JP5360578B2 - Ground injection method - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a ground injection method, and more particularly, a ground injection method that places little load on the environment by injecting a grout having a specific component through a buried injection pipe mainly composed of a biodegradable plastic. About.

  In recent years, filling rock cracks in dams, subsurface dams, tunnels, etc., as well as containment of radioactive waste in underground cavities and storage in underground cavities such as LPG, has become an important national issue. It has become.

  In addition, for tunnel excavation under high osmotic pressure, deep underground development, or construction of a dam or underground dam water stop, and in recent years containment of radioactive waste rock cavities, and storage of liquefied propane gas rock cavities In the construction of water-sealed underground bedrock tanks, etc., ground injection with excellent strength and water-stopping effect in grouting is required. In particular, when excavation work or deep underground development under high water pressure takes a long time, or when building a rock cavity or forming a still water layer around the cavity, the gel cracks are filled with a wide range of gelled materials. Therefore, long-term water-stop and long-term strength durability are required. If these problems are resolved, not only the safety of excavation work under pressure, but also the prevention of the formation of a water-stopping layer, leakage of harmful substances to the surroundings, penetration of the cavity from the outside, groundwater in the surrounding ground Drop and ground deformation are suppressed, and repair costs such as water leakage after installation are reduced.

  Generally, various solution-type silica grouts made from water glass are known as grouts used for ground improvement such as soft ground and sand ground. For example, water glass alkaline grout, grout based on acidic silica sol, grout based on active silica obtained by treating water glass with a cation exchange resin or ion exchange membrane, and active silica are concentrated and granulated. A weakly alkaline and stable silica colloid having a pH of 9 to 10.

  In addition, due to the growing interest in the environment, in the field of ground improvement, there is a need for technology that has as little impact on the environment around the construction site as possible. Specifically, the outflow and retention of harmful substances in groundwater, soil, etc. Development of construction methods with no residual material after construction is underway. For example, in the present applicants etc., a ground injection method using a ground injection device that is decomposed by microorganisms present in the ground after construction (see Patent Document 1), a grout that can be consolidated without using strong alkalis or strong acids. Is disclosed (see Patent Document 2).

Japanese Patent No. 3406567 JP 2008-161778 A

  However, in the grout described in Patent Documents 1 and 2, consideration is not given to the surrounding environment such as microorganisms, vegetation, and groundwater in the soil. Moreover, although the method of the said patent document 3 can prevent a buried pipe from remaining in the ground for a long time after construction, since the grout similar to the conventional construction method is used, it is soiled by a strong alkali or a strong acid. May adversely affect Further, the method described in Patent Document 4 can prevent the generation of harmful substances derived from grout even in the vicinity of the improved ground or after the ground improvement, but the plastic constituting the buried pipe is difficult to be decomposed and the cost is reduced. Therefore, if left without being removed after construction, substances such as components for synthesizing plastics, additives, etc. may elute to the surroundings, which may cause soil and groundwater contamination.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems in the prior art and to provide a ground injection method that places little load on the environment.

  As a result of intensive studies to solve the above problems, the present inventor conducted a ground treatment using a grout containing a specific component through an embedded injection tube having a biodegradable plastic as a main component, The inventors have found that the use and generation of harmful substances can be suppressed, and that the load on the environment around the construction site can be reduced, and the present invention has been completed.

That is, the ground injection method according to the present invention is a method in which the ground is injected through an embedded injection pipe mainly composed of a biodegradable plastic made of polylactic acid or (polylactic acid / polybutylene succinate system) block copolymer embedded in the ground. In the method of injecting an injection material, a yeast that can be added to food, or a yeast that can be added to food and a nutrient source of the yeast, and further a grout containing a silica compound is injected into the ground, or A sealing material containing a yeast compound that can be added, or a yeast that can be added to the food and a nutrient source of the yeast, and further containing a silica compound is filled around the injection tube.
In addition, the ground injection method of the present invention includes a ground injection pipe embedded in the ground, and embedded in an underground injection pipe mainly composed of a biodegradable plastic made of polylactic acid or (polylactic acid / polybutylene succinate system) block copolymer. In the method of injecting the injection material, a yeast that can be added to food, or a yeast that can be added to food and a nutrient source of the yeast, and a grout containing calcium salt is injected into the ground, or A sealing material containing a yeast that can be added, or a yeast that can be added to the food and a nutrient source for the yeast, and further containing a calcium salt is filled around the injection tube.

  In the ground injection method of the present invention, the grout preferably further contains a silica compound, and the grout further preferably contains a calcium salt.

  Furthermore, in the ground injection method of the present invention, the nutrient source is preferably sugar, and after injecting the grout into the ground, a material containing microorganisms that decompose the biodegradable plastic is added to the biodegradable plastic. It is preferable to fill. In the ground injection method of the present invention, it is preferable to inject the grout into contaminated soil, and it is preferable to inject carbon dioxide. In the ground injection method of the present invention, the biodegradable plastic is preferably an aliphatic polyester resin composition.

  According to the present invention, it is not necessary to use a grout containing harmful chemicals such as strong alkalis and strong acids, and even if the buried pipe used for ground injection is left in the ground after construction, it is decomposed into harmless substances by microorganisms etc. As a result, it has become possible to provide a ground injection method with less adverse effects on the environment. In particular, by adding microorganisms that can degrade biodegradable plastics, which are the main components of buried injection pipes, to the grout, after the grout is injected, microorganisms contained in the grout also decompose the buried injection pipes. It has become possible to disassemble the buried injection pipe much faster than if the buried injection pipe is simply left in the ground. As a result, the time until the disappearance of unnecessary debris after the ground injection method has been completed has been greatly shortened, and the load on the environment can be further reduced. In addition, by using a grout containing the nutrient source of the microorganism, microorganisms capable of degrading biodegradable plastics existing in the ground increase through the use of the nutrient source, the decomposition of the buried injection tube is promoted, In the same way, it becomes possible to disassemble the buried injection pipe more quickly, and the time until unnecessary debris disappears after the construction method is greatly shortened, and the burden on the environment can be reduced. It was.

FIG. 1 is an explanatory diagram of an embedding test of an injection tube according to the present invention. FIG. 2 is an explanatory view of a specific example of an injection device for injection material according to the present invention. FIG. 3 is an explanatory diagram of a specific example in which the present invention is implemented as a hole wall protective material or an injection material.

Hereinafter, embodiments of the present invention will be specifically described.
The biodegradable plastic, which is the main constituent of the buried injection pipe used in the present invention, is composed of a polymer compound that is decomposed by microorganisms, and is preferably thermoplastic and processed by a conventionally known method. It has a mechanical strength as an embedded injection pipe. Even if it is left in the ground after construction, it will not be decomposed by the microorganisms in the ground and will not remain, so there will be no load on the surrounding environment. In addition, no harmful gas is generated when burned.

  Examples of the biodegradable plastic include resins having a structure in which the main chain is aliphatic and having an ether bond or an ester bond, and those having a hydroxyl group or a carboxyl group in the main chain or side chain. Specifically, polyhydroxybutyrate / valerate (PHB / V), starch / polycaprolactone, polyhydroxybutyrate, poly (hydroxybutyrate / hydroxyhexanoate), esterified starch, cellulose acetate, chitosan / cellulose / Starch, starch / chemically synthesized green plastic, polylactic acid, (polylactic acid / polybutylene succinate) block copolymer, polycaprolactone, poly (caprolactone / butylene succinate), polybutylene succinate, poly (butylene succinate / adipate ), Poly (butylene succinate / carbonate), poly (ethylene terephthalate / succinate), poly (butylene adipate / terephthalate), poly (tetramethylene adipate / terephthalate), polyethylene Kushineto, polyvinyl alcohol, poly glycolic acid. These may be used two or more of these. Other examples of biodegradable plastics that can be applied to the buried injection pipe of the present invention include Cell Green (manufactured by Daicel Chemical Co., Ltd.), Bionore (Showa Denko Co., Ltd., Showa Polymer). Co., Ltd.), Rakuti (manufactured by Shimadzu Corporation), Poval (manufactured by Kuraray Co., Ltd.), Wonder Starken (manufactured by Wonder Co., Ltd.), Biomax (manufactured by DuPont), Ecoflex (manufactured by BASF), etc. There is.

  The thicker the buried injection pipe, the longer the degradation time by microorganisms in the ground. Moreover, the injection ground is under various conditions such as acidity to alkaline, seawater infiltration, and the decomposition time of the buried injection pipe varies depending on the type of the infusate. Is preferably decomposed.

  The buried injection pipe used in the method of the present invention can also promote degradation or degradation of strength by lowering the weather resistance as necessary, especially when using such a buried injection pipe. Pay attention to the storage and management of the buried injection pipe before construction, for example, it is preferable to avoid exposure to direct sunlight for a long time or leaving it in the rain as much as possible. Moreover, you may make it easy to grind | pulverize an embedding injection pipe using a cellulose fiber as a structural component of the embedding injection pipe used for this invention. Examples of the cellulose fiber include waste paper, wood powder, hemp, cotton pulp, and wood pulp.

  The grout used in the ground injection method of the present invention contains microorganisms or a nutrient source of microorganisms or both, and other ingredients are the same as those conventionally known as long as they do not adversely affect the environment. be able to. The nutrient source is decomposed into ethanol and carbon dioxide by the metabolism of microorganisms added from the outside or the microorganisms originally present in the ground, so that the ground can be improved without using large equipment and chemicals. The impact on the surrounding environment is small.

  That is, for example, when a silica compound and microorganisms or microorganism nutrients or both are injected into the ground, microorganisms added from the outside or microorganisms originally present in the ground metabolize to release carbon dioxide, and the carbon dioxide Lowers the pH of the grout. The silica compound then gels and solidifies between the soil particles to improve the ground. Alcohols also have the ability to gel silica solutions such as water glass.

  As silica compounds, in addition to water glass, ion exchange resins or ion exchange membranes are used to remove the alkali content in water glass, and the acid radicals and alkali metals of acid water glass are ion exchanged. Resin, active silica obtained by removing with an ion exchange membrane, colloidal silica obtained by concentrating active silica and granulating, or a silica solution in which water glass is mixed may be used. By using these, gelation can be ensured. Moreover, the time required for gelation can also be shortened by using a colloidal product obtained by adding a small amount of acid to water glass. Moreover, the grout which mixed the fine particle bubble in water or a silica solution like microbubble grout can also be used. Moreover, the activated silica can be stabilized with water glass or caustic soda, left standing for one week and aged to form a colloid.

  Furthermore, by injecting microorganisms and organic substances simultaneously, or when constructing in the ground where many microorganisms exist, injecting organic substances into the ground controls the respiration rate, metabolism amount, that is, carbon dioxide generation amount of microorganisms. In addition, gelation of the silica compound can be promoted or adjusted.

  In addition, by simultaneously injecting a gas such as carbon dioxide or oxygen, it is possible to adjust the metabolic rate of microorganisms to promote or regulate gelation.

  The gelation time can also be adjusted by adding a gel compound that has little influence on microorganisms as a gelation accelerator or regulator for the silica compound. Examples include inorganic salts such as potassium chloride and sodium chloride, trace amounts of acids, and organic salts. In addition, by adding polyvalent metal compounds such as calcium compounds and magnesium compounds, carbon dioxide gas released by the metabolism of microorganisms reacts with polyvalent metal compounds to form insoluble polyvalent metal carbonates, and the gelation time Not only can be adjusted, but also the strength of the injection material can be increased. Moreover, since it is necessary to adjust to pH which microorganisms activate, you may use a small amount of pH adjusters.

The sealing material used in the present invention fills the hole around the injection hole and the space around the injection pipe, and is strong enough to be destroyed by the injection pressure of the injection liquid from the injection port of the injection pipe (50 to 100 kN / m). Suspensions of about ² are preferred, and specific examples include cements such as portland cement, low alkali cement, fly ash cement, etc., which are low in leasing, clays such as bentonite, inorganic sulfates such as calcium aluminate, gypsum and sodium sulfate. , Slag, lime, fibers, cellulose, polymer compounds such as CMC, polysaccharides, etc. These combinations are mixed with microorganisms and nutrient sources.

  Any microorganism can be used as long as it is capable of degrading the biodegradable plastic, which is the main component of the buried infusion tube used in the present invention, and hardly affects the human body and the environment. is there. In particular, those used in conventional foods such as lactic acid bacteria, natto bacteria, baker's yeast and brewer's yeast, those that are abundant in general ground, Staphylococcus bacteria, Penibacillus bacteria, Bacillus bacteria, Actinomyces bacteria such as Actinomyces bacteria, Amycolatopsis genus actinomycetes, Saccharomycus genus actinomycetes, Actinomadura genus actinomycetes, Streptomyces genus actinomycetes, and the like can also be used. As microorganisms activated in the ground, fermentative bacteria and spoilage bacteria that are facultative anaerobic bacteria that do not need to send air by explosion or agitation can be used. Alternatively, soil and sand from the field may be collected and the mixed solution or the supernatant thereof may be used. In metabolism by lactic acid bacteria, lactic acid is produced to lower pH and promote or regulate gelation.

  As microorganisms capable of degrading biodegradable plastics, microorganisms that inhabit plant leaves are effective and preferable. Any of fungi and bacteria may be used, typically yeast, filamentous fungus, and bacteria. Examples of yeasts that can inhabit the leaf surface include the genus Pseudozyma (P.antarctica, P.ruglosa, P.parantarctica, P.aphidis, etc.) and Cryptococcus (Cryptococcus laurenti, Cryptococcus flavus, etc.), others, Rhodotorula glutinis, Rhodotorulamuci Sakaguchia dacryoidea, Sporidiobolus pararpseus and Ustilago maydis are known. Among the above yeasts, yeasts belonging to the genus Pseudozyma or Cryptococcus are preferred. Examples include yeasts of Pseudozyma antarctica JCM3941, Pseudozyma antarctica JCM10317, Pseudozyma antarctica JCM3941, Pseudozyma ruglosaJCM10323 and Pseudozymaparantarctica JCM11752, Pseudozyma antarcticaJCM10317 and Pseudozymaant 117 are particularly preferred. Examples of the filamentous fungi include, for example, Acremonium genus, Alternaria genus, Arthrinium genus, Aspergillus genus, Aureobasidium genus, Cladosporium genus, Epicocumcum genus, Exophiala genus, Fusarium genus, Leptosphaeria genus, Paecilomyces genus, Penicillium genus, Phoma genus, Trichoderma genus, Examples include Pseudotaeniolina genus, Ulocladium genus, Phaeosphaeriopsis genus, and Galactomyces genus filamentous fungi. Among them, Cladosporium genus, Penicillium genus, Leptosphaeria genus and Alternaria genus filamentous fungi are preferable. For example, Alternaria alternata, Cladosporium cladosporioides, Cladosporium oxysporum, Penicilliumpinophilum filamentous fungi are particularly preferred.

  Currently, the method of injecting nutrients in the local contaminated ground, growing the microorganisms in the soil, and decomposing the pollutants is used, so that microorganisms with the desired resolution are isolated from the microorganisms collected from the field. It can also be cultured and used.

  The nutrient source for microorganisms used in the ground injection method of the present invention is a saccharide that is metabolized by microorganisms, and is preferably a saccharide that is metabolized and decomposed by microorganisms in the soil. Examples include monosaccharides such as glucose and fructose, disaccharides such as sucrose, maltose and galactose, other oligosaccharides, polysaccharides such as starch and maltodextrin, and other saccharides.

  In addition, by using a reaction product of water glass such as glyoxal or organic acid esters such as carbonic acid and acetic acid as nutrients, the reaction product after gelation of water glass can be used as a nutrient source for microorganisms. Can help to break down.

  Since the metabolic rate varies depending on the microorganism or organic nutrient source, it is necessary to select the soil according to the construction site.

  Examples of the polyvalent metal compound include calcium salts such as calcium chloride, polyvalent metal salts such as magnesium chloride, calcium hydroxide, and the like, fine particle lime, fine particle cement, fine particle slag, gypsum, calcium carbonate, and the like. In addition, calcium such as shells contained in the ground, lime, etc. also affect the reaction. In the present invention, the combined use of silica and calcium brings about an increase in strength due to the formation of calcium silicate.

  In the present invention, the infusion solution of the present invention is infiltrated, mixed, or covered with soil or waste containing harmful substances to prevent diffusion of contaminated areas from harmful substances and waste, and microorganisms in the infused liquid, Alternatively, the ground can be limited and purified by injecting a microorganism or soil purification material, which is effective.

  The hazardous substances in the present invention are heavy metals such as hexavalent chromium, mercury, lead and cadmium, waste mud generated by civil engineering, incinerated ash, sludge, industrial waste, environmental hormones, agricultural chemical residues, organic solvents, organic Organic compounds such as detergents, and ground containing harmful substances that adversely affect the human body and the environment such as dioxins. Examples include alkylmercury, total mercury, cadmium, lead, organic phosphorus, hexavalent chromium, arsenic, cyanide, PCB, trichlorethylene. , Tetrachloroethylene, dichloromethane, carbon tetrachloride, 1,2-dichloroethane, 1,1-dichloroethylene, cis-1,2-dichloroethylene, 1,1,1-trichloroethane, 1,1,2-trichloroethane, 1,3-dichloro Examples include propene, thiuram, simazine, thiobencarb, benzene, selenium and the like.

  An example of decomposition by microorganisms is as follows.

  Organic matter in industrial waste is decomposed by microorganisms such as bacteria and filamentous gold fungi. Ammonia involved in the production of trihalomethane, which is a carcinogen, is decomposed by nitrifying bacteria, and industrial solvent trichlorethylene is decomposed by ammonia oxidizing bacteria. In addition, agricultural chemicals are decomposed by filamentous fungi, bacteria, and radioactive bacteria in the soil.

  For example, parathion is degraded by the collaboration of Pseudomonas stuzeri and Pseudomonasaeruginosa. Carbamate insecticides are degraded by Penicillium and Trichoderma. Furthermore, PCB is decomposed by Pseudomonas and Alcaligenes, and chlorobenzene is also decomposed by Pseudomonas. Of course, these microorganisms and fungi can be used in the present invention.

  Further, in the present invention, when silica is not used, calcium carbonate is deposited between the soil particles to give water tightness, but water permeability is lowered. However, since gelation is not accompanied, injection is repeated many times. The water-stopping property can be improved. However, when silica is used in combination, gelation occurs, so that water permeability can be lowered and consolidated even by a single injection. Of course, it is preferable to repeat the injection many times since the improvement effect is further improved.

  The grout used in the present invention may use a curing agent as a component other than microorganisms or nutrient sources of microorganisms. Hardeners include inorganic salts such as bicarbonate, calcium chloride, sodium bisulfate, sodium aluminate, sulfate band, and alum, carbonic acid, carbon dioxide, carbonated water, sulfuric acid, phosphoric acid, hydrochloric acid and other inorganic acids, acetic acid, etc. Organic acids, esters such as diacetin, triacetin and ethylene carbonate, cements such as glyoxal and fine particle cement, slags such as fine particle slag, and alkaline agents such as slaked lime and caustic alkali. Any method may be used as a method of using the composition, but the method is used by infiltrating the injection solution according to the present invention before and after injection.

  In the method of the present invention, it is preferable to inject a calcium salt and a microorganism or a nutrient source of the microorganism into the ground. Microorganisms added from the outside or originally existing in the ground metabolize to release carbon dioxide, which reacts with the carbon dioxide injected into the ground and precipitates as calcium carbonate. The ground is improved by solidifying the precipitated calcium carbonate. The calcium salt that can be used in the method of the present invention is not particularly limited as long as it is a salt that can be dissolved in water near neutral pH, and examples include calcium hydroxide, calcium chloride, calcium nitrate, and calcium carbonate. In particular, use of calcium nitrate is preferable from the viewpoint of water solubility near neutral pH.

  Moreover, when using calcium salt, it is preferable to use a pH buffer together. The pH buffering agent provides a pH environment suitable for generation of carbon dioxide by microorganisms and precipitation of calcium carbonate, and also has an action of preventing a large change in pH in the ground accompanying the precipitation of calcium carbonate. The pH buffering agent is not particularly limited as long as it can maintain the pH in the vicinity of weakly alkaline to weakly alkaline, but in consideration of environmental safety, organic acids such as citric acid and sodium citrate and organic acids A combination of salts, phosphate buffer, Tris buffer and the like are preferable.

  Further, in the method of the present invention, after the injection of grout is completed, a material containing microorganisms that decompose the biodegradable plastic may be further filled in the embedded injection tube. Thereby, even in the construction in the soil that does not contain much microorganisms, it is possible to cause the decomposition of the buried injection pipe that has become unnecessary after the construction. The microorganism-containing material is not particularly limited as long as it does not adversely affect the environment. For example, compost in which microorganisms are present, soil, compost components, dredged soil, dispersion containing microorganisms, bacteria and filaments that decompose organic matter Examples include fermented compost containing a large amount of microorganisms such as fungi. As fermented compost, a soil in which a material containing a large amount of microorganisms such as humus and chicken manure is mixed and microorganisms are sufficiently cultured at high humidity can be used. In addition, by injecting a dispersion containing microorganisms mixed with compost and having fluidity into the soil near the injection ground after injecting the ground consolidation material, not only in the injection pipe but also in the injection pipe Degradation can be further promoted by creating an environment that is easy to biodegrade on the outside. Moreover, it is preferable to send air into the pipe from time to time so that microorganisms can be easily biodegraded.

(Disassembly test)
The degradation of the biodegradable injection tube was tested by an embedding test in combination with each injection material or grout.
An burying test of an injection tube made of a mixture of paper and a lactic acid polymer, an aliphatic polyester polymer, and vinyl chloride was conducted. Using a test apparatus as shown in FIG. 1, around the injection pipe embedded in the simulated ground, a biodegradable plastic-decomposable microorganism, a microorganism nutrient source, an injection material containing a microorganism and a microorganism nutrient source, and a hole wall A protective material was buried around the injection tube, and the state of decomposition of the injection tube was observed. The composition of each injection material and grout is shown below. Silica-based microbial grout, calcium-based microbial grout, and silica-based grout and nutrients were mixed at a ratio of 100 ml of chemical solution to 300 g of sand. The injection tube having a length of 100 mm, an outer diameter of 50 mm, and a tube thickness of 2.5 mm was used. The buried test tube was allowed to stand for about 120 days in a dark place at 58 ° C. and 100% moisture content. The degree of decomposition was evaluated by visual observation and a penetrometer needle penetration test. The results are summarized in Table 3 below.

(Combination of injection material and grout)
[Sand]: River sand for gardening. Water was added so that a thin layer of water was formed on the surface with sterilized ion exchange water.
[Silica-based microorganism grout]: As described in Table 1 below. As the silica compound, commercially available colloidal silica (SiO ₂ concentration of 30.0 wt%, pH around 10 and particle size of 10 to 20 nm) was used.
* 1 Edible yeast was used as a microorganism.
* 2 Glucose was used as a nutrient source.
* 3 Water was added and the total amount of grout was 200 ml.
[Calcium-based microbial grout]: As described in Table 2 below. As a low alkali cement, Geopac grout (manufactured by Reinforced Earth Engineering Co., Ltd.) was used.
* 1 Horticultural humus was used as microbial mixed soil.
* 2 Water was added and the total amount of grout was 200 ml.
[Silica grout and nutrient source]: As shown in Table 3 below. As the silica compound, commercially available colloidal silica (SiO ₂ concentration of 30.0 wt%, pH around 10 and particle size of 10 to 20 nm) was used.
* 1 75% phosphoric acid was used as a pH adjuster.
* 2 Glucose was used as a nutrient source.
* 3 Water was added and the total amount of grout was 200 ml.

Experiments show that biodegradable injection tubes are not embedded in the simulated ground (Comparative Examples 4 and 5) and those embedded in the sand ground (Comparative Examples 1 and 2) are embedded in the grout containing microorganisms In Example 1 , the strength decreased rapidly after 60 days and 120 days. Further, as is clear from the results of Reference Example 2, the strength decreased even with only the nutrient source. As a result of measuring the number of microorganisms by the plate method, both the mold and actinomycetes increased by about ¹⁰⁴ to ⁸ times compared to the ground before injecting the nutrient source, so that the metabolism of the microorganism was activated and promoted the decomposition. It is thought that there is. In Comparative Example 3, which is an injection tube made of vinyl chloride, no strength reduction was observed even after 120 days even though it was embedded in a silica-based microbial grout.

(Flow of gas mixing method)
FIG. 2 is an example of a flow sheet illustrating a method of mixing gas in the actual ground in the present invention. Mainly inserted into the A and B liquid supply pipes 21, a plurality of systems (two systems in FIG. 2) of gas pressure feed lines, that is, the high pressure gas pressure feed pipe 19 and the low pressure gas pressure feed pipe 23, and the ground 9. The injection tube 10 is configured. The A and B liquid storage tanks 4 and 5 may contain a main agent on one side, a gelation modifier and a microbial aqueous solution on one side, a main agent and a gelation regulator on one side, and a microorganism and a nutrient source on the other side. .
The A and B liquid feeding pipelines 21 are piped from the A liquid storage tank 4 and the B liquid storage layer 5 to the injection pipe 10 inserted into the ground 9 and are respectively mixed from the upstream side as shown in FIG. The infusion pump 6 and the flow meter 7 are disposed in the liquid feeding line 21.
The high-pressure gas pressure delivery line 19 is connected to the high-pressure gas container 12 via the connection pipe 14 and is connected to the injection pipe 10. An electromagnetic valve 16, a pressure reducing valve 18, and a gas blowing nozzle 20 are disposed in the pipe line 19. Although not shown, the gas blowing nozzle 20 can be provided in the injection tube 10.
The low-pressure gas pressure delivery line 23 is connected to the high-pressure gas container 11 whose pressure has been reduced via the connection pipe 13 in the same manner as the high-pressure gas pressure delivery line 19, and is connected to the aqueous solution storage tanks 4 and 5 or the aqueous solution delivery line 21. Piping is performed upstream of the mixing tank 8. Similarly to the above, the solenoid valve 15, the pressure reducing valve 17, and the gas blowing nozzle 22 similar to the above are arranged in the pipe line 23, respectively.
According to the apparatus of the present invention having the above-described configuration, the electromagnetic valve 15 and the pressure reducing valve are connected from the low pressure gas container 11 to the upstream side of the solution liquid supply line 21 or in the aqueous solution storage tanks 4 and 5 via the low pressure gas pressure supply line 23. 17 and the gas blowing nozzle 22 are used to inject a gas into the aqueous solution, and then the aqueous solution and the gas are sufficiently mixed in the mixing tank 8 to increase the absorption rate of the gas into the aqueous solution, and the silica compound in which the gas is absorbed by the injection pump 6 The aqueous solution is fed to the injection tube 10 via the liquid feeding conduit 21.
Further, gas is injected into the injection pipe 10 from the high-pressure gas container 12 through the electromagnetic valve 16, the pressure-reducing valve 18, and the gas blowing nozzle 20 through the high-pressure gas pressure feed line 19.
Furthermore, a microbubble generator can be attached to the tips of the gas blowing nozzle 20, the gas blowing nozzle 22, and the aqueous solution feeding conduit 21 to make the gas into microbubbles.

(Construction example of the present invention)
FIG. 3 shows a case where the present invention is implemented as a hole wall protective material or an injection material.
(A) The ground is excavated by the casing 24, and (b) the hole wall protective material 25 is put in the excavation hole. (C) The biodegradable injection pipe 26 is installed, and (d) the casing 24 is pulled out. (E) Injecting material 29 is injected.

(Contamination test for contaminated soil)
The degradation state of the biodegradation injection pipe after in situ purification of the ground contaminated with the organic compound trichlorethylene (TCE) was tested.
1. Earthen tank A simple earthen tank with a diameter of 1 m and a height of 1 m was filled with dredged sand and adjusted so that the porosity was 40% and the water content was 20%. Thereafter, a contaminated soil was prepared by infiltrating a trichlorethylene (TCE) concentration of 0.1 mg / l into the center of a simple soil tank with a diameter of about 30 cm using a biodegradable injection tube.
2. Soil purification method TCE in the ground was decomposed by the following method.
Example 7: A barrier wall was made around the contaminated soil with a mixed solution of the silica compound and the microorganism having the composition shown in Table 1 above, and ferrous sulfide was injected into the contaminated ground.
Comparative Example 6: Ferrous sulfide was injected into the contaminated ground.
Table 5 shows the results of measuring the amount of TCE in the improved ground after soil purification.

  Thereafter, the biodegradable injection tube was left buried in the earth tank, and after 1 year, the excavation appearance was observed and a needle penetration test was performed with a penetrometer. The appearance of Example 7 turned brown and soft when pressed with a finger, and the result of the needle penetration test was 15.3 N / mm, whereas Comparative Example 6 was pale brown and the result of the needle penetration test was 28. It was 6 N / mm.

  From the above results, it was found that the method using the method of the present invention increases the decomposition rate of the biodegradable injection pipe after soil purification and hardly affects excavation work after soil purification.

DESCRIPTION OF SYMBOLS 1 Container 2 Grout 3 Injection pipe 4 A liquid storage tank 5 B liquid storage tank 6 Pump 7 Flowmeter 8 Mixing tank 9 Ground 10 Injection pipe 11 Gas container 12 Gas container 13 Connection pipe 14 Connection pipe 15 Electromagnetic valve 16 Electromagnetic valve 17 Pressure reducing valve 18 Pressure reducing valve 19 High pressure gas pressure delivery line 20 Gas blowout nozzle 21 Aqueous solution feed line 22 Gas blowout nozzle 23 Low pressure gas pressure feed line 24 Casing 25 Hole wall protective material 26 Injection pipe 27 Discharge hole 28 Ground 29 Injection material

Claims (5)

Being embedded in the ground, in method of injecting the soil injection material through buried injection tube to polylactic acid or polylactic acid (/ polybutylene succinate-based) composed of a block copolymer biodegradable plastic key constituents, food Yeast that can be added to food, or yeast that can be added to food and a nutrient source of the yeast, and a grout containing a silica compound is injected into the ground, or yeast that can be added to the food, or the food A ground injection method comprising filling a sealant containing a yeast compound that can be added to the yeast and a nutrient source of the yeast and further containing a silica compound around the injection tube. Being embedded in the ground, in method of injecting the soil injection material through buried injection tube to polylactic acid or polylactic acid (/ polybutylene succinate-based) composed of a block copolymer biodegradable plastic key constituents, food Yeast that can be added to food, or yeast that can be added to food and nutrients of the yeast, and a grout containing calcium salt is injected into the ground, or yeast that can be added to the food, or the food A ground injection method comprising filling a sealant containing a yeast containing a yeast and a nutrient source of the yeast and further containing a calcium salt around the injection tube.   The ground injection method according to any one of claims 1 to 2, wherein the nutrient source is sugar.   The ground injection construction method according to any one of claims 1 to 3, wherein the grout is injected into contaminated soil.   The ground injection method according to any one of claims 1 to 4, wherein a gas is further injected in addition to the grout.