JPS5820818A - Supporting of landing and elevating type offshore working platform - Google Patents

Abstract

PURPOSE:To avoid the concentration of stress on the projection below the footing of support legs by providing a concaved space into which the projection below the footing is to be positioned in a powdery granule support layer on the seabed ground supporting the support legs of a working platform. CONSTITUTION:A concaved portion 11 is formed in the contact place between the projection 5 below the footing 3 of support legs 4 and a powdery granule layer 6 on the subgrade 7. In this case, the shape of the concaved portion 11 is similar to that of the projection 5. In short, the concaved portion 11 is formed such that the left and right-handed distances l and l' and the vertical distance d become almost same when the axis C of the projection 5 comes right on the center O of the concaved portion 11. A framework 8 prevnts the movement of the powder granule layer 6 toward the direction of arrow F. Thus, the stress of the projection 5 most liable to stress concentration can be dispersed and thereby the degradation of the subgrade 7 in and around the projection 5 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for supporting a landing lift type offshore work platform, and more specifically, a work platform body having a lifting device, and a footing that loosely fits into the work platform body and has a protrusion on the lower surface. The present invention relates to an improvement in a method for supporting a landing lift-type offshore work platform on a base, which comprises at least three support legs fixed to the lower end of the platform.

``When drilling for oil on the continental shelf, etc., a lifting platform is generally used. This landing lift type offshore work platform A
As shown in FIGS. 1 and 2, the workbench main body 2 includes a lifting device 1, and at least three support legs 4 having footings 3 at the lower ends. This footing 6 has an inclined lower surface and a protrusion 5 approximately at the center of the footing 6 in order to receive the full weight of the offshore workbench A and maintain a fixed point upon landing of the support leg 4. There is. By the way, the total weight of the offshore work platform A is 7.0
It is a heavy structure with a weight of 00 to 9,000 tons,
Further, the support legs 4 can extend to a height of 80 m or more. Therefore, in general, when manufacturing such an offshore work platform A, the work platform main body 2 having the lifting device 1 is supported at the bottom of the ditch by boards or the like, and the work platform main body 2 has a length limited by the lifting equipment. The second unit support leg is loosely fitted into the second unit support leg, and the second unit support leg is connected and fixed to the unit support leg. After the assembly is completed, various tests such as applying a preload are carried out to complete the assembly. During the assembly and testing process, all or part of the weight of the offshore work platform A is transferred to the footing 6. It is necessary to support it at the bottom of the beam, which serves as the foundation. In this case, stress concentration is unavoidable due to the relationship between the flat base and the footing 3 having protrusions and inclined surfaces, and the arrangement and shape of the board must be considered.

For this reason, the present inventor previously proposed that a powder layer 6 made of sand or the like as shown in FIG. 3 be disposed between the footing 3 and the base.

By the way, when actually forming such a powder layer 6, it is possible to reduce the amount of powder and granule by using shoes with the minimum necessary thickness, thereby saving labor in forming or removing the powder layer 6. It becomes important to measure the

To be more specific, the base like the bottom of the beam in Figure 3.

A powder layer 6 having a thickness T is formed on the supporting legs 4.
The footing 3 provided at the lower end of the granular material layer 6 is positioned on the upper surface of the powder layer 6. Reference numeral 8 denotes a frame for effectively forming the powder layer 6. In this configuration, the weight of the offshore work platform A is transmitted to the footing 3 provided at the lower end of the support leg 4, but the force acting on the lower surface of the footing 3 is transferred by the powder layer 6 to the beam of the footing 3. The load is distributed over a load bearing area of 1° which is wider than the projected area on the bottom (9). This load bearing area 10. is related to the thickness T of the powder layer 6,
The projected area is significantly larger than the projected area 9. Powder layer 6
The lower surface of the footing 3 is a slope, and even if the projection 5 is provided at the center, it naturally follows the shape and no concentrated stress is applied to the footing 3. Further, since the weight of the offshore work platform A acting on the footing 6 is widely distributed over the load-bearing area 10 on the base 7, there is no fear that the footing 3 or the i-base 7 will be destroyed.

By the way, as mentioned above, the larger the thickness T of the powder layer 6 is, the larger the load bearing area 10 becomes, which is more effective.However, in reality, in order to increase the thickness T, a large amount of powder material is required. Not only does it require a lot of time and effort to form and remove it. Therefore, it is conceivable to reduce the thickness T of the powder layer 6, but in this case, concentrated stress will occur particularly on the lower surface of the protrusion.

The present invention has been made in view of the above, and includes a workbench main body 1 having an elevating device, and a footing 3 that loosely fits into the workbench main body 1 and has a protrusion 5 on the lower surface thereof. In a landing lift type offshore working platform A consisting of three support legs 4, recesses are formed on the base Z supporting the working platform A and at the locations where the protrusions 5 on the lower surface of each footing 6 come into contact. At the same time, a powder layer 6 is provided at least between the lower surface of the footing 6 and the top of the base 7 and excluding the recess, so that the weight of the neck table is supported by the powder layer 6. The purpose of the present invention is to provide a method of supporting a lifting type offshore work platform.

An embodiment of the present invention will be described below with reference to FIG. Third
A concave portion 11 is formed on the base plate 7 with the same reference numerals as in the figure and at a location where the protrusion 5 on the lower surface of the footing 3 comes into contact. The recess 11 preferably has a similar shape to the protrusion 5. That is, when the axis of the protrusion 5 comes directly above the center 0 of the recess 11, the left and right intervals l and l' and the upper and lower intervals d are formed so as to be almost the same.

A powder layer 6 of sand or the like is formed between the lower surface of the footing 3 including the recess 11 and the base 7. 8 is
When a load is applied to the footing 3 of the frame, the powder layer 6 is prevented from moving in the direction of arrow F due to component force.

The powder layer 6 may be replaced with sandbags as long as it is sufficiently far from the footing 6.

FIG. 5 shows another embodiment of the present invention, in which a sandbag 12 is provided to surround a recess 11 provided on the base, and a protrusion 5 of the footing 6 is placed in a section B surrounded by the bag 12 on the core. is positioned, and a powder layer 6' is formed around the outer periphery.

As is clear from the above description, according to the present invention, the recess 11 is provided on the base plate 7, and the protrusion 5 on the lower surface of the footing 6 is positioned on the recess 11. Since the stress can be dispersed or eliminated, there is no fear that the base 7 around the protrusion 5 of the footing 3 will be destroyed.

Therefore, the amount of powder and granules can be reduced, and the powder and granule layer 6
It is possible to save labor in forming and removing.

Of course, the present invention is not limited to the above embodiments,
It is clear that various changes can be made without departing from the concept.

[Brief explanation of the drawing]

Figure 1 is a side view of the landing lift type offshore work platform, Figure 2 is the side view of the
Figure 3 is an enlarged view of part C, Figure 3 is an enlarged explanatory view of how to support an offshore working platform using a powder layer, and Figures 4 and 5 each show an example of the method of supporting an offshore working platform according to the present invention. FIG. DESCRIPTION OF SYMBOLS 1... Lifting device, 2... Workbench main body, 3... Footing, 4... Support leg, 5... Protrusion, 7... Base, 8... Frame, 11... ... recess, 12... sandbag. Agent Patent Attorney Shin Ogawa − Patent Attorney Ken Noguchi Teru Patent Attorney Kazuhiko Saishita Figure 4 Figure 5

Claims (1)

[Claims] A workbench main body having a lifting device is loosely fitted into the workbench main body,
and a landing lift type offshore work platform comprising at least three support legs having a footing fixed to the lower end thereof, the footing having a protrusion on the lower surface thereof, the platform being on a base supporting the work platform, and having a protrusion on the lower surface of each of the footings. Concave portions are provided at the contact points, and a powder layer is provided at least between the lower surface of the footing and the base upper stop, excluding the concave portions, and the workbench is heated by the base through the powder layer. A method for supporting a landing lift type offshore work platform characterized by supporting weight.