JPH01187207A - Caisson for breakwater and revetment - Google Patents

Abstract

PURPOSE:To raise stability as well as lower the position of gravity center by a method in which stay chambers are formed inside, and upper vertical wall and a lower slant wall are formed of reinforced concrete for both faces to be exposed to waves. CONSTITUTION:In a caisson 1, reinforcing partition walls 2 are formed inside to make up stain chambers 3, vertical walls 4 are formed for the upper parts of both faces, and slant walls of a downwardly expanded width are formed for the lower part. Vertical walls 6 are also formed for both sides crossing the walls 5, and soil-charging ports 8 are formed corresponding to the chambers 3 in the upper wall 7. The ports 8 are closed with stoppers, and the caisson is towed on sea to a fixed point, where the stoppers are removed to put set water into the caisson. The caisson is settled down and filled with soil in order to set it on a rubble-mound (m). A given length of breakwater is constructed through a debris barrier between the vertical walls 6 of the adjacent caissons 1. The resistance and strength against waves can thus be increased.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a caisson for a breakwater and seawall, and is suitable for use in breakwaters and seawalls built to block ocean waves in ports, coasts, etc. used.

[Conventional technology]

Breakwaters and seawalls installed at the entrances of ports are generally constructed by installing a rubble foundation at a predetermined location on the ocean floor, and then lowering a caisson onto the foundation.

The conventional caisson used in this case is formed of reinforced concrete or the like in the shape of a rectangular parallelepiped, and has a plurality of chambers inside thereof with reinforcing partition walls. This is made with a tri-dog based on calculated design values such as tidal currents and wave forces.In order to install this caisson at the designed fixed point, the earth and sand input ports of each cavity provided in the earthen wall are tightly plugged. After blocking the blockage and towing it to the fixed point by a tugboat, etc., open the earth and sand input port and allow seawater to flow into the interior and submerge it. Then, fill the inside with earth and sand to remove the seawater, and then tow it to the fixed point on the rubble foundation. It is installed in

The caissons that are sunk in this way are installed horizontally in a line with sand control plates made of hard rubber or the like interposed between them, and adjacent caissons press against each other. A breakwater and revetment with a length of .

[Problems to be solved by the present invention]

As mentioned above, conventional caissons are filled with earth and sand, and due to their own weight they stand upright on a rubble foundation and stop receiving wave force.However, because they are formed in the shape of a rectangular parallelepiped, their height Compared to the caisson, there is less bottom wall surface that is in close contact with the rubble foundation, and the center of gravity is higher, so the overturning moment is larger.Also, the vertical sides of the caisson always oppose transverse waves, so the wave force The pressure load was high, and there was a risk of it collapsing if wave force exceeding the design value was applied.

Furthermore, when towing the caisson over the sea to the emplacement point, it is difficult to attach flotation aids such as floatation bags and flotation tanks because the four circumferential sides of the caisson are vertical. Maritime work was limited.

[Means for solving problems]

The present invention aims to solve all of the above-mentioned problems, and the caissons for breakwater seawalls according to the present invention are made of reinforced concrete or the like and have a plurality of chambers partitioned by reinforcing bulkheads inside. A caisson for a seawall is characterized in that both sides facing the waves consist of an upper vertical wall and a lower sloped wall that widens downward.

[For production]

The caisson of the present invention has a plurality of chambers by providing a reinforcing partition inside the caisson as in the conventional case, and the earth and sand inlet of each chamber is closed to make the inside hollow, and the caisson is towed at sea to the designed emplacement. After carrying it to the point, the soil input port is opened and seawater is allowed to flow into the interior to submerge it, and the interior is then filled with soil and installed at a fixed point on the rubble foundation. The multiple caissons thus submerged are constructed by interposing sand control boards made of rubber or the like between the vertical walls on both sides of adjacent caissons, and arranging the sand control boards so as to press them against each other. Build breakwaters and seawalls.

The caisson installed on the rubble foundation has its bottom wall surface widened in the direction facing the waves, which increases the contact surface with the rubble foundation and increases its stability. In addition, compared to the conventional rectangular parallelepiped-shaped caisson, the bottom part is gradually widened and earth and sand is poured into it, so the weight of the bottom part is greater than that of the top part, and the center of gravity is also shifted downward. As a result, the overturning moment is small, and the resistance strength against wave force is extremely large.

On the other hand, since the lower part of the surface facing the waves is an inclined wall, the pressure of transverse waves is reduced and supported, and even if wave force exceeding the design value is applied, it will not easily collapse, and the inclined wall Waves that exceed this amount collide with the upper vertical wall of the opposing surface and are dissipated, so the wave dissipation effect is not impaired.

〔Example〕

The drawings show one embodiment of the present invention, which will be specifically described below.

The caisson (1) according to the present invention is made of reinforced concrete or the like as in the past, and has a reinforcing partition wall (
2) to constitute a plurality of chambers (3). On both sides in the direction facing the waves, the upper part is formed into a vertical wall (4), and the lower part is formed into an inclined wall (5) that widens downward.
The cross section along the opposing direction is trapezoidal as shown in FIG. 2, and both left and right side surfaces perpendicular to this trapezoid are vertical walls (6).

In the above, the height (h) of the vertical wall (4) and the inclined wall (
The inclination angle (α) in 5) is set based on a design value calculated based on various factors such as seabed topography, tidal current, and maximum wave force. In addition, each chamber (3) is provided on the upper wall (7) of the caisson (1).
) is provided with an appropriate number of earth and sand inlets (8).

This caisson (1) is constructed by attaching a seal plug (9) to each earth and sand inlet (8) to make the inside of each chamber (3) hollow, and then towing it on the sea to the designed emplacement point. ) was removed and seawater was allowed to flow into the interior to allow it to settle down, and then earth and sand was further poured into the interior to form a rubble foundation (
m) at a fixed point.

Then, the vertical walls (
6) Sabo board formed of hard rubber etc. in between (not shown)
are arranged so that the vertical walls (6) on both the left and right sides of adjacent caissons press against the caissons, and a breakwater or seawall of a predetermined length is constructed.

In this way, the caisson (1 m) was installed on the rubble foundation (m).
), the bottom wall surface in the direction facing the waves is widened, so the surface that comes into close contact with the rubble foundation (m) increases, increasing stability.

In addition, as the bottom side is gradually widened and filled with earth and sand, the weight of the bottom side increases compared to the top side, and the center of gravity also moves downward, reducing the overturning moment and reducing the wave force. The strength of resistance to this increases dramatically. Furthermore, since the surface facing the waves is an inclined wall (5), the pressure of transverse waves is reduced and supported, and even if wave force exceeding the design value is applied, it will not easily collapse. Waves that are not dissipated by the wall (6) hit the upper vertical wall (4) and are reliably dissipated.

FIG. 4 shows another embodiment of the invention, in which a plurality of hooks (10) are symmetrically protruded near the lower part of the double-sided inclined wall (5) of the caisson (1).

In this case, when the caisson (1) is towed at sea, the flotation tank (12) is moored by hooking a wire (11) to each hook (10).

The moored flotation tank (12) provides buoyancy to the caisson (1) from both sides of the widened bottom wall.
), the stability during towing increases, and the advantage is that it can be towed safely and easily to a fixed point even if the waves are somewhat rough.

【effect〕

As described above, according to the present invention, both sides of the caisson in the direction facing the waves are composed of an upper vertical wall and a lower inclined wall that widens downward. As the caisson is more stable, the weight on the bottom side increases and the center of gravity becomes lower, increasing its resistance to wave force.In addition, the wave force applied to the caisson is attenuated by the sloping walls, making it difficult to absorb. A caisson for breakwater seawalls that can be stopped so that it will not easily collapse even if wave force exceeding the design value is applied, and that waves that are not dissipated by the sloped wall can be reliably dissipated by the vertical wall at the top. There are benefits to be gained.

[Brief explanation of the drawing]

Fig. 1 is a slope view of one embodiment of the caisson according to the present invention, Fig. 2 is a sectional view taken along line A-A in Fig. 1, Fig. 3 is a partial sectional view of the breakwater construction state, and Fig. 4 is on the sea. FIG. 5 is a cross-sectional view of the hook attachment portion during towing. DESCRIPTION OF SYMBOLS 1... Caisson, 2... Bulkhead, 3... Cavity, 4... Upper vertical wall, 5... Inclined wall, 6... Earth wall, 8... Sediment inlet,
10... Hook, 12... Levitation tank.

Claims (2)

[Claims] (1) In a breakwater caisson made of reinforced concrete or the like and having multiple chambers partitioned by reinforcing bulkheads, both sides facing the waves include an upper vertical wall and an inclined wall that widens downward. A caisson for a breakwater and seawall, characterized by comprising: (2) The caisson for a seawall according to claim 1, wherein both of the inclined walls are provided with a plurality of hooks for mooring a flotation tank, respectively.