JP2020105289A - Manufacturing system of soil improvement material and manufacturing method of soil improvement material - Google Patents

Abstract

To correspond to errors such as concentration of solution to blend, and to prepare a soil improvement material at a time in large quantities by using an agitation tank.SOLUTION: A manufacturing system includes: a mixed liquid agitation tank 3 preparing mixed liquid by agitating A liquid containing colloidal silica and acid, and B liquid containing silicate; theory pH calculation means 42 calculating theory pH value of the mixed liquid based on the amount of the A liquid supplied to the mixed liquid agitation tank 3, the amount of the B liquid supplied to the mixed liquid agitation tank 3, and the pH value of the A liquid and the pH value of the B liquid; and addition amount calculation means 43 calculating an addition amount of the B liquid to add to the mixed liquid agitation tank 3 based on a difference between the actual pH value and the theory pH value of the mixed liquid.SELECTED DRAWING: Figure 1

Description

The present invention relates to a ground improvement material manufacturing system and a ground improvement material manufacturing method.

As a method of soil improvement for preventing soil collapse due to soil excavation, a method of solidifying soil particles with a chemical solution is known. The chemical liquid used in such a construction method is required to have a function of penetrating into the space between soil particles in a liquid state and then gelling. Therefore, a technique is used in which two types of chemical liquids are prepared, and the two are mixed to cause gelation after a certain period of time from the mixing.

In Patent Document 1, based on a detected mass detected by a mass flow meter provided in a supply pipe, the supply pump is suddenly stopped in anticipation of the excess mass of the stock solution, and a predetermined mass of the stock solution is supplied to the aqueous solution tank. A mixing system for ground improvement chemicals is disclosed.

In Patent Document 2, in a liquid production method of supplying a water glass aqueous solution to each of the first to third mixers in which a sulfuric acid solution continuously flows to obtain a mixed liquid, water glass is supplied to the third mixer. A continuous production apparatus for a water glass-based injecting material has been disclosed in which the pH of the mixed liquid is measured and the amount of water glass supplied to the third mixer is finely adjusted based on the pH.

JP, 2005-143449, A Japanese Utility Model Publication No. 61-183942

However, the error that can be dealt with by the method of Patent Document 1 is only the error of the liquid feed amount, and if the concentration, pH, etc. of the solution to be mixed are different from those expected, the ground improvement material with the desired function cannot be obtained. .. In the method of Patent Document 2, it is not clarified how to determine the supply amount of water glass from the measured pH. Further, in the method of Patent Document 2, when the supply flow rate of the aqueous solution of water glass with respect to the acidic solution is increased, the mixed solution is instantly gelled, so that it is difficult to increase the amount of solution produced per hour.

From the above, it is an object of the present invention to be able to cope with errors such as the concentration of the solution to be mixed, and to enable the production of a large amount of ground improvement material at one time using a stirring tank.

In order to solve the above-mentioned problems, a manufacturing method for a soil improvement material according to the present invention is a mixed solution for producing a mixed solution by stirring an A solution containing colloidal silica and an acid and a B solution containing a silicate. Based on a stirring tank and the amount of the liquid A supplied to the mixed liquid stirring tank, the amount of the liquid B supplied to the mixed liquid stirring tank, the pH value of the liquid A and the pH value of the liquid B. A theoretical pH calculating means for calculating a theoretical pH value of the mixed solution, and an additional amount of the B solution to be added to the mixed solution stirring tank based on a difference between an actually measured pH value of the mixed solution and the theoretical pH value. And an additional amount calculating means for calculating

The method for producing a ground improvement material according to the present invention comprises a primary stirring step of stirring a solution A containing colloidal silica and an acid and a solution B containing a silicate to prepare a primary mixed solution, and Based on the amount of the solution A supplied in the primary stirring step, the amount of the solution B supplied in the primary stirring step, the pH value of the solution A and the pH value of the solution B, the primary mixing A first theoretical pH calculation step of calculating a theoretical pH value of the liquid, and a primary calculation of a primary additional amount of the liquid B based on the difference between the measured pH value of the primary mixed liquid and the theoretical pH value. An additional amount calculation step and a secondary stirring step of supplying the primary additional amount of the solution B to the primary mixed solution and stirring to form a secondary mixed solution are included.
According to such a soil improvement material manufacturing system or a soil improvement material manufacturing method, even if the concentration of the solution A or the solution B has an unexpected value, the mixed solution of the final product is obtained. By adjusting the pH to an expected value, it is possible to obtain a ground improvement material with the intended performance.

Furthermore, the manufacturing system for a soil improvement material according to the present invention, based on the difference between the measured pH value and the theoretical pH value, an additional speed for adding the solution B to the mixed solution stirring tank is calculated. It is preferable to include a speed calculation means.
In addition, the method for producing a soil improvement material according to the present invention has an additional feature of calculating an additional speed when adding the solution B to the primary mixed solution based on the difference between the measured pH value and the theoretical pH value. It is preferable to include a speed calculation step.
According to such a soil improvement material manufacturing system or the soil improvement material manufacturing method, the error of the pH of the soil improvement material is reduced by controlling the speed (supply amount per unit time) of the liquid B to be added. be able to.

Furthermore, the method for manufacturing a soil improvement material according to the present invention is the amount of the primary mixed solution, the measured pH value of the primary mixed solution, the pH of the B solution, and the additional amount of the B solution in the secondary stirring step. Based on the second theoretical pH calculation step of calculating the theoretical pH value of the secondary mixed solution, and the difference between the measured pH value of the secondary mixed solution and the theoretical pH value of the secondary mixed solution, A secondary additional amount calculating step of calculating a secondary additional amount of the liquid B to be further added to the secondary mixed liquid, and supplying and stirring the secondary additional amount of the liquid B to the secondary mixed liquid. It is preferable to include a third agitation step of preparing a third mixed solution.
According to such a method for manufacturing a soil improvement material, the accuracy of pH adjustment can be further improved by adding the liquid B in a plurality of stages.

The soil improvement material manufacturing system and method according to the present invention can cope with errors such as the concentration of the solution to be mixed, and can produce a large amount of soil improvement material at one time using a stirring tank. To

It is a schematic diagram of a soil improvement material manufacturing system. It is a flow of the manufacturing method of the ground improvement material. It is a graph of the time-dependent change of the liquid amount and pH in a mixed liquid stirring tank.

Hereinafter, modes for carrying out the present invention will be described in detail with reference to the drawings as appropriate. The drawings are merely schematic representations so that the present invention can be fully understood. Therefore, the present invention is not limited to the illustrated examples. In each drawing, common or similar components are designated by the same reference numerals, and duplicate description thereof will be omitted.

[Manufacturing system]
FIG. 1 shows a schematic diagram of a ground improvement material manufacturing system S of the present embodiment.
The ground improvement material manufacturing system S of the present embodiment includes an A liquid preparation device 1, a B liquid preparation device 2, a mixed liquid stirring tank 3, and a control means 4, and mixes the A liquid and the B liquid. A ground improvement material is manufactured by supplying and stirring to the liquid stirring tank 3. The liquid A contains colloidal silica, an acid, and water. The acid is not particularly limited, but sulfuric acid or the like can be used. The liquid B contains silicate and water, and the silicate is not particularly limited, but sodium silicate or the like can be used. Sodium silicate is not particularly limited, but one having a low sodium content is preferable from the viewpoint of suppressing gel deterioration due to leaching of silica. By adding the weakly alkaline solution B to the strong acid solution A, the weak acid is liberated, and the mixed solution can be gelated by the precipitation of silicic acid. Further, since the liquid A contains colloidal silica, it is possible to prevent silica from leaching from the gel after the soil particles are solidified by the gel.

The liquid B is supplied in plural times. Then, based on the difference between the pH value theoretically assumed for the mixed solution of A solution and B solution and the measured pH value, the amount of B solution to be additionally supplied is adjusted to improve the ground for the target pH value. Get the material.
The A liquid preparation apparatus 1 includes an A liquid stirring tank 11 and an A liquid storage tank 12. To the A liquid stirring tank 11, colloidal silica and an acid (a constituent material of the A liquid) are supplied from the constituent material tanks 1A to 1C via a liquid feed pump (not shown). Then, the colloidal silica and the acid are stirred in the A solution stirring tank 11 to prepare the A solution, and the prepared A solution is stored in the A solution storage tank 12. The A liquid stirring tank 11 is equipped with a stirring blade driven by a motor 110 to stir the constituent materials of the A liquid. The A liquid storage tank 12 includes a pH meter 120 that measures the pH value of the stored A liquid.

The B liquid preparation apparatus 2 includes a B liquid stirring tank 21 and a B liquid storage tank 22. The B liquid stirring tank 21 is supplied with silicate and water (a constituent material of the B liquid) from the constituent material tanks 2A and 2B via a liquid feed pump (not shown). Then, the B solution is prepared by stirring the silicate and the water in the B solution stirring tank 21, and the prepared B solution is stored in the B solution storage tank 22. The B liquid stirring tank 21 is equipped with a stirring blade driven by a motor 210 to stir the constituent materials of the B liquid. The B liquid storage tank 22 includes a pH meter 220 that measures the pH of the stored B liquid.

The A liquid preparation apparatus 1 is connected to the mixed liquid stirring tank 3 via the A liquid supply path 100. The A liquid produced by the A liquid producing apparatus 1 is supplied to the mixed liquid stirring tank 3. The A liquid supply path 100 includes a liquid feed pump 101 and a flow meter 102. The flow meter 102 measures the flow rate of the A liquid flowing through the A liquid supply path 100, and the liquid feed pump 101 can increase or decrease the flow rate of the A liquid.

The B liquid producing apparatus 2 is connected to the mixed liquid stirring tank 3 via the B liquid supply path 200. The B liquid produced by the B liquid producing device 2 is supplied to the mixed liquid stirring tank 3. The B liquid supply path 200 includes a liquid feed pump 201 and a flow meter 202. The flow meter 202 can measure the flow rate of the B liquid, and the liquid feed pump 201 can increase or decrease the flow rate of the B liquid. The B liquid supply path 200 is branched into a plurality of paths, and a liquid sending pump 201 and a flow meter 202 are provided in each path. In the present embodiment, three liquid feed pumps 201 and two liquid feed pumps 201, six flow meters 202 in total, are provided. By providing a plurality of paths in this way, compared to the case of supplying from one thick supply path, the supply of solution B can be dispersed, and the risk of rapid gelation of the mixed solution mixed solution is reduced. Can be made.

The mixed solution stirring tank 3 is equipped with stirring blades driven by a motor 310, and stirs the A solution supplied from the A solution supply path 100 and the B solution supplied from the B solution supply path 200 to form a mixed solution. Make a liquid. The number of stirring blades is not particularly limited, but the mixed solution stirring tank 3 has a larger capacity than the A solution stirring tank 11 and the B solution stirring tank 21, so that more stirring blades than the A solution stirring tank 11 and the like should be provided. Is preferable from the viewpoint of stirring efficiency. The mixed solution stirring tank 3 also includes a pH meter 320 that measures the pH of the mixed solution.

The control unit 4 includes a measured value acquisition unit 41, a theoretical pH calculation unit 42, an additional amount calculation unit 43, and a supply instruction unit 44, and supplies the liquid A and the liquid B to the mixed liquid stirring tank 3. Control the amount.
The measurement value acquisition means 41 includes a pH value of the solution A measured by the pH meter 120, a pH value of the solution B measured by the pH meter 220, and a pH value of the mixed solution measured by the pH meter 320 (hereinafter, “measured pH value”). That is, the flow rate of the A solution measured by the flow meter 102 and the flow rate of the B solution measured by the flow meter 202 are received and acquired as the flow indicated by the dotted line in FIG. 1 and transmitted to the theoretical pH calculation means 42. ..
The theoretical pH calculating means 42 calculates the supply amounts of the A liquid and the B liquid supplied to the mixed liquid stirring tank 3 from the flow rates of the A liquid and the B liquid per unit time and the time required for the supply. Then, the theoretical pH value of the mixed liquid is calculated based on the supply amount of the A liquid, the pH value of the A liquid, the supply amount of the B liquid, and the pH value of the B liquid, and the calculated theoretical pH value is transmitted to the additional amount calculating means 43. The process of calculating the theoretical pH value of the mixed liquid and transmitting it to the additional amount calculating means 43 in this way is performed twice or more during the supply of the liquid B.

The additional amount calculation means 43 calculates the amount of the solution B to be added to the mixed solution based on the difference between the measured pH value and the theoretical pH value of the mixed solution, and sends it to the supply instructing means 44.
Specifically, it is performed as follows. That is, as described above, the theoretical pH is transmitted to the additional amount calculating means 43 a plurality of times during the supply of the liquid B. The additional amount calculation means 43 respectively measures the measured pH of the mixed liquid corresponding to each theoretical pH. Then, based on the data of a plurality of obtained “pairs of measured pH and theoretical pH”, the corrected pH value of solution A and the corrected pH value of solution B in which the absolute value of the difference between the measured pH and the theoretical pH is minimum. And calculate. In order to specify the two variables of the corrected pH value of the solution A and the corrected pH value of the solution B, it is necessary to measure the above “set of theoretical pH and measured pH value” multiple times. According to such a method, the calculation accuracy of the additional amount of the B solution is improved by calculating the corrected pH values of both the A solution and the B solution based on the plurality of measurement data, and the ground having the pH value as planned is obtained. An improved material can be prepared.
Required to obtain the corrected pH value of the mixed solution from the corrected pH value of solution A, the supply amount of solution A, the corrected pH value of solution B, and the supplied amount of solution B, and to reach the planned pH value from this corrected pH value. Calculate the amount of liquid B. This amount of the B liquid is the additional amount of the B liquid. By calculating the additional amount of the B liquid in this way, not only the measurement error of the pH value of the A liquid and the B liquid but also the measurement error of the supply amount of the A liquid and the B liquid supply amount can be dealt with.

The method of calculating the amount of the liquid B to be added to the mixed liquid is not limited to the above, and examples thereof include the following methods. In the above method, the additional amount calculation means 43 calculates the corrected pH values for both the A solution and the B solution, but either one of the pH values of the A solution and the B solution measured by the pH meter 120 and the pH meter 220 is correct. It is also possible to calculate only the corrected pH value of the other liquid and determine the additional amount of the liquid B. According to such a method, the additional amount of the B liquid can be calculated more easily.
Further, the pH values of the A liquid and the B liquid are not measured in the A liquid storage tank 12 and the B liquid storage tank 22, but a temporary value is set, and the theoretical pH of the mixed liquid is calculated based on the temporary value. , The additional amount of the B liquid may be calculated. According to such a method, the pH meters 120 and 220 can be removed from the A liquid storage tank 12 and the B liquid storage tank 22 of the ground improvement material manufacturing system S.

In addition, it is preferable that the additional amount calculation means 43 calculates not only the amount of the B liquid to be added, but also the additional speed (the additional amount per unit time). Specifically, as the pH value of the mixed solution increases and approaches the planned pH of the ground improvement material, the feed rate of the solution B is reduced, so that an error in pH adjustment can be suppressed. Therefore, the additional amount calculation means 43 increases or decreases the additional speed of the liquid B from the planned speed based on the corrected pH of the mixed liquid.
The supply instructing unit 44 drives the liquid feed pump 201, monitors the amount of the B liquid flowing through the B liquid supply path 200 with the flow meter 202, and determines that the additional amount of the B liquid is the additional amount calculated by the additional amount calculating unit 43. The liquid feed pump 201 is controlled so that

[Production method]
FIG. 2 shows a flow of the method for manufacturing the ground improvement material of the present embodiment. In the method for manufacturing a ground improvement material of the present embodiment, steps S101 to S111 are executed.
In step S101, water and an acid are supplied to the A liquid stirring tank 11 and stirred, and colloidal silica is further supplied to the A liquid stirring tank 11 to stir the liquid A to prepare the liquid A storage tank. Store in 12. When a strongly acidic reaction material is supplied to colloidal silica made of weak alkali, a partial neutral region is generated, and the gelation reaction proceeds in a part of solution A. Supplied by.
In step S102, the pH value of the liquid A in the liquid A storage tank 12 is measured by the pH meter 120 provided in the liquid A storage tank 12. The pH of the liquid A may be acquired by the pH meter 320 provided in the mixed liquid stirring tank 3 when the liquid A is sent to the mixed liquid stirring tank 3. However, when the soil improvement material is repeatedly produced a plurality of times, it is considered that the mixed liquid remains in the mixed liquid stirring tank 3, so the pH of the A liquid is measured by the pH meter 120 of the A liquid storage tank 12. It is preferable to do so because the measurement can be performed more accurately.

In step S<b>103, water and silicate acid are supplied to the B liquid stirring tank 21 and stirred, whereby the liquid B is prepared and stored in the liquid B storage tank 22.
In step S104, the pH of the B liquid in the B liquid storage tank 22 is measured.
In step S105, the primary supply amount of the B liquid is smaller than the planned total supply amount of the B liquid. In step S105, the liquid A is supplied to the mixed liquid stirring tank 3, and then the liquid B is primarily supplied to perform primary stirring to form a primary mixed liquid (mixed liquid). In addition, if the supply order of the liquid A and the liquid B is reversed, that is, if the liquid B is supplied first, the liquid A of the strong acid liquid is added to the liquid B of weak alkaline. At the time when a fixed amount was added, the entire mixed solution became neutral and instantly gelled.
In step S106, the theoretical pH value of the primary mixed solution is calculated over a plurality of times based on the supply amount of the A liquid, the pH value of the A liquid, the supply amount of the B liquid, and the pH value of the B liquid.

In step S107, the measured pH corresponding to each theoretical pH calculated in step S106 is measured, the corrected pH of the primary mixed solution that minimizes the difference between each measured pH value and each theoretical pH value is calculated, and the corrected pH is calculated. Based on the above, the amount of liquid B to be added (first additional amount) is calculated. In addition, in step 107, it is preferable to calculate the additional speed of the solution B (first additional speed) based on the difference between the measured pH value and the theoretical pH value of the primary mixed solution.
In step S108, while monitoring the amount of the B liquid flowing through the B liquid supply path 200 with the flow meter 202, the liquid feed pump 201 agitates the mixed liquid so that the additional amount of the B liquid becomes the primary additional amount. Supply to tank 3. When the primary additional speed is calculated in step 107, the liquid B is added while controlling the additional speed of the liquid B to be the primary additional speed. The mixed liquid stirring tank 3 secondarily stirs the primary mixed liquid and the added liquid B, and secondarily stirs to form a secondary mixed liquid (mixed liquid).

In step S109, the theoretical pH value of the secondary mixed solution is calculated based on the amount of the primary mixed solution, the measured pH value of the primary mixed solution, the pH of solution B, and the primary additional amount of solution B.
In step S110, the secondary addition amount of the solution B further added to the secondary mixed solution is calculated based on the difference between the actually measured pH value and the theoretical pH value of the secondary mixed solution. In addition, in step S110, it is preferable to calculate the additional speed (secondary additional speed) of the liquid B based on the difference between the measured pH value and the theoretical pH value of the secondary mixed solution.

In step S111, while monitoring the amount of the B liquid flowing through the B liquid supply path 200 with the flow meter 202, the liquid feed pump 201 agitates the mixed liquid so that the additional amount of the B liquid becomes the secondary additional amount. Supply to tank 3. In addition, when the secondary additional speed is calculated in step S110, the liquid B is added while controlling the additional speed of the liquid B to be the secondary additional speed.
The mixed liquid stirring tank 3 stirs the secondary mixed liquid and the supplied secondary additional liquid B to form a tertiary mixed liquid.
In addition, the soil improvement material manufacturing system S may supply the liquid B in two times to produce the soil improvement material without performing the steps S109 to S111. If it is supplied in two batches, the pH of the ground improvement material can be adjusted more easily, and if it is supplied in three or more batches, the ground improvement material with less pH error can be prepared.

FIG. 3 is a graph showing the change over time in the relationship between the liquid amount and the pH in the mixed liquid stirring tank 3, and the adjustment of the additional amount of liquid B and the additional speed will be described. The horizontal axis represents elapsed time, the left axis represents the ratio of the amount of the mixed liquid to the volume of the mixed liquid stirring tank 3, and the right axis represents the pH of the mixed liquid in the mixed liquid stirring tank 3.
The solid line shows the amount of the mixed solution, and the alternate long and short dash line shows the planned total supply of solutions A and B. The broken line indicates the measured pH of the mixed solution, and the two-dot chain line indicates the planned pH (theoretical pH) of the mixed solution calculated by the theoretical pH calculating means 42.

Until time t1, only the liquid A is supplied to the mixed liquid stirring tank 3. At time t1, the supply of the planned amount of liquid A is completed and the supply of liquid A is stopped. After that, the primary supply of the liquid B is started from time t1. The liquid B is supplied at a lower speed than the liquid A at a supply speed in order to prevent the gelation of the mixed liquid and the like.
At time t2, the primary supply of the planned amount of liquid B is completed. When the measured pH of the primary mixed solution and the theoretical pH are compared at time t2, the measured pH of the primary mixed solution is higher than the planned pH. That is, the influence of the liquid B on the primary mixed liquid is larger than planned.
Therefore, the additional amount calculating means 43 reduces the additional amount of the liquid B as compared with the plan. Moreover, since the pH of the primary mixed solution is too higher than planned, the additional speed of solution B is also set to be lower than the planned speed. From time t2, the supply instructing means 44 drives the liquid feed pump 201 to start adding the liquid B. The supply instructing means 44 monitors the B liquid flowing through the B liquid supply path 200 with the flow meter 202, and controls the liquid feed pump 201 so that the additional speed and the additional amount calculated by the additional amount calculating means 43 are obtained. As described above, by adjusting the additional speed and the additional amount of the solution B, the theoretical pH and the measured pH of the primary mixed solution match at one point between time t2 and time t3, and at the time t3, the A soil improvement material having a consistent pH value is obtained.

According to the soil improvement material manufacturing system S and the method for manufacturing the soil improvement material of the present embodiment, differences in the pH and the concentration of the constituent material of the soil improvement material for each lot, the measurement error of the constituent material, the A liquid and the B liquid Even if there is an error in the measurement of the amount supplied to the mixed liquid stirring tank 3, a large amount of the ground improvement material having the planned pH value can be prepared in the stirring tank.

Although the embodiment according to the present invention has been described above, the present invention is not limited to the above-described embodiment, and each component can be appropriately added or changed without departing from the spirit of the present invention. For example, the ground improvement material manufacturing system S may be provided with a circulation mixing path for circulating the mixed liquid between the liquid feed pump 101 and the mixed liquid stirring tank 3 in addition to the configuration of the above-described embodiment. This circulation mixing path is provided with one or more static mixers, and the liquid circulating inside can be agitated by the static mixers.
The soil improvement material manufacturing system S switches the route through which the liquid feed pump 101 feeds the liquid from the A liquid feed route 100 to the circulation mixing route after completing the supply of the liquid A to the mixed liquid stirring tank 3. The mixed solution in the stirring tank 3 is circulated in the circulation mixing path. With such a configuration, the ground improvement material manufacturing system S can stir the mixed liquid with the static mixer in the circulation mixing path. The mixed solution is stirred by both the stirring blades of the mixed solution stirring tank 3 and the static mixer in the circulation mixing path, and the liquid production capacity of the ground improvement material manufacturing system S can be improved.

S Ground improvement material manufacturing system 1 A liquid preparation device 11 A liquid stirring tank 12 A liquid storage tank 100 A liquid supply path 101, 201 Liquid feed pump 102, 202 Flow meter 120, 220, 320 pH meter 2 B liquid preparation liquid Device 21 B liquid stirring tank 22 B liquid storage tank 200 B liquid supply path 3 Mixed liquid stirring tank 4 Control means 41 Measured value acquisition means 42 Theoretical pH calculation means 43 Additional amount calculation means 44 Supply instruction means?

Claims (5)

A mixed solution stirring tank for preparing a mixed solution by stirring solution A containing colloidal silica and acid and solution B containing silicate;
Based on the amount of the liquid A supplied to the mixed liquid stirring tank, the amount of the liquid B supplied to the mixed liquid stirring tank, the pH value of the liquid A and the pH value of the liquid B, the mixed liquid A theoretical pH calculating means for calculating the theoretical pH value of
An additional amount calculating means for calculating an additional amount of the liquid B to be added to the mixed liquid stirring tank based on a difference between an actually measured pH value of the mixed liquid and the theoretical pH value. Improved material manufacturing system. The additional speed calculation means for calculating an additional speed when the liquid B is added to the mixed liquid stirring tank is provided based on a difference between the measured pH value and the theoretical pH value. The ground improvement material manufacturing system described in. A primary stirring step of stirring a liquid A containing colloidal silica and an acid and a liquid B containing a silicate to form a primary mixed liquid;
Based on the amount of the solution A supplied in the primary stirring step, the amount of the solution B supplied in the primary stirring step, the pH value of the solution A and the pH value of the solution B, the primary A first theoretical pH calculating step of calculating a theoretical pH value of the mixed solution;
A primary additional amount calculating step of calculating a primary additional amount of the liquid B based on the difference between the measured pH value of the primary mixed liquid and the theoretical pH value;
A secondary stirring step of supplying the primary additional amount of the solution B to the primary mixed solution and stirring the solution to form a secondary mixed solution. 4. An additional speed calculation step of calculating an additional speed when adding the solution B to the primary mixed solution based on a difference between the measured pH value and the theoretical pH value. A method for manufacturing the ground improvement material according to. The theoretical pH value of the secondary mixed solution is calculated based on the amount of the primary mixed solution, the measured pH value of the primary mixed solution, the pH of the B solution, and the additional amount of the B solution in the secondary stirring step. A second theoretical pH calculating step of calculating,
Secondary addition for calculating a secondary additional amount of the solution B to be further added to the secondary mixed solution based on a difference between an actually measured pH value of the secondary mixed solution and a theoretical pH value of the secondary mixed solution. Quantity calculation process,
4. A third stirring step of supplying the second additional amount of the solution B to the second mixed solution and stirring the mixture to form a third mixed solution, the ground according to claim 3. Method for manufacturing improved material.

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