JP2012107399A - Grab frame - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grab frame by which a contact accident between the grab frame and a grab bucket hardly occurs.SOLUTION: An intermediate frame 18 is installed between a main frame 12 and an anchor chain 12 in a grab frame 10. The intermediate frame 18 forms a similar figure to the main frame 12 and has a larger area of the inside of frame than the main frame 12. Rolling-up and warping of a pollution prevention curtain 14 can be suppressed by the rigidity of the intermediate frame 18 so that the grab frame 10 can be maintained in an external shape close to the original shape when being lowered in the quiet sea naturally. This reduces the occurrence rate of a contact accident between a grab bucket and the pollution prevention curtain 14. And, because the work area at the lower part than the intermediate frame 18 expands, operation burden of an operator who operates to prevent the grab bucket from contacting with the pollution prevention curtain 14 can be reduced, and work efficiency can be increased.

Description

The present invention relates to a grab frame for preventing diffusion of contaminating particles in a grab dredge.

In the field of offshore civil engineering work, there is a work type called dredging that crawls the bottom of the sea, and among them, grab dredge that uses a grab bucket to excavate the bottom of the sea is often used. Grab dredging was made with consideration for the environment, such as laying a grab frame around the dredged area and using a grab bucket in the frame so that the turbidity of the seawater (polluted particles) generated during excavation would not diffuse into the surrounding sea area. Construction method is adopted. A general grab frame is composed of a float part floating on the sea surface, a curtain part hanging down in the sea, and a weight chain. The curtain part is flexible and easy to handle, but on the other hand, it is prone to drowning and bending due to the influence of tidal currents, wake waves and convection caused by operation of the grab bucket. Accidents that are damaged by contact with If careful attention is paid to the operation of the grab bucket in order to avoid such an accident, an excessive degree of skill is required for the operation, and further problems such as a significant reduction in work efficiency occur.

In order to solve such a problem, conventionally, a technique for preventing the curtain portion from curling or bending has been proposed. For example, Patent Document 1 discloses that a float is provided at an appropriate interval in an obliquely stretched curtain portion, and a buoyancy that acts on the float attempts to expand the curtain portion outward, particularly in the frame of the curtain portion. A technique for preventing the bending of the sheet is disclosed. In Patent Document 2, a rigid bottom frame is provided at the lower end portion of the curtain portion, and the upper and lower end portions of the curtain portion are fixed by the main frame and the bottom frame, respectively, so that the outer shape of the curtain portion is maintained. A technique for preventing the above is disclosed.

Published Utility Model No. 3-69028 Utility Model Registration No. 3145479

By the way, in the technique disclosed in Patent Document 1, it is necessary to provide ballasts at appropriate intervals so that the buoyancy generated by the float provided in the curtain portion does not lift the curtain portion. This is the weight of the entire grab frame. This increases the burden of installing and removing the grab frame. On the other hand, in the technique disclosed in Patent Document 2, since it is a rigid body, the bottom frame does not conform to the unevenness of the seabed, and a gap may be formed, so that there is a possibility that contaminant particles may diffuse from there.
An object of this invention is to provide the grab frame which can solve the subject which could not be solved by these prior arts.

The present invention includes a main frame having a buoyancy generating function, a pollution prevention curtain that hangs down from the main frame and encloses a grab wall area, a weight chain provided at a lower end portion of the pollution prevention curtain, and the main frame. An intermediate frame provided on the pollution prevention curtain is provided between the weight chains in parallel with the main frame, and the main frame and the intermediate frame are similar in plan view, and the inner area of the intermediate frame is A grab frame is provided which is larger than the area inside the main frame.

The intermediate frame is required to have a rigidity that does not easily deform when a tidal current or the like acts on the pollution prevention curtain. By providing such an intermediate frame in the grab frame, curling and bending of the anti-pollution curtain are suppressed, and the grab frame is maintained in an outer shape close to the original shape when naturally weighted in a calm sea. It becomes like this. As a result, the incidence of contact accidents between the grab bucket and the pollution prevention curtain decreases. In addition, the provision of an intermediate frame with a larger area than the main frame expands the work area below the intermediate frame, reducing the operational burden on the operator who operates the grab bucket so that it does not come into contact with the pollution control curtain. Efficiency is improved.

By providing an intermediate frame between the main frame and the weight chain, there is a gap between the anti-pollution curtain and the bottom of the sea, which can occur when a bottom frame is provided at the lower end of the anti-pollution curtain. Can be avoided

The intermediate frame may be either singular or plural, and can be selectively provided according to the total length of the pollution prevention curtain. In particular, when a grab frame is used at a deep water depth and the entire length of the anti-pollution curtain is very long, it is effective to provide a plurality of intermediate frames at appropriate intervals. When multiple intermediate frames are provided, all of them may be the same size, but if the area inside the frame gradually increases from the main frame side to the weight chain side, the grab bucket and the pollution control curtain Sufficient margin is born between.

In addition, the grab frame has a reinforcing rope stretched between the main frame and the intermediate frame and hung on the pollution control curtain, and a reinforcement rope stretched between the intermediate frame and the weight chain. Also good. By stretching the reinforcing rope, it is possible to more strongly suppress the twisting and bending of the pollution prevention curtain. Further, the anti-contamination curtain has increased impact resistance, and even if it is in contact with the grab bucket, it is not easily damaged.

According to the grab frame provided by the present invention, it is possible to avoid contact accidents between the grab bucket and the pollution prevention curtain, thereby reducing the time and cost required for repair, thereby shortening the construction period and reducing the construction cost. Can be expected. Further, it is possible to prevent the diffusion of the contaminating particles from the damaged part. Furthermore, since a sufficient margin is created between the grab bucket and the pollution prevention curtain, the grab bucket can be operated with peace of mind without worrying about a contact accident, and work efficiency is improved.

(A) Side view and (b) Plan view of grab frame Construction status diagram of grab works using grab frames Construction status diagram of grab works using grab frames Side view of grab frame with multiple intermediate frames

Embodiments of the present invention will be described with reference to the drawings. A grab frame 10 shown in FIG. 1 includes a main frame 12, a pollution prevention curtain 14, a weight chain 16, and an intermediate frame 18 as main elements.

The main frame 12 is a frame formed by arranging a hollow steel pipe so as to be substantially rectangular in a plan view, and generates a function of maintaining the original shape of the grab frame 10 and a buoyancy for levitating the grab frame 10 to the sea surface. It has a function. A float or the like may be installed on the main frame 12 to generate buoyancy.

The pollution prevention curtain 14 has a function of hanging down vertically from the main frame 12 by the weight of the weight chain 16 provided around the lower end and its own weight, surrounding the grab wall area, and shielding the inside and outside of the grab wall area. It is a shield. Since the anti-pollution curtain 14 shields the grab dredging area, it is possible to prevent the diffusion of the pollutant particles generated when excavating soil from the sea floor to the outside of the dredging area, and also when grabbing from the sea surface Diffusion of muddy water overflowing from the bucket can be prevented outside the dredging area.

A plurality of suspension wires 20 provided at substantially equal intervals are connected to the lower end portion of the pollution prevention curtain 14. The hanging wire 20 is used not only for adjusting the height of the lower end portion of the pollution prevention curtain 14 but also for lifting the pollution prevention curtain 14 to the height of the main frame 12 when towing the grab frame 10. The suspension wire 20 can be wound up and down using, for example, a winch provided on the main frame 12.

The intermediate frame 18 is a substantially rectangular frame that is similar to the main frame 12 in plan view, and is provided so as to circulate substantially in the center of the anti-pollution curtain 14 in parallel with the main frame 12. The area inside the intermediate frame 18 is formed to be larger than the area inside the main frame 12. Therefore, the pollution prevention curtain 14 gradually spreads outward from the upper end with the main frame 12 to the approximate center with the intermediate frame 18 and hangs vertically downward from the approximate center to the lower end with the weight chain 16.

The intermediate frame 18 is required to have such rigidity that it is not easily deformed due to the influence of tidal currents or convection during drought. The intermediate frame 18 having such rigidity can maintain the shape of the anti-pollution curtain 14 in a state close to the original shape when dredging, and is caught in the dredging area side due to the influence of tide and convection during dredging. This greatly contributes to the reduction of accidents where the pollution prevention curtain 14 and the grab bucket or wire come into contact. By using the grab frame 10 provided with the intermediate frame 18, the grab bucket can be operated with peace of mind without worrying about a contact accident, and an improvement in work efficiency can be expected.

Moreover, since the part below the intermediate frame 18 of the pollution prevention curtain 14 has spread outside compared with the part above it, a sufficient margin width is produced between the grab bucket and the pollution prevention curtain 14. As a result, the grab bucket can be operated with peace of mind without worrying about a contact accident. From this point of view, work efficiency can be expected to be improved.

A reinforcement rope 22 is stretched on the pollution prevention curtain 14. The reinforcing rope 22 is placed on the outer surface of the pollution prevention curtain 14 between the main frame 12 and the intermediate frame 18 and between the intermediate frame 18 and the weight chain 16. By tensioning the reinforcing rope 22 on the pollution prevention curtain 14, it is possible to more strongly prevent the pollution prevention curtain 14 from twisting or bending than when only the intermediate frame 18 is provided. Further, the anti-contamination curtain 14 has increased impact strength due to the tension of the reinforcing rope 22 and is unlikely to be damaged even if it contacts the grab bucket.

The outflow prevention sheet 24 is a sheet-like shield having a function of blocking the inside and outside of the grab frame 10 above the main frame 12, and is extended in an annular shape along the frame above the main frame 12. The outflow prevention sheet 24 prevents the contaminant particles in the grab frame 10 from flowing out of the frame beyond the main frame 12 due to the influence of tidal currents and waves.

The grab frame 10 is moored to the bow of the grab dredger 30 as shown in FIG. The grab dredger 30 moves using a fixed spud 32 provided at the rear of the hull and a moving spud 34 provided at the center of the hull, and a grab bucket 38 attached to a crane 36 provided at the front of the hull is scheduled. Stop at the place just above the dredging area. During the movement of the grab dredger 30, the pollution prevention curtain 14 is in a state of being pulled up to the sea surface and is dropped toward the seabed when the ship is stopped. When the dredging operation is started, the length of the suspension wire 20 is adjusted according to the water depth as described above, and the inside and outside of the dredging area are shielded so that the bottom end of the pollution prevention curtain 14 and the seabed 40 are in contact with each other.

FIG. 3 shows the state of the grab frame 10 when the seabed 40 is not flat. Since the grab frame 10 has a structure in which the shape is stabilized by an intermediate frame 18 provided substantially at the center of the pollution prevention curtain 14, there is no rigid body at the lower end of the pollution prevention curtain 14 like this conventional grab frame. . Therefore, the lower end portion of the pollution prevention curtain 14 and the weight chain 16 can be easily deformed along the unevenness of the seabed 40, and can be shielded from the seabed 40 without any gap, and an improvement in the pollution prevention effect can be expected. .

When the entire length of the anti-pollution curtain becomes long, such as when a grab frame is used in a deep water depth, the anti-pollution curtain becomes farther away from the main frame as the water depth becomes deeper, and it becomes easy to bend or bend. In such a case, it is effective to provide a plurality of intermediate frames 48 at appropriate intervals in the water depth direction as in the grab frame 50 shown in FIG. Here, the intermediate frame 48 has the same shape and has a constant area within the frame. However, the area within the frame may be increased stepwise as the water depth increases. Also in this case, the reinforcing rope 22 may be stretched between the main frame 12 and the intermediate frame 48 and between the intermediate frame 48 and the weight chain 16. Further, the reinforcing rope 42 can be stretched between the intermediate frames 48.

Although the grab frame 50 is greatly affected by tidal currents at deep water depths, the shape maintaining function provided by the plurality of intermediate frames 48 and the reinforcing ropes 22 and 42 laid against each other is likely to adversely affect safety work. And bending can be suppressed sufficiently.

10, 50 Grab frame 12 Main frame 14, 44 Pollution prevention curtain 16 Weight chain 18, 48 Intermediate frame 22, 42 Reinforcement rope 30 Grab dredger 38 Grab bucket

The present invention includes a main frame having a buoyancy generating function, a pollution prevention curtain that hangs down from the main frame and encloses a grab wall area, a weight chain provided at a lower end portion of the pollution prevention curtain, and the main frame. An intermediate frame provided on the anti-pollution curtain in parallel with the main frame between the weight chains, and reinforcements struck between the main frame and the intermediate frame and between the intermediate frame and the weight chain. A grab frame is provided, comprising a rope , wherein the main frame and the intermediate frame are similar in plan view, and an inner area of the intermediate frame is larger than an inner area of the main frame.

Claims (4)

A main frame having a buoyancy generating function, a pollution prevention curtain hanging from the main frame and enclosing the grab wall area, a weight chain provided at a lower end portion of the pollution prevention curtain, the main frame and the weight chain An intermediate frame provided on the anti-pollution curtain in parallel with the main frame between,
The main frame and the intermediate frame are similar in plan view, and the inner frame area of the intermediate frame is larger than the inner frame area of the main frame. The grab frame according to claim 1, wherein a plurality of the intermediate frames are provided with an interval between the main frame and the weight chain. The grab frame according to claim 2, wherein the intermediate frame has an area inside the frame that gradually increases from the main frame side toward the weight chain side. 4. The anti-pollution curtain is provided with a reinforcing rope stretched between the main frame and the intermediate frame and between the intermediate frame and the weight chain, respectively. The grab frame described.

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