JPS61106815A - Off-shore working platform - Google Patents

Abstract

PURPOSE:To cause a footing to be lowered to a position deep in a ground, by a method wherein an enclosed space is formed with a leg column, having a hollow part, or a skirt, attached around the footing, and a sea bottom, and high pressure water is fed through the closed space into the hollow part. CONSTITUTION:A leg column 12 of a off-shore working platform is seated on a sea bottom, and an enclosed space 32 is formed with the leg column 12, a footing 14, and a skirt 26. A valve 38 of a means 34 through which the inside and the outside of the space 32 are intercommunicated, and a valve 40 of a means 36, through which the space 32 and a hollow part 28 of the leg column 12 are intercommunicated, are opened. Water at the outside flows in the space 32 through a pipe 34a and branch pipes 34b, 34c to disturb a sedimentary layer H, and a component, with which the sedimentary layer H is formed, is mixed with water. The component, mixed with water, is fed to the leg column 12 and the hollow part 28 through a pipe 36, the sedimentary layer H below the footing 14 is removed, and the footing 14, i.e., a working platform is gradually lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a floating work platform installed in the ocean, lakes, rivers, etc., and particularly relates to a floating work platform used in the ocean.

(Prior Art) A floating work platform is used for mining resources such as oil and natural gas offshore, and includes a work deck, a plurality of pedestals supporting the work deck, and footings attached to each pedestal. Be prepared.

A floating work platform installed in the ocean, that is, an offshore work platform, is installed so that the footing touches the bottom of the nose and the work deck is located on the sea. However, since the sea floor is defined by the surface of a sedimentary layer of sediment, sludge, dust, algae, etc., the footing +1 is placed on the sedimentary layer. It will be placed. From this, it can be determined that the wave force, wind force is strong, or the current speed is 1. % water area: ′1,
The offshore work platform will be placed in an unstable situation.

(Objective of the Invention) Accordingly, one object of the present invention is to provide a floating work platform that allows the footing to reach the bedrock below the sedimentary layer or a deep position in the sedimentary layer.

(Structure of the Invention) A floating work platform according to the present invention is provided with a hollow portion in at least one of a plurality of pedestals that support a work deck on water and a footing attached to each pedestal. A skirt is provided surrounding the pedestal or footing to form a sealed space around the pedestal or footing when the footing is placed on the bottom, and a first communication means for communicating the inside and outside of the sealed space and the hollow portion. The present invention is characterized in that a second communication means is provided for allowing one communication between the air conditioner and the sealed space.

(Operations and Effects of the Invention) According to the present invention, in order to install a floating work platform, the footing and the skirt are connected to the bottom of the water, that is, the bank.
Upon landing on the stack, the skirt pierces the stack to form an enclosed space around the pedestal or footing.

Since the water pressure near the bottom of the water is higher than the pressure in the hollow portion, high-pressure water flows into the closed space from the outside via the first communication means, and the closed space is closed via the second communication means. Water flows out from the space into the hollow portion. At this time, the flow of water in the closed space disturbs the deposited layer under the footing and is carried along with the water to the hollow portion through the front pipe. In this way, the deposited layer under the footing is removed, and the footing is lowered as it is removed. In this way, the footing can reach deep into bedrock or sedimentary layers. Furthermore, since the difference between the pressure within the hollow portion and the pressure near the bottom of the water is utilized, no power is required to generate the flow of the pre-distributed water.

(Embodiments of the Invention) Features of the present invention will become clearer from the following description of the illustrated embodiments.

Referring to FIGS. 1 and 2, the floating work platform IO according to the present invention has a plurality of pedestals (four pedestals in the illustrated example) 12.
, a footing 14 attached to each pedestal and resting on the bottom of the water, and a work deck 16 supported on the water by a plurality of pedestals 12.

The work deck 16 includes a plurality of tubular vertical members 17a whose upper ends are fixed to the work deck 16 and whose lower ends are fixed to each pedestal 12, and a plurality of pipes connected to each vertical member and a place 18, which will be described later, located at the lowest point. It is supported by the pillar 12 via a tubular diagonal member 17b.

The floating work platform 1O is usually installed so that the water surface is at approximately the center level of the vertical member 17a.
Used for mining operations such as natural gas.

As shown in FIG. 2, the four pillars 12 extend along the ridgeline of a regular square pyramid, and adjacent pillars 12 are connected to each other via a plurality of places 18 spaced apart in the vertical direction. has been done.

As shown in FIG. 3, the footing 14 is composed of an annular portion 20 perpendicular to the axis of the pedestal l2 and a central portion 22 surrounded by and integrally formed with the annular portion.

Pillar 12, place 18, annular part 20 and central part 2
2 are both made of cylinders of concrete a.
The pedestal 12 is closed at its upper end and open at its lower end.

Further, the upper end of the central portion 22 of the footing is open.

0 pillar 12 whose lower end is closed and the central part 22 are 1M
- an inner diameter and an outer diameter of Instead of being made of concrete, the one-leg column 12, place 18, and footing 14 connected to the can be made of steel, as are the working deck 16, the vertical members 17a, and the diagonal members 17b. Moreover, instead of configuring these with a cylindrical body or a tubular body, the hollow portion 2 described below
8 or a solid body with a hollow portion 30.

J″l The skirt 26 surrounding the footing 14 is connected to the annular portion 20.
It is attached in contact with the outer peripheral surface of the

The skirt 26 shown in FIG. 3 has its lower end defining a wet open surface located above the level of the bottom of the central portion 22 of the footing. Note that the skirt 26 can also be attached to the pedestal 12.

When installing the floating work No. 1 O by injecting the palast water B into a part of the hollow part 28 of the pedestal 12 and all of the hollow part 30 of the central part 22, a part of the annular part 20 of the footing,
The bottom of the center part 22 and the lower end of the skirt 26 are
It lands on the bottom of the water defined by a sedimentary layer H of sludge, dust, algae debris, etc. At this time, a closed space 32 is formed around the footing 14, that is, the annular portion 20. In this example,
The closed space 32 is formed at a position approximately 120 m below the water surface.

As described above, the footing 14 shown in FIG.
are arranged coaxially, respectively, but as shown in FIG. It can be placed in line with the ocean floor.

In the example shown in FIG. 4, the skirt 26 is formed integrally with the annular portion 20 as well as the center portion 22, and the lower ends or bottoms of these two sides are located on substantially the same plane. Also,
In the footing 14 shown in FIG. 5, the annular portion 20 thereof has a rectangular cross section rather than a circle, and the skirt 26 is formed integrally with the annular portion 20, as in the example shown in FIG. Unlike the example of FIG. 4, the lower end of the skirt 26 is located below the bottoms of the annular portion 20 and the central portion 22, which are on the same plane.

The annular portion 20 of the footing is provided with a first communication means 34 that communicates the inside of the closed space 32 with the outside, that is, the outside world, and the central portion of the footing and the pedestal 12 are provided with a first communication means 34 that communicates between the closed space 32 and the pedestal. A second communication means 36 is arranged to communicate with the hollow portions 28 of 12.

The first communication means 34 includes a pipe 34a extending from the inside of the annular part 20 of the footing to the outside, and a ring-shaped first branch that communicates with the wire pipe and extends inside the annular part 20 in the circumferential direction. A pipe 34b and a plurality of second branch pipes 3 communicating with the first branch pipe and opening at the bottom portion of the annular portion 20.
4c. A plurality of pipes 34a8 and second branch pipes 34c can be provided at intervals in the circumferential direction of the first branch pipe 34b.

On the other hand, the second communication means 36 has an upper end that opens at the hollow portion 28 above the water surface of the ballast water B, and extends downward through the hollow portion 28 and the hollow portion 30 of the central portion 22 and opens at the bottom of the central portion 22. a tube 3 having an open lower end;
Consisting of 6a.

It is desirable to provide valves 38 and 40 near the upper end of the tube 34a that projects to the outside and near the upper end of the tube 36a.

The water pressure inside and outside the sealed space 32 near the seabed is higher than the pressure approximately equal to the atmospheric pressure inside the hollow portion 28. Therefore, when both valves 38 and 40 are opened, water from the outside world flows into the pipe 34a and the first and flows into the closed space 32 through the second branch pipes 34b and 34c. At this time, the deposited layer H
The sediment layer H is disturbed by the water flowing toward the sediment layer H, and the components constituting the sediment layer H are mixed with the water due to this disturbance. Said components mixed with water are conveyed to the hollow part 28 of the pedestal 12 via the tube 36a. In addition, in order to prevent the components of the deposited layer H from entering the lower opening of the tube 36a when landing on the bottom,
Preferably, a remotely removable shielding plate 41 is arranged at the bottom of the central part 22.

Such a series of operations is performed using the difference between the pressure inside and outside the closed space 32 and the pressure inside the hollow portion 28, so no power is required at all.
It can be stopped by closing at least one of them.

By removing the sediment aWH under the footing 14 in this manner, the footing 14 and therefore the floating platform 10 are gradually lowered during its removal. When the lowering speeds of the four footings 14 are different, one or both of the valves are closed or the opening degree is adjusted with respect to the first and second communication means. By doing so, the flow of water in the first and second communication means 34, 36 is temporarily stopped or the flow rate is adjusted.Thereby, the lowering speed is adjusted, and the floating platform caused by the difference in the lowering speed is 10 can be corrected.

The mixture of water stored in the hollow part 28 of the pedestal 12 and the components of the deposited layer H is produced by a slurry pump 42 arranged above the water surface of the ballast water B in the hollow part 28 and connected to the pump. It can be drained via a hose 44 extending to the working deck 16. Furthermore, if a submersible pump is used instead of the slurry pump, the components of the deposited layer H can be evacuated into the hollow portion 28, 30, and only water can be discharged. Thereby, the water level of the ballast water can be maintained constant. Note that it is desirable to make the flow rate in the pipe 36a and the flow rate in the hose 44 the same in order to keep the flow velocity in the IP 36a constant. The hollow portion 30 or the hollow portion 28 of the pedestal 12 may be arranged to open into the ballast water; however,
In this case, the water pressure of the ballast water is loaded, so tr! The flow rate within 36a may be reduced. moreover,
The upper end of the tube 36a may be opened into the hollow portion of the annular portion 20. In this case, the pump as described above may be inserted into the annular portion 20.
Needless to say, it is placed in the hollow portion of the.

In this way, the footing 14 is 4a! It reaches the deep position of H or the bedrock below the sedimentary layer H, and as a result, the floating work platform 10 is installed in an extremely stable state.

By the way, depending on the properties of the sediment layer H, the skirt 26 may be buried in the sediment layer H and the inside thereof may be filled with components of the sediment layer H when the skirt 26 reaches the bottom. In such a case, the water flow resistance between the WSL communication means 34 and the second communication means 36 becomes extremely large, and there is a possibility that the water will not flow smoothly.

For this purpose, a high-pressure water supply pipe extending to the footing 14 through the interior of the pedestal 12 is arranged E, and a plurality of nozzles communicating with the high-pressure water supply pipe are provided at the bottom of the footing 14. The high pressure water supply pipe has one end connected to the work deck 16.
connected to a high pressure water supply (not shown) located above.

In the example of FIG. 3, the other end 46 of the pair of high-pressure water supply pipes 46
a extends into the annular portion 20 through the boundary wall between the annular portion 20 and the central portion 22, and is curved along the bottom inner surface of the annular portion. On the other hand, a plurality of nozzles 48a are formed at the bottom of the annular portion 20 and open at the outer surface thereof. The other end 46a of the high-pressure water supply pipe is provided with a plurality of holes (not shown) that align with the plurality of jet ports 48a. 4-A curved branch pipe 47 branched from the other end of the wooden high-pressure water supply pipe 47
The zero-branch pipe 47a, which is disposed along the inner surface of the closed bottom of the central portion 22, is also provided with a plurality of holes (not shown) that align with the plurality of nozzles 48b opening on the outer surface of the bottom of the central portion 22. It is being

The nozzles 48a, 48b can be arranged such that their centers lie within a plane that includes, for example, the opening centers of the second branch pipe 34c and the pipe 36a and that extends along the pillar.

As a result, the nozzle 48a.

When high-pressure water is spouted from 48b, the pile u! A groove-shaped sealed space (not shown) can be formed in the L layer H, and a second
Water is introduced into the groove-shaped space from the branch pipe 34c. As a result, the sealed space is expanded and 1
Disturbance and discharge of the deposited layer H due to smooth water flow is realized. It goes without saying that the nozzle openings are arranged so that they open within the range defined by the skirt 26, but they can also be arranged irregularly within the range.

In the example shown in FIG. 4, the pair of high-pressure water supply pipes 46 and the corresponding spout 48a are the same as the example shown in FIG. 3, but the high-pressure water supply pipe 47 has a central portion with a flat bottom. A non-curved branch pipe 47a is arranged along the inner surface of the bottom portion of the pipe 22.

In addition, in the example shown in FIG. 5, the high-pressure water supply pipe 50 is bent at an almost right angle and extends linearly at the other end j.□fi.
50a, the other end of which is embedded in the bottom of the footings from the central part 22 to the annular part 20 around it. The other end 50a has a central portion 2.
2 and a plurality of nozzles 5 opening on the bottom outer surface of the annular portion 20
A hole (not shown) aligned with 2° is provided.

Further, according to the high-pressure water supply mechanism as described above, the valve 38 of the first communication means 34 is closed and the second communication means 34 is closed.
By opening the valve 40 of No. 6 and injecting high-pressure water toward the deposited layer H, the deposited layer RH can be disturbed. By introducing high-pressure water into the closed space 32, the pressure in the space increases, and as a result, the disturbed deposited MH
The components together with high aqua regia are discharged from the closed space 32 through the pipe 36&.

[Brief explanation of the drawing]

FIG. 1 is a front view of a floating work platform according to the present invention, FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. 1, and FIG. 3 is a pedestal,
Partially enlarged sectional view of the footing and skirt, Figure 4 and! Figure s5 is a partially enlarged sectional view similar to Figure 2, showing other examples of the footing and skirt, respectively. LO: floating work platform, 12: pedestal, 14; footing, 16 work deck, 20, 22
: Annular part and center part of footing, 26: Skirt, 2B, 30: Hollow part. 32: v, closed space; 34: first communication means. 34a, 34b, 34c: pipe, first branch pipe fJ
J2 branch pipe, 36: second communication means, 36a: pipe. 38, 40: Valve, 46.47, 50; High pressure water supply pipe, 48a, 48b, 52: Spout. Agent Patent Attorney Yoshi Matsunaga Figure 1 Figure 2 I4 Figure 4 Figure 5

Claims (4)

[Claims] (1) A plurality of pedestals and footings that are attached to each pedestal and rest on the bottom of the water, at least one of which has a hollow portion, and a work deck that is supported on the water by the pedestals. , a skirt that is provided surrounding the pedestal or footing and defines an enclosed space around the pedestal or footing when bottoming out, and first communication means that communicates between the inside and the outside of the enclosed space;
A floating work platform, comprising: second communication means for communicating the closed space and the hollow portion. (2) The floating work platform according to claim (1), wherein the first communication means and the second communication means are each provided with a valve. (3) The footing consists of a hollow annular part and a central part surrounded by and integrally formed with the annular part and connected to the pillar, and the first communication means is connected to the annular part. a pipe extending from the inside to the outside; a first branch pipe communicating with the pipe and extending in the circumferential direction within the annular portion;
and a plurality of second branch pipes that communicate with the branch pipes and open at the bottom of the annular part, and the second communication means has one end that opens in the hollow part and a plurality of second branch pipes that open at the bottom of the central part. The floating work platform according to claim 1, comprising a tube having the other end open. (4) A plurality of pedestals and footings that are attached to each pedestal and rest on the bottom of the water, at least one of which has a hollow portion, and a work deck that is supported on the water by the pedestals. , a skirt that is provided surrounding the pedestal or footing and defines an enclosed space around the pedestal or footing when bottoming out, and first communication means that communicates between the inside and the outside of the enclosed space;
a second communication means for communicating the closed space and the hollow portion; and a plurality of spouts connected to a high-pressure water supply source, extending through the interior of the pedestal to the footing, and provided at the bottom of the footing. A floating work platform equipped with a communicating high-pressure water supply pipe.