JP2004197351A - Method of dredging sediment from bottom of water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple, inexpensive and efficient method of dredging sediment from the bottom of water, which hardly interferes with environment and the navigation of ships. <P>SOLUTION: A deep water delivery pipe 1A is provided under the sea above the sea bottom surface 20 in a target water area, and for example a deep water delivery pump 3 for supplying deep water with a density greater than that of water near the surface 20 is connected to the pipe 1A. These emit a jet of the deep water in a direction almost parallel to the surface 20, generate a sea bottom surface sweeping water flow 14A which runs in such a manner as to sweep the top of the surface 20, remove settled sediment particles 16 by carrying away and discharging the particles 16 in the state of riding the particles 16 on the water flow 14A, and prevent the accumulation of the particles 16 on the surface 20. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a submarine sediment removal method for removing sedimentary sediment in order to prevent sedimentary sediment from accumulating on the surface of the submarine water.
[0002]
[Prior art]
If sediment accumulates near the bottom of the sea, river, lake, etc., the water depth of the navigation channel and the basin will be shallow, which will hinder the use of ships. For this reason, when the water depth of the navigation channel or the basin becomes shallower than a predetermined value, the sediment near the water bottom is dug or scooped, transported to another place, discarded, or diverted to a material such as landfill. “Dredge”, which is an operation, is performed (for example, see Patent Document 1).
[0003]
As one of the methods of such dredging work, water is blown out and sprayed on sediment near the water bottom to generate a water flow (hereinafter, referred to as a “jet water flow”), and the jet water flow causes the sediment to be deposited on the water floor. There is a known method of excavating the soil and removing the sediment in the target water area by transporting the excavated earth and sand to the flow of the jet water stream and transporting it to other places. Have a proven track record.
[0004]
On the other hand, in Japan, when the water bottom is a hard sandy soil or a bedrock, etc., as a pre-treatment process for performing dredging, the water bottom ground is crushed using the above-mentioned jet stream, and thereafter, a pump-type dredger, or There is an example in which a construction method of performing a dredging operation using a grab dredger or the like has been adopted. With a pump dredger, a suction pipe is connected to a pump loaded on the hull, the pump is operated after the suction pipe is lowered to the bottom of the water, and the soil at the bottom of the water is mixed with nearby water from the suction port of the suction pipe It is a dredger of the type that sucks up in the state. The grab type dredger is a dredger of a type in which a grab bucket is mounted on a hull, the grab bucket is lowered to the bottom of the water, and sediment on the bottom of the water is grasped by the grab bucket.
[0005]
[Patent Document 1]
JP-A-2002-143894 (pages 1-4, FIG. 1)
[0006]
[Problems to be solved by the invention]
However, the above-mentioned dredging work using the jet stream has the following problems.
[0007]
(I) In the case of a dredging operation directly using a jet water flow, since sediment at the bottom of the water is rolled up and disturbed, and a great deal of pollution is generated in the water at the dredging work site, there is an environmental problem. In addition, even when the jet water flow is used as a pre-dredge work and the dredging work itself is a construction method using a pump-type dredger or a grab-type dredger, it is unavoidable to generate pollution in the water at the dredging work site.
[0008]
(Ii) In the construction method using jet water flow, a work pump equipped with a hull equipped with a delivery pump for applying pressure to water and sending it out, and a water squirt pipe that descends to the bottom of the water, moves on the water surface while spraying the jet water flow on the bottom sediment. Often done. For this reason, when the construction surface occupies the water surface of the construction site and dredging work is carried out on the existing channel or berth, it becomes a major obstacle for the navigating ship.
[0009]
(Iii) Even when the dredging is performed as described above, since the earth and sand move from the peripheral part due to the water flow, etc., after a certain time has elapsed after the dredging, the earth and sand may be deposited again near the water bottom. Many. For this reason, the dredging work needs to be performed repeatedly, but the dredging work is a large-scale work and requires a great deal of labor and construction cost. Therefore, repeating the dredging work many times does not save the labor and cost spent.
[0010]
The present invention has been made in order to solve the above problems, and an object of the present invention is to provide a simple, low-cost, and efficient method of removing sediment from underwater with less hindrance to the environment and ship navigation. Is to provide.
[0011]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the method for removing underwater sediment according to claim 1 of the present invention comprises:
In the vicinity of the surface of the bottom of the target water area, a spout is provided, and high-density water supply means for supplying high-density water, which is water having a density higher than the density of water near the bottom, to the spout, is provided at the spout. connection,
The high-density water flow is generated by ejecting the high-density water in a direction substantially parallel to the water bottom surface by the high-density water supply means and the jet port, so that the high-density water flows so as to sweep over the water bottom surface. A subsurface sweep water flow is generated, and the submerged sediment is removed by placing and discharging sedimentary sediment, which is sediment that sinks from the vicinity of the water surface of the target water area toward the water bottom, on the subsurface sweep water flow, and the sedimentation is removed. It is characterized in that sediment is prevented from accumulating on the water bottom surface.
[0012]
Further, the method of removing sediment according to claim 2 of the present invention increases the speed of the jet of the high-density water from the jet port, and removes the sediment already deposited near the water bottom. The deposited sediment is removed by placing the deposited sediment on the bottom surface sweeping water flow and discharging the sediment sequentially from the upper layer.
[0013]
Further, in the method for removing underwater sediment according to claim 3 of the present invention, after the waterproof sheet is laid in advance above the surface of the water bottom, the waterproof sheet is supplied by the high-density water supply means and the jet port. By ejecting the high-density water in a direction that is substantially parallel to the surface of the surface, the effect of the bottom surface sweeping water stream sweeping the settled sediment is increased.
[0014]
Further, in the undersea sediment removal method according to claim 4 of the present invention, the high-density water is used by pumping deep water, which is water at a deep position deeper than near the water bottom.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0016]
(1) First embodiment
FIG. 1 is a conceptual diagram illustrating the contents of a seabed sediment removal method according to a first embodiment of the present invention. As shown in FIG. 1, in the seabed sediment removal method of the first embodiment, a deep water delivery pipe 1A, a deep water delivery pump (not shown), a connection pipe (not shown), and a deep water pumping pump ( (Not shown), a deep water pumping pipe (not shown), and a device provided with a control unit (not shown).
[0017]
The above-mentioned deep water delivery pipe 1A is installed in seawater above a surface (hereinafter, referred to as “sea bottom”) 20 of a water area (hereinafter, referred to as “target water area”) to be subjected to soil removal. I have. The lower part of the deep water delivery pipe 1A is supported by a support member (not shown) that stands upright from the sea floor 20. Further, the deep water delivery pipe 1A is a tubular member having both ends opened, arranged so that the longitudinal direction thereof is substantially parallel to the sea bottom 20, and an ejection port having an opening at the tip (right end in FIG. 1). 2A.
[0018]
The rear end (left end in FIG. 1) of the deep water delivery pipe 1A is connected to a deep water delivery pump (not shown). Further, one end of a connection pipe (not shown), which is a tubular member, is connected to the deep water delivery pump, and a deep water pumping pump (not shown) is connected to the other end of the connection pipe. . The deep water pump (not shown) is connected to the deep water pump.
[0019]
The deep water pumping pipe is a tubular member having both ends opened, and its longitudinal direction is arranged so as to be substantially vertically up and down or inclined, and the deep water pumping port (opening) is provided at its tip (lower end). (Not shown). The deep water pumping port is installed at a position where the water depth is deeper than the sea bottom 20, for example, at a position where the water depth is about 50 meters or more deeper than the position of the sea bottom 20 (hereinafter referred to as “deep position”). The control unit (not shown) has a computer and the like, and is electrically connected to the deep water delivery pump and the deep water pumping pump by a conducting wire or the like, and controls these.
[0020]
In FIG. 1, reference numeral 15 denotes the sea surface, reference numeral 16 denotes sediment particles settling from the sea surface to the sea floor (hereinafter, referred to as “settling sediment particles”), and reference numeral 17 denotes sediment deposited on the sea floor. Is shown.
[0021]
Next, the procedure of the seabed sediment removal method of the first embodiment will be described.
[0022]
First, the control unit outputs an operation command signal to the deep water pump and the deep water delivery pump. As a result, the deep water pump starts operating, and pumps seawater (hereinafter referred to as “deep water”) from the deep position. Generally, the seawater at a deep position has a lower water temperature than the seawater in the upper layer (for example, the seawater near the sea bottom 20). Seawater is pure water (H _Two O), sodium chloride (NaCl), and other salts. Pure water (H _Two O) has a maximum density at 3.98 ° C. at 1 atm. Thus, from room temperature to 3.98 ° C., the lower the temperature, the higher the density of water. For this reason, the density of deep water is higher than that of seawater near the sea bottom 20.
[0023]
The deep water pumped by the deep water pump is sent to the deep water delivery pump through the connecting pipe. The deep water delivery pump applies pressure to the deep water sent from the connection pipe and sends it to the deep water delivery pipe 1A. The deep water 13 delivered from the deep water delivery pump is ejected from the ejection port 2A into nearby seawater.
[0024]
In this case, the deep water delivery pipe 1A is disposed so that its longitudinal direction is substantially parallel to the sea bottom 20, and its tip (the right end in FIG. 1) is an opening 2A, which is an opening. The deep water jetted from 2A flows substantially parallel to the sea bottom 20, that is, along the sea bottom 20, as indicated by reference numeral 14A in FIG. Further, the deep water has a higher density than the seawater near the sea bottom 20, and has the same weight as the seawater near the sea bottom 20 when having the same volume. Therefore, the flow 14 </ b> A of the deep water flows while sinking toward the sea bottom 20. For this reason, the flow 14A of deep water becomes a flow of water as if it were sweeping, dragging, stroking, or sweeping over the sea floor 20. Hereinafter, such a flow 14A of deep water is referred to as a “sea bottom sweeping water flow”.
[0025]
By the above-mentioned sea bottom sweeping water flow 14A, the top of the sea bottom 20 is always swept away. For this reason, the sedimentary sediment particles 16 that have settled from the sea surface 15 to the sea bottom 20 are swept away by the sea bottom sweeping water flow 14A and become a deep water / sediment mixture 18 mixed with the deep sea water, and the sea bottom sweep is performed. It is carried on the water flow 14A, flows as a mixed flow 19 in the direction of the sea bottom sweeping water flow 14A, that is, in the direction from left to right in FIG. 1, and is discharged to the outside of the target water area. As a result, the sedimentary sediment particles 16 are constantly removed from the sea bottom 20, so that the sedimentation sediment particles 16 are reliably prevented from accumulating on the sea bottom 20.
[0026]
The above-described apparatus of the seabed sediment removal method of the first embodiment can perform other operations. That is, the control unit 7 outputs a pressure increase command signal to the deep water delivery pump. Thereby, the deep water delivery pump further increases the pressure applied to the deep water. Accordingly, the ejection speed of the deep water 13 ejected from the ejection port 2A further increases. For this reason, the strength of the sea bottom sweeping water flow 14A sweeping over the sea bottom 20 increases, and the sediment 17 (hereinafter, referred to as “pre-deposited sediment”) 17 that has already been deposited near the sea bottom 20 is increased. Sequentially from the upper part, swept by the sea bottom sweeping water flow 14A, the sediment deposited 17 is put on the sea bottom sweeping water flow 14A, and mixed in the direction of the sea bottom sweeping water flow 14A, that is, in the direction from left to right in FIG. It is washed off as stream 19 and discharged out of the target water area. Thus, the sediment 17 is sequentially removed from its upper layer.
[0027]
The above seabed sediment removal method has the following advantages.
[0028]
(A) The deep water of the main stream of the sea bottom sweeping water flow 14A flows only above the sea bottom 20 in the target water area, and part of the deep sea water of the sea bottom sweeping water flow 14A gradually flows to the sea bottom 20 due to the difference in density. And the lowest deep water flows so as to lightly sweep over the sea floor 20. Also, the density of the mixed flow of deep water and earth and sand is larger than the density of the surrounding seawater, so that the mixed flow rarely diffuses near the water surface and flows almost along the sea bottom 20. Therefore, the occurrence of water pollution in seawater in the target water area can be minimized as compared with the conventional construction method in which the jet water stream is directly blown onto the sea bottom surface 20.
[0029]
(B) When the sea bottom 20 has irregularities, the sea bottom sweeping water flow 14A cuts off the protrusions on the sea bottom 20, and the shaved soil fills the recesses on the sea bottom 20, As a whole, a “leveling action” may be exhibited in which the sea floor 20 of the target water area becomes smooth.
[0030]
(C) Of the above-mentioned devices, at least the deep water delivery pipe 1A is merely installed in the seawater above the sea floor 20 in the target water area, so that the influence on the ship navigation can be minimized.
[0031]
(D) Since it is only necessary to eject the deep water 13 from the ejection port 2A, the effect of preventing sediment accumulation and the effect of removing sediment in the target water area can be exerted continuously or as needed.
[0032]
(E) At first, among the above-mentioned devices, it is necessary to install at least the deep water delivery pipe 1A, the deep water delivery pump, and the connection pipe in seawater above the sea bottom 20 in the target water area. Other than that, no special labor or equipment is required, the cost is lower than that of conventional dredging, and less labor is required.
[0033]
(2) Second embodiment
The present invention can be realized by configurations other than the above. Next, a second embodiment of the present invention will be described. FIG. 2 is a conceptual diagram illustrating the contents of a seabed sediment removal method according to a second embodiment of the present invention. As shown in FIG. 2, the seabed sediment removal method of the second embodiment is different from the seabed sediment removal method of the first embodiment described above in that a waterproof sheet 8 is laid beforehand above the seabed 20. The configuration and operation of the other elements are the same as in the first embodiment.
[0034]
As a material of the waterproof sheet 8, a thin film member, a sheet member, or the like made of a synthetic resin material or a rubber material can be used. The synthetic resin-based material and the rubber-based material include a single synthetic resin material, a rubber material, and a fiber-reinforced plastics (FRP) in which carbon fiber, glass fiber, synthetic resin fiber, and the like are embedded. ) Etc. are also included.
[0035]
In the seabed sediment removal method of the second embodiment, after laying the waterproof sheet 8 above the seabed 20 in advance, the jetting of the deep water delivery pipe 1A is performed using an apparatus having the same configuration as that of the first embodiment. Deep water 13 is ejected from the outlet 2A in a direction substantially parallel to the upper surface of the waterproof sheet 8. In this case, the waterproof sheet 8 blocks the seabed 20 from the deposited sediment 17. For this reason, the sedimentary sediment particles 16 swept away by the sea bottom sweeping water flow 14A cannot sink into the already deposited sediment 17 and are unilaterally swept away. Therefore, the effect of sweeping the settled earth and sand particles 16 by the sea bottom sweeping water stream 14A and preventing the sedimentation thereof is greater than in the first embodiment.
[0036]
(3) Third embodiment
The present invention can be realized by configurations other than the above. Next, a third embodiment of the present invention will be described. FIG. 3 is a conceptual diagram illustrating the contents of a seabed sediment removal method according to a third embodiment of the present invention. As shown in FIG. 3, the seabed sediment removal method of the third embodiment is different from the seabed sediment removal method of the first embodiment described above in the vicinity of the target water area ZC indicated by the broken line in FIG. This is a point in which two deep water delivery pipes 1C1 and 1C2 are provided, a plurality of ejection ports 2C1 and 2C2 are provided in each of the deep water delivery pipes, and a direction in which each of the ejection ports 2C1 and 2C2 faces is set to a predetermined direction. The configuration and operation of the other elements are the same as in the first embodiment.
[0037]
That is, in the third embodiment, in the target water area ZC, the direction in which the earth and sand are to be discharged (hereinafter, referred to as “soil and sand discharge direction”). In this case, the direction from left to right in FIG. 3 is the longitudinal direction. In this manner, the two deep water delivery pipes 1C1 and 1C2 are installed in the seawater above the sea bottom so as to sandwich the target water area ZC from both sides so as not to hinder the navigation of the ship.
[0038]
The deep water delivery pipe 1C1 is provided with a plurality of jet ports 2C1. In addition, the direction in which each jet port 2C1 faces is the direction in which the jet proceeds in the sediment discharging direction while heading toward the center of the target water area ZC, in this case, the oblique direction from the upper left to the lower right in FIG. 3 is unified. I have. On the other hand, the deep water delivery pipe 1C2 is provided with a plurality of ejection ports 2C2, and the direction of each ejection port 2C2 is the direction in which the water advances in the sediment discharging direction while facing the center of the target water area ZC. Are unified in an oblique direction from the lower left to the upper right in FIG.
[0039]
Further, although not shown, the deep water delivery pipes 1C1 and 1C2 have a deep water delivery pump having the same configuration and operation as in the first embodiment, a connection pipe, and a deep water pumping pump, respectively. , A deep water pumping pipe and a control unit are installed in the same connection configuration as in the first embodiment.
[0040]
With such a configuration, when the deep water is jetted from each of the jet ports 2C1, 2C2, the sea bottom sweeping water flows 14C1, 14C2 are generated, whereby the sea bottom in the target water area ZC is discharged in the sediment discharging direction (FIG. 3). (In the direction from left to right in FIG. 3). For this reason, the settled sediment particles that have settled from the sea surface to the sea floor are swept by the sea bottom sweep water flow that is the merging of the sea bottom sweep water flows 14C1 and 14C2, and the sediment is loaded on the sea bottom sweep water flow. 3, and is discharged to the outside of the target water area ZC to be removed. As a result, sedimentation of the sedimentary sediment particles on the sea bottom of the target water area ZC is reliably prevented.
[0041]
Further, as in the case of the first embodiment, by increasing the strength of the sea bottom sweeping water currents 14C1 and 14C2 to sweep over the sea bottom, the sediment already deposited near the sea bottom is Sequentially from the upper part, the sea bottom sweeping water currents 14C1 and 14C2 are swept by the combined sea bottom sweeping water flow, and the sediment is deposited on the combined sea bottom sweeping water flow, and from left to right in FIG. And is discharged outside the target water area ZC. As a result, the sediment deposited in the target water area ZC is sequentially removed from its upper layer.
[0042]
In addition, flaky members (not shown) that move by the water flow are arranged at the ejection ports 2C1 and 2C2, and the flaky water members move by the jet of the deep water, whereby the deep water is moved. You may comprise so that the ejection direction may change suitably. In this case, since the direction in which the deep water is ejected is not always the same, the sea bottom sweeping water flows 14C1 and 14C2 sweep the sea bottom in the target water area ZC without bias. For this reason, it is prevented that earth and sand stay at a place in the target water area ZC.
[0043]
(4) Fourth embodiment
The present invention can be realized by configurations other than the above. Next, a fourth embodiment of the present invention will be described. FIG. 4 is a conceptual diagram illustrating the contents of a seabed sediment removal method according to a fourth embodiment of the present invention. As shown in FIG. 4, the seabed sediment removal method of the fourth embodiment is different from the seabed sediment removal method of the first embodiment described above in the vicinity of the center of the target water area ZD indicated by the broken line in FIG. A point in which a single deep water delivery pipe 1D is provided, a plurality of ejection ports 2D1 and 2D2 are provided in the deep water delivery pipe 1D, and the direction in which each of the ejection ports 2D1 and 2D2 faces is aligned with a predetermined direction. The configuration and operation of the other elements are the same as in the first embodiment.
[0044]
That is, in the fourth embodiment, in the target water area ZD, the center line of the target water area ZD is set to be in the longitudinal direction, and the target water area ZD is immersed in seawater at an appropriate depth position in the target water area ZD so as not to hinder navigation of the ship. One deep water delivery pipe 1D is installed in seawater above the sea floor.
[0045]
Further, the deep water delivery pipe 1D is provided with a plurality of outlets 2D1 and a plurality of other outlets 2D2. Further, the direction in which each jet port 2D1 faces is one of the directions in which the earth and sand are to be discharged (hereinafter, referred to as “first earth and sand discharging direction”). In this case, the direction is from the lower left to the upper right in FIG. It is unified in the diagonal direction. In addition, the direction in which each ejection port 2D2 faces is another direction in which the earth and sand are to be discharged (hereinafter, referred to as a “second earth and sand discharge direction”). In this case, the direction is oblique from the upper left to the lower right in FIG. The direction is unified.
[0046]
Although not shown, the deep water delivery pipe 1D includes a deep water delivery pump having the same configuration and operation as in the first embodiment, a connection pipe, a deep water pump, and a deep water pump. The pipe and the control unit are installed in the same connection configuration as in the first embodiment.
[0047]
With such a configuration, when the deep water is jetted from each of the jet ports 2D1 and 2D2, the sea bottom sweeping water currents 14D1 and 14D2 are generated, and thereby, the sea level of the target water area ZD is higher than the center line in FIG. The area is always swept away in the first earth and sand discharge direction (the oblique direction from the lower left to the upper right in FIG. 4), and the area below the center line in FIG. 4 on the sea bottom of the target water area ZD is the second earth and sand. It is in a state of being constantly swept in the discharge direction (oblique direction from upper left to lower right in FIG. 4). Therefore, the settled sediment particles that have settled from the sea surface to the sea bottom are swept by the sea bottom sweeping water flows 14D1 and 14D2 in the direction toward the water flow, and the sediment is loaded on the sea bottom sweeping water flows 14D1 and 14D2. And is discharged to the outside of the target water area ZD and removed. As a result, sedimentation of the sedimentary sediment particles on the sea bottom of the target water area ZD is reliably prevented.
[0048]
Further, as in the case of the first embodiment, by increasing the strength of the sea bottom sweeping water flows 14D1 and 14D2 to sweep over the sea bottom, the sediment already deposited near the sea bottom is Sequentially from the upper part thereof, they are swept by the sea bottom sweeping water flows 14D1 and 14D2, and the sediment deposited is carried on the sea bottom sweeping water flows 14D1 and 14D2, flows in the direction of the water flow, and is discharged out of the target water area ZD. You. Thus, the sediment deposited in the target water area ZD is sequentially removed from its upper layer.
[0049]
In addition, flaky members (not shown) that move by the water flow are arranged at the ejection ports 2D1 and 2D2, and the flaky water moves so that the flaky members move by the jet of the deep water, whereby the deep water is moved. You may comprise so that the ejection direction may change suitably. In this case, since the direction of ejection of deep water is not always the same, the sea bottom sweeping water flows 14D1 and 14D2 sweep the sea bottom in the target water area ZD without bias. For this reason, it is prevented that earth and sand accumulate at places in the target water area ZD.
[0050]
(5) Fifth embodiment
The present invention can be realized by configurations other than the above. Next, a fifth embodiment of the present invention will be described. FIG. 5 is a conceptual diagram illustrating the content of a seabed sediment removal method according to a fifth embodiment of the present invention. As shown in FIG. 5, the seabed sediment removal method of the fifth embodiment differs from the seabed sediment removal method of the first embodiment described above in that the deep water delivery pipe 1E configured to be movable in seawater. Is moved within the area of the target water area ZE indicated by the broken line in FIG. 5, and the configuration and operation of the other elements are the same as those in the first embodiment.
[0051]
That is, in the fifth embodiment, the traction wires 10a and 10b are attached to the deep water delivery pipe 1E, and the vicinity of the end of the traction wire 10b is connected to traction means (not shown) such as a winch. Further, in the target water area ZE, the substantially center line of the target water area ZD is set to be in the longitudinal direction of the traction wire 10b, and the deep water delivery pipe 1E and the traction wires 10a, 10b are connected to the target water area ZD so as not to hinder the navigation of the ship. Arrange so that the seawater is at an appropriate depth.
[0052]
Further, a plurality of ejection ports 2E are provided in the deep water delivery pipe 1E, and one end of the deep water delivery pipe 1E is closed, and one end of a water supply hose 9 is connected to the other end of the deep water delivery pipe 1E. Further, the direction in which each jet port 2E is directed is a direction in which earth and sand are to be discharged (hereinafter, referred to as a “sand discharge direction”), in this case, a direction from left to right in FIG.
[0053]
Although not shown, the other end of the water supply hose 9 has a deep water delivery pump having the same configuration and operation as in the first embodiment, a connection pipe, a deep water pumping pump, and a deep water pump. The riser pipe and the control unit are installed in the same connection configuration as in the first embodiment.
[0054]
With such a configuration, when deep water is jetted from each of the jet ports 2E, a sea bottom sweeping water flow 14E is generated. In this state, when the tow wire 10b is wound in a direction from left to right in FIG. The water delivery pipe 1E moves in a direction from left to right in FIG. Thereby, the sea bottom sweeping water flow 14E moves from left to right in FIG. 5 while sweeping on the sea bottom of the target water area ZE. Therefore, the target water area ZE is constantly swept away in the earth and sand discharge direction (the direction from left to right in FIG. 5). Therefore, the settled sediment particles that have settled from the sea surface to the sea bottom are swept in the direction of the water flow by the moving sea bottom sweeping water flow 14E, and the sediment is loaded on the moving sea bottom sweeping water flow 14E. It is washed away and discharged outside the target water area ZE and removed. Thereby, the sedimentary sediment particles are surely prevented from accumulating on the sea bottom of the target water area ZE.
[0055]
In addition, as in the case of the first embodiment, by increasing the intensity of the moving sea bottom sweeping water flow 14E sweeping over the sea bottom, the sediment that has already been deposited near the sea bottom, From the upper part thereof, it is swept by the moving sea bottom sweeping water flow 14E sequentially, and the deposited sediment is carried on the moving sea bottom sweeping water flow 14E, flows in the direction of the water flow, and is discharged out of the target water area ZE. You. Thereby, the sediment deposited in the target water area ZE is sequentially removed from its upper layer.
[0056]
In addition, a flaky member (not shown) which moves by the water flow is disposed at the jet port 2E, and the flaky water moves by the blast of the deep water, whereby the jetting direction of the deep water is obtained. May be appropriately changed. In this case, since the direction of ejection of the deep water is not always the same, the sea bottom sweeping water flow 14E sweeps the sea bottom of the target water area ZE without bias. Therefore, it is possible to prevent the earth and sand from staying at a place in the target water area ZE.
[0057]
In the fifth embodiment described above, when hindrance to ship navigation in the target water area ZE does not pose a significant problem, a winch is used to connect the vicinity of the end of the tow wire 10b to tow the tow wire 10b. Instead, a work boat (not shown) that sails on the sea surface or in seawater may be used. In this case, the deep water delivery pump, the connection pipe, the deep water pumping pump, and the control unit having the same configuration and operation as those of the first embodiment are mounted on this work boat, and You may comprise so that a deep water pumping pipe may be descended toward a deep position in the sea.
[0058]
In each of the above embodiments, the sea bottom surface 20 corresponds to the water bottom surface in the claims, and the deep water corresponds to the high-density water in the claims. An apparatus including the deep water delivery pipes 1A to 1E, a deep water delivery pump, a connection pipe, a deep water pumping pump, a pumping pipe, and a control unit constitutes a high-density water supply unit in the claims. Further, the sea bottom sweeping water flows 14A to 14E correspond to the sea bottom sweeping water flow in the claims.
[0059]
Note that the present invention is not limited to the above embodiments. Each of the above embodiments is an example, and has substantially the same configuration as the technical idea described in the scope of the claims of the present invention, and any device having the same operation and effect can be obtained. It is included in the technical scope of the present invention.
[0060]
For example, in each of the above embodiments, an example was described in which a jet port (2A or the like) and a high-density water supply means (1A or the like) are provided in seawater above the sea bottom, but the present invention is not limited to this. Even if the jet port and the high-density water supply means are provided in another location, for example, in the bottom of the water slightly below the sea bottom, the effect of sweeping out the sediment in the vicinity can be exhibited. In addition, even when the jet port and the high-density water supply means are arranged near the surface of the bottom of the inland water such as a lake, a pond, a swamp, etc., the sedimentary sediment or the sedimentary sediment may be removed from the bottom of the sea. It can be transported and removed on a sweeping water stream. Therefore, the position where the jet port and the high-density water supply means are provided only needs to be near the surface of the water bottom surface.
[0061]
Further, in each of the above embodiments, an example is described in which deep water pumped from the deep sea is used as high-density water, but the present invention is not limited to this, and high-density water obtained by another method is used. Water may be used. For example, the high-density water may be generated by cooling water near the bottom of the target water area by cooling means (not shown; for example, a cooling device having a known heat exchanger or the like). Pure water has a maximum density at 3.98 ° C. at 1 atm. Therefore, from room temperature to 3.98 ° C., the density of pure water increases as the temperature decreases. For this reason, if the water near the water bottom in the target water area is cooled by the cooling means, the water can have higher density than the water near the water bottom in the target water area.
[0062]
Alternatively, in the case of seawater, the concentration of salt may be increased by concentrating the seawater to increase the density. For example, once the salt in seawater is extracted and separated by the ion-exchange resin method or the like, then this salt is dissolved in less water than before, or water is evaporated by heating the seawater once to evaporate the water. And the like can be considered. However, it is necessary to consider the biological environment of the target water area when cooling water or increasing the salt concentration.
[0063]
Further, three or more deep water delivery pipes may be provided. Further, the control unit has a timer (not shown) configured by hardware or software, and is configured to operate the deep water pumping pump and the deep water sending pump every predetermined period (for example, every month). You may. Further, the deep water delivery pump may be configured to double as the deep water pump.
[0064]
In addition, when natural forces due to waves, tidal action, tidal currents, river flows, and the like can be effectively used, a driving force for pumping and sending deep water may be used. In addition, the height position of one end (the left end in FIG. 1 and the like) of the deep water delivery pipe 1A and the like is set higher than the height position of the ejection port 2A, and the deep water 13 is separated from the deep water delivery pipe 1A using gravity. For example, the driving force may be a driving force for flowing the same.
[0065]
When the natural force acts in the opposite direction so as to inhibit the ejection of deep water from the outlet 2A or the like, a non-illustrated check valve (from left to right in FIG. 1) is provided in the middle of the deep water delivery pipe 1A or the like. (A valve configured to open in the forward direction toward, and close in the reverse direction from right to left in FIG. 1) may be provided to prevent backflow.
[0066]
In addition, the design specifications of the above-mentioned apparatus (1A etc.), for example, the diameter of the deep water delivery pipe 1A etc. (or the outlet 2A etc.), the delivery pressure or water flow velocity, the direction of deep water ejection, the deep water delivery pipe 1A Regarding the installation interval and number of multiple installations, the depth position of the deep water pumping port, etc., the type of sediment (silt soil or sandy soil, etc.) in the water area (target water area) where the spout 2A is installed , Its particle size, density (specific gravity), amount of sedimentation (cm / year, etc.), topography and water depth around the target water area, such as surface currents and submarine currents in the target water area, weather conditions in the target water area, target It is necessary to design considering the water temperature of the water area, the salinity of the target water area, the impact on the environment of the target water area (existing biological environment, impact on fisheries, etc., the acceptable degree of water pollution, etc.). is there.
[0067]
Generally, when the amount of sediment deposited is small and fine silty soil with high fluidity is used, the interval between the deep water delivery pipes 1A and the like may be wide, and the diameter of the deep water delivery pipes 1A and the like may be small. In addition, since the fluidity of the earth and sand is high, it can be easily transferred and removed, and the degree of freedom in design is considered to be high.
[0068]
On the other hand, when the amount of sediment deposited is large and sandy soil with low fluidity is used, the interval between the deep water delivery pipes 1A and the like is increased, the diameter of the deep water delivery pipe 1A and the like is increased, and the delivery pressure is increased. It is also necessary to make the water flow velocity and the like large. Also, since the fluidity of the earth and sand is small, it is somewhat difficult to transfer and remove the earth and sand, and it is considered that the degree of freedom in design is reduced.
[0069]
In addition, the position of the spout 2A or the like of the deep water delivery pipe 1A or the like is alternately provided on the left and right in the advancing direction of the sea bottom sweeping water flow 14A or the like in plan view. It is necessary to take care not to be uneven, and to ensure that the earth and sand loaded on the sea bottom sweeping water flow 14A are smoothly transported.
[0070]
【The invention's effect】
As described above, according to the first to fourth aspects of the present invention, an outlet is provided near the surface of the water bottom in the target water area, and high-density water having a density higher than the density of water near the water bottom is injected. The high-density water supply means to be supplied to the outlet is connected to the spout, and the high-density water supply means and the spout eject high-density water in a direction substantially parallel to the bottom surface. Generates a bottom surface sweeping water flow, which is a flow of high-density water that flows so as to remove the sediment deposited on the bottom surface sweeping water flow and discharges it, preventing sedimentation of the sediment on the bottom surface be able to. Therefore, it has the following advantages.
[0071]
The high-density water of the main stream of the bottom-swept water flows only above the bottom surface of the water, and part of the high-density water in the swept-bottom water stream gradually sinks toward the bottom due to the density difference, High-density water flows like a light sweep over the bottom of the water. Also, the density of the mixed flow of high-density water and earth and sand is larger than the density of the surrounding water, so that the mixed flow rarely diffuses near the water surface and flows almost along the water bottom. Therefore, the occurrence of water pollution in the target water area can be minimized as compared with the conventional construction method in which the jet stream is directly blown to the water bottom.
[0072]
In addition, when the water bottom has irregularities, the above-described water bottom sweeping water stream cuts the protrusions on the water bottom, and the shaved soil fills the recesses on the water bottom, so that the water bottom as a whole is smooth. In some cases, a certain "leveling action" is exhibited.
[0073]
Since only the spout is installed in the water above the water bottom in the target water area, the influence on ship navigation can be minimized.
[0074]
Since only the high-density water needs to be spouted from the spout, the effect of preventing sediment accumulation and the effect of removing sediment can be exerted continuously or as needed.
[0075]
Initially, it is necessary to install some or all of the high-density water supply means in the water above the bottom of the target water area, but no special labor or equipment is required other than that, Lower cost and less labor than dredging.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram illustrating the contents of a seabed sediment removal method according to a first embodiment of the present invention.
FIG. 2 is a conceptual diagram illustrating the contents of a seabed sediment removal method according to a second embodiment of the present invention.
FIG. 3 is a conceptual diagram illustrating the contents of a seabed sediment removal method according to a third embodiment of the present invention.
FIG. 4 is a conceptual diagram illustrating the contents of a seabed sediment removal method according to a fourth embodiment of the present invention.
FIG. 5 is a conceptual diagram illustrating the contents of a seabed sediment removal method according to a fifth embodiment of the present invention.
[Explanation of symbols]
1A-1E Deep water delivery pipe
2A ~ 2E Spout
8 Waterproof sheet
9 Water supply hose
11a, 11b traction wire
13 Deep water
14A-14E Sea bottom sweep water flow
15 Sea level
16 Settling sediment particles
17 Deposited sediment
18 Deep water / sediment mixture
19 Mixed flow
20 Sea floor
ZC-ZE Target water area

Claims (4)

In the vicinity of the surface of the bottom of the target water area, a spout is provided, and high-density water supply means for supplying high-density water, which is water having a density higher than the density of water near the bottom, to the spout, is provided at the spout. connection,
The high-density water supply means and the jet port eject the high-density water in a direction substantially parallel to the water bottom surface, so that the high-density water flows so as to sweep over the water bottom surface. A subsurface sweep water flow is generated, and the submerged sediment is removed by placing and discharging sedimentary sediment, which is sediment that sediments from the vicinity of the water surface of the target water area toward the water bottom, on the subsurface sweep water flow, and the sedimentation is removed. An underwater sediment removal method, which prevents sediment from accumulating on the underwater surface. In the method for removing underwater sediment according to claim 1,
Increasing the speed of the high-density water jet from the jet port, and discharging the sediment, which is the sediment already deposited near the water bottom, from the upper part thereof onto the water-bottom sweeping water flow, and discharging the sediment. A method of removing submerged sediment by removing the sediment. In the method for removing underwater sediment according to claim 1,
After laying a waterproof sheet above the water bottom surface in advance, the high-density water is supplied from the high-density water supply means and the jet port in a direction substantially parallel to the surface of the waterproof sheet, thereby discharging the water bottom surface. A method for removing submarine sediment, wherein a sweeping water flow increases the effect of sweeping the settled sediment. In the method for removing underwater sediment according to claim 1,
A method of removing sediment according to claim 1, wherein said high-density water is used by pumping deep water, which is water at a deep position deeper than the water bottom.

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