JP7125073B2 - Method for producing solidified soil - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing solidified soil by adding at least a solidifying material to a soil material having a known water content. In the present application, soil material means a mixture of soil particles and water, and solidifying material means a solid that does not contain water. The solidifying material is provided in powder form, for example, with a particle size of less than 0.1 millimeters.

Effective use of dredged soil is required due to the lack of disposal sites. One of the major methods of disposal of dredged soil is to mix the dredged soil with a solidification material and use it as a landfill material, which has already been used for construction work in various places. The uniaxial compressive strength of the solidified soil in this case is about 0.1 to 0.2 meganewtons per square meter [MN/m ² ] as the design standard strength, and the indoor compound strength considering the safety factor is 0.2 to 0.5 meganewtons per square meter [MN/m ² ].

For further expansion of applications, it is also being considered to manufacture high-strength solidified soil blocks with a uniaxial compressive strength of 10 meganewtons per square meter [MN/m ² ] or more using dredged soil. This high-strength solidified soil can be used as a substitute for gravel and natural stone.

Solidified soil with a uniaxial compressive strength of about 10 meganewtons per square meter [MN/m ² ] or more is classified as semi-hard stone in terms of strength according to Japanese Industrial Standards (JIS) A5003:1995 "Stone material", and seawater It has the advantage of being expected to be stable for a long period of time because it hardly deteriorates due to elution of calcium even when used inside.

Non-Patent Document 1 describes a method using a high-pressure filter press as a method for producing solidified soil having a uniaxial compressive strength of 10 meganewtons per square meter [MN/m ² ] or more. In this method, solidifying material is mixed with dredged soil adjusted to a high moisture content, and then dehydrated at a high pressure of 4 meganewtons per square meter [MN/m ² ] to produce high-strength solidified soil.

Yuka Yamashita, Zen Kung Ki, Chen Guangqi, Kiyonobu Kasama: Homogeneity and Strength Characteristics of Large Dredged Soil Blocks by Dehydration and Solidification Treatment, Journal of Japan Society of Civil Engineers, Ser. B3 (Marine Development), Vol.67, No.2, pp.440-444, 2011.

However, the method described in Non-Patent Document 1 has a problem that the cost is high and it is not suitable for mass production.

One of the objects of the present invention is to produce solidified soil having a uniaxial compressive strength of 10 meganewtons per square meter or more and the fluidity required during production at a lower cost than a method using a high-pressure filter press. is.

A method for producing solidified soil according to claim 1 of the present invention comprises the steps of preparing a soil material having a known water content, adding at least a solidifying material to the soil material, and stirring with a batch-type stirrer, a step of producing a solidified soil having a predetermined ratio of water to a solidifying material; a step of determining whether the fluidity of the solidified soil satisfies a predetermined condition; a step of adding a solidifying material and water to the solidified soil so that the ratio maintains the value and stirring with the stirrer until it is determined that the condition is satisfied; and and a total amount of solidifying material added to said soil material and a total amount of water until said fluidity is determined to satisfy said condition. adding a solidification material in an amount corresponding to the specified total amount of the solidification material to the second soil material, and adding water in an amount equivalent to half or less of the specified total amount of water. After the first stirring step of adding and stirring with the stirrer, and stirring by the first stirring step, the remaining water is added so that the cumulative amount of water added corresponds to the total amount of water. a second stirring step of adding to the second soil material and stirring with the stirrer .

A method for producing solidified soil according to claim 2 of the present invention is the method for producing solidified soil according to claim 1, wherein the step of determining whether the fluidity of the solidified soil satisfies the condition is is characterized in that the yield of the solidified soil agitated by the agitator is used.

A method for producing solidified soil according to claim 3 of the present invention is the method for producing solidified soil according to claim 1 or 2, wherein it is determined whether or not fluidity of the solidified soil satisfies the condition. The process is characterized by using the results of at least one or more of the vane shear test, needle penetration test, and cone penetration test of the solidified soil .

According to the present invention, it is possible to produce solidified soil having a uniaxial compressive strength of 10 meganewtons per square meter or more and the fluidity required at the time of production at a lower cost than a method using a high-pressure filter press.

The figure which shows the example of the manufacturing method of solidified soil. The figure which shows the unconfined compressive strength test result shown in Table 2. The figure which shows the needle penetration test result shown in Table 3. The figure which shows the relationship between the penetration resistance value and shear strength which are shown in Table 4. FIG. 10 is a diagram showing a method for manufacturing solidified soil on site in Modification 1; FIG. 10 is a diagram showing needle penetration test results of the mixed material in Modification 1; 4 is a diagram showing the air content and uniaxial compressive strength of the mixed material in Modification 1. FIG.

<Method for producing solidified soil>
FIG. 1 is a diagram showing an example of a method for producing solidified soil. A manufacturer of solidified soil first selects a raw material of soil material such as dredged soil to be used for solidified soil (referred to as raw material soil), and measures the water content of the raw material soil (step S101). Since the raw material soil is composed of water and soil particles, the water content ratio of the raw material soil means the water/soil particle weight ratio of the raw material soil.

Then, the manufacturer adds different amounts of the solidifying material and water to the raw material soil, stirs the mixture, and cures the mixture for a predetermined period to prepare a plurality of samples (step S102). These samples are based on the mixing ratio of water to soil particles in the raw material soil (referred to as "water/soil particle weight ratio") and the mixing ratio of water to the added solidifying material (referred to as "water/solidifying material weight ratio"). , are different samples. Samples are prepared, for example, after curing for 28 days. In addition, if the sample to be created contains a material with a water/soil particle weight ratio lower than the water content ratio of the raw material soil, the manufacturer should dry the raw material soil to reduce the water content ratio of the soil material ( dry treated soil) may be used.

The manufacturer, for example, JIS A1108: 2006 "Concrete compression strength test method" and JIS A1216: 2009 "Soil uniaxial compression test method" for a plurality of samples uniaxially Each compressive strength is measured (step S103).

Then, the manufacturer determines the water/solidifying material weight ratio that satisfies the standard for unconfined compressive strength in all the water/soil particle weight ratio ranges (step S104). Here, the defined range is, for example, a range in which the water/soil particle weight ratio is 60% or more. Moreover, the determined standard is, for example, a condition of 10 meganewtons per square meter [MN/m ² ] or more.

The manufacturer sets the water content ratio of the raw material soil measured in step S101 as the initial value of the water/soil particle weight ratio (step S105). That is, the manufacturer prepares raw material soil whose water content is not adjusted as a soil material with a known water content ratio. The manufacturer may dry the raw material soil or add water to the raw material soil to prepare a soil material in which the water/soil particle weight ratio is adjusted to a predetermined initial value. Also in this case, the water/soil particle weight ratio after drying or adding water is adjusted to the initial value, so the water content ratio of the prepared soil material is known.

The manufacturer adds a solidification material (or a solidification material and water) to the prepared soil material and stirs (step S106). This addition is performed so that the water/solidifying material weight ratio after the addition and stirring becomes the water/solidifying material weight ratio determined in step S104. Moreover, this stirring is performed by a batch-type stirrer. As a result, solidified soil having a predetermined ratio of water and solidifying material is produced. In step S106, the manufacturer may add only the solidifying material, or may add the solidifying material and water.

Step S105 is an example of a step of preparing a soil material with a known water content.
In step S106, which follows step S105, at least a solidification material is added to the soil material and stirred by a batch-type stirrer to obtain solidified soil having a predetermined ratio of water to solidification material. It is an example of the manufacturing process.

The manufacturer determines whether or not the fluidity of the solidified soil manufactured in step S106 satisfies the conditions (step S107). For the determination of this fluidity, the yield of the solidified soil when taken out from the stirrer may be used, or the shear strength of the solidified soil or the shear strength of the solidified soil (convertible ) index may be used.

The shear strength of the solidified soil is obtained, for example, from the result of a vane shear test. The vane shear test is, for example, the vane shear test defined in the Japanese Geotechnical Society standard JGS1411-2012 "In-situ vane shear test method".

Further, for example, test results such as a needle penetration test and a cone penetration test can be converted into shear strength. The needle penetration test is, for example, a penetration test defined in JIS A1147:2007 "Concrete setting time test method". The cone penetration test is, for example, JIS A1220 "Dutch type double pipe cone penetration test method", Geotechnical Society standard JGS1431-2003 "Portable cone penetration test method", etc. It is a cone penetration test specified.

The manufacturer should use the results of at least one of the vane shear test, needle penetration test, and cone penetration test for the solidified soil to determine whether the fluidity of the solidified soil satisfies the above conditions. Just do it.

When determining that the fluidity of the solidified soil satisfies the conditions (step S107; YES), the manufacturer ends the process.

On the other hand, when it is determined that the fluidity of the solidified soil does not satisfy the conditions (step S107; NO), the manufacturer repeats step S106. That is, the manufacturer adds and stirs the solidifying material and water so that the water/solidifying material weight ratio after addition and stirring maintains the water/solidifying material weight ratio determined in step S104.

Needless to say, the above-mentioned step S106 can be repeated only before the added solidifying material begins to solidify.

Step S107 is an example of a step of determining whether or not the fluidity of the solidified soil satisfies a predetermined condition.

When the yield of the solidified soil is used to determine the fluidity, step S107 uses the yield of the solidified soil stirred by the stirrer to satisfy the condition that the fluidity of the solidified soil is determined. It is an example of the process of determining whether or not.

Further, when the shear strength of the solidified soil (shear strength or an index that can be converted to the shear strength) is used to determine the fluidity, step S107 uses the shear strength of the solidified soil, etc. This is an example of a process for determining whether or not the fluidity of the solidified soil satisfies a predetermined condition.

Further, in step S106, which is performed after step S107, until it is determined that the fluidity satisfies a predetermined condition, the solidified soil is solidified so that the ratio of water to the solidifying material is maintained at a predetermined value. It is an example of a process of adding materials and water and stirring with a stirrer.

As described above, the water/solidification material weight ratio is determined for producing the solidified soil that satisfies the target value of indoor mixing strength. Then, using the determined water/solidification material weight ratio, the raw material soil is dried or hydrated to prepare a soil material, and at least a solidification material is mixed with the prepared soil material to produce the solidified soil. be done.

<Experimental example>
Below, it demonstrates based on an example of an experiment.

<Characteristics of raw soil>
Table 1 is a table showing the physical properties of the raw material soil used for the solidified soil. In this example, the present inventor used Nagoya Port Marine Clay, which is dredged soil, as raw material soil.

<Formulation of formulation plan>
The present inventor measured the water content ratio of the raw material soil, and changed the amount of solidifying material and water added to this raw material soil (or dry treated soil) to obtain the water/soil particle weight ratio and the water/solidifying material weight. A formulation plan with different ratios was formulated. Then, according to the composition plan, the present inventor added a solidifying material and water to the raw material soil (or dried treated soil), stirred them, and cured them for 28 days to produce 9 types of solidified treated soil, Uniaxial compressive strength was measured for each of them. In this example, blast furnace type B cement manufactured by Taiheiyo Cement Co., Ltd. was used as the solidifying material, and tap water was used as the water.

Table 2 is a table showing the results of a uniaxial compressive strength test of samples (also referred to as samples) manufactured with this formulation scheme. In Table 2, the water/solidifying material weight ratio [-] is represented by "Ww/Wc", and the above water/soil particle weight ratio [%] is represented by "100 x Ww/Ws". In Table 2, the unconfined compressive strength [MN/m ² ] of the 28-day sample is represented by "q _u28 ".

In this formulation, the water/soil particle weight ratios "100×Ww/Ws" are 60%, 80%, and 100%, and the water/solidifying material weight ratios "Ww/Wc" are 1.2, 2.0, 4.0. When the water content ratio of the raw material soil used was measured, the water content ratio was "80%".

Sample numbers "1", "2", and "3" are groups in which the water/solidifying material weight ratio is "1.2". The water/soil particle weight ratio is "60%" for sample number "1", "80%" for sample number "2", and "100%" for sample number "3".

Sample numbers "4", "5", and "6" are groups in which the water/solidifying material weight ratio is "2.0". The respective water/soil particle weight ratios are "60%" for sample number "4", "80%" for sample number "5", and "100%" for sample number "6".

Sample numbers "7", "8" and "9" are all groups with a water/solidifying material weight ratio of "4.0". The water/soil particle weight ratio is "60%" for sample number "7", "80%" for sample number "8", and "100%" for sample number "9".

<Determination of default value>
2 is a diagram showing the results of the uniaxial compressive strength test shown in Table 2. FIG. In FIG. 2, the horizontal axis represents the water/soil particle weight ratio [%] of each group classified by the water/solidifying material weight ratio, and the vertical axis represents the uniaxial compressive strength [MN/m ² ].

The inventor referred to the data shown in Table 2 and FIG. 2 and compared the unconfined compressive strength for each group. As a result, regardless of the water/soil particle weight ratio of "60%", "80%", or "100%", the group with the water/solidifying material weight ratio of "1.2" satisfies the condition of unconfined compressive strength. It was found that only The present inventors have determined the specified value of the water/solidifying material weight ratio to be "1.2". In addition, the condition of the unconfined compressive strength was set to be 10 meganewtons per square meter [MN/m ² ] or more.

In addition, among the groups in which the water/solidifying material weight ratio is "1.2", the sample number "2" in which the water/soil particle weight ratio is "80%" had the highest unconfined compressive strength. The measured value of the water content ratio of the raw material soil is also "80%". Therefore, the present inventor determined the initial value of the water/soil particle weight ratio to be "80%", which is the water content ratio of the raw material soil.

In the above example, the determined range of the water/soil particle weight ratio is set to "60% or more", but for example, the determined range of the water/soil particle weight ratio is set to "80% or more". You may In this case, the group in which the water/solidifying material weight ratio is "2.0" shown in Table 2 and Fig. 2 also satisfies the condition of unconfined compressive strength when the water/soil particle weight ratio is "80% or more". The specified value of the water/solidifying material weight ratio may be determined to be "2.0". That is, depending on how the range of the water/soil particle weight ratio is determined, the prescribed value of the water/solidification material weight ratio may vary.

<Judgment of liquidity>
<First stirring>
The present inventor set the measured water content ratio of the raw material soil of 80% as the initial value of the water/soil particle weight ratio. That is, the present inventor prepared raw material soil whose water content was not adjusted as a "soil material having a known water content".

Subsequently, the present inventor added a solidifying material to the prepared soil material so that the water/solidifying material weight ratio was the specified value of "1.2", and stirred with a batch-type stirrer. As a stirrer, a twin-screw forced kneading mixer manufactured by Kitagawa Iron Works was used. This stirrer is a device that stirs powder and liquid put into a stirring chamber with a rated value of 60 liters for the stirring capacity, which is composed of two blades composed of a spiral ribbon without a shaft. . In addition, the rated value of this stirring capacity is a value determined with allowance for the capacity of this stirrer, and the actual stirring capacity of this stirrer should greatly exceed this rated value. rice field. An opening having a width of 11 centimeters and a length of 65 centimeters is provided in the lower part of the agitator, and the solidified soil after agitation is taken out from this opening. The size and shape of the opening are desirably set so that the solidified soil can be taken out smoothly.

In the first stirring, 60 liters of solidified soil was produced by adding only the solidifying material, that is, blast furnace type B cement, without adding water. As a result, the water/soil particle weight ratio was maintained at the initial value of 80%. The amount of solidification material to be added was determined according to the amount of water contained in the soil material prepared by adjusting the water content ratio, and as a result, the water/solidification material weight ratio of the solidified soil was "1.2". The solidified soil to which only the solidifying material was added was stirred with a stirrer for 3 minutes. The present inventor visually confirmed that the solidified soil in the stirring chamber was uniformly mixed, and then determined whether or not the fluidity of the solidified soil produced satisfies the determined conditions. .

The solidified soil produced by this first stirring could not be taken out from the opening at the bottom of the stirrer. That is, the yield was 0%. In response to the fact that the yield was 0%, the inventor determined that the fluidity did not satisfy the determined conditions, and added a further solidifying material and stirred.

<Second stirring>
In the second stirring, a solidifying material is added to the solidified soil produced by the first stirring, and then water is added in an amount corresponding to the amount of this solidifying material added, making a total of 4 liters. Added. In addition, the order of addition is not limited to that described above in the second and subsequent stirrings. For example, the solidifying material and water may be added at the same time, or a solidifying material slurry obtained by mixing the solidifying material and water in advance may be added. The amounts of the solidifying material and water added were adjusted so that the water/solidifying material weight ratio was the specified value of "1.2".

The solidified soil to which the solidifying material and water were added was stirred for 3 minutes with a stirrer. As a result, the solidified soil after stirring had a water/solidifying material weight ratio of "1.2", which is the specified value, and a water/soil particle weight ratio of "89.1%". The present inventor visually confirmed that the solidified soil in the stirring chamber was uniformly mixed, and then determined whether or not the fluidity of the solidified soil produced satisfies the determined conditions. .

The solidified soil produced by this second agitation could not be taken out from the opening at the bottom of the agitator. In response to this, the inventor determined that the fluidity did not meet the determined conditions, and added a further solidifying material and stirred.

<Third stirring>
In the third stirring, a solidifying material was further added to the solidified soil produced by the second stirring, and then water was added in an amount corresponding to the amount of this solidifying material added, making a total of 4 liters. Added. The amounts of the solidifying material and water added were adjusted so that the water/solidifying material weight ratio was the specified value of "1.2".

The solidified soil to which the solidifying material and water were added was stirred for 3 minutes with a stirrer. As a result, the solidified soil after stirring had a water/solidifying material weight ratio of "1.2", which is the specified value, and a water/soil particle weight ratio of "98.3%". The present inventor visually confirmed that the solidified soil in the stirring chamber was uniformly mixed, and then determined whether or not the fluidity of the solidified soil produced satisfies the determined conditions. .

When the weight of the solidified soil produced by this third stirring was taken out from the opening at the bottom of the agitator, it was 70% of the total amount produced in the agitation chamber at this time. That is, the yield was 70%. In response to this, the inventor determined that the condition for fluidity was satisfied.

<Fourth Stirring>
The present inventor newly prepared raw material soil whose water content was not adjusted as a soil material with a known water content. This water content ratio, that is, the water/soil particle weight ratio is the initial value of 80%. Then, the present inventor added a total of 60 liters of the prepared soil material and the solidification material without removing the solidified soil remaining in the stirring chamber in the third stirring described above, and stirred for 3 minutes with this stirrer. Stirred. The amount of solidification material to be added was determined according to the amount of water contained in the soil material so that the water/solidification material weight ratio of the solidified soil after addition was the specified value of "1.2". As a result, the solidified soil produced by the fourth agitation had a water/solidifying material weight ratio of 1.2, which is the prescribed value.

In the fourth stirring, the present inventor did not judge the fluidity, considering that the yield of the solidified soil was 0% in the first stirring. Then, the inventor further added a solidification material to the solidified soil produced by the fourth agitation, and then added water in an amount corresponding to the amount of the solidification material added. The amounts of the solidifying material and water to be added were the amounts of the above-described second and third additions at once, and a total of 8 liters was added.

<Fifth Stirring>
In the fifth stirring, the solidified soil to which the solidifying material and water were added was stirred for 3 minutes with a stirrer. As a result, the solidified soil after stirring had a water/solidifying material weight ratio of "1.2", which is the specified value, and a water/soil particle weight ratio of "98.3%". The present inventor did not judge the fluidity of the solidified soil obtained for this fifth stirring, and added a solidifying material, and then added an amount of the solidifying material according to the amount of the solidifying material added. Water was added for a total of 4 liters. The amount of the solidifying material to be added was determined so that the water/solidifying material weight ratio of the solidified soil was the specified value of "1.2".

<Sixth Stirring>
In the sixth stirring, the solidified soil to which the solidifying material and water were added was stirred by a stirrer for 3 minutes. As a result, the solidified soil after agitation had a water/solidification material weight ratio of 1.2, which is the specified value, and a water/soil particle weight ratio of 107.4%. The present inventor visually confirmed that the solidified soil in the stirring chamber was uniformly mixed, and then determined whether or not the fluidity of the solidified soil produced satisfies the determined conditions. .

95% of the solidified soil produced by this sixth agitation was taken out from the opening at the bottom of the agitator. That is, the yield was 95%. In response to this, the inventor determined that the condition for fluidity was satisfied.

<Needle penetration test>
Table 3 is a table showing the needle penetration test results of the solidified soil. The present inventor conducted a needle penetration test according to JIS A1147:2007 on each of the first to sixth solidified soils described above.

FIG. 3 is a diagram showing the needle penetration test results shown in Table 3. FIG. In FIG. 3, the water/soil particle weight ratio [%] of the solidified soil shown in Table 3 is plotted on the horizontal axis, and the 5 mm penetration resistance value [kN/m ² ] on the vertical axis. This figure shows that the 5mm penetration resistance decreases as the water/soil particle weight ratio increases. , it was found that the fluidity of the solidified soil increased.

<Vane shear test>
The present inventor conducted a penetration test (needle penetration test) according to JIS A1147:2007 "Concrete setting time test method" for multiple types of soil materials, etc. An in-situ vane shear test (an example of a vane shear test) was conducted in accordance with "Vane Shear Test Method".

Table 4 shows the 5mm penetration resistance value p [kN/m ² ] and the shear strength τ [kN/m ² ] of each sample in correspondence with each other.

FIG. 4 is a diagram showing the relationship between the penetration resistance value shown in Table 4 and the shear strength. In FIG. 4, the 5 mm penetration resistance value p [kN/m ² ] shown in Table 4 is plotted on the horizontal axis, and the shear strength τ [kN/m ² ] on the vertical axis. From this figure, it was found that the shear strength of the soil material is proportional to the power of the penetration resistance value of the soil material. That is, the 5 mm penetration resistance value of the solidified soil can be used as an index of the shear strength of the solidified soil. As the index of the shear strength of the solidified soil, another index that can be converted into the shear strength may be used. Other indicators include, for example, the results of cone penetration tests.

The present inventors performed interpolation calculations by the least squares method or the like for each plot of the 5 mm penetration resistance value p [kN/m ² ] and the shear strength τ [kN/m ² ], and the following equation (1) We obtained an approximation expressed by
τ=0.2143p ^0.8262 (1)
According to the approximation expressed by formula (1), the 5mm penetration resistance value p of sample number 14 described above is 22 [kN/m ² ], so its shear strength τ is 2.76 [kN/m ² ]. It is estimated to be.

<Uniaxial compression strength test>
A uniaxial compressive strength measurement test according to JIS A1108:2006 "Compressive strength test for concrete" was performed on a sample obtained by curing the solidified soil indicated by the above sample number 14 for 28 days. As a result, the uniaxial compressive strength of the solidified soil indicated by sample number 14 on the 28th day of the material age was 16.9 [MN/m ² ], and at 10 meganewtons per square meter [MN/m ² ] there were.

As described above, at least a solidification material is added to a soil material with a known water content ratio, and the mixture is stirred with a batch-type stirrer, and the solidification material and water are added so that the ratio of water and solidification material is maintained at a specified value. By adding and stirring, the solidified soil that has a uniaxial compressive strength of 10 meganewtons per square meter [MN/m2] or more and has the fluidity required during production can be obtained compared to the method using a high-pressure filter press. It turned out that it becomes possible to manufacture at low cost.

<Supplement>
The following points are supplementary explanations of the embodiments. That is, the process from step S101 to step S105 shown in FIG. 1 is an example of a process of preparing a soil material with a known water content. In addition, the process of step S106 performed for the first time is an example of the first mixing process in which at least the solidifying material is added to the soil material and stirred by a batch-type stirrer to obtain a mixed material. The process of step S107 that is performed is an example of a first determination process for determining whether or not the fluidity of the mixed material obtained in the first stirring process satisfies a determined condition.

Then, the process of step S106 performed after the second time is an example of the second stirring process of adding and mixing the solidifying material and water to the mixed material when the fluidity does not satisfy the conditions. The process of step S107 performed thereafter is an example of a second determination process for determining whether or not the fluidity of the mixed material obtained by adding and mixing the solidifying material and water in the second mixing process satisfies the conditions. .
Since the process of step S106 performed from the second time onwards is the second stirring process, the ratio of the water and the solidifying material contained in the mixed material at the end is equal to the ratio of the water and the solidifying material contained in the mixed material at the start and is repeated until the fluidity of the mixed material satisfies the condition in the second determination step.

That is, the method for producing solidified soil according to the embodiment described above can be conceptualized as follows.
A step of preparing a soil material with a known water content;
a first mixing step of adding at least a solidification material to the soil material and mixing with a batch-type stirrer to obtain a mixed material;
a first determination step of determining whether or not the fluidity of the mixed material obtained in the first mixing step satisfies a predetermined condition;
a second mixing step of adding and mixing a solidifying material and water to the mixed material when the fluidity does not satisfy the conditions;
a second determination step of determining whether or not the fluidity of the mixed material obtained by adding and mixing the solidifying material and the water in the second mixing step satisfies the condition;
A step of obtaining solidified soil by curing the mixed material satisfying the conditions in the first determination step or the second determination step;
has
In the second mixing step, the ratio of water to the solidifying material contained in the mixed material at the end is the same as the ratio of water to the solidifying material contained in the mixed material at the start, and the second determination A method for producing solidified soil, wherein the step is repeated until the fluidity of the mixed material satisfies the conditions.

In addition, as described above, the yield of the mixed material mixed in the stirrer may be used in the first determination step or the second determination step.
That is, the method for producing solidified soil according to the embodiment described above can be conceptualized as follows.
A method for producing solidified soil, wherein a yield of the mixed material mixed in the stirrer is used in the first determination step or the second determination step.

Also, as described above, in the first determination step or the second determination step, the results of at least one or more of the mixed material vane shear test, needle penetration test, and cone penetration test may be used.
That is, the method for producing solidified soil according to the embodiment described above can be conceptualized as follows.
In the first determination step or the second determination step, results of at least one or more of a vane shear test, a needle penetration test, and a cone penetration test of the mixed material are used. Soil manufacturing method.

<Modification>
The above is the description of the embodiment, but the content of this embodiment can be modified as follows. Also, the following modifications may be combined.

<Modification 1>
In the above-described embodiment, the manufacturer of the solidified soil satisfies the target value of the indoor blending strength and also satisfies the fluidity conditions. Having determined the weight ratio, the determined water/solidifying material weight ratio and water/soil particle weight ratio may be used to produce the required amount of solidified soil on site. The manufacturer of the solidified soil performs, for example, the steps from step S101 to step S104 of the steps from step S101 to step S107 described above as a laboratory test, and uses the numerical values determined in this laboratory test to perform on-site , a test for determining the water/soil particle weight ratio (hereinafter referred to as a field test), and production of the required amount of solidified soil may be performed.

In the case of on-site production, at least water among the amount of water and solidifying material to be added determined by the above-described laboratory test and field test should be added in multiple batches. For example, during the first stirring, the amount of solidifying material equivalent to the total amount of solidifying material in the laboratory test and the amount equivalent to less than half (half) the total amount of water determined in the laboratory test and field test of water may be added, and the remainder of the water may be added during the second agitation.

FIG. 5 is a diagram showing a method for producing solidified soil on site.
Step S201 shown in FIG. 5 is the process (laboratory test) from steps S101 to S104 in FIG. As a result of this laboratory test, the manufacturer of solidified soil determines the water/solidifying material weight ratio that satisfies the standard for unconfined compressive strength in all water/soil particle weight ratio ranges. . Then, after the laboratory test, the manufacturer determines the water content ratio of the soil material based on the above-mentioned "within the determined range", and adjusts the water content ratio of the raw material soil so that it becomes the determined water content ratio. When the water content ratio of the raw material soil is different from the determined water content ratio, the manufacturer either dries the raw material soil or adds water to the raw material soil. Accordingly, the manufacturer prepares a soil material with a known water content (step S202).

Next, the manufacturer acquires one batch of soil material from the soil material prepared in step S202 (step S203), and adds a solidifying agent (or a solidifying agent and water) to the acquired soil material. , with a batch-type stirrer installed on site (step S204). This addition is carried out so that the water/solidifying material weight ratio after addition and stirring becomes the water/solidifying material weight ratio determined in the laboratory test in step S201. This step S204 is the same step as step S106 shown in FIG. Thereby, a mixed material having a predetermined ratio of water and solidification material is produced. In step S204, the manufacturer may add only the solidifying material, or may add the solidifying material and water.

Here, the "mixed material" is a soil material to which at least a solidification material has been added, and is a material during stirring and mixing with a stirrer or the like, or immediately after stirring and mixing. Therefore, the mixed material is solidified soil that has not yet been completely solidified. The mixed material is cured for a predetermined period of time to solidify and become solidified soil.

The manufacturer of the solidified soil takes out the mixed material produced in step S204 from the agitator installed on site and determines whether or not its fluidity satisfies the conditions (step S205). For determination of this fluidity, the yield of the mixed material when taken out from the stirrer may be used, the shear strength of the solidified soil obtained by curing the taken out mixed material, or its shear strength A correlated (convertible) index may be used. This step S205 is the same step as step S107 shown in FIG.

When determining that the fluidity of the mixed material does not satisfy the conditions (step S205; NO), the manufacturer repeats steps S203 and S204. That is, the addition/stirring process in step S204 is such that the ratio of the water and the solidifying material contained in the mixed material at the end (after addition/stirring) is the same as the water contained in the mixed material at the start (before addition) and the solidification. The process is repeated until the fluidity of the mixed material satisfies the conditions. Needless to say, the above-mentioned step S204 can be repeated only before the added solidifying material begins to solidify.

On the other hand, if it is determined that the fluidity of the mixed material satisfies the conditions (step S205; YES), the manufacturer ends the field test and obtains one batch of soil material from the soil materials newly prepared in step S202. (step S206), and put into the stirrer described above.

The soil material acquired in step S206 is acquired from the same soil material prepared in step S202. Therefore, even considering the difference in acquisition timing, the soil material acquired in step S206 has the same moisture content as the soil material acquired in step S203 within a predetermined range (for example, ±3%). . The soil material acquired in step S206 is hereinafter referred to as a second soil material. Therefore, step S206 is an example of "a step of preparing a predetermined amount of a second soil material having a water content within a predetermined range and equal to the soil material used in the field test".

The manufacturer specifies the total amount of solidifying material and water that satisfy the target value of the indoor blending strength in the above-mentioned laboratory test and the fluidity condition in the field test, and the amount equivalent to the total amount of the solidifying material A solidifying material and half (half) water of the amount corresponding to the total amount of water are added to the second soil material (step S207). In this step S207, the step of specifying the total amount of the solidifying material and the water is "total amount of the solidifying material added to the soil material and water is an example of the step of specifying the total amount of

Then, the manufacturer agitates and mixes the second soil material to which the solidification material and water have been added in step S207 with a stirrer (step S208). The processes of steps S207 and S208 are performed by adding a solidification material in an amount corresponding to the specified total amount of the solidification material to the second soil material, and adding an amount equivalent to less than half of the specified total amount of water to the second soil material. It is an example of "the first stirring step of adding water and stirring with a stirrer".

After stirring and mixing in the first stirring step for a predetermined time, the manufacturer adds in step S207 the amount corresponding to the total amount of water when the fluidity satisfies the conditions in the above-described laboratory test. The remaining water that has not been added is added (step S209).

Then, the manufacturer agitates and mixes the second soil material to which the remaining water has been added in step S209 with a stirrer (step S210). By adding the remaining water, the cumulative amount of the water added in step S207 and the water added in step S209 corresponds to the total amount of water when the fluidity condition is satisfied in the laboratory test. It becomes the amount to do. In other words, the processes of steps S209 and S210 are performed by adding the remaining water to the second soil material so that the cumulative amount of added water after the stirring in the first stirring process corresponds to the total amount of water. It is an example of the second stirring step of adding and stirring with a stirrer.

After stirring and mixing in the second stirring step for a predetermined time, the manufacturer takes out the mixed material contained in the stirrer, and the manufacturer makes sure that the total amount of the taken-out mixed material reaches a predetermined amount. It is determined whether or not (step S211).

If it is determined that the total amount of mixed material taken out does not reach the predetermined amount (step S211; NO), the manufacturer returns to the process of step S206 and continues manufacturing the insufficient mixed material. On the other hand, when determining that the total amount of the mixed material taken out has reached the predetermined amount (step S211; YES), the manufacturer ends the process.

Based on the "water/solidification material weight ratio" specified in the laboratory test and the "water/soil particle weight ratio" specified in the field test, for a predetermined amount of newly obtained second soil material also determines the total amount of water and solidifying material to be added.

From the results of experiments conducted by the present inventors, in the on-site manufacturing process, when at least water is added in multiple batches, the amount of solidified soil produced is greater than when water is added all at once. It is derived that the strength increases. Therefore, as described above, at least water is desirably added in a plurality of times, such as two times.

An experimental example according to Modification 1 will be described below. Table 5 is a table showing the physical properties of the raw material soil used for the solidified soil. In this example, the present inventor used Nagoya Port Marine Clay, which is dredged soil, as raw material soil. The raw material soil shown in Table 5 differs from the raw material soil shown in Table 1 in physical properties due to different lots.

The present inventor measured the water content ratio of the raw material soil, added different amounts of solidifying material and water to the raw material soil, stirred them, and cured them for a predetermined period to prepare a plurality of samples.

The present inventor measured the uniaxial compressive strength of each sample for a plurality of prepared samples, and determined the standard for the uniaxial compressive strength in all the ranges in which the water / soil particle weight ratio was determined. The water/solidification weight ratio was determined. Here, "1.2" was adopted as the water/solidifying material weight ratio.

The present inventor dried the measured raw material soil or added water to the raw material soil to prepare a soil material in which the water/soil particle weight ratio was adjusted to a predetermined initial value. Here, "65%" was adopted as the initial value of the water/soil particle weight ratio. This prepared soil material is the above-mentioned "soil material with a known water content".

The present inventor added a solidification material (or a solidification material and water) to the prepared soil material and stirred it with a batch-type stirrer. This addition was carried out so that the water/solidifying material weight ratio after the addition and stirring was the water/solidifying material weight ratio "1.2" determined as described above. In other words, the inventor believes that the ratio of water to the solidifying material contained in the mixed material at the end (water/solidifying material weight ratio) is the ratio of water to the solidifying material contained in the mixed material at the start. 1.2", water and solidifying material were added and mixed.

The inventors determined whether or not the fluidity of the solidified soil produced satisfies the conditions, and repeated addition and stirring of water and solidifying material until it was determined that the conditions were satisfied. As a result, the present inventor determined the composition of the solidified soil.

Table 6 is a table showing the mix of solidified soil determined by laboratory tests and field tests. In the field test, addition and stirring were performed so that the water/solidifying material weight ratio determined by the laboratory test was maintained at "1.2". ” became. The water/soil particle weight ratio when it was determined in the field test that the fluidity of the solidified soil satisfied the condition was "100%" as shown in Table 6.

Next, the present inventor carried out on-site production of solidified soil based on the results of laboratory tests and field tests. That is, the inventor obtains one batch of the second soil material, puts it in a stirrer, and obtains an amount of solidifying material corresponding to the total amount of the specified solidifying material (total amount of solidifying material) and a total amount of water A half amount of water (half amount of water) was added to the second soil material, and the second soil material after addition was mixed by stirring (first stirring step).

As shown in Table 6, the second soil material whose initial water content is adjusted to 65% finally becomes a mixed material with a water/soil particle weight ratio of 100% and solidified soil. The total amount of water used is 35% of the dry weight (weight of soil particles) of the second soil material.

As shown in Table 6, the final water/solidifying material weight ratio is 1.2. A total amount of timber is specified. As described above, the water/soil particle weight ratio of the solidified soil is 100%, so the weights of water and soil particles used in the solidified soil are the same. That is, the total amount of solidification material is determined so that 1.2 times the total amount is equal to the dry weight (weight of soil particles) of the second soil material. In other words, the total amount of solidifying material added is about 0.833 times the dry weight of the second soil material.

Therefore, the present inventor added about 0.833 times the dry weight of the second soil material as a solidification material equivalent to the total amount of the solidification material specified in the laboratory test and the field test, and the indoor 17.5% of the dry weight of the second soil material was added as half the amount of water corresponding to the total amount of water specified in the tests and field tests.

Next, the present inventor added the remaining water that has not been added out of the amount corresponding to the total amount of water specified in the laboratory test and the field test, and stirred the second soil material after addition with a stirrer. (second stirring step). The weight of the remaining water is half the amount corresponding to the total amount of water, and thus 17.5% of the dry weight of the second soil material.

Then, the inventor took out the mixed material contained in the stirrer, determined whether or not the total amount reached the predetermined amount, and repeated the above-described process until the total amount reached the predetermined amount. The sample number of the sample of the mixed material manufactured by this manufacturing method is set to "41."

For comparison, the inventor also prepared samples in which the amount and order of water and solidifying material to be added were changed.

That is, as Comparative Example 1, the present inventor added an amount of water corresponding to the total amount of water to the second soil material placed in a stirrer, and mixed by stirring the second soil material after addition. After that, the inventor added a solidifying material in an amount corresponding to the total amount of the solidifying material to the second soil material, and mixed the second soil material after addition by stirring. That is, in Comparative Example 1, the total amount of water and solidifying material to be added was specified in laboratory tests, and only water was first added and stirred and mixed, and then only the solidifying material was added and stirred and mixed. be. The sample number of the mixed material sample produced by the method shown in Comparative Example 1 is "42".

In addition, as Comparative Example 2, the present inventor added a solidifying material in an amount corresponding to the total amount of the solidifying material to the second soil material placed in the agitator, and stirred the second soil material after addition to mix. did. After that, the inventor added an amount of water corresponding to the total amount of water to the second soil material, and mixed the second soil material by stirring. That is, in Comparative Example 2, the total amount of water and solidifying agent to be added was specified in laboratory tests, and only the solidifying agent was first added and stirred and mixed, and then only water was added and stirred and mixed. be. The sample number of the mixed material sample produced by the method shown in Comparative Example 2 is "43".

The present inventors tested the sample number "41" according to Modification Example 1, the sample number "42" according to Comparative Example 1, and the sample number "43" according to Comparative Example 2. Tests to evaluate the properties and strength were conducted respectively.

The present inventor used a needle penetration test in which a round bar with a diameter of 11.3 mm was penetrated into a specimen at a speed of 2 mm per minute as a test for evaluating fluidity. This needle penetration test is a needle penetration test according to JIS A1147:2007, and was performed on the sample immediately after it was taken out from the stirrer.

FIG. 6 is a diagram showing the needle penetration test results of the mixed material in Modification 1. As shown in FIG. The horizontal axis of FIG. 6 indicates needle penetration amount [mm], and the vertical axis indicates needle penetration resistance [kN/m ² ]. The dashed line shown in FIG. 6 is a line indicating that the needle penetration amount is 5 mm. m ² ]. As shown in FIG. 6, it was found that the 5 mm penetration resistance [kN/m ² ] of sample numbers 41 and 43 was smaller than that of sample number 42.

That is, it was found that sample numbers 41 and 43 had increased fluidity more than sample number 42. This means that if the total amount of water is first added and mixed, and then the total amount of the solidifying agent is added and mixed, the total amount of the solidifying agent is added and mixed, and then at least half of the water is added and mixed. This means that the liquidity is lower than in the case of

That is, to the second soil material, first, the solidification material is added in an amount corresponding to the total amount of the solidification material, and water is added in an amount corresponding to half or less of the total amount of water (half or zero). It has been found that adding the remainder of the water (either half or all) to the second soil material and stirring after stirring with a large amount increases the fluidity of the mixed material produced.

In addition, the inventor measured the air content of the mixed materials indicated by sample numbers 41 to 43 immediately after they were removed from the stirrer. Then, the inventor conducted a uniaxial compressive strength measurement test according to JIS A1108:2006 "Concrete Compressive Strength Test" as a test for evaluating strength. This uniaxial compressive strength measurement test was performed on samples obtained by curing the mixed materials shown by sample numbers 41 to 43 for 28 days.

FIG. 7 is a diagram showing the air content and uniaxial compressive strength of the mixed material in Modification 1. As shown in FIG. As shown in FIG. 7( a ), the sample of sample number 42 has a larger amount of air than the samples of sample numbers 41 and 43 . Generally, the greater the needle penetration resistance, the greater the air volume tends to be. Therefore, this experimental result, together with the needle penetration test result shown in FIG. 6 described above, agrees with this trend.

Moreover, as shown in FIG. 7(b), the unconfined compressive strength of these samples on the 28th day of material age was approximately 18 [MN/m ² ] or more and 23 [MN/m ² ] or less. The unconfined compressive strengths of the samples of Sample No. 41 and Sample No. 42 were comparable, and the unconfined compressive strength of the sample of Sample No. 43 was somewhat higher. From this result, first, to the second soil material, an amount of solidification material equivalent to the total amount of solidification material is added, and an amount of water equivalent to less than half of the total amount of water (half amount or zero) is added. After adding and stirring, it has been found that adding the remaining water (either half or all) to the second soil material and stirring increases the uniaxial compressive strength of the produced mixed material.

<Modification 2>
In the above-described modification 1, the manufacturing process at the site includes adding a solidification material in an amount equivalent to the total amount of the specified solidification material to the second soil material, and less than half of the specified total amount of water After the first stirring step of adding an amount of water corresponding to and stirring with a stirrer and stirring by the first stirring step, so that the cumulative amount of water added is an amount equivalent to the total amount of water, and a second stirring step of adding the remaining water to the second soil material and stirring with a stirrer. That is, in Modification 1, at least water was added in multiple portions in the manufacturing process on site after the field test, but water was added in multiple portions even in the field test. good too.

For example, in step S106 shown in FIG. 1, which is performed after the second time, the manufacturer first adds the total amount of the solidifying material and half of the water among the solidifying material and water to be added to the mixed material. Mix, then the remaining water may be added and mixed. In this case, in step S106 performed for the second and subsequent times, the solidifying material is added at once, but water is added in two steps. In other words, in step S106 performed for the second and subsequent times, at least water may be added and mixed in a plurality of times. In this case too, experiments have shown that the unconfined compressive strength of the mixed material obtained in laboratory tests is increased.
That is, the method for producing solidified soil according to the embodiment described above can be conceptualized as follows.
The method for producing solidified soil, wherein the second mixing step includes adding and mixing at least the water in a plurality of times.

Claims (3)

A step of preparing a soil material with a known water content;
a step of adding at least a solidification material to the soil material and stirring the mixture with a batch-type stirrer to produce solidified soil having a predetermined water-to-solidification ratio;
a step of determining whether or not the fluidity of the solidified soil satisfies a predetermined condition;
a step of adding a solidifying material and water to the solidified soil and stirring with the stirrer so that the ratio maintains the value until the fluidity is determined to satisfy the condition;
providing a predetermined amount of a second soil material having a water content equal to the soil material within a predetermined range;
a step of specifying the total amount of solidifying material added to the soil material and the total amount of water until it is determined that the fluidity satisfies the condition;
A solidifying material in an amount corresponding to the specified total amount of the solidifying material is added to the second soil material, and water is added in an amount corresponding to half or less of the specified total amount of water. A first stirring step of stirring with a stirrer;
After stirring in the first stirring step, the remaining water is added to the second soil material and stirred by the stirrer so that the cumulative amount of water added corresponds to the total amount of water. A second stirring step to
A method for producing solidified soil having 2. The production according to claim 1, wherein the yield of the solidified soil stirred by the stirrer is used in the step of determining whether the fluidity of the solidified soil satisfies the condition. Method. In the step of determining whether the fluidity of the solidified soil satisfies the conditions, the result of at least one of the vane shear test, needle penetration test, and cone penetration test of the solidified soil is used. 3. The manufacturing method according to claim 1 or 2, characterized in that:

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