JP3303169B1 - Underwater sand covering method and sediment sampling equipment - Google Patents

Abstract

An object of the present invention is to provide a method of covering sand on a water bottom and an apparatus for collecting sediment, which does not generate treated soil such as dredged soil and does not require separate preparation of sand for covering sand. SOLUTION: This method is a method of covering the bottom of a water bottom, wherein the soil deposited in the bottom of the water is fluidized and the surface layer of the bottom is covered with the sand squirted on the bottom. Further, there is provided a sediment collecting apparatus 1 for collecting sediment deposited on the underwater ground, comprising a hollow guide pipe 2 and a jet pipe 3 loaded inside the guide pipe.
By jetting a fluid from at least one of the tip and the side of the jet pipe, the earth and sand in the underwater ground rises in the gap between the guide pipe and the jet pipe and blows up from the upper end of the guide pipe. It is assumed that.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of covering the bottom of a seabed such as a lake or the sea with sand or the like for covering sludge deposited on the bottom of the sea with sand or the like, and a method of collecting sediment or the like accumulated on the bottom of a waterbed. It relates to a sampling device.

[0002]

2. Description of the Related Art Conventionally, there are a dredging method and a sand covering method as methods for maintaining good water quality and aquatic ecosystem such as lakes and seas. The dredging method is a method of exposing the lower layer of high quality soil by removing surface sludge deposited on the water floor. The sludge of the surface layer has a high elution amount, particularly a high nutrient elution amount,
The high DO (dissolved oxygen) consumption causes deterioration of water quality. Further, it is not preferable for living environment of living things. For this reason, the dredging method is a method of keeping water quality and aquatic ecosystem favorable by removing sludge which causes the dredging method. On the other hand, the sand covering method obtains the same effect as the dredging method by covering sludge deposited on the sea floor with sand or the like.

[0003]

The above-described conventional dredging method for water bottom and sand covering method have the following problems. <B> In the dredging method, it is often difficult to secure a disposal site or disposal site for dredged soil. That is, dredged sludge always raises more economical problems, both in improving sludge and in securing disposal sites and disposal sites. <B> With the sand covering method, it is difficult to obtain good quality sandy soil. In recent years, it is difficult to secure good quality sand for landfill, and even if it is available, the material cost is high. In addition, when sand is collected from other places, the environment of the sand pit is destroyed, so that a problem remains. <C> In the sand covering method, since the sand is further prepared on the surface layer to provide the sand covering layer, the water bottom becomes high. As a result, there may be problems such as a decrease in the storage capacity of the lake as a regulating pond, a hindrance to the navigation of the ship, and a destruction of the aquatic ecological environment.

[0004]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned conventional problems. In addition to the fact that no treated soil such as dredged soil is generated, it is necessary to separately prepare sand for covering sand. It is an object of the present invention to provide a method of covering sand on an underwater floor and a device for collecting sediment. It is another object of the present invention to provide a method of covering sand on a water bottom and a device for collecting sediment capable of economically and effectively maintaining water quality and aquatic ecosystem in a water area. Still another object of the present invention is to provide a method of covering the bottom of the water with a small change in the height of the bottom of the water and a device for collecting sediment. It is another object of the present invention to provide a method for covering sand on a water bottom and a device for collecting soil and sand that can effectively use the soil deposited on the bottom of the water bottom. The present invention achieves at least one of these objects.

[0005]

Means for Solving the Problems In order to achieve the above-mentioned object, a method for covering sand with a water bottom according to the present invention is to fluidize the sediment deposited inside the bottom of the water bottom, and to use the sand squirted onto the water bottom to form the bottom of the water. This is a method characterized by covering a surface layer. here,
Earth and sand means sand, earth or a mixture of sand and earth.
Preferably applied to sand or sandy soil.

The underwater sediment collecting apparatus of the present invention is a sediment collecting apparatus for collecting sediment deposited on the underwater ground, comprising a hollow guide pipe and a jet pipe loaded inside the guide pipe. By jetting a fluid from at least one of the tip and the side of the jet tube,
It is characterized in that earth and sand in the underwater ground rises in the gap between the guide pipe and the jet pipe and blows up from the upper end of the guide pipe. Here, "from at least one of the tip and the side surface of the jet tube" means that the jet hole provided in the jet tube is only the front end or the side surface; It means that the fluid can be ejected from only one side. Further, the number of injection ports provided can be arbitrarily selected. For example, four injection ports may be provided on the side surface of the jet tube.

Here, the jet tube has a multi-layer structure,
Multiple fluid paths may be provided. For example, if the jet pipe is a double pipe, there are two fluid paths, so the first path is the path of the fluid ejected from the tip, and the second path is the path of the fluid ejected from the side. Can be used. When the jet tube has a triple structure, three fluid paths can be used. Therefore, in addition to the above-described usage method, the remaining one path can be a different type of fluid path. For example, the fluid ejected from two paths may be water, and the fluid ejected from one path may be air.

Further, a truncated pyramid shape extending upward,
In addition, a guide tool may be provided that is disposed with a gap secured between the guide tube and the upper end of the guide tube.

[0009] In the method for covering sand on a bottom of the water according to the present invention, the above-mentioned apparatus for collecting sediment on the bottom of the water is inserted to a predetermined position on the bottom of the water bottom so that the upper part of the guide pipe projects from the bottom of the water. Is injected into the ground further into the ground while injecting fluid, and the sediment in the underwater ground fluidized by the injected fluid rises in the gap between the guide pipe and the jet pipe, and blows up from the upper end of the guide pipe to raise the water bottom. It is a method characterized by covering with sediment deposited inside the underwater ground.

[0010] Here, the jet tube can jet fluid while rotating to fluidize the earth and sand on the underwater ground. When the fluid is ejected from the side surface, it is effective to rotate the jet tube so that the fluid can be ejected evenly to the earth and sand around the jet tube.

Here, it is also possible to cover a wide range of water bottom by repeating at predetermined intervals in a grid pattern. In addition, it becomes possible to cover the sand in various shapes in a plane while considering the ecosystem.

[0012]

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

<A> Soil sampling device The soil sampling device 1 includes a hollow guide pipe 2 and a jet pipe 3. The jet tube 3 is loaded inside the guide tube 2 and is configured to move independently of the guide tube 2. The earth and sand sampling device 1 is a device for collecting earth and sand deposited in the underwater ground. If sediment squirted from the bottom of the water to the bottom of the water is received by a basket or the like and raised above the water surface, it can be used for soil collection. In addition, if the bottom of the water is covered with earth and sand that has erupted on the bottom without installing a basket or the like, it can be used for the sand covering method.

<B> Jet Tube The jet tube 3 is a tube material for injecting a fluid such as water or air from at least one of a tip and a side surface. The shape of the jet tube 3 used in the present invention is preferably formed in a truncated cone shape in which the injection port 31 side is widened. For example, diameter 4 ~
A steel pipe or the like in which the injection port 31 is widened by about 6 to 8 cm at about 6 cm is used (see FIG. 1). It is also possible to use a tube material whose diameter does not change up to the injection port or a tube material whose injection port 31 is narrow like a nozzle. Further, it is also possible to close the tip of the jet tube 3 and make a hole in the side surface of the jet tube 3 near the tip to form an injection port.

The jet tube 3 may have a multi-layered structure, and a plurality of fluid paths may be provided. For example, when the jet tube is a double tube (see FIG. 6), there is a path through which the two fluids of the inner tube 33a and the outer tube 33b pass. Then, water is jetted from the jet port 33c at the tip through water through the inner pipe 33a, and water is jetted between the inner pipe 33a and the outer pipe 33b.
Water can be injected from the side injection port 33d provided in 3b. When the jet tube has a triple structure (see FIG. 7), the water passed through the inner tube 34a is supplied to the jet port 34 at the tip.
d, the water passing between the inner pipe 34a and the middle pipe 34b is jetted from the side jet port 34e, and the air passing between the middle pipe 34b and the outer pipe 34c is jetted from the side jet port 34f. Can be done. Here, it is preferable to provide an injection port on the side surface of the jet pipe 3 so that a plurality of side injection ports 34e from which water is injected and a plurality of side injection ports 34f from which air is injected are alternately arranged. As described above, by changing the position and number of the injection ports or simultaneously using different fluids such as water and air, it is possible to adjust the ejection amount of the earth and sand.

<C> Guide Tube The guide tube 2 is a hollow tube having a length at least equal to the thickness of the bottom mud 6. Here, the bottom mud 6 refers to sludge deposited on the surface layer of the water bottom. The length of the guide tube 2 is a length that penetrates at least the bottom mud 6 when the guide tube 2 is installed on the water bottom, and is a length that the upper portion of the guide tube 2 protrudes from the water bottom in that state. When there is a silt layer 7 between the bottom mud 6 and the sand layer 5, it is preferable that the silt layer 7 has a length that penetrates the silt layer 7 (see FIG. 1). The diameter and length of the guide tube 2 are set so that sand or the like rises between the outer peripheral surface of the jet tube 3 and the inner peripheral surface of the guide tube 2. For example, a steel pipe having a diameter of about 20 cm and a length of about 1.5 m is used as the guide pipe 2.

The guide tube 2 may be provided with a stopper 22 so that the jet tube 3 does not escape upward. For example, four sticks or plate-like stoppers 22 are attached to the inner wall of the guide tube 2 so that the center of the guide tube 2 is slightly wider than the shaft portion 32 of the jet tube 3 (see FIG. 3). As a result, the jet pipe 3 can move freely downward, but when moving upward, it is possible to prevent the expansion of the injection port 31 from being caught by the stopper 22 and the jet pipe 3 from coming out upward. In addition, it is preferable that the cross-sectional area of the stopper 22 be as small as possible so as not to hinder the rise of the sand, and that the stopper 22 be disposed in a minimum number.

<4> Guide The guide 4 is formed in the shape of a truncated cone that extends upward. The shape of the cone is preferably a cone, but may be a polygonal pyramid. The guide 4 is arranged with a gap secured between the guide 4 and the upper end 21 of the guide tube 2. For example, a support member 41 is attached to the upper end 21 of the guide tube 2, and the guide member 4 is supported by the support member 41 (see FIG. 3). When the positional relationship between the jet pipe 3 and the guide pipe 2 when the sand or the like is being raised is constant, the guide 4 may be attached to the jet pipe 3. By arranging the guide 4, sand or the like spouting from the upper end of the guide tube 2 by moving up the gap between the guide tube 2 and the jet tube 3 can be effectively arranged outside the guide tube 2. That is, the sand or the like that has risen along the guide tube 2 collides with the guide 4 and changes its direction, so that the cover sand 51 accumulates outside the guide tube 2 (see FIG. 1).

Hereinafter, the method of sand covering a water bottom according to the present invention will be described with reference to the drawings.

<A> Machine used and application method For example, a sand covering machine 1 provided with a plurality of the above-mentioned earth and sand sampling devices 1
Use 0. FIG. 2 shows a perspective view of an embodiment of the sand covering machine 10. The sand covering machine 10 is attached to the gantry 11 as necessary,
The gantry 11 is hung by a crane or the like. The arrangement interval of the earth and sand sampling device 1 is, for example, a lattice having predetermined intervals in the vertical and horizontal directions.
The grid spacing is, for example, about 1 to 1.2 m.

<B> Installation of Guide Tube The guide tube 2 is inserted into the bottom mud 6 by its own weight or the like. Thereafter, the guide pipe 2 and the jet pipe 3 penetrate into the underwater ground while jet water or the like is jetted from the jet port 31 of the jet pipe 3. The guide tube 2 is inserted at least until it penetrates the bottom mud 6. If possible, the silt layer 7 below the bottom mud 6 is also penetrated. When the installation of the guide tube 2 is completed, the upper portion of the guide tube 2 projects, for example, by about 30 cm from the upper surface of the bottom mud 6.

<C> Insertion of Jet Tube With the guide tube 2 left at the position where it was set, the jet tube 3 is inserted into the sand layer 5 while jetting high-pressure water. Here, the sand layer 5 refers to a layer formed of sand or sandy soil deposited below the bottom mud 6 in the underwater ground. For example, alluvial sediment in the middle and shallow areas corresponds to this. The jet pipe 3 is inserted into the sand layer 5 while being rotated as necessary while jetting high-pressure water or air. When the jet tube 3 is inserted into the sand layer 5 while spraying high-pressure water or air, the sand layer 5 is fluidized,
The water passes through the gap between the jet pipe 3 and the guide pipe 2 and blows up to the bottom of the water to form sand 51 to cover the upper portion of the bottom mud 6. The injection of the high-pressure water or the air is performed until the predetermined sand cover 51 is formed. Here, by moving the jet tube 3 up and down while spraying high-pressure water or the like, or by rotating the jet tube around the axis of the jet tube, it is possible to promote the blowing of sand or the like. It should be noted that the application of the present invention is not limited to the sand layer, but is also applicable to a stratum made of earth and sand. Here, the earth and sand means sand, earth or a mixture of sand and earth.

<D> Pulling out the earth and sand sampling device After the sand cover 51 having a predetermined thickness is formed, the jet pipe 3
And the guide tube 2 is gradually pulled out. The bottom mud 6 is sucked into the holes remaining in the silt layer 7 after the guide tube 2 is pulled out (FIG. 3).
reference). Since a part of the bottom mud 6 is sucked into the underwater ground in this way, the layer thickness of the bottom mud 6 is smaller than before the construction. The extracted sediment collection device 1 is moved to the next place, for example, so that the installation position of the sediment collection device 1 is in a grid pattern, and the above procedure is repeated to complete the entire sand covering ( (See FIG. 4). In addition, it is also possible to cover the sand in various shapes in a plane while considering the ecosystem. For example, there is no need to cover sand in places where underwater organisms have been inhabited before construction, or to cover sand in places like dotted islands. According to the present invention, the replaced sand cover 51 acts as a load to promote the consolidation of the bottom mud 6 and the silt layer 7, so that the water bottom surface starts to sink. Thereby, the covering sand can be completed without greatly changing the height (water depth) of the water bottom before construction.

<E> Other Embodiments Without using the above-mentioned earth and sand collecting apparatus 1, the method of covering the bottom of the water with the following configuration can be implemented. For example, a water jet 92 is attached to the outer periphery of a casing 93 made of a steel pipe or the like and inserted into the underwater ground. Even after the casing 93 is inserted to a predetermined position on the underwater ground, the water jet 92 continues to jet water. Then, sand or sandy soil fluidized by the water jetted from the water jet 92 is sucked up by a sand pump 91 installed inside the casing 93 and discharged above the bottom mud 6. By doing so, the surface of the bottom mud 6 on the water bottom can be covered with the cover sand 51. FIG. 5 shows a conceptual diagram of another embodiment described above. In the configuration of the other embodiments described above, an ejector may be used instead of the sand pump 91. Here, the ejector refers to an upward water jet, and has a function of ejecting sand or the like sucked in the sand layer 5 above the bottom mud 6.

[0025]

The principle of blowing up the earth and sand used in the present invention will be described below.

When the force acting on the sand due to the upward flow of the fluid ejected from the jet pipe 3 is larger than the weight of the sand, the sand floats. Here, the force acting on the sand can be calculated by Expression 1.

[0027]

(Equation 1)

If the force acting on the sand is greater than the weight of the sand, the sand will float. Therefore, the condition under which the sand floats is as shown in Expression 2.

[0029]

(Equation 2)

When P = W−U, if v ₂ > 0, the sand floats.

[0031] Here, the rising speed _{v 1} of the water Equation 1 is calculated by Equation 3.

[0032]

(Equation 3)

Since the drag coefficient Cd in the equation (1) changes according to the Reynolds number, the equation (4) gives the Reynolds number Re.
Is calculated.

[0034]

(Equation 4)

The particle size of the sand is generally from 74 μm to 2.0 mm.
It is. Difference between the rising speed of water and the rising speed of sand v ₃ = 0.1
Assuming m / s, the Reynolds number is about 50-200. Since the relationship between the drag coefficient and the Reynolds number in the case of a sphere is described in the hydraulic formula collection, etc., the drag coefficient Cd is set to 1.0 from the above results and the figure.

Using the values calculated above, a particle size of 0.5
The floating speed of the sand for mm sand is calculated below.

[0037]

(Equation 5)

Since the floating speed of the sand becomes a positive value by the above calculation, the sand floats. Even when the ratio α of the return flow rate to the ejection flow rate is set to 0.5 or 0.7, the floating speed of the sand is v ₂ = 0.01, 0.07 m / s, and the sand floats.

[0039]

According to the present invention, the following method can be obtained because the method of covering sand on the water bottom and the apparatus for collecting earth and sand according to the present invention are as described above. <B> There is no need to remove sludge from the water bottom. For this reason, no treated soil such as dredged soil is generated, and it is possible to solve disposal sites, dumping sites, and economic problems. <B> Since the sediment deposited on the underwater ground can be effectively used, there is no need to separately prepare sand for covering sand. Therefore, the material cost can be reduced, and the environment of the sand pit is not destroyed. <C> The sandy soil layer is formed on the sludge by the sand covering. For this reason, the dissolved oxygen consumption of sludge and the elution of nutrients such as nitrogen and phosphorus are suppressed, and eutrophication of lake water is reduced. <D> The surface layer at the bottom of the water is a layer of sand covering made of sand or sandy soil. For this reason, since the environment of the water bottom is in a favorable condition of the sandy soil system, it is improved as a habitat for freshwater plants and bottom organisms. <E> Only the order of the sedimentary layers on the underwater ground before construction is changed. Therefore, there is little change in the height of the water bottom.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an embodiment of a soil and sand sampling apparatus and a sand covering method according to the present invention.

FIG. 2 is a perspective view of an embodiment of a sand covering machine provided with a plurality of earth and sand sampling devices.

FIG. 3 is an explanatory view when the earth and sand sampling device is pulled out.

FIG. 4 is a cross-sectional view at the time of completion of sand covering method for a water bottom

FIG. 5 is a conceptual diagram of another embodiment of the method of sand covering a water bottom.

FIG. 6 is an explanatory view of an embodiment in a case where the jet tube is a double tube.

FIG. 7 is an enlarged perspective view of the embodiment when the jet tube is a triple tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Soil collection apparatus 2 ... Guide pipe 3 ... Jet pipe 4 ... Guide tool

Continuing from the front page Applicable to Article 30, Paragraph 1 of the Patent Law. Shinken Shimbun, Japan, Shinken Shimbun, November 10, 2000, page 4 (72) Inventor Kazuo Okada Nishi, Shinjuku-ku, Tokyo 1-25-1, Shinjuku, Taisei Construction Co., Ltd. (72) Inventor: Seizou Ueno 1-25-1, Nishi-Shinjuku, Shinjuku, Shinjuku-ku, Tokyo Inside (56) References JP-A-1-94113 (JP, A) JP 5-5010 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) E02B 3/18 E02D 15/10 E02B 3/00 E02F 3/92

Claims (7)

(57) [Claims] 1. A method of sand covering a water bottom, comprising: fluidizing sediment deposited inside a water bottom ground , and covering a surface layer of the water bottom with sand squirted from the inside of the water bottom ground to the water bottom . 2. A sediment collecting apparatus for collecting sediment deposited on a submarine ground, comprising: a hollow guide pipe; and a jet pipe loaded inside the guide pipe. An earth and sand sampling device, characterized in that by injecting a fluid from at least one of the surfaces, earth and sand in the underwater ground rises in a gap between the guide tube and the jet tube and blows up from an upper end of the guide tube. 3. The earth and sand sampling device according to claim 2, wherein the jet pipe has a multiplex structure and a plurality of fluid paths are provided. 4. The earth and sand sampling device according to claim 2, wherein the guiding tool is a truncated pyramid having a shape extending upward and having a gap secured with an upper end of the guide tube. An earth and sand sampling device, comprising: 5. The earth and sand sampling device according to claim 2, wherein the guide pipe is inserted to a predetermined position on a submarine ground so that an upper part of the guide pipe protrudes from a water bottom. The sediment in the underwater ground fluidized by the injected fluid is inserted deeper into the ground while spraying,
A method of covering the bottom of the water, wherein the bottom of the water is covered with earth and sand that has been deposited inside the bottom of the water by ascending the gap between the guide pipe and the jet pipe and blowing up from the upper end of the guide pipe. 6. A method according to claim 5, wherein said jet pipe rotates to eject fluid while rotating, thereby fluidizing earth and sand on the underwater ground. 7. The method according to claim 5, wherein the sand is covered over a wide range of the water bottom by repeating at predetermined intervals in a grid pattern.