JP2002275932A - Dredging method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dredging method which improves dredging efficiency when dredging depth is deepened without hindering marine navigation of traveling ships. SOLUTION: According to the method, a dredging regions A out of a plurality of continuously arranged dredging regions A, B, C is enclosed by one of contamination preventive screens 4, and bottom materials in the contamination preventive screen 4 is excavated and removed, followed by collecting earth and sand 41 in a lower layer of the bottom materials 40. Then, the dredging region A is enclosed by the other contamination preventive screen, and then the bottom materials 40 are backfilled into the other contamination preventive screen. In this manner, a series of the above steps are repeatedly carried out, to thereby execute the dredging.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dredging method for dredging rivers and ports, and more particularly to a dredging method capable of preventing the spread of polluted water in water.

[0002]

2. Description of the Related Art Generally, in a highly closed bay area, a large amount of sludge accumulates along with an increase in the population of the bay area and activation of industrial activities, so that the navigation of large vessels is not hindered. It is necessary to dredge the bay. In addition, although the sludge dredged is transported on land and disposed of as industrial waste, the number and area of this disposal site tend to decrease due to environmental regulations, and it is difficult to dispose of it. It is the current situation.

As a conventional dredging method, for example, there is a method disclosed in Japanese Patent Application Laid-Open No. 10-112448. In this dredging method, a plurality of caissons are adjacent to each other, excavation and removal of the topsoil in a certain caisson, and sediment under the topsoil are collected, and then excavation of the topsoil in another caisson, and By backfilling and collecting sediment in other caisson, it is not necessary to dispose of unnecessary topsoil.

Another conventional dredging method is disclosed in Japanese Patent Application Laid-Open No. 7-229162. In this dredging method, the dredging area is surrounded by a water-impervious pollution prevention frame, and the contaminated water in the pollution prevention frame is pumped up and filtered.
The water is discharged outside the pollution prevention frame, and the bottom of the dredging area is excavated and dredged while introducing non-polluted water outside the pollution prevention frame into the pollution prevention frame.

[0005]

However, in the former conventional example, since a plurality of caisson, which is a temporary structure, is required, when the dredging area hits the navigation channel, there is an obstacle to the navigation of passing vessels. There is a problem of coming. Also,
In this conventional example, since the earth and sand between the inner plate of the caisson and the cutting edge cannot be excavated, a step occurs on the earth and sand surface after the excavation, and the surface becomes uneven. Therefore, when the depth is deeper than the top surface of the earth and sand, it is necessary to excavate while overlapping the dredging area, which causes a decrease in work efficiency, lacks the stability of the caisson, and also poses a problem that the excavation work becomes difficult .

On the other hand, in the latter conventional example, since the excavated earth and sand is classified and washed on land, noise and vibration problems due to these operations occur, and the drainage of the washing water used for the washing operation occurs. There is a problem that water pollution tends to occur. Also, in this conventional example, earth and sand that cannot be reused for concrete aggregate, etc.
There is also a problem that industrial waste must be treated as a by-product of construction, and disposal sites and disposal costs increase.

Therefore, the present invention has been made in view of the above circumstances, and does not hinder the navigation of passing vessels.
It is an object of the present invention to provide a dredging method that improves work efficiency when increasing the depth.

[0008] Another object of the present invention is as follows.
It is an object of the present invention to provide a dredging method that can reduce noise and vibration caused by a classification operation and a cleaning operation, and is less likely to generate water pollution.

[0009]

According to a first aspect of the present invention, a dredging area is surrounded by a pollution prevention curtain, and the inside of the pollution prevention membrane is excavated. In the dredging method of excavating while sequentially moving
After excavating and removing the sediment in the pollution prevention curtain, the lower layer of the sediment is collected, and the dredging area where the sediment is collected is
The method is characterized in that a dredging method is performed in which a series of steps for backfilling with the sediment is sequentially repeated to perform dredging.

According to a second aspect of the present invention, a certain dredging area in a plurality of continuously provided dredging areas is surrounded by one pollution control curtain, and the sediment in the pollution control curtain is excavated and removed. The dredging method is characterized in that a series of steps for sequentially collecting the soil and sand, enclosing the dredging area with the other pollution prevention curtain, and filling the sediment in the pollution prevention curtain, and performing dredging, are performed.

According to a third aspect of the present invention, a certain dredging area in a plurality of continuously provided dredging areas is surrounded by one pollution prevention curtain, and the sediment in the pollution prevention curtain is excavated and removed. Of the clay and sand and gravel in order, the dredging area was surrounded by the other pollution control curtain, and a series of steps of backfilling the sediment and the clay in the pollution control curtain in this order was repeated to perform dredging. It is characterized by the following.

The invention described in claim 4 is the first to third aspects of the present invention.
In addition to the configuration according to any one of the above, the collected earth and sand is classified and washed in the dredging area.

[0013] The invention according to claim 5 is the invention according to claims 1 to 4.
In addition to the configuration according to any one of the above, the wastewater obtained by washing the earth and sand is discharged into the pollution prevention curtain.

[0014]

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

[First Embodiment of the Invention] FIGS. 1 to 7 show a first embodiment of the present invention.

First, the structure will be described. As shown in FIGS. 1 to 6, in front of the dredger 1, dredging areas A, B,
While the C is sequentially connected, a grab 2 is mounted on the upper front of the dredger 1, and the grab 2 controls a grab bucket 3 for excavating the dredging areas A, B, and C so as to be able to move horizontally and vertically. I do.

The dredger 1 has dredging areas A, B, and C.
(A dredging area A in FIGS. 1 to 4), and a water-blocking anti-pollution curtain 4 for preventing the diffusion of contamination in water is fixed. The anti-pollution curtain 4 is composed of dredging areas A, B, and C. When it is set in a rectangular shape, it has a flat rectangular tube shape, and a square frame-shaped float 5 is fixed to the upper opening edge, while a weight 6 is fixed to the lower end.

Further, a barge 7 is fixed to the side surface of the dredger 1, and the barge 7 has a mud cell 8 capable of storing excavated sediment.
A bottom door 9 is attached to the bottom of the mud cell 8 so as to be openable and closable, and by opening the bottom door 9, the sediment stored in the mud cell 8 is drawn into the dredging areas A, B, C can be discharged. The barge 7 is fixed to the tug 11 via the wire 10. Therefore, the barge 7 can be moved in the X-Y directions by the movement of the tug 11, and
With the movement of the barge 7, the dredger 1 can also move.

On the other hand, when the excavated soil is to be treated, the dredging vessel 1 is provided with a dredged soil processing barge 15 as shown in FIG. The sediment hopper 16 for loading the gravel and the earth and sand in the dredging areas A, B and C excavated in 3, the reciprocating feeder 17 for conveying the gravel and the earth and sand loaded on the sediment hopper 16, and the reciprocating feeder 17 And a trommel 18 for performing classification and washing of the gravel and soil and water.

The trommel 18 has a water supply pipe 19
The other end of the water supply pipe 19 extends to the outside of the dredged soil processing barge 15 and is connected to a water pump 20.

Gravel and earth and sand in the dredging areas A, B, and C are classified and washed by the trommel 18 to form aggregate for ready-mixed concrete. The aggregate is loaded on the barge 8 by the belt conveyor 21, and Other aggregates are supplied to the aggregate grinder 24, the vibrating sieve 25 and the cyclone 26 by the belt conveyor 22, and these aggregate grinders 24,
Classified and washed by the vibrating sieve 25 and the cyclone 26, and loaded on the barge 8 by the belt conveyor 23.

Further, below the cyclone 26, a spillage collecting tank 28 for collecting spillage such as washing of gravel and earth and sand is installed.
One end of a drain pipe 30 is connected to the drain pump 29. A cushion pipe is provided at the other end of the drain pipe 30 near the end of the dredged soil treatment barge 15 to prevent damage due to waves. 31 is inserted, and the other end of the other end extends into the float 5 of the pollution prevention curtain 4.

The driving source of each of the above devices is a generator 3
2, power is supplied from the control panel 2 and the control panel and the wiring system are not shown.

Next, the dredging method of this embodiment will be described.

The dredging method according to the present embodiment comprises a "sediment excavation step", a "gravel and earth and sand excavation step", and a "sediment backfill step". First, the "sediment excavation step" will be described.

As shown in FIGS. 1 and 2, the dredging area A on the front surface of the dredging vessel 1 is surrounded by a pollution control curtain 4, and the pollution control curtain 4 is fixed to the dredging vessel 1. Then, the pollution prevention curtain 4 is made independent underwater, and the pollution prevention curtain 4 prevents the diffusion of the pollution generated by underwater excavation.

Next, the sediment (organic silt, etc.) 40 from the existing sediment surface F1 to the existing sediment surface F2 of the dredging area A is excavated by the grab bucket 3, and the excavated sediment 40 is fixed to the side surface of the dredger 1. It is loaded into the mud cell 8 of the barge 7.

Here, in order to load the excavated sediment 40 evenly in the mud storage 8, the towing boat 11 is moved in the XY direction, and the barge 7 is moved in the XY direction.

Further, the bottom 40 of the dredging area A is excavated to a predetermined depth (in the present embodiment, the existing earth and sand surface F2).

Next, the dredger 1 is moved in the X direction, and the existing sediment surface F1 and the existing sediment surface F
The excavated sediment 40 is excavated, and the excavated sediment 40 is loaded into the mud cell 8 of the barge 7 fixed to the side surface of the dredger 1. Hereinafter, the dredging area is moved from B to C, and the area to be dredged is excavated by the same method as described above.

The excavated sediment 40 is transported on land and treated by a method similar to the conventional method, or temporarily placed on a barge at sea and used for backfilling.

The excavated sediment 40 is back-filled on the flooring surface F3 by a “back-filling step” to be described later to replace the topsoil.

Next, the "gravel and earth and sand excavation process" will be described.

As shown in FIGS. 3 and 4, after the dredger 1 is placed in the dredging area A in which the sediment 40 has been excavated, the gravel and the sand 41 from the existing soil surface F2 to the floor surface F3 are removed by the grab bucket 3. The excavated gravels and the earth and sand 41 are loaded into the earth and sand hopper 16 of the dredged earth and sand processing barge 15 which is excavated and fixed to the side surface of the dredger 1.

Next, the gravel and the earth and sand 41 are classified and washed on the dredged soil processing barge 15, the processed aggregate is loaded, and loaded into the mud storage 8 of the barge 7 by the belt conveyor 23. The gravel and the earth and sand 41 in the dredging area A are excavated to a predetermined depth (in the present embodiment, the floor surface F3).

Further, the dredger 1 is moved to the dredging area B in the X direction, and the existing soil surface F2 of the dredging area B is moved in the same manner as described above.
And the sand 41 from the ground to the flooring surface F3 are excavated by the grab bucket 3, and the excavated sand and the sand 41 are loaded into the earth and sand hopper 16 of the dredged soil processing barge 15 fixed to the side surface of the dredger 1, and the sand and the sand 41 are loaded. Classify 41
The washed and processed aggregate is loaded, and the belt conveyor 23
To the mud cell 8 of the barge 7.

Hereinafter, the dredger 1 is moved to the dredging area C, and the area to be dredged is excavated in the same manner as described above.
The classified and washed gravel and earth and sand 41 are transported on land by the dredged soil treatment barge 15 and recycled as valuable resources such as ready-mixed concrete aggregates, while cobblestones and the like that are not suitable as aggregates are used as beach nourishment materials. Reuse.

Further, the "submerged substance backfilling step" will be described.

After the excavation to the floor-attached surface F3 is completed, a barge 7 loaded with the sediment 40 excavated in the sediment excavation step described above is installed in the dredging area A by the tugboat 11, as shown in FIGS.

Next, a pollution prevention curtain 4a is hung around the barge 7 to prevent the diffusion of pollution in water. A weight 6a is fixed to a lower end of the pollution prevention curtain 4a.

Further, the bottom door 9 of the barge 7 is opened, and the barge 7 is opened.
The sediment 40 loaded on the bottom surface is sequentially backfilled on the floor-attached surface F3, and the topsoil is replaced while securing the depth H necessary for dredging to the bottom material backfill surface F4.

Thereafter, the above steps are repeated while moving the barge 7 in the X direction, and dredging and replacement of the sediment 40 are performed. If the bottom sediment backfilling surface F4 obtained by dredging and replacing the bottom sediment 40 in this way is uneven (uneven), a long steel material (not shown) is lowered to the finishing surface, and Leveling unevenness by pulling steel.

As described above, according to the present embodiment, the underwater pollution caused by excavation is performed by the pollution prevention curtain 4 fixed to the barge 7, so that the installation and movement of the pollution prevention curtain 4 can be performed in a short time. A temporary structure such as a caisson is not required, so that navigation of the ship is not hindered, and it is easy to increase the depth to a position deeper than the surface of the earth and sand without having to worry about excavating the cutting edge of the adjacent caisson. be able to.

Further, since the sludge of the sediment 40 is replaced with excavated gravel and earth and sand 41 to increase the depth, the generation of industrial waste of sludge can be greatly reduced. And, since the replacement is performed in the dredging area, the moving distance of the sludge is short, the leakage of the sludge when transporting and transporting to land is small, and the pollution of water quality can be reduced.

Further, since the dredging areas A, B, and C can be continuously dredged, work efficiency can be improved.

Further, the collected gravel and soil 4
1 is classified and washed in the dredging areas A, B, and C, so that noise and vibration caused by the classification and washing operations can be reduced.

Further, the waste water from which the gravel and the earth and sand 41 have been washed is discharged into the pollution prevention curtain 4 so that the occurrence of water pollution of the waste water due to the washing can be prevented. The aggregate after classification and washing can be used as aggregate for ready-mixed concrete and beach nourishment material, so that industrial waste can be reduced.

[Second Embodiment of the Invention] FIGS. 8 and 9
Shows a second embodiment of the present invention.

Since the structure is the same as that of the first embodiment, the same reference numerals are given and the description is omitted.

In the present embodiment, a case where the dredged ground is an alternately-layered ground such as organic silt, clay 42, and gravel 43 as the sediment 40 will be described.

The dredging method according to the present embodiment will be described.

The dredging method of the present embodiment comprises a “sediment excavation step”, a “gravel and earth and sand excavation step”, and a “sediment backfilling step” as in the first embodiment. Similar to the “bottom excavation process” in mode 1, the bottom 40
Drilling.

After that, the clay 42 and the gravel 43 in the alternation ground under the sediment 40 are excavated, and the excavated alternation ground is excavated in the same manner as the “gravel and sediment excavation process” in the first embodiment. Classify and wash. Here, aggregate and the like are recycled and reused in the same manner as in the first embodiment, while clay 42 that cannot be recycled is loaded on the barge 7.

Next, the dredging and replacement of the sediment 40 in the “sediment backfilling step” in the first embodiment is performed in the dredging area A where the clay 4 is backfilled to the sediment backfilling surface F4.
A barge 7 loaded with 2 is placed by a tugboat 11.

Further, a pollution prevention curtain 4a is suspended around the barge 7 in order to prevent the diffusion of pollution in water. A weight 6a is fixed to a lower end of the pollution prevention curtain 4a.

Next, the bottom door 9 of the barge 7 is opened, and the clay 42 loaded on the barge 7 is sequentially backfilled from the bottom sediment backfilling surface F4 to the cover soil dredging surface F5, and the sediment 40 is removed. Clay 42
And secure the required depth H for dredging.

Thereafter, the above steps are repeated while moving the barge 7 in the X direction, and the soil is covered with the clay 42 and dredging is performed. In addition,
When the finish of the covered soil dredging surface F5 is uneven,
A long steel material (not shown) is lowered to the finishing surface, and the steel material is pulled by the tugboat 11, thereby leveling unevenness.

As described above, according to the present embodiment, the clay 42 that cannot be reused is buried in the dredging areas A, B, and C, so that the cost of waste disposal and the disposal site can be reduced. In addition, by covering the sediment 40 with the clay 42, the sludge of the sediment 40 does not diffuse,
The occurrence of water pollution can be prevented.

The present invention is not limited to the above embodiments, and various changes can be made. For example, in each of the above embodiments, an example in which dredging is performed by using a grab has been described.
Even when a land machine such as a back four is mounted on the top, construction is possible similarly.

Further, in the second embodiment, the soil 40 is covered with the clay 42. Alternatively, the soil 40 may be covered with the gravel 43.

[0061]

As described above, according to the invention described in each claim, after excavating and removing the sediment in the pollution control curtain,
Since the lower layer of the sediment was sampled and the dredging area where the sediment was collected was filled with the sediment to repeat the series of steps to perform dredging, the installation and movement of the pollution prevention curtain was short. It takes time and eliminates the need for temporary structures such as caissons, does not hinder the navigation of ships, and does not require excavation while overlapping dredging areas. Without deepening, it is possible to easily increase the depth to a position deeper than the surface of the earth and sand. In addition, backfilling of sediment can reduce waste disposal costs and disposal sites.

According to the third aspect of the present invention, a certain dredging area in a plurality of continuously provided dredging areas is surrounded by one pollution control curtain, and after excavating and removing the sediment in the pollution control curtain,
Clay and sand and gravel in the lower layer of the sediment are sampled in order, the dredging area is surrounded by the other pollution control curtain, and a series of steps of backfilling the sediment and the clay in the pollution control curtain in order are sequentially repeated for dredging. By doing so, the cost of waste disposal and the disposal site can be reduced, and the sludge of bottom sediment does not spread, thereby preventing the occurrence of water pollution.

According to the fourth aspect of the present invention, the collected earth and sand is classified and washed in the dredging area, so that noise and vibration caused by the classification and washing operations can be reduced.

According to the fifth aspect of the present invention, the wastewater from which the sediment has been washed is discharged into the pollution prevention curtain,
It is possible to prevent the occurrence of water pollution of wastewater due to washing.

[Brief description of the drawings]

FIG. 1 is a side view showing a sediment excavation step according to Embodiment 1 of the present invention.

FIG. 2 is a plan view of FIG. 1;

FIG. 3 is a side view showing a sand and gravel excavation process according to the first embodiment of the present invention.

FIG. 4 is a plan view of FIG. 3;

FIG. 5 is a side view showing a sediment backfilling step according to the first embodiment of the present invention.

FIG. 6 is a plan view of FIG. 5;

FIG. 7 is a plan view showing a dredged sediment processing barge according to the first embodiment of the present invention.

FIG. 8 is a side view showing a clay covering step in Embodiment 2 of the present invention.

9 is a configuration diagram showing a cross section taken along line AA of FIG. 8;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dredge 2 Grab 3 Grab bucket 4 Pollution prevention curtain (one pollution prevention curtain) 4a Pollution prevention curtain (the other pollution prevention curtain) 5 Float 6 Weight 7 Barge 8 Mud storage 9 Bottom door 10 Wire 11 Towing boat 15 Dredging soil treatment Barge 40 Sediment 41 Gravel and sediment 42 Clay 43 Gravel A, B, C Dredging area F1 Existing sediment surface F2 Existing sediment surface F3 Floor surface F4 Sediment backfill surface H Deepening

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hiromi Miya 1-24-4 Shinkawa, Chuo-ku, Tokyo Daitoyo Construction Co., Ltd. F term (reference) 2D025 AA02

Claims (5)

[Claims] 1. A dredging method wherein a dredging area is surrounded by a pollution control curtain, the inside of the pollution control membrane is excavated, and excavation is performed while sequentially moving the pollution control membrane. After that, the lower layer of sediment was collected, and the dredged area where the
A dredging method characterized by sequentially performing a series of steps of backfilling with sediment to perform dredging. 2. A dredging area in a plurality of continuously provided dredging areas is surrounded by one pollution prevention curtain, and sediment in the pollution prevention curtain is excavated and removed. A dredging method, wherein a dredging area is surrounded by the other pollution control curtain, and a series of steps for backfilling the sediment in the pollution control curtain is sequentially repeated to perform dredging. 3. A dredging area in a plurality of continuously provided dredging areas is surrounded by one pollution control curtain, and the sediment in the pollution control curtain is excavated and removed. A dredging method comprising: surrounding the dredging area with the other pollution prevention curtain, and performing a series of steps of backfilling the sediment and the clay in this pollution prevention curtain in order, thereby performing dredging. 4. The method according to claim 1, wherein the collected sediment is classified and washed in the dredging area.
The dredging method according to any one of claims 1 to 3. 5. The dredging method according to claim 1, wherein the wastewater from which the soil is washed is discharged into the pollution prevention curtain.