JP2855158B2 - Ground improvement material and its application - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a ground improvement material used for construction of a water blocking wall in the ground, reinforcement of the ground by injection, filling of voids in civil engineering and building structures, and ground excavated and formed in the ground near the retaining wall. Displacement absorbing ground structure with improvement material filling groove, backfilling method filled with soil improvement material with good waterproofness and no outflow, and method of preventing uneven settlement of structures on the ground by filling the ground improvement material with ground About.

2. Description of the Related Art

If the ground undergoes large deformation due to vibrations, changes in the temperature, etc., cracks will occur, which may result in a loss of water stoppage, ground movement, or the like, resulting in disasters. Therefore, as a countermeasure against these problems, a chemical liquid injection method, a filler filling method, and the like have been proposed. First, in the chemical injection method, in order to construct a water-stop structure by injecting water glass, acrylamide, urea, or other chemicals, the injection pitch is shortened due to the gel time of the chemical, and injection is performed at many locations. Otherwise, a water-stop construction with excellent continuity cannot be constructed, the workability is troublesome, the handling of chemicals requires attention, there are pollution problems, and the cost is high due to expensive chemicals. There is. For example, since a water glass-based injectant gels due to a chemical reaction, gel time, solidification strength, and the like are affected by the quality of groundwater and the mixing state of chemicals, and the injectable effect as prescribed may not be obtained. Was. Also, in the filler filling method, it is difficult to fill the filler such as clay, fly ash, etc.
Further, since the filled material has no strength, the ground may be deformed again after the filling, and there is a risk that cracks may occur. In addition, in the filling method using concrete or mortar, since the material is not flexible, when a large deformation occurs in the ground, the filling portion cannot be deformed (because the filling portion has no flexibility). In addition, there is a problem that a crack is generated in the portion when added to the deformation factor. In addition, embankment may be laid on the ground or chemical ground improvement may be performed in order to increase the bearing capacity of the ground. In such a case, the load at the time of construction generates pressure on the side, displacing the ground to the side, and may affect surrounding structures. In order to absorb such lateral displacement, a flexible underground structure for absorbing the displacement may be constructed in advance. For example, muddy water or still water is put in the groove, or a special rubber bag containing a stabilizing liquid is put in the groove. However, in the above method, there is a risk that the trench itself may collapse due to ground displacement, and there will be a problem with the passage of heavy construction equipment, etc. It is difficult to determine the shape of the displacement absorption groove, and the versatility is poor. Further, voids formed on the back of the parent pile horizontal sheet pile or on the back of a shield such as a tunnel have been filled with sandy soil, cement paste, or an in-situ soil mixture. However, sandy soil backfilling material filled on the back of the parent pile horizontal sheet pile often runs off after backfilling, and backfilling with cement paste or in situ soil is poor in continuity and often leads to water leakage. Was. In addition, when installing a structure in the ground subsidence zone, many piles are driven into the ground until it reaches the deep solid ground, and it is built to support the structure on it,
Subsequent subsidence of the ground causes voids in the state where only the piles are exposed between the lower surface of the building and the ground surface. Since this exposed pile is in an exposed state and its outer periphery is not supported by the ground or the like, it becomes weak to a lateral force, that is, a horizontal force, and there is a danger that the structure will collapse due to a rolling earthquake or the like and collapse. . However, heretofore, there has been no effective method of reinforcing this pile. On the other hand, the structure installed on the soft ground surface has a partially different weight, that is, because of uneven load,
Some parts of the construct have more subsidence than others,
The structure may settle with a slope. Further, even when the load distribution of the building is uniform and the ground of the supporting layer is horizontal, a large subsidence occurs at the center of the mounting ground in the plane compared to the end face. As a countermeasure against such settlement, usually, a large number of support piles are driven in. However, when the support layer ground is deep, a large number of long piles are required, which increases the cost.

[Means for Solving the Problems]

In view of the problems of the prior art described above, the present inventors have conducted intensive studies and found that the ground of the present invention is capable of constructing a well-filled, excellent water-blocking, flexible, and pollution-free water-blocking section. Improved materials have been developed. In addition, a displacement ground structure which is filled with a displacement absorbing material made of the above ground improvement material having a good filling property and an excellent displacement absorbing property was developed. In addition, a backfilling method was developed in which a ground improvement material having good water stopping properties and capable of completely preventing the backfilling material such as sand from flowing out was filled. In addition, a method was developed to easily prevent uneven settlement of structures on the ground. That is, the present invention is a ground improvement material characterized by adding and mixing fibers to an aqueous solution of a hydrophilic material such as agar, gelatin, which melts and solidifies due to a temperature change in a temperature range from room temperature to about 100 ° C., A soil improvement material characterized by adding and mixing soil, bentonite, sand, etc. to the same material, and the material is suspended on a ground near a ground wall such as a soil retaining wall, a mountain retaining wall, an underground wall, etc. A displacement absorbing ground structure characterized by being filled in a displacement absorbing groove, a backfilling method characterized by filling the same material into a sheet pile back gap, a shield wall back gap, etc., and a ground filling method using the same material. This is a method for preventing uneven settlement of structures on the ground by filling the inside. In the ground improvement material of the present invention, it is preferable to add and mix fibers and an inorganic material fine powder such as soil, clay and bentonite to the aqueous solution of the hydrophilic material from the viewpoint of increasing strength, adjusting specific gravity, and the like. It is also preferable to add and mix an organic paste such as alpha starch, CMC, protein, etc., because it helps to improve the strength. Furthermore, it is also preferable to add a preservative in that it can prevent the above soil improvement material from being corroded and deteriorated by bacteria. The hydrophilic material in the ground improvement material of the present invention melts and solidifies due to a temperature change in a temperature range from room temperature to about 100 ° C. However, heating to a temperature of about 100 ° C is a boiling point. This is because it can be carried out easily by water, hot air or the like and without any particular danger in the work. The unit weight of the hydrophilic material is usually 1.0 to 1.3 t / m ³ . When the hydrophilic material is agar, an aqueous solution of 0.2 to 4% is preferable. In this case, the melting temperature (the temperature at which a gel state changes to a sol state) is 80 to 90 ° C., and the solidification temperature (the sol state changes to a gel state). Temperature) is 30-40 ° C. Such agar ground improvement material has a water permeability of 1 × 10 ⁻⁶ to 1 × 10 ⁻⁸ cm / sec when it solidifies due to a decrease in temperature. As another hydrophilic material, there is, for example, gelatin, and an aqueous solution thereof undergoes gel-sol conversion due to a change in temperature, so that it can be used for the ground improvement material of the present invention similarly to the agar aqueous solution, but deterioration due to decay occurs. Agar is preferred because of its ease. Since the soil improvement material of the present invention changes its form due to temperature change, that is, changes its sol-gel form, it can be injected into the ground to form an improved ground. Has a small deformation coefficient,
Also, since the strain leading to destruction is large, even if a large deformation due to an earthquake or the like acts on it from the surroundings, it easily follows, so cracks like the water stop part by the injection of the chemical solution or the filling of the filler in the conventional technology. No problems arise. FIG. 1 shows the results of a uniaxial compression test of agar gel (agar agar solution of 1 to 4%).
It turns out that it is rich in flexibility. Further, the ground improvement material of the present invention has good permeability in a sol state in a heated state, so that the ground filling material in a heated state is extremely good and easy. Therefore, when the ground or the aqueous solution of the hydrophilic material is heated at the time of filling, good filling properties are ensured, but a method of preheating the ground is particularly preferable. As a method of heating the ground, hot air is applied to the hole dug in the ground,
A method of supplying hot water, a method of inserting an electric heater to heat the electric current, and the like can be adopted. The ground improvement material of the present invention causes clogging,
For the purpose of obtaining higher strength, for example, pastes such as CMC and PVA, short fibers, water-insoluble inorganic fine powder such as bentonite, and organic fine powder such as polymethacrylate resin can be added. The soil improvement material of the present invention has a unit volume weight of about 1.0 ton / m ^{3 in} the case of an aqueous agar solution, which is lighter than that of ordinary soil. An inorganic fine powder such as ash or silica sand powder can be added and mixed to obtain a specific gravity as appropriate. The strength of the coagulated product (agar gel) of the aqueous solution of the hydrophilic material which is the base material of the soil improvement material of the present invention can be adjusted by changing the concentration of agar as shown in FIG. Further, as shown in FIG. 3, the strength can be approximately doubled only by adding, for example, 0.2% of CMC. Further, the ground improvement material of the present invention has a higher water stopping property than sand, general ground, and the like. For example, the solidified agar aqueous solution as a base material is about 1 × 10 ⁻⁶ to 1 × 10 ⁻⁸ cm / sec. And has sufficient performance as a water stop wall.

【Example】

Next, the present invention will be specifically described with reference to examples. First Example; (Example 1 of ground improvement material) (1) First, agar having a weight ratio of 1% is dispersed in water and heated to 85 ° C. to prepare an agar aqueous solution. (2) Next, a small amount of short fibers and carboxymethylcellulose (CMC) are added and dissolved in the agar aqueous solution in a small amount of 0.2%.
This may be done by adding an aqueous solution in which the required amount of CMC is dissolved to the agar solution. (3) Thereafter, the solution is transferred to an injection pump while maintaining the temperature of the aqueous solution of agar of the above (2) at a solidification point (30 to 40 ° C.) or higher, and then pressed into the ground. (4) Therefore, utilizing the fact that the temperature of the ground is about 15 ° C., the injected agar aqueous solution is naturally cooled and solidified to construct a water blocking wall. (5) By repeating the above steps (3) and (4), a continuous water stop wall can be constructed in the ground. Second Example: (Example 2 of ground improvement material) (1) First, agar having a weight ratio of 1% is dispersed in water and heated to prepare an agar aqueous solution. (2) A small amount of short fibers and 20 to 30% of sand are added to the aqueous agar solution, and the mixture is gradually cooled. When the temperature approaches the freezing point, the whole solution is stirred to suspend and suspend the sand. (3) While maintaining the temperature of the agar aqueous solution-sand slurry at a constant value (about 40 ° C.), the slurry is transferred to a pre-constructed ground excavation hole by a pressure pump and poured. (In this case, if the temperature is too high, the viscosity of the agar liquid will be too low and the sand will settle and separate, so it is necessary to lower the temperature until a suitable viscosity is obtained. This temperature depends on the particle size of the sand, the type of agar, etc. (4) By utilizing the fact that the temperature of the ground is about 15 ° C., the slurry is naturally cooled and solidified to construct a water blocking wall. (5) A continuous water blocking wall is constructed by repeatedly performing the steps (3) and (4). Example 3: (Example 3 of ground improvement material) First, (1) agar having a weight ratio of 1% is dispersed in water and heated to prepare an agar aqueous solution. (2) Add a small amount of short fibers and bentonite to the aqueous agar solution.
% To give an aqueous agar-bentonite slurry. (3) The slurry is transferred to an injection pump while maintaining the slurry temperature at or above the freezing point (30 to 40 ° C.), and then pressed into the ground. (4) By utilizing the fact that the temperature of the ground is about 15 ° C., the slurry is naturally cooled and solidified to construct a water blocking wall. (5) By repeating (3) and (4), a continuous water stop wall is constructed in the ground. Fourth Embodiment (Example of Ground Absorbing Structure) This example is an example in which a displacement absorbing ground structure is constructed. (1) First, as shown in the sectional view of FIG. 4 (a), the ground 1 is excavated, and then the underground wall 2 is provided on the excavated surface.
The trench 3 is excavated near it and erected. (2) Next, agar at a weight ratio of 1% is dispersed in water and heated to 85 ° C. to prepare an agar aqueous solution, and a small amount of short fibers and carboxymethyl cellulose (CMC) are further added to the agar aqueous solution.
Dissolve by adding 0.2% to prepare a displacement absorbing material aqueous solution. This may be done by adding an aqueous solution in which the required amount of CMC is dissolved to the agar solution. (3) Thereafter, the displacement absorbing material aqueous solution obtained in (2) is transferred to an injection pump while maintaining the temperature of the aqueous solution of the displacement absorbing material at a solidification point (30 to 40 ° C.) or higher, and then injected into the ground groove 3. (4) Therefore, utilizing the fact that the ground temperature in the vicinity of the ground groove 3 is about 15 ° C., the injected aqueous solution is naturally cooled and solidified to form the displacement absorber 4, and the displacement absorbing ground structure of this embodiment is used. To form (5) By repeating the steps (3) and (4), a continuous displacement absorbing ground structure can be constructed in the ground wall. Needless to say, the displacement absorbing material may be a mixture of sand prepared in Examples 2 and 3 or a mixture of bentonite. The operation and effect of the displacement absorber 4 of this embodiment are as follows. For example, when the packed hit the Sunakui 5 on the right side of the ground wall 2 of 4 (a), as in the FIG. 5 (b), subjected to any pressing force f ₁ from the side to the ground wall 2, ground wall 2 'is deformed, even if applied pressing force f _2, were deformed displacement absorbing member 4 further displacement absorber 4' becomes. However, the pressing force from the side due to the compaction of the sand pile 5 is all absorbed by the displacement absorber 4 ', and as a result, any displacement is applied to the ground on the left side of the sand pile 5 (for example, the neighboring ground). Never. Example 5: (Example 1 of backfill method) This example is an example of the backfill method using the above ground improvement material as the backfill material. As shown in the cross-sectional view of FIG. 5, the ground 1 is excavated, and a plurality of parent piles 6...
・ ・ Insert the horizontal sheet pile 7 ・ ・ from above. After that, the ground improvement material 8 of the agar substrate was
And the gap 9 between the ground and the ground 1 is filled. (1) First, agar at a weight ratio of 1% is dispersed in water and heated to 85 ° C. to prepare an agar aqueous solution, and a small amount of short fibers and carboxymethyl cellulose (CMC) are further added to the agar aqueous solution.
Add 0.2% and dissolve to prepare and prepare an aqueous solution of soil improvement material. This may be prepared by adding an aqueous solution in which the required amount of CMC is dissolved to the agar solution. (2) Thereafter, the aqueous solution of the soil improvement material is transferred to an injection pump while maintaining the temperature of the aqueous solution for soil improvement at a solidification point (30 to 40 ° C.) or higher, and then injected into the gap 9. (4) Then, utilizing the fact that the ground temperature near the gap 9 is about 15 ° C., the injected aqueous solution is naturally cooled and solidified to form the water-stopping backing material layer 8 ′. (5) By repeating the steps (3) and (4), a continuous backfill material layer 8 'can be formed along the back surface of the horizontal sheet pile 7. Needless to say, the ground improvement material 7 may be a mixture of sand prepared in Examples 2 and 3 or a mixture of bentonite. When the ground improvement material 8 is filled, the filling pipe is pulled up and down in the gap 9 while moving back and forth and right and left, so that the water-impermeable backing material layer 8 ′ is mixed with the in-situ soil 1. It is also preferred to form Example 6 (Example 2 of backfilling method) This example is an example of backfilling in the shield method, as shown in a schematic sectional view of FIG. After the construction, the ground improvement material 7 is filled in the gap 9 'on the upper rear surface of the shield wall 10. As the ground improvement material, a high strength material obtained by adding sand to an agar aqueous solution and mixing was used. This high ground improvement material supports the earth pressure so that the ground 1 from above does not collapse. Example 7 (Example 3 of backfilling method) This example shows a schematic cross-sectional view of FIG.
The structure 11 is mounted on a concrete pile 12 planted on a solid support layer ground 13. As the ground 1 subsided, a gap 9 ″ was formed between the structure 11 and the ground 1. The gap 11 was filled with a high-grade soil improvement material 7 including sand and surrounded the exposed portion of the concrete pile 12. This prevents the exposed portion of the concrete pile 12 from being broken due to horizontal vibrations, etc. Example 8: (Example 1 of uneven settlement prevention method) This example is shown in FIG. As shown in the figure, first, the middle part of the solid support layer ground 13 is filled with the anti-sinking material layer 14 made of the ground improvement material of the present invention, and the concrete pile 12 is planted thereon, and then the structure Install 11. Even if partial uneven settlement occurs in the ground 1, since the ground improvement material 7 of the present invention has flexibility, the partial uneven settlement is absorbed, and as a result, the structure 11 is unevenly deformed. In this example, the ground improvement material was sand or the like. Example 9: (Example 2 of the method of preventing uneven settlement) In this example, as shown in a schematic cross-sectional view of FIG. Part is filled with the anti-sinking material layer 14 made of the ground improvement material of the present invention, and a number of pile-like bodies 12 ′ made of the ground improvement material of the present invention are filled thereon and filled and implanted. The object 11 is set up.The pile-like body 12 'is made of a sandy pile using a sandy soil improvement material, and the present invention is applied to the case where partial uneven settlement occurs in the ground 1. Since the ground improvement material 7 has flexibility, it absorbs partial uneven settlement, and as a result, the structure 11 does not settle unevenly. Example 10: (Prevention of differential settlement) Example 3) The structure on the ground deforms or tilts with uneven settlement of the ground due to uneven weight of the ground (uneven distribution of load), inclination of the supporting ground, etc. As shown in a schematic sectional view of FIG. 10, the load of the structure 11 on the ground 1 is supposed to be uniform and the support layer is horizontal. In FIG. 10, the center of the plane of the structure has a larger settlement than the end, resulting in uneven settlement.In FIG. 10, the structure 11 initially has the shape indicated by the dotted line. In this case, an irregular settlement state deformed into the shape of the curved experimental instruction state, that is, of the maximum settlement G, G ′ is an irregular settlement in the center portion. 16 Take various measures as shown in the figure. Example of FIG. 11 In this example, a solid anti-settling material layer 15 made of the soil improvement material of the present invention is filled on a solid support layer ground 13 to form a hemisphere, and the sphere is formed in the center of the spherical surface. Formed in contact with the solid ground 13 surface, and the structure 11
Is installed. With such an arrangement, uneven settlement of the structure 11 can be prevented. Also in this example, it is preferable to form the uneven settlement material layer 15 by using a ground improvement material having a lot of sand. Example of FIG. 12 This example is the same as the example of FIG. 11, except that the hemispherical anti-settlement material layer is reversed and is covered on the solid ground 13 surface.
15 'is provided, and the operation and effect are the same as those in the example of FIG. Example of FIG. 13 In this example, the sand pile-like body 16 made of the soil improvement material 7 is fixed to the solid ground 13 in accordance with the load distribution state of the structure 11 of FIG.
Above, it is formed higher in the center and lower toward the end. Instead of the sand pile-like body 16, the ground improvement material may be formed in a ring shape, and a high ring-shaped body may be formed at the center and a low ring-shaped body may be formed at the end. Example of FIG. 14 In this example, a sand pile-like body 16 made of the ground improvement material 7 is fixed to the solid ground 13 in accordance with the load distribution state of the structure 11 of FIG.
The anti-sinking material layer 15 'having a hemispherical shape is placed thereon. Also in this case, instead of the sand pile-like body 16, the ground improvement material may be formed in a ring shape, and a high ring-shaped body may be formed at the center and a low ring-shaped body may be formed at the end. Example of FIG. 15 In this example, all the loads of the structure 11 are supported by a large number of sand pile-like bodies 16 made of the ground improvement material 7 to cope with uneven settlement. Example of FIG. 16 In this example, a sand pile-like body 16 made of the ground improvement material 7 is fixed to the solid ground 13 in accordance with the load distribution state of the structure 11 of FIG.
Above, arrange with the center part lower and the ends higher.
A hemispherical non-uniform settlement preventing material layer 15 is placed thereon, and the structure 11 is placed thereon. Also in this case, instead of the sand pile-like body 16, the ground improvement material may be formed in a ring shape, and a low ring-shaped body may be formed at the center and a high ring-shaped body may be formed at the end. Example of FIG. 17 In this example, the solid support ground is inclined in the ground as shown in the figure, and the distance to the solid ground 13 is long on the left side of the drawing and short on the right side. Therefore, the uneven settlement preventing material layer is formed as a deformed spherical body 15 ″ that is higher on the left and lower on the right to correspond to the load distribution.

【The invention's effect】

The present invention is as described above. (1) The ground improvement material of the present invention has an extremely good filling property into the ground, and after being heated and filled, is left to stand naturally, so that it becomes more flexible due to a temperature drop. It results in certain high strength solids. Therefore, it is possible to form a ground that is flexible and has excellent water stopping properties. The material is non-polluting and does not impair the natural environment for animal and plant propagation. The ground improvement material of the present invention is effectively used for construction of a ground suspension water wall, construction of backfill, and the like. (2) The material relating to the displacement absorbing structure of the present invention can be easily filled into the ground groove, and becomes a flexible solid displacement absorber due to a temperature drop by being left naturally after heating and filling. . Therefore, it is possible to form an excellent displacement absorbing ground structure that is flexible and can sufficiently achieve displacement absorption, and lateral pressure is applied from the deep ground to the ground wall due to factors such as nearby ground construction and earthquake. However, the ground wall is not displaced or deformed. As a result, the risk of road disasters and basement wall destruction due to ground wall collapse can be significantly reduced. (3) According to the backfilling method of the present invention, since the backfilling material made of the above ground improvement material has a good filling property and an excellent water stopping property, the ground near the backfilling portion collapses by an easy operation. This can be prevented. (4) According to the uneven settlement prevention method of the present invention, the ground is filled with the uneven settlement preventive material made of the ground improvement material of the present invention in various forms, that is, the load distribution of the structure on the ground and the ground By filling and forming the uneven settlement material layer corresponding to the load distribution, the uneven settlement of the structure can be easily prevented.

[Brief description of the drawings]

FIG. 1 is a club diagram showing the results of a uniaxial compression test of agar gel (agar aqueous solution of 1 to 4%), FIG. 2 is a graph showing the relationship between the shear strength of agar gel and the concentration of agar, and FIG. FIG. 2 is a diagram showing the relationship between the types and amounts of additives and the shear strength of agar gel. FIG. 4 (a) is a schematic cross-sectional view of the displacement absorbing ground structure according to the embodiment of the present invention, FIG.
Fig. 5 is a schematic cross-sectional perspective view of the backfilling method on the back of the horizontal sheet pile, Fig. 6 is a schematic cross-sectional view of the backfilling method on the back of the shield wall, and Fig. 7 is between the structure on the concrete pile and the ground. Figure 8 is a schematic view of filling the gap created with the backfill material by this backfill method, FIG. 8 and FIG. 9 are schematic cross-sectional views of the method for preventing uneven settlement of various structures, and FIG. Explanatory diagram of load distribution, Fig. 11 to Fig. 16 are schematic cross-sectional views of methods for preventing uneven settlement of various structures, and Fig. 17 is an outline of methods for preventing uneven settlement of structures when the solid ground is inclined. The sectional views are respectively shown. 1: ground, 2, 2 ': ground wall, 3: groove, 4, 4': displacement absorber, 5: sand pile, 6: parent pile, 7: horizontal sheet pile, 8: ground improvement material, 8 ': back Filling material layer, 9, 9 ', 9 ": gap, 10: shield wall, 11: structure, 12: concrete pile, 12': pile-like body, 13, 13 ': ground of support layer, 14: prevention of settlement Material layer, 15, 15 ', 15 ": Differential settlement prevention material layer, 16 ...: Differential settlement prevention pile-like body

Continuation of front page (72) Inventor Fumiaki Hirano 2-16-1 Kyobashi, Chuo-ku, Tokyo Shimizu Construction Co., Ltd. (56) References JP-A-60-240446 (JP, A) JP-A-2-232412 ( JP, A) JP-A-1-127713 (JP, A) JP-A-2-55786 (JP, A) JP-A-63-308111 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , (DB name) E02D 3/00 C09K 17/14

Claims (11)

(57) [Claims] 1. A ground improvement material obtained by adding and mixing fibers to an aqueous solution of a hydrophilic material such as agar or gelatin which melts and solidifies due to a temperature change in a temperature range from room temperature to about 100 ° C. 2. The ground improvement material according to claim 1, wherein a fiber and an inorganic material fine powder such as soil, clay, bentonite and sand are added to and mixed with the aqueous solution of the hydrophilic material. 3. The ground improvement material according to claim 1, wherein a fiber and an organic paste such as alpha starch, CMC, protein and the like are added to and mixed with an aqueous solution of the hydrophilic material. 4. The ground improvement material according to claim 1, wherein a preservative is added to an aqueous solution of the hydrophilic material. 5. The ground improvement material according to claim 1, wherein the material is an aqueous solution having an agar concentration of 0.2 to 4%. 6. The ground improvement material according to claim 1, wherein the weight per unit volume is 1.0 to 1.3 t / m ³ . 7. The hydrophilic material is agar, and has a melting temperature of 80-80.
The ground improvement material according to any one of claims 1 to 6, wherein the solidification temperature is 90 ° C and the solidification temperature is 30 to 40 ° C. 8. The soil improvement material contains agar as a hydrophilic material, and has a water permeability of 1 × when solidified due to a decrease in temperature.
2. The method according to claim 1, wherein the pressure is 10 ^-6 to 1 × 10 ^-8 cm / sec.
8. The ground improvement material according to any one of items 7 to 7. 9. The ground improvement material according to claim 1, wherein a displacement absorption groove vertically provided on the ground near the ground wall such as an earth retaining wall, a mountain retaining wall, an underground wall, or the like. Displacement absorbing ground structure, characterized by being filled with water. 10. A backfill method comprising filling a ground improvement material according to any one of claims 1 to 8 on a back surface of a parent pile horizontal sheet pile or a back surface of a shield wall. 11. The ground improvement material according to any one of claims 1 to 8, wherein the ground improvement material according to any one of claims 1 to 8 is filled in the ground below the above-ground structure with a thickness distribution corresponding to an uneven load distribution of the above-ground structure. A unique method of preventing the settlement of structures installed on the ground.