JP2006336216A - Ground improvement construction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ground improvement construction method capable of reducing cost, and capable of increasing efficiency in construction, by rationally preparing an improvement body having a large diameter. <P>SOLUTION: This ground improvement construction method prepares the columnar improvement body 14 in the ground G by filling a curing material in the ground G by injecting the curing material from a lower stage injection hole 3 while cutting the ground G by injecting cutting water from an upper stage injection hole 2 when pulling up while rotating an injection rod 1 inserted into the ground. Unset pw or qw is determined by setting any of ϕc and pw or qw from a correlation between cutting capacity pw×qw and a cutting diameter ϕc of the ground expressed by the product of injection pressure pw of the cutting water and a delivery quantity qw per unit time of the cutting water. Unset ps or Qs is determined by setting any of ϕ and ps or Qs from a correlation between improvement body preparing capacity ps×Qs and a diameter ϕ of the improvement body expressed by the product of injection pressure ps of the cutting material and an injection quantity Qs per the unit depth of the curing material. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a ground improvement method, and more particularly, to a high-pressure jet stirring method for creating an improved body in the ground by jetting a hardener into the ground and mixing with stirring.

Among the ground improvement methods that consolidate the soft ground, the jet agitation method for creating a consolidated improvement body by high-pressure injection of cement-based hardener into the ground is the CJG (column jet grout) method, R.C. J. et al. P. Construction methods (registered trademark, also referred to as “rosin jet pile method”) and Superjet-midi (super jet midi) method (“SUPERJET method” is a registered trademark) are representative methods (Patent Documents) 1).
When the CJG method is pulled up while rotating a triple tube rod having two upper and lower injection holes at the tip, the super high pressure water surrounded by compressed air is discharged from the upper injection holes to cut the ground, This is a construction method of creating a cylindrical improvement body having a diameter of about 2 m in the ground by discharging the curing material from the lower injection holes and filling the ground with the curing material (see Patent Document 2).
R. J. et al. P. The construction method, like the CJG method, uses a triple tube rod with two upper and lower injection holes at the tip, but discharges ultra-high pressure water surrounded by compressed air from the upper injection hole. This is a method of filling the ground with hardened material by cutting the ground in a smaller diameter range and discharging the hardened material surrounded by compressed air from the lower injection holes to further cut the ground. In addition, a cylindrical improvement body having a diameter of about 2.8 m can be formed.
On the other hand, in the Superjet-midi construction method, a double tube rod having a horizontally opposed one-stage injection hole at the tip is used, and first, a hole called a guide hole having a diameter of about 20 cm is formed in the ground until a predetermined depth is reached. After the double tube rod is built, the ground and the hardened material are cut while the ground is being cut by spraying the super high pressure and large discharge amount of the hardened material surrounded by compressed air from the opposed injection holes provided at the tip. And a cylindrical improvement body having a diameter of about 3.5 m can be formed in the ground.
JP 2003-286717 A (2nd page, FIG. 7) Japanese Examined Patent Publication No. 58-27364 (page 1-2, Fig. 1-2)

Table 1 shows the injection rate of the hardened material and cutting water of the above three methods. Here, the injection rate is the ratio of the injection amount to the improved volume, the injection rate α _S is the injection ratio of the hardened material to the improved volume, and the total injection rate α is the injection ratio of (hardening material + cutting water) to the improved volume. It is.

From the table, R.D. J. et al. P. It can be seen that the construction method and Superjet-midi construction method have a smaller total injection rate α than the CJG construction method. Since the amount of mud drained from the ground depends on the amount of injection of the upper and lower jets, the smaller the total injection rate α, the smaller the waste mud treatment (industrial waste) cost. Moreover, at present, the construction method that can produce an improved body having a diameter of 3 m or more is R.I. J. et al. P. Only the construction method (if the rod pull-up time is lengthened, an improved body having a diameter of 3 m or more can be created) and the Superjet-midi construction method.
However, since both methods are cutting the ground using a hardener, the waste mud mixed with the hardener is discharged to the ground surface, resulting in poor material efficiency to obtain the required improved strength. . Moreover, in both methods, in the case of viscous soil with a high adhesive strength of 50 kN / m ² or higher (N value of 3 or higher), the viscosity of the waste mud increases due to the effect of cutting by the hardener. This will cause problems and will require prior advance water cutting. In addition, due to this influence, it is in a situation where prior water cutting is absolutely necessary even in deep construction of 20 m or more. As described above, both methods have a problem that the construction efficiency is deteriorated in viscous soil with high adhesive strength or in deep construction.

In order to solve this problem, in order to make it harder to mix the hardener in the mud, it is only necessary to combine the CJG method of performing ground cutting with preceding water and the Superjet-midi method of creating a large-diameter improved body. In that case, however, the larger the diameter, the greater the amount of mud and the longer the construction. Conventionally, there has been no ground improvement method that can solve these problems and reduce costs and increase the efficiency of construction.
An object of this invention is to provide the ground improvement construction method which solves the above-mentioned problem and can aim at cost reduction and construction efficiency improvement.

  In order to achieve the above object, the present invention inserts an injection rod having an injection hole at the tip into the ground, and when the injection rod is pulled up while rotating, the curing material is injected from the injection hole, In the ground improvement method in which a columnar improvement body is formed, the improvement body generation capacity ps × Qs represented by the product of the injection pressure ps of the hardener and the injection amount Qs per unit depth of the hardener and the improvement From the correlation with the diameter φ of the body, in addition to the diameter φ of the improved body, by setting either the injection pressure ps of the curing material or the injection amount Qs per unit depth of the curing material, Determine the injection pressure ps of the curing material not set or the injection amount Qs per unit depth of the curing material, and set or determined the injection pressure ps of the curing material and the unit depth of the curing material Injection amount An improved body having a diameter φ is created using Qs.

  Also, the present invention inserts an injection rod having two upper and lower injection holes at the tip into the ground, and when cutting the injection rod while rotating, injects cutting water from the upper injection hole and lower injection. In a ground improvement method in which a hardened material is injected from a hole to form a columnar improvement body in the ground, cutting represented by the product of the cutting water injection pressure pw and the cutting water discharge amount qw per unit time. From the correlation between the capacity pw × qw and the ground cutting diameter φc, in addition to the cutting diameter φc, either the cutting water injection pressure pw or the cutting water discharge amount qw per unit time is set. Thus, the injection pressure pw of the cutting water that is not set or the discharge amount qw per unit time of the cutting water is determined, and the injection pressure ps of the hardening material and the injection amount Qs per unit depth of the hardening material are determined. When From the correlation between the improved body creation capacity ps × Qs expressed by the product and the diameter φ of the improved body, in addition to the diameter φ of the improved body, the injection pressure ps of the hardened material or the unit depth of the hardened material By setting any one of the injection amount Qs, the injection pressure ps of the hardened material that is not set or the injection amount Qs per unit depth of the hardened material is determined, and the cutting or the cutting that has been set or determined is determined. Using the diameter φc, the cutting water injection pressure pw, the cutting water discharge amount qw per unit time, the hardening material injection pressure ps, and the hardening material injection depth Qs per unit depth, the diameter φ It is characterized by creating an improved body.

  The inventors conducted a field experiment of the high-pressure jet agitation method, and the cutting power pw × qw is high between the ground cutting diameter φc, and the improved body creation capacity ps × Qs and the improved body diameter φ are high. We found that a correlation exists. The present invention utilizes these correlations for the creation of an improved body, which makes it possible to rationally create a large-diameter improved body, thereby reducing costs and increasing the efficiency of construction. it can.

  In the present invention, by using the correlation between the cutting ability and the cutting diameter of the ground, and the correlation between the improved body creation ability and the diameter of the improved body, the jetting pressure of the cutting water, the discharge amount per unit time of the cutting water , And the injection pressure of the curing material and the injection amount per unit depth of the curing material can be determined. Thereby, it is possible to rationally create a large-diameter improved body, and cost reduction and construction efficiency can be achieved.

  The present invention mainly rotates when the injection rod is pulled up (including the case of forward and reverse rotation). The cutting water is injected from the upper injection hole at the tip of the injection rod, and the hardening material is injected from the lower injection hole of the injection rod. Although it is a ground improvement method, the ground improvement method that sprays only the hardened material without using cutting water, the ground improvement method that jets the hardened material with compressed air, or another injection hole close to the injection hole of the hardened material, The present invention can also be applied to a ground improvement method in which a reactive material that promotes hardening of the hardened material is jetted in accordance with the jetting of the hardened material.

Hereinafter, an embodiment of a ground improvement method according to the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view of an injection rod used in the present invention, and FIG. 2 is a longitudinal sectional view of the tip of the injection rod.
The injection rod 1 is a triple tube rod composed of an outer tube 4, an intermediate tube 5, and an inner tube 6, and is provided with an upper injection hole 2 and a lower injection hole 3 on the side surface of the distal end portion 1 a thereof. 2 is comprised from the 1st injection hole 2a for injecting the ultra high pressure cutting water, and the 2nd injection hole 2b for injecting the compressed air provided in the outer peripheral part of the 1st injection hole 2a. .
The first injection hole 2a, the second injection hole 2b, and the lower injection hole 3 communicate with the first flow path 7, the second flow path 8, and the third flow path 9, respectively, and are connected to the rear end portion 1b of the injection rod 1. Through the attached triple tube swivel 10, ultrahigh pressure cutting water, compressed air, and hardened material are respectively pumped to the first flow path 7, the second flow path 8, and the third flow path 9.

  In the case of this injection rod 1, since the ultra-high pressure cutting water surrounded by compressed air is ejected from the upper injection hole 2, it is possible to obtain both effects of extending the flight distance and discharging the cutting soil by the air lift effect, Since only the hardened material is injected from the lower injection holes 3, the air lift effect is not so much generated in the hardened material, and waste of the hardened material can be prevented.

Next, the construction procedure of the present invention will be described with reference to FIG.
First, it inserts in the ground G, rotating the casing tube 12 using the boring machine 11, and forms a guide hole to predetermined depth (refer Fig.3 (a)). A drilling bid 12a is attached to the tip of the casing tube 12, and a guide hole is formed by drilling the ground G with the drilling bid 12a while supplying water from the rear end 12b of the casing tube 12. Is done.
Next, the injection rod 1 is inserted into the casing tube 12 using the crane 13 (see FIG. 3B), and the crane tube 13 is used to insert the casing tube 12 to a height that does not hinder the formation of the improved body 14. (See FIG. 3C). Depending on the state of the ground G, the casing tube 12 may be completely pulled out from the ground G.
Thereafter, the injection rod 1 is gradually pulled up using the column machine 15 (see FIG. 3D). At this time, ultrahigh-pressure cutting water, compressed air, and hardened material are respectively pressed into the injection rod 1 through the triple tube swivel 10, and ultrahigh-pressure cutting water surrounded by compressed air is injected from the upper injection holes 2. While cutting the ground G, a hardened material made of a self-hardening material such as cement is injected from the lower injection hole 3 to form a cylindrical improvement body 14 from below to above. When the creation of the improved body 14 is completed, the injection rod 1 and the remaining casing tube 12 are pulled out from the ground G and the guide holes are filled (see FIG. 3E).

  In addition, in the case of the ground improvement method by injection | pouring of only a hardening material, the upper stage injection hole 2 which injects the cutting water shown in FIG. 2 is lose | eliminated, and only a hardening material is injected. Moreover, when injecting a hardening material with compressed air, a compressed air injection hole is provided around the injection hole of a hardening material, and the hardening material enclosed with compressed air is injected. Furthermore, when adding a reaction material that promotes curing of the hardened material, the triple tube shown in FIG. 2 is a quadruple tube, and the reaction material injection hole communicating with the newly opened flow path is used as the hardener injection hole. It is provided separately in the vicinity, and the reactive material is sprayed together with the curing material.

  Although the construction procedure is as described above, the problem here is how to economically construct an improved body having a predetermined improved diameter. Conventionally, settings of cutting water and hardener injection rate, cutting water discharge amount and spray pressure, hardener discharge amount and spray pressure have been made empirically or by trial and error, so these settings are economical. It wasn't clear whether it was something. Therefore, the inventors of the present invention confirmed the correlation between the improved diameter and the set value through experiments, and obtained the knowledge described later. Hereinafter, description will be made based on experimental results.

FIG. 4 shows the correlation between the cutting ability pw × qw represented by the product of the cutting water injection pressure pw and the discharge amount qw per unit time of the cutting water and the ground cutting diameter (diameter) φc. is there. As experimental conditions at this time, the pulling time of the injection rod 1 is set to 10 minutes / m and 15 minutes / m, and the rotation speed of the injection rod 1 is set to rotate once at a rising pitch of 2.5 cm. Therefore, when the pulling time is 10 minutes / m, the rotation speed is 4 rotations / minute, and when the pulling time is 15 minutes / m, the rotation speed is 2.7 rotations / minute. The pressure of the compressed air was 1 MPa.
FIG. 5 shows the correlation between the improved body production capacity ps × Qs expressed by the product of the injection pressure ps of the hardened material and the injection amount Qs per unit depth of the hardened material and the diameter (diameter) φ of the improved body. It is a thing. As experimental conditions at this time, as in the case of the cutting water, the pulling time of the injection rod 1 was 10 minutes / m and 15 minutes / m, and the rotation speed of the injection rod 1 was 2.5 cm ascending pitch. It was made to rotate once.
Curves (1) and (2) in the figure are correlation equations obtained by regression analysis based on experimental values, and are represented by the following equations.
φc = 1.973 · ln (pw × qw) +13.6 (1)
φ = 1.985 · ln (ps × Qs) +4.24 (2)
However, the unit of each parameter is as follows.
pw, ps: MPa, qw: liter / min, Qs: m ³ / m, φc, φ: m

Here, the equations (1) and (2) are converted into equations (3) and (4), respectively.
pw × qw = exp ((φc + 13.6) /1.973) (3)
ps × Qs = exp ((φ + 4.24) /1.985) (4)
Further, the discharge amount qs per unit time of the cured material is given by the equation (5).
qs = 1000 · Qs / t (5)
Here, t is the pulling-up time per unit length of the injection rod (min / m), and the coefficient 1000 in the equation (5) is that the unit of qs is liter / min and the unit of Qs is m ³ / m. It depends.

Using the equation (3), the cutting water injection pressure pw (referred to as cutting water pressure in the figure) and the cutting water when the ground cutting diameter φc is changed in the range of 3.0 to 5.0 m. A correlation with the discharge amount qw per unit time is shown in FIG. It can be seen from the figure that in order to obtain the same cutting diameter φc, the discharge amount qw per unit time of the cutting water may be smaller as the cutting water injection pressure pw is larger. It can also be seen that in order to increase the cutting diameter φc, the cutting water injection pressure pw and the cutting water discharge amount qw per unit time must be increased.
Similarly, by using the equations (4) and (5), the injection pressure ps of the cured material when the diameter φ of the improved body is changed in the range of 3.0 to 5.0 m (in the figure, the cured material pressure and 7) and the discharge amount qs per unit time of the cured material are shown in FIG. Here, FIG. 7A shows the case where the pulling-up speed of the injection rod is 10 minutes / m, and FIG. 7B shows the case where it is 15 minutes / m. Similarly to FIG. 6, it can be seen that in order to increase the diameter φ of the improved body, it is necessary to increase the injection pressure ps of the curing material and the discharge amount qs per unit depth of the curing material.

FIG. 8 sets appropriate values for the cutting water injection pressure pw and the hardening material injection pressure ps, and the values are shown in FIG. 4 and FIG. 5 (representation of relational expressions (1) and (2)). The cutting water injection rate αw and the hardening material injection rate αs are calculated by fitting, and the correlation between the cutting water injection pressure pw and the cutting water injection rate αw at the pulling-up times 10 minutes / m and 15 minutes / m of the injection rod 1 and The correlation between the curing material injection pressure ps and the curing material injection rate αs is obtained. Here, the cutting water injection rate αw is the injection amount Qw (qw × t) per unit depth of the cutting water with respect to the cutting volume Vc per unit depth by the ground cutting diameter φc, and the hardener injection rate αs is The injection amount Qs per unit depth of the hardened material with respect to the improved volume V per unit depth due to the diameter φ of the improved body.
From the figure, it can be seen that when the hardening material injection rate αs is set to 30%, the injection pressure ps of the hardening material may be about 20 MPa. The specifications can be set similarly for the cutting water.

Next, the hardening material injection rate αs and the cutting water injection rate αw that affect the cost in the ground improvement method according to the present invention will be considered from FIGS.
For the hardened material, a curve appears when the hardener injection rate αs is 30% or more (see FIG. 8). This is because the change in the hardener injection rate αs with respect to the change in the injection pressure ps of the hardener. This means that it becomes very large, that is, the quality (strength and improved diameter of the improved body) tends to vary. On the other hand, when the curing material injection rate αs is 10% or less, the injection pressure ps of the curing material must be greatly varied even if the curing material injection rate αs is slightly varied, that is, the curing material injection rate αs is 10%. In the following, neither construction nor cost will be affected. From this, it can be seen that the curing material injection rate αs is preferably in the range of 10 to 30%.
For cutting water, considering that the pull-up time is about 10 minutes / m at the fastest, the quality (improved diameter) is likely to vary when the cutting water injection rate αw is 40% or more, as with the hardened material. When the cutting water injection rate αw is 10% or less, there is no need for construction and cost. Accordingly, the cutting water injection rate αw is preferably in the range of 10 to 40%.
As another factor, it is necessary to consider the total injection rate α (= αw + αs) obtained by adding the cutting water injection rate αw and the hardener injection rate αs. This upper limit should be 50% or less, more preferably 45% or less, with a view to reducing the amount of mud discharged from the conventional method.
From the above, it is preferable to set the total injection rate α to 20 to 50%, more preferably 20 to 45%, while setting the curing material injection rate αs to 10 to 30%.

Specific examples will be described below.
First, the cutting water injection rate αw and the hardener injection rate αs are set so that the total injection rate α is, for example, 40%.
Here, assuming that αw = 20%, αs = 20%, and the pulling-up time per unit length of the injection rod is t = 10 minutes / m, the cutting water injection pressure pw = 30 MPa and the hardening material injection are shown in FIG. The pressure ps = 25 MPa.
The construction specifications for the diameter φ of the improved body can be set as shown in Table 2 using FIG. 6 and FIG.

  In addition, it is not necessary to stick to the construction specifications shown here, and if the curing material injection rate αs is 10 to 30%, the total injection rate α is 20 to 50%, more preferably 20 to 45% or less, (3) Various construction specifications for the diameter φ of the improved body can be set using the formula and the formula (4). For example, in the case where the improved body strength is set to be large, the construction specification is selected so that the hardening material injection rate is αs = 30% and the cutting water injection rate is αw = 10-20%, more preferably 10-15%. That's fine.

By the way, in the above description, the cutting water injection rate αw and the hardened material injection rate αs are considered in FIG. 8, but the injection rate that affects the cost is examined when the cutting water and the injection pressures pw and ps of the hardened material are examined. It can be seen that the practical and effective injection pressures pw and ps in the vicinity of 10% which is the lower limit of the pressure are 50 to 60 MPa.
Therefore, an embodiment in the case of setting the cutting water and the injection pressures pw and ps of the cured material will be described.
Here, the injection pressure pw of the cutting water is 60 MPa (the injection pressure of compressed air is about 1 MPa), and the injection pressure ps of the hardened material is 50 MPa. The cutting water injection rate αw and the hardened material injection rate αs at this time are 10% for each pulling time of 10 minutes / m. When this set value is calculated by applying it to FIGS. 6 and 7A, the construction specifications for each improved diameter are as shown in Table 3.

  Thus, since the construction specifications for the diameter φ of an arbitrary improved body are set rationally, it is possible to select a construction method having the shortest construction period and having a cost reduction effect. The main breakdown of construction costs consists of material costs, labor costs, machinery / equipment costs, and mud drainage costs, and these are combined to select the minimum cost. In order to reduce the waste mud cost, it is necessary to set the pump to a high discharge pressure in order to reduce the waste mud. However, in this case, the pump becomes special, so the cost of machinery and equipment becomes expensive. Actually, the optimum construction specification is determined in consideration of apportionment around this area.

  In the ground improvement method according to the present embodiment, the correlation formula (1) between the cutting ability pw × qw and the ground cutting diameter φc, and the correlation formula (2) between the improved body creation ability ps × Qs and the diameter φ of the improved body (2). ) Can be used to determine the cutting water injection pressure pw, the discharge amount qw per unit time of the cutting water, the injection pressure ps of the hardener, and the injection amount Qs per unit depth of the hardener. Thereby, it is possible to rationally create a large-diameter improved body, and cost reduction and construction efficiency can be achieved.

As mentioned above, although embodiment of the ground improvement construction method concerning this invention was described, this invention is not limited to said embodiment, In the range which does not deviate from the meaning, it can change suitably. For example, in the above embodiment, the correlation equations (1) and (2) are logarithmically approximated, but it goes without saying that other functions such as linear approximation and polynomial approximation may be used. In short, it is only necessary to obtain the desired function in the present invention.
The knowledge of the present invention can also be applied to the ground improvement method by injection of only the hardener, and the above-described equations (2), (4), FIG. 5 and FIG. 7 can be used. In the case of the ground improvement method in which the hardened material is injected together with the compressed air, since it affects the improved diameter, the correlation is different from the case where there is no compressed air as described above. In any case, the idea of the present invention can be applied. In addition, the reactive material is cut even in the ground improvement method in which the reactive material is injected in accordance with the injection of the hardened material from the reactive material injection hole provided close to the hardened material injection hole along with the injection of the cutting water and the hardened material. Since it does not depend much on the diameter or the like, the present invention can be used ignoring the influence of the reaction material.
Further, the present invention can be applied not only to a columnar shape but also to a fan-shaped columnar improved body formed by, for example, rotating an injection rod forward and backward. In this case, the forward / reverse rotation angle is added as a new factor, but the correlation may be obtained by using the cutting diameter and the improved diameter as the radius, and the knowledge of the present invention can be basically applied.

It is a schematic diagram of the injection rod used in the present invention. It is a longitudinal cross-sectional view of the injection rod tip. It is the schematic which shows the construction procedure of this invention. It is a figure which shows the correlation with cutting ability pwxqw and the cutting diameter (phi) c of a ground. It is a figure which shows the correlation with improvement body formation capability psxQs and the diameter (phi) of an improvement body. It is a figure which shows the correlation with the injection pressure pw of cutting water, and the discharge amount qw per unit time of cutting water. It is a figure which shows the correlation with the injection pressure ps of a hardening material, and the discharge amount qs per unit time of a hardening material, (a) is the case where the pulling-up speed of an injection rod is 10 minutes / m, (b) is an injection rod. This is the case where the pulling speed of 15 minutes / m. It is a figure which shows the correlation of the injection pressure pw of cutting water, and the cutting water injection | pouring rate (alpha) w, and the correlation of the injection pressure ps of hardening material, and hardening | curing material injection | pouring rate (alpha) s.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Injection rod 2 Upper injection hole 2a First injection hole 2b Second injection hole 3 Lower injection hole 4 Outer pipe 5 Middle pipe 6 Inner pipe 7 First flow path 8 Second flow path 9 Third flow path 10 Triple pipe swivel 11 Boring Machine 12 Casing tube 13 Crane 14 Improved body 15 Column machine G Ground

Claims (2)

Inserting an injection rod with an injection hole at the tip into the ground, and lifting the injection rod while rotating it, injecting a hardener from the injection hole to create a columnar improvement in the ground In the construction method,
From the correlation between the improved body formation ability ps × Qs expressed by the product of the injection pressure ps of the hardened material and the injection amount Qs per unit depth of the hardened material and the diameter φ of the improved body, In addition to the diameter φ, by setting either the injection pressure ps of the curing material or the injection amount Qs per unit depth of the curing material, the injection pressure ps of the curing material that has not been set or the curing Determine the injection quantity Qs per unit depth of the material,
A ground improvement method characterized in that an improved body having a diameter φ is formed using the set or determined injection pressure ps of the hardened material and the injection amount Qs per unit depth of the hardened material. When an injection rod having two upper and lower injection holes at the tip is inserted into the ground and pulled up while rotating the injection rod, cutting water is injected from the upper injection hole and a hardening material is injected from the lower injection hole. In the ground improvement method to create a columnar improvement body in the ground,
From the correlation between the cutting ability pw × qw expressed by the product of the cutting water injection pressure pw and the discharge amount qw per unit time of the cutting water and the cutting diameter φc of the ground, in addition to the cutting diameter φc, By setting either one of the cutting water injection pressure pw or the discharge amount qw per unit time of the cutting water, the cutting water injection pressure pw or the cutting water discharge per unit time that is not set is set. Determine the quantity qw,
From the correlation between the improved body formation ability ps × Qs expressed by the product of the injection pressure ps of the hardened material and the injection amount Qs per unit depth of the hardened material and the diameter φ of the improved body, In addition to the diameter φ, by setting either the injection pressure ps of the curing material or the injection amount Qs per unit depth of the curing material, the injection pressure ps of the curing material that has not been set or the curing Determine the injection quantity Qs per unit depth of the material,
The cutting diameter φc, the cutting water injection pressure pw, the discharge amount qw per unit time of the cutting water, the injection pressure ps of the hardening material, and the injection per unit depth of the hardening material are set or determined. A ground improvement method characterized in that an improved body having a diameter φ is created using the amount Qs.

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