JPS645124B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a seawall block having a wave-breaking plate and a drainage channel forming part, and a seawall using the same, and more specifically to attenuating the energy of waves hitting the coast and suppressing the power of reflected waves. This is a seawall block for constructing a permanent seawall, which prevents scouring and sucking out of the front surface of the levee body by bringing the flow of reflected waves closer to a steady flow. and a seawall using the same.

There have been many accidents in which seawalls, which have traditionally been built on sandy beaches to prevent coastal erosion, are damaged. This is due to strong reflected waves scouring the front of the embankment foundation, and strong reflected waves that flow down the concrete surface of the embankment as jets, sucking out pore water within the embankment from small gaps or cracks in the embankment, accompanied by earth and sand. It is empirically known that this is due to the so-called suction phenomenon.

Therefore, a method of covering the front wall with glue was adopted, which can withstand some amount of suction and can stand on its own and continue to function even if some soil flows out from the back. The butt wall type has a wide bottom plate to withstand scouring in front of the embankment body, and a fairly large slope of about 1:0.5. However, in this buttress-type seawall, the energy of the reflected waves is not attenuated very much, causing the beach to recede significantly, and damage and collapse accidents continue to occur due to scouring and suction of the front surface by the reflected waves.

Although all of these seawalls are made of strong concrete, the inventors believe that they do not have strong walls to protect against the waves that hit the coast with a large amount of energy, and instead attenuate the wave energy. In particular, we focused on the fact that a seawall that weakens the energy of reflected waves and allows free flow of pore water at the back of the embankment body is stronger as a result.
In Publication No. 14125, we proposed covering the embankment body with a concrete block that has a number of water storage tanks that temporarily pool the seawater that washes up with the waves and slowly releases it until the next wave.

However, as a result of further experiments, we found that even if a water storage tank is not provided, if we install a wave-breaking plate that acts as an obstacle to the breaking seawater waves, and provide a drainage channel between the wave-breaking plates, the reflected flow will reach the wave-breaking plate. The present invention was completed based on the discovery that since the water flows down through a narrow drainage channel that is dammed, it approaches a steady flow and prevents scouring of the front surface of the embankment body.

The block according to the present invention is a concrete block in which a strong bottom plate and a wave breaking plate are integrally cast. The bottom plate has a rectangular flat plate shape so that it can be stably placed on the slope surface and in close contact with each other, and may have some unevenness to stabilize the connection with each other and with the slope surface. The wave-breaking board is a sturdy board that slopes toward the bottom board to withstand wave energy.
It is preferable to provide it at one end of the bottom plate for stability of the block itself. The drainage channel should be at least as wide as possible so that there is no risk of it being blocked by organisms such as shellfish and seaweed.
It requires 70mm, preferably 100mm or more.

When such blocks are arranged so that the wave breaking plates are lined up in a straight line, a drainage channel having the same width as the drainage channel forming portion of the blocks is formed. The crashing waves consume energy as they successively pass over the wave-breaking plates from below, and when they are pulled back, they are blocked by the wave-breaking plates and flow down one after another through a narrow drainage channel. Therefore, combined with the wave-breaking effect of the wave-breaking plate, the energy of the reflected waves is significantly attenuated, becoming a gentle flow similar to a steady flow, and the wave finishes flowing before the next wave hits.
You can prepare for the next wave.

Hereinafter, the present invention will be described in detail by way of examples with reference to the drawings.

FIG. 1 is a perspective view of a bank protection block. 1 is a bottom plate; 2 is a wave breaking plate installed on the bottom plate 1; a part of the bottom 3 extends outward from the bottom plate, and forms a recess 5 with an ocean side end 4 of the bottom plate. 6 is a curved wave breaking surface, which receives waves and attenuates energy. Since the wave-breaking plate 2 is a part that receives particularly strong impact from waves, it is inclined toward the bottom plate 1 side. The wave breaking plate 2 is shorter than the bottom plate 1, and the part on the extension of the wave breaking plate on the surface of the bottom plate 1, where the wave breaking plate is not provided, is defined as a drainage channel forming part 7. 8 is the coast side end of the bottom plate 1;
9 is a water storage portion formed by the bottom plate 1 and the wave breaking plate 2.

FIG. 3 is a layout view of a seawall using the seawall blocks of the present invention, viewed perpendicular to the slope, and FIG. 4 is a sectional view taken along the line -- in FIG. During construction, the recesses 5 formed at the bottom of the bottom surface 3 of the wave breaking plate are
The coast-side end 8 of the bottom plate 1 is fitted into the bottom plate 1. The drainage channel forming portion 7 remains as it is as a missing portion of the wave breaking plate, and becomes a drainage channel 12. 10 is the slope, and 11 is the foot protection work. Waves crashing from the ocean first collide with the breaking wave surface 6a and break mechanically, and some of the seawater flows into the water storage area 9a.
stored inside. The remaining seawater further collides with the wave breaking surface 6b of the upper block and breaks, and a portion is stored in the water storage section 9b. In this way, as the seawater sequentially exceeds the breaking wave surfaces 6c and 6d and rises to the upper water storage portions 9c and 9d, the amount of seawater decreases significantly and the wave energy also attenuates. When the waves recede, the seawater stored in the water storage section 9 is blocked by the wave breaking plate 2, passes through the drainage channel 12 which is the narrow part, and enters the lower water storage section 9.
It further flows down through the lower drainage channel 12. In this way, the reflected waves cannot flow down all at once, so
The flow is attenuated and becomes close to a steady flow, so there is no scouring of the front of the embankment, and there is no suction from the back of the embankment. Even if it were to be sucked out, the bank wall covered slope according to the present invention would not lead to the destruction of the embankment body, which has the flexibility to transform into a slightly depressed slope. In this embodiment, when the revetment blocks were arranged on the slope, the upper and lower stages were staggered, but they do not necessarily need to be staggered, and the drainage channels may run directly.

FIG. 2 is a perspective view of another embodiment of a seawall block. A wave breaking surface 6 is formed by combining planes, and one end of the wave breaking plate 2 is made to protrude from the bottom plate 1. Therefore, a wide flat surface remains on the bottom plate at the other end of the wave-breaking plate 2, but only the remaining part will overlap during construction and the protruding part of the wave-breaking plate of the adjacent bank protection block will overlap. This corresponds to the drainage channel forming part 7.

The flow velocity of the reflected flow passing through the drainage channel 12 increases only in this part, and there is a risk that a suction phenomenon may occur at the contact surface between the bottom plates. 12, the suction phenomenon can be completely prevented.

Furthermore, the wave breaking plate 2 may be divided into two parts, and the drainage channel forming part 7 may be provided in the middle part, or the wave breaking plate 2 may be provided in the center part of the bottom plate 1.

As described above, according to the present invention, the amount of seawater and the energy of waves rising up the embankment body are drastically reduced by the water storage part and the wave breaking plate of the revetment block that covers the slope, and the energy of the reflected waves is not only small.
The flow is close to a steady flow, and a permanent seawall with no fear of scouring the front surface of the embankment body can be obtained.

[Brief explanation of the drawing]

The drawings show embodiments of the invention, FIGS. 1 and 2.
The figure is a perspective view of the revetment blocks, Figure 3 is a layout of the revetment blocks viewed from the vertical direction of the slope, and Figure 4 is a perspective view of the revetment blocks.
The figure is a sectional view taken along the line -- in FIG. In the drawing, 1 is the bottom plate, 2 is the wave breaking plate, 4 is the ocean side end, 5 is the recess, 6 is the wave breaking surface, 7 is the wall plate drainage channel forming part, 8 is the coast side end, 9 is the water storage part, 10 is the slope,
11 is a foot protection work, and 12 is a drainage canal.

Claims (1)

[Scope of Claims] 1. A block for a seawall, in which a rectangular flat bottom plate and a wave-breaking plate installed at an angle toward the bottom plate, leaving a drainage channel forming part on the bottom plate, are integrally cast. 2. A large number of revetment blocks, each of which is integrally cast with a flat bottom plate and a wave-breaking plate installed at an angle to the bottom plate, leaving a drainage channel forming part on the bottom plate, are placed against the bottom plate of the wave-breaking plate. A seawall is constructed by placing the bottom plate in close contact with the slope so that the obtuse-angled side faces the ocean and the wave-breaking plates are lined up in a straight line.