JPH01318613A - Marine structure on softly arranged bottom - Google Patents

Abstract

PURPOSE:To reduce the influence of a wave and reduce grounding pressure and reduce the influence of earthquake and interrupt no seawater exchange by providing a floating body foundation section with internal and external double transmission type wave dissipation body having a retarding basin section and an opening. CONSTITUTION:Transmission type internal-and-external-double-wave-dissipation structural-bodies 5, 6 with slots 4 bored respectively through, on the periphery of a floating body foundation section 1 set on a mound 3 set on a foundation 2 are erected integrally with the foundation section 1 so that retarding basin sections 7 may be placed between the bodies 5, 6. The lower section of the external side wave dissipation structural-body 6 is provided with an opening section 8 for fluid outflow and inflow, communicating with the retarding basin sections 7 and opening to external sea. By an internal structural body 10 erected on the central section of the internal and external wave dissipation structural bodies 5, 6 and the floating body foundation section 1, a deck section 11 is supported, and on the deck section 11, mounted facilities 12 are arranged.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is applicable to marine recreation facilities, residential facilities, marine resort facilities, facilities with research and development functions such as fisheries, seabed resource development, marine engineering, etc., and facilities with fisheries functions. This relates to offshore structures.

(Prior technology) There are two methods for locating offshore facilities: the floating method, in which the facilities are moored to the seabed via tight members and floating on the sea surface, and the Tsukishima method, in which an island is constructed in the ocean and facilities are installed on the island. There are two main types: the bottom-mounting method, in which the floating foundation is placed directly on the bottom of the water.

(Problem to be solved by the invention) Although the floating method is more economical than the other two methods at deep water points, it cannot avoid shaking due to waves and requires maintenance for mooring. Furthermore, since the transmittance is higher than the other two methods, it is impossible to use a quiet area behind the structure.

Although the Tsukishima method has the most proven track record and is relatively economical in shallow water locations, it has a large impact on the surrounding environment during and after the construction of the Tsukishima, and in some cases may even lead to environmental deterioration. In addition, the construction period is generally long (and the usable area of the facility is limited to the upper part, which is disadvantageous for marine recreation facilities and marine resort facilities.

On the other hand, the bottom landing method has the advantages of not being shaken by waves, being able to use the upper part and inside of the structure, requiring almost no maintenance or management, and being able to easily respond to changes in overburden loads. .

However, conventional bottom landing methods are significantly affected by earthquakes, are subject to restrictions due to ground conditions such as the need for ground improvement, or are impermeable to structures that prevent seawater exchange. There was a problem that it had a big impact on the natural environment.

The present invention was proposed in view of the problems of the conventional bottom landing method, and its purpose is to reduce horizontal force caused by waves, reduce ground pressure, and exhibit a seismic isolation effect.
An object of the present invention is to provide a soft-bottomed offshore structure that does not require ground improvement and does not adversely affect the surrounding environment.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the soft-bottomed offshore structure according to the present invention has a double permeable type structure with an inner and outer structure, in which a floating water retarding section is interposed in the middle, around a floating body foundation. The wave-dissipating structure is integrally erected, and the outer wave-dissipating structure is provided with a fluid inflow/outflow opening that communicates with the water retarding section and opens to the open sea, and an upper structure is installed on the inner and outer wave-dissipating structure. It is constructed based on the following.

In the present invention, in order to reduce overtopping waves, it is preferable that the outer circumferential surfaces of the inner and outer wave-dissipating structures be formed into concave curved surfaces that continuously extend upward and inward.

(Function) According to the present invention, when the fluid of the incident wave passes through the dual inner and outer transparent wave-absorbing structure, energy loss of the incident wave occurs twice, and the energy loss occurs between the inner and outer wave-absorbing structures. Outflow of fluid from a fluid inflow/outflow opening communicating with a retarding section interposed in the
The inflow acts to cancel out water level fluctuations due to incident waves from the outer wave-dissipating structure, thereby reducing reflectance and wave power.

Furthermore, since the fluid outflow/inflow opening provided in the outer wave-dissipating structure is in communication with the retarding section interposed between the dual inner and outer wave-dissipating structures, water particles from waves incident on the retarding section are Pressure is released through the opening and the reflectance is significantly reduced.

In addition, by connecting the fluid inflow and outflow openings to the water retarding section, several natural periods are formed in the retarding section as described later, and as a result, wave force is reduced against incident waves with a wide period range. It becomes possible to reduce the reflection rate and reduce the reflectance.

In this way, the horizontal force caused by waves acting on the offshore structure is reduced, and the buoyant force acting on the floating foundation of the offshore structure minimizes the ground pressure of the offshore structure and stabilizes it against waves. It allows sliding during earthquakes of the above magnitude and provides a seismic isolation effect for structures and installed facilities.

In addition, since the outer circumferential surface of the inner and outer wave-dissipating structure is formed into a concave curved surface that continuously extends upward and inward, the incident wave moves upward along the concave curved surface, and the movement of the incident wave Energy is converted to potential energy and wave overtopping is reduced.

Moreover, since the shape of this concave curved surface is close to the motion locus of the water particles of the incident traveling wave, the energy of the incident waves is smoothly converted into potential energy, which also reduces the reflectance.

(Example) The present invention will be described below with reference to the illustrated embodiments.

(1) is a floating body foundation that has landed on a mound (3) built on the conventional seabed ground (2).
), transparent type double inner and outer wave dissipating structures (5) and (6) each having holes (4) or slits are formed in such a way that a water retarding part (7) is interposed between the two. The foundation part (1
) and - are erected on the body.

A fluid inflow/outflow opening (8) that communicates with the water retarding section (7) and opens to the open sea is provided at the lower part of the outer wave-dissipating structure (6).

Each of the internal and external wave dissipating structures (5:l (6) has a horizontal slit (4') as shown in Figure 3 outside the hole (4)) and a vertical slit (4#) as shown in Figure 4. Each outer surface is formed into a concave curved surface that continuously extends upward and inward.

The inner and outer wave-dissipating structures (5) (6) are connected by a horizontal wall (9) (see Figure 2), and the inner and outer wave-dissipating structures (5) (6), as well as A deck part (11) is supported by an inner structure (10) erected at the center of the floating body foundation part (1), and a loading facility (12) is arranged on the deck part (11). .

(13) in the figure is the internal water area of the structure.

The illustrated embodiment is constructed as described above so that the fluid of the incident wave (14) passes through the holes (4) or slits in the outer wave-dampening structure (6) and the inner wave-dampening structure (5). At this time, energy loss occurs twice due to rapid contraction and expansion of the passing fluid, and the transmittance is significantly reduced.

In addition, the outflow and inflow of the fluid obtained through the fluid outflow and inflow opening (8) communicating with the retarding section (7) provided between the inner wave dissipating structures (5) and (6) is carried out by the outer wave dissipating structure. Structure (6)
This acts to cancel out water level fluctuations in the water retarding section (7) due to more incident waves, reducing reflectance and wave power.

Furthermore, since the water retarding section (7) is connected to the fluid inflow/outflow opening (8) provided in the outer wave dissipating structure (6),
Although the pressure caused by the water particles of the waves incident on the water retarding section (7) shows a large value in the impermeable exit field, it is released through the opening section (7), and therefore, there are no overlapping waves. Reflectance is significantly reduced.

Furthermore, when the water retarding section (7) is constituted by a conventional transparent wall having voids, the reflected wave has one natural period determined by the width and porosity of the water retarding section. For example, by providing the fluid inflow and outflow openings (8), it becomes possible to form several natural periods in the water retarding section (7). (This phenomenon is Mult
It's called iresonance.

Reference N, Aibli and et al+ 1982
The Kvaerner Multiresonan
t OWC, The Znd International
alSymposium on Wave Energ
y 1Jtilization.

(Trondheim, Norway) This allows for a phase effect that cancels the incident wave and the reflected wave over a wide period range of the incident wave, since the incident wave has various wave periods.

In other words, it is possible to reduce wave force and reflectance for incident waves in a wide period range.

Furthermore, since the outer circumferential surface of the inner wave-dissipating structure (5) (6) is formed into a concave curved surface that continuously extends upward and inward, the incident wave is pushed upward along this concave curved surface. The kinetic energy of the incident wave (14) is converted into potential energy, thus reducing wave overtopping.

When the overtopping is small in this way, the wave transmittance is reduced accordingly, and the height of the deck portion (11) can be reduced, which is economical.

In the figure, (15) indicates the first transmitted wave, and (16) indicates the second transmitted wave.

Although FIG. 5 shows the case where the planar shape of the marine structure is circular, and FIG. 6 shows the case where it is rectangular, it is of course possible to take any planar shape. Note that when the offshore structure has a circular planar shape as shown in FIG. 5, it is not affected by the incident angle of the incident wave.

In the figure, parts equivalent to those of the above embodiment are given the same reference numerals.

According to the offshore structure shown in the above embodiment, by actively utilizing the buoyancy obtained from the floating body foundation, the grounding pressure of the foundation caused by the conventional bottoming method can be suppressed to a low level, and acceleration of a certain scale or more can be lowered from the ground. When input is applied, sliding occurs between the structure and the supporting ground, thereby blocking the earthquake input, which can be expected to have a so-called seismic isolation effect. Furthermore, reducing the ground pressure in this way means that the support capacity of the supporting ground may be small.
The cost of improving the supporting ground will be significantly reduced.

What should be noted here is that when lowering the ground pressure, there is a lower limit to the same pressure.

That is, a horizontal force due to waves acts on the offshore structure, and the horizontal force needs to stabilize the structure without causing it to slide. This determines the minimum required ground pressure of the offshore structure.

According to the embodiment, the floating body foundation (1) is surrounded by a dual-internal and external transparent wave-dissipating structure (5) (6) with the retarding part (7) interposed in the middle. wave-dissipating structure (6)
By providing a fluid inflow/outflow opening (8) that communicates with the water retarding section (7) and opens to the open sea, wave force is significantly reduced compared to conventional caisson-type bottom-mounted structures. It is possible to reduce the ground pressure as much as possible and further improve the seismic isolation effect of soft-bottomed offshore structures.

In addition, with caisson-type bottom-mounted offshore structures, incident waves are completely reflected, so a calm area is formed behind the structure, but there is no exchange of seawater, which has a large impact on the natural environment. According to the embodiment, the internal and external wave dissipating structures (5) (
Seawater can be exchanged freely through the holes (4) or slits provided in 6), so the impact on the natural environment is small, and the reflectance of incident waves (14) is small, so the front of the structure is similar to conventional structures. The wave height distribution becomes smaller.

(Effects of the Invention) According to the present invention, as described above, a dual transmission type wave-dissipating structure (inside and outside) with a water retarding section interposed in the middle is integrally erected around the floating body foundation, and the outer wave-dissipating structure communicates with the water retarding section,
In addition, by providing fluid inflow and outflow openings that open to the open sea, it is possible to significantly reduce horizontal wave force and reflectance and transmittance for incident waves in a wide period range, By incorporating a soft bottoming method that actively utilizes buoyancy, a marine structure is constructed that exhibits a seismic isolation effect during an earthquake.

In addition, the double internal and external transparent wave-dissipating structure enables conversion of seawater inside and outside the structure, which was impossible with conventional bottom-mounted offshore structures, eliminating changes in the natural environment.
In addition, scouring that occurs around the structure can be prevented.

Furthermore, since the ground pressure is lower than that of conventional bottom-mounted offshore structures, there is no need to improve the existing ground, reducing construction costs.

Furthermore, the floating foundation not only provides buoyancy when completed, but also allows the interior space to be used as a facility, and during construction, can be used as a scaffolding floating body, so construction can be carried out on the sea with the superstructure floating. This shortens the construction period and reduces construction costs.

Furthermore, the invention as claimed in claim 2, wherein the water area inside the marine structure exchanges seawater with the outside and is quiet, is a space suitable for a marine facility. By forming the concave curved surface that extends directionally and continuously, it is possible to reduce wave overtopping, reduce wave transmittance, and lower the height of the deck of the upper structure supported by the wave-dissipating structure. It has been made possible.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing an embodiment of the soft-bottomed marine structure according to the present invention, Fig. 2 is an exploded slope view of the main part thereof, and Figs. 3 and 4 are perspective views of the wave-dissipating structure, respectively. 5 and 6 are perspective views of soft-bottomed marine structures having circular and rectangular planar shapes, respectively. CI) - one floating body foundation, (4) - hole, (4')
(4')-m-slit, (5)-inner wave-dissipating structure,
(6) - Outer wave dissipating structure, (7) - Retarding section, (8)
---Fluid inflow/outflow opening, (11) ---Deck portion. Agent Patent Attorney Shige Okamoto 2 extra-literary inscriptions 3 shogi 4 illustrations 5 feet 1 6 meters

Claims (2)

[Claims] (1) A dual transmission type wave-dissipating structure (internal and external) with a retarding section interposed in the middle is erected around the floating body foundation, and the outer wave-dissipating structure is connected to the retarding section and externally. 1. A soft-bottomed marine structure, comprising: a fluid inflow/outflow opening opening into the sea; and an upper structure supported on the inner and outer wave dissipating structures. (2) The soft-bottomed marine structure according to claim 1, wherein the outer circumferential surface of the inner and outer wave-dissipating structure is formed into a concave curved surface that continuously extends upward and inward.