Ground injection method

Abstract

To provide a ground injection method and a ground consolidation material for protecting a concrete structure having an underground space from air strike by missiles and nuclear weapons.SOLUTION: A ground injection method and a ground consolidation material protect a concrete structure which is embedded in the ground and has an underground space from air strike. A ground injection method and a ground consolidation material have good permeability of a consolidation material, are excellent in long-term durability, high strength, earthquake resistance, water cut-off performance, especially, a radiation shielding function, and can also cope with a low carbon type injection method.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a ground injection method used to reinforce underground concrete structures and a ground consolidation material used therein. [Background technology]

[0002] In recent years, from the perspective of national defense, subways, underground shopping malls, tunnels, etc. have been considered as evacuation centers (shelters). However, these underground concrete structures were not built with such a situation in mind, and as they are currently partially deteriorating, reinforcement work is required.

[0003] In particular, when considering attacks by nuclear weapons as well as missiles, underground concrete structures are required to be not only strong but also to shield against radiation. Conventional radiation shielding technologies include those described in Patent Document 1 and Non-Patent Document 1. Additionally, the present applicant has demonstrated the long-term durability and earthquake resistance of technologies described in Patent Documents 2 and 3 and Non-Patent Documents 2 and 3.

[0004] The present invention relates to a ground injection method used to reinforce underground concrete structures, and a ground consolidation material used therefor for strengthening and radiation shielding, which are further developed based on the applicant's injection technology, which has excellent durability, strength, water-stopping properties, and permeability, with the aim of being used for such countermeasures. The present invention provides a ground injection method and ground consolidation material that can strengthen concrete structures that have already deteriorated or are leaking by injecting the ground consolidation material into the outer periphery of existing underground structures that have spaces, thereby protecting the underground space from attacks such as missiles and blocking radiation. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2019 / 031578 [Patent Document 2] Japanese Patent Application Publication No. 2018-193550 [Patent Document 3] Japanese Patent Publication No. 2022-66686 [Patent Document 4] Japanese Patent Application Publication No. 2024-053139 [Patent Document 5] Japanese Patent Application Publication No. 2020-083959 [Non-patent literature]

[0006] [Non-Patent Document 1] Report of the Study Group on the Functions of Evacuation Facilities in Civil Protection, July 2008, Civil Protection Office, Fire and Disaster Management Agency, Ministry of Internal Affairs and Communications [Non-patent document 2] Yurika Tsunoda, Shunsuke Shimada, Tadao Koyama, Takamitsu Sasaki, Ryozo Yonekura, "Demonstration Study on the Permanence and Penetration Consolidation of Ultrafine Composite Silica," 66th Annual Academic Conference of the Japan Society of Civil Engineers, 2011 [Non-patent document 3] Takamitsu Sasaki, Ryozo Yonekura, Shunsuke Shimada, "Field Demonstration Test of the Long-Term Consolidation of Consolidated Ground Using Activated Silica and Ultrafine Composite Silica," 54th Geotechnical Engineering Research Conference, 2019, 0241 Summary of the Invention [Problem to be solved by the invention]

[0007] The present inventors have set the conditions for a ground injection method and a ground consolidation material that are suitable for such purposes as follows. 1) A method of using radiation shielding applied to aboveground structures is already known from Patent Document 1 and Non-Patent Document 1. The present invention aims to realize the strengthening and protection of underground structures by an injection method. 2) It must have excellent long-term durability (because it is not known when an air raid will occur), high strength (it must be able to withstand the impact of an air raid), and earthquake resistance (an earthquake may occur before an air raid). 3) Excellent permeability (requiring permeability and solidification that can cover the injection limit of high-strength suspension grout) and water-stopping properties (requiring the ability to repair deterioration of existing concrete structures. Also, water-stopping properties are required to prevent groundwater containing radiation from leaking into underground spaces). 4) It is an injection material with radiation shielding properties (it contains particles with radiation shielding properties, penetrates into the ground and solidifies, and it is desirable that the solidified material is a water-containing solidified material). 5) It is desirable to use a low-carbon injection method. (From the perspective of preventing global warming, it is desirable to use an injection material that can reduce CO2 emissions.)

[0008] Therefore, the object of the present invention is to provide a ground injection method and ground consolidation material for protecting concrete structures with underground spaces from air attacks by missiles and nuclear weapons, which have good permeability, long-term durability, high strength, earthquake resistance, water-stopping properties, and especially excellent radiation shielding properties, and are also compatible with low-carbon injection methods. [Means for solving the problem]

[0009] In the present invention, the ground injection method for solving the above-mentioned problem 1) is carried out as shown in Figures 1(a) to 1(c). In order to solve the above-mentioned problems 2) to 5) in this injection method, it is a further development based on the technology of the present applicant. A. Regarding the above issue 2), development will be based on prior patent documents 2, 3 and non-patent documents 2, 3, in which long-term durability and earthquake resistance have been demonstrated in indoor tests, large-scale field tests, and actual earthquakes. B. Regarding the above problem 3), we will develop high strength and permeability based on Patent Documents 3 and 4. C. Regarding the above problem 4), development will be based on the above A and B and Patent Documents 1 and 5.

[0010] Based on the above findings, the present inventors have (1) In order to strengthen underground structures with underground spaces so that they can withstand the impact of air raids, we developed a technology based on the technologies of Patent Documents 3 and 4 that can be expected to have strength, permeability, and watertightness, and (2) In order to protect underground structures with underground spaces from radiation from nuclear missiles, etc., we have developed a technology that applies a solidifying agent that forms a hydrous gel based on the above (1) and also on Non-Patent Document 1 and Patent Document 1.

[0011] That is, the ground injection method of the present invention is a ground injection method for protecting a concrete structure buried underground and having an underground space from air raids, The method is characterized in that the concrete structure is reinforced by injecting the following ground consolidation material (A) and / or (B) into the periphery of the concrete structure from a plurality of injection pipes inserted into the ground. (A) A suspension grout whose main component is silica particles, and whose active ingredients are one or more of a hardener, an alkali agent, and solution-type silica. (B) Non-alkaline silica grout.

[0012] The ground grouting method of the present invention is suitable for use in protecting the concrete structure from air attacks by nuclear missiles by using a ground consolidation material containing radiation-shielding particles.

[0013] In the ground grouting method of the present invention, it is preferable that the solution-type silica contains silica colloid and / or water glass, and the bleeding liquid of the ground consolidation agent gels.

[0014] In the ground grouting method of the present invention, the silica particles preferably contain one or more of calcined silica, pozzolanic natural silica, and hardenable silica particles as active ingredients. The calcined silica is preferably made of one or more of slag, fly ash, cement, sewage incineration ash, plant incineration ash, and calcined clay, and the pozzolanic natural silica is preferably made of one or more of loam, shirasu, volcanic ash, niwado, and sanwado.

[0015] In the ground grouting method of the present invention, the alkaline agent preferably comprises one or more of the following (1) to (3): (1) An alkaline agent containing gypsum and / or MgO as active ingredients. (2) An alkaline agent containing one or more of Ca salts, Ma salts, Al salts, carbonates, and bicarbonates as active ingredients. (3) Alkaline agents containing one or more of lime, cement, caustic alkali, water glass, and silica colloid as active ingredients.

[0016] In the ground grouting method of the present invention, the silica particles have a Blaine value of 4000 to 20000 cm 2 It is preferable to use silica particles having a density of 1 / g and to set the blending amount of the silica particles in the ground consolidation material to 50 to 150 L / 400 L. Furthermore, in the ground grouting method of the present invention, it is preferable that the silica particles are slag, and the blending amount of the slag in the ground consolidation material is 10 to 25 mass % when no cement is used, and 10 to 30 mass % when cement is used.

[0017] In the ground grouting method of the present invention, it is preferable that the molar ratio of the water glass is 1.0 to 5.0, and the amount of the water glass mixed in the ground consolidation material is 10 to 150 L / 400 L.

[0018] In the ground injection method of the present invention, the ground consolidation material is a suspension containing the silica particles as a main component and the solution-type silica as an active ingredient, and when the ground consolidation material is injected into the ground from the multiple injection pipes, The bleeding liquid of the ground consolidation material gels, and the homogel has a strength to stand on its own, and the sand gel solidified by the penetration of the bleeding liquid has a strength to stand on its own, The bleeding liquid can penetrate into parts of the ground that the suspension could not penetrate, thereby expanding the solidification range, or can be made to integrate with the parts of the ground that the suspension has penetrated into to form a solidified body. Here, in the above, the bleeding liquid gelling and the resulting homogel being self-supporting means that the silica concentration of the bleeding liquid is 0.5 w / v% or more, and the homogel is self-supporting without collapsing even when tilted diagonally within the mold. The sand gel being self-supporting means that the silica concentration of the bleeding liquid is 0.5 w / v% or more, the sand gel is prepared by a mixing method using No. 6 silica sand and the bleeding liquid so as to have a relative density of 60% and has a diameter of 5 cm and a height of 10 cm, is self-supporting, and the strength in a uniaxial compression test measured using the sand gel is 2.0 kN / m 2 This means that it is more than or equal to this.

[0019] In the ground grouting method of the present invention, a formulation for the ground consolidation agent can be set to provide a lightweight, low-alkali, and low-carbon type ground improvement agent.

[0020] In the ground grouting method of the present invention, the ground consolidation material preferably contains one or more of microbubbles, air, a dispersant, and a thickener as active ingredients.

[0021] In the ground grouting method of the present invention, the hardener is preferably a polyvalent metal compound, and is preferably one or more of hydroxides, oxides, or salts of Ca, Mg, or Al, and / or gypsum.

[0022] In the ground injection method of the present invention, the improvement effect achieved by injecting the ground consolidation material can be confirmed by non-destructive testing, and the non-destructive testing can be performed using elastic wave velocity logging, acoustic tomography, or surface wave exploration.

[0023] The ground consolidation material of the present invention is used in the above-mentioned ground injection method and is a ground consolidation material for protecting concrete structures buried in the ground and having underground spaces from air attacks by nuclear missiles, and is characterized in that the ground consolidation material contains radiation-shielding particles.

[0024] The ground consolidation material of the present invention is composed of (B) non-alkaline silica grout having a pH of 1 to 10, and contains as active ingredients one or more of silica colloid and water glass, and one or more of acids and salts as reactants. When the (B) non-alkaline silica grout is composed of silica colloid, water glass, and acid, it is preferable that the ratio of the silica concentration resulting from silica colloid to the silica concentration resulting from water glass is 100:0 to 0:100, the silica concentration is 0.4 to 40 wt%, the molar ratio of silica is 2.0 to 100, and the gelation time is from instantaneous setting to 10,000 minutes. The non-alkali silica (Patent Document 2) and clay grout (Patent Document 5) can be injected further around the permeated and solidified area of ​​the suspension grout (Fig. 13) to improve water-stopping properties and radiation shielding effects by forming a hydrogel. [Effects of the Invention]

[0025] According to the present invention, there is provided a ground injection method and a ground consolidation material for protecting concrete structures with underground spaces from air attacks by missiles and nuclear weapons, which have good permeability, long-term durability, high strength, earthquake resistance, water-stopping properties, and especially excellent radiation shielding properties, and are also compatible with low-carbon injection methods. [Brief explanation of the drawings]

[0026] [Figure 1] (a) to (c) are explanatory diagrams relating to the ground injection method of the present invention, where (a) shows an example of reinforcement injection into the surrounding area of ​​a tunnel, (b) shows an example of repairing concrete from inside an underground structure in use and reinforcing injection into the surrounding ground, and (c) shows an example of strengthening an underground structure. [Figure 2] FIG. 10 is a photograph showing the bleeding state of the sample of Example 36. [Figure 3] FIG. 1 is a photograph showing the bleeding state of the sample of Comparative Example 1. [Figure 4] FIG. 10 is a photograph showing the state of the sample of Example 36 several days after penetration. [Figure 5]FIG. 1 is a photograph showing the state of the sample of Comparative Example 1 several days after penetration. [Figure 6] 1 is a graph showing the results of a long-distance penetration test for Example 36 and Comparative Example 1. [Figure 7] 7 is a graph showing an enlarged portion of the permeation distance of 90 cm to 120 cm in FIG. 6. [Figure 8] This is a photograph showing the state in which the bleeding liquid has gelled and the gel does not collapse (stands on its own) even when tilted. [Figure 9] This is a graph showing particle size accumulation curves for various on-site sands that have been treated with liquefaction countermeasures using solution-type grout. [Figure 10] FIG. 10 is a photograph showing the strength measurement status of a test specimen using a bleeding liquid on the 7th day. [Figure 11] FIG. 10 is a photograph showing the state of the test specimen after strength measurement of the test specimen using the bleeding liquid. [Figure 12] 1 is a graph showing the physical properties of the sand used. [Figure 13(a)] FIG. 2 is an explanatory diagram showing the form of infiltration and solidification in the ground injection method of the present invention. [Figure 13(b)] FIG. 10 is an explanatory diagram showing another form of permeation consolidation in the ground injection method of the present invention. [Figure 13(c)] FIG. 10 is an explanatory diagram showing yet another form of permeation consolidation in the ground injection method of the present invention. [Figure 13(d)] FIG. 10 is an explanatory diagram showing yet another form of permeation consolidation in the ground injection method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The ground injection method of the present invention is a ground injection method for protecting a concrete structure buried underground and having an underground space from air raids, and is characterized in that the concrete structure is reinforced by injecting the following ground consolidation material (A) and / or (B) from multiple injection pipes inserted into the ground into the periphery of the concrete structure. (A) A suspension grout whose main component is silica particles, and whose active ingredients are one or more of a hardener, an alkali agent, and solution-type silica. (B) Non-alkaline silica grout.

[0028] Specific means for solving the problems in the present invention will be described below. 1) The present applicant has already developed a high-strength permanent grout (Patent Documents 3 to 5) that uses silica particles such as slag and fly ash as a permanent grout as a low-carbon injection material and injection method.

[0029] 2) The applicant has already developed a non-alkali silica grout with excellent permeability and durability (Patent Document 2). This is a low-carbon grout, and its long-term durability and earthquake resistance have been demonstrated (Patent Documents 2 and 3).

[0030] 3) Based on Patent Document 3, the inventors have realized ground improvement by simultaneous combined injection of suspension and solution, which integrates the entire target ground with high strength, excellent penetration and solidification properties, and excellent water-stopping properties, because the ultrafine particle composite silica consisting of silica particles and silica solution covers the injection limit of silica particles with the gelling function of the bleeding liquid, and the bleeding liquid penetrates and solidifies even in areas where silica particles cannot penetrate (Figure 13).

[0031] 4) Radiation shielding is achieved by covering the underground structure with a high-strength solidified material as described in 3) above, and then covering the surrounding area with water-stopping hydrous silica gel or clay gel. Furthermore, by adding a material containing fine particles with radiation-shielding properties to the high-strength grout, it is possible to create a radiation-shielding grout that is high-strength, has excellent water-stopping properties, and has radiation-shielding properties. By injecting this into the ground around a concrete structure, it is possible to strengthen the underground structure. Particles with radiation shielding properties are already known in Patent Document 1. Types of radiation and types of shielding materials are also known in Non-Patent Document 1. However, these technologies all relate to the radiation shielding effect of above-ground structures. The present invention relates to a technology that enables the strengthening and radiation shielding of underground structures by an injection method.

[0032] 5) The radiation permeability depends on the type of radiation and the type and thickness of the shielding material contained in the grout. The radiation transmission coefficient for the wall thickness of an underground concrete structure (underground shelter) is described in Non-Patent Document 1. It states that the transmission coefficient for an underground shelter approximately 80 cm thick is 0.0002, and for an underground shelter made of concrete blocks with a wall thickness of approximately 61 cm, the transmission coefficient is 0.0001 to 0.002. Furthermore, Figure 15 of Non-Patent Document 1 describes the types of radiation and shielding materials, and the types and properties of radiation. Furthermore, Patent Document 1 describes carbon nanohorns, nanographite, tungsten, and graphene as shielding particles. Furthermore, because water has a shielding effect, hydrogels containing these are effective. Clay grout is described in Patent Document 5, and hydrogels containing clay are effective as radiation shielding materials. Therefore, these factors should be taken into consideration when determining the thickness and strength of the consolidation produced by the suspension grout formed on the periphery of the concrete structure. However, in the construction of the present invention, the construction is carried out as shown in the example of Figures 1(a) to (c), so the distance between injection holes that can connect the penetration range from the injection hole is set to 1 m, the consolidation thickness is set to 1 m or more, and even in ground containing fine-grained soil, this injection material, which has high-strength penetration consolidation and water-stopping properties as described below, is injected.

[0033] 6) Regarding the above, radiation shielding, types of radiation, and the function of the shielding material are described in Patent Document 1. Furthermore, a method for producing particles with radiation shielding function is described in Patent Document 2. The present invention provides a ground grouting method and ground consolidation material that solve the above-mentioned problems by injecting a high-strength grouting material with excellent permeability and durability, or by injecting the above-mentioned grouting material with high-strength permeability and water-stopping properties and further containing fine particles with radiation-shielding function into the ground, thereby strengthening underground structures, preventing water leakage, and shielding radiation. Therefore, below, we will describe a method for strengthening underground structures using a ground grouting method that can achieve long-term durability, permeability, solidification, high strength, and water-stopping properties.

[0034] From the above, the technology of the present invention is as follows: 1. Strengthening underground structures by injecting high-strength, permeable grouting materials; 2. The gelation of the bleeding liquid of the suspension containing silica solution solidifies fine-grained soil that silica particles cannot penetrate, and the penetration and solidification of the bleeding liquid forms a larger solidified body than the solidified body of silica particles, making it possible to reinforce underground structures by simultaneous composite injection of suspension and solution (Figure 13), which has strength, permeability, water-stopping effect, and radiation shielding effect. 3. A radiation shielding injection method using the above-mentioned injection material containing fine particles with radiation shielding effect. The most important technology, point 2 above, will be mainly explained below.

[0035] In conventional injection materials, the main component of suspension grout is cement, which has a high specific gravity of 3.17, but a specific surface area of ​​3,220 cm 2 / g, and the cement particles are heavy. In addition, penetration between soil particles in fine-grained soil is difficult, resulting in a short penetration distance, making it difficult to form large solidified bodies.

[0036] With high-pressure jetting methods that primarily use cement, the improved soil is in an unsolidified state immediately after construction because sufficient hydration reactions have not yet occurred. Therefore, when construction is carried out near a structure, the bearing capacity may be reduced, hindering the function of the structure. Furthermore, with conventional high-pressure jetting methods that rely on the energy of the high-pressure jet fluid, the cutting area is limited by the distance of the jet fluid, which restricts the size of the improved soil using cement solidification materials.

[0037] Furthermore, in the high-pressure jetting method, the soil is removed and replaced with cement to form a solidified body, so disposal of the removed mud has become a major environmental problem.Furthermore, when improving soft ground, there is a problem that the improved cement-solidified body is prone to subsidence because soft ground has little bearing capacity, and this can easily lead to large displacement of structures.

[0038] As a result of continuing research into the gelation of bleeding liquids, the inventors discovered that suspensions containing solution-type silica gel regardless of whether the bleeding rate is 50% or less or 50% or more (Figures 2, 4, 8, and Table 8). They also found that the gelation time and strength of bleeding can be adjusted by adding a curing agent. They also found the relationship between the silica concentration sufficient for the homogel and sand gel to self-sustain regarding the gelation of the bleeding liquid (Table 9, Figures 2, 4, 6-8, 10, and 11).

[0039] Figures 13(a) to (d) show the form of permeation and consolidation by the ground grouting method of the present invention. Figure 13 shows that by injecting the silica suspension, the suspended particles permeate between the soil particles, and the bleeding liquid permeates and solidifies, creating an integrated permeation and consolidation area. Figure 13 corresponds to Figures 6 and 7. Therefore, the silica particles in the suspension, or even the bleeding liquid, can penetrate and solidify into the ground from multiple injection holes, making it possible to improve the ground as a whole (Figures 13(c) and (d)). Furthermore, the present invention has substantially expanded the injectable limit of suspension grout (Fig. 12) to include solution-type grout (Fig. 9), and has developed into a ground improvement method based on a new technological concept of simultaneous combined injection of suspension and solution.

[0040] Furthermore, the present invention relates to a ground injection method for improving the soft ground or liquefied ground around the above-mentioned underground structures with high strength and light weight, in which silica particles, slag-based or other solidifying materials are infiltrated into the surrounding area to form large solidified bodies, enabling low-carbon ground improvement. By using a suspension-type solidifying material mainly composed of calcined silica such as slag or fly ash, or silica particles with natural pozzolanic action, a non-cement-based solidifying material or a solidifying material with reduced cement content can be used, reducing CO2 emissions. 2 Furthermore, by including solution-type silica in the suspension-type silica particles, the bleeding liquid of the suspension becomes a penetrating gel, expanding the range of penetration and solidification, achieving high-strength solidification effects and water-stopping effects, as well as enabling ground improvement that can repair deteriorated underground concrete structures.

[0041] For this reason, the present invention uses artificial calcined silica such as silica powder, slag, or fly ash as the main component, or uses natural silica particles with pozzolanic action as the main component, or forms a solidified body using a small amount of cement, thereby providing the advantage of reducing the weight of the improved body in the entire improved area and eliminating settlement caused by the improved body. This is because cement has a specific gravity of 3.15, while slag has a specific gravity of 2.9, fly ash has a specific gravity of 2.8, and volcanic ash generally has a specific gravity of 0.9 to 2.5, which is almost the same as ordinary soil.

[0042] Table 1 below shows an example of a consolidated strength test of a mixture with a consolidating agent when the ground is sandy or clayey soil. Tables 1 through 7 show examples of the consolidation strength of consolidation materials or their strength when mixed with in-situ soil. Table 8 shows the uniaxial compressive strength of sand gels produced by gelling bleeding liquid. In this invention, a lightweight suspension based on small, highly fluid silica particles is selected depending on the ground conditions. This allows penetration into the surrounding ground. If the suspension contains solution-type silica, the bleeding liquid gels and solidifies. This extends the consolidation range to areas that cannot be reached by suspension alone, achieving both a watertight effect and continuous solidification between the consolidations (Figures 2, 4, 6 through 11). Figure 9 shows the particle size distribution curves for solution-type grouts that achieve a permeation consolidation effect. The suspension-type consolidation material, based on the silica particles containing solution-type silica, can penetrate and consolidate ground with the particle size distribution shown in Figure 9. This enables a new ground grouting method based on the concept of "simultaneous combined suspension / solution injection," which combines the advantages of both suspension and solution injection methods. Figure 12 shows the particle size distribution of the permeable limit of the suspension grout without silica solution.

[0043] The ground consolidation material used in the present invention will be described below. The ground consolidation material of the present invention is used in the ground injection method of the present invention, and is used to protect concrete structures buried underground and having underground spaces from air attacks such as nuclear missiles.

[0044] As described above, the ground consolidation material of the present invention preferably comprises (A) a suspension-type grout containing silica particles as the main ingredient and one or more of a hardener, an alkali agent, and solution-type silica as active ingredients, and / or (B) a non-alkali silica grout, and contains radiation-shielding particles.

[0045] (A) Suspension grouts are primarily composed of silica particles, with one or more of a hardener, alkali, and solution-type silica as active ingredients. Suspensions primarily composed of silica particles are prepared by suspending calcined silica, such as slag or fly ash, in water, and mixing this with a hardener, such as water glass and / or an alkali. The silica particles preferably contain one or more of the following active ingredients: calcined silica, natural silica with pozzolanic properties, and hardenable silica particles (cement).

[0046] Among these, pyrogenic silica includes slag and fly ash, as well as cement, paper sludge, sludge incineration ash, sewage incineration ash, plant incineration ash, and calcined clay, as well as plant incineration ash rich in silica. Any one or more of these can be used. Furthermore, natural silica with pozzolanic properties includes natural calcined soils such as loam, volcanic ash, and ferrous clay. Any one or more of these can be used. These pyrogenic silicas are silica particles with pozzolanic properties, containing soluble silica. They form a crystalline structure similar to that of cement through hydration reactions with alkalis such as slaked lime, gypsum, magnesium hydroxide, water glass, silica colloid, caustic alkali, carbonate, bicarbonate, aluminum salt, calcium salt, and magnesium salt, thereby solidifying firmly. Furthermore, the use of aggregates such as soil and clay as thickeners or bulking agents in these compounds enables economical ground improvement. Furthermore, the on-site soil can be slurried with the above-mentioned hardener.

[0047] The above silica particles have a Blaine value of 4000 to 20000 cm 2 / g enables penetration between soil particles. Furthermore, high strength can be achieved by using artificial or natural calcined silica as the silica particles and setting the silica particle content in the ground consolidation agent to 50 to 150 L per 400 L. The amount of calcined silica, such as slag, in the consolidation agent of the present invention is determined depending on the desired strength of the hardened product, but is preferably 10 to 25 mass% when cement is not used, and 10 to 30 mass% when cement is used. In particular, when slag is used as the silica particles in the consolidation agent, it is preferable to set the slag content in the ground consolidation agent to 10 to 25 mass% when cement is not used, and 10 to 30 mass% when cement is used, since this will result in high strength.

[0048] The hardener used in the binder of the present invention may be a polyvalent metal compound, such as one or more of hydroxides, oxides, or salts of Ca, Mg, or Al, and / or gypsum. Specifically, it may be a calcium molten material such as cement, slaked lime, or gypsum, or an alkali agent. Slaked lime is particularly preferred for shortening gelation time and improving early strength. The binder may also be used in combination with fillers such as slag, bentonite, calcium carbonate, clay, and silica powder such as earth and sand. Plastic grout may also be made using fillers such as fly ash, polymers, cement, and plasticizers such as aluminum salts, thickeners, and clay.

[0049] The alkaline agent used in the binder of the present invention may be one or more of the following (1) to (3). (1) An alkaline agent containing gypsum and / or MgO as active ingredients. (2) An alkaline agent containing one or more of Ca salts, Ma salts, Al salts, carbonates, and bicarbonates as active ingredients. (3) Alkaline agents containing one or more of lime, cement, caustic alkali, water glass, and silica colloid as active ingredients.

[0050] The solution-type silica used in the consolidation agent of the present invention preferably contains silica colloid and / or water glass, which causes the bleeding liquid of the consolidation agent to gel. In this case, it is preferable that the molar ratio of water glass is 1.0 to 5.0, and the amount of water glass in the ground consolidation agent is 10 to 150 L / 400 L.

[0051] As the radiation-shielding particles used in the binder of the present invention, conventionally known particles such as clay, carbon nanohorn, nanographite, tungsten, graphene, etc. can be used.

[0052] In the present invention, the slag used is finely pulverized blast furnace slag. In order to enhance reactivity, the finer the particle size, the better. For example, slag having a specific surface area (Blaine value) of 4000 cm 2 / g or more, preferably 6000 cm 2 / g~20000cm 2 / g and an average particle size of 10 μm or less is suitable.

[0053] In the present invention, the water glass preferably has a high alkali concentration due to its reactivity with slag, and particularly one with a SiO2 / Na2O molar ratio of 2.5 or less is preferred. A low molar ratio results in a high-strength solidified body and a long gelation time. Examples of water glass that can be used include mixtures of anhydrous sodium orthosilicate and sodium hydroxide, crystalline sodium silicate containing sodium metasilicate, mixtures containing a portion of crystalline sodium silicate, sodium silicate glass (cullet), hydrated glass, dehydrated sodium silicate, semisolid sodium silicate, viscous sodium silicate, and commercially available dilute solutions of sodium silicate. Water glass with a molar ratio of 2.0 to 5.5, silica solutions with a higher molar ratio obtained by mixing silica colloid with water glass, and other water glass solutions with different viscosities, molar ratios, and silica concentrations may also be used, or the water glass may be used as a powder. The alkali content of water glass stimulates the hydraulic properties of slag. Water glass with a low molar ratio may be a mixture of water glass and caustic alkali. However, when used in combination with calcium molten materials such as slaked lime or cement, water glass with a high SiO2 / Na2O molar ratio, such as water glass No. 3 and No. 4, can be used. As the silica solution, silica colloid can be used in addition to water glass, and a mixture of silica colloid, calcined silica such as slag, and cement can also be used.

[0054] The salts used in the present invention may be aluminum compounds such as aluminum sulfate and polyaluminum chloride, or products obtained by reacting these with caustic alkali. Furthermore, the molar ratio of Na2O / Al2O3 is not particularly limited, but the Na2O concentration in the binder is preferably 5% by mass or more due to its reactivity with slag. Caustic alkali is effective in stimulating the hydraulic properties of slag, and the aluminum reacts with water glass and the silica in the slag to form aluminum silicate and calcium aluminosilicate.

[0055] The amounts of water glass and aluminum compound in the binder are such that the hardening time of the binder is several hours, usually within one hour, and preferably within 30 minutes, and although this varies depending on the molar ratio of Na2O, Al2O3, and SiO2, an amount that makes the Na2O content in the binder 2 mass% or more is preferred. However, when consolidating a wide area, amounts that will result in hardening time of several hours are required.

[0056] Furthermore, the consolidating agent of the present invention can be made lighter by adding a foaming agent or foaming agent to improve its fluidity, and by adding clay, bentonite, or polymeric thickeners such as polyvinyl alcohol, carboxymethyl cellulose (CMC), or methyl cellulose, it can be made to suppress dispersibility in water, reduce precipitation, and improve workability. It can also function as a water-retaining material or a binder for silica particles such as slag, which forms a pseudo-gel-like fluid that maintains fluidity but is difficult to disperse. This reduces diffusion and dilution in the ground and promotes the expansion of the consolidation body.

[0057] In the present invention, microbubbles or microbubbles and air can be mixed into the above-mentioned suspensions of slag, fly ash, etc., or suspensions of cement, etc., and then injected into the cutting area. This allows the microbubbles or microbubbles and air to cover the suspended particles, creating a wide-area solidified body. It also reduces the weight and strength of the solidified body by increasing the amount of gas in the solidified body. It has also been found that the presence of air bubbles in the solidified body improves the liquefaction prevention effect even when the amount of suspended particles in the solidified body is small and the strength is low. Furthermore, in addition to microbubbles and air, the consolidating agent of the present invention can also contain dispersants and thickeners, and one or more of these can be used as active ingredients.

[0058] The ground consolidation material of the present invention can also be embodied as follows. The ground consolidation material of the present invention is composed of (B) non-alkaline silica grout having a pH of 1 to 10, and contains one or more of silica colloid and water glass, and one or more of acid and salt as a reactant as active ingredients. When (B) non-alkaline silica grout is composed of silica colloid, water glass, and acid, the ratio of the silica concentration due to silica colloid to the silica concentration due to water glass can be 100:0 to 0:100, the silica concentration can be 0.4 to 40 wt%, the molar ratio of silica can be 2.0 to 100, and the gelation time can be from instantaneous setting to 10,000 minutes.

[0059] In the present invention, a formulation for a ground consolidation agent that is lightweight, low in alkali, and low in carbon can be set to provide ground improvement.

[0060] In the present invention, the binder may be directly mixed and sent to the injection rod as a single liquid, or the above-mentioned suspension (liquid A) and water glass and / or alkaline agent (liquid B) may be pumped, mixed, and then injected. In this case, liquid A and liquid B are preferably mixed at a ratio of approximately 1:1 (by volume), but are usually mixed at any ratio within the range of 10:1 to 1:10.

[0061] In the present invention, the improvement effect of the injection of the ground consolidation material can be confirmed by non-destructive testing, which can be performed using elastic wave velocity logging, acoustic tomography, or surface wave exploration.

[0062] (test) Clayey soil and sandy soil were used, and these were mixed and consolidated with the above-mentioned consolidating agent of the present invention. The test results of the example in which the strength of the consolidated body was measured are shown in Table 1.

[0063] As can be seen from the following, cement-free consolidation materials that are primarily made of calcined silica or natural silica with pozzolanic properties, or that use reduced amounts of cement, have a lower specific gravity than cement-based consolidation materials, and therefore can be used to consolidate the ground using a material that has almost the same specific gravity as the original ground, or even a lighter material, thereby achieving the effect of lightweight consolidation.

[0064] [Materials used] Slag: specific gravity 2.9, Blaine value 8000 cm 2 / g, a silica-based non-hardening powder. Fly ash (FA): Coal ash discharged from thermal power plants. It is a silica-based non-hardening powder. Its specific gravity is 1.9-2.3g / cm. 3 The particle size distribution is 0.1 mm or less, with more than 90%. Cement: Ordinary Portland cement: PC, specific gravity 3.15, hardening agent. Aluminum sulfate: Aluminum sulfate, Al2O3=17.2%, gelling agent, specific gravity 1.32. Slaked lime: industrial calcium hydroxide, gelling accelerator and hardener. Gypsum or gypsum hemihydrate: hardening material, specific gravity 2.6. Bentonite: Water-retaining and thickening agent, specific gravity 2.6. Magnesium oxide (gelling agent): specific gravity 3.65. Calcium chloride (gelling agent): specific gravity 1.85. Baking soda: specific gravity 2.2. Dispersant: Specific gravity 1.04. Sulfuric acid: specific gravity 1.67, 75w / w%. No. 5 water glass: specific gravity 1.32, silica concentration 25.5%, Na2O 7.03, molar ratio 3.75. No. 1 water glass: specific gravity 1.35, silica concentration 21.59%, Na2O 10.80%, molar ratio 2.06. No. 3 water glass: specific gravity 1.41, silica concentration 29.16%, Na2O 9.36, molar ratio 3.22. Polyaluminum chloride and foam materials can also be used.

[0065] [Test method and test results] The specimens for the unconfined compression strength tests in Tables 1 to 7 were prepared in accordance with the Japanese Industrial Standard (draft) (JIS A 1216:2020) for unconfined compression testing of soil, using cylindrical specimens with a height of 100 mm and a diameter of 50 mm. The results of measuring the strength on the 1st, 7th, and 28th days, or on the 28th day, are shown, respectively.

[0066] [Table 1]

[0067] [Table 2]

[0068] [Table 3]

[0069] [Table 4]

[0070] [Table 5]

[0071] [Table 6]

[0072] [Table 7]

[0073] [Table 8]

[0074] The consolidating agent of the present invention can penetrate and consolidate sandy ground. In particular, when the consolidating agent contains solution-type silica, it penetrates and solidifies fine-grained soil, connecting the consolidations and providing a water-stopping effect.

[0075] Below, we will explain test examples (Figs. 2 to 11) that demonstrate the effect of gelling the bleeding liquid in the silica suspension containing the silica solution. Fig. 8 shows the state in which Fig. 2 is tilted. Table 8, Figs. 7, 10, and 11 show the state of strength tests of sand specimens solidified with the bleeding liquid.

[0076] (Permeability test) (Test equipment and test method) A one-dimensional infiltration test was carried out on No. 6 silica sand using a one-dimensional infiltration apparatus (length 2m), and the infiltration length and strength distribution were investigated.

[0077] Test conditions: acrylic mold h=2m, mixed liquid 3L After the sample was saturated with water, the suspension was poured into the bottom until no more liquid was discharged.

[0078] The specimens were prepared in accordance with the Japanese Industrial Standard (draft) (JIS A 1216:2020) for the unconfined compression test of soil, and cylindrical specimens with a height of 100 mm and a diameter of 50 mm were used for the unconfined compression test.

[0079] The tests were carried out using the formulations of Example 36 and Comparative Example 1 (Figs. 4 to 7, 10, and 11).

[0080] The solid lines in Figures 6 and 7 show the results for the formulation of Example 36. Strength measurements were possible even at a penetration distance of 120 cm. Although there was no discoloration of the sand gel after 90 cm, the strength measurements were possible because the bleeding liquid solidified after 90 cm. The portion after 90 cm is believed to contain 0.5% or more silica.

[0081] The dotted lines in Figures 6 and 7 show the results obtained with the formulation of Comparative Example 1. The strength could be measured up to 90 cm, but there was no discoloration after 90 cm, making it impossible to measure the strength, and it was found that the bleeding liquid had not gelled.

[0082] In the penetration test shown in Figure 5, the areas where there was no discoloration of the sand are thought to be areas where slag had not penetrated. The bleeding fluid was not self-supporting, and the areas where the bleeding fluid had penetrated were also not self-supporting and had not solidified. In contrast, in Figure 6, the bleeding fluid had gelled, and the bleeding fluid was self-supporting, and the sand gel did not discolor, but was self-supporting and exhibited strength.

[0083] From the above, under conditions where the soil particle size density and particle size distribution of suspended particles prevent penetration between soil particles, only the bleeding liquid will penetrate (Figures 9 and 12).

[0084] Figures 6 and 7 show that even if the penetration distance of the suspended particles in the suspension is 90 cm, the bleeding liquid penetrates up to 120 cm, and the bleeding liquid is strong enough to stand on its own, and the sand gel is strong enough to stand on its own. In this case, it can be predicted that the silica concentration should be 0.5 to 2% or more (Table 9). Therefore, even if the injection hole spacing is long, the homogel of the bleeding liquid will connect the solidified bodies penetrated by the suspended particles, which will obtain high strength.

[0085] In this way, an integrated solidified body can be formed even under ground conditions where suspended particles cannot penetrate, and even if the injection hole spacing is wide, the solidified bodies between them can be connected by the gelled product of the bleeding liquid, which can stand on its own, thereby forming an integrated solidified ground.

[0086] Suspension grout can achieve higher strength than solution grout, but its large particle size makes it less permeable to fine-grained soil. However, by including solution silica, a solidification effect can be achieved even in ground that cannot be penetrated by suspended particles, making it possible to achieve integrated ground improvement and watertightness (Figure 13).

[0087] As mentioned above, the inventors have also focused on the gelation of the bleeding liquid of the suspension grout, and have studied the gelation of the bleeding liquid, the self-sustaining ability of the homogel of the bleeding liquid, and the self-sustaining ability and strength of the sand gel of the bleeding liquid, and by using these as conditions, they have improved the penetration and consolidation ability of suspension grout for fine-grained soil or ground containing fine-grained soil, which was previously thought to be inapplicable, and have completed the present invention. Furthermore, according to the present invention, improvement effects can be obtained, enabling the excavated surface to stand up and become waterproof, even in excavated ground.

[0088] In particular, when a suspension containing a silica solution is used in the present invention, the following effects are achieved by gelling the bleeding liquid, which cannot be achieved by conventional high-pressure spraying methods. (1) Permeation consolidation of fine-grained soil where permeation consolidation of suspended particles was previously impossible. (2) Self-supporting effect and water-tightness of the cutting surface. (3) Expansion of the improvement area through permeation and solidification. (4) Ground improvement in which adjacent solidified bodies are connected and integrated. (5) Reduction of construction work by increasing the hole spacing of the injection pipe. (6) The bleeding liquid has a short-term solidification effect, which improves resistance to earth pressure from adjacent structures and the back of retaining walls, improving construction safety; the penetration injection ensures safety for buried objects; the strengthening of the ground surrounding underground structures with spaces, waterproofing, and repair of deterioration.

[0089] An example is shown below. (Strength test) (Preparation of sand gel specimen) Using No. 6 silica sand (Figure 12) and a bleeding liquid, specimens measuring 5 cm in diameter and 10 cm in height were prepared using a mixing method to achieve a relative density of 60%, and the unconfined compressive strength was measured after 28 days. The bleeding rate was higher when the amount of water glass was greater, and increased when the amount of slag was reduced. In sand gels using bleeding liquid, greater amounts of water glass and slag were used, resulting in greater strength. In addition, in cases where gypsum was used in combination, the bleeding rate decreased and strength increased when gypsum was added.

[0090] The gelation and self-sustaining properties of the bleeding fluid, as well as the strength and self-sustaining properties of the sand solidified by the bleeding fluid (sand gel), depend on the amount of slag and water glass in the suspension, the ratio of the silica concentration (SiO2) of the water glass to the CaO content of the slag (CaO / SiO2), the gel time, and the particle size and density of the sand solidified by the bleeding fluid. Therefore, tests were conducted to determine the minimum gelation and self-sustaining properties of the bleeding fluid, as conditions that comprehensively affect these factors (Table 9, Figures 6 and 7). As a result, it was found that, provided that the bleeding fluid gelation and self-sustaining properties and the self-sustaining properties of the sand gel infiltrated with the bleeding fluid were achieved, ground improvement by simultaneous injection of the suspension and solution was possible, integrating the fine-grained soil areas where the infiltration and consolidation of suspended particles was difficult or the areas that did not penetrate well with the high-strength consolidated mass in the excavated area.

[0091] It was found that gelation occurred whether the bleeding rate was above 50% or below 50%, and that the bleeding liquid penetrated the sand gel, resulting in a composition that allowed the sand gel to stand on its own. The minimum strength at which the sand gel could stand on its own was 2.0 kN / m 2 The strength of the self-standing sand gel, which was made with only 75g of slag and 100mL of No. 1 water glass per 400mL, was 15kN / m on the 28th day. 2 The strength was also measured on the first and seventh days. The strength on the first day was 2.0 kN / m 2 On the 7th day, the strength was 10 kN / m 2 A similar trend was also observed with Toyoura sand. Furthermore, if salts such as Ca, Mg, and Al are included in the bleeding solution, the strength of the sand gel can be expected to increase further (Figures 12 and 13).

[0092] In this invention, the test specimen is adjusted to the size of the specimen used in the uniaxial compression test of soil, and the diameter D0 (mm) is usually 35 mm or 50 mm, and the height H0 (mm) is 1.8 to 2.5 times the diameter D0 (mm). As long as it is a self-standing sand gel, it can be judged at any age. Figure 10 shows the test conditions. From this, it can be seen that even in-situ sand can achieve a strength of 2.0 kN / m at an injection rate of 40%. 2It was found that if the strength of the improved ground is obtained, the soil will be self-sustaining. 3 The injection volume per injection is 0.4m 3 This becomes:

[0093] The gel time was shortened by increasing the amount of slaked lime added, and the strength increased with increasing the amount of slag. In Comparative Example 1, the solidified portion solidified, but the bleeding portion did not gel. The bleeding liquid of Example 36 gelled. It was found that the bleeding liquid also gelled when either or both of silica colloid and water glass were used.

[0094] (Relationship between silica concentration and strength) A neutral to alkaline solution was placed in an acrylic mold with a removable bottom and allowed to solidify. The homogel was checked for gelation and the self-supporting ability of the gel at different silica concentrations. The same procedure was also performed on the sand gel, and the solidification and self-supporting ability of the consolidated sand were checked. The results are shown in Table 9.

[0095] At silica concentrations below 0.5%, the homogel and sand gel did not become self-supporting. Further tests showed that gelation occurred even at a silica concentration of 0.25%, but the gel did not become self-supporting, and the sand gel did not solidify or become self-supporting (Table 9).

[0096] [Table 9]

[0097] Even if the entire amount of bleeding liquid did not gel, the sand gel remained self-supporting even when it gelled in the bleeding liquid and was tilted in the same way without collapsing (Figure 8). In other words, simply gelling the bleeding solution did not result in self-supporting homogels or sand gels (Table 8). It was found that certain conditions were necessary for the homogels and sand gels to become self-supporting.

[0098] Furthermore, penetration tests using a one-dimensional penetration device (2 m long) revealed that in a water glass-slag system, the bleeding liquid gels and the gel has enough strength to stand on its own, but that if water glass is not included, the bleeding liquid does not gel. Furthermore, whether the bleeding rate is above or below 50%, the bleeding liquid gels, resulting in a composition in which the sand gel penetrated by the bleeding liquid can stand on its own. In this case, the silica concentration of the bleeding liquid was predicted to be above 0.5%, between 0.5 and 2% (Table 9).

[0099] Furthermore, penetration tests confirmed that in the water glass-slag system and the suspension that did not contain water glass, the bleeding liquid penetrated and solidified into the sand, which the suspended particles from the bleeding liquid could not penetrate in the suspension that contained water glass. Therefore, this bleeding liquid is capable of penetrating even in ground that follows the particle size accumulation curve of solution-type penetration consolidation, and it was found that the penetration potential of solution-type silica grout can be achieved (Figure 9).

[0100] In this way, suspension grout uses particulate silica such as slag or fly ash and solution-type silica, allowing the bleeding liquid to penetrate and solidify in areas where suspensions cannot penetrate. Therefore, we focused on the gelation of the bleeding liquid and discovered the following conditions under which the bleeding liquid and sand gel can become self-sustaining.

[0101] In view of the above, other preferred embodiments of the present invention are as follows. This injection method involves injecting a consolidation agent consisting of a suspension of silica particles (e.g., slag or fly ash) with solution-type silica as the active ingredient into the ground through multiple injection holes to achieve interparticle consolidation. As the consolidation agent's bleeding liquid gels, the resulting homogel develops the strength to support itself. The bleeding liquid penetrates into areas of the ground that the suspension could not penetrate, expanding the consolidation area or integrating with the areas of the ground that the suspension penetrated. This allows the suspension particles from adjacent injection holes to connect with each other and form a larger, integrated consolidation body (Figure 13). Furthermore, adding CMC, MC, polyacrylamide, or clay to the injection liquid reduces dispersion in the ground and reduces dilution, even in gravel. Furthermore, using suspensions containing solution-type silica, such as water glass or silica colloid, can penetrate and consolidate areas that suspended particles cannot penetrate.

[0102] Here, in the above, the bleeding liquid gelling and the resulting homogel being self-supporting means that the silica concentration of the bleeding liquid is 0.5 w / v% or more, and the homogel is self-supporting without collapsing even when tilted diagonally within the mold.

[0103] In addition, the sand gel is self-supporting when the silica concentration of the bleeding liquid is 0.5 w / v% or more, and the sand gel is made by mixing No. 6 silica sand with the bleeding liquid to a relative density of 60% and has a diameter of 5 cm and a height of 10 cm. The strength of the sand gel measured in the uniaxial compression test is 2.0 kN / m 2 This means that it is more than or equal to this.

[0104] As mentioned above, the sand gel produced by bleeding silica grout, which is made from water glass and silica particles containing calcium, increases in strength over time (Table 8). This is thought to be because the calcium ions in the silica particles continue to dissolve into the bleeding liquid gel over a long period of time after gelation and react with the silica, forming calcium silicate, which contributes to the increase in strength. Alternatively, the added hardener containing calcium and magnesium may react with the soluble silica in the silica particles over a long period of time through pozzolanic action, resulting in an increase in strength due to the hydration reaction.

[0105] As described above, in this invention, the penetration and consolidation range can be set by adjusting the size of the consolidation bodies, the suspended particles, and the gelation of the bleeding liquid, depending on the ground conditions and the purpose of ground improvement (strength, range of consolidation area, etc.). Furthermore, the penetration and consolidation range of the suspended particles and the bleeding liquid can be set by adjusting the type and particle size of the silica particles in the suspension, the blending amount, the hardener and alkali agent, the type and amount of solution-type silica, the bleeding rate, the bleeding strength, and the gelation time. As a result, as shown in Figure 13, a new concept of simultaneous combined injection of suspension and solution was created, making ground improvement using suspension grout possible.

[0106] Furthermore, according to the present invention, by using as the main material for the consolidation agent natural or artificial silica particles, calcined silica, silica particles with natural pozzolanic properties, or fluidized soil made by turning on-site soil into a slurry, the weight of the consolidation body is reduced, the range of penetration and consolidation is expanded, and a ground improvement method that contributes to the global environment by reducing CO2 emissions is made possible.

[0107] As described above, the inventors have focused on the fact that a silica-rich suspension solidified body forms around the periphery of a suspension containing solution-type silica and primarily composed of silica particles, connecting adjacent solidified bodies. While the frequent bleeding of suspensions has traditionally been considered a drawback, in this study, we focused on the fact that the bleeding liquid can penetrate between soil particles that suspended particles cannot penetrate, and conducted research into the gelation of the bleeding liquid. As a result, we found that the gelation and strength of the bleeding liquid itself, the permeability of the bleeding liquid into sand, and the strength of the sand gel significantly affect the improvement of the penetration and consolidation properties of suspension grout. Based on these findings, we have identified the conditions for the penetration and gelation of the bleeding liquid into areas where suspended particles could not penetrate, the homogelation of the bleeding liquid, and the strength of the sand gel, and have invented a new ground improvement method based on the concept of simultaneous combined injection of suspension and solution.

[0108] In addition, the present invention provides a ground consolidation method that can be expected to reduce CO2 emissions by using a non-cement based ground consolidation material whose main component is slag, thereby obtaining a solidified body with excellent durability.

[0109] The radiation-shielding grout can be made by mixing the above-mentioned particles having radiation-shielding properties with the above-mentioned binder to form a hydrous gel. The binder containing the particles having radiation-shielding properties can be injected in the same manner as the binder injection. Therefore, the injection of the binder provides high strength against air raids, a water-stopping effect to prevent the infiltration of water containing radiation into the space, and a radiation-shielding solidified material, all of which can protect underground structures having underground spaces.

[0110] The binder of the present invention has, in particular, the following properties: (1) By setting the formulation of a suspension mainly made of silica particles with small particle size, light weight, and good fluidity, it is possible to achieve widespread penetration (Figures 5 to 7). (2) The inclusion of solution-type silica causes the bleeding liquid to gel, penetrating into the fine particle areas where silica particles cannot penetrate (Figure 4, Figures 6-8), causing the fine particle areas to solidify and become self-supporting. Since the bleeding liquid has the same permeability as solution-type silica grout, the fine soil permeability range shown in Figure 9 can be expected. Figure 2 shows the situation in which a silica suspension containing silica solidifies and the bleeding liquid gels when left to stand. Figures 3 and 5 show the situation in which a silica suspension not containing silica solidifies only the suspended matter and the bleeding liquid does not gel when left to stand. (3) The self-sustaining properties of homogel, solidification of sand gel, and self-sustaining properties of consolidated sand at low silica concentrations of solution-type grout are shown (Table 9). (4) From the particle size distribution of the sand used in the infiltration test (Fig. 12), it can be seen that the suspended particles used in the present invention infiltrate and solidify into the sandy ground.

[0111] The particle size distribution of the sand used in the infiltration tests (Figures 4–7) was No. 6 silica sand, as shown in Figure 12. With this particle size distribution, suspended particles can penetrate between soil particles up to 80 cm (Figures 6 and 7). With Toyoura sand, a finer soil, the penetration distance was approximately half that. Furthermore, when using the above suspension containing solution silica, the penetration range (Figure 9) was achieved, which is the same as the particle size range for the solution type. Although the penetration distance varies depending on the soil conditions, it is possible to form an improved structure as shown in Figure 13. Figures 13(c) and (d) are plan views of the infiltration solidified structure. The type and size of silica particles in the suspension can be selected depending on the soil conditions. Furthermore, the ability to infiltrate, as shown in Figure 13(d), allows for the stabilization of surrounding structures without damaging buried underground structures. Furthermore, by strengthening and waterproofing the surrounding ground, it is possible to strengthen underground structures with open spaces.

[0112] As described above, the inventors discovered that when a suspension containing solution-type silica and silica particles as its main component is injected, the area near the center becomes a high-strength region with a high concentration of suspended particles, while the strength of the suspended particles decreases with distance from the center, resulting in a low-strength region (Figures 6, 7, and 13). However, outside of this, silica-rich solidified bodies form due to gelation of the solution-type silica bleeding liquid, connecting adjacent solidified bodies. While extensive bleeding in suspensions has traditionally been considered a drawback, in this study, we focused on the fact that the bleeding liquid can penetrate between soil particles where suspended particles cannot penetrate, and conducted research on the gelation of the bleeding liquid. As a result, we found that the gelation and strength of the bleeding liquid itself, the permeability of the bleeding liquid into sand, and the strength of the sand gel significantly affect the improvement of the penetration and consolidation properties of suspension-type grout. Based on these findings, we investigated conditions that not only enable the suspension to penetrate into the surrounding ground, but also enable the bleeding liquid to penetrate and gel into fine-grained soil areas where suspended particles cannot penetrate, thereby forming large solidified bodies.

[0113] In suspensions that do not contain silica solution, the bleeding liquid does not gel, and the sand that has been permeated with the bleeding liquid does not become self-supporting and does not achieve sufficient strength (Figures 3 and 5). However, sufficient strength cannot be achieved simply by gelling the bleeding liquid (Table 9). Based on these findings, we discovered that the condition for the strength required for the self-supporting homogel and sand gel of the bleeding liquid is a silica concentration of 0.5 w / v% or higher (Table 8). This is considered to be penetration and solidification using solution-type silica. As a result, we discovered the conditions for the penetration and gelation of the bleeding liquid into areas where suspended particles could not penetrate, and the strength of the homogel and sand gel of the bleeding liquid. This led to the invention of a new ground improvement method based on the concept of simultaneous combined injection of suspension and solution.

[0114] The present invention also provides a ground consolidation method that can be expected to reduce CO2 emissions by using a non-cementitious ground consolidation material whose main component is silica particles with natural pozzolanic properties, including artificially calcined silica such as slag or fly ash, or soluble silica such as loam soil, thereby obtaining a solidified body with excellent durability.

Claims

1. A ground injection method for protecting a concrete structure buried underground and having an underground space from air raids, comprising: A ground injection method characterized by injecting the following ground consolidation material (A) and / or (B) into the periphery of the concrete structure from multiple injection pipes inserted into the ground, thereby reinforcing the concrete structure. (A) A suspension grout containing silica particles as the main material and one or more of a hardener, an alkali agent, and solution-type silica as active ingredients. (B) Non-alkaline silica grout.

2. 2. The ground grouting method according to claim 1, wherein the ground consolidation material contains radiation shielding particles and is used to protect the concrete structure from an aerial bombardment by a nuclear missile.

3. 2. The ground grouting method according to claim 1, wherein the solution-type silica is silica colloid and / or water glass, and the bleeding liquid of the ground consolidation material gels.

4. 2. The ground grouting method according to claim 1, wherein the silica particles contain one or more of calcined silica, natural silica having pozzolanic action, and hardenable silica particles as active ingredients.

5. 5. The ground grouting method according to claim 4, wherein the fired silica is made of one or more of slag, fly ash, cement, sewage incineration ash, plant incineration ash, and fired clay.

6. 5. The ground grouting method according to claim 4, wherein the natural silica having pozzolanic activity is one or more of loam soil, shirasu, volcanic ash, niwado and sanwado.

7. The ground injection method according to claim 1, wherein the alkaline agent is any one or more of the following (1) to (3): (1) An alkaline agent containing one or more of gypsum and MgO as active ingredients. (2) An alkaline agent containing one or more of Ca salts, Ma salts, Al salts, carbonates, and bicarbonates as active ingredients. (3) An alkaline agent containing one or more of lime, cement, caustic alkali, water glass, and silica colloid as active ingredients.

8. The silica particles have a Blaine value of 4,000 to 20,000 cm ２ 2. The ground grouting method according to claim 1, wherein the silica particles are used in an amount of 50 to 150 L / 400 L. / g.

9. The ground grouting method according to claim 1, wherein the silica particles are slag, and the amount of the slag in the ground consolidation material is 10 to 25% by mass when no cement is used, and 10 to 30% by mass when cement is used.

10. 4. The ground grouting method according to claim 3, wherein the molar ratio of the water glass is 1.0 to 5.0, and the amount of the water glass mixed in the ground consolidation material is 10 to 150 L / 400 L.

11. 11. The ground injection method according to claim 10, wherein the ground consolidation material is a suspension containing the silica particles as a main component and the solution-type silica as an active ingredient, and the ground consolidation material is injected into the ground from the plurality of injection pipes, The bleeding liquid of the ground consolidation material gels, and the homogel has a strength to stand on its own, and the sand gel solidified by the penetration of the bleeding liquid has a strength to stand on its own, A ground injection method characterized in that the bleeding liquid penetrates into parts of the ground that the suspension could not penetrate, expanding the solidification range, or integrating with the parts of the ground that the suspension has penetrated to form a solidified body. Here, in the above, the bleeding liquid gelling and the resulting homogel being self-supporting means that the silica concentration of the bleeding liquid is 0.5 w / v% or more, and the homogel is self-supporting without collapsing even when tilted diagonally within the mold. The sand gel being self-supporting means that the silica concentration of the bleeding liquid is 0.5 w / v% or more, the sand gel is prepared by a mixing method using No. 6 silica sand and the bleeding liquid so as to have a relative density of 60% and has a diameter of 5 cm and a height of 10 cm, is self-supporting, and the strength in a uniaxial compression test measured using the sand gel is 2.0 kN / m ２ This means that it is more than or equal to this.

12. 2. The ground injection method according to claim 1, wherein the soil consolidation agent is formulated to provide a lightweight, low-alkali, and low-carbon type ground improvement agent.

13. 2. The ground grouting method according to claim 1, wherein the ground consolidation material contains one or more of microbubbles, air, a dispersant, and a thickener as active ingredients.

14. 2. The ground grouting method according to claim 1, wherein the hardener is a polyvalent metal compound, which is one or more of hydroxides, oxides or salts of Ca, Mg or Al, and / or gypsum.

15. 2. The ground injection method according to claim 1, wherein the improvement effect of the injection of the ground consolidation material is confirmed by a non-destructive test.

16. 16. The ground grouting method according to claim 15, wherein the non-destructive testing is performed by elastic wave velocity logging, acoustic tomography, or surface wave exploration.

17. A ground consolidation material used in the ground injection method described in claim 1 to protect concrete structures buried underground and having underground spaces from air attacks by nuclear missiles, characterized in that the ground consolidation material contains radiation-shielding particles.

18. 18. The ground consolidation material according to claim 17, which comprises (B) non-alkali silica grout having a pH of 1 to 10, and contains one or more of silica colloid and water glass, and one or more of acids and salts as reactants as active ingredients, and when the (B) non-alkali silica grout comprises silica colloid, water glass, and acid, the ratio of the silica concentration due to silica colloid to the silica concentration due to water glass is 100:0 to 0:100, the silica concentration is 0.4 to 40 wt%, the molar ratio of silica is 2.0 to 100, and the gelation time is from instantaneous setting to 10,000 minutes.

Images