JPS61266715A - Structure for icy sea - Google Patents

Abstract

PURPOSE:To reduce the forces of waves by a method in which plural columns are set in a conical or truncated conical form as a whole, and the intervals, inclined angles, and radii of columns on the sea surface are set to meet specific formulas. CONSTITUTION:Horizontal parts 7 and skew parts 8 are fixed between plural columns 5 erected circularly at intervals on the seabed 9 to make up a body portion 12. Columns 6 are fixed to the upsides of the columns 5 to form a heat portion 13 on the body portion in such a way that the sea water surface W is positioned in the head portion 13. The interval (d), inclined angle (alpha), and radius (r) of the columns 6 are set to meet the following formulas (1), (2), and (3). d<=0.4(Eh<3>/12(1-nu<2>)rhoomega)<1/4>...(1), r(1-costheta)<=2.5<D...(2), sintheta>=tanalpha/2.145...(3), where E is the elasticity of sea water, h is thickness of ice, nu is Poisson's ratio of sea water, rhoomega is density of sea water, and D is diameter of column 6.

Description

[Detailed description of the invention] (Margin below) [Technical field of invention] TECHNICAL FIELD The present invention relates to a structure for water and sea.

[Prior art]

As shown in Fig. 11, the marine structure IA used in the Arctic Ocean has a structure in which a platform 2 is supported by a truncated cone-shaped stand 3, and although the waterflooding conditions are severe, the ice load can be reduced. Furthermore, since the wave height is small, the wave force is small compared to the ice load.

However, due to its structure, it is economically viable only in relatively shallow waters.

On the other hand, the underwater structure IB used in the subarctic ocean is the 12th
As shown in the figure, the platform 2 is supported by a plurality of columns 4.
Although the water-flooding conditions are not very severe, there is a drawback that the ice load is large because the pillars 4 are vertical. Furthermore, since the water depth is large and the wave height is large, wave force cannot be ignored compared to ice load.

[Purpose of the invention]

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to reduce ice loads and wave forces, to have a simple structure and assembly, and to reduce the amount of materials used.

[Structure of the invention]

That is, the structure for water and sea of the present invention has a plurality of columns arranged in a conical or truncated conical shape as a whole, and the distance d between the columns at sea level, the inclination angle a of the columns, and the radius r of the group of columns are The following formulas (i), (2) and (3), that is, r(1-cos θ)≦2.5 X D ・-
・-(2) sin θ≧tan α/2.145
......It is characterized by satisfying (3) at the same time.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

(The following is a blank space) The structure 10 for use in water and sea according to the present invention supports a platform 2 by support columns 11, as shown in FIG.

This support 11 consists of a body 12 and a head 13. As shown in FIG.
is almost truncated conical.

The body 12 is composed of a plurality of columns 5 erected on the seabed 9, a horizontal member 7 fixed between the vessels 5, and an inclined member 8,
Further, the head 13 is constituted by a column 6 fixed on the container 5.

The sea level W is normally located at the head 13. Note that the head 13 may have a conical shape if desired.

The pillars 5 and 6 are hollow or solid, and are formed of m layers or composite m with concrete or the like.

Since the head 13 is so-called cage-shaped, the influence of wave force is reduced.

On the other hand, in order to reduce the ice load, the spacing d between the columns at sea level, the inclination angle a of the columns, and the radius r of the column group are determined as follows (11
, (2) and (3), that is, r(1-cos θ)≦2.5 X D −・−
...(2) sin θ≧tan α/2.145
...It is necessary to satisfy (3) at the same time.

By the way, if the vertical axis is the ice load and the horizontal axis is the ratio d/It of the distance d between the pillars 6 at the water level (sea level W) (see Figure 4) and the characteristic length l of the ice sheet, then the fifth The curve will look like the one shown in the figure.
It can be seen from FIG. 5 that as the number of columns 6 decreases, the water load increases. The reason for this is that a sea ice crushing mode occurs partially in the left and right pillars 6 of the water/marine structure 10 in the direction of drift ice movement, and the minimum number of pillars to eliminate this crushing mode can be found. , (blank below) allows for more economical design.

In addition, the elastic modulus of sea ice is E (Ton/m), and the ice thickness is h.
(M), ν is the Poisson's ratio of sea ice, and ρ is the seawater density.

(Ton/M') is the characteristic length of the ice plate! (M) can be expressed by equation (4).

In other words, It is expressed as

From the experimental results, it is unclear whether crushing mode ■ (see Figure 6) or crushing mode ■ (see Figure 7) will prevail depending on the direction of the drift ice, the thickness and strength of the sea ice, but this is based on past experimental results. It was found that the size of the ice piece, that is, the length j21 of the ice piece in the vertical direction or the length 12 of the ice piece in the horizontal direction is not less than 40% of the characteristic length of the ice plate.

(Left below) Therefore, in the design, the column spacing d at the water level (sea level W)
If it is set as below, the piece of wood will not pass through the column spacing d, and therefore the ice plate will be bent and destroyed by the inclination angle α of the columns, so the hydraulic force will be small.

becomes.

Furthermore, as shown in Fig. 4, if the radius of the head 13 at the water level (sea level (hereinafter referred to as blank space) W) is r, and the degree of expansion of adjacent columns is θ, then d=r ・θ (radians) )=r−sin θ.

Therefore, the column spacing d can also be expressed as follows.

That is, dzr-θ (radians) #r-sin θ Also, the 8th
In the case shown by the symbol B in the figure (case 1), the ice plate is in a crushing mode because the ice plate is in the same fracture state as when it collides with a vertical cylinder.

However, water-ocean model experiments have confirmed that due to the influence of the distance a to the edge of the ice sheet, the water load is smaller than the normal crushing water load (see the margin below) (see Figure 10). .

According to FIG. 10, it can be seen that when a/D is in the range of 0 to 2.35, the hydraulic force is small, but when it exceeds 2.35, the hydraulic force (F)l) increases as a increases. In addition,
The diameter of the pillar is 20cm.

Here, if the diameter of the column 6 is D, and the distance from the center of the column 6 to the end of the ice plate A is a, then under the condition of a / D ≦ 2゜5, the water load is 40% of the normal water load. It is known from the experimental results that the value becomes smaller as follows.

In other words, a=r(1-cos θ)≦2.5 XD −・−(
2) is sufficient.

On the other hand, in the case shown by the symbol C in Fig. 8 (case 2),
The substantial oblique angle β of the column side with respect to the moving direction of the ice plate A is β −jan −′ H/ x (...”・(
It will be 5.

Here, if the radius of the head 13 at the sea level W is r, and the height from the sea level W to the apex K of the head 13 is H, then
(6) H=r-tan α ・・・・・・・・・(7)
Therefore, β=jan −' (r °tan cr/ r °s
tn θ)-tan −' (tanα/sin θ)
-------・+71 By the way, in order for the ice sheet to break due to bending, it is necessary to satisfy the condition of β≦65°.

Therefore, stn θ≧tan α/2.145...
...(3).

Here, E=300000 kg/cm2 h,=150cm ν=0.33 ρω""1.037/m3 D=3000m α=45゛r=1500 an, then =' J9.193 X103=1.74X103am
Therefore, θ≦27.65.

(Left below) ■ (1-cos θ) ≦2.5 X300/1
500=0.5 cos θ≦1 −0.5 =0.
5θ≦60” ■ θ≧sin’ (tan45°/2.145
) = 27.78 Therefore, θ is almost satisfied when it is close to 28 degrees. However, detailed calculations that satisfy ■, ■, and ■ are omitted here.

Therefore, it is preferable that the number of pillars 6 is about 12.

By the way, in the case of the present invention, the pushed ice plate A
This results in the ice load being reduced compared to the conventional structure IB shown in FIG. Further, since the head 13 is so-called cage-shaped, the wave force can be ignored.

〔Effect of the invention〕

As described above, the present invention arranges a plurality of columns in a conical or truncated conical shape as a whole, and the distance between the columns at sea level is d.
, the inclination angle a of the pillars, and the radius r of the pillar group are as follows (1),
Equations (2) and (3), that is, r(1-cos θ)≦2.5XD ・−・−(
2) sin θ≧tan α/2.145
Since (3) is satisfied at the same time, it is possible to reduce ice load and wave force. Furthermore, the structure and assembly are simple, and the amount of materials used can be reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic side view of a structure for water and sea according to the present invention, FIG. 2 is a perspective view of a structure for water and sea according to the present invention, and FIG. Figure 4 is a cross-sectional view of the structure for water and sea according to the present invention at the water level, and Figure 5 shows the ice load and the relationship between the column spacing d at the water level and the ratio of the characteristic length l of the ice plate (the following is a blank space). Figures 6 and 7 are diagrams showing each crushing mode,
Figures 8 and 9 are explanatory diagrams for calculating the influence of drift ice on structures, Figure 10 is a diagram showing the influence of water width on hydraulic power, and Figures 11 and 12 are diagrams for calculating the influence of drift ice on structures. FIG. 2... Platform, 5.6... Pillar, 7... Horizontal member, 8... Inclined member, 9... Seabed, 10...
Structure for water and sea, 11... Support, 12... Body, 13
···head.

Claims (1)

[Claims] A plurality of columns are arranged in a conical or truncated conical shape as a whole,
And the spacing d between the columns at sea level, the inclination angle a of the columns, and the radius r of the column group are expressed by the following formulas (1), (2), and (3), that is, d≦0.4^4√{(Eh ^3)/[12(1-ν^2
)_ρ_ω]}...(1) r(1-cosθ)
≦2.5×D・・・・・・(2) sinθ≧tanα/
2.145... A structure for water and sea, characterized by satisfying (3) at the same time.