an upright wall-like portion 25a and a bottom portion 25b wider than the wall-like portion 25a and connected to the base portion 23, and is made of a concrete structure containing 1 to 40 vol% of suppressing air. It is structured and does not use aggregate with a large specific gravity. Even if the wall-like portion 25a is formed thick in order to increase the sound pressure transmission loss in water, the partition walls 26 on both sides can stably support the underwater noise suppression component 25. FIG. The bulkhead 26 may be constructed from conventional concrete, but may also be constructed from an underwater noise dampening composition using aggregate of high specific gravity. In addition, at the time of selection of composition (S01), the composition is determined so as to have strength that can withstand ocean currents and tide level fluctuations at the installation location.

The underwater noise suppression structure 21B of FIG. 11(b) has the configuration of FIG. is almost identical to

In the example of FIG. 12, the underwater noise is diffused between the water surface and the upper end surface 22b by forming an air bubble curtain BC on the upper end surface 22b of the underwater noise suppression component 22 of the underwater noise suppression structure 21 of FIG. It is designed to suppress. It should be noted that the air bubble curtain BC may be similarly formed in FIGS. 11(a) and 11(b).

In FIGS. 9 to 12, the underwater noise suppression components 22 and 25 do not have to use an aggregate having a large specific gravity, but may be used to increase the weight per unit volume if necessary.

FIGS. 13(a) to 13(c) are main part side views showing an underwater noise suppression structure in which the underwater noise suppression structure according to the present embodiment is suspended underwater. The example of FIG. 13(a) includes an underwater noise suppressing structure 28 consisting of a plurality of columnar concrete structures 28a with a circular side cross section containing 1 to 40% suppression air, and a buoy portion 29 that generates buoyancy. , and suspended underwater. The underwater noise suppressing structure 28 comprises a plurality of columnar concrete structures 28a containing 1 to 40% of suppressing air, which are arranged so as to extend in the horizontal direction and connected to each other by known plate-like or rope-like connecting means. is constructed like a wall and suspended in the water by the buoyancy of the buoy part 29 . The underwater noise suppressing structure 30 has the underwater noise transmission suppressing effect of the underwater noise suppressing component 28 and the sound reflecting effect of the circular surface of each concrete component 28a, thereby suppressing the underwater noise generation point due to the steel pipe pile 9 being driven to the bottom of the water. Underwater noise propagating through the water from 10 can be suppressed by absorbing or attenuating it, and diffusion to the surrounding water area side can be suppressed. In addition, the underwater noise suppressing component 28 may be constructed in a plate shape as a whole and suspended underwater.

In the example of FIG. 13(b), as in FIG. 13(a), an underwater noise suppressing structure 28 made of a concrete structure 28a containing 1 to 40% of suppressing air and a plurality of columnar sound reflecting and absorbing structures 31a. and an underwater noise suppression structure 32 constructed from and suspended underwater. The outer shell of the sound reflecting/sound absorbing structure 31a is made of a metal material such as steel or stainless steel, a resin material such as vinyl chloride, polyethylene/polypropylene, or FRP. In addition, since the inside is a closed cavity, it absorbs, reflects, resonates, absorbs or reduces underwater noise, and suppresses its transmission. There is The sound reflecting/sound absorbing structure 31 has a plurality of columnar sound reflecting/sound absorbing structures 31a arranged so as to extend in the horizontal direction and connected to each other to form a wall as a whole. The restraint structure is suspended in the water by buoyancy. The underwater noise suppression structure 32 absorbs or attenuates the underwater noise propagating underwater from the generation point 10 caused by the installation of the steel pipe pile 9 to the bottom of the water by the underwater noise suppression component 28 and the sound reflecting/sound absorbing structure 31. It is possible to suppress the diffusion to the surrounding water area side. The side cross-sectional shape of the sound reflecting/sound absorbing structure 31a may be oval, semi-elliptical, semi-elliptical, polygonal or semi-polygonal such as a triangular or quadrangular shape with an inclined surface. have a sound reflection effect in

The example of FIG. 13(c) is similar to FIG. 13(a), an underwater noise suppressing hybrid structure composed of a concrete structure 28a containing 1 to 40% of suppressing air and the sound reflecting/sound absorbing structure 31a of FIG. 13(b). It is an underwater noise suppression structure 35 which is composed of a structure 33, a buoy portion 29, and a weight portion 34 having a weight located at the lowest end and suspended underwater. The underwater noise suppression hybrid structure 33 includes a plurality of columnar concrete structures 28a containing 1 to 40% of suppressing air and a plurality of columnar sound reflecting and absorbing structures 31a arranged alternately so as to extend in the horizontal direction. It is connected and configured like a wall to reduce and suppress underwater noise. The underwater noise suppression structure 35 is suspended in the water by the buoyancy of the buoy portion 27 and the sound reflecting/sound absorbing structure 31a, and absorbs or reduces the underwater noise propagating in the water from the generation point 10 caused by the installation of the steel pipe pile 9 to the bottom of the water. It can be suppressed by sound and spread to the surrounding water area side. The weight portion 34 is formed in a columnar shape from ordinary concrete or steel material, but is formed from a concrete structure 28a containing 1 to 40% of suppressing air, and aggregate having a large specific gravity is used to increase the unit volume weight. You may do so.

In FIGS. 13(a) to 13(c), the circular concrete structure 28a containing 1 to 40% of the suppression air has a side cross-sectional configuration such as an elliptical shape or a polygonal shape such as a triangle or quadrangle with an inclined surface. Alternatively, the shape may be semicircular, semi-elliptical, or semi-polygonal. It can effectively reflect noise. The concrete structure 28a and the underwater noise suppression structure 28 containing 1 to 40% of air for suppression may be made lightweight without using aggregate having a large specific gravity. The overall weight of the underwater noise suppression structures 30, 32, 35 may be adjusted.

Further, it is desirable to install the underwater noise suppression structures 30, 32, and 35 shown in FIGS. It is necessary to increase the dimension of the underwater noise suppression structure to be suspended underwater (the length in the vertical direction of the paper surface of FIGS. 13(a) to 13(c)) as the distance from the underwater noise generation point 10 is increased. This is because a large buoy or the like is required for In the underwater noise suppression structures 21, 21A, and 21B installed on the bottom of the water as shown in FIGS. On the other hand, by installing it at a closer position, it is possible to more efficiently suppress the diffusion of underwater noise propagating underwater to the surrounding water area. Also, it can be used in place of the air bubble curtain BC shown in FIGS.

Alternatively, the lower parts of the suspended underwater noise suppression structures 30, 32, 35 may be connected with anchors installed on the bottom of the water so that their installation positions do not move due to tidal currents. As in c), weight portions may be provided at the lower portions of the underwater noise suppression structures 30 and 32 .

3-7, 9-12 in underwater noise suppression structures 16, 22, 25, or 1-40% suppression air in FIGS. 13(a)-(c). It is preferred that the air bubbles in the concrete component 28a be distributed as evenly as possible. The underwater sound generated by driving the steel pipe pile 9 is planar in the vertical direction, has a long sound emission time, and propagates in the cross section of the entire water column, so many bubbles in the underwater noise suppression structure 16 are evenly distributed in the concrete. It is thought that this is effective in suppressing underwater noise transmission.

In addition, the examples in Figures 3 to 13 are based on the expected underwater noise source sound pressure, underwater organisms to be countermeasured, vertical distribution of water temperature and salinity, sea area conditions such as depth and bottom sediment, construction method and timing, etc. It is desirable to make a selection after considering the expected effect of countermeasures and cost-effectiveness.

<Experimental example>
Concrete blocks containing 0, 1, 5, and 10% by volume of foamed beads (about 2 mm in diameter) were prepared. In concrete blocks containing 1, 5, and 10% cellular beads, restraining air was incorporated by the cellular beads in addition to the amount of air contained in concrete blocks containing 0% cellular beads. The concrete mix is shown in FIG. 14 and the foam bead content and unit volume weight of the concrete is shown in FIG. Fig. 16 shows a photograph of the appearance of the foam beads used, and Figs. 17(a) to 17(d) show photographs of the concrete blocks with foam bead contents (volume ratios) of 0, 1, 5, and 10%. . This concrete block was placed in a small plastic water tank as shown in FIG. 18, and the underwater noise when the steel pipe was hit was measured with a sound pressure meter, and the results are shown in FIG. From the same figure, it was confirmed that the underwater noise suppression effect by installing concrete blocks was confirmed, and it was confirmed that the underwater noise suppression effect increased as the content of the foam beads increased.

The example of mixing concrete in FIG. 14 in the above experimental example is a general one, and the fine aggregate is sand, and the coarse aggregate is gravel or crushed stone, but as shown in FIG. The unit volume weight decreases according to Therefore, if slag-based aggregates (blast furnace slag, ferronickel slag, copper slag) with a large specific gravity are used as fine aggregate/coarse aggregate at a predetermined mixing ratio as shown in FIG. 20, the composition shown in FIG. As shown in the figure, the unit volume weight of concrete increases, and it is possible to compensate for the decrease in unit volume weight due to the fact that the concrete contains 1 to 40 vol% of suppressing air. It can be seen that the unit volume weight can be increased by

Although the embodiments for carrying out the present invention have been described above, the present invention is not limited to these, and various modifications are possible within the scope of the technical idea of the present invention. For example, in the present embodiment and experimental examples, expanded polystyrene beads (cell beads) were used as the bubble-forming material, but the present invention is not limited to this, and the same recycled material or bubble cushioning material as the expanded polystyrene beads may be used. It may also be a material having a honeycomb structure. In addition, air entrained air (entrenched air) by the surface active action of an AE agent, an AE attenuating agent, etc. may be used to form air bubbles in the concrete.

3 to 7 and 9 to 13, the underwater noise suppression structure is configured as a submerged bank type, an underwater soundproof wall type, or an underwater suspension type, but the present invention is not limited to this, and other structures may be used. It may be constructed in a structure, at least a portion of which structure is constructed from an underwater noise suppression composition according to the present invention.

According to the present invention, since transmission of underwater noise can be efficiently suppressed by the underwater noise suppression component, diffusion of underwater noise can be suppressed by the underwater noise suppression structure constructed underwater from the underwater noise suppression component. It is possible to prevent underwater noise from adversely affecting aquatic organisms.

9 Steel pipe pile 10 Underwater noise generation points 11, 11A to 11E Underwater noise suppression structures 13, 14 Inclined surface 15 Bottom surface 16, 17 Underwater noise suppression structure 19 Pile foot protection portion 21, 21A, 21B Underwater noise suppression structure 22 , 25 Underwater noise suppression structure 23 Foundation 28 Underwater noise suppression structure 28a Concrete structure 30, 32, 35 Underwater noise suppression structure G Submerged part

Claims (19)

A concrete structure for suppressing penetration of underwater noise,
An underwater noise suppression composition containing 1-40 vol% suppression air. 2. An underwater noise suppression composition as set forth in claim 1 including high specific gravity aggregate to at least compensate for the weight loss per unit volume due to inclusion of said suppression air. 3. An underwater noise suppression composition according to claim 2, wherein one or two or all of blast furnace slag, steel slag and non-ferrous metal slag are used as said aggregate. 4. An underwater noise suppression structure as claimed in any preceding claim, wherein the suppressing air exists within the concrete structure as a multiplicity of air bubbles. 5. An underwater noise suppression structure according to any one of claims 1 to 4, wherein airtightness is improved by applying a surface waterproofing agent to said concrete structure. A method of manufacturing a concrete structure for suppressing penetration of underwater noise, comprising:
A method of manufacturing an underwater noise suppression composition comprising mixing cement, water and aggregate, and further mixing 1-40 vol% of a cell-forming material. 7. The method of manufacturing an underwater noise suppression composition according to claim 6, wherein a material having a high specific gravity is used as said aggregate so as to at least compensate for the reduction in weight per unit volume of said concrete composition due to said air-forming material being mixed. 8. The method of manufacturing an underwater noise suppression composition according to claim 6 or 7, wherein one or two or all of blast furnace slag, steel slag and non-ferrous metal slag are used as the aggregate. 9. Underwater noise suppression according to any one of claims 6 to 8, wherein airtightness is improved by performing underwater curing or wet curing after placing the concrete structure and/or applying a surface waterproofing agent to the concrete structure. A method of manufacturing a construct. using foamed polystyrene beads as the cell-forming material,
10. The method for manufacturing an underwater noise suppression structure according to any one of claims 6 to 9, wherein the particle size of said expanded polystyrene beads is 1 mm or more and is equal to or less than the maximum size of coarse aggregates among said aggregates. An underwater noise suppression structure comprising the underwater noise suppression component according to any one of claims 1 to 5 or the underwater noise suppression component manufactured by the manufacturing method according to any one of claims 6 to 10. and an underwater noise suppressing structure installed in a direction to suppress the diffusion of the underwater noise in the vicinity of the point where the underwater noise is generated. 12. An underwater noise suppressing structure according to claim 11, wherein said underwater noise suppressing component is located at least on said incident surface of said underwater noise. 13. An underwater noise suppressing structure according to claim 12, wherein the underwater noise suppressing structure has a curved shape or a multifaceted shape with different inclination directions on the incident surface. 14. An underwater noise suppressing structure according to claim 12 or 13, wherein the underwater noise suppressing component is located on the bottom surface in contact with the water bottom surface. 12. An underwater noise suppression structure as defined in claim 11 constructed entirely from said underwater noise suppression composition. 16. An underwater noise suppressing structure according to any one of claims 11 to 15, wherein said underwater noise suppressing component is arranged on the bottom of the water near said underwater noise generating point. 14. An underwater noise suppression structure as claimed in any one of claims 11 to 13, wherein the underwater noise suppression component is arranged on a foundation installed on the bottom of the water. 14. An underwater noise suppressing structure according to any one of claims 11 to 13, wherein the underwater noise suppressing structure is suspended underwater. A structure including the underwater noise suppression composition according to any one of claims 1 to 5 or the underwater noise suppression composition manufactured by the manufacturing method according to any one of claims 6 to 10 is used to reduce underwater noise. An underwater noise suppression method for suppressing underwater noise by installing in a direction to suppress the diffusion of the underwater noise in the vicinity of the generation point.

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