JP7136411B1 - Scouring suppression method and scour suppression sheet - Google Patents

Abstract

A scouring suppression method and a scouring suppression sheet capable of effectively suppressing scouring of the submerged ground on which piles are driven while having a simple configuration are provided. A water-permeable scouring suppression sheet 1 is laid on the water bottom ground G, and piles 30 are made to penetrate the scouring suppression sheet 1 into a target placement range, and when the scouring suppression sheet 1 is driven into the water bottom ground G, washing is performed. The target placement range of the excavation suppression sheet 1 is set in a tense state. Alternatively, scouring suppression having a water-permeable sheet member 2 having water permeability and an elongation-restricting sheet member 3 integrated over the target driving range of the water-permeable sheet member 2 that is driven by penetrating the pile 30. The sheet 1 is laid on the water bottom ground G, and the piles 30 are driven into the water bottom ground G by penetrating the target driving range of the water permeable sheet member 2 and the elongation restraining sheet member 3 . [Selection drawing] Fig. 2

Description

TECHNICAL FIELD The present invention relates to a scouring suppression method and a scouring suppression sheet, and more particularly, a scouring suppression method and a scouring suppression that can effectively suppress scouring of the submerged ground on which piles are driven while having a simple configuration. Regarding the seat.

An offshore wind power generator has a structure in which an upper structure having a windmill is fixed to the top of piles driven into the seabed. When water currents due to waves and tides hit piles, downward currents are generated, and along with this, horseshoe-shaped eddies and trailing eddies that scour the water bottom sediment near the roots of piles are generated. As the scouring of the water bottom where the piles are driven progresses, the bearing capacity of the piles decreases, which causes the tilting of the piles. Conventionally, scouring of the waterbed ground is suppressed by laying stones around the piles after driving the piles into the waterbed ground. However, in this construction method, scouring progresses in the peripheral area of the pile after the pile is driven until the stone material is completely laid. In addition, it takes a lot of labor to lay stones around the piles, and the stones may damage the piles.

Therefore, a method has been proposed in which scouring of the water bottom can be suppressed from the time the pile is driven (see, for example, Patent Document 1). In the invention described in Patent Document 1, an auxiliary foundation structure having a cylindrical wall portion through which foundation piles of an offshore wind turbine can pass and a bottom portion extending outward from the lower end portion of the wall portion is provided on the water bottom. It is installed on the ground and driven with the foundation piles inserted through the auxiliary foundation structure. However, with this method, it is necessary to manufacture a heavy and long auxiliary foundation structure that extends from the bottom of the water to the surface of the water, requiring a great deal of cost and labor for transporting and installing the auxiliary foundation structure. In addition, since the downward flow generated by the water flow hitting the auxiliary foundation structure propagates to the outside of the auxiliary foundation structure, there is a risk that the water bottom sediment outside the auxiliary foundation structure will be scoured.

JP 2020-190152 A

SUMMARY OF THE INVENTION An object of the present invention is to provide a scouring suppression method and a scouring suppression sheet that can effectively suppress scouring of the submerged ground on which piles are driven while having a simple configuration.

In order to achieve the above object, the scouring suppression method of the present invention is a scouring suppression method for suppressing scouring of the waterbed ground in which piles are to be driven, wherein a water-permeable scouring suppression sheet is laid on the waterbed ground. Further, when the pile is driven through the target placement range of the scouring suppression sheet and driven into the seabed ground, the target placement range is set in a tense state.

In order to achieve the above object, another scouring suppression method of the present invention is a scouring suppression method for suppressing scouring of the submerged ground in which piles are driven, comprising a water-permeable sheet member having water permeability and the piles A scour-suppressing sheet having an elongation-suppressing sheet member that is superimposed and integrated in a target placement range of the water-permeable sheet member to be driven through is laid on the waterbed ground, and the pile is placed on the water-permeable sheet. It is characterized in that the member is driven into the water bottom ground by penetrating the target driving range and the elongation restraint sheet of the member.

In order to achieve the above object, the scouring suppression sheet of the present invention is a scouring suppression sheet that is laid on the waterbed ground on which piles are driven to suppress scouring of the waterbed ground, and has water permeability. It has a water-permeable sheet member , and is a partial region of the water-permeable sheet member when the pile penetrates the target driving range of the water-permeable sheet member and is driven into the underwater ground. It is characterized by having a tension maintaining structure that makes the target placement range more tensed than a peripheral region of the water-permeable sheet member around the target placement range .

In order to achieve the above object, another scouring-suppressing sheet of the present invention is a scouring-suppressing sheet that is laid on the waterbed ground on which piles are driven and suppresses scouring of the waterbed ground, and is water-permeable. and a partial region of the water-permeable sheet member is set in advance as a target driving range through which the pile is driven, and the target driving range is It is characterized by having an elongation-restricting sheet member which is not overlapped with the peripheral area but is overlapped with and integrated with the target driving range .
In order to achieve the above object, still another scouring suppression sheet of the present invention is a scouring suppression sheet that is laid on the waterbed ground on which piles are driven and suppresses scouring of the waterbed ground, and is water permeable. and a state in which the target placement range is tense when the pile penetrates the target placement range of the water-permeable sheet member and is placed in the submerged ground. and a partition frame surrounding the target placement range.
In order to achieve the above object, still another scouring suppression sheet of the present invention is a scouring suppression sheet that is laid on the waterbed ground on which piles are driven and suppresses scouring of the waterbed ground, and is water permeable. a water-permeable sheet member having elasticity, and an elongation-restricting sheet member superimposed and integrated in a target placement range of the water-permeable sheet member through which the pile is driven, and It is characterized by having a partition frame portion surrounding the target range.

According to the present invention, by penetrating the pile through the scouring suppression sheet laid on the waterbed ground and driving the pile into the waterbed ground, the scouring suppression sheet is applied to the surrounding area of the pile from the time the pile is driven into the waterbed ground. can suppress the scouring of the submerged ground. Furthermore, since the scouring suppression sheet has water permeability, it is possible to suppress an increase in the lifting pressure of the scouring suppression sheet laid on the waterbed ground, and the scouring suppression sheet is less likely to float from the waterbed ground. Therefore, it is possible to effectively suppress scouring of the submerged ground on which the piles are driven, although it has a simple structure.

Furthermore, according to the former scouring suppression method and scouring suppression sheet, when the pile is driven into the waterbed ground by penetrating the target placement range of the scouring suppression sheet, the target placement range is kept in a tense state. By doing so, it becomes easier to smoothly penetrate the pile into the placement target range of the scouring suppression sheet. According to the latter scouring suppression method and scouring suppression sheet, the elongation suppression sheet member is superimposed and integrated in the target driving range where the pile of the water-permeable sheet member constituting the scouring suppression sheet is driven through. As a result, when the pile is driven through the scouring suppression sheet, the elongation suppression sheet member suppresses the expansion of the target placement range of the scouring suppression sheet. Therefore, it becomes easier to smoothly penetrate the pile into the target placement range of the scouring suppression sheet.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing which illustrates the state which the scour-suppression sheet|seat of embodiment which concerns on this invention was laid in the peripheral area|region of a pile by the longitudinal cross-sectional view. It is explanatory drawing which expands the scouring suppression sheet|seat of FIG. 1, and illustrates it by a vertical cross-sectional view. It is explanatory drawing which illustrates the scour-suppression sheet|seat of FIG. 1 by the cross-sectional view. It is explanatory drawing which illustrates the state before driving a pile of the scour-suppression sheet|seat of FIG. 1 by planar view. It is explanatory drawing which illustrates the state which penetrated the scouring suppression sheet from the state of FIG. 4, and drove the pile in the cross-sectional view. It is explanatory drawing which illustrates another embodiment of the scouring suppression body installed in the pile by the cross-sectional view. FIG. 10 is an explanatory diagram illustrating, in a cross-sectional view, a state in which a scour-suppressing sheet of another embodiment according to the present invention is laid on a peripheral region of a pile; It is explanatory drawing which illustrates the state before driving a pile of the scour-suppression sheet|seat of FIG. 7 by planar view.

BEST MODE FOR CARRYING OUT THE INVENTION The scour suppression method and the scour suppression sheet of the present invention will be described below based on the embodiments shown in the drawings.

The scouring suppression sheet 1 of the present invention illustrated in FIGS. 1 to 5 is laid on the waterbed ground G on which the piles 30 are driven to suppress scouring of the waterbed ground G. FIG. As shown in FIG. 1, this embodiment exemplifies a scour suppression sheet 1 applied to a waterbed ground G in which piles 30 serving as the foundation of an offshore wind turbine generator 20 are driven. The offshore wind turbine generator 20 is constructed by driving the piles 30 into the submerged ground G using a pile driver such as a hydraulic hammer, and then fixing an upper structure 40 having a wind turbine on top of the piles 30 .

As shown in FIGS. 2 and 3, in this scouring suppression method, the scouring suppression sheet 1 having water permeability is laid on the submerged ground G, and the pile 30 penetrates the target placement range of the scouring suppression sheet 1. and cast it into the water bottom ground G. In this embodiment, the scouring suppressor 10 is further installed at the root portion of the pile 30 on the water bottom G after driving the pile 30 into the water bottom G. As shown in FIG.

The scouring suppression sheet 1 comprises a water permeable sheet member 2 having water permeability and an elongation suppression sheet member 3 which is superimposed and integrated in the target driving range of the water permeable sheet member 2 through which the pile 30 is driven. and The scouring suppression sheet 1 further maintains the tension to keep the target placement range in a tense state when the pile 30 penetrates the target placement range of the water-permeable sheet member 2 and is placed in the submerged ground G. have a structure. The target placement range of the anti-scouring sheet 1 is set at the center of the anti-scouring sheet 1 .

The water-permeable sheet member 2 and the elongation-suppressing sheet member 3 are made of, for example, a cloth material or a mesh material having fine meshes to the extent that earth and sand of the waterbed ground G cannot pass through. The elongation-suppressing sheet member 3 is composed of a sheet member having lower stretchability than the water-permeable sheet member 2 . It is preferable that the elongation-suppressing sheet member 3 is made of a non-stretchable sheet member.

If the water-permeable sheet member 2 is stretchable, the water-permeable sheet member 2 alone may cause unintended elongation or twisting when the piles 30 are penetrated, and the piles 30 may be deformed. may be difficult to smoothly penetrate the water-permeable sheet member 2 . Therefore, the elongation suppression sheet member 3 that suppresses the elongation of the water permeable sheet member 2 in the target placement range when the pile 30 is driven through the target placement range of the scouring suppression sheet 1 and is driven into the submerged ground G. , are overlapped and integrated with the target placement range of the water-permeable sheet member 2 . In this embodiment, the water-permeable sheet member 2 and the elongation-restricting sheet member 3 are stitched together to be integrated. can also The elongation-suppressing sheet member 3 also functions as a tension-maintaining structure that keeps the target placement range of the scour-suppressing sheet 1 in a tense state when the pile 30 described above is driven.

In this embodiment, as a tension maintaining structure, a partition frame portion 4 surrounding the target placement range of the scouring suppression sheet 1 is further provided. In this embodiment, belt-shaped belts as the partition frame part 4 are annularly arranged in plan view so as to surround the target placement range of the scouring suppression sheet 1 . The partition frame portion 4 (belt) of this embodiment is sewn to the water permeable sheet member 2 and the stretch-restricting sheet member 3 to be integrated with the water-permeable sheet member 2 and the stretch restraint sheet member 3 .

A peripheral edge portion 5 for suppressing twisting of the scouring suppression sheet 1 is provided at the peripheral edge of the scouring suppression sheet 1 . In this embodiment, a band-shaped belt as the peripheral edge portion 5 is sewn to the peripheral edge of the scour-suppressing sheet 1 (water-permeable sheet member 2) in an annular shape in a plan view to be integrated.

A connecting portion 6 capable of connecting a weight member 7 is provided in each of the partition frame portion 4 and the peripheral edge portion 5 . In this embodiment, a metal chain is used as the weight member 7 , and the weight member 7 (chain) is connected to the connecting portion 6 by the connecting tool 8 . The connecting part 6 can be optionally provided. For example, the connecting portion 6 can be provided on only one of the partition frame portion 4 and the peripheral edge portion 5 . The partition frame portion 4 and the peripheral edge portion 5 are not limited to belt-shaped belts, and may be formed of, for example, plate-shaped members or rod-shaped members. As shown in FIG. 4, radial slits 9 are formed in the target placement range of the scour-suppressing sheet 1 so that the piles 30 can easily pass through. Slits 9 can be optionally provided.

The scouring suppression body 10 has a main body portion 11 having a porous structure that has water permeability and suppresses the passage of earth and sand of the water bottom ground G. The body portion 11 is annularly fitted around the root portion of the pile 30 on the submerged ground G. As shown in FIG. The scouring suppression body 10 of this embodiment further has a string-like body 12 that tightens the main body 11 to the pile 30 .

The porous structure of the main body 11 is preferably a structure in which a large number of voids are intricately arranged. The body portion 11 is formed of, for example, a mesh member. More specifically, the main body 11 is formed by, for example, rolling a sheet-like net-like member into a roll. When the main body portion 11 has the structure described above, the meshes of the overlapping mesh members are wound so as to be shifted from each other, and the sheet-like mesh members overlap, for example, 5 layers or more, preferably 10 layers or more, more preferably 30 layers or more. A structure is preferred.

The main body 11 can also be formed of, for example, a net-like member (three-dimensional net-like resin material) in which thread-like resins are three-dimensionally entwined. In addition, the main body 11 can also be configured to have, for example, a tubular annular bag member formed of a mesh member and a core member formed of a mesh member and filled in the bag member. . The material forming the main body part 11 is not particularly limited, but for example, it may be formed of synthetic fibers such as polyester, polypropylene, and polyethylene.

In this embodiment, the columnar main body 11 is exemplified, but the main body 11 may have any shape as long as it can be annularly fitted around the pile 30, and may be other shapes such as a polygonal columnar shape, a cylindrical shape, and a polygonal cylindrical shape. can also have the shape of It is preferable that the specific gravity of the body portion 11 is higher than the specific gravity of the water (freshwater or seawater) in the water area in which the pile 30 is driven. Specifically, the specific gravity of the body portion 11 is preferably 1.05 or more, more preferably 1.20 or more. When the body portion 11 is made of a material having a relatively small specific gravity, a weight may be provided on the body portion 11 to adjust the specific gravity.

Next, the working procedure of the scouring suppression method using the scouring suppression sheet 1 will be described.

As shown in FIG. 4 , the scouring suppression sheet 1 is lowered toward the water bottom ground G using a lifting jig or the like, and the scouring suppression sheet 1 is laid on the water bottom ground G. As shown in FIG. Next, as shown in FIG. 5, a weight member 7 is installed on the scouring suppression sheet 1 to fix the scouring suppression sheet 1 on the water bottom ground G. As shown in FIG. In this embodiment, a chain as a weight member 7 is connected by a connector 8 to a connecting portion 6 provided on the partition frame portion 4 and the peripheral edge portion 5 . For example, the weight member 7 may be connected to the scouring suppression sheet 1 in advance on land or on a ship, and the scouring suppression sheet 1 with the weight member 7 coupled may be laid on the waterbed ground G.

Next, the pile 30 is driven into the submerged ground G by penetrating the target driving range of the scour-suppressing sheet 1 where the water-permeable sheet member 2 and the elongation-suppressing sheet member 3 overlap. When the pile 30 penetrates the target placement range of the scouring suppression sheet 1, the target placement range of the scouring suppression sheet 1 (the target placement range of the water-permeable sheet member 2 and the elongation suppression sheet member 3) is tensioned. to the state where In this embodiment, the outer periphery of the target placement range of the scouring suppression sheet 1 is constrained by the partition frame portion 4, so that when the pile 30 is penetrated into the target placement range of the scouring suppression sheet 1, The target placement range of the scour-suppressing sheet 1 is maintained in a tense state. Furthermore, the elongation of the water-permeable sheet member 2 in the target setting range is suppressed by the elongation-suppressing sheet member 3 .

After driving the piles 30, the scouring suppressor 10 is installed at the base of the piles 30 on the waterbed ground G, as shown in FIGS. Specifically, the main body part 11 is annularly fitted around the root portion of the pile 30 on the submerged ground G. As shown in FIG. In this embodiment, the columnar main body 11 is annularly fitted around the outer circumference of the pile 30, and the main body 11 is tightened to the pile 30 by the string-like body 12, which is annularly wound around the outer circumference of the main body 11. The ends of the shaped body 12 are fixed by fixtures 13 . The strength with which the main body 11 is tightened by the string-like body 12 is such that the main body 11 naturally descends under its own weight to a position where the main body 11 abuts on the submerged ground G while maintaining the state in which the main body 11 is in contact with the outer peripheral surface of the pile 30. It is recommended to set the strength to the extent that it does.

As described above, in the present invention, the piles 30 are driven through the scouring suppression sheet 1 laid on the waterbed ground G, and the piles 30 are driven into the waterbed ground G. The excavation suppression sheet 1 can suppress scouring of the water bottom ground G in the area around the pile 30 . Furthermore, since the scouring suppression sheet 1 has water permeability, it is possible to suppress an increase in the lifting force of the scouring suppression sheet 1 laid on the waterbed ground G, and the scouring suppression sheet 1 floats from the waterbed ground G. it gets harder. By using the scouring suppression sheet 1 having water permeability, it becomes easy to carry out the work of suspending the scouring suppression sheet 1 toward the waterbed ground G using a lifting jig or the like. Further, when the piles 30 are penetrated through the scouring suppression sheet 1, a part of the scouring suppression sheet 1 follows the piles 30 and is inserted into the submerged ground G. A gap is less likely to occur between the outer peripheral surface of the scouring suppression sheet 30 and the inner peripheral edge of the through hole of the scouring suppression sheet 1 . Therefore, it is possible to effectively suppress scouring of the water bottom ground G in which the piles 30 are driven, although it has a simple configuration.

When the pile 30 is driven through the target placement range of the scouring suppression sheet 1 and is driven into the submerged ground G, if the target placement range of the scouring suppression sheet 1 is set in a tense state, the scouring suppression sheet 1 will be removed. It becomes easier to smoothly penetrate the pile 30 into the driving target range. Accordingly, it is possible to prevent the scouring suppression sheet 1 from being unintentionally shifted or twisted after driving the pile 30 .

If the scouring suppression sheet 1 is configured to have the elongation suppression sheet member 3 that is superimposed and integrated in the target placement range of the water permeable sheet member 2, when the pile 30 is penetrated through the scouring suppression sheet 1, the water permeability is reduced. The elongation-suppressing sheet member 3 having lower stretchability than the elastic sheet member 2 can suppress elongation of the target driving range of the water-permeable sheet member 2 . Therefore, it becomes easier for the piles 30 to penetrate the target placement range of the scouring suppression sheet 1 more smoothly.

When the scouring suppression sheet 1 is provided with the partition frame portion 4, the outer periphery of the scouring suppression sheet 1 placement target range is constrained by the partition frame portion 4, so that the piles 30 are placed within the scouring suppression sheet 1 placement target. When the scouring suppression sheet 1 is penetrated through the range, the target placement range of the scouring suppression sheet 1 is maintained in a stretched state. Therefore, it becomes easier to smoothly penetrate the pile 30 through the scouring suppression sheet 1 . In addition, by providing the partition frame 4, when the pile 30 is penetrated through the scouring suppression sheet 1, the crack generated in the target placement range of the scouring suppression sheet 1 spreads outside the partition frame 4. can be dammed. Furthermore, when the connecting portion 6 is provided in the partition frame portion 4, the weight member 7 is connected to the connecting portion 6 of the partition frame portion 4, so that when the pile 30 is penetrated through the scour suppression sheet 1, the partition frame portion 4 positional deviation can be suppressed. Therefore, the target placement range of the anti-scouring sheet 1 can be more reliably maintained in a tense state.

When the scouring suppression sheet 1 is provided with the peripheral portion 5, the scouring suppression sheet 1 can be stably and easily laid in the water. Further, when the connecting portion 6 is provided on the peripheral edge portion 5, by connecting the weight member 7 to the connecting portion 6 of the peripheral edge portion 5, the anti-scouring sheet 1 is less likely to sway in the water, and the anti-scouring sheet 1 is laid further. becomes easier. In addition, the anti-scouring sheet 1 can be prevented from loosening or floating in water, which is more advantageous for suppressing the scattering of bottom sediment by the anti-scouring sheet 1 .

If there is a gap between the outer peripheral surface of the pile 30 and the inner peripheral edge of the through hole of the scouring suppression sheet 1, the scouring suppression body 10 can be installed at the root portion of the pile 30 as in this embodiment. Then, the gap can be closed quickly. Furthermore, by fitting the main body 11, which has water permeability and has a porous structure, to the base portion of the pile 30 on the submerged ground G in an annular manner, the downward flow caused by the water flow hitting the pile 30 is generated in the main body 11. It flows into the porous structure and is effectively damped, making it difficult for horseshoe vortices and trailing vortices to occur near the root of the pile 30 . Therefore, it becomes more and more advantageous to suppress scouring in the peripheral area of the pile 30 .

In the above, the case where the scouring suppression body 10 is wound after driving the pile 30 into the waterbed ground G is exemplified. The pile 30 with the suppressor 10 attached can also be driven into the submerged ground G. In this case, the scouring suppression body 10 is attached to the pile 30 before driving so that the scouring suppression body 10 is positioned at the root portion of the pile 30 on the waterbed ground G when the pile 30 has been driven. Set the installation position.

The scour suppression body 10 can also be configured as illustrated in FIG. 6, for example. The body portion 11 of this embodiment is formed in a tubular shape through which the string-like body 12 can be inserted. The body portion 11 is composed of a plurality of divided bodies 11a. A string-like body 12 is inserted through the through hole 14 of each divided body 11a, and the plurality of divided bodies 11a are connected by the string-shaped body 12. As shown in FIG.

7 and 8 illustrate still another embodiment of the scour-suppressing structure using the scour-suppressing sheet 1. FIG. This embodiment differs from the embodiments illustrated in FIGS. 1 to 5 in the construction of the scour-suppressing sheet 1 and the weight member 7 . The scouring suppression sheet 1 of this embodiment is not provided with the partition frame portion 4 and the peripheral edge portion 5 . In this embodiment, the scouring suppression sheet 1 is fixed on the water bottom ground G by placing a bag stuffed with stones as the weight member 7 on the periphery of the scouring suppression sheet 1 . Furthermore, when the pile 30 is driven through the target placement range of the scouring suppression sheet 1 and driven into the submerged ground G, the scouring suppression sheet 1 is placed in a tensioned target placement range. A bag stuffed with stones is placed as a weight member 7 on the scouring suppression sheet 1 so as to surround the target placement range of the suppression sheet 1 .

In this way, by installing the weight member 7 so as to surround the target placement range of the scouring suppression sheet 1, the pile 30 is driven through the target placement range of the scouring suppression sheet 1 and placed in the waterbed ground G. When doing so, the outer circumference of the target placement range of the scour-suppressing sheet 1 is constrained by the weight member 7 . Therefore, the target placement range of the scouring suppression sheet 1 can be maintained in a tense state, and the pile 30 can be smoothly penetrated into the target placement range of the scouring suppression sheet 1 .

The scouring suppression sheet 1 can be installed not only on the piles 30 constituting the offshore wind turbine generator 20 but also on other piles 30 driven into the waterbed ground G. In the above-exemplified embodiment, the scour-suppressing sheet 1 having the elongation-suppressing sheet member 3 is exemplified. A configuration without 3 is also possible.

1 Scouring suppression sheet 2 Permeable sheet member 3 Stretch suppression sheet member 4 Partition frame 5 Peripheral edge 6 Connection 7 Weight member 8 Connector 9 Slit 10 Scouring suppression body 11 Main body 11a Divided body 12 String-like body 13 Fixed Tool 14 Through-hole 20 Offshore wind turbine generator 30 Pile 40 Upper structure G Submerged ground

Claims (8)

In the scouring suppression method for suppressing scouring of the submerged ground where piles are driven,
When a scouring suppression sheet having water permeability is laid on the waterbed ground, and the pile is driven into the waterbed ground by penetrating the scouring suppression sheet into the target placement range, the target placement range is set. A method of suppressing scouring, characterized by creating a tense state. In the scouring suppression method for suppressing scouring of the submerged ground where piles are driven,
A scour-suppressing sheet comprising a water-permeable sheet member having water permeability and an elongation-suppressing sheet member superimposed and integrated in a target driving range of the water-permeable sheet member to be driven through the pile. A method for suppressing scouring, wherein the pile is laid on the ground, and the pile is driven into the submerged ground by penetrating the target driving range of the water-permeable sheet member and the elongation-restricting sheet. When driving the pile into the underwater ground by penetrating the target driving range of the water-permeable sheet member and the elongation-restricting sheet member, the target driving range of the water-permeable sheet member and the elongation-restricting sheet The scouring suppression method according to claim 2, wherein the members are kept in tension. The main body, which constitutes the scouring suppression body and has water permeability and has a porous structure that suppresses the passage of earth and sand in the waterbed ground, is annularly fitted around the root portion of the pile on the waterbed ground. The scour suppression method according to any one of claims 1 to 3. A scouring suppression sheet for suppressing scouring of the waterbed ground laid on the waterbed ground on which piles are driven,
It has a water-permeable sheet member having water permeability, and when the pile penetrates the target driving range of the water-permeable sheet member and is driven into the underwater ground, a part of the water-permeable sheet member A scouring suppression sheet characterized by having a tension maintaining structure that makes the target placement range, which is the area of the water-permeable sheet member, more tense than the surrounding area of the target placement range . A scouring suppression sheet for suppressing scouring of the waterbed ground laid on the waterbed ground on which piles are driven,
A water-permeable sheet member having water permeability is provided, and a partial area of the water-permeable sheet member is set in advance as a target driving range in which the pile is driven through, and the driving target is set. A scour-suppressing sheet , comprising an elongation-suppressing sheet member that is integrated with and overlapped with the target placement area without being overlapped with a peripheral area of the area . A scouring suppression sheet for suppressing scouring of the waterbed ground by laying on the waterbed ground on which piles are driven, the scouring suppression sheet comprising a water-permeable sheet member having water permeability, and the piles being the water-permeable water-permeable sheet. A partition surrounding the target placement range has a tension maintaining structure that keeps the target placement range in a tense state when the sheet member penetrates the target placement range and is placed in the submerged ground. An anti-scouring sheet characterized by having a frame. A scouring suppression sheet for suppressing scouring of the waterbed ground laid on the waterbed ground on which piles are driven,
A water-permeable sheet member having water permeability, and an elongation-restricting sheet member superimposed and integrated in a target driving range of the water-permeable sheet member through which the pile is driven, and A scouring suppression sheet characterized by having a partition frame surrounding a target range.

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