JPS6062318A - Offshore working platform - Google Patents

Abstract

PURPOSE:To cut down the cost of construction for an offshore working platform by a method in which vertically movable legs are provided to a pontoon in which upper deck is supported thrugh struts on a water-chargeable body, and they are fixed during the working period in such a way that the varying position B of water level is within the range of the strut portion. CONSTITUTION:An offshore working platform is towed to a given position and positioned by an anchor 9, and legs 2 are lowered by an elevator 3 and driven into the ground of seabed. A pontoon 1 and the legs 2 are freed, water is charged into the body 4 to lower the pontoon 1, and the body 4 is sunk into water. Where the varying position B of water level is within the range of struts 5 portion during the ebb and flow period, the pontoon 1 and the legs 2 are fixed. Since the pontoon 1 is given a buoyancy, burden of the legs is lessened, the elevator used can be miniaturized, and the cost of construction can be reduced.

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention is directed to a method for performing piling, polling, submersion, and other works above the water surface in civil engineering works such as sea berth construction, immersed tunnel construction, and submarine excavation. Regarding the marine workbench used.

[Prior art and its problems]

This offshore work platform has legs that can be raised and lowered, and the pontoon is towed by a tugboat to the destination, lowered to the seabed and fixed, and the pontoon is pushed up from the sea to the air with a jack to maintain a stable state. There is a so-called 0-lift type that performs work with .

By the way, the conventional single-lift offshore work platform is completely lifted up and fixed in the air above the sea, so if the weight of the crane and other equipment increases, a lifting device with a correspondingly larger capacity is required, and it also requires a lifting device with a correspondingly larger capacity. In addition to the depth of the water, this requires long bones to penetrate the soil, making the legs long and extremely expensive to construct. Furthermore, when constructing on improved ground, there are many cases where it is not allowed to penetrate the legs to the supporting layer, creating an extremely unstable situation with conventional methods.

[Purpose of the invention]

The object of the present invention is to eliminate the disadvantages of the conventional example, and because buoyancy can be used, the weight to be supported is much less than the conventional one, resulting in a small lifting capacity and short legs, reducing the construction cost, as well as reducing the burden of water level changes. It is an object of the present invention to provide a marine work platform that can maintain a stable state with minimal oscillation.

[Key points of the invention]

This purpose, according to the present invention, is a marine work platform in which a pontoon is provided with legs that can be raised and lowered, and the pontoon supports an upper deck by connecting members of pillars arranged in parallel at a distance from a water-injectable main body. By fixing the pontoon during operation so that the water level change is located at the connecting member bone, the buoyancy of the pontoon is utilized, and the water level change is achieved by receiving the water level change in the part with many voids.

[Embodiments of the invention]

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

Fig. 1 is a front view showing an embodiment of the marine working platform of the present invention, Fig. 2 is a plan view of the same, and Fig. 3 is a side view of the same. It shows the legs attached so that they can be raised and lowered via the

The pontoon L has a main body 4 that can be injected with water at the bottom, a number of hollow supports 5 are erected from the main body 4 at appropriate intervals, and an upper deck 6 is attached to the upper end of the supports 5. It is something. In other words, the support column 5 serves as a connecting member between the main body portion 4 and the upper differential gear.

Necessary equipment such as a fully rotating crane 7 and an operation room 8 are provided on the upper deck 6, and the four lifting devices 3 of the legs 2 are also provided at each of the four corners of the upper deck 6.

Next, the installation method will be explained. When the main body 4 is towed by a tugboat or the like, water has not yet been injected into the main body 4, the water line is located at the part A in FIG. 1, and the legs 2 are also pulled upward.

In this way, the ship is towed on the sea to a predetermined position, and first, positioning is performed using the anchor 9. Next, the leg 2 is lowered by the lifting device 3 and its tip is driven into the ground, but the reaction force can be taken from the pontoon 1. Once leg 2 is fixed in this way, pontoon 1 and leg 2 are freed, water is poured into main body 4, and pontoon 1 is lowered little by little while keeping balance until the main body tt+<4.
The pontoon 1 and the leg 2 are fixed at a place where the pontoon 1 and the leg 2 are completely submerged in water, and the water level change B during ebb and flow is located at the part of the support 5 which is a connecting moon.

In this way, the pontoon 1 still has buoyancy, and the load applied to the legs 2 will be smaller compared to the conventional case in which the entire pontoon 1 is exposed above the water surface. Since there is no need for the ability to push the water above the water surface, it can be small.

In addition, since the water level changes only in the part of the support column 5 that has many voids, this influence can be minimized, and vertical fluctuations caused by waves and the tide level will be small.

Further, since the leg 2 is only affected by the water level difference and the load change due to the crane 7, a stable state can be maintained even when the sludge layer is thick, even if the leg 2 is inserted deeply.

Furthermore, as another installation method, the leg 2 may be fixed to the pontoon 1 and injected into the main body 4 to submerge the entire body without inserting the tip of the leg 2 into the ground, or the pontoon 1 may be submerged. After that, the lifting device 3 may be operated to insert the leg 2, and the procedure can be selected as appropriate.

When the work is completed, the pontoon 1 and the leg 2 are freed, water is drained from the main body 4, the main body 4 is floated, and the leg 2 is pulled up so that it can be towed.

As described above, the marine work platform of the present invention is equipped with legs that can be raised and lowered on a pontoon, and the weight that must be supported by using the buoyancy of the pontoon when fixed during work can be reduced compared to conventional ones, and the lifting device etc. can also be made small, so construction costs can be greatly reduced. Furthermore, fluctuations due to changes in water level can be suppressed to a small extent, and a stable state can be obtained.

[Brief explanation of drawings]

FIG. 1 is a front view showing an embodiment of the marine working platform of the present invention, FIG. 2 is a plan view of the same, and FIG. 3 is a side view of the same. 1... Pontoon 2... Leg 3... Lifting device 4... Main body 5... Hollow support 6... Upper bar 7... Crane 8... Control room 9... Anchor Applicant Kajima Construction Co., Ltd.

Claims (1)

[Claims] In a marine work platform in which the pontoon is equipped with legs that can be raised and lowered, the pontoon shall support the upper deck by connecting members of pillars arranged in parallel at a distance from the main body that can be injected with water, and the water level shall be maintained at the bones of the connecting members. A marine work platform characterized by being fixed during work so that the change is located.