Control method

Abstract

To properly control at least one of water in the ground and water on the ground surface.SOLUTION: The control method includes a step of providing an ion supplying material containing at least one of a first compound capable of generating cations constituting a sparingly soluble salt and a second compound capable of generating anions constituting a sparingly soluble salt in a region where water flows in at least one of the ground and the ground surface, and a step of reducing a flow rate of water on a downstream side of the ion supplying material by precipitating the sparingly soluble salt around the ion supplying material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to techniques for controlling underground and surface water. [Background technology]

[0002] Groundwater can cause pollution and disasters. For example, if hazardous substances leaking from industrial waste disposal sites or radioactive waste disposal sites mix with groundwater, the rivers, lakes, oceans, and surrounding soil into which the groundwater flows can be contaminated with the hazardous substances (see, for example, Non-Patent Document 1). In addition, groundwater seepage can loosen the ground, causing landslides and damage to structures such as levees. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] "Development of a method for removing iron and heavy metals from mine wastewater using an iron concretion process," Eiichi Yoshida, Koji Yamamoto, Ippei Maruyama, Nagoya University Museum Report, http: / / www.num.nagoya-u.ac.jp / media / report / docs / 037_04.pdf, August 30, 2021 Summary of the Invention [Problem to be solved by the invention]

[0004] Installing underground impermeable walls to block groundwater requires a significant amount of construction time and cost, so there is a need for technology that can effectively control groundwater using simpler methods.

[0005] The present disclosure has been made in view of such problems, and its purpose is to provide a technology for appropriately controlling water underground and on the surface of the earth. [Means for solving the problem]

[0006] In order to solve the above problems, a control method according to one embodiment of the present disclosure includes the steps of providing an ion supply material containing at least one of a first compound capable of generating cations that constitute poorly soluble salts and a second compound capable of generating anions that constitute poorly soluble salts in an area where water flows underground and / or on the surface of the earth, and reducing the flow rate of water downstream of the ion supply material by precipitating poorly soluble salts around the ion supply material. [Effects of the Invention]

[0007] According to the present disclosure, underground and surface water can be appropriately controlled. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing a schematic configuration of a groundwater control facility according to an embodiment of the structure of the present disclosure; [Figure 2] FIG. 10 is a diagram illustrating a schematic configuration of another example of a groundwater control facility according to an embodiment. [Figure 3] FIG. 10 is a diagram illustrating a schematic configuration of another example of a groundwater control facility according to an embodiment. [Figure 4] FIG. 10 is a diagram illustrating a schematic configuration of another example of a groundwater control facility according to an embodiment. [Figure 5] FIG. 10 is a diagram illustrating a schematic configuration of another example of a groundwater control facility according to an embodiment. [Figure 6] FIG. 10 is a diagram illustrating a schematic configuration of another example of a groundwater control facility according to an embodiment. [Figure 7] FIG. 10 is a diagram illustrating a schematic configuration of another example of a groundwater control facility according to an embodiment. [Figure 8] FIG. 10 is a diagram illustrating a schematic configuration of another example of a groundwater control facility according to an embodiment. [Figure 9] FIG. 10 is a diagram illustrating a schematic configuration of another example of a groundwater control facility according to an embodiment. [Figure 10] FIG. 10 is a diagram illustrating a schematic configuration of another example of a groundwater control facility according to an embodiment. [Figure 11]FIG. 10 is a diagram illustrating a schematic configuration of another example of a groundwater control facility according to an embodiment. [Figure 12] 1 is a flowchart showing the steps of a groundwater control method according to an embodiment. [Figure 13] 1 is a flowchart showing the steps of a method for repairing a groundwater control facility according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] This disclosure describes a technique for controlling the flow rate, flow direction, and retention amount of water present underground or on the earth's surface. In a control method according to an embodiment of the disclosure, an ion supply material containing at least one of a first compound capable of generating cations that constitute poorly soluble salts and a second compound capable of generating anions that constitute poorly soluble salts is provided in an area where water exists underground or on the earth's surface. Precipitation of poorly soluble salts around the ion supply material changes at least one of the flow rate, flow direction, and retention amount of water.

[0010] The water that can be controlled by the control method of the present disclosure is all water that exists underground or on the ground, regardless of whether it is seawater or freshwater. The control method of the present disclosure can control water that has infiltrated into the ground from rivers, ponds, lakes, waterways, seas, canals, etc., water that has formed on the ground in large quantities due to rainfall, typhoons, tornadoes, river flooding, etc., water that exists in rivers, ponds, lakes, waterways, seas, canals, etc., and water that has formed on the ground in large quantities due to rainfall, typhoons, tornadoes, river flooding, etc.

[0011] When controlling groundwater, seepage water, etc. present underground, the ion supplying material may be provided underground, such as in soil, ground, bedrock, or the seabed. When controlling river water, seawater, etc. present on the ground's surface, the ion supplying material may be provided on the ground or underground in contact with the river water, seawater, etc. As will be described later, ions supplied from the ion supplying material diffuse into the surroundings and precipitate sparingly soluble salts, so it is desirable to provide the ion supplying material in a location where the ions supplied from the ion supplying material can diffuse into the surroundings.

[0012] 1 shows a schematic configuration of a groundwater control facility according to an embodiment of the structure of the present disclosure. If hazardous substances leak from a facility 1, such as an industrial waste disposal site or a radioactive waste disposal site, located in an area where groundwater 2 exists, the leaked hazardous substances may become mixed into the groundwater 2. In this embodiment, in order to reduce the inflow of groundwater 2 contaminated with hazardous substances into rivers, lakes, oceans, areas where contamination should be avoided, and the like, a groundwater control facility 3 is provided upstream of these areas.

[0013] The groundwater control facility 3 comprises a borehole 4 provided in an area where groundwater 2 exists, an ion supply material 5 provided inside the borehole 4, and a sparingly soluble salt 6 generated from ions supplied from the ion supply material 5. The ion supply material 5 contains at least one of a first compound capable of generating cations that constitute the sparingly soluble salt 6 and a second compound capable of generating anions that constitute the sparingly soluble salt 6. Precipitation of the sparingly soluble salt 6 from the ions supplied from the ion supply material 5 inside and around the borehole 4 causes at least a portion of the flow path of the groundwater 2 inside and around the borehole 4 to be blocked, thereby reducing the flow rate of the groundwater 2 to a downstream area.

[0014] In the example of FIG. 1 , multiple boreholes 4 are provided at close intervals, and at least a portion of the sparingly soluble salts 6 precipitated between adjacent boreholes 4 combine to form a wall around the groundwater control equipment 3. This further reduces the flow rate of groundwater 2 downstream. Some of the groundwater, whose flow is obstructed by the wall, remains upstream, while some flows around the outside of the wall. Therefore, inside the groundwater control equipment 3, the flow rate of groundwater 2 decreases as sparingly soluble salts 6 are formed across the multiple boreholes 4, while outside the groundwater control equipment 3, the flow rate of groundwater 2 increases by the amount corresponding to the decrease inside the groundwater control equipment 3. Furthermore, the amount of groundwater 2 remaining upstream of the groundwater control equipment 3, including the wall, increases, while the amount of groundwater 2 remaining downstream decreases. The groundwater 2 blocked by the groundwater control equipment 3 may be pumped up and transported to a treatment facility for treating hazardous substances, or it may be directed to flow toward a treatment facility.

[0015] When the ion supply material 5 contains a first compound, cations that constitute a poorly soluble salt are eluted from the first compound, and when the ion supply material 5 contains a second compound, anions that constitute a poorly soluble salt are eluted from the second compound. When the ion supply material 5 contains both the first compound and the second compound, a poorly soluble salt is produced from the eluted cations and anions. When the ion supply material 5 contains the first compound, a poorly soluble salt is produced from the eluted cations and anions contained in the surrounding groundwater, etc. When the ion supply material 5 contains a second compound, a poorly soluble salt is produced from the eluted anions and cations contained in the surrounding groundwater, etc.

[0016] The ions supplied from the ion supply material 5 diffuse into voids and cracks in the bedrock and strata surrounding the borehole 4, forming sparingly soluble salt 6 in the voids and cracks around the borehole 4. This allows the sparingly soluble salt 6 to be blocked not only inside the borehole 4 but also in the voids around the borehole 4. As shown in Figure 1, by providing multiple boreholes 4 and blocking the voids between adjacent boreholes 4 with sparingly soluble salt 6, the surface including the multiple boreholes 4 can essentially function as a watertight wall. This makes it possible to effectively control the flow rate, flow velocity, flow direction, and retention amount of groundwater 2 while significantly reducing construction time and costs compared to installing a watertight wall underground.

[0017] The ions supplied from the ion supply material 5 diffuse according to the concentration gradient of the ions, but since the concentration of the ions originally present around the borehole 4 is usually low, the ions can easily diffuse to the voids and cracks in the bedrock surrounding the borehole 4 without the application of external force. Furthermore, since the ions diffuse in a dissolved state in water, they can easily diffuse into extremely tiny voids and cracks at the atomic or molecular level, even deep underground, regardless of pore water pressure, and form sparingly soluble salts 6 there to block them, thereby more reliably blocking the flow of groundwater 2 inside and around the borehole 4.

[0018] The width L (cm) of the reaction edge of the sparingly soluble salt 6 formed around the borehole 4, the velocity V (cm / s) at which the reaction edge is formed, and the diffusion coefficient D (cm 2 / s), the relationship D=VL holds. For example, if multiple boreholes 4 are set up at 20cm intervals, ion diffusion and sparingly soluble salt precipitation will progress from each borehole 4, and when the width of the reaction edge reaches approximately 10cm, the reaction edges from adjacent boreholes 4 will overlap. If the ion diffusion coefficient D around the borehole 4 is 10 -5~-6 cm 2 / s, it will take approximately several months to a year for the reaction edges from adjacent boreholes 4 to overlap. The spacing and arrangement pattern of the multiple boreholes 4 may be designed depending on the ion diffusion coefficient around the boreholes 4, the hydraulic conductivity, the flow rate and flow velocity of the groundwater 2, the period until the gaps between adjacent boreholes 4 are blocked, the purpose for which the groundwater control equipment 3 is installed, etc.

[0019] The sparingly soluble salt may be any salt that has sufficiently low solubility in water at the location where the borehole 4 is to be constructed, is chemically stable, and does not pollute the surrounding natural environment. For example, carbonates such as calcium carbonate, magnesium carbonate, and iron(II) carbonate (siderite, siderite), double salts such as calcium magnesium carbonate (CaMg(CO3)2, dolomite, dolomite), and sulfates such as calcium sulfate may be selected appropriately depending on the location where the borehole 4 is to be constructed. For example, calcium carbonate can be converted to calcium bicarbonate, which has a relatively high solubility in water, by chemical reaction with carbon dioxide. Therefore, if the borehole 4 is to be constructed in an environment with a relatively high carbon dioxide concentration, an ion supply material 5 may be provided in the borehole 4 to supply ions that form sparingly soluble salts other than calcium carbonate. Furthermore, since calcium carbonate can be dissolved by chemical reaction with acid, if the structural material is to be constructed in an environment with a relatively low pH, an ion supply material 5 may be provided in the borehole 4 to supply ions such as iron(III) ions, whose hydroxides and oxides are sparingly soluble in water. As a result, even if calcium carbonate in or around the borehole 4 is dissolved by acid present around the borehole 4, the calcium carbonate neutralizes the acid, raising the pH and causing sparingly soluble hydroxides and oxides to precipitate, which can block voids in or around the borehole 4. Ions for forming sparingly soluble hydroxides and oxides may be, for example, iron (III) ions, aluminum ions, copper (II) ions, zinc ions, manganese ions, etc.

[0020] When calcium carbonate is precipitated as a sparingly soluble salt, strontium, which is an alkaline earth metal like calcium and has similar chemical properties to calcium, is incorporated into the calcium carbonate. As a result, even if groundwater 2 contains radioactive isotopes of strontium, the calcium carbonate can be precipitated together with the calcium carbonate, thereby removing the radioactive isotopes of strontium from groundwater 2. Furthermore, by immobilizing other radioactive substances by co-precipitating them with sparingly soluble salt 6 or by adsorbing them to sparingly soluble salt 6, it is possible not only to prevent the diffusion of contaminated water containing radioactive substances but also to purify the contaminated water, the ground, or the surface of the earth.

[0021] When calcium carbonate is precipitated as a sparingly soluble salt, the first compound may be any compound capable of generating calcium ions, having sufficiently high solubility in water at the temperature of the environment in which the ion supply material is disposed, and not polluting the surrounding natural environment. The first compound may be, for example, calcium chloride (CaCl), calcium nitrate (Ca(NO), calcium bicarbonate (Ca(HCO), calcium oxide (CaO), etc.

[0022] When calcium carbonate is precipitated as a sparingly soluble salt, the second compound may be any compound capable of generating at least one of carbonate ions and bicarbonate ions, having sufficiently high solubility in water at the temperature of the environment in which the ion supply material is placed, and not polluting the surrounding natural environment. The second compound may be, for example, sodium bicarbonate (NaHCO3), potassium bicarbonate (KHCO3), ammonium bicarbonate (NH4HCO3), etc.

[0023] By placing the ion supply material 5 underground or on the ground surface, harmful ions contained in the ground or on the ground can be precipitated as insoluble salts, thereby purifying the ground or surface. For example, crushed gypsum board is sometimes spread on the ground to improve the ground. However, when calcium sulfate (CaSO4) contained in the gypsum dissolves and sulfate ions are released into the soil, they are converted into hydrogen sulfide by sulfate-reducing bacteria, causing corrosion of concrete and other materials. Furthermore, when the concentration of sulfate ions increases, sodium sulfate precipitates as a decahydrate (Na2SO4·10H2O: mirabilite) or anhydrous (Na2SO4: thenardite). However, the formation of a decahydrate generates a large expansion pressure, and the formation of a large amount of decahydrate in concrete or bricks can cause expansion failure. Furthermore, ettringite (3CaO·Al2O3·3CaSO4·32H2O), which is formed by the reaction of sulfates with an aluminate phase contained in cement, also has the property of expanding. Therefore, delayed formation of ettringite after cement hardens can cause expansion failure. Thus, sulfate ions are harmful ions that can cause deterioration of structures constructed with concrete and other materials. By providing an ion supply material 5 capable of supplying calcium ions in the soil, sulfate ions contained in the soil can be precipitated as calcium sulfate, thereby reducing the sulfate ions in the soil and purifying the soil. In this case, the first compound may be calcium chloride (CaCl2), calcium nitrate (Ca(NO3)2), calcium bicarbonate (Ca(HCO3)2), or the like. Furthermore, according to the technology of this embodiment, the concentration of harmful substances in the ground or on the ground surface, such as heavy metal ions and radioactive materials, can be reduced by precipitating, co-precipitating, or adsorbing them, thereby purifying the ground or surface.

[0024] Both the first compound and the second compound may be present together in the ion supply material 5. For example, the first compound and the second compound may be present mixedly in the ion supply material 5. Both the first compound and the second compound may be present separately in the ion supply material 5. For example, at least one of the first compound and the second compound may be enclosed in a capsule or the like and contained in the ion supply material 5. The capsule may be made of a material that dissolves in water or the like.

[0025] The ion supply material 5 may further include a matrix containing at least one of the first compound and the second compound. The matrix may be a material that has fluidity that allows it to be poured into the borehole 4 and hardens after injection through a chemical reaction such as hydration or polymerization, or through heating, cooling, drying, or exposure to light. The matrix may be, for example, cement, mortar, concrete, or a thermosetting resin such as an epoxy resin, a silicone compound, a polyol compound, or a phenolic compound, or a thermoplastic resin such as an acrylic resin, or a mixture thereof. The matrix may be a material that gradually releases at least one of the cations constituting the first compound and the anions constituting the second compound. For example, the matrix may be an epoxy resin. The ion supply material 5 in a solidified state may be inserted into the borehole 4.

[0026] The ion supply material 5 may include an ion exchange resin to which the ions to be supplied are adsorbed. In this case, the ion exchange resin can be selected or designed to release ions in an appropriate amount and supply rate depending on the type of ions to be supplied and the components, amount, pH, etc. of the chemical substances dissolved in the groundwater around the borehole 4.

[0027] The ion supply material 5 may include capsules that contain and gradually release the ions to be supplied. The ions contained in the capsules may be contained as a first compound or a second compound, or may be contained as an ion exchange resin to which the ions are adsorbed. In this case, too, the material, thickness, shape, etc. of the capsules can be selected or designed so as to release ions in an appropriate amount and supply rate depending on the type of ions to be supplied and the components, amounts, pH, etc. of the chemical substances dissolved in the groundwater surrounding the borehole 4.

[0028] The ion supply material 5 may contain a sparingly soluble material that serves as a nucleus for precipitating the sparingly soluble salt 6. This can promote the precipitation of the sparingly soluble salt 6. The sparingly soluble material may be any material that has sufficiently low solubility in water at the temperature of the borehole 4 in which the ion supply material 5 is provided, is chemically stable, and does not pollute the surrounding natural environment. For example, the sparingly soluble material may be a carbonate such as calcium carbonate, magnesium carbonate, or iron (II) carbonate (siderite, siderite), a double salt such as calcium magnesium carbonate (CaMg(CO3)2, dolomite, dolomite), a sulfate such as calcium sulfate, a metal hydroxide such as iron hydroxide, a metal such as iron, or a mineral such as sand or rock. The sparingly soluble material may be the same as or different from the sparingly soluble salt to be precipitated.

[0029] Even if voids or cracks occur in or around the borehole 4 due to external forces such as earthquakes, crustal movements, tidal currents, or typhoons after the poorly soluble salts 6 have precipitated and blocked the voids in or around the borehole 4, if ions supplied from the ion supply material 5 remain, the ions supplied from the ion supply material 5 will diffuse into the voids and cracks in or around the borehole 4, and the poorly soluble salts precipitated by reacting with the counterions can block the voids and cracks. As such, according to the technology of this embodiment, a self-repair function can be imparted to the groundwater control equipment 3, thereby improving the durability of the groundwater control equipment 3. It is desirable to design the ion supply material 5 so that ions supplied from the ion supply material 5 remain even after the voids in or around the borehole 4 have been blocked. In addition to the ion supply material 5 designed to supply the ions necessary to block voids in and around the borehole 4 immediately after the borehole 4 is placed, an ion supply material 5 containing ion-containing easily soluble salts or ion exchange resins in a container such as a capsule that will break and release its contents when an external force is applied that causes damage such as voids or cracks in or around the borehole 4 may be placed inside the borehole 4.

[0030] A pH adjuster may be installed inside the borehole 4 to increase the pH of the groundwater. If the groundwater 2 contains iron ions, as the pH of the groundwater 2 increases with the pH adjuster, the iron ions precipitate or colloidize in the form of α-, β-, γ-, or δ-iron oxyhydroxide, iron(III) oxide, iron(III) hydroxide, or the like, and are adsorbed onto the surface of the pH adjuster. This reduces the concentration of iron ions in the groundwater 2 and the flow rate of the groundwater 2. Iron oxides are known to co-precipitate heavy metal compounds and other compounds when they precipitate or colloidize. Therefore, the concentrations of not only iron ions but also heavy metal ions such as lead (Pb), cadmium (Cd), and arsenic (As) and light metal ions such as aluminum (Al) in the groundwater 2 can be reduced. Furthermore, it is known that alpha nuclides such as uranium form complexes and dissolve in water under acidic conditions but precipitate under alkaline conditions. Therefore, as the pH of the groundwater 2 is increased by the pH adjuster, the concentration of alpha nuclides such as uranium can be reduced. Similarly, the concentration of other harmful substances that dissolve in water under acidic conditions but precipitate under alkaline conditions can also be reduced. The pH adjuster may include at least one of calcium carbonate, calcium bicarbonate, calcium oxide, and calcium hydroxide. The pH adjuster may include concrete, cement, cement clinker, alite, belite, aluminate, ferrite, etc. The pH adjuster may be any compound whose aqueous solution is alkaline, such as sodium carbonate, sodium bicarbonate, sodium hydroxide, calcium acetate, or sodium acetate. The pH adjuster may be the same compound as the ion supply material 5, or a different compound. The pH adjuster may be provided inside a borehole 4 that has an ion supply material 5, or inside a borehole 4 that does not have an ion supply material 5. Multiple boreholes 4 may be provided, with some having an ion supply material 5 and others having a pH adjuster. When a compound that provides an alkaline aqueous solution is used as the ion supplying material 5, the ion supplying material 5 may also function as a pH adjusting material.

[0031] The borehole 4 may be provided to a depth that penetrates the permeable ground and reaches the less permeable ground. If there are existing boreholes or underground structures in the area where the groundwater 2 exists, and the ion supply material 5 is provided inside the borehole 4 or at the contact point between the underground structure and the ground, it is not necessary to provide a new borehole.

[0032] FIG. 2 shows a schematic diagram of another example of a groundwater control facility according to an embodiment. Groundwater control facility 3 is installed upstream of the downstream area of ​​groundwater 2 to reduce the inflow of groundwater 2 contaminated with hazardous substances leaked from facility 1 located in an area where groundwater 2 exists into a downstream area. In this example, multiple boreholes 4 are installed at wider intervals than in the example shown in FIG. 1, and the sparingly soluble salts 6 are not integrated. Again, the flow rate of groundwater 2 decreases inside groundwater control facility 3 and increases outside. Furthermore, the amount of groundwater 2 stored increases upstream of groundwater control facility 3 and decreases downstream. This reduces the contamination of rivers, soil, and other areas downstream of the groundwater.

[0033] FIG. 3 shows a schematic diagram of another example of a groundwater control system according to an embodiment. When the foundation ground of a levee body 11 constituting a river levee 10 is highly permeable, rainwater or river water may seep into the foundation ground, potentially causing leaks or piping problems. Installing a groundwater control system 3 in the foundation ground can prevent rainwater or river water from seeping into the foundation ground. Inside the groundwater control system 3, the flow rate of groundwater 2, which has been infiltrated by rainwater or river water, decreases, while outside the groundwater control system 3, the flow rate of groundwater 2 increases. Furthermore, the amount of groundwater 2 retained on the river side of the groundwater control system 3 increases, while the amount of groundwater 2 retained on the land side decreases. Furthermore, by providing an ion supply material 12 on the surface of the levee body 11 and precipitating sparingly soluble salt 13 on the surface of the levee body 11, the infiltration of rainwater or river water into the levee body 11 can be prevented. This improves the strength and durability of the levee 10.

[0034] FIG. 4 schematically illustrates the configuration of another example of a groundwater control system according to an embodiment. When a pollution source 7 containing harmful substances is present in an area where groundwater 2 exists, groundwater control system 3 is installed upstream of the pollution source 7 to reduce the inflow of groundwater 2 into the pollution source 7. The groundwater control system 3 changes the flow direction of groundwater 2 to bypass the pollution source 7. The flow rate of groundwater 2 decreases inside the groundwater control system 3 and increases outside the groundwater control system 3. The amount of groundwater 2 stored increases upstream of the groundwater control system 3 and decreases downstream. This reduces contamination of groundwater 2. Similarly, when a weak area with loose ground, such as an embankment, exists in the area where groundwater 2 exists, groundwater control system 3 is installed upstream of the weak area to reduce the inflow of groundwater 2 into the weak area. This reduces the risk of the weak area collapsing due to the infiltration of groundwater 2, causing a landslide.

[0035] FIG. 5 shows a schematic diagram of another example of a groundwater control system according to an embodiment. When a pollution source 7 containing hazardous substances, such as industrial waste, is disposed in an area where groundwater 2 exists, groundwater control system 3 is installed around the pollution source 7 to reduce the inflow of groundwater 2 into the pollution source 7 and the outflow of groundwater 2 from the pollution source 7. The groundwater control system 3 changes the flow direction of groundwater 2 to bypass the pollution source 7. The flow rate of groundwater 2 decreases inside the groundwater control system 3 and increases outside the groundwater control system 3. Furthermore, the amount of groundwater 2 remaining from the pollution source 7 increases inside the area surrounded by the groundwater control system 3, while the amount of groundwater 2 remaining from the pollution source 7 decreases downstream of the groundwater control system 3. This configuration prevents contaminated groundwater 2 from flowing into downstream areas and prevents the pollution source 7 from collapsing due to the infiltration of groundwater 2, resulting in landslides.

[0036] FIG. 6 shows a schematic diagram of another example of a groundwater control system according to an embodiment. When a pollution source 7 containing hazardous substances, such as industrial waste, is disposed in an area where groundwater 2 exists, groundwater control system 3 is installed along a flow path that directs the groundwater 2 to avoid the pollution source 7. The groundwater control system 3 changes the flow direction of the groundwater 2 to bypass the pollution source 7. The flow rate of the groundwater 2 decreases inside the groundwater control system 3 and increases outside the system. The amount of groundwater 2 stored around the pollution source 7 located inside the system surrounded by the groundwater control system 3 decreases, and the amount of groundwater 2 stored downstream of the system decreases. This prevents the inflow of contaminated groundwater 2 into downstream areas and prevents the pollution source 7 from collapsing due to the infiltration of groundwater 2, resulting in landslides.

[0037] 7 is a schematic diagram showing the configuration of another example of a groundwater control facility according to an embodiment. When an underground structure 8 under construction exists in an area where groundwater 2 exists, groundwater control facility 3 is provided upstream of the underground structure 8 in order to reduce the inflow of groundwater 2 into the underground structure 8. Inside the groundwater control facility 3, the flow rate of groundwater 2 decreases, while outside the facility, the flow rate of groundwater 2 increases. Furthermore, the amount of groundwater 2 that remains increases upstream of the groundwater control facility 3, while the amount of groundwater 2 that remains decreases downstream. This makes it possible to prevent groundwater 2 from interfering with the construction of the underground structure 8.

[0038] FIG. 8 shows a schematic configuration of another example of a groundwater control facility according to an embodiment. When a dam 9 is present in an area where groundwater 2 exists, groundwater control facility 3 is provided along a flow path for causing groundwater 2 to flow into the dam 9. The groundwater control facility 3 changes the flow direction of the groundwater 2 toward the dam 9. The flow rate of the groundwater 2 decreases inside the groundwater control facility 3, and increases outside the groundwater control facility 3. In addition, the amount of groundwater 2 stored increases around the dam 9 located between the groundwater control facilities 3, and the amount of groundwater 2 stored decreases on the opposite side of the dam 9 across the groundwater control facility 3. This allows the groundwater 2 to be guided to the area around the dam 9.

[0039] Figure 9 shows a schematic diagram of another example of the configuration of a groundwater control facility according to an embodiment. Groundwater control facility 3 is installed in advance in ground that is expected to liquefy in the event of an earthquake or other event. As poorly soluble salt 6 precipitates and increases in volume, it compresses the surrounding gravel, and the gaps between the gravel are blocked by poorly soluble salt 6, expelling groundwater that had accumulated in the gaps between the gravel and reducing the amount of accumulated groundwater. This strengthens the ground.

[0040] Figure 10 shows a schematic diagram of another example of the configuration of a groundwater control facility according to an embodiment. Groundwater control facility 3 is installed in advance in loose ground that is prone to collapse. In this case, too, the sparingly soluble salt 6 precipitates and increases in volume, compressing the surrounding gravel. The sparingly soluble salt 6 then blocks the gaps in the gravel, expelling groundwater that had accumulated in the gaps, thereby reducing the amount of accumulated groundwater. This strengthens the ground and helps prevent landslides.

[0041] FIG. 11 shows a schematic diagram of another example of the configuration of a groundwater control facility according to an embodiment. Before constructing an underground structure 8, a groundwater control facility 3 is installed in advance in ground with a high water content. As poorly soluble salts 6 precipitate and increase in volume, the surrounding gravel is compressed, and the gaps between the gravel are blocked by the poorly soluble salts 6, driving out groundwater that had been accumulating in the gaps between the gravel and reducing the amount of accumulation. This allows the underground structure 8 to be constructed on reinforced ground, thereby improving the strength and durability of the underground structure 8.

[0042] Figure 12 is a flowchart showing the steps of a control method according to an embodiment. A borehole 4 is provided in an area where water is present underground and / or on the surface of the earth (S10). An ion supply material 5 is provided inside the borehole 4 (S12). A poorly soluble salt 6 is precipitated from ions supplied from the ion supply material 5 inside and around the borehole 4 (S14). Voids inside and around the borehole 4 are blocked by the poorly soluble salt 6, and the flow rate, flow velocity, flow direction, retention amount, etc. of water present underground and / or on the surface of the earth are changed.

[0043] FIG. 13 is a flowchart showing the steps of a method for repairing groundwater control equipment according to an embodiment. After the installation of the groundwater control equipment 3, an investigation of the groundwater flow rate, flow velocity, flow direction, and retention volume reveals that the groundwater control by the groundwater control equipment 3 is insufficient, or that voids or cracks have occurred in the poorly soluble salt 6 of the groundwater control equipment 3. If this reveals, the groundwater control equipment 3 is repaired. An ion supply material 5 is added to the inside of the borehole 4 (S20). A new borehole 4 is also created near the existing borehole 4 (S22), and an ion supply material 5 is installed inside the new borehole 4 (S24). The poorly soluble salt 6 precipitates from ions supplied by the newly installed ion supply material 5 (S26). The voids inside and around the borehole 4 are blocked by the poorly soluble salt 6, changing the groundwater flow rate, flow velocity, flow direction, retention volume, etc. One or both of S20, S22, and S24 may be performed.

[0044] The present disclosure has been described above based on examples. These examples are merely illustrative, and it will be understood by those skilled in the art that various modifications are possible in the combination of the components and processing steps, and that such modifications are also within the scope of the present disclosure.

[0045] In the embodiment, a poorly soluble salt is precipitated around a poorly soluble material, but a poorly soluble compound other than salt may also be precipitated. In this case, the ion supply material may contain a compound that is easily soluble in water but reacts chemically with other compounds present in the environment where the ion supply material is placed to produce a poorly soluble precipitate. For example, an ion supply material constituting an underground structure near a volcano may contain a compound that generates zinc ions, and zinc sulfide may be precipitated by reacting with hydrogen sulfide present in the surrounding area.

[0046] An outline of one aspect of the present disclosure is as follows.

[0047] The control method of the present disclosure includes the steps of providing an ion supply material containing at least one of a first compound capable of generating cations constituting a poorly soluble salt and a second compound capable of generating an anion constituting a poorly soluble salt in an area where water exists underground or on the earth's surface, and precipitating the poorly soluble salt around the ion supply material, thereby changing at least one of the flow rate, flow direction, and retention amount of water. This allows for appropriate control of water existing underground or on the earth's surface, thereby preventing disasters, pollution, and the like. Furthermore, since water existing underground or on the earth's surface can be controlled using a simpler method, construction time and costs can be reduced. The ion supply material may be provided underground, such as in soil, ground, bedrock, or the seabed where groundwater exists, or on the earth's surface or in contact with river water, seawater, or the like.

[0048] The control method further includes a step of providing a hole in the above-mentioned region, and the step of providing an ion supply material includes a step of providing the ion supply material inside the hole, and at least one of the flow rate, flow direction, and retention amount of water inside and around the hole may be changed by precipitating sparingly soluble salt inside and around the hole. This makes it possible to appropriately control water present underground or on the surface of the earth and prevent the occurrence of disasters, pollution, etc. In this disclosure, the term "hole" includes a hole with a bottom. Furthermore, "providing" an ion supply material includes "filling," "injecting," "putting," "inserting," "encapsulating," etc., depending on the form of the ion supply material.

[0049] The ion supplying material may be provided upstream of an area where the inflow of water should be reduced. The ion supplying material may be provided downstream of an area where the outflow of water should be reduced. The ion supplying material may be provided along a flow path that guides water. This makes it possible to appropriately control water present underground or on the surface of the earth, thereby preventing disasters, pollution, and the like.

[0050] The ion supply materials may be present at multiple locations in the above-mentioned region, and at least one of the flow rate, flow direction, and retention amount of water may be changed by precipitating poorly soluble salts between adjacent ion supply materials. This allows for appropriate control of water present underground and on the surface, thereby preventing the occurrence of disasters, pollution, and the like.

[0051] At least a portion of the poorly soluble salt precipitated between adjacent ion supply materials may be integrated to form a wall, which can further change at least one of the flow rate, flow direction, and retention amount of water present underground or on the ground surface.

[0052] A plurality of holes may be provided, and the spacing between the holes may be determined based on the diffusion coefficient of at least one of cations and anions at the locations where the plurality of holes are provided. This allows for appropriate control of water present underground and on the surface of the earth, and also reduces construction time and costs.

[0053] The spacing between multiple holes is determined by the width L (cm) of the reaction edge of the sparingly soluble salt formed around the hole, the speed V (cm / s) at which the reaction edge forms, and the diffusion coefficient D (cm 2 / s) based on the relationship D=VL. This allows for appropriate control of water present underground and on the surface, and also reduces construction time and costs.

[0054] The hardly soluble salt may be calcium carbonate, which can reduce material costs and improve the durability of equipment for controlling water present underground or on the ground surface.

[0055] When calcium carbonate precipitates, it may take in strontium contained in the water, thereby reducing the radioactive isotopes of strontium contained in water present underground or on the surface of the earth.

[0056] The ion supply material may include a base material and at least one of a first compound and a second compound mixed into the base material, thereby reducing the construction time and costs.

[0057] The base material may contain an epoxy resin, which allows the first compound and the second compound mixed in the base material to gradually release ions, thereby more reliably sealing off voids inside and around the borehole 4.

[0058] A pH adjuster may be placed inside the hole to increase the pH of the water, thereby reducing the iron ions and heavy metal ions contained in water underground and on the surface of the earth.

[0059] The reinforcement method of the present disclosure includes the steps of providing an ion supply material containing at least one of a first compound capable of generating cations constituting poorly soluble salts and a second compound capable of generating anions constituting poorly soluble salts in at least one of the underground and the earth's surface, and reinforcing at least one of the underground and the earth's surface by precipitating poorly soluble salts around the ion supply material. This allows the underground and the earth's surface to be appropriately reinforced and the occurrence of disasters and the like to be reduced. It also reduces construction time and costs.

[0060] The purification method of the present disclosure includes the steps of providing an ion supply material containing at least one of a first compound capable of generating cations that constitute poorly soluble salts and a second compound capable of generating anions that constitute poorly soluble salts, in at least one of the underground and the surface of the earth, and reducing harmful ions by generating poorly soluble salts with cations or anions and precipitating them. This allows for appropriate purification of the underground and the surface of the earth, preventing disasters and pollution, and reducing construction time and costs.

[0061] The harmful ions may be sulfate ions, which can prevent corrosion of concrete and improve durability.

[0062] The structure of the present disclosure includes an ion supply material present in an area where water exists underground or on the surface of the earth, and the ion supply material contains at least one of a first compound capable of generating cations that constitute a poorly soluble salt and a second compound capable of generating anions that constitute a poorly soluble salt, and poorly soluble salt present around the ion supply material. This allows for appropriate control of water present underground or on the surface of the earth, thereby preventing disasters, pollution, and the like. Furthermore, since water present underground or on the surface of the earth can be controlled using a simpler method, construction time and costs can be reduced.

[0063] The ion supply material may be present inside the holes present in the above-mentioned region. This allows for appropriate control of water present underground or on the surface of the earth, thereby preventing disasters, pollution, and the like. Furthermore, since water present underground or on the surface of the earth can be controlled using a simpler method, construction time and costs can be reduced.

[0064] The method for repairing a workpiece according to the present disclosure includes adding an ion supplying material near the hardly soluble salt, thereby improving the durability of the equipment for controlling water present underground or on the ground surface and enabling appropriate control of water present underground or on the ground surface over the long term.

[0065] The method for repairing a workpiece according to the present disclosure includes the steps of providing a new hole near the existing hole and providing an ion supply material inside the new hole, thereby improving the durability of the equipment for controlling water present underground or on the ground surface and enabling appropriate control of water present underground or on the ground surface over the long term. [Explanation of symbols]

[0066] 1 Facility, 2 Groundwater, 3 Groundwater control facility, 4 Borehole, 5 Ion supply material, 6 Difficulty soluble salt, 7 Contamination source, 8 Underground structure, 9 Dam, 10 Levee, 11 Levee body, 12 Ion supply material, 13 Difficulty soluble salt.

Claims

1. providing an ion supplying material containing at least one of a first compound capable of generating cations constituting a poorly soluble salt and a second compound capable of generating an anion constituting the poorly soluble salt in a region where water flows in at least one of the underground and the surface of the earth; a step of reducing a flow rate of the water downstream of the ion supply material by precipitating the poorly soluble salt around the ion supply material; A control method comprising:

2. At least a part of the region through which the water flows is blocked by the hardly soluble salt precipitated around the ion supply material, and the flow rate of the water downstream of the region blocked by the hardly soluble salt is reduced. The control method according to claim 1 .

3. A part of the water whose flow is obstructed by the hardly soluble salt remains upstream of the region blocked by the hardly soluble salt, or flows around to the outside of the region blocked by the hardly soluble salt. The control method according to claim 1 or 2.

4. providing holes in the region; providing the ion supply material includes providing the ion supply material within the hole; The hardly soluble salt is precipitated inside and around the holes, thereby reducing the flow rate of water inside and around the holes. The control method according to any one of claims 1 to 3.

5. The ion supply material is present at a plurality of locations in the region, and the hardly soluble salt precipitates between adjacent ion supply materials, thereby reducing the flow rate of the water downstream of the plurality of ion supply materials. The control method according to claim 4.

6. At least a portion of the hardly soluble salt precipitated between adjacent ion donors is integrated to form a wall. The control method according to claim 5.

7. A plurality of the holes are provided, The intervals between the plurality of holes are determined based on the diffusion coefficient of at least one of the cations and the anions at the locations where the plurality of holes are provided. The control method according to any one of claims 4 to 6.

8. The intervals between the plurality of holes are determined by the width L (cm) of the reaction edge of the hardly soluble salt formed around the hole, the speed V (cm / s) at which the reaction edge is formed, and the diffusion coefficient D (cm ２ / s) is determined based on the relationship D = VL The control method according to claim 7.

9. A pH adjuster is provided inside the hole to increase the pH of the groundwater. The control method according to any one of claims 4 to 8.

10. the poorly soluble salt is calcium carbonate, When calcium carbonate precipitates, it takes in the strontium contained in the water. A control method according to any one of claims 1 to 9.

11. The ion supply material includes a base material and at least one of the first compound and the second compound mixed in the base material. A control method according to any one of claims 1 to 10.

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