JP6315661B2 - Sand-capping method - Google Patents

Description

  The present invention relates to a sandy bottom covering method that can obtain the same effect as the dredging method by covering sludge deposited on the bottom of a lake or the sea with sand or the like.

  Conventionally, dredging methods and sand-capping methods are known as methods for maintaining good water quality and aquatic ecosystems such as lakes and seas.

  The dredging method is a method that exposes the high-quality soil in the lower layer by removing the surface sludge (bottom mud) accumulated on the bottom of the water. Surface sludge has high elution amount, especially nutrient salt elution amount, and high consumption of DO (dissolved oxygen), so leaving the sludge deposited on the bottom of the lake or the sea causes deterioration of water quality. At the same time, it is not preferred for living environments. For this reason, the dredging method is a method of maintaining good water quality and aquatic ecosystem by removing sludge that causes the dredging.

  On the other hand, the sand-capping method is intended to obtain the same effect as the dredging method by using the bottom mud layer of sludge accumulated on the bottom of the water.

  FIG. 1 is a schematic side view conceptually showing a conventional sand-capping method.

  As shown in FIG. 1, the conventional sand-capping method uses a sand-capping material charging machine 3 such as a clamshell bucket on the surface of a bottom mud layer 2 formed by depositing sludge on the bottom 1 of a sea or lake. It is configured such that the sand particles 5 are sprayed directly from the surface of the water or near the water surface 4.

  However, in this method, the fine particles 6 contained in the sandy soil (sand cover material) are diffused into the water during the construction of the sand cover, and it tends to become cloudy, and the sand cover material is deposited on the existing bottom mud. There is a problem that the bottom mud soars and turbidity is likely to occur because the surrounding water is disturbed when the bottom is bottomed. Further, the sand-capping material may sink into the bottom mud layer 2 or on the upper surface of the bottom mud layer 2. There is a risk that turbulent flow will occur, the bottom mud will rise, and the raised bottom mud may settle on the layer of sand-capping material, forming a bottom mud layer on the sand-capping material layer. Assuming that the layer thickness of the material layer is non-uniform, the amount of sand-capping material input is determined, so it is far more than the sand-capping material necessary to form a sand-capping material layer with a predetermined thickness. In addition, there is a problem that a large amount of sand covering material is required.

  Therefore, in order to solve such a conventional problem, Japanese Patent Application Laid-Open No. 2011-163027 (Patent Document 1) uses a slurry obtained by mixing sand-covering material and water from a discharge port disposed so as to face the water bottom. It is proposed to discharge towards the bottom of the water.

  Japanese Patent Laid-Open No. 2003-253672 (Patent Document 2) discloses a guide pipe having a bottom cover on one end face and an opening on the other end face, and a sediment supply pipe for supplying earth and sand to the inside of the guide pipe. With the guide pipe positioned in the vicinity of the bottom mud layer so that the bottom lid is downward, the earth and sand are directed to the bottom lid from the tip of the earth and sand supply pipe through the opening of the guide pipe. Soil-covering sand configured to supply soil and sand, lower the supplied soil and sand along the guide pipe, discharge it from the opening of the guide pipe onto the bottom mud layer, and form a sand-covering layer on the bottom mud The construction method is disclosed.

JP 2011-163027 A JP 2003-253672 A

  Since the slurry of the method disclosed in Japanese Patent Application Laid-Open No. 2011-163027 (Patent Document 1) is merely mixing the sand covering material with water, the sand covering material is still separated from the slurry. There is a problem that it is difficult to completely eliminate the possibility of turbidity due to diffusion.

  On the other hand, the sand-capping method described in Japanese Patent Application Laid-Open No. 2003-253672 supplies earth and sand from the earth and sand supply pipe toward the bottom cover of the guide member, overflows from the opening of the guide member, and then on the bottom mud layer. It forms a sand-covering layer and can form a sand-covering layer without disturbing the bottom mud, but it supplies soil into the water, so it is included in the sand that overflows from the opening of the guide member There is a problem that it is difficult to completely prevent fine particles from diffusing into water and causing turbidity.

  Therefore, the present invention prevents the fine particles contained in the sand-covering material from diffusing into the water and causing turbidity during construction of the sand-covering sand, and also when the sand-covering material settles on the existing bottom mud. In addition, the sand cover material disturbs the surrounding water, the bottom mud rises, and the raised bottom mud settles on the sand cover material layer to prevent the bottom mud layer from forming on the sand cover material layer. However, it is an object of the present invention to provide a sand covering method capable of forming a sand covering layer on the upper surface of the bottom mud layer without using a much larger amount of sand covering material than a necessary sand covering material.

In a preferred embodiment of the present invention, a sand-covering material plate formed by sand particles being hardened in a plate shape with a biodegradable binder consisting of eggs is suspended by a crane to the upper surface of the bottom mud layer to be sand-covered. The bottom mud layer is grounded to cover the upper surface of the bottom mud layer, and with the passage of time, the sand covering material plate is unsolidified and a sand covering layer of sand particles is formed.

In another preferred embodiment of the present invention, the sand particles are hardened in a spherical shape with a biodegradable binder composed of eggs , and the resulting spherical sand covering material is inserted into the upper surface of the bottom mud layer to be sand covered. Dropped by a close sand covering material throwing machine to cover the upper surface of the bottom mud layer, and over time, the spherical sand covering material is solidified and a sand covering layer of sand particles is formed. Yes.

  In the present invention, zeolite particles are preferably used as sand particles. Zeolite can adsorb cesium, which is a radioactive substance, and zeolite is particularly suitable as a sand covering material for covering a bottom mud layer contaminated by cesium.

  According to the present invention, at the time of sand-covering construction, fine particles contained in the sand-covering material are diffused into the water to prevent turbidity, and the sand-covering material settles on the existing bottom mud. In addition, the sand cover material disturbs the surrounding water, the bottom mud rises, and the raised bottom mud settles on the sand cover material layer to prevent the bottom mud layer from forming on the sand cover material layer. And it becomes possible to provide the sand-covering method which can form a sand-covering layer on the upper surface of a bottom mud layer, without using much sand-covering material much more than required sand-covering material.

FIG. 1 is a schematic side view conceptually showing a conventional sand-capping method. FIG. 2 is a schematic side view conceptually showing a preferred embodiment of the sand-capping method according to the present invention. FIG. 3 is a schematic side view conceptually showing a state in which the binding material of the sand covering plate placed on the upper surface of the bottom mud layer is biodegraded. FIG. 4 is a schematic side view conceptually showing another preferred embodiment of the sand-capping method according to the present invention. FIG. 5 is a schematic side view conceptually showing a state in which the binder of the spherical sand covering material dropped on the upper surface of the bottom mud layer is biodegraded.

  FIG. 2 is a schematic side view conceptually showing a preferred embodiment of the sand-capping method according to the present invention. In FIG. 2, the same reference numerals are given to the parts common to FIG.

  As shown in FIG. 2, in this embodiment, the zeolite particles are combined in a plate shape with a biodegradable binding material such as egg, agar, gelatin, etc., and the sand covering material plate 8 is generated and generated. The sand-clad material plate 8 is placed on the upper surface of the bottom mud layer 2 formed by depositing sludge on the bottom 1 of the sea or lake using a crane 10 fixed to a work boat (not shown). The

  Zeolite can adsorb cesium, which is a radioactive substance, and zeolite is particularly suitable as a sand covering material for covering a bottom mud layer contaminated by cesium.

  Here, since the zeolite particles that are sand-capping material are bound by the biodegradable binder, it is ensured that the fine particles contained in the sand-capping material diffuse into the water and cause turbidity as in the past. Can be prevented.

  Moreover, in this embodiment, since it is comprised so that the sand-covering material plate 8 may be mounted in the upper surface of the bottom mud layer 2, the sand-covering material plate 8 suppresses the rise of bottom mud, Therefore It is possible to effectively prevent mud from rising and causing turbidity, or rising bottom mud to settle on the sand covering material layer and forming the bottom mud layer 2 on the sand covering material layer. become.

  However, when the sand-capping material plate 8 is placed on the upper surface of the bottom mud layer 2, the bottom mud rises and turbidity occurs, or the raised bottom mud settles on the sand-carrying material layer and covers the sand. It is preferable that the sand covering material plate 8 is slowly placed on the bottom mud layer 2 by the crane 10 so that the bottom mud layer 2 is not formed on the material layer.

  Thus, the sand-capping material plate 8 placed on the upper surface of the bottom mud layer 2 is one in which zeolite particles are bound in a plate shape by a biodegradable binding material such as egg, agar, gelatin, As shown in FIG. 3, the binder gradually decomposes with time, and the bottom mud layer 2 is covered with the zeolite particles to form the sand covering material layer 11.

  According to this embodiment, the zeolite particles, which are sand-covering materials, are bound together by the biodegradable binding material, and the sand-covering material plate 8 is generated and placed on the upper surface of the bottom mud layer 2. In addition, it is possible to reliably prevent the fine particles contained in the sand covering material from diffusing into the water and causing turbidity.

  Furthermore, according to this embodiment, the sand-capping material plate 8 is formed by coating zeolite particles with a biodegradable binding material such as egg, agar, gelatin, etc., and the binding material decomposes over time. Therefore, the upper surface of the bottom mud layer 2 can be uniformly coated with the zeolite particles, and the sand covering material layer 11 can be formed.

  In addition, according to the present embodiment, biodegradable binders such as eggs, agar, and gelatin are used as the binder for binding the zeolite particles to generate the sand-clad material plate 8. It is possible to uniformly coat the upper surface of the bottom mud layer 2 with zeolite particles without adversely affecting the sand-clad material layer 11.

  Furthermore, according to this embodiment, since the sand-clad material plate 8 is placed on the upper surface of the bottom mud layer 2 so as to cover the upper surface of the bottom mud layer 2, the bottom mud soars and turbidity occurs, It can prevent effectively that the bottom mud which soared settles on the sand-covering material layer 11, and the bottom mud layer 2 is formed on the sand-covering material layer 11. FIG.

  FIG. 4 is a schematic side view conceptually showing another preferred embodiment of the sand-capping method according to the present invention. In FIG. 4, the same reference numerals are given to portions common to FIG. 1.

  As shown in FIG. 4, in this embodiment, the zeolite particles are bonded in a spherical shape by a biodegradable binding material such as egg, agar, or gelatin to produce a spherical sand-clad material 9. Using a sand-capping material charging machine 3 such as a clam shell bucket fixed to the bottom mud layer 2 formed by depositing sludge on the bottom 1 of the sea or lake. Dropped.

  At this time, as much as possible, place the sand-covering material charging machine 3 such as a clamshell bucket so that the spherical sand-covering material 9 does not disturb the surrounding water and the bottom mud soars, It is preferable to drop the spherical sand covering material 9 on the upper surface of the bottom mud layer 2.

  In addition, since the zeolite particles, which are sand-capping materials, are bound by a biodegradable binder, it is ensured that the fine particles contained in the sand-covering materials diffuse into the water and cause turbidity as in the past. Can be prevented.

  As shown in FIG. 4, the spherical sand covering material 9 is uniformly distributed on the surface of the bottom mud layer 2 formed by depositing sludge on the bottom 1 of the sea or lake.

  As described above, the uniformly distributed spherical sand-clad material 9 formed on the upper surface of the bottom mud layer 2 is a material in which zeolite particles are spherically bound by a biodegradable binding material such as egg, agar, or gelatin. Therefore, as shown in FIG. 5, the binding material gradually decomposes with time, and the bottom mud layer 2 is covered with the zeolite particles to form the sand covering material layer 11.

  According to this embodiment, the zeolite particles that are sand-covering materials are bound by the biodegradable binding material, and the spherical sand-covering material 9 is generated and dropped on the upper surface of the bottom mud layer 2. The fine particles contained in the sand-capping material can be reliably prevented from diffusing into water and causing turbidity.

  Further, according to the present embodiment, the spherical sand-clad material 9 is formed by coating zeolite particles with a biodegradable binder such as egg, agar, gelatin, etc., and the biodegradable binder with time. Therefore, the upper surface of the bottom mud layer 2 can be uniformly covered with the zeolite particles to form the sand covering material layer 11.

  In addition, according to the present embodiment, biodegradable binders such as eggs, agar, and gelatin are used as binders that bind the zeolite particles to produce the spherical sand-clad material 9, so that the surrounding environment is used. It is possible to uniformly coat the upper surface of the bottom mud layer 2 with zeolite particles without adversely affecting the sand-clad material layer 11.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say.

  For example, in the above embodiment, zeolite particles are used as the sand covering material. However, in the present invention, since the sand covering material is bound by a biodegradable binder, the sand covering material is limited to the zeolite particles. However, other sand-capping materials such as clinker porous particles can also be used.

DESCRIPTION OF SYMBOLS 1 Water bottom 2 Bottom mud layer 3 Sand covering material injection machine 4 Water surface 5 Sand grain 6 Fine particle 8 Sand covering material plate 9 Spherical sand covering material 10 Crane 11 Sand covering material layer

Claims (3)

A sand-clad material plate, which is formed by solidifying sand grains into a plate shape with a biodegradable binder consisting of eggs , is suspended by a crane to the upper surface of the bottom mud layer to be sanded, and then settled down. Covering the top surface,
With the passage of time, the solidification of the sand-covering material plate of the binding material is released, and a sand-covering layer of sand particles is formed,
Sand-capping method. Sand particles are hardened in a spherical shape with a biodegradable binder consisting of eggs , and the resulting spherical sand-clad material is dropped by a sand-carrying material feeder that closes the inlet to the upper surface of the bottom mud layer to be sanded. Covering the upper surface of the bottom mud layer,
Over time, the solidification of the spherical sand-clad material is released, and a sand-clad layer is formed by sand particles,
Sand-capping method.   The sand-capping method according to claim 1 or 2, wherein the sand particles are zeolite particles.

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