JP3405605B2 - Sea area control method using submerged piles - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a sea area using submerged piles for preventing coastal erosion due to waves.

[0002]

2. Description of the Related Art Conventionally, coastal levees have been used as coastal conservation structures (wave control structures) for preventing coastal erosion.
Coastal jetties and seawalls have been built. However, each of these coastal structures is provided so as to project from the sea surface, and therefore there is a problem that the landscape is impaired. Especially in the national park areas and beach parks, the landscape is an important planning factor, so these coastal structures cannot be easily selected.

Therefore, in recent years, as a wave control structure, a submerged sea area control structure has attracted attention because it has the advantages that the landscape is not damaged and the water quality is kept clean by seawater exchange due to wave overtopping. ing. Conventionally, submerged sea area control structures include a submerged dike built on the seabed and having a trapezoidal cross section, and a three-dimensional block stacked on the seabed, such as a tetrapod (trademark).

[0004]

However, in the case of the submersible sea area control structure, the structure itself sinks due to its own weight and is buried in the sand, and is gradually buried in the sand for several years. Several decades later, problems such as almost no use as a wave control structure have occurred. In addition, in the case of these structures, the wave-dissipating effect cannot be expected unless they have a certain long width in the direction offshore.
As a result, there is a problem that the area to be constructed increases and the construction cost also becomes enormous. Of course, the construction period is also long.

On the other hand, considering that the top height of these submerged sea area control structures is fixed and the height difference due to the tide is close to 1 m, the wave control effect due to the tide difference varies with time, There is also a problem that the wave control effect can hardly be expected depending on the time of day.

Therefore, the main problems of the present invention are that the function as a wave control structure can be maintained almost permanently, the construction cost is low, and the wave and beach deformation control effect is always constant regardless of the time zone. It is to provide a sea area control method using submerged piles that can be expected by

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a pile for driving a pile into the seabed at a distance from each other in a state where the pile head is submerged below the sea surface without protruding above the sea. It is characterized in that the piles are arranged in a row and project from the seabed, and the tops are connected to each other by sand retaining members having a height not higher than the pile head to construct a self-supporting structure.

In the present invention, when the pile array is a single row, the opening area ratio ε (ε = A / (, where S is the pile core interval, h is the water depth, and A is the opening area per pile interval). S × h))
Is 0.1 to 0.2.

In this case, a gap is provided between the piles,
It is also possible to provide a plate member for sand blocking below the top height of the pile head between the piles, and instead of the plate member for sand blocking, it is provided so as to project laterally from the pile. The joint member between the piles may be used as a sand stopper. Moreover,
It is also possible to provide the plate member for sand blocking and the joint member between the piles only on the upper and lower portions in the longitudinal direction of the pile and open the intermediate portion.

Further, the pile arrangement may be a double row, especially a double row in the coastal direction. In this case, the opening area ratio ε (ε = A / (S × h)) of each column is 0.2 to 0.
It is set to 4. 1/4 of the dominant wavelength obtained from the wavelength-frequency characteristics based on the observation of the target local wave.
It is desirable to be 3/4. Further, adjacent shore-side piles and offshore-side piles can be connected to each other by the sand retaining plate member.

[0011]

In the present invention, the piles are arranged in a row under the surface of the sea without being projected to the sea. Therefore,
The scenery will not be impaired, and the waves that flow over the piles will allow a suitable exchange of seawater to keep it clean. Further, since the structure is formed by arranging piles, the function as a wave control structure can be maintained almost permanently without being buried in the sand. Moreover, the construction cost is low and the construction period is short. Further, by providing the sand retaining member, it is possible to prevent the sand from flowing out toward the shore offshore behind it, and a beach deformation control effect can be expected.

In this case, the piles can be arranged with almost no space between them, but a space is provided between the piles and a sand stopper plate or a joint member instead of the sand stopper plate is used as a sand stopper member to reduce the construction cost. It is also cheap and can prevent the movement of sand. Further, by providing the sand retaining members only on the upper and lower portions of the pile in the longitudinal direction and opening the middle portion, it is possible to reduce the material cost, facilitate the movement of fish and shellfish, and destroy the ecosystem. Absent.

Further, the pile row may be double row in the coastal direction. In this case, the adjacent shore-side piles and the offshore-side piles are connected to each other by a sand-blocking plate-like member so It also has a wave-dissipating effect on waves other than the direction.

On the other hand, even if there is a difference in tide level, the opening area ratio can be maintained within a certain range by varying the pile head top height of the piles arranged in a row or by providing the moving pipe, Alternatively, it can be held at a substantially constant value.

[0015]

EXAMPLES The present invention will be described in detail below based on examples.
FIG. 1 is a perspective view of a wave control structure according to the present invention in a single-row arrangement. Wave control structure by the pile according to the present invention, for example, in a sandy beach with large waves, the wave height and its flow are made calm to make a sea area suitable for sea bathing, or a sea area suitable for aquaculture of seafood. In addition, piles 1, 1, ... Are preferably arranged side by side in the normal direction to the direction of the rushing waves on coasts where there is a risk of storm surge due to high wave areas and typhoons. The piles 1, 1, ... Are provided in a state in which the pile heads are submerged below the sea surface without protruding above the sea in order to exchange the sea water for cleaning the water quality while considering the landscape. Pile driving is usually carried out by driving into the seabed with a pile driving ship. Therefore, steel pipe piles that can be driven and are inexpensive are most preferable as pile types. However, it does not exclude other pile types, such as concrete prefabricated piles. Also, piles 1, 1, ...
Can be arranged in a row in a dense state without any gap therebetween, but this is uneconomical. Therefore, the sand blocking members 2, 2, ... Are arranged between the piles 1 with a certain gap. The height of the sand retaining member 2 is preferably 1/2 or more of the protruding length of the pile. According to the experiments conducted by the present inventors, which will be described later, the height of the sand stopper member 2 is 1 / the protrusion length of the pile.
When it exceeds 2, the outflow of sand is almost eliminated, and the beach deformation control effect is remarkably high.

Various structures are conceivable as the structure of the pile 1 and the sand blocking member 2.
First, as shown in FIG. 2, locking portions 1a and 1b, which are constituted by a pair of locking pieces having an L-shaped cross section, are provided along both sides of the pile 1 in the longitudinal direction, and both sides are engaged with each other. The plate-like sand stop plate 2A to be dropped is installed. in this case,
It is important to perform sufficient strength design so that the sand stop plate 2A does not buckle due to the collision energy of waves.
For example, as shown in the drawing, it is necessary to devise a hollow plate with sufficient reinforcing material, or to form the hollow portion into two layers.

Next, the example shown in FIG. 3 is an example in which a pile is a square steel pipe 3 and a sand stop plate 2A having a hollow structure is arranged between the square steel pipes 3, 3 ... As in the case of FIG. 2, the locking structure in this case has locking portions 3a, 3a formed by a pair of locking pieces having an L-shaped cross section along both sides in the longitudinal direction of the pile 3.
b are provided respectively, and the plate-like sand stop plates 2A engaging with both sides are dropped and installed.

Further, the examples shown in FIGS. 4 to 6 are examples in which the joints fixed by welding or the like on both sides in the longitudinal direction of the steel pipe piles 1, 1 ... Is a joint structure in which the pipes 2a and 2b are bitten in a ring shape,
5 shows a joint structure including a pair of L-shaped joints 2b and T-shaped joints 2a, and FIG. 6 shows a joint structure including pipes 2a and T-shaped joints 2b.

In the present invention, in the case of a single row pile, as shown in FIG. 7, the pile core interval is S, the water depth is h,
Assuming that the opening area per pile interval is A, the opening area ratio ε (ε
= A / (S × h)) is preferably in the range of 0.1 to 0.2. The reason for this will be described in detail in an experimental example to be described later, and when the opening area ratio ε is less than 0.1, it is uneconomical, and the corresponding effect cannot be expected, resulting in a large energy loss. Also, 0.2
When it exceeds, the transmissibility becomes large and the wave-dissipating effect becomes small. The sand stopping member 2 may be continuously provided from the seabed to its top, or may be provided only in the upper and lower portions in the depth direction and the middle portion may be opened. The wave-dissipating effect is almost determined by the open area ratio on the sea surface side, so even if the middle part is open, it does not have a bad effect, and in order to prevent the movement of sand, it has a certain height above the seabed. Is sufficient, and there is no problem even if the middle is opened.

On the other hand, it is difficult to maintain the opening area ratio ε at a constant value in the above-mentioned structural example because the sea level rises and falls by nearly 1 m due to the ebb and flow of the tide. It is possible to keep it at or almost constant value. First, the example of FIG. 8 is an example in which the piles are arranged in a row without a gap therebetween and the pile head top height of the piles is changed. Three types of piles 4A with different pile lengths,
4B and 4C are prepared and arranged in order. The sea level is HWL (High Water Level) and LWL (Lo
w Water Level), the opening area ratio ε is 0
It is possible to avoid such a situation, and it is possible to change the opening area ratio ε within a predetermined range.

Further, in the example shown in FIG. 9, the pile head top height of the piles 1, 1, ... Is raised or lowered according to the vertical movement of the sea surface,
This is an example in which the aperture area ratio ε is kept substantially constant. The pile heads of the piles 1, 1, ... Lined up are covered with moving pipes 5, 5, ... Having a diameter slightly larger than the upper end, and connected to the upper ends of the moving pipes 5, 5 ,. The buoy 7 is attached, and the moving pipe 5 is suspended in the sea by the buoy 7 floating on the sea surface.
Since the pile 1 moves up and down using the pile 1 as a guide member and the relative position from the sea surface does not change, the opening area ratio ε can be kept substantially constant. At the joint between the pile 1 and the moving pipe 5, a stopper 1a is provided on the pile 1 side and a stopper 5a is also provided on the moving pipe 5 side, and these interfere with each other and the moving pipe 5 comes out of the pile 1. Are prevented.

Next, the arrangement of the piles arranged in line is as shown in FIG.
As shown in 0, it is also possible to have a double row arrangement in the coastal direction. For example, in the case of the two-row arrangement shown in the figure, the synthetic aperture ratio ε _C obtained by synthesizing the aperture area ratios ε ₁ and ε ₂ of each column is ε
It is represented by _C = ε ₁ × ε ₂ / (ε ₁ + ε ₂ ). If the opening area ratios ε ₁ and ε ₂ in each row are the same, then ε _C = ε / 2, where ε _C is equal to 0.
When 1 to 0.2 is set, ε can take a value of 0.2 to 0.4.

Further, as the shore-offward distance P between the pile rows,
It is arranged as 1/4 to 3/4 of the dominant wavelength obtained from the wavelength-frequency characteristics based on the observation of the target local wave. In the case of the double row arrangement, when a part of the overtopping waves that have passed over the offshore pile row collides with the shore side pile row, it is reflected offshore as a reflected wave. The reflected wave and the overtopping wave that has passed over the pile row on the offshore side interfere with each other, so that a wave suppressing effect can be expected. In this case, under the condition that the installation range of the structure is not expanded so much, it is desirable to arrange the structure at about 1/4 of the dominant wavelength. However, in reality, depending on the weather conditions,
Since the dominant wavelengths are different, the pile interval P is comprehensively determined in consideration of these. Further, in the case of the double row arrangement, as shown in FIG. 11, the piles adjacent to each other in the offshore direction can be connected by the sand stop members 10 and 10 as an aligned arrangement, or as shown in FIG. Further, the shore-side piles and the offshore-side piles may be arranged in a staggered manner, and the adjacent shore-side piles and the offshore-side piles may be connected to each other by the sand retaining members 10, 10 ... The double row pile may be simply a double row pile, which is a single wave-dissipating structure, apart from the shore-offward distance of the piles determined from the dominant wavelength.

By the way, according to the trial calculation of the rooting length of the submerged pile, the condition of the design wave is converted into the offshore wave height H ₀ '= 4.25 m,
The offshore wave period T ₀ = 11 seconds, the condition of the pile is the projecting length 7.74m, diameter
When the length is 1.8 m, the thickness is 25 mm, and the pitch is 2.05 m, the rooting length is 16.57 m and the required steel pipe length is about 25 m. Also, if the pile conditions are a projected length of 7.74 m, a diameter of 1.5 m, a thickness of 25 mm and a pitch of 1.75 m, the rooting length is 15.08 m,
The required steel pipe length is about 23 m. In any case, it is necessary to have a rooting length that is more than twice the protruding length (the length from the seabed to the pile head) for self-reliance.

The effects of the present invention will be further clarified below by experiments. [Experiment of Wave Control Effect] A two-dimensional wave-making water tank equipped with a 74 m long, 1 m wide, 1.8 m high wave-reflective absorption type wave making device was used, the model floor was a horizontal floor, and about 48 m from the wave making plate. A step type cross-section model with a slope of 1/20 was installed separately, and a steel pipe pile row model was installed at a uniform water depth h = 28 cm (MWL: Middle Water Level) 10 m away from this. The offshore wave depth was 70 cm. The scale of the model is 1 depending on the specifications of the representative wave and the wave-making ability.
/ 25, the steel pipe piles and sand stop plates are installed in a single row or double rows (two rows) as shown in FIG. 1 or 10, and the height hr from the pile head to the water surface, the pile row interval P, the sand The stop plate height hp was used as a parameter. Detailed model specifications are shown in Table 1. Further, regular waves were used as the experimental waves, and the waves that are erosive when classified by the C parameter indicating the beach deformation type were set as shown in Table 2. Also, to measure the incident wave height, three wave height meters were installed at the point 4.0 m away from the offshore side steel pile pile core for reflection and reflection separation. Three wave height meters were installed at a point 2.0 m away from. The wave transmissivity K _t and the reflectivity K _r were calculated as energy ratios.

[0026]

[Table 1]

[0027]

[Table 2]

(1) Wave control effect in single row arrangement FIG. 13 shows the opening area ratio ε when the steel pipe piles are arranged in a single row.
The relationship between the wave transmissivity K _t and the reflectance K _r is arranged by the offshore wave period T. The experiment was performed with several kinds of wave heights in each cycle, but since there was no significant difference in K _t and K _r , the average value was used as the representative value of each cycle. From FIG. 13, it was found that K _t and K _r do not show much period dependence and can be expressed as a function of ε. In application to an actual design, the wave transmissibility K _t is first determined. For example, this wave transmissivity K _t is 0.
6 is set. Once the wave transmissivity K _t is determined, the opening area ratio ε corresponding to it is determined, and the pile length, the pile interval, and the height of the sand stop plate are arbitrarily set so that the opening area ratio ε is equal to or less than this. It will be decided. When the wave transmissivity K _t = 0.6, the aperture area ratio ε is 0.12.

Further, the submerged pile row combined with the sand stop plate according to the present invention is a structure mainly for reducing the transmitted wave by reflection, but jet mixing between the steel pipe piles, the steel pipe pile head and the sand stop plate are performed. Since the energy of the wave is dissipated by the vortex and its separation at the end, the energy dissipation rate Eε is Eε = 1-K _t
^When obtained and evaluated as ^2- K _r ² , the results shown in FIG. 14 are obtained. From FIG. 14, the energy dissipation rate Eε is ε
It can be seen that the angle becomes a mountain-shaped curve showing a peak in the vicinity of 0.1 to 0.2. This is because the size of the vortex generated is ε = 0.1
It is considered that this is because the depth becomes maximum at the nearby water depth.

(2) Wave control effect in double row arrangement FIG. 15 shows the pile row interval P when the steel tube pile rows are two in the horizontal axis.
K _t and the ratio P / L between the wavelength L in the pile column installation depth, the vertical axis
And K _r are taken to show their relationship.
The experiment is h _r = 3.8 cm, h _P = h _K = 24.2 cm both on the shore and offshore.
(Ε = 0.136 in this case), and there was no significant difference due to the wave height as in the case of the single row arrangement, so K _t for each P / L
And the average value of K _r . From FIG. 15, K _t is P
It becomes 0.50 or less when /L>0.20, and as a whole, it is known that the wave control effect is relatively effective in the range of P / L = 1/4 to P / L = 3/4. Also, K
_r shows a peak value because the influence of resonance becomes stronger near P / L = 1/2, and conversely, the influence of resonance weakens before and after K _r.
Tended to become smaller.

From the above results, the effect of the resonance phenomenon between the steel pipe pile rows appears more clearly on K _r than K _t , and the pile row spacing is 1/4 of the wavelength as seen from the experimental results.
It has been found that the wave control effect is enhanced when it corresponds to ~ 3/4. In actual application, the dominant wavelengths of waves differ depending on whether they are calm or high waves.
It is preferable to obtain the 3/4 value, and to adopt the length of the range where these values overlap each other as the pile interval P. Specifically, FIG.
As shown in 6, when the dominant wavelength in quiet time is 10 m and the dominant wavelength in wave is 20 m, the length is 1/4 to 3/4 of each dominant wavelength L, and A range in which the numerical values overlap, that is, 5 to 7.5 m is a suitable pile installation interval.

[Experiment of beach deformation control effect] A two-dimensional wave-making water tank equipped with a reflection-absorption type wave-making device having a length of 74 m, a width of 1 m, and a height of 1.8 m was used, and the offshore wave-making depth was 60
cm, 1/30 from the position 49.8 m away from the corrugated plate
A fixed mortar fixed bed was prepared, and a moving bed having a thickness of 15 cm was installed on it. The scale of the model is 1/25 depending on the specifications of the representative wave and the wave-making ability, and the water depth h = 28 cm installed on the slope.
The pile diameter D = 4.8 cm and the pile protrusion length h _K = 24.
The steel pipe piles and sand stop plates were arranged in a single row or a double row so that the pile pile core spacing S was 9.6 cm. Other parameters were the sand stop plate height h _P and the pile row interval P. Regular waves and irregular waves were used as experimental waves, and the specifications were set as shown in Table 3. A contacting sand gage was used to measure the beach deformation. The beach change after 32 hours of action was measured. As the bottom material, coal ash granulated sand was used.

[0033]

[Table 3]

(1) Beach Deformation Control Effect in Single Row Arrangement FIGS. 17 and 18 show that in the single row arrangement, the sand stop plate height h _P is 0/4 h _K , 1/4 h with respect to the pile protrusion length h _{K. K} , 2 /
Sediment transport in the case of changing the 4h _K, 3 / 4h _K and shows the changes in shoreline position. The amount of drift sand is the sum of the amount of movement of sand on the shore side of the steel pipe pile from the shoreline to the installation position of the steel pipe pile. Positive indicates the inflow (deposition) of sand from the steel pipe pile to the shore side.
Negative means outflow of sand (erosion). The experimental wave used was erosion type W1.

According to FIGS. 17 and 18, the amount of drift sand decreased as the sand stop plate became higher,
When it exceeds 2/4 h _K , almost no runoff of sand occurs. At the same time, due to the wave attenuation effect, the change of the shoreline position becomes sharply small, and the beach deformation control effect becomes large. On the other hand, when the sand stop plate height h _P is small, there is a phenomenon that the shoreline position recedes from before the steel pipe was installed.

(2) Beach deformation control effect in double row arrangement FIGS. 19 and 20 show the amount of drift sand and the shoreline position for pile waves of 40 cm and 120 cm for each wave of the experimental waves W1, W2 and W3. It shows the change of.
It should be noted that the amount of drift sand is the total amount of sand movement at the shore side steel pipe pile installation position, and h _P was judged to be effective in a single row arrangement 2
/ 4 h _K. Further, K _t in this case is about 0.65.

From FIGS. 19 and 20, the outflow of sand can be prevented by installing a steel pipe pile row, and the effect is not significantly affected by the pile row spacing P, and the erosion tendency tends to increase as the working wave period becomes longer. It turned out to be big. Also,
The beach section was a kind of step topography where the sand was deposited near h _P and the height on the shore side did not change much. Sand slipped into the step terrain near the shoreline and was eroded, and the shoreline position also receded, but it was found to be slightly improved compared to before the installation.

Next, FIGS. 21 and 22 show the relationship between the amount of drift sand and the shoreline position when W3 is used as the experimental wave and the sand stop plate h _{P is set} to 2/4 h _K and 3/4 h _K. is there. From the figure, it is clear that K _t is about 0.53 when h _P is 3/4 h _K, and the wave control effect is large, so the beach deformation control effect is proportionally larger. . Incidentally, the tendency of the beach section showed the same tendency as the experimental result shown in FIGS. 19 and 20.

Further, in order to examine the effect on the long-period wave component, an experiment was conducted using an irregular wave having a relatively significant wave period. FIG. 23 shows a regular wave W3 having a period of 2.4 s.
And the shape of the beach cross section and the change of the accumulated sand load when the irregular wave W4 having a significant wave period of 3.2 s is applied. In the case of W4, the erosion near the shoreline was large, but the outflow of sand was stopped by the effect of the plate, and the shore side of the steel pipe pile was almost horizontal, and sand was deposited between the steel pipe pile rows. On the other hand, the amount of drift sand is almost equal to W3,
It was also found to be effective for long-period wave components.

From the above (1) and (2), the beach deformation control effect can be summarized as follows: By securing a sand stop plate to some extent, it is possible to prevent the outflow of sand off the shore, and to sufficiently control the beach deformation. It is thought that the effect can be expected.

[0041]

As described above in detail, according to the present invention, since the waves are controlled by arranging the piles, the function as the wave control structure can be maintained almost permanently. Further, by providing the sand retaining member, it is possible to prevent the sand from flowing out toward the shore offshore behind it, and a beach deformation control effect can be expected. On the other hand, since it is driven by piles, the construction cost is lower than that of the conventional construction method. Furthermore, by installing a moving pipe and making the pile head height variable according to the sea level, a constant wave control effect can be expected at all times.

[Brief description of drawings]

FIG. 1 is a schematic perspective view of a wave control structure using a single row pile according to the present invention.

FIG. 2 is a horizontal cross-sectional view showing a structural example of a pile and a sand retaining member.

FIG. 3 is a horizontal cross-sectional view showing another structural example of the pile and the sand retaining member.

FIG. 4 is a horizontal cross-sectional view showing another structural example of the pile and the sand retaining member.

FIG. 5 is a horizontal cross-sectional view showing another structural example of the pile and the sand retaining member.

FIG. 6 is a horizontal sectional view showing another structural example of the pile and the sand retaining member.

FIG. 7 is a front view for explaining the definition of the opening area ratio.

FIG. 8 is a front view showing another pile in a row.

FIG. 9 is a vertical cross-sectional view when a moving pipe is provided on the pile head.

FIG. 10 is a schematic perspective view of a wave control structure having a double row arrangement according to the present invention.

FIG. 11 is a plan view showing a double row double row arrangement in which piles are connected in the offshore direction.

FIG. 12 is a plan view showing a staggered double-row arrangement in which adjacent shore-side piles and offshore-side piles are connected.

FIG. 13: Opening area ratio ε and transmissivity K _t in the case of a single row pile,
It is a relationship diagram with reflectance K _r .

FIG. 14 is a diagram showing the relationship between the opening area ratio ε and the energy dissipation rate Eε in the case of a single row pile.

FIG. 15 is a relational diagram of pile row spacing / wavelength (P / L), transmissivity K _t , and reflectance K _{r in} the case of a double row pile.

FIG. 16 is a diagram for explaining a method of determining a shore-offshore pile interval.

FIG. 17 is a diagram showing the relationship between the height of the sand stopper plate and the amount of drift sand in a single-row arrangement.

FIG. 18 is a diagram showing the relationship between the height of the sand stopper plate and the shoreline position in a single-row arrangement.

FIG. 19 is a relationship diagram between the working wave period and the amount of drift sand in a double row arrangement.

FIG. 20 is a relationship diagram between the working wave period and the shoreline position in the double row arrangement.

FIG. 21 is a diagram showing the relationship between the height of a sand stopper plate and the amount of drift sand in a double-row arrangement.

FIG. 22 is a diagram showing the relationship between the height of the sand stopper plate and the shoreline position in the double-row arrangement.

FIG. 23 is a diagram showing a beach cross-sectional shape and a cumulative sand load in the case of a long-period wave component.

[Explanation of symbols]

1.3.4A-4C ... Pile, 2 ... Sand stopper member, 2A ... Sand stopper plate, 2B-2D ... Joint and sand stopper member, 5 ... Moving pipe, 6 ... Chain, 7 ... Buoy

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroaki Okuda 1 Higashishinmachi, Higashi-ku, Nagoya, Chubu Electric Power Company (72) Inventor Masayoshi Okamoto 1 Higashi-shinmachi, Nagoya, Chubu Electric Power Company (72) ) Inventor Takamichi Niwa 3-21-25 Marunouchi, Naka-ku, Nagoya City Sato Engineering Co., Ltd., Nagoya Branch (72) Inventor Noriyoshi Kaneko 4-12-20 Nihonbashimotocho, Chuo-ku, Tokyo Sato Industry Co., Ltd. (72) ) Inventor Noriyuki Utagawa 4-12-20 Nihonbashihonmachi, Chuo-ku, Tokyo Sato Kogyo Co., Ltd. (56) Reference JP-A-2-58614 (JP, A) JP-A-6-17430 (JP, A) Special Kaihei 1-102112 (JP, A) Actual Kaihei 5-38030 (JP, U) Actual Kaihei 2-70018 (JP, U) Actual Kaihei 2-93334 (JP, U) (58) Fields investigated ( Int.Cl. ⁷ , DB name) E02B 3/06 3 01

Claims (6)

(57) [Claims] 1. A pile of driven piles is installed on the sea floor at a distance from each other with the pile head submerged below the surface of the sea without protruding above the sea. The piles are connected by the following sand retaining members to build a self-supporting structure. The pile arrangement is based on a single row, the pile core spacing is S, the water depth is h, and the pile heads and Assuming that the opening area per pile interval formed by the top end of the sand retaining member is A, the opening area ratio ε (ε =
A / (S × h)) is set to 0.1 to 0.2. A method for controlling a sea area by a submerged pile. 2. The sea area control method using a pile according to claim 1, wherein the sand retaining member is a plate-like member, and is installed by being dropped between locking portions formed on opposite sides of the pile. 3. The sea area control method using a submerged pile according to claim 1, wherein a joint member between the piles, which is provided so as to project laterally from the pile, is used as a sand retaining member. 4. The pile heads are arranged below the sea surface without being protruded into the sea and the piles are driven into the bottom of the sea at a distance from each other. The piles are connected to each other by the following sand retaining members to build a self-supporting structure. The piles are arranged in two rows in the coastal direction. In each single row, the pile core spacing is S, the water depth is h, and the piles are An opening area ratio ε (ε = A / (S × h)) is 0.2 to 0, where A is the opening area per pile interval formed by the pile head and the top end of the sand retaining member between the cores. A sea area control method using submerged piles, characterized in that 5. The sea area control method using submerged piles according to claim 4, wherein adjacent shore-side piles and offshore-side piles are mutually connected by the sand retaining member. 6. The arrangement interval of pile rows is 1/4 of the dominant wavelength obtained from the wavelength-frequency characteristics based on the observation of the target local wave.
The water area control method using the submerged pile according to claim 4, wherein