JP2004003306A - Sludge treatment method in prefabricated pile construction, and ground reinforcing structure obtained by method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sludge treatment method and ground reinforcing structure, wherein construction sludge generated in the prefabricated pile construction is not only effectively used, but the total construction cost is reduced, and the ground is reinforced, by using the construction sludge for reinforcing the ground where the prefabricated pile is constructed. <P>SOLUTION: A buried-in pile such as a concrete pile 5 is constructed to penetrate through a soft layer A of the upper part of the ground. Hardening material such as cement is mixed in sludge mixed with excavation liquid such as bentonite waste water discharged in buried-in construction, and the mixture is injected into a post hole 6 dug separately from a pile hole 1 in a construction site. The post hole 6 has a larger diameter and a smaller depth than the pile hole 1, whereby such smaller depth enables excavation without the excavation liquid, and discharged sediment is reused intact as naturally generated earth 8. The sludge containing the hardening material injected into the post pole 6 is hardened so that a soil cement post 10 is formed to directly reinforce the ground, to inhibit liquefaction, and to increase horizontal resisting force at the head of the prefabricated pile 5. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for treating sludge that does not require or minimize landfill disposal by effectively utilizing construction sludge generated during construction of ready-made piles to reinforce the ground on which ready-made piles are constructed. It relates to a ground reinforcement structure obtained by a processing method.
[0002]
[Prior art]
Embedding methods of prefabricated piles such as pre-boring method, excavation method, and rotary press-fitting method are widely used as methods of constructing prefabricated piles because they can reduce pollution such as vibration and noise.
[0003]
The sludge discharged from these construction methods is mixed with drilling fluid consisting of bentonite or cement, fixation fluid around the pile consisting of water and cement, groundwater, etc. It must be treated as construction sludge, which is waste. For this reason, not only is a huge waste disposal cost required, but also in recent years, the receiving capacity of a final disposal site for disposing of these industrial wastes is becoming tight.
[0004]
To cope with such a problem, Patent Literature 1 discloses a method for effectively utilizing construction sludge, in which a cement-based stabilizer is mixed into construction sludge and pressurized, and then granulated to a size of about 5 to 100 mm. A method is disclosed in which the material is effectively used as an embankment, artificial ground, backfill material for a sewer, a drain material or a mat material in a sand drain method.
[0005]
Patent Literature 2 and Patent Literature 3 disclose, as an improvement method, a method of returning crushed powder during granulation to a previous step and treating it, and a surface treatment for preventing elution of alkaline ions on the surface of the granulated improved soil. Is disclosed.
[0006]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 04-049315 [Patent Document 2]
Japanese Patent No. 3122913 [Patent Document 3]
Japanese Patent No. 3122914
[Problems to be solved by the invention]
The method of granulating the improved soil by mixing the cement-based stabilizer with the construction sludge as described above has an advantage that the construction sludge, which is industrial waste, can be effectively used without being discarded. In addition to the mixing of materials, pressurization, dehydration, crushing and classification, surface treatment of the improved soil, and treatment of the crushed powder are required, which requires a certain treatment facility and cost.
[0008]
In addition, large-scale treatment requires large-scale treatment equipment, which cannot be installed at construction sites where construction sludge is generated.Therefore, construction sludge is transported and granulated improved soil is transported to new construction sites. It is necessary and cost is not always economical.
[0009]
In addition, in the embedding method using ready-made piles, when the surface ground is soft, the horizontal resistance of the pile foundation is insufficient.
[0010]
The present invention is intended to solve such problems, the construction sludge generated in the construction of the ready-made pile, by using the ground for the construction of the ready-made pile, not only effective use of construction sludge, It is an object of the present invention to provide a sludge treatment method and a ground reinforcement structure capable of reducing the entire construction cost and reinforcing the ground and piles.
[0011]
[Means for Solving the Problems]
The method for treating sludge according to claim 1 of the present application is characterized in that an improved soil obtained by mixing a hardening material into sludge discharged in a process of embedding a ready-made pile by an embedding method is excavated to bury the ready-made pile ( In addition to the above-mentioned ready-made piles, a pillar made of the improved soil is built in the ground by filling a hole (hereinafter, referred to as a “pillar hole”) excavated separately from the “pile hole”. Thus, the ground strength near the embedded ready-made pile is increased.
[0012]
That is, an improved soil (soil cement) is manufactured by mixing a hardening material such as cement with the discharged sludge, and the improved soil is used in the form of a soil cement pillar or the like in the ground of a pre-fabricated pile construction site using this. In this case, it is possible to increase the strength of the ground near the ready-made pile by making the pillar of the improved soil have a strength higher than the strength of the ground at the site of the ready-made pile.
[0013]
The sludge treatment method according to claim 2 of the present application performs excavation while discharging a drilling liquid mixed with a curable material from a tip bit from an initial stage of excavating a pile hole when constructing a ready-made pile by an embedding method. By doing so, the curable material is mixed with the sludge discharged in the process of construction, and the sludge mixed with the curable material is used as an improved soil, and is filled in a column hole excavated separately from the pile hole. By doing so, a pillar made of the improved soil is built in the ground in addition to the ready-made pile, and the strength of the ground near the embedded ready-made pile is increased by the pillar.
[0014]
In the conventional embedding method, in order to increase the strength of earth and sand around the pile, when excavating to a certain depth or when lifting an excavator such as an auger, it is necessary to inject a hardening material in the form of cement milk etc. Often, the hardened material at the tip of the pile is usually injected from the periphery of the pile, and the cement is formed around the pile by stirring and mixing.
[0015]
However, in the conventional construction method, in the early stage of excavation, a stabilizing liquid such as bentonite is used to prevent collapse of the hole wall, but a large amount of hardening material such as cement is not used.
[0016]
In the invention according to claim 1, the timing of mixing a hardening material such as cement with the sludge is not particularly limited, and the sludge discharged after the use of the equipment for stirring and mixing installed on the ground is used for the cement or the like. However, unlike the conventional method, the method of claim 2 differs from the above-described conventional method in that the drilling liquid containing the curable material is discharged from the tip bit from the initial stage of drilling the pile hole. By performing the above, the sludge is discharged in a state of being already mixed with the curable material, so that equipment for stirring and mixing is not required on the ground, and efficient and inexpensive construction becomes possible.
[0017]
In addition, the curable material in claim 2 is, for example, a material obtained by adding bentonite or the like to cement milk obtained by adding water or the like to cement, and can be discharged from the tip of an excavator such as an auger, In that case, it also has a function as a drilling fluid.
[0018]
According to a third aspect of the present invention, in the sludge treatment method according to the second aspect, a flow path for guiding sludge discharged in a state where the curable material is mixed is provided from the pile hole toward the pillar hole. It is a feature.
[0019]
Generally, when constructing ready-made piles by the embedding method, the sludge discharged from the pile hole has a very high fluidity close to liquid, and in the past, the sludge was collected so that sludge did not accumulate around the pile hole. By dug a shallow pit called, and temporarily store sludge overflowing from the upper end of the pile hole in the Kamaba, the sludge will not hinder the pile construction.
[0020]
According to the third aspect, by providing a flow path from the pile hole to the column hole, the sludge (improved soil) already mixed with the curable material at the time of excavation and discharged can be directly guided to the column hole. It is possible to prevent sludge from accumulating in the surrounding area and hinder the work, eliminating the need for a kiln and making it possible to efficiently build pillars of improved soil near the ready-made piles.
[0021]
In addition, in the sludge treatment method according to claim 1 and claim 2, regarding the significance of increasing the ground strength near the ready-made pile by the pillars of the improved soil, the significance of reinforcing the ground itself, the soft ground that may be liquefied It has the significance of preventing liquefaction, and has the effect of improving the resistance to horizontal displacement of the ground near the ground during an earthquake.
[0022]
Examples of the ready-made pile include a PHC pile, an SC pile, a PRC pile, a PC pile, an ST pile, a node pile, various steel pipe piles, and the like.
[0023]
Examples of the curable material include cement, a cement composition, a slag-based hardener, a lime-based hardener, and other hardenable materials used for producing soil cement, among which cement-based hardeners are generally used. However, there is no particular limitation.
[0024]
In view of ease of handling and cost, a cement-based material is preferable. The soil cement pillar obtained in that case is equivalent to the conventional one.
[0025]
In the present invention, usually, granulation by a complicated processing step as in the prior art described in the section of the prior art is not considered, and the discharged sludge is subjected to a dehydration treatment as needed, Soil cement columns can be built by adding a hardening material such as cement and pouring it into a drilled hole by a conventional method, so basically, sludge generated at the construction site is all collected by simple equipment in the same construction site. Can be processed.
[0026]
The mixing ratio of the sludge and the curable material is not particularly limited, but it is preferable to add the curable material in an amount of 50 to 500 kg / m ³ depending on the water content of the sludge in order to increase the strength of the surrounding ground.
[0027]
As described above, the present invention treats construction sludge at a construction site (construction site where construction sludge is generated), and at the same time, effectively uses the sludge itself to increase the ground strength at the site, suppress liquefaction, or improve the pile foundation. This is to improve the resistance to horizontal displacement.
[0028]
Moreover, even when the improved soil is produced by mixing the curable material with the sludge discharged to the ground according to the invention of claim 1, no special equipment is required except for the equipment for mixing the sludge and the curable material. Further, the invention according to claim 2 does not require a mixing facility on the ground, and is excellent in economy.
[0029]
As a method of mixing and kneading the curable material with the sludge, when producing the improved soil using the sludge discharged to the ground in the invention according to claim 1, the sludge stored in the tank is mixed with cement or the like using a mixer. Method of mixing with curable material, method of adding and mixing curable material directly into tank storing sludge, method of pumping generated sludge into pillar hole using pump, mixing with cement slurry etc. at the tip, sludge A method in which a curable material such as cement is added while filling with a pump or the like, and stirring is performed in a pillar hole using an auger or the like is considered. Incidentally, in the case of the invention according to claim 2, as described above, the curable material is discharged from the pile hole in a state of being mixed.
[0030]
Since the depth of the column made of the improved soil can be usually shallow, it can be constructed inexpensively by setting it to a depth that does not require a drilling fluid such as bentonite mud without other special factors.
[0031]
The method of drilling a hole (column hole) to be drilled separately from the hole drilled for embedding the ready-made pile is not particularly limited, but an excavator such as an auger used for construction of the ready-made pile can be used. At that time, by excavating without using a drilling liquid composed of water, bentonite, cement, or the like, the generated soil has a cone index of 200 kN / m ² or more in most cases, and can be treated as general generated residual soil. The cone index used here is used for judging the quality of the treated soil, and is based on the JGS T 716 of the "Joint Cone Index Test of Compacted Soil" of the Japanese Geotechnical Society. Further, an excavation method by a casing method can be used.
[0032]
Claim 4 limits the case where the depth of the pillar hole is shallower than the nearby pile hole in the sludge treatment method according to Claims 1 to 3.
[0033]
The support of buildings and other superstructures is basically supported by piles arranged at predetermined positions in accordance with the form of the structure, and the position and diameter of pillars of improved soil which also serves as sludge treatment of the present invention are not necessarily limited. However, shallower than prefabricated piles is advantageous from the standpoint of ground reinforcement, such as improving workability and resistance to horizontal displacement of the pile foundation.
[0034]
In addition, the portion that may be liquefied is often the upper layer of the ground, and it is effective to reinforce the upper layer of the ground from the viewpoint of pile head reinforcement.
[0035]
In addition, when the geology of the ground at the construction site is uneven, when the ground is sloping, when the form of the structure is special, etc., the length of the pile to be constructed may vary depending on its position. The hole was made shallower than the nearby pile hole.
[0036]
Specifically, in the sludge treatment method according to any one of claims 1 to 4, the depth of the column hole for constructing the column with the improved soil is preferably about 1 m or more and 10 m or less, and more preferably 2 m or more and 6 m or less. .
[0037]
If the column made of the improved soil is less than 1 m, a sufficient volume is not secured from the viewpoint of sludge treatment, and sludge utilization efficiency is poor. If the depth is more than 10 m, groundwater is likely to flow out, and depending on the soil quality, the hole wall may collapse without using drilling liquid, making it difficult to excavate, and there may be a problem in filling the improved soil. In addition, when the drilling liquid is used, as described above, it is difficult to treat the soil as general generated soil.
[0038]
Claim 5 is the sludge treatment method according to Claims 1 to 4, wherein the diameter of the pillar hole for constructing the pillar by the improved soil is larger than the diameter of the neighboring pile hole for embedding the ready-made pile. The case is limited.
[0039]
As described above, in general, the depth of pillars of improved soil is often much shallower than the depth of ready-made piles.In order to use all sludge discharged during the burial process of ready-made piles at the generation site, It is necessary to increase the diameter of pillars of the improved soil, increase the number of pillars, or both. The same applies basically when part of the sludge is used outside the generation site.
[0040]
In addition, in terms of construction, it is easier to drill a shallow hole with a larger diameter than to drill a large number of holes, and a ground reinforcing effect can be obtained.
[0041]
The diameter of the pillar hole is desirably 400 mm or more and 1200 mm or less. Although it is related to the amount of generated sludge determined according to the pile diameter and the pile length, generally, when the thickness is less than 400 mm, the volume that can process one sludge is small, and in order to process the same amount of sludge, and for ground reinforcement. Therefore, the number of lines required increases, and the efficiency becomes extremely low.
[0042]
On the other hand, when it is larger than 1200 mm, it becomes difficult to excavate with a conventional general ready-made pile machine. However, if the excavation depth is shallow and a backhoe can be used, a larger diameter excavation is conceivable.However, it is not possible to make the diameter significantly larger from the viewpoint of workability of filling the improved soil and affecting other construction works. Not preferred.
[0043]
The ground reinforcement structure according to claim 6 of the present application includes a hardening material or a hardening material in sludge generated when a hole is excavated to bury the ready-made pile in a ground on which a plurality of ready-made piles are constructed. Pillars made of the improved soil mixed with drilling liquid are dispersed and arranged in the vicinity of the ready-made stakes or between the ready-made stakes under the aforementioned conditions as appropriate. In addition, assuming specific numerical values for the vicinity in this case, in consideration of ground reinforcement and improvement of horizontal resistance in the event of an earthquake, it is desirable that the distance between the ready-made pile and the outer periphery of the column be within 2 m.
[0044]
Although the form of the dispersal arrangement is not particularly limited, there are two cases: one is to disperse the ground to some extent evenly to reinforce the ground as uniformly as possible, and the other is to arrange it as close to the ready-made pile as possible to improve the reinforcing effect of the pile head. Can be
[0045]
Claim 7 restricts the case in which the column made of the ready-made pile and the improved soil is distributed and arranged in a wall shape in the ground on which the ready-made pile is constructed, in the ground reinforcing structure according to claim 6. .
[0046]
As the soil improvement type using the conventional soil cement columns, when the soil cement columns are also expected to have a pile-like function, when the pile type arrangement is used, when one or more rows of wall-like arrangements are used, There may be a case of a wall-like arrangement surrounding the cell, a case of a lattice-like wall arrangement, and the like. In addition, there are a case where the columns are dispersed and a case where a part of the columns is overlapped.
[0047]
However, in each case, only the soil cement column is used, or soil cement is arranged around the column to reinforce the ready-made pile. In the present invention, a ready-made pile as an embedded pile and columns made of improved soil are mixed, and claim 7 limits the case where these are arranged in a wall shape. If the columns made of the improved soil are continuously arranged in a row, they can be connected to form a wall.
[0048]
Claim 8 restricts the case in which the pillar made of the improved soil is shorter and thicker than a nearby ready-made pile in the ground reinforcement structure according to claim 6 or 7, and has a form of a pillar made of the improved soil. Corresponds to a combination of claims 4 and 5.
[0049]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows the basic concept of the sludge treatment method according to claim 1 of the present application, in which an embedded pile such as a precast concrete pile 5 is constructed so as to penetrate the soft layer A, and discharge is performed during this embedding. A hardening material such as cement is mixed with sludge mixed with a drilling fluid such as bentonite muddy water, and the mixture is placed in a construction site at a diameter larger and shorter than the hole 1 excavated separately from the hole 1. 6, the sludge can be treated without leaving it outside the construction site.
[0050]
On the other hand, since the column hole 6 is shallow, excavation can be performed without using a drilling liquid, and the earth and sand discharged by excavation of the column hole 6 can be reused as the general generated soil 8 as it is.
[0051]
Ideally, all sludge discharged during embedding of piles should be disposed of at the same construction site for effective use. It could be. Conversely, when sludge is insufficient, a part of the general generated soil 8 may be used.
[0052]
2 to 6 show a construction procedure in a specific embodiment of the sludge treatment method according to claim 1 of the present application, and the construction is performed according to the following procedure.
[0053]
The pile hole 1 is excavated by the auger 2, and the sludge 3 containing the excavated liquid discharged at that time is stored in the tank 4 (see FIG. 2).
[0054]
A ready-made pile 5 such as a concrete pile is sunk into the pile hole 1. At this time, the sludge 3 is discharged and stored in the tank 4 (see FIG. 3).
[0055]
An auger 7 excavates a shallow column hole 6 having a diameter larger than the pile hole 1 near the buried ready-made pile 5 (see FIG. 4). As the auger 7, the auger 2 for excavating the pile hole 1 in FIG. 2 may be diverted, and the attachment and the like are changed as necessary.
[0056]
The excavation of the column hole 6 is performed without using the drilling liquid, so that the discharged earth and sand can be reused as the general generated soil 8. Note that FIG. 4 does not show that the column hole 6 is excavated after the ready-made pile 5 is laid in the pile hole 1, and that part of the excavation may proceed simultaneously depending on the situation.
[0057]
A hardening material such as cement is mixed with the sludge 3 stored in the tank 4, and soil cement as the improved soil 9 is filled in the column hole 6 (see FIG. 5).
[0058]
As the improved soil 9 hardens in the column hole 6, a soil cement column 10 having a ground reinforcing effect is formed in the vicinity of the ready-made piles 5 and between them. In addition, by arranging the soil cement column 10 at least in the vicinity of the ready-made stake 5, the horizontal resistance at the head of the ready-made stake 5 can be increased, and the effect of preventing liquefaction of the ground during an earthquake can be expected.
[0059]
7 to 9 show the construction procedure in one embodiment of the sludge treatment method according to claim 2 of the present application, and the construction is performed according to the following procedure.
[0060]
A soil cement column hole 6 is excavated in advance near the excavated pile hole 1 with an auger 7 (see FIG. 7). When no drilling fluid or the like is used, the excavated soil can be treated as the generally generated soil 8.
[0061]
The drill hole 1 is excavated while the drilling liquid mixed with the curable material (curable material + water, and if necessary bentonite is added) is discharged from the tip bit 2 a of the auger 2, and the column hole 1 to the column hole 6. The sludge 3 containing the curable material overflowing from the pile hole 1 is poured into the column hole 6 through the groove 21 as a flow path (see FIG. 8).
[0062]
The ready-made stake 5 is built in the stake hole 1, and the sludge 3 containing the hardened material which overflows is similarly poured into the column hole 6 through the groove 21 as a flow path (see FIG. 9).
[0063]
FIG. 10 is a flowchart showing a construction procedure in the embodiment of FIGS. 7 to 9 described above. However, the flowchart shown in FIG. 10 is merely a specific example, and various modifications can be made without departing from the spirit of the present invention.
[0064]
The drilling liquid, the root compaction liquid and the pile circumference fixing liquid in the flowchart of FIG. 10 are respectively obtained by adding bentonite and the like to a hardening material such as cement and water as needed. Increase the amount of addition.
[0065]
The amount of the curable material such as cement milk is determined so that the material cured as soil cement has higher strength than the surrounding ground.
[0066]
FIG. 11 shows an example of arrangement of ready-made piles and soil cement columns in one embodiment of the ground reinforcement structure of the present invention.
[0067]
In the example of FIG. 11A, soil cement columns 10 are arranged in a grid-like wall shape near or between ready-made piles 5 as embedded piles that support the upper structure 11, and the ground is reinforced in a lattice wall structure. Meanwhile, the horizontal resistance at the head of the ready-made pile 5 is increased.
[0068]
In the example of FIG. 11B, the soil cement columns 10 are arranged in a wall shape near or between the ready-made piles 5 as embedded piles that support the upper structure 11, and while the ground is reinforced in a wall structure, the ready-made piles are provided. The horizontal resistance at the head of No. 5 is increased.
[0069]
In the example of FIG. 11C, the soil cement columns 10 are arranged in a pile shape between the ready-made piles 5 as embedded piles that support the upper structure 11, and while reinforcing the ground in a pile structure, Increases horizontal resistance at the head.
[0070]
In addition, various arrangements of the soil cement columns 10 are conceivable from the viewpoint of ground reinforcement, prevention of liquefaction, increase in horizontal resistance at the pile head, and the like.
[0071]
【The invention's effect】
In the sludge treatment method of the present invention, at the same time as treating construction sludge at a construction site using a ready-built pile embedding method, the sludge itself is effectively used as improved soil in the form of soil cement columns, etc. By constructing the reinforcing structure, the ground strength can be increased, liquefaction can be suppressed, or the resistance of the pile foundation to horizontal deformation can be improved.
[0072]
There is no need for complicated processes or special equipment for sludge treatment and reuse. Especially in the case of the second aspect, no equipment for stirring and mixing is required on the above-ground part, and the economy is excellent.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a basic concept of a sludge treatment method in construction of a ready-made pile according to the present invention.
FIG. 2 is a sectional view showing a construction procedure in one embodiment of the invention according to claim 1 of the present application.
FIG. 3 is a sectional view showing a construction procedure following FIG. 2;
FIG. 4 is a cross-sectional view showing a construction procedure following FIG. 3;
FIG. 5 is a sectional view showing a construction procedure following FIG. 4;
FIG. 6 is a sectional view showing a construction procedure following FIG. 5;
FIG. 7 is a cross-sectional view showing an outline of a construction procedure in one embodiment of the invention according to claim 2 of the present application.
FIG. 8 is a sectional view showing a construction procedure following FIG. 7;
FIG. 9 is a sectional view showing a construction procedure following FIG. 8;
FIG. 10 is a flowchart showing a specific example of a construction procedure in the embodiment of FIGS.
FIG. 11 is a plan view showing an example of the arrangement of ready-made piles and soil cement columns in one embodiment of the ground reinforcement structure of the present invention.
[Explanation of symbols]
A: soft layer, B: support layer,
DESCRIPTION OF SYMBOLS 1 ... Pile hole, 2 ... Auger, 2a ... Tip bit, 3 ... Sludge, 4 ... Tank, 5 ... Ready-made pile, 6 ... Pillar hole, 7 ... Auger, 8 ... General soil, 9 ... Improved soil, 10 ... Column , 11 ... superstructure, 21 ... groove

Claims (8)

By filling the excavated hole separately from the hole excavated for embedding the ready-made pile, the improved soil obtained by mixing the hardening material into the sludge discharged in the process of constructing the ready-made pile by the embedding method is used, A method for treating sludge in the construction of a ready-made pile, comprising: building a pillar made of the improved soil in the ground in addition to the ready-made pile, and increasing the strength of the ground near the embedded ready-made pile by the pillar. When constructing a ready-made pile by the embedding method, drilling while discharging the drilling liquid mixed with hardening material from the tip bit from the initial stage of drilling a hole for embedding the ready-made pile, The curable material is mixed with the discharged sludge, and the sludge mixed with the curable material is used as an improved soil, and is filled in a hole excavated separately from the hole excavated for embedding the ready-made pile. Thus, a method of treating sludge in the construction of a ready-made pile is characterized in that a pillar made of the improved soil is built in the ground in addition to the ready-made pile, and the strength of the ground near the embedded pile is increased by the pillar. A flow path for guiding sludge discharged in a state where the curable material is mixed is provided from a hole for embedding the ready-made pile to a hole excavated separately from the hole. A method for treating sludge in the construction of ready-made piles according to claim 2. 4. The sludge treatment method according to claim 1, 2 or 3, wherein a depth of the hole for constructing the pillar made of the improved soil is shallower than a nearby hole excavated for embedding a ready-made pile. The diameter of a hole for constructing a pillar made of the improved soil is larger than the diameter of a nearby hole excavated for embedding the ready-made pile. Sludge treatment method. In the ground where a plurality of ready-made piles have been constructed, a column made of an improved soil obtained by mixing a drilling liquid containing a hardening material or a hardening material into sludge generated when a hole is excavated to embed the ready-made pile, A ground reinforcement structure, wherein the ground reinforcement structure is dispersedly arranged near the ready-made piles. The ground reinforcement structure according to claim 6, wherein the pillars made of the ready-made pile and the improved soil are distributed and arranged in a wall shape in the ground on which the ready-made pile is constructed. The ground reinforcement structure according to claim 6 or 7, wherein the pillar made of the improved soil is shorter and thicker than the neighboring ready-made pile.

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