JP5015193B2 - Ground injection material and ground injection method - Google Patents

Description

  The present invention relates to a ground injecting material and a ground injecting method, and more particularly, using a silica solution containing silica sol produced from metallic silicon as an active ingredient, injecting it into the ground or rock, permanently fixing the ground, It is a ground-injecting material and ground-injecting method that has excellent permanence and environmental conservation for high-osmotic water pressure, and can achieve high permeability and water-stopping effect by using it for anti-chemical construction method and rock injection method. As a result, it has become possible to dramatically expand the field of application of ground injection materials.

  Conventionally, a ground injection material using a silica solution has been used for temporary construction because durability cannot be obtained. However, in recent years, the present applicant has developed a permanent grout material using activated silica obtained by subjecting water glass to ion exchange treatment using an ion exchange resin or ion exchange membrane, or a colloidal silica colloid. It was done. For this reason, permanent ground improvement can be improved by using the ground itself as a raw material by the method of pouring, and in the future, it is desired to expand the application field in the ground pouring method.

  On the other hand, in recent years, the prevention of dam revetment, liquefaction measures near the coast, injection of rock cracks in dams, underground dams, tunnels, etc., containment of radioactive waste in underground cavities, storage in underground cavities such as LPG, etc. In order to fill fine cracks in the rock mass, tunnel excavation directly under the residential area, liquefaction countermeasures directly under the building, etc., it is required to improve the strength ground by using a grout with high permeability, water-stop and environmental conservation.

  Conventionally, various solution-type silica grouts using water glass as a raw material are known as grouts generally used for ground improvement such as soft sand ground. For example, water glass alkaline grout, grout mainly composed of acidic water glass, grout mainly composed of active silica obtained by treating water glass with cation exchange resin or ion exchange membrane, and concentrated granulation of active silica And a weakly alkaline and stable silica sol having a pH of 9 to 10 (Patent Documents 1 and 2).

However, in the above-mentioned solution-type silica grout, in the storage of rock cavities such as LPG, storage of rock cavities for waste disposal such as nuclear power generation, storage of rock cavities of CO ₂ or containment of harmful substances including toxic metal salts, etc. There is room for improvement in the penetration and consolidation of fine cracks, and after injection, the gel between the soil particles or the silica gel in the cracks in the rock mass is pushed out by water pressure, reducing the water stoppage and long-term durability. There was a risk that the constructed cavity was filled with osmotic water, or the stored harmful substances were eluted to the outside. In addition, hollow storage such as bedrock is made of silica ²⁺ , Mg ²⁺ contained in the bedrock groundwater, or silica injected due to the presence of various ions such as Na ⁺ , K ⁺ , Cl ⁻ and SO ₄ ^{2− in} seawater. There was a possibility that heterogeneous silica was precipitated by reaction, and it was likely to be clogged between rock cracks and soil particles, impeding the penetration of the injected solution.

  Therefore, as an improved technique for such a point, ultrafine particle cement is used, or as described in Patent Document 3, silica grout contains silica colloid having a particle diameter of 6 to 50 nm and fine particle cement as active ingredients. Has been proposed. As a result, the present applicant has disclosed a ground injection method that retains water-stopping and strength over a long period of time even when the consolidated ground with silica grout is under osmotic pressure.

Japanese Patent No. 3205900 JP 2004-35584 A JP 2006-226014 A

  However, in recent years, in the case of hollow storage of nuclear waste, LPG, carbon dioxide gas, etc., or in the soil fixation of soil contaminants, a permanent water stop function is required to prevent the storage and harmful substances from eluting into the groundwater. It is done. Therefore, even when using a fine particle cement or the like of the method described in Patent Document 3, etc., it is possible to stop water to some extent in rock crack injection, but it is difficult to penetrate into fine voids, and improved. There was room for.

  In addition, it has been proposed to use a ground injection material mainly composed of a silica solution. However, if the groundwater contains salt, metal ions, etc., such as the ground near the coast or the rocks such as granite, the silica solution in the alkaline region. In this case, partial gelation occurs, or the gelation time is shortened and the grout permeability to the ground having fine cracks is lowered, and the expected water stop effect may not be obtained. For this reason, it has been proposed to use cement together to maintain strength and increase water-stopping properties, but due to the salt of calcium, magnesium, etc. in the cement, a rapid partial gel of the injecting material is generated and the permeability is low. There is a problem that the gel once formed by the alkali component in the cement is dissolved and dissolved.

In addition, conventional silica sol uses water glass as a main raw material, and ion exchange treatment with an ion exchange resin, an ion exchange membrane or the like to remove Na ₂ O to produce low-molecular active silica, and further increase the particle size. Therefore, a sufficient effect on the above-mentioned problem cannot be obtained.

  Therefore, the object of the present invention is to solve the problems in the prior art by using a silica sol produced from metallic silicon, and has excellent durability and environmental conservation in rock mass injection having cracks against high osmotic water pressure. It is providing the ground injection material and ground injection method which have high permeability and a water stop effect.

  As a result of intensive studies to solve the above problems, the present inventors have found that a ground injection material for performing permanent ground improvement in the same position without moving the soil particles themselves, and a ground using the same. It has been found that the following requirements (1) to (8) are necessary to obtain the injection method.

(1) The elution of silica from the gelled material is small for many years.
(2) The injected gel is between rock cracks and soil particles and has high extrusion resistance even under water pressure.
(3) The gelled product solidified against alkali such as cement grout to be used together does not deteriorate.
(4) It has a low viscosity and a long gel time, and can penetrate into finer particles to form a large solidified body.
(5) Even in the presence of ions such as Ca ²⁺ , Mg ²⁺ , Na ⁺ , K ⁺ , in the groundwater from seawater or bedrock, it permeates between fine rock bed cracks and soil particles, and its gelled product Get high water tightness without being pushed out by water pressure.
(6) It should be gelled in a neutral region and not contaminate groundwater.
(7) It should be gelled normally with a small amount of the reactant used, forming a gelled product with excellent durability, resulting in less reaction products and no contamination of groundwater.
(8) Do not adversely affect underground structures such as concrete and metal.

  Under the above conditions, (1) to (3) relate to long-term durability (permanence), (4) to (5) relate to penetrability, and (6) to (8) relate to environmental conservation.

  The present inventors have found that silica sols produced from metallic silicon are all superior in the above conditions, compared to silica sols (colloidal silica) obtained by ion exchange using ion exchange resins and ion exchange membranes that have been used conventionally. As a result, the present invention has been completed.

That is, the ground injection material of the present invention is a ground injection material containing a silica solution,
The silica solution contains silica sol produced from metallic silicon as an active ingredient, Na ₂ O is in the range of 0.1 w / w% to 4.0 w / w%, and the pH is 1 to 11, and The silica concentration is 1 to 75 w / v%. Further, the silica sol is increased in size to form a colloidal shape in which the silica is polymerized and the colloid has a particle size of 1 to 100 nm, particularly 5 to 100 nm.

  In the ground injection material of the present invention, it is preferable that the silica solution contains, as an active ingredient, one or more selected from the group consisting of acids and salts in addition to the silica sol. Furthermore, the silica solution preferably contains water glass and an acid and / or salt, and more preferably the acid is phosphoric acid. Furthermore, when the silica concentration of the silica sol is set to 1 to 75 w / v% according to the uniaxial compressive strength required after the construction or when water glass is used in combination, the silica concentration derived from water glass is 0 to 95% of the total silica concentration. It can also be an active ingredient.

  Moreover, it is preferable that the ground injection material of this invention exhibits the pH of the said silica solution 4-9 by ion-exchange-treating the said silica solution.

Furthermore, the ground injection material of the present invention preferably contains at least one selected from the group consisting of slag, polyvalent metal compounds, alkali metal salts, alkaline compounds, sequestering agents and organic compounds.

The ground injection method of the present invention is a ground injection method for injecting the ground injection material into the ground.
The groundwater in the ground contains one or more selected from the group consisting of seawater, calcium and magnesium. The ground injection method of the present invention can be solidified reliably even if the groundwater in the ground contains seawater, calcium and magnesium.

  In the ground injection method of the present invention, the ground injection material is injected into the ground below the groundwater level to form a water-stopping layer, containing waste or soil contaminants, or containing gas, liquid fuel, or waste. It is preferable to construct a cavity or tunnel for storage. According to the ground injection method of the present invention, even if gas or liquid fuel is stored, gel is not pushed out by water pressure in the cavity, and a space is formed and the components of the stored substance stored in the cavity are not eluted to the periphery. Sealed in the cavity. Moreover, it is suitable for fixing the waste or the soil contaminants in the ground and maintaining the sealing effect of bentonite without degrading bentonite when these are covered with bentonite.

In addition, another ground injection method of the present invention is a ground injection method for injecting the ground injection material into the ground.
Before or after injecting the ground injection material into the ground, a ground injection material containing cement or slag as an active ingredient is injected into the ground.

Furthermore, the other ground injection method of the present invention is a ground injection method for injecting the ground injection material into the ground,
The ground injection material is injected into the ground under high water pressure.

Furthermore, the other ground injection method of the present invention is a ground injection method for injecting the ground injection material into the ground,
The ground injection material is injected into the ground to improve the permanent ground or prevent liquefaction.

  The ground injection method of the present invention is a permanent material with low viscosity and long gelation time by injecting the ground injection material, which is prepared by adjusting the silica concentration and gelation time according to the uniaxial compressive strength required after construction. It is possible to improve the permanent ground economically or to prevent liquefaction by making an improved body with a large consolidated diameter excellent in.

  By using colloidal silica produced from metallic silicon as an injection material according to the present invention, liquefaction of the ground, water stoppage and suction of the ground and bedrock, and high rock water pressure, particularly in rock injection with cracks, It has excellent durability, maintains long gelation time and low viscosity, even in groundwater containing salt and metal ions, and in the ground of almost neutral region. It has become possible to provide a ground injection material and a ground injection method that can form a normally durable gelled product and obtain high permeability and water-stopping effect and environmental conservation.

Hereinafter, embodiments of the present invention will be specifically described.
The ground injecting material (hereinafter also referred to as “injecting material”) of the present invention is characterized by containing silica sol (including silica colloid) produced from metallic silicon (silicon) as an active ingredient.

(About silica sol manufactured from metallic silicon)
In the present invention, the method for producing silica sol from metallic silicon is not particularly limited. For example, US Pat. No. 2,614,995 discloses a method for producing a silica sol from metallic silicon, US Pat. No. 2,473,260 which discloses a method for producing tetramethyl silicate from metallic silicon, and silica sol (silica Japanese Patent Laid-Open No. 6-316407, which discloses a method for producing a colloid), can also be used for reference.

  The present invention provides a conventional water glass by injecting a ground injecting agent containing a silica solution containing silica sol (hereinafter also referred to as “metallic silicon silica sol”) produced from such metal silicon into the ground. As compared with silica sol (silica colloid) obtained by ion exchange treatment, it has been found that it exhibits extremely superior characteristics. The reason is not clear, but it seems that the metal silicon silica sol has less alkali than the silica sol obtained by ion exchange treatment of the conventional water glass, and the colloidal particles themselves are dense and less reactive. For this reason, it seems that the strength is high and a long gelation time is obtained even in the neutral region.

Thus, when producing a silica sol from metallic silicon, since it is stabilized by adding a minimum amount of Na ₂ O, the content of Na ₂ O is smaller than that of a silica sol obtained by conventional ion exchange treatment, and the acid adjusting material The pH can be adjusted even if the amount used is small. Further, by removing Na ₂ O from the metal silicon silica sol with an ion exchange resin, a silica sol having a pH of around 4 to 9 stabilized for several days to several months can be obtained. As a result, a long gelation time can be obtained in a neutral region with a small amount of added reagent, and a ground improvement with excellent permanentness and economy can be achieved with a large consolidated diameter by an injection material. There are few sexual reaction products, and ground improvement with high environmental conservation can be performed without contaminating groundwater.

  The metal silicon silica sol used in the present invention is a weakly acidic to weakly alkaline silica colloid having a particle diameter of 1 to 100 nm. Further, pH 4 to 9 obtained by treating the metal silicon silica sol with an ion exchange resin or an ion exchange membrane, or water glass, active silica, acid or salt, water glass and acid mixed with the metal silicon silica sol. The obtained acidic water glass, ion exchange treated water glass (active silica, activated silicic acid) produced by ion exchange treatment of water glass, silica sol obtained by adding a silica sol which has been further granulated and stabilized in a weak alkaline region, etc. It is.

Since the silica solution in the present invention is weakly alkaline and stabilized and contains almost no Na ⁺ , the pH is usually 11 or less, indicating a weak alkalinity of 1 to 11, and Na ₂ O ranges from 0.1 w / w% to 4. It is in the range of 0 w / w%. When Na ₂ O exceeds 4.0 w / w%, the silica colloid dissolves and becomes an aqueous solution of silicate. On the other hand, when Na ₂ O is less than 0.1 w / w%, the silica colloid is unstable and easily aggregates. That is, when Na ₂ O is in the range of 0.1 w / w% to 4.0 w / w%, Na ions can be distributed on the surface of the silica colloid to maintain a stable colloidal shape. Further, the silica solution according to the present invention once has Na ₂ O stabilized in the range of 0.1 w / w% to 4.0 w / w%, and then further removed Na ₂ O by ion exchange treatment, _{When 2} O is 0.1 w / w% or less, a stable silica colloid solution can be produced.

  The metal silicon silica sol prepared in this way is almost neutral and semi-permanently stable. When this is used as an infusion solution, it is gelled during delivery from the factory to the site and during the infusion operation. There is no worry to do. Even if the silica solution containing the metal silicon silica sol is poured into the ground as it is, it does not gel within a practical time itself, so that a practical consolidation effect cannot be obtained.

Also, soil injection material containing silica solution to the silica sol of the present invention as an active ingredient may also contain further silica content of water glass _{(SiO 2) 1~75w / v%} . Water glass contains many silanol groups and has high reactivity, so that the initial strength development is fast. However, it contains a larger amount of Na than silica sol, and the gelled product shrinks after gelation. Therefore, it is necessary to keep the above amount.

  Further, the injection material of the present invention is a group consisting of salt, acid, cement, slag, polyvalent metal compound, alkali metal salt, alkaline compound, sequestering agent, organic compound, active silica (active silicic acid) and water glass. It is preferable to contain 1 or more types selected from. Thereby, gelation time can be adjusted and permeability can be improved.

(About penetrability)
As is already known, cement has a large particle size and cannot penetrate into fine cracks in rock. Moreover, even in the silica-based grout in the alkaline region, the penetration and consolidation property to the fine crack of the rock is insufficient, the shrinkage after gelation is large, and long-term water stoppage is impossible. According to the inventor's research, the reason why the conventional silica sol has insufficient permeability of the silica solution to the rock mass is that Ca ²⁺ , Mg ²⁺ , Na ⁺ , K ⁺ contained in the rock mass infiltrated water and seawater. However, it was found that it reacted with the silica content of the silica-based grout to immediately form non-uniform silica agglomerates, which were interspersed between cracks in the rock mass and soil particles, thereby inhibiting the subsequent penetration of the silica solution. It has been found that the ground injection material of the present invention can have a low viscosity and excellent penetrability without generating a precipitate even under such conditions. In particular, a ground injection material containing silica sol, wherein the pH of the ground injection material is non-alkaline (pH 1 to 11), and the silica concentration is 1 to 75 w / v%, preferably the silica concentration is 6 to 40 w / It was v%, and more preferably 1-100 nm, especially 5-100 nm.

(About durability)
The gelled product of the conventional silica-based injecting material is weak against alkali. Especially when the fine cement is first injected and the large cracks are filled, then the silica-based injecting material is secondarily injected to fill the fine cracks. There was a problem that the eluate dissolves the gelled silica. It has been found that this problem can be prevented by using a metal silicon silica sol. This is probably because the colloidal gel is dense and grows to a large particle size during the gelation process. For this reason, it seems that these do not have a bad influence on the stability of the gelled product.

  Moreover, the ground injection method of this invention can solidify a ground by inject | pouring the ground injection material of this invention, and can have intensity | strength over a long period of time. Furthermore, by injecting such a ground injection material, it is possible to have water-stopping and strength over a long period of time under osmotic water pressure in the basement.

  Furthermore, the ground injection method of the present invention is a ground mainly composed of a rock having cracks under hydraulic pressure, the ground injection material of the present invention is injected into the rock, the cracks are filled with gel, and high penetration Even under water pressure, the gel can be retained for a long time without being pushed out. In addition, the ground injection method of the present invention, by injecting the ground injection material of the present invention, contains waste, carbon dioxide gas, etc. in the ground under rock seepage, in the rock or under the seabed, or gas or liquid fuel. It is possible to store or form a hollow water-stopping layer from which harmful substances do not elute to the outside.

(About additives)
The metal silicon silica sol can adjust the gelation time by adjusting the pH to be alkaline or acidic by using either an acid or a salt, or a combination thereof. The sequestering agent has a chelating effect and passivates metal ions dissolved in the groundwater from the rock mass and metal ions eluted from the crack in the rock mass. Examples of metal ions present in the groundwater or in the breathing water of the alkaline suspension of the primary injection material include Ca ²⁺ , Mg ²⁺ , iron ions, etc., and sequestering metal ions such as phosphoric acid and phosphate compounds. Agents (chelating agents, etc.) form a coating film with silica by masking the underground metal ions and react with calcium and magnesium in groundwater trace metals and shells to produce insoluble or poorly soluble compounds. It is guessed. For this reason, the Ca ^<2+> , Mg ^<2+> in a ground produces the effect that the penetration | infiltration of the ground injection material of this invention is not inhibited.

  Among phosphate compounds, condensed phosphates such as sodium hexametaphosphate form the strongest coating layer with non-alkaline silica on the concrete surface, but phosphoric acid also shows an excellent effect in the silica solution. This is probably because a condensed system is gradually formed and the same action as that of condensed phosphate is exhibited. The phosphoric acid compounds have examples described later, and all have the same effects as described above. Therefore, in the present invention, the phosphoric acid compound is treated as a sequestering agent having a chelating effect. As the sequestering agent, there are compounds described later in addition to the phosphoric acid compound. However, in the presence of silica, the phosphoric acid compound tends to form a strong coating on the concrete surface.

  When using a phosphoric acid compound other than phosphoric acid or a sequestering agent, other acid, for example, a compound exhibiting acidity such as sulfuric acid or sulfate can be used in combination.

When phosphoric acid is mixed with water glass, it neutralizes the alkali of the water glass to form an acidic silica solution, and forms a concrete coating film together with silica content and Ca ²⁺ and Mg ²⁺ on the concrete surface. It is possible to protect the concrete from SO ₄ ²⁻ and Cl ⁻ existing in. In addition, phosphoric acid and phosphoric acid compound form a protective film on the concrete surface as described above in the presence of sulfate ions.

  The phosphoric acid compound and / or chelating agent used in the present invention has a chelating effect, and examples thereof include phosphoric acid, various acidic phosphates, neutral phosphates, and basic phosphates. , Tetrapolyphosphates, hexametaphosphates, tripolyphosphates, pyrophosphates, acidic hexametaphosphates, acidic pyrophosphates, and the like, and the condensed phosphates are sodium salts As the phosphoric acid compound forming the non-alkaline silica solution, sodium hexametaphosphate is particularly preferable because it forms strong masking silica on the concrete surface. Examples of the chelating agent include ethylenediaminetetraacetic acid, nitrilotriacetic acid, gluconic acid, tartaric acid, and salts thereof in addition to the phosphoric acid compound. In the present invention, the phosphoric acid compound is present in the presence of a silica solution. Underneath forms the most effective coating (masking silica) on the concrete surface.

  Furthermore, in the present invention, as the salt, a monovalent alkali metal salt such as NaCl or KCl, a polyvalent metal salt such as Al, Ca or Mg, or a gelling material such as a hydroxide or other salt thereof is added. When the mixture is injected into the ground as a mixture, the ground injection material of the present invention bonds the colloidal particles destabilized by the gelling material in the ground to form a solid consolidated body, thereby solidifying the ground. .

  In the present invention, it is preferable that the method of filling the rock mass under the groundwater surface satisfies the following requirements. In any of the following cases, a silica solution containing metal silicon silica sol as an active ingredient exhibits characteristics superior to silica colloids obtained by conventional ion exchange treatment.

1. In the present invention, the metal silicon silica sol is prepared by adjusting a silica sol exhibiting weak alkalinity with an acid such as phosphoric acid or sulfuric acid, or an acid water salt obtained by mixing an acid, salt, water glass and acid, or active silicic acid. A non-alkaline acidic silica sol to which is added can be used. In tunnel construction, high osmotic pressure water may leak inside the tunnel. Therefore, tunnel excavation under high pressure water and permanent ground improvement for the purpose of deep underground development are subject to large earth pressure and water pressure on the excavation ground, and the excavation work takes a long time. It is necessary to increase the strength uniformly and to obtain a water stop effect and a consolidation effect over a long period of time. In addition, having excellent durability is also necessary to withstand the prolonged period from injection to excavation work, maintenance after the work is completed, and prevention of groundwater from filling. The ground injection material and the ground injection method of the present invention are used for such applications.
2. In the present invention, the metal silicon silica sol is injected in combination with the fine particle cement to form a highly durable gel with high resistance to extrusion of the cement.
3. In the present invention, even if groundwater contains any one or more of Ca ²⁺ , Mg ²⁺ , Na ⁺ , K ⁺ , the ground water is uniformly consolidated.
4). The ground injection material of the present invention can be used for rock injection of dams and tunnels, and for rock cavity water injection, to form a permanent water stop layer.
5. In the present invention, when forming a rock cavity, a water blocking layer is formed, and groundwater is unlikely to leak into the cavity. Therefore, a waste storage cavity, a fuel storage cavity such as LPG, a CO ₂ storage cavity, and a soil contaminant storage cavity are formed.

  In the present invention, the ground injection material containing the above-described metal silicon silica sol as an active ingredient and the suspension type injection material can be used together and injected into the ground. Examples of the suspension-type injection material include a suspension-type injection material containing fine particle cement, fine particle slag, or a mixture thereof as an active ingredient. By injecting these suspension-type injection materials (suspension solutions) into the ground in advance and filling rough cracks, even under osmotic pressure in the basement, the water stoppage and strength can be maintained for a long time. The ground can be improved.

  In the above, a suspension-type injection material containing fine particle slag as an active ingredient is injected into the ground in advance, and then a ground injection material mainly composed of the metal silicon silica sol of the present invention is injected into the injected ground. Can be used in combination. Moreover, after inject | pouring this ground injection material, this suspension type injection material grout is inject | poured. Both the suspension-type injection material and the ground injection material can be used in combination in the ground by alternately injecting the suspension-type injection material and the ground injection material a plurality of times.

  In addition, the ground injecting material of the present invention is used in the ground improvement method which is excellent in durability such as water stopping of ground under water pressure such as liquefaction prevention injecting and water pressure such as dam, rock, etc. A silica solution derived from water glass can be used together with the silica sol of the present invention according to the water permeability coefficient and uniaxial compressive strength required after the construction. The water permeability coefficient and uniaxial compressive strength can be suitably adjusted by adjusting the silica concentration derived from the metal silicon silica sol and water glass.

In order to make the ground injection material effective as a liquefaction countermeasure using water glass or as an injection material for permanent water stopping, it is preferable to set the mixture of water glass and silica colloid within the following range.
pH: 2-7
Silica concentration: 1 to 75 w / v%

  The non-alkaline silica solution containing the above silica contains silica sol, water glass, and acid as active ingredients, and these three components may be blended at the same time, or may be blended after mixing any of the silicas with silica. In addition, the above silica may be mixed in the acid respectively or simultaneously, or an acid water glass may be previously prepared by mixing an acid and water glass, and then mixed with a metal silicon silica sol. Alternatively, an acidic silica sol may be prepared by mixing a metal silicon silica sol and an acid and mixed with water glass.

  The ratio of silica sol (colloidal silica) and silica concentration in water glass in the case of blending at the above silica concentration is related to (A) volume change, (B) water permeability coefficient, and (C) uniaxial compressive strength change with time. Since the gelled product of the metal silicon silica sol has almost no volume change and no increase in water permeability coefficient, the water-stopping property is high, but the increase in uniaxial compressive strength is gradual. On the other hand, water glass has higher uniaxial compressive strength than metal silicon silica sol, but gel contraction due to volume change is observed, thereby increasing the water permeability coefficient. From the above, the smaller the ratio of water glass to silica sol, the smaller the strength, but the smaller the shrinkage rate and the less the strength decrease. However, in order to increase the strength over the long term, the greater the ratio of water glass, the greater the strength, but the greater the shrinkage rate and the lower the strength, so the strength converges to a constant value by containing the metal silicon silica sol. .

  Furthermore, in the present invention, when water glass and acid are added to metal silicon silica sol as described above, water glass and acid are mixed and added to metal silicon silica sol as acid water glass, or metal silicon silica sol and acid are added. By mixing the acidic silica sol containing and water glass, a composite silica sol in which a small colloid of 1 nm or less of acidic water glass is added to the metal silicon silica sol is formed. Accordingly, a composite silica colloid composed of three different particle sizes is formed.

  In the present invention, silica having a large particle size is low in strength for a high silica concentration and slow in onset of strength, but has a long-term water pressure resistance effect even under high osmotic water pressure. On the other hand, silica having a small particle size is excellent in strength development and cohesion even if the silica concentration is low. Moreover, since this invention is composite silica sol which consists of these mixtures, it can achieve reliably the water-stopping property and the firm consolidation effect which were excellent in the initial stage especially under high osmotic water pressure. For this reason, in this invention, a desired effect can be acquired, without mix | blending cement.

  The above-described composite silica sol according to the present invention has high reactivity and is hardly affected by alkalinity even when injected into a ground into which a suspension of fine particles exhibiting alkalinity is injected. Consolidation and water-stopping properties are expressed simultaneously. In particular, the composite silica colloid according to the present invention is used for rock rock crack injection under high osmotic water pressure, achieves a water-stopping property and a strong caking property with excellent long-term durability, and ensures that the ground to be injected is solidified water. To do.

  Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

  In the following, the characteristics in the case where a silica solution using a metal silicon silica sol and a silica sol obtained by a conventional ion exchange treatment are used as a ground injection material will be compared.

(Experimental example 1) Compounding test of silica sol produced from metallic silicon Using the silica sol produced from metallic silicon of the present invention, a compounding test was conducted under the compounding conditions per 1000 L shown in Table 1 below. Silica sol produced from metallic silicon used in Experimental Example 1 was manufactured by Jinan Silver Toyofuku Co., Ltd. (SiO ₂ : 30.3 w / w%, Na ₂ O: 0.35 w / w%, specific gravity 1.21. ) Was used. As the water glass, JIS No. 3 water glass was used. The pH and gel time (hours) were measured. Moreover, the same test was done using the metal silicon silica sol which passed the ion exchange resin. The results are shown in Table 2 below.

  From Example 1 and Comparative Example 2, a short gelation time could be obtained with the same potassium chloride addition amount by using metal silicon silica sol in the alkaline region. Further, from Example 2 and Comparative Example 3, it was possible to obtain a long gelation time with a small amount of acid by using metal silicon silica sol in the neutral region. Furthermore, from Example 3 and Comparative Example 4, a long gelation time could be obtained with a small addition amount by using metal silicon silica sol in the acidic region. Furthermore, from Example 5 and Comparative Example 1, it was possible to obtain a long gelation time with a small amount of acid compared to acidic water glass by using metal silicon silica sol.

  From Example 6, the ion-exchanged metal silicon silica sol having a neutral pH was stable for more than the latter half of the production. Further, from Example 7, the silica sol having a neutral pH obtained by ion-exchange treatment of weakly alkaline metal silicon silica sol was able to obtain a long gel time. Furthermore, from Tables 1 and 2, when Example 8 and Example 4 are compared, the amount of acid addition can be reduced by using ion-exchanged metal silicon silica sol even when the silica compound has the same blending amount and substantially the same pH. You can see that As described above, the silica solution using the metal silicon silica sol according to the present invention has a long gelation time in the neutral region, and therefore has good permeability and can adjust the gelation time with a small amount of a reagent. There was little sex reaction product, and the water quality was not contaminated.

(Experimental example 2)
The resistance of the injected material to water pressure was measured using a steel pipe simulating a rock fracture. The steel pipe had a length of 50 cm, a hole diameter of 1, 3, 5 mm, and an injection material prepared according to the composition shown in Table 1 was injected from one of the three pipes and cured at room temperature for 28 days. A water pressure of 5 MPa corresponding to a ground depth of about 500 m was applied to the gel cross section from the side of the apparatus, and the resistance to the water pressure was measured. The results are shown in Table 3 below.

  From the above Table 3, the following was found. In Examples 1 to 4 and 7 and Comparative Example 2 having the formulations shown in Table 1 above, water resistance was exhibited in each of 1, 3, and 5 mm, and water was stopped. On the other hand, in Example 8, although resistance was exhibited at 1 and 3 mm, water was passed through at 5 mm. In Comparative Example 1 which is a conventional water glass-based injection material, all water was passed. For these reasons, the metal silicon silica sol is formed from a colloid that is structurally more solid than the conventional silica sol, so that there is no volume reduction in water pressure, and it is difficult to create a gap between the steel plate and the metal plate. It is considered that the metal silicon silica sol is excellent in resistance to water pressure.

(Experimental example 3)
In order to confirm the water stoppage in the presence of breathing water in the primary injection material or in the presence of groundwater containing a large amount of calcium or magnesium, breathing water or seawater is used in the steel pipe for the initial injection as shown in the following table 4. After filling, the injection was carried out by changing 300 mL of the injection material as the late injection material, and the same experiment as in Experimental Example 2 was performed. The formulation used is shown in Table 4 below. The resistance to water was up to 1, 3, 5 mm. As the breathing water, Portland cement was mixed at a water powder ratio of 6: 1, and the supernatant water after standing for 1 day was used. Seawater used was artificial seawater for raising tropical fish.

  In the presence of breathing water, Example 1 which is a compound in the alkali region of the metal silicon silica sol of Experiment 3-1 showed resistance up to 1 mm and 3 mm, whereas in Experiment 3-5, the conventional silica sol The formulation of Comparative Example 2 was gelled when contacted with breathing water and did not pass water. From this, it was found that in the case of the blending of Example 1, the metal silicon silica sol is less susceptible to breathing water even in the alkaline region than in the case of the blending of Comparative Example 2. Since resistances obtained up to Experiments 3-2, 3-3, and 3-4 were obtained up to 5 mm, the metal silicon silica sol was stable in the middle to acidic region, and was affected by the primary injection breathing water. As a result, it was found that the permeability was high and the water stop strength was obtained.

In the presence of seawater, the composition of the metal silicon silica sol of Experiment 3-6 in the alkali region showed resistance up to 3 mm, whereas the compound of the conventional silica colloid of Experiment 3-10 in the alkali region was When it came into contact with seawater, it gelled and did not pass through. From this, in the case of the blending of Example 1, it was found that the metal silicon silica sol was less affected by seawater even in the alkaline region as compared with the blending of Comparative Example 2. Since the resistances up to 5 mm were obtained in Experiments 3-7, 3-8, and 3-9, the metal silicon silica sol was stable in the middle to acidic region as shown in Experimental Example 1, so As a result, it was found that the permeability is high and the water stop strength can be obtained. In addition, even in the presence of metal ions such as seawater, rock infiltrated water, and K ⁺ , Na ⁺ , Mg ²⁺ , Ca ^2+, etc. caused by cement grout, it can penetrate into the ground without causing clogging in the ground. It has been found that it is difficult to impede, and easily penetrates into fine rock cracks and fine-grained soil.

(Experimental example 4)
Metallic silica silica sol, water glass, activated silica, ion exchange treated water glass produced by ion exchange treatment of water glass, acid water glass obtained by mixing water glass and acid, water glass and activated silica were increased in size. By mixing a silica compound such as a granulated silica colloid or the like, a large colloidal silica molecule and a small silica molecule such as water glass are combined, thereby increasing the initial strength. However, when these are mixed, they may become cloudy and precipitate due to a mixture such as Na ₂ O other than silica contained in the silica compound. It is considered that the colloid in the metal silicon silica sol is adsorbed and increased in particle size by the sodium in the water glass, so that the silica settles without being dispersed in the solution. As a ground injection material for ground improvement, a water stopping effect can be obtained even if precipitation occurs, but it is more preferable that the colloid particle size increases and does not settle even if it becomes cloudy and penetrates the ground. It is considered that a better water stop effect can be obtained by increasing the diameter. Then, as a result of examining the formulation by the present inventors, the following was found.

As a blending method, a silica compound is added to a metal silicon silica sol adjusted to a weakly acidic to acidic side, or, on the alkali side, the mixing ratio of the metal silicon silica sol and the silica compound is a molar ratio n (= mass ratio (SiO ₂ w / v% / Na ₂ Ow / w%) × 1.032) is 4 or more, and when the silica concentration is 20 w / v% or more and 75 w / v% or less, the molar ratio n is 15 or more, and the silica concentration is 15 w / v% or more. When the ratio is less than 20 w / v%, the molar ratio n is preferably 10 or more. When the silica concentration is 10 w / v% or more and less than 15 w / v%, the molar ratio n is preferably 8 or more. When the concentration is 1 w / v% or more and less than 10 w / v%, the molar ratio n is preferably 4 or more, and the mixture of the metal silicon silica sol and the silica compound should not precipitate during the injection time. The silica concentration of the metal silicon silica sol used at this time is expressed as w / w%, and the silica concentration of the silica solution after blending is expressed as w / v%.

As an example, the case where No. 3 water glass or high molar ratio water glass is used for the metal silicon silica sol in this invention is shown. The silica concentration was measured to be 20, 15, 10, 5 w / v%, and the molar ratio was 15, 10, 8, 6, 5 or 4 and mixed. The results when the high molar ratio water glass is mixed are shown in Table 5 below and the results when the No. 3 water glass is mixed are shown in Table 6 below. The white turbidity was determined to be white turbid by the absorbance meter at 660 nm with an absorbance of 0.1, and evaluated according to the following criteria.
○ Transparent: The mixture solution is transparent and no precipitation is observed. Δ White turbidity: Although it is cloudy, no separation or large amount of precipitation is observed within 24 hours.
X Separation and precipitation: Increase in viscosity / separation / a large amount of precipitation is observed within 24 hours immediately after compounding.

From the results of the above examples,
1. When silica sol produced from metallic silicon is used, strength is obtained in the long term in the vicinity of neutrality compared to silica compounds such as silica sol obtained by ion exchange treatment of water glass used in the past, and volume shrinkage is also small. I understood.
2. When silica sol produced from metallic silicon is used, the gel can be maintained at the same strength and suspension grout as conventional silica colloids, and a long gelation time can be obtained with a small amount of curing agent and acid. I was able to.
3. By further ion-exchanging the silica sol produced from metallic silicon to remove Na ₂ O, a long gelation time could be obtained even at neutrality.
4). By further ion-exchanging the silica sol produced from metallic silicon to remove Na ₂ O, it was possible to obtain a long gelation time with a smaller amount of curing agent and acid. Further, even when sulfuric acid is used as the acid, only a small amount is required, so that the influence of sulfate ions on the concrete is small.

  As described above, the ground injection material using the silica solution of the present invention has extremely excellent characteristics in terms of durability (durability), osmosis solidification, and environmental conservation even under high water pressure, and can be used in a wide range of applications. It was found that sex was obtained.

Claims (11)

A ground injection material containing a silica solution,
The silica solution contains silica sol produced from metallic silicon as an active ingredient, Na ₂ O is in the range of 0.1 w / w% to 4.0 w / w%, and the pH is 1 to 11, and The ground injection material characterized by having a silica concentration of 1 to 75 w / v%.   The ground injection material according to claim 1, wherein the silica solution contains, as an active ingredient, one or more selected from the group consisting of acids and salts in addition to the silica sol.   The ground injection material according to claim 1 or 2, wherein the silica solution contains water glass and an acid and / or salt as active ingredients.   The ground injection material according to any one of claims 1 to 3, wherein the acid is phosphoric acid. The ground injection material according to any one of claims 1 to 4 , wherein the silica solution has a pH of 4 to 9 by ion-exchange treatment of the silica solution. The ground injection material according to any one of claims 1 to 5 , comprising one or more selected from slag, a polyvalent metal compound, an alkali metal salt, an alkaline compound, a sequestering agent and an organic compound. . In the ground injection method of injecting the ground injection material according to any one of claims 1 to 6 , into the ground,
The ground injection method according to claim 1, wherein the groundwater in the ground contains one or more selected from the group consisting of seawater, calcium and magnesium. The ground injection material is injected into the ground below the groundwater level to form a water blocking layer to contain waste or soil contaminants, or to build cavities and tunnels for storing gas, liquid fuel and waste The ground injection construction method according to claim 7 . In the ground injection method of injecting the ground injection material according to any one of claims 1 to 6 , into the ground,
Before or after injecting the ground injection material into the ground, a ground injection material containing cement or slag as an active ingredient is injected into the ground. In the ground injection method of injecting the ground injection material according to any one of claims 1 to 6 , into the ground,
A ground pouring method characterized by pouring the ground pouring material into the ground under high water pressure. In the ground injection method of injecting the ground injection material according to any one of claims 1 to 6 , into the ground,
Injecting the ground injection material into the ground to improve the permanent ground or prevent liquefaction.