JPH0656009B2 - Sloping revetment structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is applied to a coastline of a sloping surface with a gentle slope,
It relates to a gently sloping seawall structure that protects the coastline from erosion by waves.

[Prior Art] Naturally sloping surface of a coastline or a gently sloping surface that has been constructed is covered stepwise with a seawall block having a low rising height from the slope surface to reduce the launch height of waves, Japanese Patent Publication No. 60-53130 discloses a sloping revetment structure that weakens wave reflection to reduce wave force and reduces the flow velocity and amount of return flow.

[Problems to be Solved by the Invention] This revetment block is composed of a flat plate-shaped main plate in which an upper sloped surface is formed more loosely than a bottom sloped surface, and ground contact surfaces are formed at the left and right end portions and the middle portion of the bottom sloped surface. In this structure, three rectangular rod-shaped support legs that are substantially parallel to the surface are provided so as to project in parallel, and a through hole for filling is provided between the support legs.

However, in such a sandy beach revetment structure using flat plate blocks, when the flat plate main plate of the revetment block is directly supported by the sand layer on the coast, the supporting sand layer is affected by the water flow of waves from the peripheral part of the block group. The scouring is likely to cause uneven settlement of the revetment block, and the waves are reflected to the front part of the one side that is gradually inclined and lifted up, further promoting scouring and one-sided settlement. Finally, the block may fall and be washed away by the waves.

In this revetment structure, it is said that the inside of the filling hole of the revetment block will be filled with concrete at the place where the waves are rough and the stones and sand will be filled at the place where the waves are weak. Since the inner wall surface is formed in the vertical plane, even if the through holes are filled with sand, the inner sand layer does not contact the lower surface of the flat plate main plate and resists the vertical load of the revetment block. It does not serve as a supportive measure to prevent subsidence.

In order to prevent such unequal settlement of blocks and toppling overflow, it has been proposed to integrally connect adjacent blocks in the front, rear, left, and right with connecting reinforcing bars, but for example, the blocks at the end of the block group are large. When sunk unevenly, it is possible that adjacent blocks may be gradually sunk due to being pulled by this tilting block. It requires labor.

On the other hand, as a revetment structure in which adjacent blocks on the front, rear, left, and right are not connected to each other by connecting rebars but are simply locked, there is a revetment structure disclosed in JP-A-54-100126.

This revetment block extends the upper slab whose top surface is formed into an inclined surface from the upper edge of the rear pillar that hangs down from the rear end edge of the horizontal bottom slab. Between the both sides of the edge, the top surface is connected to the inclined front pillar part that is connected to the top inclined surface of the upper plate, and an inner cavity portion having a square opening is provided on the front surface of the block. A communicating hole is provided on the side of the block, and a locking portion for locking the front locking portion of the upper block is provided on the upper rear end of the block.

However, in such a revetment structure of a sandy beach using a block with a flat bottom plate, when the horizontal bottom plate of the revetment block is supported by a sand layer on the coast, the supporting sand layer is affected by the water current of the waves from the peripheral part of the block group. Uneven settlement of the revetment block is likely to occur due to scouring, and the waves are reflected on the front part of the one side that gradually inclines and rises, further promoting the one-sided settlement and finally the block. May fall and be washed away by the waves.

In addition, in this revetment structure, the block masonry is provided with a cavity that laterally communicates with the inner cavity portion and the lateral through hole at each step, and the cavity portion enters the inner cavity portion through the opening on the front surface of the block. Since the water flow of the generated waves is discharged to the outside of the block masonry from the side through holes, the supporting sand layer of the outermost revetment block is easily washed away by the scour effect of the discharged water flow. . Therefore, the outermost revetment block placed on the supporting sand layer is unevenly settled, and finally the block falls and is washed away. This uneven settlement and runoff progress from the outer block to the inner block in sequence, and the entire revetment structure collapses.

Therefore, it is an object of the present invention to provide a gently sloping revetment structure that is strong against the scouring action due to the water flow of waves and does not cause uneven settlement or overturning of the revetment block even when installed without interconnection.

[Means for Solving the Problem] Hereinafter, the reference symbols in the accompanying drawings will be used to explain in the gently sloping revetment structure of the present invention, a columnar or prismatic shaft at the center of the lower end of the inverted truncated cone or inverted truncated pyramid body 2. The leg 3 is projected,
When covering a gently sloped surface 6 such as a shoreline with a revetment block 1 in which a one-sided inclined surface 5 is formed on the upper surface of a circular or rectangular head 4 of the body 2, the shaft leg 3 of each revetment block 1 is gently sloped. 6 is inserted vertically and the shaft leg 3 and the body 2 are embedded in the gently inclined surface 6, and the one-way inclined surface 5 of the head 4 of each revetment block 1 is arranged along the gently inclined surface 6. Between the heads 4 and 4 of the revetment blocks 1 and 1 laid so that the side surfaces of 4 contact each other, an uncovered area 11 communicating with the sand layer ground supporting each body 2 is provided, and sand or crushed stone is provided in the uncovered area 11. Etc. are filled to provide a water-permeable filling layer.

[Operation] The revetment blocks 1 and 1 are laid adjacent to each other in the front, rear, left, and right to cover the gently sloped surface 6, but normally, the whole of the shaft leg 3 to the head of the body 2 is gently sloped 6. Buried in.
Therefore, the waves hitting the coastline gently go up in the state where the wave force is attenuated along each unidirectional slope 5 of the revetment block group without largely reflecting at the revetment block row and splashing the waves. Most of the return water flow of the launch wave circulates to the sea surface along the one-way inclined surface 5 of the block group, and a part of the return water flow head 4 of the revetment block 1,1.
It penetrates into the intermediate layer of sand, crushed stone, etc. in the uncovered area 11 left between 4 and flows back into the sea through the sand layer ground of the coast. In this process, a part of the sand that accompanies the waves is filtered out by the water-permeable filling layer and sequentially deposited on the uncoated area 11.

The weight of the revetment block 1 is evenly distributed and loaded on the tapered side surface of the body 2, and as shown in FIG. 4, the distributed vertically acting force is F, and the tapered circumference of the body 2 is Assuming that the angle formed by the generatrix of the side surface with respect to the horizontal plane is θ, the side surface of the body 2 has a Fcos θ from the support ground of the sand layer.
Will receive the resistance of. Therefore, assuming that the coefficient of friction of the body surface is μ, the frictional force f ₁ = μF cos θ acts.

Further, since the lateral pressure P from the supporting ground acts on the body 2, the side surface of the body 2 receives a drag force of Pcos θ from the ground,
Friction force f ₂ = μP cos θ acts. Since the lateral pressure P from the ground also acts on the shaft leg 3 arranged vertically, the side surface of the shaft leg 3 receives the drag force P, and the frictional force q = μP acts.

The vertical component (f ₁ + f ₂ ) sin θ of the frictional forces f ₁ and f ₂ suppresses the settlement of the revetment block 1 together with the frictional force q. The shaft leg 3, which is vertically inserted deeply into the support ground of the sand layer, blocks the tapered side surface of the body 2 as well as the unequal subsidence and the one-sided inclination of the revetment block 1.

In the process in which the returning water flow of waves returns to the sea from the uncovered area 11 through the sand layer ground, the sand accompanied by the water flow is filtered out by the permeable filling layer, and remains deposited in the uncovered area 11. Go and prevent uneven settlement of the seawall block 1 and leaning.

[Embodiment] In the embodiment shown in FIGS. 1 to 4, the body 2 has an inverted truncated cone shape, the shaft leg 3 integrally formed with the body 2 has a columnar shape, and the shaft leg 3 has a lower end portion. The conical protrusions 7 are connected in series. The angle θ formed by the generatrix of the tapered side surface of the conical projection 7 with the horizontal plane is the same as the side surface of the body, and the frictional forces f ₁ and f ₂ also act on the side surface of the conical projection 7 to revet the revetment block 1.
It is difficult to sink.

The circular head 4 is composed of a short cylindrical body having the same diameter as the large diameter portion of the upper end of the body 2, and the hanging rebar 8 is provided at the center of the one-way inclined surface 5.
The base end bent part of is embedded and fixed. In the illustrated laying mode, the front, rear, left and right revetment blocks 1, 1 are connected to each other by welding a horizontal reinforcing bar 9 and a vertical reinforcing bar 10 to the take-up reinforcing bar 8.

This interconnection is desirable when, for example, another building is constructed on the revetment block group to disperse the overlaid load, but this is not related to the gist of the present invention. As described above, the revetment block 1 of the present invention has the independence and the difficulty of sinking regardless of the presence or absence of the interconnection, and the interconnection is not an essential step.

In the revetment block of the embodiment shown in FIG. 5, the suspending bar 8 is projected on the side surface of the head portion 4, and in the central portion of the revetment block, from the one-way inclined surface 5 of the head portion 4 to the frustoconical shape of the shaft leg 3. Protrusion 7
A through hole 12 is provided so as to vertically penetrate therethrough. By sequentially lowering the revetment block 1 while ejecting a pressurized water flow from the lower end opening of the through hole 12, the embankment work of the revetment block 1 can be performed accurately and efficiently even on the gently sloped surface 6 of the sand. The through hole 12 is also used as a passage for the returning water flow of the launch wave.

In the revetment block of the embodiment shown in FIG. 6, the body 2 is formed in the shape of a regular octagonal pyramid, and the head 4 and the shaft leg 3 are correspondingly formed.
Is formed in a regular octagonal columnar shape, and the shaft leg 3 has a regular octagonal pyramidal protrusion 7 at the lower end. As shown in FIG. 7, the blocks 1 and 1 are laid so that the straight side surfaces of the heads 4 and 4 are in contact with each other.

In the revetment block of the embodiment shown in FIG. 8 and FIG. 9, the one-way inclined surface of the head 4 is formed in two steps, the upper inclined portion 5a is formed with the same inclination as the lower inclined surface portion 5b. There is. The rising side surface 5c of the inclined surface portion 5a arranged toward the sea side is formed in a circular arc shape in a plan view, and has a circular or polygonal head portion 4.
Similarly to, it allows waves to escape to the left and right without resistance, which helps reduce the reflection of waves. When the diameter of the head portion 4 is large, the one-flow inclined surface 5 can be divided into a plurality of steps instead of two steps, and the rising side surface 5c can be formed in a polygonal shape instead of an arc shape.

Further, the shapes of the body 2, the shaft leg 3, and the head 4 are not limited to those shown in the drawings, and other shapes such as an ellipse, a hexagon, a quadrangle, and a pentagon can be arbitrarily adopted. Also, the body 2
If the angle θ formed by the side surface of the with respect to the horizontal plane is 45 degrees, the vertical component (f ₁ + f ₂ ) sin θ of the frictional forces f ₁ and f ₂ takes the maximum value, but the angle θ is not limited to 45 degrees. , Can be increased or decreased as appropriate.

[Advantages of the Invention] As described above, in the gentle slope revetment structure of the present invention, the revetment block 1 includes the inverted truncated cone or inverted truncated pyramidal body 2 and the cylindrical or prismatic shaft leg provided at the center of the lower end of the body 2. 3 has a circular or square head 4 of the body 2 with a one-way inclined surface 5 formed on the upper surface thereof.
The shaft leg 3 and the body 2 are embedded in the gently sloped surface 6 by vertically inserting in the vertical direction, and the single-flow sloped surface 5 of the head 4 of each revetment block 1 is arranged along the gently sloped surface 6. It is easy to obtain a good sloping revetment with a low launch height and weak wave reflection to reduce wave force. Also, due to the shape and arrangement of the revetment block 1 itself, sufficient independence and difficulty in sinking are achieved. Yes, even if the revetment block groups are not interconnected in particular, there is no uneven settlement or overturning, and a stable revetment structure can be accurately constructed on a sandy beach or the like.

Further, in the revetment structure of the present invention, between the heads 4 and 4 of the revetment blocks 1 and 1 laid so that the side surfaces of the head 2 come into contact with each other, the sand layer ground supporting the body 2 and the shaft leg 3 is communicated. An uncovered area 11 is provided, and the uncovered area 11 is filled with sand, crushed stone, etc. to provide a water-permeable filling layer, and the return water flow of waves circulates into the sea from the uncovered area 11 through the sand layer ground. In the process, the sand accompanied by the water flow is filtered out into the water-permeable filling layer, and the residual sand is deposited in the uncovered area 11 while closing the gap between the water-permeable filling layers. Is not subjected to scouring action due to the return water flow of the waves, but rather the sand that is accompanied by the return water flow reinforces the permeable filling layer, which prevents uneven settlement of the revetment block 1 and uneven inclination. It can be blocked more accurately.

Moreover, the water-permeable filling layer, which is constantly reinforced by the accompanying sand in this wave, has a lower portion that also penetrates into the lower area of the inverted truncated cone or inverted truncated pyramidal body 2 to form a divergent vertical cross section. Since it is connected and integrated with the sand layer ground on the lower side of the fuselage, the lower part of the water permeable filling layer also serves as a lower support means for resisting the vertical load of the revetment block, which causes uneven settlement of the revetment block 1 and uneven displacement. The tilt can be prevented more accurately.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an example of a revetment block used for a gentle slope revetment structure of the present invention, FIG. 2 is a vertical sectional view of the revetment structure, and FIG. FIG. 4 is a plan view of the revetment structure, and FIG. 4 is an enlarged side view of the revetment block. FIG. 5 is a perspective view showing another example of a revetment block used in the revetment structure of the present invention. FIG. 6 is a right side view showing still another example of the revetment block used in the revetment structure of the present invention,
FIG. 7 is a plan view of the revetment structure. FIG. 8 is a plan view showing still another example of the revetment block used in the revetment structure of the present invention, and FIG. 9 is a vertical sectional view of the revetment structure. 1 ... Revetment block, 1 ... Body, 3 ... Shaft leg, 4 ... Head,
5 ... One-way inclined surface, 6 ... Slowly inclined surface, 7 ... Conical protrusion, 8
… Suspended reinforcing bars, 9… Horizontal reinforcing bars for connection, 10… Vertical reinforcing bars, 11
... Uncoated area for permeation of return water stream, 12 ... Through hole for injection of pressurized water stream

Claims (1)

[Claims] 1. An inverted truncated cone or inverted truncated pyramid body 2 is provided with a cylindrical or prismatic shaft leg 3 projecting from the lower end center thereof, and a circular or prismatic head 4 of the body 2 is provided with a one-way inclined surface 5 on its upper surface. When covering the gently sloped surface 6 such as the coastline with the formed revetment block 1, the shaft leg 3 of each revetment block 1 is vertically inserted into the gently sloped surface 6 so that the shaft leg 3 and the body 2 are gently sloped 6 Heads of the revetment blocks 1, 1 which are embedded in the revetment block 1 and arranged so that the one-way inclined surfaces 5 of the heads 4 of the respective revetment blocks 1 are arranged along the gentle inclined surfaces 6 so that the side surfaces of the heads 4 come into contact with each other. Between 4 and 4,
An uncovered area 11 communicating with the sand layer ground supporting each body 2
And a sloping revetment structure in which the uncovered area 11 is filled with sand, crushed stone, or the like to provide a water-permeable filling layer.