JP2002266369A - Construction method and device for dredging - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance dredging efficiency not only by making drainage, which is brought about by separating dredged sediment and water, jetted in a dredged part so as to blow up the sediment but also by making the drainage jetted reversely near a suction port for the dredged sediment so as to produce an ejection effect, and decrease as much pollution of a dredged sea area as possible by circulating the drainage without discharging the drainage on a sea bottom. SOLUTION: The sediment accumulated on the sea bottom is dredged by a suction pump 11. The dredged sediment and water are separated by a separating means 15, and the drainage brought about by separation is made to flow back by a drainage pump 17. The drainage made to flow back is pressurized by a booster pump 12 and jetted from a jet nozzle 26 near the dredged part in order to blow up the accumulated sediment. The drainage is jetted reversely from an ejection nozzle 24 provided at the center of a wrapper tube 20, so as to enhance a suction effect.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for dredging soil and the like deposited on the bottom of a sea (port), river, lake or dam lake (hereinafter referred to as the sea bottom) by suction.

[0002]

2. Description of the Related Art In a method of dredging (suctioning) soil and the like deposited on the seabed by a suction pump, seawater (hereinafter, referred to as seawater) is used.
The slurry, which is dredged together with water (water), is separated into sediment and water, the sediment is further classified, and the separated water is returned to the sea.

[0003] Separation of earth and sand from water involves solidifying the earth and sand into a cake using a filter press or the like.
Slurry (mixed of earth and sand and water) is introduced into a sedimentation basin, and a sedimentation accelerator is added for sedimentation. Some are separated into earth and sand and water by cyclone method.

[0004] In addition, the water after solid / liquid separation has returned to the sea, but simply refluxing would pollute the construction target sea area. By the way, it is also proposed to discharge (Japanese Patent Laid-Open No. 01-3)
No. 22030).

In Japanese Patent Application Laid-Open No. 2000-355253,
A method has been proposed in which separated drainage is guided to a dredging section and jetted toward the dredging section.

[0006]

In the above separation method,
Since it is hardened into a cake, subsequent processing is difficult, and it is practically impossible to classify and recycle by particle size. There is a concern that chemical harm may occur.If the particle size of the dredged soil is within a certain range, the desired effect can be obtained, but if the particle size is distributed over a wide range, classification is practical. It is not an exaggeration to say that it is impossible to implement the system from the viewpoint of the maintenance and maintenance of the device due to severe damage to the device.

Further, since the separated water is guided deeply into the seabed and refluxed as proposed in Japanese Patent Application Laid-Open No. 01-322030, the polluted sea area expands over time, although it has a certain effect, and it is not sufficiently satisfactory. Was.

Further, in the proposal of Japanese Patent Application Laid-Open No. 2000-355253, drainage is recirculated and ejected to the dredging part, so that it is possible to expect a slight improvement in dredging efficiency. It has problems such as the spread and the blown-up sediment not being captured sufficiently.

In view of the above-mentioned prior art, the present invention provides an ejecting effect by ejecting drainage obtained by separating dredged soil and water from a dredging section to blow up the earth and sand, and in reverse jetting near a suction port of the dredged earth and sand. It is an object of the present invention to provide a method and an apparatus for improving dredging efficiency by reducing the pollution of a dredged sea area as much as possible by circulating drainage without discharging it to the sea floor.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a method of dredging sediment deposited on the bottom of the sea, river, lake, or dam lake together with water by suction means. In the dredging method in which water is separated and the separated wastewater is returned to the dredging part via a pressurizing pump and a return pipe, a method in which the drainage is ejected in the vicinity of the suction port of the suction means, As an apparatus for carrying out this method, means for separating dredged earth and water into earth and water, means for pressurizing and refluxing the separated wastewater toward the dredging part, A dredging device comprising a flapper tube to be ejected, wherein the wrapper tube is provided with an ejector nozzle and a jet nozzle.

According to the present invention configured as described above,
Drained water after the dredged sediment / water is separated is used as a jet stream for dredging and circulates while increasing the operation of the suction pump by reverse jetting, minimizing pollution in the dredged sea area. In addition, it has the effect of enhancing the dredging effect.

[0012]

Next, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, a dredge vessel 10 is provided with a suction pump 11 and a pressurizing pump 12 for drainage. A suction pipe 13 extends from a suction port of the suction pump 11 to a dredging section G on the seabed, and a trumpet pipe 20 is attached to an end thereof. And a discharge pipe 14 from the discharge port of the suction pump 11.
And is opened by sediment / water separation means 15 (including classification means) provided on the opposite shore.

On the opposite shore, a drain tank 16 and a drain pump 17 are installed following the sediment / water separating means 15, and a drain pipe 18 extends from the discharge port of the drain pump 17 toward the dredger 10 and is provided on the dredger 10. A reflux pipe 19 is connected to the pressure pump 12 and extends from a discharge port of the pressure pump.
Is connected to

As shown in FIG. 2, a protective net 21 is attached to the front of the opening of the wrapper tube 20, and a short tube 2 is provided at the rear.
2, a suction tube 13 (see FIG. 1) is connected.

The end of the reflux pipe 19 extending from the pressurizing pump 12 on the dredger 10 is bisected, and one end is connected to an ejector nozzle 24 which is connected to an ejector pipe 23 and is attached to the center of the wrapper pipe 20 in the opposite direction. The other is provided with four jet nozzles 26 via an annular pipe 25 (see FIG. 3).
Is connected to

The ejector tube 23, the reflux tube 19, and the short tube 22 are fixed at a predetermined interval from each other by a bracket 27a, and the jet nozzle 26 and the trumpet tube are fixed to each other by a bracket 27b and a U-bolt 28. .

In the above embodiment, the sediment / water separating means, the drainage tank and the drainage pump are provided on the opposite shore, but they may be provided on the dredger, and in this case, the drainage pump may be omitted.

Next, the operation of the present invention will be described. In the description, it is assumed that a certain amount of drainage is stored in the drainage tank.

When the operation of the suction pump 11, the drain pump 17 and the pressurizing pump 12 is started, the drain water is ejected from the jet nozzle 26 toward the dredging section G to blow up the earth and sand of the dredging section G, and at the same time the suction pump 11 The sediment is sucked together with the seawater by the suction force, and at this time, the drainage spouts in the opposite direction from the eject nozzle 24 attached to the center of the wrapper pipe 20 in the opposite direction, assisting the suction force of the suction pump 11 and efficiently dredging. Done.

The sediment / water discharged from the suction pump 11 is separated into sediment and water by a sediment / water separating means 15 via a discharge pipe 14, and the wastewater is stored in a drainage tank 16, and the sediment is subjected to a classifier to a predetermined size. Classified into particle sizes. A known classifier can be used as proposed by the applicant in Japanese Patent Application No. 10-79520.

[0021]

As described above, according to the present invention,
When the seabed sediment is sucked together with the seawater by the suction pump, the drainage squirts into the dredging part and blows up the sediment to assist the dredging, and at the center of the wrapper pipe, the drainage spouts by the eject nozzle to assist the suction force. As well as exerting the dredging effect beyond the function of the suction pump,
The drainage circulates between the drainage system and the drainage system as described above, and it becomes possible to minimize the pollution of the dredged sea area.

[Brief description of the drawings]

FIG. 1 is a diagram of a dredging system according to the present invention.

FIG. 2 is a detailed view of a wrapper tube portion employed in the present invention.

FIG. 3 is a left side view of the trumpet tube.

FIG. 4 is a view taken in the direction of arrows AA in FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Dredge ship 11 Suction pump 12 Pressure pump 13 Suction pipe 14 Drain pipe 15 Sediment / water separation means 16 Drain tank 17 Drain pump 18 Drain pipe 19 Reflux pipe 20 Wrapper pipe 21 Protection net 22 Short pipe 23 Ejector pipe 24 Eject nozzle 25 Ring Pipe 26 Jet nozzle 27a, 27b Bracket 28 U bolt

Claims (5)

[Claims] Claims: 1. A sediment deposited on the bottom of a sea, river, lake, or dam lake is dredged together with water by suction means, and the dredged sediment / water is separated. A dredging method, wherein the drainage water is reversely ejected in the vicinity of a suction port of the suction means, in a dredging method for refluxing in a dredging section via a reflux pipe. 2. The dredging method according to claim 1, wherein a part of the drainage returned through the pressurizing pump and the return pipe is jetted toward a dredging part. 3. The dredging method according to claim 1, wherein the separated earth and sand is charged into a classification means to classify the sediment. 4. Means for separating the dredged soil and water into earth and sand, means for pressurizing and refluxing the separated wastewater toward the dredging unit, and a wrapper pipe for jetting the pressurized and refluxed wastewater. A dredging device comprising: an ejector nozzle and a jet nozzle in the wrapper tube. 5. The dredging apparatus according to claim 4, wherein said sediment / water separation means is provided with earth and sand classification means.