JPH0119481B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention covers the entire slope of a sea wall with concrete in the form of a slope or steps, and drains water from the concrete surface almost parallel to the coastline and intermittently. This invention relates to a method for constructing a permanent seawall that prevents scouring and suction phenomena in front of the seawall by planting the seawater leaving a channel so that the reflected flow of the seawater that washes up against the seawall approaches a steady flow.

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.

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.
Publication No. 14125, Japanese Patent Publication No. 14126, Publication No. 14125, Japanese Patent Publication No. 1983-14126, Japanese Patent Application Publication No. 1983
- In JP-A No. 168805 and JP-A-60-168806, a concrete block with a water storage section is placed in front to temporarily pool the seawater that washes up with the waves and slowly release it until the next wave. We proposed a seawall that has a reflective flow control function by covering the dam body with a large number of these concrete blocks.

The present invention provides a method for constructing a seawall having a reflected flow control function by directly placing concrete on a slope without placing such concrete blocks in advance.

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

Figure 1 is a perspective view of a wave-breaking plate that is placed on a slope before concrete is placed on a seawall.
1 is the wave-breaking surface of the wave-breaking plate 11, and waves collide directly with this portion. 2 is a water storage surface of the wave-breaking plate 11, which dams up reflected waves and brings the reflected flow closer to a steady flow. Reference numeral 3 denotes a side wall provided at one end of the wave breaking plate, which stabilizes the wave breaking plate 11 and further enhances the reflected flow adjustment function. The side wall 3 extends from the water storage surface 2 and has a shape that gradually becomes lower, and is cut vertically at the tip, and this cut portion is used as the concrete buried surface 4. Nothing is provided at the other end of the wave breaking plate.

In Figure 2, the wave-breaking surfaces of the wave-breaking plates shown in Figure 1 are directed toward the ocean, and after arranging the wave-breaking plates while maintaining a gap in the drainage channel 5 between the wave-breaking plates, concrete is poured to the thickness of the concrete buried surface 4. This is a layout diagram of the seawall obtained by pouring the seawall, seen from a direction perpendicular to the slope. FIG. 3 is a sectional view taken along the line -- in FIG. 2. Drainage channels are shellfish;
The width is at least 70 mm, preferably 100 to 200 mm, without the risk of being blocked by organisms such as seaweeds.
In some cases, more than this is required. 6 is the concrete pouring surface, 7 is the slope surface, and 8 is the foot protection work. 9
is a water storage portion formed by the side wall 3 and the wave breaking plate. As shown by the arrow in Figure 3, the waves crashing from the ocean crash into the lowest wave breaking plate, go over the breaking surface 1 and fill the water storage part 9, and then go over the next level wave breaking plate and fill the water storage part 9. In this way, the waves collide with the breaking wave surface 1 one after another, consuming energy, filling the water storage section 9 with seawater, and reducing the amount of seawater.

When the waves recede, if it is a normal seawall, the water will turn into a jet and flow down rapidly, but in the case of the seawall of the present invention, as shown by the arrow in FIG. Since the reflected flow passes through the channel 5 and flows down, it approximates a steady flow and can prevent scouring of the front surface of the embankment body.

According to the construction method of the present invention, it can be easily constructed by simply arranging wave-breaking plates and pouring concrete.

FIG. 4 is a layout diagram of a seawall constructed according to another embodiment as seen from a direction perpendicular to the slope, and FIG. 5 is a sectional view taken along the line -- in FIG. 4. In the case of this embodiment, a wave breaking plate 11 which is cut at a portion indicated by a two-dot chain line in FIG. 1, that is, a wave breaking plate 11 without side walls 3 is used. This embodiment is the same as the previous embodiment except that the side wall 3 is not provided, and although the water storage effect is somewhat inferior, the construction is simpler, and this embodiment is preferable depending on the coastal conditions.

In the above embodiment, the wave breaking plates are arranged in parallel,
Although the drainage channel is placed between the drainage channel of the next stage and the drainage channel, it is not necessarily necessary to shift the drainage channel in this way, and the drainage channel may run directly. Furthermore, the wave-breaking plate 11 can be placed at the same time when concrete is placed on the slope without placing the wave-breaking plate in advance.

As described above, by the method of the present invention in which concrete is placed directly on the slope of the embankment body, the energy of wave seawater is temporarily stored, and the flow of reflected waves is adjusted to avoid a jet flow and approximate a steady flow. , it is possible to prevent scouring of the embankment body foundation and construct a stable seawall for a long period of time using a simple method.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a perspective view of a wave-breaking plate when it is placed in front, FIGS. 3 is a cross-sectional view taken along the line -- in FIG. 2, and FIG. 5 is a cross-sectional view taken along the line -- in FIG. In the drawing, 1 is the wave breaking surface, 2 is the water storage surface, 3 is the side wall, 4 is the concrete buried surface, 5 is the drainage channel, 6
7 is the concrete pouring surface, 7 is the slope surface, 8 is the foot protection work, 9 is the water storage area, and 11 is the wave breaking plate.

Claims (1)

[Claims] 1 A plurality of sturdy wave-breaking plates are arranged approximately parallel to the shoreline with the wave-breaking surfaces facing the ocean side, maintaining the interval between each other to form a drainage channel, and multiple rows of the wave-breaking plates are provided in order to prevent damage to the slope. A method for constructing a reflected flow control type seawall, which is characterized by pouring concrete and curing the wave-breaking plate and concrete together.