JPH0118678Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The invention provides equipment and mechanical equipment necessary for performing various operations on the water surface, such as piling, boring, submersion, and dredging. Equipped with waves,
The present invention relates to a lifting type offshore work platform that can be temporarily fixed at a desired construction position against tides, wind currents, etc.

[Conventional technology]

Generally, this type of landing lift type offshore work platform is towed to the desired work position with the support column raised.
At the desired work position, drive the lifting device that connects the support and the workbench body to seat the support on the seabed, then raise the workbench along the support and move the workbench to a high position away from the water surface. Since the work begins after fixing the parts, it becomes a safe and highly workable offshore work platform.

However, due to the structure in which the support and the workbench main body are moved up and down relative to each other, a small gap is required between the support and the support guide provided on the workbench main body, which causes the following problems.

In other words, the workbench body is towed with the prop raised to almost the upper limit position, so if the center of gravity of the prop is higher than the prop guide position and the workbench body is shaken due to the influence of waves, the prop will not move in the gap. When the workbench is shaken or worked,
Since the strut sways within the gap under the influence of waves, wind force, tidal currents, etc., an impact load is generated on the cord member of the strut. Furthermore, if the height of the struts becomes uneven due to irregularities on the seabed, if the strut is a lattice frame type, the intersection position of the strut cord and the horizontal member (hereinafter referred to as the point part) may not match the position of the strut guide. At that time, if a moment due to wind force, tidal current, etc. acts on the workbench body, the unbalanced load due to this moment will be applied to the strut cord other than the case part through the strut guide, so it is necessary to further increase the strength of the strut cord. There is a need. However, most of the structural parts of this type of workbench are made of high-strength steel, and the supports in particular are made of the highest grade of high-strength steel, and maximum effort is required to reduce this weight. The reality is that they are being paid.

Therefore, the conventional landing lift type offshore work platform is equipped with a pedestal stabilizing device including a wedge-shaped adjustment wedge, and during towing or standing operation, a wedge-shaped adjustment wedge is provided between the strut cord's fixed point and the strut guide. A proposal has been made to fix the column to the workbench body by inserting an adjustment wedge (see Japanese Utility Model Application Publication No. 17876/1987), but in order to adopt the column stabilizing device, structural issues are required. Significant changes are required, which not only increases design and manufacturing costs, but also requires adjusting the position of the adjustment wedge each time the strut cord is fixed. The work of fixing the poles and supports is extremely troublesome.

[The problem that the idea aims to solve]

The present invention has been developed in view of these conventional drawbacks, and its purpose is to reduce the impact load and unbalanced load acting on the strut cord without requiring major modification of the workbench or troublesome operations. .

[Means to solve the problem]

In other words, the landing lift type offshore work platform of the present invention has the following features:
A workbench main body, a plurality of columns provided to be movable up and down relative to the workbench main body, a foot can provided at the lower part of each support, a jack house provided on the workbench main body, and the A recess for storing a footcan provided on the lower surface of the workbench main body, and a case point portion where the support is composed of a support cord, a horizontal member, and a diagonal wire, and the intersection of the horizontal member and the support cord. In a landing lift type offshore work platform in which the foot cans are arranged at equal intervals in the longitudinal direction of the strut cord, the distance between the foot can and the horizontal member directly above it is the same as the distance between two adjacent point parts, and , the lower guide provided in the workbench body is extended into the recess for storing the footcan so that its length is slightly longer than the interval between two adjacent case points, and the lower guide is provided in the jack house. It is characterized in that the length of the upper guide is slightly longer than the interval between two adjacent case points.

〔Example〕

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

As shown in FIGS. 1 and 2, the workbench main body 1
is supported by a plurality of (three in the case of the present invention) pillars 2.

This support column 2 is called a lattice frame type, and the second
As shown in the figure, three vertically installed strut cords 2
1 are connected by a large number of horizontal members 22 and diagonal wires 23, and the point of intersection is a case point 24.

Moreover, as shown in FIG. 3, the distance h between two adjacent horizontal members 22, 22 is equal.

On the other hand, a footcan 3 is provided at the bottom of the column 2. In the present invention, as shown in FIG. 3, the distance h between the lowest horizontal member 22 and the footcan 3 is set to 22, 22, and when the foot can 3 is stored in a recess 8, which will be described later, the foot can 3 also has the function of the horizontal member 22.
Furthermore, this footcan 3 is fixed between the three support cords 21, and the distance h between the case point part 24a and the case point part 24 directly above it is
The interval h between the two case points 24 is the same.

Further, as shown in FIG. 4, this footcan 3 has a hexagonal shape, and each support cord 21 is arranged at its apex.

On the other hand, as shown in FIG. 3, the jack house 7 installed on the workbench main body 1 has an upper guide 5 at its upper part. Further, a recess 8 for housing the foot can 3 is provided on the lower surface of the workbench main body 1, and a lower guide 6 is installed extending from inside the workbench main body 1 into this recess 8.

Inside the jack house 7, the workbench main body 1 and each support 2 are relatively raised and lowered by a lifting device 4 that engages with a rack 25 provided on each support 2, and each support 2 has an upper part. It is guided by a guide 5 and a lower guide 6.

The lengths of the upper guide 5 and the lower guide 6 are respectively equal to or slightly longer than the interval h between the two adjacent case points 24, 24.

Therefore, even if the workbench main body 1 and the support column 2 move relative to each other, at least one point portion 24 faces each of the upper guide 5 and the lower guide 6.

Also, place the foot canister 3 in the recess 8 of the workbench body 1.
Even when stored in the lower guide 6, the case point 24a of the footcan 3 or the case point 2 directly above
4 will be facing each other.

Next, the operation of the landing lift type offshore work platform according to the present invention will be explained.

During landing work As shown in Figure 2, the workbench is constructed by placing the support columns 2 on the seabed 10, then raising the workbench main body 1 along the support supports 2, and placing the workbench at a high position away from the water surface. The main body 1 is fixed and work is started.

In the case of FIG. 2, since the seabed 10 is inclined, the phase of the case point part 24 of the right column 2 is slightly shifted downward from the case point part 24 of the left column 2, but the vertical guide 5 , 6 is slightly longer than the length of the two adjacent case point parts 24, so the second case point part 24 from the top is connected to the upper guide 5.
In addition, the fourth case point part 24 from the top faces the lower guide 6, so that even if a load due to the influence of waves, wind force, etc. acts on the workbench main body 1, the load will be transferred to the case part part. 24, case part 2
The stress acting on the strut cord portions between the four ends is significantly reduced compared to the stress acting on the case points 24.

That is, as shown in FIG.
A landing lift type offshore work platform will be described in which upper and lower guides 5 and 6 of length h are arranged with respect to columns 2 with an interval of h, and the distance between their centers is 2h.

In FIG. 5, if a wind load is applied in the direction of arrow A, a force of arrow F is applied between the upper guide 5 and the support column 2. Assuming that the distance between the column 2 and the upper guide 5 is g, in this state the column 2 is inclined with respect to the upper guide 5 by θ=tan ⁻¹ g/2h (1).

Regarding the upper guide 5, considering the force F acting between the column 2 and the workbench body 1 and the deformation of the column 2, when the force F is small, F is supported by the upper end 5c of the upper guide 5, and this force Fc The strut cord 21 is bent and deformed by δ between the case points 24. The amount of deformation δ is expressed by the following equation, assuming that the beam is simply supported between case points.

δ=Fch ₃ /48EIc (2) where E is Young's modulus and Ic is the bending rigidity of the strut cord.

As the force F increases, the deformation δ increases,
When a certain force F is applied, the upper guide 5 and the strut cord 21 come into contact at the case point 24.

The amount of deformation δ at this time is related to the inclination of the entire support column 2 as follows: δ = tanθ ), (2), (3)
From the formula, it is expressed as Fc=48EIc/ _h3・δ=12EIcg/ _h3 ...(4).

That is, the force F applied to the upper guide 5 is Fc
Beyond this point, the strut cord 21 and the upper guide 5 come into contact at the point 24. Since the rigidity of the strut cord 21 and the diagonal wire 23 against the axial force can be designed to be sufficiently larger than the bending rigidity of the strut cord 21, most of F minus Fc is
4 through the diagonal wire 23 to the strut cord 21 and other diagonal wires 23.

In reality, the case part 24 is also displaced to some extent by this force, so the force applied to the case part 24 further increases. , F excluding the force Fc acting on the center of the strut cord 21 calculated by equation (4)
−Fc (≡F _N ) may be considered to be added to the case part 24.

According to an actual designed example, the horizontal force F handled by one strut cord 21 of strut 2 is approximately 500.
The distance h between the horizontal members 22 is 6 m, the bending configuration Ic of the support cord 21 is 3×10 ⁵ cm ³ ,
The gap g between the strut cord 21 and the upper guide 5 is 3 cm.
Then, Fc=105 tons. That is, approximately 1/5 of the horizontal force is applied to the strut cord 21 and approximately 4/5 is applied to the case point portion 24.

Regarding towing When towing, as shown in FIG. 3, the workbench main body 1 is towed with the support 2 raised to the upper limit position and the foot can 3 housed in the recess 8 of the workbench main body 1.

At this time, as shown in FIG.
faces the lower guide 6, and the third case point part 24 from the bottom faces the upper guide 5.

Therefore, even if the workbench main body 1 sways due to the influence of waves or the like, the horizontal force applied to the support cord portion will be reduced to a fraction of what it would be during the landing operation.

[Effect of idea]

As described above, the present invention includes a workbench main body, a plurality of supports that are provided to be movable up and down relative to the workbench main body, a foot can provided at the bottom of each supportbeam, and the workbench main body. A jack house provided on the top, a recess for storing a footcan provided on the lower surface of the workbench body, and the support column is composed of a support cord, a horizontal member, and a diagonal wire member,
In addition, in a landing elevating offshore work platform in which the intersection points of the horizontal member and the strut cord are arranged at equal intervals in the longitudinal direction of the strut cord, the foot can and the horizontal member directly above it. In addition to making the spacing the same as the spacing between the two adjacent case points, the lower guide provided in the workbench body is extended into the recess for storing the footcan so that its length is equal to that of the two adjacent case points. The length of the upper guide provided in the jack house was made slightly longer than the interval between the two adjacent case points, so the workbench would not require significant modification or troublesome operation. It becomes possible to significantly reduce the impact load and unbalanced load applied to the strut cord without the need for

[Brief explanation of the drawing]

Fig. 1 is a plan view of a landing elevating type offshore work platform according to the present invention, Fig. 2 is a cross-sectional view of Fig. 1, and Fig. 3 is an enlarged view of the main parts of the landing elevating type offshore work platform according to the present invention. FIG. 4 is a cross-sectional view taken from FIG. 4, and FIG. 5 is a diagram illustrating the principle of the landing lift type offshore work platform according to the present invention. 1... Workbench body, 2... Support, 3... Foot canister, 5... Upper guide, 6... Branch guide,
7... Jacket house, 8... Hollow, 21... Support cord, 22... Horizontal member, 23... Diagonal wire member, 24... Case point part.

Claims (1)

[Scope of utility model registration request] A workbench main body, a plurality of columns provided to be movable up and down relative to the workbench main body, a foot can provided at the bottom of each support, a jack house provided on the workbench main body, and the A recess for storing a footcan provided on the lower surface of the workbench main body, and a case point portion where the support is composed of a support cord, a horizontal member, and a diagonal wire, and is located at the intersection of the horizontal member and the support cord. In a landing lift type offshore work platform in which the foot cans are arranged at equal intervals in the longitudinal direction of the strut cord, the distance between the foot can and the horizontal member directly above it is the same as the distance between two adjacent point parts, and , the lower guide provided in the workbench body is extended into the recess for storing the footcan so that its length is slightly longer than the interval between two adjacent case points, and the lower guide is provided in the jack house. A landing lift type offshore work platform characterized in that the length of the upper guide is slightly longer than the interval between two adjacent point parts.