JP4067100B2 - Sediment flow method - Google Patents

Description

  The present invention relates to a method for conveying earth and sand, and more particularly, to a method for conveying earth and sand floating in a water stream.

  In reservoirs such as dams, the accumulation of sediment flowing in from the upstream will reduce the effective water storage capacity and cause erosion of downstream rivers and coasts, etc., so the permanent use of reservoirs and improvement of sediment environment in rivers and coasts, etc. For this purpose, it is required to discharge and supply the sediment accumulated in the reservoir (hereinafter sometimes referred to as sediment) to the downstream as appropriate. For example, a method has been developed in which sediment is allowed to flow downstream along with running water during floods such as heavy rain. However, if a large amount of sediment is discharged to the downstream at once, there is a possibility that it will greatly affect the biological habitat environment downstream. Therefore, conventionally, sediment is carried out from the reservoir by dredgers, pipe suction, conveyors, etc., and the carried sediment is transported to an appropriate downstream position by a dump truck, etc., so that it does not affect the biological habitat environment. The method has been implemented.

  Patent Document 1 manufactures a collapsible block by mixing sediment collected from a dam reservoir with a solidifying agent having a low bond strength, and arranges the collapsible block as a structure such as a water control system in the basin downstream of the dam. Disclosed is a method for treating dam deposits. Patent Document 2 discloses a method for treating dam sediment, in which a collapsible concrete block prepared by combining dam sediment with aggregate, cement, admixture, or cement and crushed material is disposed on the downstream side of the dam. Has proposed. These collapsible blocks (concrete blocks) disintegrate in a short period of time due to water penetration, impact force, and repeated freezing and thawing, and gradually release the sediment as disintegrated sand. It can be supplied downstream.

Japanese Patent Laid-Open No. 6-073717 JP-A-6-157107

  However, the methods of Patent Documents 1 and 2 are effective for supplying sand and stones having a relatively large particle size among sediments to the downstream, but small mud and silt components (hereinafter referred to as these). ) Is not suitable for supplying the mud downstream. If only sand and stones are supplied downstream, it is difficult to properly improve the downstream sediment environment (for example, the particle size distribution of the sediment). In addition, if mud that is difficult to use as aggregate is discharged downstream, the COD (chemical oxygen consumption) and turbidity of the river will rise, and the algae breeding environment and riverbed that will feed the river fish (such as salmon) May worsen the aquatic insect habitat. It is conceivable that the mud is loaded on a dump truck or the like and transported downstream, but in that case, the dried mud may be scattered during transport, which may cause a new dust problem. Development of technology that can supply mud with sand and stones downstream is desired.

Moreover, the method of patent document 1 and 2 requires the transportation energy for conveying the manufactured collapsible block downstream, and requires enormous transportation energy in order to convey a large amount of sediment. For example, when transporting large amounts of disintegrating blocks dump truck or the like, not only requires transportation energy also results in environmental problems such as noise and C0 ₂ emissions. Economic transportation of a large amount of earth and sand in this way is an important issue not only for countermeasures against sedimentation in reservoirs but also for countermeasures against earth and sand generated by earth work.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a water flow floating transport method that economically transports earth and sand containing mud.

Referring to the embodiment of FIG . 1 and FIG. 4, in the method of conveying the earth and sand according to the present invention, the earth and sand 2 is enclosed in the film 11 together with the foaming agent 12 , and the earth and sand 2 is formed by the bubbles 13 generated from the foaming agent 12. It floats on the water stream 7 and is conveyed.

  More preferably, the amount of the foaming agent 12 is adjusted according to the planned transport distance of the earth and sand 2, the flow velocity of the water flow 7, and the airtightness of the membrane 11. For example, the amount of the foaming agent 12 can be adjusted so that the earth and sand 2 are transported a predetermined distance and then sink to the bottom of the water together with the film 11. It is also possible to collect the earth and sand 2 transported for a predetermined distance from the water flow 7 together with the film 11, dissolve the film 11 with the film dissolving agent 21, and take out the earth and sand 2.

According to the present invention, the method of conveying the earth and sand by floating it encloses the earth and sand together with a foaming agent in a film (hereinafter sometimes referred to as a coating film), and floats the earth and sand on the water stream by bubbles generated from the foaming agent and conveys it to a required position. Therefore, the following remarkable effects are produced.

(B) The earth and sand can be transported to the required position in an energy-saving and economical manner by using natural water currents such as rivers without artificially applying energy.
(B) Since not only sand and stone but also mud can be transported together, it can be effectively used to improve the sediment environment of downstream rivers and coasts.
(C) It can be used effectively not only for sedimentation measures in dam reservoirs but also for transporting earth and sand at ground construction sites such as ground drilling and tunnel construction sites where a large amount of mud is generated.
(D) Since soil and sand are enclosed in a film and transported, the risk of environmental problems such as increased COD and increased turbidity is small even when rivers are used.
(E) In addition, there is no possibility of causing environmental problems in noise and C0 ₂ emissions or the like relative to the transport of sediment by conventional track such, it can be said that an extremely clean transfer method.
(F) Since the earth and sand are floated and conveyed using a foaming agent that generates bubbles, the distance of earth and sand can be adjusted by adjusting the amount of the foaming agent, and the earth and sand can be submerged at a required position downstream.
(G) By using a film made of a material that is easily decomposed in the natural world (sea area, river area, etc.), even when earth and sand settles on the bottom of the water together with the film, the load on the water area can be suppressed sufficiently small.

  FIG. 1 shows an embodiment of the present invention applied to the case where sedimentation in the dam reservoir 1 is supplied to a downstream river area / sea area. In the illustrated example, the earth and sand 2 which is sediment in this case is collected from the reservoir 1 by a collecting device 4 such as a dredger, a suction pipe and a conveyor, and a low specific gravity substance 16 is added by an adding device 5 and then a coating film is formed by a coating device 6. Wrap with 11. The sediment 2 wrapped in the membrane 11 together with the low specific gravity material 16 is discharged into a natural water stream 7 which is a river in this case, suspended and transported to the estuary and other required positions, and the sediment 2 is transported together with the membrane 11 at the downstream required location. Collect or settle to bottom with membrane 11. In the present invention, mud can be enclosed in the membrane 11 together with sand and stones and supplied downstream, which is effective for measures against sedimentation for the purpose of improving the sediment environment of rivers and coasts. However, the present invention is not limited to the conveyance of the sediment 2 but can also be applied to the conveyance of the earth and sand 2 generated at, for example, an earthwork site or a tunnel construction site. The water flow 7 is not limited to a natural flow such as a river, and an appropriate artificial water flow 7 can be used.

  FIG. 2 shows an example of a flow chart until the earth and sand 2 collected from the reservoir 1 is enclosed in the coating film 11 and discharged into the water stream 7. In this example, the coating apparatus 6 includes a film forming agent 15 and a film forming agent 14 that forms the film 11 by a reaction with the film forming agent 15. The earth and sand 2 are mixed with the film forming agent 14 and immersed in the film forming agent 15 to be enclosed with the film 11. An example of the film forming agent 14 is a polysaccharide having a carboxyl group such as alginic acid, carboxymethyl cellulose (CMC), or a pectin solution, and an example of the film forming agent 15 is a calcium ion solution (for example, an aqueous calcium hydroxide solution). Alginic acid is a material extracted from seaweed, and other polysaccharides are used as food additives and the like, and all are biodegradable materials.

  In the method of forming the coating film 11 by the reaction of the film forming agent 14 and the film forming agent 15 shown in FIG. 2, the earth and sand 2 can be enclosed in the film 11 in a water-containing state, so that the mud-containing earth and sand 2 is semi-dried. There is an advantage that it can be easily sealed in the film 11 in the state. As will be described later, the thickness and strength of the coating film 11 can be adjusted to such an extent that the film forming agent 14 can withstand a collision with a rock or the like during conveyance by adjusting the concentration and the mixing amount of the film forming agent 14. Furthermore, by making the membrane 11 made of a biodegradable material, even when the membrane 11 is dispersed in the water stream 7, it can be expected to decompose in nature, and the membrane-enclosed earth and sand 10 is secured while ensuring environmental safety. The earth and sand 2 can be supplied to the downstream area by being naturally collapsed. However, instead of the coating film 11 shown in the figure, for example, a capsule made of a reinforced rubber resin, a water-soluble vinylon film, or the like may be used.

In the example of FIG. 2, bubbles 13 in which a foaming agent 12 is generated are used as the low specific gravity material 16 for floating the earth and sand 2 on the water surface (see also FIG. 4). Various blowing agents 12 belonging to the prior art can be used. For example, tartaric acid (C ₄ H ₆ O ₆ ) and sodium bicarbonate (NaHCO ₃ ) can be used to generate carbon dioxide (CO ₂ ). The foaming agent 12 containing tartaric acid and baking soda is used as a contrast agent for human stomach X-ray examination and the like, and even if dispersed in the water stream 7, it is unlikely to become a source of contamination. However, instead of the foaming agent 12, the gas may be enclosed in the coating film 11 as it is, and the earth and sand 2 can be floated on the water surface by using other appropriate low specific gravity substances 16.

  In step 201 in FIG. 2, the earth and sand 2 are scooped up from the reservoir 1, and moisture is dried to some extent as necessary. In step 202, for example, a film forming agent 14 such as a sodium alginate aqueous solution or a CMC sodium aqueous solution is dissolved in water to prepare an aqueous solution having a required concentration. In step 203, the foaming agent 12 is added to the earth and sand 2, and in step 205, the earth and sand 2 and the aqueous solution of the film forming agent 14 are mixed. In the figure, in order to delay the start of foaming, for example, only tartaric acid is added to the earth and sand 2 in step 202, sodium bicarbonate is added to the film forming agent 14 in step 204, and tartaric acid and sodium bicarbonate are mixed in step 205. Further, in Step 206, the mixture of the earth and sand 2, the foaming agent 12 and the film forming agent 14 is formed into an appropriate shape and size (size), and is put into the film forming agent 15 such as an aqueous calcium hydroxide solution for an appropriate time (for example, (Several minutes to several hundred minutes) Immersion is performed to form a film-containing earth and sand 10 in which the earth and sand 2 and the foaming agent 12 are wrapped with the coating film 11 as shown in FIG. The shape and size of the membrane-enclosed earth and sand 10 can be appropriately selected according to the condition of the water stream 7 to be discharged (for example, presence or absence of rocks), depth, flow velocity, flow rate, etc. For example, the size is several cm to several tens of cm And the shape can be spherical, cylindrical, trigonal, elliptical, or the like.

[Experimental example]
In order to confirm whether or not the membrane-enclosed earth and sand 10 wrapped in the coating film 11 by the method of FIG. 2 can float on the water stream 7, the concentration of the film-forming agent 14 (see step 202), the foaming agent 12 relative to the earth and sand 2 Experiments were conducted to confirm the possibility of floating of the membrane-enclosed earth and sand 10 on the water while changing the amount added (see steps 203 and 204) and the amount of the film-forming agent 14 mixed with the earth and sand 2 (see step 205). In this experiment, three types of aqueous solutions of alginic acid having a concentration of 4%, 2%, and 1% were used as the film forming agent 14, and tartaric acid and sodium bicarbonate were used as the foaming agent 12. Add 10g of tartaric acid and sodium bicarbonate 0.1g, 0.2g, or 0.3g to 10g of earth and sand 2 and mix 5g, 10g, or 20g of any one of the three types of film formers, and add tartaric acid and sodium bicarbonate. Whether or not the membrane-enclosed earth and sand 10 in which the coding film 11 is formed by immersing each of the earth and sand samples having different mixing amounts of the aqueous solution and the alginic acid aqueous solution in a calcium chloride aqueous solution (for example, concentration 0.2M to 0.4M) for 2 minutes. confirmed. Moreover, when it floated, the floating time until it sinks in water was measured. Table 1 shows the experimental results according to the concentration of the alginate aqueous solution, where the case where the membrane-enclosed earth and sand 10 floats on the water is indicated as ◯, and the case where it is not indicated as ×.

  As can be seen from the experimental results of Sample Nos. 21 to 29 in Table 1, in the aqueous solution of alginic acid having a concentration of 1%, the coating film 11 is too thin and is easily broken by bubbles generated from tartaric acid and baking soda, and the earth and sand 2 is flown through the water 7 Could not be suspended. Further, as can be seen from the experimental results of Sample Nos. 1 to 3 and Samples Nos. 11 to 13, when the amount of the alginate aqueous solution is less than the amount of earth and sand, the film 11 having sufficient strength cannot be formed, 2 could not be suspended in the water stream 7. Furthermore, in samples Nos. 4 to 9 and Nos. 14 to 19 in Table 1, the coding membrane 11 that floats the earth and sand 2 in the water stream 7 could be formed, but when the amount of tartaric acid and sodium bicarbonate added was 0.1 g, the membrane was enclosed. It was confirmed that the water floating time of the membrane-enclosed earth and sand 10 increased as the amount of tartaric acid and sodium bicarbonate added increased to 0.2 g and 0.3 g. The reason why the floating time on the water becomes longer depending on the amount of tartaric acid and sodium bicarbonate added is that the calcium alginate gel film formed by the reaction of alginic acid and calcium ions has some air permeability, so that the dioxide produced by the reaction of tartaric acid and sodium bicarbonate. This is thought to be due to the longer time for carbon to dissipate.

  From the experimental results in Table 1, it can be seen that the film 11 floating in the water stream 7 can be formed by mixing the film forming agent 14 having a concentration of 2% or more with the earth and sand 2 in the same amount or more. In order to economically form the coding film 11 floating in the water stream 7, it is appropriate that the concentration of the film forming agent 14 is 2 to 4% and the mixing amount with respect to the earth and sand 2 is about 1: 1 to 2. . It can also be seen that the floating time of the membrane-enclosed earth and sand 10 on the water can be adjusted by adjusting the amount of the foaming agent 12 added according to the airtightness of the membrane 11. If the floating time of the membrane-enclosed earth and sand 10 is adjusted according to the flow velocity of the water stream 7, the transport distance of the membrane-enclosed earth and sand 10 by the water stream 7 can be predicted. When using a film-forming agent 14 and foaming agent 12 other than alginic acid aqueous solution, tartaric acid and baking soda, as in the experiment of Table 1, the appropriate mixing amount and addition amount are experimentally determined according to the floating time of earth and sand 2. be able to.

  For example, in the embodiment of FIG. 1, the earth and sand 2 is wrapped with a film 11 having sufficient strength to float in the water stream 7, and the airtightness of the film 11, the planned transport distance from the discharge position to the estuary 9, and the flow velocity of the water stream 7 Accordingly, by adjusting the amount of the foaming agent 12 added, the membrane-filled earth and sand 10 can be floated and conveyed in the water stream 7 to the estuary 9 and submerged in the bottom of the estuary 9. The membrane-enclosed earth and sand 10 sinking to the bottom of the estuary 9 gradually collapses the membrane 11 made of a biodegradable material and flows out of the earth and sand 2 and supplies the earth and sand 2 to the beach and tidal flat 8 adjacent to the estuary 9. That is, the present invention can be effectively used for recovery and regeneration of the tidal flat 8. Similarly, it is also possible to supply the earth and sand 2 to the downstream position by adding the foaming agent 12 so as to sink at the required downstream position of the water stream 7.

  In addition, as shown in FIG. 1, the membrane-enclosed earth and sand 10 is floated and transported to the river mouth 9 in the water stream 7 and collected, and the collected membrane-enclosed earth and sand 10 is introduced into the membrane dissolving apparatus 20 to melt the membrane 11 and the earth and sand. It is also possible to take out 2 and supply the taken out earth and sand 2 to the creation of a beach or a tidal flat 8. For example, the film 11 formed by the reaction between alginic acid and a calcium ion solution is dissolved in an alkaline solution (such as an aqueous sodium hydroxide solution). The film 11 made of a water-soluble vinylon film dissolves when immersed in high-temperature water (for example, 30 ° C. or more) for a required time (for example, 90 minutes or more). An example of the membrane dissolving apparatus 20 in the illustrated example includes a membrane dissolving agent 21 (membrane dissolving solution) such as an alkaline solution or high-temperature water.

  According to the present invention, mud contained in the earth and sand 2 can be enclosed in the membrane 11 together with sand and stones, and can be transported economically using natural flows such as rivers, and energy-saving earth and sand transport is possible. It becomes. Further, by adjusting the mixing amount of the film forming agent 14 with respect to the earth and sand 2 and the addition amount of the foaming agent 12, the earth and sand 2 is conveyed while being wrapped in the film 11 to the required downstream position of the water stream 7, and the film at the required downstream position. 11 can be naturally collapsed to allow the sediment 2 to flow out, or the sediment 2 can be recovered together with the membrane 11. Furthermore, by discharging a plurality of membrane-enclosed earth and sand 10 having different addition amounts of the foaming agent 12, the membrane-enclosed earth and sand 10 can be naturally collapsed at various positions in the water stream 7 and supplied to the specific position.

  Thus, it is possible to achieve the “water flow floating conveying method for economically conveying mud-containing earth and sand” which is an object of the present invention.

  FIG. 3 shows an embodiment of another method for wrapping earth and sand 2 with a coating film 11. In this embodiment, instead of mixing the earth and sand 2 and the film-forming agent 14 as shown in FIG. 2, the film-forming agent 14 is applied to the surface of the earth and sand 2 so as to be wrapped in clothing, as shown in FIG. 4 (B). The coating film 11 is formed by immersing the earth and sand 2 coated with the film forming agent 14 in the film forming agent 15. Compared to the method of mixing the earth and sand 2 and the film forming agent 14, the method of applying the film forming agent 14 to the surface of the earth and sand 2 saves the amount of the film forming agent 14 necessary for enclosing the earth and sand 2. Can be economical.

  In step 301 of FIG. 3, the earth and sand 2 picked up from the reservoir 1 is formed into an appropriate shape. When the earth and sand 2 are dry, you may shape | mold by adding water suitably as needed. In step 302, the foaming agent 12 is added to the aqueous solution of the film forming agent 14 to prepare an aqueous solution of the film forming agent 14 containing the foaming agent. For example, the aqueous solution of the film forming agent 14 containing the foaming agent is applied to the surface of the molded earth and sand 2 Thus, the earth and sand 2 are wrapped with the film forming agent 14 and the foaming agent 12. In step 304, the earth and sand 2 having the surface coated with the film forming agent 14 and the foaming agent 12 are dipped in the film forming agent 15, so that the earth and sand 2 and the foaming agent 12 are coated as shown in FIG. A film enclosing earth and sand 10 wrapped with 11 is formed. Also in this figure, the appropriate mixing amount of the film forming agent 14 and the appropriate addition amount of the foaming agent 12 can be experimentally adjusted according to the floating time of the earth and sand 2.

  In the flowchart of FIG. 3, after the earth and sand 2 are wrapped in the film forming agent 14 and the foaming agent 12 in step 302, the film forming agent 14 is further applied to the surface and immersed in the film forming agent 15 (step 303). . When the foaming agent 12 is mixed into the coating film 11 that encloses the earth and sand 2, the film 11 is easily broken by foaming of the foaming agent 12. In step 303, the film forming agent 14 is applied to the outside of the foaming agent 12, and then immersed in the filming agent 15. Thus, the foaming agent 12 is prevented from being mixed into the inside of the film 11, and the coating has sufficient strength and is not easily broken. Formation of the film 11 can be expected. However, if the film 11 having sufficient strength can be formed in the state of step 302 in which the film forming agent 14 and the foaming agent 12 are applied to the surface, step 303 can be omitted.

It is explanatory drawing of one Example of this invention. It is explanatory drawing of an example which forms an earth-and-sand enclosure film | membrane using a film forming agent and a film forming agent. It is explanatory drawing of another example which forms an earth-and-sand enclosure film | membrane using a film forming agent and a film forming agent. FIG. 4 is a schematic cross-sectional view of a membrane-sealed earth and sand formed by the method of FIGS. 2 and 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Dam reservoir 2 ... Sediment 4 ... Sediment collection device 5 ... Additive device 6 ... Coating device 7 ... Water flow 8 ... Beach and tidal flat 9 ... Estuary 10 ... Membrane-containing sediment
11 ... Membrane 12 ... Foaming agent
13 ... Bubbles 14 ... Film-forming agent
15 ... Filming agent
20 ... Membrane dissolving device 21 ... Membrane dissolving agent

Claims (7)

A water-floating transport method for earth and sand, wherein earth and sand are enclosed in a film together with a foaming agent , and the earth and sand are floated and transported by air bubbles generated from the foaming agent . 2. The method according to claim 1, wherein the amount of the foaming agent is adjusted in accordance with a planned transport distance of the earth and sand, a flow velocity of the water stream, and an airtightness of the film. The method according to claim 1 or 2 , wherein the amount of the foaming agent is adjusted such that the amount of the foaming agent is adjusted to sink to the bottom of the water together with the membrane after the earth and sand are conveyed by a predetermined distance. The method according to claim 1 or 2 , wherein the earth and sand transported for a predetermined distance are collected from the water flow together with the film, and the film is melted with a film dissolving agent to remove the earth and sand. 5. The method according to claim 1 , wherein the membrane is made of a material capable of biodegradation. 6. The conveying method according to claim 5 , wherein a film forming agent that forms a film by reaction with a film forming agent is mixed or applied to the earth and sand, and the earth or sand to which the film forming agent is mixed or applied is immersed in the film forming agent. A method of conveying the earth and sand entrained by the membrane according to the above method. The method according to claim 6 , wherein the film-forming agent is alginic acid, carboxymethylcellulose, or a pectin solution, and the film-forming agent is a calcium ion solution.

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