JP2009173924A - Grouting agent and grouting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grouting agent and a grouting method capable of providing high durability against high seepage pressure, in particular, in grouting for a rock bed having a crack, and capable of obtaining high permeability and a high water cut-off effect. <P>SOLUTION: This grouting agent of injecting a silica grout into the ground contains, as a main material, a compound silica colloid containing a silica colloid and a fine particular spherical silica in the silica grout. The ground is consolidated by injecting the grouting agent, and a strength is held over a long period, by this grouting method. Water cut-off performance and the strength are held over a long period under the seepage pressure in an underground, by injecting the grouting agent, in the grouting method. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a ground injecting agent and a ground injecting method, and more particularly, a ground injecting mainly composed of a composite silica colloid that has excellent durability against high osmotic water pressure and provides high permeability and water stopping effect. The agent and ground injection method. In particular, in the water stop around the cavity formed by rock breakage and rock excavation under high osmotic water pressure, the gel is excellent in the rock filling and the high osmotic water pressure works. The present invention is also related to a ground injection method capable of maintaining a long-term water-stopping property without extruding the gel, and the above-mentioned effects can be obtained.

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

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

  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 based on acidic silica sol, grout based on active silica obtained by treating water glass with a cation exchange resin or ion exchange membrane, and active silica are concentrated and granulated. And a weakly alkaline and stable silica colloid having a pH of 9 to 10 (Patent Documents 1 and 2).

  However, in the injection of sand ground or rock mass under high osmotic water pressure, in the above-mentioned solution type silica grout, the gel between the soil particles or silica gel in the crack of the rock mass is pushed out by water pressure after injection, and the water stopping And long-term durability is reduced. For this reason, cement-based suspension-type injections are used instead of solution-type silica grout, but suspension-type injections have large particle diameters, low water permeability, or rocks with fine cracks. It was unsuitable for. In particular, in the case of rock injection with cracks under high osmotic water pressure, the injected solution does not penetrate into the rock itself, but only fills in the cracks and gels, so gel shrinkage, breathing, and silica leaching. If there is, the water stop effect is insufficient and durability cannot be expected. In addition, when the viscosity is large, the particle size is large and the permeability is poor and only the large voids are filled, or when the consolidation distance is short, the gel strength is reduced or the gel shrinks when the gel shrinks. Will be pushed out.

Therefore, as a technique for improving such points, ultrafine particle cement is used, or as disclosed 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, Thereby, even if the solid ground by the said silica grout is under osmotic water pressure, the ground injection construction method which keeps water-stop and intensity | strength for a long term is disclosed by this applicant.
Japanese Patent No. 3205900 JP 2004-35584 A JP 2006-226014 A

  However, although the method described in Patent Document 3 can maintain water-stopping strength and strength over a long period of time, it is still not sufficient for high osmotic water pressure, and today it has better durability, permeability and There is a need for a water stop effect.

Therefore, the object of the present invention is to solve the above-mentioned problems in the prior art, and against high osmotic water pressure,
In particular, it is an object of the present invention to provide a ground injection agent and a ground injection construction method which have excellent durability and can provide high permeability and water stopping effect in rock injection with cracks.

  As a result of intensive studies to solve the above problems, the present inventor has found that the following requirements (1) and (2) are required to solve the above problems.

(1) The average particle size of ultra-particle cement is about 5 to 10 μm, and it is impossible to fill fine cracks in the rock. The water stoppage of rock cracks under high water pressure needs to have a smaller particle size.

(2) Silica colloid is usually in the particle size range of 6-50 nm and has excellent permeability, but when it alone is used, only the gel is filled in the cracks in the rock, and the gel strength is insufficient under high water pressure. It becomes. For this reason, there is a method in which ultrafine cement is mixed and injected into a silica colloid solution. In this case, the cement immediately reacts with the silica colloid, resulting in poor permeability. In addition, the ultrafine cement itself is brijinned or filtered on the crack surface and does not penetrate into the fine cracks. Therefore, in order to increase the strength in addition to the silica colloid, the particle size should be smaller than that of the fine particle cement, larger than that of the silica colloid, not reactive itself, and not react immediately with the silica colloid. Is preferred.

  By using a composite silica colloid containing silica with different average particle sizes and specific surface areas, it was found that it has excellent durability against high osmotic water pressure, and high permeability and water-stopping effect can be obtained. The invention has been completed.

  The present invention is a composite silica colloid obtained by adding fine particle spherical silica to a silica colloid, and the fine particle spherical silica has a particle size larger than that of the silica colloid, smaller than that of the ultrafine particle cement, and itself has reactivity. In addition, the silica colloid which is pure silica particles does not react immediately and has an effect as an aggregate of fine particles in addition to the silica colloid, and the silanol groups (—OH) of the silica colloid and each silica surface with time. ) Combining with each other, we found that large colloidal particles were grown and filled with small colloids between the large colloids, and the silanol groups reacted with each other to form a solid silica gel. Thus, the present invention has been completed.

  That is, the ground injecting agent of the present invention is a ground injecting agent for injecting silica grout into the ground, wherein the silica grout is mainly composed of a composite silica colloid containing silica colloid and fine-particle spherical silica. To do.

  Further, the ground injection method of the present invention is characterized in that the ground is consolidated by injecting the ground injection agent and has strength over a long period of time.

  Furthermore, another ground injection method of the present invention is characterized in that the ground injection agent is injected so that it has water-stopping and strength for a long time under osmotic water pressure in the underground.

  Furthermore, in another ground injection method of the present invention, the ground is mainly composed of a rock having cracks under hydraulic pressure, the ground injection agent is injected into the rock, the cracks are filled with gel, Even under, the gel is characterized by having a long-term water-stopping property without being extruded.

  Furthermore, in another ground injection method of the present invention, by injecting the ground injecting agent, a waste water is contained in the bedrock under infiltrated water, or a hollow water-stopping layer for storing gas or liquid fuel is formed. It is characterized by doing.

  INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a ground injecting agent and a ground injecting construction method that have excellent durability, and have high permeability and water stopping effect, particularly in rock infusion with cracks against high osmotic water pressure. It became.

Hereinafter, embodiments of the present invention will be specifically described.
The silica colloid used in the present invention is a colloid obtained by concentrating and increasing the active silica to make it weakly alkaline. Further, active silica colloid which is a polymer of active silica obtained by treating water glass or acidic water glass obtained by mixing water glass and acid with an ion exchange resin or an ion exchange membrane, and water glass on the active silica colloid. In addition, silica colloid obtained by adding acid or salt. The composite silica colloid which is the main material of the present invention contains fine particle spherical silica having an average particle diameter of 0.10 to 1.0 μm and a specific surface area of 5 to 40 m ² / g in the silica colloid. When fine spherical silica adjusted to be weakly acidic is used and colloidal silica is weakly alkaline, PH can be neutralized and gelled by mixing them. Further, the composite silica colloid used in the present invention may be a mixture of water glass, acid, salt, sequestering material and the like.

The fine particle spherical silica constituting the composite silica colloid used in the present invention is not particularly limited as long as a desired effect is obtained, but the average particle size is 0.10 to 1.0 μm and the specific surface area is 5 to 40 m ² / g. Preferably there is. Such fine-particle spherical silica is not limited as long as this condition is satisfied. For example, while siliceous raw material powder is injected into a high-temperature flame formed by a combustible gas and an auxiliary combustion gas, In the method of collecting the spherical silica powder, the dew point of the gas humidity from the furnace body to the collector is maintained at 30 to 75 ° C., thereby producing the spherical silica powder having the optimum silanol group concentration, and further classification treatment Thus, a fine spherical silica powder having an average particle diameter and a specific surface area excellent in fluidity promoting effect can be obtained by a method of collecting.

Further, such fine-particle spherical silica preferably has an average value of sphericity of 0.90 or more, particularly 0.95 or more. The sphericity can be measured using a scanning electron microscope (“JSM-T200 type” manufactured by JEOL Ltd.) and an image analyzer (manufactured by Nippon Avionics Co., Ltd.). For example, first, the projected area (A) and the perimeter (PM) of particles are measured from an SEM photograph of powder. When the area of a perfect circle corresponding to the perimeter (PM) is (B), the sphericity of the particle can be displayed as A / B. Therefore, assuming a perfect circle having the same circumference as the sample particle (PM), PM = 2πr and B = πr ² , so that B = π × (PM / 2π) ² , and each particle Can be calculated as sphericity = A / B = A × 4π / (PM) ² , and therefore an average value of 200 arbitrary particles can be obtained as the sphericity of the powder.

  Furthermore, the amorphization rate of the fine-particle spherical silica is preferably 95% or more, particularly 98% or more. The amorphization rate is determined by performing X-ray diffraction analysis of a sample using a powder X-ray diffractometer (for example, “Mini Flex” manufactured by RIGAKU) in the range of 2θ of CuKα ray of 26 ° to 27.5 °, It can be measured from the intensity ratio of the specific diffraction peak.

Furthermore, the silanol group concentration of the fine spherical silica is preferably 0.5 to 5.0 / nm ² . The silanol group concentration can be measured by the Karl Fischer method.

  Examples of the fine particle spherical silica include SFP-30M manufactured by Denki Kagaku Kogyo Co., Ltd.

  The ground injecting agent containing the composite silica colloid of the present invention as a main material preferably contains 1 to 50% by mass of the silica colloid, and contains 1 to 50% by mass of fine-particle spherical silica, thereby preventing high osmotic water pressure. The desired effects of the present invention such as excellent durability can be obtained satisfactorily. Currently, silica colloids with a concentration of 30 to 50% are used for ground injection, and at higher concentrations, colloids adsorb and partially gel, making it impossible to obtain a uniform gel. . Moreover, when the addition amount of the fine particle spherical silica is more than 50% by mass in the ground injection agent, the viscosity becomes high and the penetration becomes difficult.

  Moreover, the ground injection agent of this invention can also contain 1-20 mass% of water glass further. Water glass contains many silanol groups and has high reactivity, so that the initial strength development is fast. However, since it contains more Na than colloidal silica and gelation occurs after gelation, it is necessary to keep the above amount.

  When water glass is added, water glass and acid are mixed and added as acidic water glass, or by forming an acidic composite silica colloid containing water glass and acid, a small colloid of 1 nm or less of acidic water glass is added. Composite silica colloids are 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 a composite silica colloid 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-mentioned composite silica colloid according to the present invention has high reactivity, and even when injected into the ground into which a suspension of fine particles exhibiting alkalinity is injected, it is not easily affected by alkalinity and is large under high water pressure. 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.

  The silica colloid in the present invention is obtained by removing most of alkali metal ions from a liquid alkali metal silica salt aqueous solution (water glass). For example, a zeolite cation exchanger, an ammonium ion exchange It is obtained by passing water glass through the body ion exchange resin, adding the generated silica colloid to the water glass at a temperature of 80 ° C. to 90 ° C., and passing again through the ion exchange resin for ion exchange. A relatively pure (dilute) silica colloid (active silica colloid) is obtained.

  Furthermore, in order to obtain a pure silica colloid, the above-mentioned dilute silica colloid is prepared to be slightly alkaline, and the silica colloid is further added to the above-mentioned silica colloid to evaporate to stabilize and concentrate simultaneously, or after ion exchange. A method is used in which the active silica colloid is heated under an appropriate alkali, and the active silica colloid is further added thereto for stabilization.

Since the colloidal silica solution in the present invention is almost completely free of Na ions, it usually exhibits weak alkalinity with a pH of 10 or less, and Na ₂ O is in the range of 0.2% to 4%. When Na ₂ O becomes 4% or more, the silica colloid dissolves and becomes an aqueous solution of silicate. On the other hand, when the Na ₂ O content is 0.2% or less, the silica colloid cannot exist stably and aggregates. That is, when Na ₂ O is in the range of 0.2% to 4%, Na ions can be distributed on the surface of the silica colloid and kept in a stable colloidal state.

  The silica colloid prepared in this way is almost neutral and semi-permanently stable, and when it 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. Even if this colloidal solution of silica is poured into the ground as it is, it does not gel within a practical time itself, so a practical consolidation effect cannot be obtained.

However, a monovalent alkali metal salt such as acid, NaCl or KCl, a polyvalent metal salt such as Al, Ca or Mg, or a hydroxide thereof is added to the composite silica colloid solution obtained by adding the ultrafine spherical silica to the silica colloid. When a gel material such as salt or other salt is added and injected into the ground as a mixture, the colloidal silica solution of the composite silica of the present invention combines the colloidal particles destabilized by the gel material in the ground, Form a solid consolidated body to consolidate the ground. Further, active silica or water glass may be added to the silica colloid, and phosphoric acid, sulfuric acid, other acids and salts, and sequestering agents may be added. In the present invention, the composite silica colloid 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 groundwater include Ca ²⁺ , Mg ²⁺ and iron ions. Metal ion sequestering agents such as phosphoric acid and phosphate compounds, chelating agents, etc. mask metal ions in the ground together with silica. It is presumed that a coating film is formed by the action and reacts with calcium and magnesium components such as trace metals in groundwater and shells to form insoluble or hardly soluble compounds. For this reason, an effect is obtained in which the penetration of the composite silica colloid is not inhibited by Ca and Mg in the ground.

  Furthermore, in the present invention, the sequestering agent is excellent in phosphoric acid compounds such as phosphoric acid and sodium hexametaphosphate, but other sequestering agents other than phosphoric acid compounds are used to mask the metal ions. It can also be expected. Such sequestering agents include tetrapolyphosphates, hexametaphosphates (especially sodium salts are good), tripolyphosphates, pyrophosphates, acidic hexametaphosphates, acidic pyrophosphates and other condensed phosphates, ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid, gluconic acid, tartaric acid or their salts.

  In the present invention, it is possible to inject into the ground using a combination of a ground injection containing the above-described silica colloid as an active ingredient and a suspension type injection. Examples of the suspension type injection include an injection containing fine particle cement, fine particle slag, or a mixture thereof as an active ingredient. By injecting these suspensions into the ground in advance and filling the rough cracks, even under osmotic water pressure in the underground, the water stoppage and strength can be maintained for a long time, and the ground can be improved. it can.

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

  The ground injection method of the present invention is characterized by using the above-mentioned ground injection agent in the ground injection method for consolidating the ground.

  In general, deep underground development does not require land acquisition costs, and furthermore, because it has great economic and planning advantages that it can be developed without being affected by existing structures, various structures utilizing shield technology Development is expected. Especially for long-distance and multi-directional lifelines, a deep underground underground of 40m to 100m is considered optimal, and for the time being, construction of lifelines for electric power and gas is expected to take precedence. .

  In addition, it is possible to excavate a deep pit with a depth of several hundreds to 1000 meters to form a large cavity, in which radioactive waste is enclosed, or LPG can be stored. In this case, it is possible to form a water-stopping layer that can withstand the high water pressure, and to maintain the strength and water-stopping ability to hold the cavity.

  Further, tunnel excavation in submarine tunnels and volcanic deposits may involve excavation work under pressurized water corresponding to a water pressure of 100 m to 200 m. These do not only take a long time for excavation work, but are also under high water pressure after completion of construction, and high osmotic pressure water may leak into 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 agent and ground injection method of the present invention are used for such applications.

  EXAMPLES Hereinafter, although this invention is described by an Example, this invention is not limited to these Examples.

(Experiment-1)
In order to confirm the effect of the present invention on the long-term durability of strength and consolidated strength under osmotic water pressure, the strength change of the composite silica colloid of the present invention cured under osmotic water pressure was observed as an example.

Materials used 1. Sand 6 and 7 mixed silica sand is used. The density (ρs) of sand is 2.667 g / cm ²
2. Injection agent: The following Table 1 (formulation per 1000 L of injection solution) was used.

3. Injection specimen Internal diameter 5cm x Height 10cm Using clear acrylic mold

Experimental Method Silica colloid containing 30% by mass of colloidal silica is reacted with fine spherical silica, water glass and potassium chloride, and sand is poured into a transparent acrylic cylindrical mold so that the density of sand is 1.5 g / cm ^3. It was produced by the method.

  Thereafter, room curing at 20 ° C. was performed for 2 days. After curing, the specimen was removed from the acrylic mold and placed in the center of the mold capable of osmotic water curing, and bentonite was packed around it so that there were no gaps or cavities. As a result, the permeated water from other than the specimen was completely blocked. After assembling the mold, it was installed in the curing water tank shown in FIGS. This water tank was adapted to be subjected to osmotic water pressure, and the osmotic water pressure was applied from below the injection specimen. The water pressure was adjusted so that the dynamic water gradient was 10. In addition, specimens prepared in the same manner were cured and compared under hydrostatic pressure.

  Further, from another experiment, it was found that the acceleration rate of the curing strength at 55 ° C. and 65 ° C. was about 30 times and about 50 times the standard curing temperature of 20 ° C. Therefore, the accelerated curing was performed. There were three curing temperatures of 20 ° C, 55 ° C, and 65 ° C.

  Changes in strength were measured for specimens cured under hydrostatic pressure and those subjected to hydrostatic gradient 10 in water for a long term. The results are shown in FIGS.

From this, it can be seen that those containing fine spherical silica (Examples 1, 2 and 3) have higher strength than those containing no fine spherical silica (Comparative Examples 1 and 2). It was also found that the same increase in strength as in the hydrostatic pressure state can be obtained without being affected by the osmotic water pressure for a long time. In Comparative Example 2, the hydrostatic curing showed 0.5 MN / cm ² , and thereafter there was no increase in strength. From this measured value, when the injection improvement range is 10 m, the strength develops at least 30 days in the state where the water head (H) of 100 m acts, and thereafter the same strength increase as the hydrostatic pressure state is not affected by the osmotic water pressure. I was able to guess.

(Experiment-2)
The volume change of Example 1 of Experiment-1 was measured. The volume change test of the homogel was carried out by the volumetric flask method. Place 100 mL of the injection into a 200 mL volumetric flask with a stopper, and let stand for 24 hours to gel. Ion-exchanged water was added up to the marked line and cured at room temperature 20 ° C. The gel volume was measured at 0, 7, 14, and 28 days after curing, and changes were observed. The volume change rate (%) of the homogel was calculated by the following formula.

  The results are shown in FIG. From this, it is considered that the blending of Example 1 does not cause water to flow due to shrinkage in the cracks, since the gel does not shrink or expand.

(Experiment-3)
Using a steel pipe having a length of 50 cm simulating a rock fracture shown in FIG. 6, the resistance of the injectant to water pressure was measured. The hole diameter of the pipe was set to 1, 3, 5 mm, and the injection agent 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 2.

  From this, the following was found. In Examples 1 to 3 of the composition shown in Table 1, resistance to water was exhibited in each of 1, 3, and 5 mm, and water was stopped. On the other hand, in Comparative Example 1, resistance was exhibited at 1 and 3 mm, but water was passed at 5 mm. In Comparative Example 2, all water was passed. In Comparative Example 2, it seems that the shrinkage occurred and a gap was formed between the steel plate and the water passed. From the above, it was found that the composite silica colloid containing ultrafine spherical silica was excellent in resistance to water pressure.

  There is a "water-sealed underground bedrock tank system" that contains oil and LP gas in a rock cavity dug underground. In the water-sealed underground bedrock tank system, the bedrock tank is located deeper than the groundwater level, and the pressure of the surrounding groundwater is always kept higher than the pressure of crude oil and LP gas in the tank. At this time, the injection of the present invention is injected into the ground around the tank and cracks in the ground, and solidified, so that the water can be stopped in the tank from the long-term strength and water stoppage by the ground injection of the present invention. , Can contain crude oil and gas.

It is a figure which shows a curing water tank. It is a figure which shows the cross section of a curing water tank. It is a figure which shows the intensity | strength change under a hydrostatic pressure. It is a figure which shows the intensity | strength change under osmotic water pressure. It is a figure which shows the volume change of a homogel. It is a figure which shows the steel pipe apparatus which simulated the crack of the bedrock.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steel pipe 2 Water pressure 11 Curing tank 12 Surface water 13 Mold 14 Water heater 15 Sample 16 Water pressure 21 Upper lid 22 Gravel 23 Bentonite 24 Rubber 25 Injection test 26 Wire mesh 27 Lower lid

Claims (9)

  A ground injecting agent for injecting silica grout into the ground, wherein the silica grout is mainly composed of a composite silica colloid containing silica colloid and fine spherical silica. The ground injection agent according to claim 1, wherein the fine-particle spherical silica has an average particle size of 0.1 to 1.0 µm, a specific surface area of 5 to 40 m ² / g, and 1 to 50% by mass.   The ground injection agent according to claim 1 or 2, wherein the silica colloid contains 1 to 50 mass% of colloidal silica having a particle diameter of 6 to 50 nm.   The ground injection agent according to any one of claims 1 to 3, comprising 1 to 20% by mass of water glass.   The ground injection agent as described in any one of Claims 1-4 containing 1 or more types selected from the group which consists of a salt, an acid, and a sequestering agent.   A ground injecting method characterized in that the ground is consolidated by injecting the ground injecting agent according to any one of claims 1 to 5 and has strength over a long period of time.   A ground injection construction method characterized by having a water stoppage and strength for a long time under osmotic water pressure in the underground by injecting the ground injection agent according to any one of claims 1 to 5.   A ground injection agent according to any one of claims 1 to 5 is injected into the ground, wherein the ground is mainly a rock having cracks under hydraulic pressure, and the crack is filled with gel, However, the ground injection method is characterized by having a long-term water-stopping property without extruding the gel.   By injecting the ground injecting agent according to any one of claims 1 to 5, the waste is contained in the rock in the infiltrated water, or a hollow water-stopping layer for storing gas or liquid fuel is formed. This is a ground injection method.