JP2008267103A - Erosion prevention method of seashore and shore embankment block used for same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for preventing the erosion of a seashore by controlling the movement of earth and sand of a coast in a predominant direction by waves, and also to provide a shore embankment block used for the same. <P>SOLUTION: The shore embankment block comprises an upper projecting part and a lower pedestal part. The shore embankment block is configured to have at an upper surface a plate shaped or a pillar shaped projected part with a pair of the flank angle surfaces of water current which are formed in such a way that both sides linked to one back surface form a tapered flat shape in order to make the water current direct in one direction by bending the water current due to the coming and drawing of the waves in the upper projecting part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a coastal erosion prevention method that protects a coast from erosion and a revetment block used therein.

  There are various causes of erosion on the coast, but the movement of sediment in the prevailing direction by waves is a fundamental factor. Conventionally, as countermeasures to prevent this, countermeasures have been taken such as providing a jetty or a breakwater, or building a tetrapod or similar revetment block on the beach. It was.

  In this specification, “movement of earth and sand in the prevailing direction” means a phenomenon in which earth and sand move in that direction along the coast due to prevailing winds (wind that blows particularly in a certain direction at a certain place) ( It shall refer to the direction of the arrow in FIG. The movement of earth and sand in that direction is referred to as “excellent movement” (claim 1).

  The direction of waves that hit the coast varies depending on the weather and geographical factors, but when the wave direction becomes oblique with respect to the normal direction to the shoreline, a coastal sand drift phenomenon occurs in which sediment moves in the coastal direction. Further, in this specification, the “coast line” refers to a line parallel to the shoreline.

  There was a problem that the erosion of other coasts on the lower side became intensified if a wave blocking area was formed by construction of a breakwater or the movement of coastal sediment was blocked.

  Moreover, due to coastal erosion, the Ministry of Land, Infrastructure, Transport and Tourism estimates that 160 ha of land is lost annually, causing serious damage. In places where erosion is severe, erosion prevention measures are an important and urgent issue in terms of national land conservation, which protects coastal land.

  In view of the above situation, the present invention has an object to provide a method for preventing coastal erosion by controlling movement of coastal sediment in the prevailing direction due to waves, and a revetment block used therefor. did.

  In order to solve the above-described problems, the present invention provides a plate-like or column-like shape having a pair of side surfaces having a clearance angle in one direction with respect to a water flow caused by a wave dragging motion on the seabed and shore area in the vicinity of the coastline. The revetment block with the protrusions of the top surface is regularly arranged in a group so that the flank angle of the protrusions is on the side of the precipitous movement of coastal drift sand, and the protrusions are refracted It is characterized in that the water flow containing the cut-out earth and sand is sequentially sent to the relief angle surface of the subsequent protrusion in the group, and the coastal drift sand is reversely transferred in the direction of prevailing movement by the action of the natural force of waves. Provide coastal erosion prevention methods.

  In addition, the present invention comprises an upper protrusion and a lower pedestal, and the upper protrusion is unidirectional in order to refract the water flow caused by the wave pulling and move in one direction. A revetment block provided with a plate-like or column-like protrusion having a relief angle surface for a pair of water streams formed on the upper surface so that the side surfaces on both sides connected to the back surface are narrowed at the front. I will provide a.

  Since the present invention is as described above, when a wave passes over a structure installed by knitting a group in the vicinity of the shoreline, the clearance angle surface of the protruding portion provided on the upper surface of the revetment block is basically used. By repeating the flow of water containing earth and sand to the clearance angle surface of the following protrusion from the earth, the earth and sand trying to move in the dominant direction is returned in the opposite direction.

  If there is a prevailing coastal drift that promotes erosion, this movement will be offset, and if there is a sediment source such as an estuary, the sediment will be transferred to the upper side by the natural force of waves by installing it from that location. It is also possible.

  In addition, erosion prevention is effective by adjusting the clearance angle and dimensions of the upper protrusion and the number of arrangements appropriately at the time of creation and after installation according to the ocean characteristics such as the wave characteristics, topography, substrate, etc. It becomes possible to control to.

  As described above, according to the present invention, by arranging the revetment block formed on the upper surface with a protrusion having a relief angle surface against the water flow by the wave pulling movement, regularly or almost regularly, Since the water flow containing earth and sand is sent in the direction in which the earth and sand moves predominantly, the earth and sand are locally introduced into the shielding area that occurs when the wave shielding area is formed, such as conventional breakwaters and seawalls. It does not pile up, spreads earth and sand all over the installation site, and has an excellent effect of being able to rationally prevent coastal erosion.

  In addition, when the structure according to the present invention is constructed in the sea, the intra-group space where the projecting portion having a relief angle surface stands from the bottom of the sea has good tide, and the sun also shines sufficiently. As a raw substrate, seaweed beds are created and a seabed environment with high productivity of useful seafood can be provided.

  FIG. 1 shows an embodiment of a revetment block used in the method of the present invention. In this embodiment, when there is one protrusion, (a) is a plan view, (b) is an elevation view (front view), (c) is a side view, and (d) is a perspective view.

  The revetment block B is composed of an upper protrusion 1 and a lower pedestal 2, and the upper protrusion 1 refracts the water flow due to the wave pulling and moves in one direction. A plate-like or columnar protrusion 1 having a pair of water flow relief angle surfaces 4, 4 formed so that side surfaces 4, 4 on both sides connected to one back surface 3 are narrowed at the front is formed on the upper surface. It is provided and configured.

  FIG. 2 is an explanatory plan view showing the principle of the present invention. As shown in FIG. 2, the arrangement of the revetment block B that receives a spilled water flow at one clearance angle surface 4 and receives a spilled water flow at another clearance angle surface 4, The back-and-forth motion is refracted at the clearance angle surface, and all flows in one direction, and the moving earth and sand is also transferred in one direction.

  FIG. 3 is an explanatory plan view for explaining the effect of the present invention. (A) is a model of sediment movement on a natural coast, (b) is a model of sediment movement of a conventional facility example, (c) is a sample of the facility example of the present invention. It is a figure explaining the earth and sand movement model.

  In the natural coast of Fig. 3 (a), if there is a wave that is incident obliquely, the sand particles along the path from the shoreline A point to B point and then to the point D point along with the water flow by the wave. As a result, the earth and sand that were at point A in the coastal direction move to point D. This movement is repeated by repeated wave pulling, and the earth and sand move in the coastal direction.

  The same applies to the conventional revetment facility area of FIG.

  FIG. 3 (c) is a revetment facility according to the method of the present invention. According to this, the sediment particles at the shoreline A point hit the clearance angle surface of the protruding portion of the block upper surface at the B1 point and are shown in FIG. According to the principle, the course is refracted and sent to the clearance angle surfaces of the subsequent B2 and B3 one after another and goes up.

  When pulling wave force acts at the C1 point, it flows down in the shoreline direction. In this case as well, according to the principle shown in FIG. 2, the sand particles are refracted on the clearance angle planes of C2 and C3 and reach the shoreline at the D point. As a result, the sediment particles at point A move to point D in the coastal direction opposite to that of the natural coast and the conventional facility.

  This movement is also repeated due to repeated wave pulling, and the earth and sand is sent back by the natural force of the waves in the direction of prevailing movement, so the drifting phenomenon is controlled to be offset and coastal erosion can be prevented.

  4 to 6 are plan views of the projecting portions 1 of the revetment block according to the present invention, and FIG. 4 is an isosceles triangle or a flat shape in which the projecting portion is one side of the rear surface when viewed from the plane. It is characterized by being an isosceles triangle. FIG. 5 is characterized in that, as viewed from the plane, the protruding portion is curved inward in the horizontal direction on the other two sides of the triangle with the back side as one side. FIG. 6 is characterized in that the protrusion as seen from the plane is a trapezoid in which the vertices of the other two sides of the triangle having the back side as one side are cut out.

  7 to 9 show other embodiments of the revetment block according to the present invention, in which (a) is a plan view, (b) is an elevation view, and (c) is a side view. . Although FIG. 7 has one protrusion, it differs from that of FIG. 1 in that the structure of the lower pedestal and the protrusion are located approximately in the center of the pedestal. FIG. 8 shows an embodiment in which there are two protrusions, and FIG. 9 shows an example in which there are three protrusions.

  The projecting portion and the pedestal portion described above are formed by integral molding, and after being formed as separate parts, they are joined and integrated by a fitting method, a coupling method, or an adhesion method.

  FIG. 10 to FIG. 14 are explanatory diagrams showing the above-described revetment blocks arranged in the seabed near the coastline, the shore area, or an existing coastal structure.

  FIG. 10 is a perspective view showing the embodiment revetment block shown in FIG. 1 in an array, FIG. 11 is a view showing the embodiment block arranged in a slanted structure, and FIG. The plane arrangement view and FIG. 4B are schematic cross-sectional views thereof.

  FIGS. 12A and 12B are diagrams showing the embodiment revetment blocks shown in FIG. 7 arranged in another gently inclined lantern structure, in which FIG. 12A is a plan view thereof, and FIG. 12B is a schematic cross-sectional view thereof.

  FIG. 13 is a plan arrangement view of a revetment structure in which the embodiment blocks having two protrusions shown in FIG. 8 are arranged on the seabed, on the shore area, or on an existing coastal structure.

  FIG. 14 is a plane arrangement view (FIG. (A)) and a schematic cross-sectional view (FIG. (B)) of the sand drift control structure in which the embodiment block having three protrusions shown in FIG. 9 is installed on the seabed. is there.

  FIG. 15 is a perspective explanatory view showing a system in which the revetment block B shown in FIG. 1 is arranged from below the breakwater H and only the protruding portion 1 of the revetment block is joined to the breakwater as the breakwater rises. is there.

  FIG. 16 shows a revetment block B according to still another embodiment, wherein (a) is a plan view, (b) is a side view, (c) is an elevation view, and (d) is a perspective view. As shown in the figure, the revetment block B is formed with a pedestal portion 2 that is long on one side, and has three protruding portions 1, 1 and 1 projecting from it at intervals.

  And in the position between the protrusion parts 1 and 1, in the base part 2, by providing the concave notches 5 and 5 on both sides, insertion teeth 6, 6 and 6 are formed between them, and the insertion teeth 6 and the concave notches 5 are The trapezoid is formed in a shape that fits with each other. Further, when the revetment blocks B, B are connected in series, semi-recessed openings 5a, 5a are provided so that a recessed notch having the same shape as the recessed notch 5 is formed between them. Further, lateral pin holes 9, 9, 9 through which the connecting pins 7, 7 pass directly are provided in the insertion teeth 6, 6, 6 on both sides.

  17A and 17B are diagrams showing the revetment blocks B shown in FIG. 16 arranged in a gently inclined bank structure, where FIG. 17A is a plan view thereof and FIG. 17B is a schematic cross-sectional view thereof. Although the direction of the revetment block B is the same in the arrangement type of the gently inclined bank structure, a large number of arrangements are made both vertically and horizontally, and in the staggered staggered arrangement, the recessed notches 5, 5,. In the state where 6, 6,... Are combined, the connecting pins 7, 7,... Are passed through the respective side pin holes 9, 9,. Therefore, the connecting pins 7, 7,... Connect the vertical and horizontal revetment blocks B, B, .., and all the revetment blocks B, B,. Will not break (see (b) of the figure)

  FIG. 18 shows an arrangement in which only the projecting portion 1 is fixed to the ground of the revetment block according to another embodiment, and the projecting portion 1 is formed by penetrating the vertical pile holes 10, 10, 10 on the lower surface at each corner portion. It is. Therefore, by driving pile-like objects (including pin-like objects) 11, 11, 11 into the vertical pile holes 10, 10, 10 into the ground (or the seabed), it is ensured that the protrusion 1 will not fall down. An array can be held.

  As shown in FIG. 10 to FIG. 16 and FIG. 18, the seabed and the coastal area near the coastline have a pair of side surfaces having a clearance angle in one direction with respect to the water flow caused by the wave dragging motion. A revetment block with plate-like or columnar protrusions on the top is regularly arranged so that the relief angle of the protrusions is on the side where prevailing movement of coastal drifting sand occurs, and the protrusions are refracted. The water flow containing the earth and sand that has been cut through is sequentially sent to the relief angle surface of the subsequent protrusion in the group, and the coastal drift sand is reversely transferred in the direction of prevailing movement by the action of the natural force of waves, It is possible to effectively prevent coastal erosion.

  In particular, as shown in FIG. 15, the same operation and effect can be obtained by joining and arranging only the protruding portions of the revetment block according to the embodiment of the present invention on an existing coastal structure.

It is one Example of the revetment block used for this invention method, (a) is a top view, (b) is an elevation view, (c) is a side view, (d) is a perspective view. FIG. 2 is an explanatory plan view showing the principle of the present invention. It is plane explanatory drawing for demonstrating the effect by this invention, (a) is an earth-sand movement model explanatory drawing of a natural coast, (b) is an earth-and-sand movement model explanatory drawing of the example of a conventional facility, (c) is an example of this invention facility. The earth and sand model explanatory drawing. The top view explaining one Example protrusion part of this invention revetment block. The top view explaining the other Example protrusion part. The top view explaining another Example protrusion part. The other example revetment block of this invention is demonstrated, (a) is a top view, (b) is an elevation, (c) is a side view. FIG. 4 is a diagram illustrating another revetment block according to the present invention, in which (a) is a plan view, (b) is an elevation view, and (c) is a side view. FIG. 6 is a diagram for explaining another revetment block according to the present invention, in which (a) is a plan view, (b) is an elevation view, and (c) is a side view. The perspective view which arranged and showed the example revetment block shown in FIG. It is the perspective view which arranged and showed the block of the Example in the slanting structure, (a) is the plane arrangement | sequence figure, (b) is the cross-sectional schematic diagram. It is the figure which arranged and showed the example revetment block shown in FIG. 7 in the other gently inclined lantern structure, (a) is the plane arrangement | sequence figure, (b) is the cross-sectional schematic diagram. FIG. 9 is a plan arrangement view of a revetment structure in which the embodiment blocks having two protrusions shown in FIG. 8 are arranged on the seabed, the shore area, or an existing coastal structure. The plane arrangement figure (the figure (a)) and the cross-sectional schematic diagram (the figure (b)) of the sand drift control structure which installed the Example block which has three protrusion parts shown in FIG. 9 in the seabed. The perspective explanatory view which showed the system which joins only the protrusion part of a breakwater block to a breakwater while arranging the breakwater block shown in FIG. 1 from the downward direction of a breakwater. Furthermore, the revetment block B by another Example is shown, (a) is a top view, (b) is a side view, (c) is an elevation view, (d) is a perspective view. It is the figure which arranged and showed the revetment block shown in FIG. 16 in the gentle slope bank structure, (a) is the plane arrangement | sequence figure, (b) is the cross-sectional schematic diagram. Furthermore, the planar arrangement figure (the figure (a)) of the structure which fixedly arranged only the protrusion part directly to the ground among the revetment blocks by another Example (the figure (a)), a cross-sectional schematic diagram (the figure (b)).

Explanation of symbols

B Revetment block 1 Protruding part 2 Pedestal part 3 Back face 4 Relief angle face (side face)
5 recessed notch 6 insertion tooth 7 connecting pin 9 horizontal pin hole 10 vertical pile hole 11 pile-shaped object

Claims (10)

  A revetment block with a plate-like or columnar protrusion with a pair of side surfaces with a relief angle in one direction against the water flow caused by wave dragging is projected on the seabed and shore near the coastline. The flank angle of the part is regularly arranged so that it is on the side of the precipitous movement of the coastal drift sand, and it is installed in a group, and the water flow including the earth and sand that has been refracted from the protrusion is passed through the group A coastal erosion prevention method characterized in that the coastal drift sand is sent back to the flank angle surface of the protruding portion and reversely transported in the direction of prevailing movement by the action utilizing the natural force of waves.   It consists of an upper protrusion and a lower pedestal, and the upper protrusions are side surfaces on both sides that connect to one back surface in order to refract the water flow caused by the wave-drawing motion and to face one direction. A revetment block characterized in that a plate-like or columnar protrusion having a relief angle surface of a pair of water streams formed so as to form a planar shape constricted at the tip is provided on the upper surface.   The revetment block according to claim 2, wherein the projecting portion is an isosceles triangle or an isosceles triangle having one side with respect to the rear surface when viewed from the plane.   The revetment block according to claim 2, wherein the projecting portion, when viewed from a plane, has two other sides of the triangle with the back side as one side curved inwardly in the horizontal direction.   3. The revetment block according to claim 2, wherein the projecting portion is a trapezoid in which the apex of the other two sides of the triangle with the back side as one side is cut out when viewed from the plane.   The upper projecting portion and the lower pedestal portion are formed by integral molding, or are formed as separate parts, and then joined and integrated by a fitting method, a coupling method, or an adhesion method. Revetment block according to 2, 3, 4 or 5.   The coastal erosion prevention method according to claim 1, wherein the projecting portions according to claim 2, 3, 4, 5 or 6 are joined and arranged to an existing coastal structure.   7. The revetment block according to claim 2, 3, 4, 5, or 6, wherein a concave notch and an insertion tooth having a shape capable of being combined with each other are formed on at least one side surface opposite to the pedestal portion.   7. A lateral pin hole through which a connecting pin is directly passed in the arrangement direction is formed in the pedestal portion so that the arranged revetment blocks can be connected to each other. Or the revetment block according to 8.   A vertical hole through which a pile-like object to be driven into the ground surface is formed from the top to the bottom surface of the projecting portion according to claim 2, 3, 4, 5, or 6, and the pile-like object is driven into the ground through the vertical hole, 2. The coastal erosion prevention method according to claim 1, wherein the portions are fixedly arranged directly on the ground.

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