JP6709078B2 - Pollution prevention structure used for dredging work - Google Patents

Description

The present invention relates to a pollution prevention structure used for dredging work.

BACKGROUND ART Conventionally, in dredging work by a dredging ship, a pollution prevention frame has been provided to prevent the dredged soil from spreading and contaminating the surrounding water area. In addition, the work of transferring the dredged soil in the pollution prevention frame to an earth carrier using a bucket or the like is performed.

Generally, the earth carrier and the pollution control frame are not anchored by ropes. Therefore, there is a gap between the pollution control frame and the earth carrier. Therefore, when the dredged earth and sand is transferred to the earth carrier, the earth and sand and muddy water spilled from the bucket may fall into the gap and cause pollution.

In view of the above problems, for example, a configuration is disclosed in which an earth transportation ship is provided with a pollution prevention plate that can be lowered by a winch that covers a gap between the earth transportation ship and the pollution prevention frame. The pollution prevention plate is configured so as to be tiltable in the vertical direction by pivotally supporting a base fixed to one end of the earth transport ship. By tilting the tip of the pollution prevention plate downward, the pollution prevention plate can attract the pollution prevention frame to the earth transportation ship and can cover the gap between the earth transportation ship and the pollution prevention frame.

That is, the above-mentioned pollution prevention plate has a function of attracting the pollution prevention frame to the earth transportation ship (pulling function) and a function of covering the gap between the earth transportation ship and the pollution prevention frame to prevent contamination by falling objects (the pollution prevention function). ) Is exhibited (see, for example, Patent Document 1).

Patent No. 5676229 Publication

However, in the pollution prevention plate of Patent Document 1, it may be difficult to draw the pollution prevention frame when the water surface swings greatly, and the pollution prevention function may not be exhibited in some cases. Further, when the water surface oscillates and moves in a direction in which the water surface swings away from each other, the tip end portion of the pollution prevention plate may come into contact with a peripheral member and be damaged.

The pollution prevention plate of Patent Document 1 needs to have a size (length and width) sufficient to draw the pollution prevention frame. Further, in order to attach the pollution prevention plate to the earthmoving ship, a device such as a winch is additionally required on the earthmoving ship side. Therefore, the device becomes a large-scale device and the cost is high.

An object of one embodiment of the present invention is made in view of the above-mentioned problems, and it is possible to reliably exhibit a pulling function and a pollution preventing function, and to provide a pollution preventing structure used for economical dredging work. To do.

The above issues are
A pollution prevention frame arranged in front of the dredging ship, and an earth transportation ship , which is arranged on the port side of the dredging ship and is arranged in parallel with the dredging ship and the pollution prevention frame, and on which the dredged sand is loaded. It has a structure to prevent pollution of dredging work,
A movable pulley portion that is movable in the vertical direction along a guide rail provided at a position facing the pollution prevention frame on the port side of the earth- moving ship,
A constant pulley portion provided at a position facing the movable pulley portion on the soil carrier side of the pollution prevention frame,
A winding device provided on the dredger,
A towing member for pulling the earth-moving ship to the dredging ship side and the pollution prevention frame side;
Is equipped with
The traction member has a rear end connected to the winding device, an intermediate part is hung on the moving pulley part and the constant pulley part, and a tip end is connected to the earth transporter ,
The connecting portion of the towing member with the earth transporter is located above the moving pulley portion,
The movable pulley portion is arranged so as to change the extending direction of the pulling member extending downward from the connecting portion to a direction toward the constant pulley portion,
The constant pulley unit is arranged so as to change the extending direction of the traction member extending from the moving pulley unit to a direction toward the winding device provided in the dredging boat arranged behind the pollution prevention frame.
This can be solved by the pollution prevention structure used for dredging work.

According to the present invention, it is possible to provide a pollution preventing structure which can surely exhibit the attracting function and the pollution preventing function and which is used for economical dredging work.

It is an overall view showing the state where the pollution prevention structure used for the dredging work according to the embodiment of the present invention is implemented. It is a partial expanded perspective view explaining the pollution prevention structure used for the dredging work concerning the embodiment of the present invention. It is a figure explaining the construction procedure of the pollution prevention structure used for the dredging work concerning the embodiment of the present invention.

Hereinafter, an embodiment of a pollution prevention structure used for dredging work according to the present invention will be described. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the duplicate description thereof will be appropriately simplified or omitted. The drawings are not intended to show relative ratios between members or components. Accordingly, the specific dimensions can be determined by one of ordinary skill in the art in light of the following non-limiting embodiments.

FIG. 1 is an overall view showing a state in which a pollution prevention structure used for dredging work according to an embodiment of the present invention is implemented. FIG. 1A shows a plan view, and FIG. 1B shows a front view of the pollution prevention frame as viewed from the front.

INDUSTRIAL APPLICABILITY The present invention has a structure for preventing pollution of a dredging work that is carried out by using a pollution prevention frame 2 arranged in front of a dredger 1 and an earth carrier 3 on which dredged sand is loaded.

The dredger 1 is a grab-type dredger, a backhoe-type dredger, or the like, and has a lifting machine 6. The dredger 1 in the illustrated example is a grab-type dredger, but this is not the only option.

The lifting machine 6 has a grab bucket 61 at its tip, and the grab bucket 61 is connected to the main body 60 of the lifting machine 6 by a boom 62 via a wire 63. The grab bucket 61 is vertically moved up and down by unwinding or winding the wire 63. The main body 60 of the lifting machine 6 is configured to be pivotable, and the boom 62 is pivoted to a predetermined position by pivoting of the main body 60. The boom 62 is configured so that it can be raised and lowered in the vertical direction (vertical direction).

The pollution prevention frame 2 has a float body 21 and a pollution prevention film 22. The float body 21 is assembled in a rectangular shape (quadrangular shape). Specifically, the pollution prevention frame 2 is formed by combining steel pipes having a hollow portion in a rectangular shape as shown in FIG. The steel pipe used may be a square steel pipe or a circular steel pipe.

The pollution prevention film 22 is a film that hangs down from each side of the float body 21 and surrounds the dredging region. A weight material may be attached to the lower end of the pollution prevention film 22.

In the dredging work, first, a pollution prevention frame 2 surrounding the dredging area in a rectangular shape is anchored in front of the dredger 1 by a rope 4 or the like, and an earth transportation ship 3 is anchored by a rope 5 or the like on the port side of the dredger 1. The soil carrier 3 is arranged so as to be juxtaposed with the dredger 1 and the pollution prevention frame 2.

Then, the inside of the pollution prevention frame 2 is dredged by the grab bucket 61 of the lifting machine 6, the grab bucket 61 holding the dredged sand is pulled up to the surface of the water, and the lifting machine 6 is placed so that the grab bucket 61 is on the earth carrier 3. The main body 60 is rotated, the grab bucket 61 is opened, and the dredged earth and sand is loaded on the earth carrier 3.

According to the present invention, during the movement of the grab bucket 61, earth and sand and muddy water spill from the gap of the grab bucket 61 into the gap between the pollution prevention frame 2 and the earth carrier 3, and pollution occurs outside the pollution prevention frame. It is equipped with a structure to prevent this. The point will be described below.

Details of the pollution prevention structure used in the dredging work of the present invention will be described with reference to FIGS. 1 and 2. FIG. 2 is a partially enlarged perspective view illustrating a pollution prevention structure used in the dredging work according to the embodiment of the present invention. FIG. 2A shows a state immediately before the soil transportation vessel is drawn to the pollution prevention frame, and FIG. 2B shows a state in which the soil transportation vessel is drawn to the pollution prevention frame. FIG. 2C shows the state of the soil carrier and the pollution prevention frame when the dredged soil is loaded in the soil carrier 3. In the illustrated example, the dredger 1 is arranged on the arrow Y2 side, but it is omitted for the sake of explanation.

The pollution prevention structure used for the dredging work of the present invention includes a movable pulley portion 70 provided on the port side 31 (hereinafter, also simply referred to as a side surface 31) of the earthmoving ship 3 and a constant pulley provided on the pollution prevention frame 2. It is provided with a portion 80, a winding device 90 provided on the dredger 1, and a towing member K for pulling the earth transporter 3 to the dredger 1 side and the pollution control frame 2 side.

The movable pulley unit 70 includes a pulley 71, a shaft 72, a connecting member 73, and a slide plate 74. The pulley 71 is configured to be rotatable by a shaft 72. Further, the pulley 71 has a V-shaped or U-shaped groove on the circumferential side surface 71a, and is configured to be capable of supporting a traction member K described later in the groove. The shaft 72 is arranged at a position parallel to the longitudinal direction of the side surface 31 of the earthmoving ship 3, and the groove of the circumferential side surface 71a of the pulley 71 is arranged along the vertical direction (arrow Z1-Z2 direction).

The connecting member 73 is a pair of left and right columns that connect the shaft 72 and the slide plate 74. The pair of connecting members 73 stand upright in a direction orthogonal to the upper surface of the slide plate 74, and are connected to both end portions of a shaft 72 that penetrates the center of the pulley 71. Therefore, the pulley 71 is rotatably arranged between the pair of connecting members 73.

The slide plate 74 is a substantially rectangular plate formed wider than the width of the pair of connecting members 73.

The slide plate 74 is arranged so as to be movable in the vertical direction (the arrow Z1-Z2 direction) between the pair of left and right guide rails 76 attached to the side surface 31 of the earthmoving ship 3. The pair of left and right guide rails 76 are arranged on the side surface 31 such that the rail direction is the vertical direction.

The pair of left and right guide rails 76 form a rail portion 77 by facing the two L-shaped angle members 76R and 76L with a constant space therebetween. A slide plate 74 is arranged on the rail portion 77, and the slide plate 74 slides in the rail portion 77.

The width between the angle members 76R and 76L is designed to be slightly wider than the width of the pair of connecting members 73 of the moving pulley unit 70, and the pulley 71 is formed so as to be vertically movable between the angle members 76R and 76L.

Therefore, since the slide plate 74 is arranged in the rail portions 77 of the pair of guide rails 76, the movable pulley portion 70 can move in the vertical direction along the guide rails 76.

Fall prevention plates 78 are attached to the bottoms of the pair of left and right guide rails 76 to prevent the moving pulley portion 70 from falling off. In addition, the upper edge portions of the pair of left and right guide rails 76 are opened, and the movable pulley portion 70 can be attached and detached. The guide rail 76 may be configured not only by an angle member as shown in the drawing, but also by facing two C-shaped steels or two H-shaped steels with a certain space therebetween.

The constant pulley section 80 has a pulley 81, a shaft 82, and a support member 83. The pulley 81 is rotatably attached to the upper surface of the float body 21 of the pollution prevention frame 2 by a shaft 82 and an L-shaped support member 83. Further, the pulley 81 has a V-shaped or U-shaped groove on the circumferential side surface 81a, and is configured to be able to support a traction member K described later in the groove. The shaft 82 is arranged at a position orthogonal to the upper surface of the float body 21 so that the groove of the circumferential side surface 81a of the pulley 81 is parallel to the upper surface of the float body 21. Therefore, the direction of the groove on the circumferential side surface 81a of the pulley 81 and the direction of the groove on the circumferential side surface 71a of the pulley 71 intersect in the orthogonal direction.

The constant pulley portion 80 of the present embodiment is provided on the side 21R of the float body 21 on the side of the earth carrier 3 (arrow X1 side). In the illustrated example, the constant pulley portion 80 is provided only on one side (side 21R) on the arrow X1 side, but may also be provided on the opposite side 21L on the X2 side. Then, it is possible to deal with whether the earthmoving ship 3 comes to the side 21R side or the side 21L side. Although the movable pulley unit 70 and the constant pulley unit 80 in the illustrated example are provided at two locations, respectively, they may be provided at one location or at multiple locations.

The movable pulley unit 70 is not limited to the one shown in the figure, and a semi-circular arc shaped piece may be used instead of the pulley 71, and the piece and the slide plate 74 may be connected. At that time, the pulling member K is implemented in such a manner that it is passed through the piece. Also in the constant pulley section 80, a semi-circular arc shaped piece may be attached to the upper surface of the float body 21 instead of the pulley 81. Further, the groove on the circumferential side surface 71a of the pulley 71 can be implemented even if it is not along the vertical direction. At that time, the connecting member 73 may be configured to rotate the pulley 71 by 360° like a snatch block. In this case, it is possible to easily pull the movable sheave portion 70 and the constant sheave portion 80 without arranging them on the X1-X2 axis when the ship 3 is anchored.

Further, it is preferable that the support member 83 of the constant pulley portion 80 has a height adjusting mechanism capable of adjusting the height in the vertical direction, and the height of the pulley 81 can be adjusted.

The winding device 90 is a winch. The winding device 90 of the present embodiment can use one or both of the existing winches provided on both sides of the dredger 1 in the width direction. Of course, a winch having an auto tension function may be used. In this embodiment, an example in which only one winding device 90 is used will be described.

The tow member K is a cord material, and may be a rope made of metal or resin. The pulling member K of this embodiment is preferably configured by connecting a plurality of cord members. However, it is also possible to use a single cord material.

The pulling member K includes a rope K1 having a base end connected to the winding device 90, and a rope K2 having a base end connected to the support 9 provided on the one side edge portion 32 of the earthmoving ship 3. have. The rope K2 is hung on the pulley 71 of the moving pulley portion 70 and the pulley 81 of the constant pulley portion 80.

A ring-shaped eye portion K1a that can be connected to other members is formed at the tip of the cord K1. A ring-shaped eye portion K2a that can be connected to other members is formed at the proximal end of the cord K2, and an eye portion K2b is formed at the distal end.

The eye portion K2b of the rope K2 may be hung on the support body 9 in the same manner as the eye portion K2a at the base end when the earthmoving ship 3 is not in close proximity to the pollution prevention frame 2. When the soil carrier 3 is moved to the pollution prevention frame 2, the eye portion K2b of the rope K2 is connected to the eye portion K1a at the tip of the rope K1 via the pulley 71 and the pulley 81 and the connecting material J such as a shackle. Then, the traction member K is formed.

With the above configuration, the traction member K, one end of which is connected to the soil carrier 3, is connected to the winding device 90. By winding the traction member K by the winding operation of the winding device 90, soil The ship 3 can be drawn to the pollution prevention frame 2.

That is, as shown in FIG. 2A, when the earthmoving ship 3 approaches, the eye portion K2b of the rope K2 is connected to the eye portion K1a of the rope K1 by the connecting material J. Then, the winding device 90 can pull up the soil carrier 3 to the pollution prevention frame 2 by winding up the tow member K connected as shown in FIG. 2B.

In addition, even if the earthmoving ship 3 sinks downward when dredged soil is loaded (arrow Z2 side), the movable pulley portion 70 moves upward along the rail portion 77 of the guide rail 76 as shown in FIG. 2C. It is possible to slide and follow the sinking of the earthmoving ship 3. At that time, the winding operation by the winding device 90 is appropriately performed, so that the clearance between the soil carrier 3 and the pollution prevention frame 2 is held constant.

In the illustrated example, the movable pulley portion 70 and the constant pulley portion 80 are provided at two places on the left and right, and the cord K2 is arranged at each of them. Both the right and left cords K2 are integrally connected to the cord K1 by the connecting member J. That is, even if there are a plurality of ropes K2 having one end connected to the earthmoving ship 3, the connection material J can be connected to the rope K1 connected to the winding device 90.

Therefore, the work of connecting the pulling member K to the winding device 90 can be simplified. Further, since the winding device 90 actually winds only one line of the line K1, even if there are a plurality of lines K2, the winding device 90 can stably attract the soil carrier 3. It can be carried out.

In addition, the winding force of the winding device 90 can minimize the gap between the pollution prevention frame 2 and the soil carrier 3, and the soil or muddy water may fall into the gap to cause pollution. It can be prevented. It is preferable that the gap between the pollution prevention frame 2 and the soil transportation ship 3 is covered with a pollution prevention sheet 8 described later.

Next, the pollution prevention sheet 8 will be described.
The pollution prevention structure used for the dredging work of the present invention includes a pollution prevention sheet 8 that hangs from one side edge portion 32 of the earthmoving ship 3 into the pollution prevention frame 2.

An upper side 8A of the pollution prevention sheet 8 is fixed on the one side edge portion 32 of the earthmoving ship 3. A weight member 8C is attached to the free lower side 8B which is not fixed. The pollution prevention sheet 8 having the above configuration is suspended between the soil carrier 3 and the pollution prevention frame 2 by hanging the lower side 8B into the pollution prevention frame 2.

As shown in FIG. 2A, the pollution prevention sheet 8 may be folded or otherwise arranged on the one side edge 32 before the soil ship 3 is drawn to the pollution prevention frame 2. Further, the lower side 8B may be arranged on the one side edge portion 32 by winding the lower side 8B around the axis.

Of course, when the work is not performed, the pollution prevention sheet 8 is removed from the one side edge portion 32 and stored in a separately prepared storage box or the like, and the pollution prevention sheet 8 is placed on the one side edge portion 32 during the work as described above. You may install it.

Then, as shown in FIG. 2B, when the soil ship 3 is pulled up to the pollution prevention frame 2 by the winding device 90, the lower side 8B of the pollution prevention sheet 8 is hung down inside the pollution prevention frame 2 and the pollution prevention sheet 8 is soiled. It is bridged between the ship 3 and the pollution control frame 2. Note that arrows G1 and G2 shown in FIG. 2B indicate movement lines of the grab bucket 61. That is, the pollution prevention sheet 8 is arranged at a position directly below the movement line of the grab bucket 61 that holds the dredged soil.

Therefore, the pollution prevention sheet 8 can catch the fallen object and return it to the pollution prevention frame 2 even if earth and sand or muddy water is dropped while the grab bucket 61 is moving on the movement line. Moreover, the pollution prevention sheet 8 can prevent falling objects from riding on the float 21 of the pollution prevention frame 2 and later falling into the surrounding water area to pollute the surrounding water area.

As described above, the pollution prevention structure used in the dredging work of the present invention is configured to draw the earth carrier 3 closely to the pollution prevention frame 2 by the winding operation of the pulling member K by the winding device 90. The pulling function and the pollution prevention function can be reliably demonstrated.

Further, the pollution prevention structure used for the dredging work of the present invention is configured to include the pollution prevention sheet 8 that hangs down from the one side edge portion 32 of the earth transportation ship 3 into the pollution prevention frame 2. Therefore, even if there is a gap between the pollution prevention frame 2 and the soil transportation vessel 3 when the soil transportation vessel 3 is drawn to the pollution prevention frame 2 by the winding device 90, the contamination prevention sheet 8 can be used to remove the gap. Can be covered. Then, even if earth and sand or muddy water is dropped while the grab bucket 61 is moving on the movement line, the pollution prevention sheet 8 receives the fallen object and returns it into the pollution prevention frame 2. It can be surely prevented that water drops and pollution occurs.

Further, in the pollution prevention structure used for the dredging work of the present invention, the movable pulley section 70 and the pollution prevention sheet 8 are installed on the soil carrier 3, the fixed pulley section 80 is installed on the pollution prevention frame 2, and the winding device 90 is installed. Was configured to use an existing winch. Therefore, since it has a simple structure, it is highly versatile. Not only that, since the moving pulley portion 70, the constant pulley portion 80, and the pollution prevention sheet 8 are relatively inexpensive, the float body 21 which may cause the soil ship 3 to come alongside the constant pulley portion 80. Can be installed on both sides (arrows X1 side and X2 side), and the movable pulley portion 70 and the pollution prevention sheet 8 can be positively installed on both sides (on both end edges) of the earthmoving ship 3. Then, the effect of the present invention can be expected regardless of whether the earthmoving ship 3 is ported to the left or right of the dredging ship 1 (arrow X1 side and X2 side), and the operation management of the earthmoving ship 3 is facilitated.

<Construction procedure>
Next, a procedure for constructing the pollution prevention structure used for the dredging work according to the embodiment of the present invention will be described with reference to FIG.

First, as shown in FIG. 3A, the earthmoving ship 3 is guided to the location of the dredger 1 by the auxiliary ship 100. At this time, the pollution prevention sheet 8 is installed in a state of being accommodated on the one side edge portion 32 of the earthmoving ship 3. Further, the eye portion K2b, which is the tip of the cord K2 fixed to the earth-moving ship 3, may be hung on the support body 9 similarly to the eye portion K2a at the base end. At this time, the cord K2 is preferably in a state of being hung on the pulley 71. In addition, a push boat or the like may be used to guide the earth transporter 3 and the dredging boat 1.

As shown in FIG. 3B, when the earthmoving ship 3 docks on the right side of the dredging ship 1 (arrow X1 side), the earthing ship 3 is moored to the port side of the dredging ship 1 by ropes 5 and the like. The dredger 1 and the pollution control frame 2 are arranged side by side. At this time, the pollution prevention frame 2 is located on the bow side (arrow Y2 side) of the earthmoving ship 3.

After that, the auxiliary ship 100 pushes the bow side of the earth transportation ship 3 so that the side surface 31 on the bow side of the earth transportation ship 3 approaches the pollution prevention frame 2.

At that time, the eye portion K2b of the rope K2 fixed to the earthmoving ship 3 is removed from the support body 9. Then, the tip end of the rope K2 is passed through the pulley 81. After that, the eye portion K2b of the cord K2 is connected to the eye portion K1a at the tip of the cord K1 by the connecting material J (see FIG. 2A).

Next, the winding device 90 winds up the tow member K by the winding operation, and draws the soil carrier 3 to the pollution prevention frame 2.

After that, as shown in FIG. 3C, the pollution prevention sheet 8 is spread, and the lower side 8B of the pollution prevention sheet 8 is hung in the pollution prevention frame 2 (see FIG. 2B).

Then, the dredging ship 1 carries out the dredging work by the lifting machine 6 in a state where the earth transporting ship 3 and the pollution prevention frame 2 are attracted. That is, the lifting machine 6 dredges the earth and sand in the pollution prevention frame 2 with the grab bucket 61. Then, the lifting machine 6 lifts the grab bucket 61 that holds the dredged sand, and then turns the main body 60 of the lifting machine 6 so that the grab bucket 61 is on the earth carrier 3, and opens the grab bucket 61. Put the earth and sand into the earth carrier 3. After that, the lifting machine 6 turns the main body 60 to dispose the grab bucket 61 on the pollution prevention frame 2. The dredging work is performed by repeating the above operation.

During the dredging work, the gap between the pollution prevention frame 2 and the soil carrier 3 is completely eliminated by the pollution prevention sheet 8 as described above, so that soil and muddy water may fall into the gap to cause pollution. Can be reliably prevented. Further, when the grab bucket 61 is moving on the moving lines G1-G2, even if earth and sand or muddy water is dropped, the pollution prevention sheet 8 receives the fallen object and returns it to the pollution prevention frame 2, so that the fallen object The risk of pollution can be prevented.

Although the preferred embodiments of the present invention have been described above in detail, the present invention is not limited to the above specific embodiments, and various modifications are possible within the scope of the gist of the present invention described in the claims. It can be modified and changed.

For example, a wire may be connected to both ends of the lower side 8B of the pollution prevention sheet 8 in the illustrated example. One end of the wire is fixed to the support 9 on the one edge 32 of the earthmoving ship 3. Therefore, the pollution prevention sheet 8 can be pulled up by pulling up the wire rod.

1 Dredger 2 Pollution Prevention Frame 21 Float 21R Side (right side of float)
21L side (left side of float body)
22 Contamination prevention film 3 Earth transport ship 31 Side surface 32 One side edge part 4, 5 Rope 6 Lifter 60 Main body 61 Grab bucket 62 Boom 63 Wire 70 Moving pulley part 71 Pulley 72 Shaft 73 Connecting material 74 Slide plate 76 Guide rail 77 Rail Part 78 Fall prevention plate 8 Contamination prevention sheet 8A Upper side 8B Lower side 8C Weight material 80 Constant pulley part 81 Pulley 82 Shaft 83 Support material 9 Support body 90 Winding device 100 Auxiliary vessel K Traction member J Connecting material

Claims (5)

A pollution prevention frame arranged in front of the dredging ship, and an earth transportation ship , which is arranged on the port side of the dredging ship and is arranged in parallel with the dredging ship and the pollution prevention frame, and on which the dredged sand is loaded. It has a structure to prevent pollution of dredging work,
A movable pulley portion that is movable in the vertical direction along a guide rail provided at a position facing the pollution prevention frame on the port side of the earth- moving ship,
A constant pulley portion provided at a position facing the movable pulley portion on the soil carrier side of the pollution prevention frame,
A winding device provided on the dredger,
A towing member for pulling the earth-moving ship to the dredging ship side and the pollution prevention frame side;
Is equipped with
The traction member has a rear end connected to the winding device, an intermediate part is hung on the moving pulley part and the constant pulley part, and a tip end is connected to the earth transporter ,
The connecting portion of the towing member with the earth transporter is located above the moving pulley portion,
The movable pulley portion is arranged so as to change the extending direction of the pulling member extending downward from the connecting portion to a direction toward the constant pulley portion,
The constant pulley unit is arranged to change the extending direction of the pulling member extending from the moving pulley unit to a direction toward the winding device provided in the dredger arranged behind the pollution prevention frame.
A pollution prevention structure used for dredging work. The movable pulley portion is
The pollution prevention structure used for dredging work according to claim 1 , wherein the structure is detachable from the guide rail. The pollution prevention structure used for dredging work according to claim 1, wherein the pulling member is a cord material. The traction member is
The pollution prevention structure used for dredging work according to claim 3 , wherein a plurality of the cord members are connected to each other. The earth carrier has
The upper side is fixed to one side edge of the earth transporter, and the lower side is provided with a pollution prevention sheet that hangs down into the pollution prevention frame. Used for dredging work according to claim 1. Pollution prevention structure.

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