JP7629347B2 - Method for estimating cement milk replacement rate and soil cement strength - Google Patents

Description

The present invention relates to a method for estimating the cement milk replacement rate and a method for estimating the strength of soil cement.

In underground structures constructed using soil cement, such as piles formed using the precast pile embedding method, a method is required to estimate the amount of cement in the soil cement and the proportion of cement milk in the soil cement for construction management and strength confirmation.

For example, the following Patent Document 1 describes a method of extracting an unconsolidated sample from the soil cement in the pile hole base protection section and estimating the amount of cement from the temperature change of this unconsolidated sample.

JP 2011-220092 A

In the method of estimating the amount of cement in the above-mentioned Patent Document 1, in order to create a graph showing the relationship between time and temperature, it is necessary to cure the unconsolidated sample for a certain period of time. As a result, it takes time to estimate the amount of cement. In addition, in order to accurately measure the temperature, it is necessary to cure the unconsolidated sample in an insulated container, which requires a lot of management work.

Taking the above facts into consideration, the present invention aims to estimate the proportion of cement milk in soil cement, i.e., the cement milk replacement rate, without ensuring a curing period.

The method for estimating the cement milk replacement rate of claim 1 includes the steps of drying an unconsolidated sample of soil cement formed by mixing cement milk and soil generated at a site, pulverizing the dried unconsolidated sample and measuring the content of a specific element in the unconsolidated sample using an X-ray fluorescence analyzer, calculating a mass ratio of soil to cement in the soil cement using the content of the specific element in the unconsolidated sample, the content of the specific element in the soil generated at the site, and the content of the specific element in the cement used in the cement milk, and calculating the volume fraction of the cement milk in the soil cement from the calculated mass ratio, the water content and density of the soil generated at the site, the density of the cement, and the mass ratio of water to cement in the cement milk.

Soil cement is made by mixing cement milk (a mixture of cement and water) with soil generated at the site, and it is difficult to grasp the mixture ratio of these two. For this reason, it is difficult to grasp the proportion of cement milk contained in soil cement.

Here, cement and on-site generated soil each contain various elements. If it is possible to focus on a specific element (a specified element, such as calcium) among these various elements and determine the content of the specified element in the soil cement and on-site generated soil, it is possible to calculate the percentage of cement milk contained in the soil cement.

Therefore, in the method for estimating the cement milk replacement rate of claim 1, the content of a specific element in an unconsolidated sample of soil cement is measured using an X-ray fluorescence analyzer. At this time, the unconsolidated sample is dried and pulverized, so that the cement components and the on-site generated soil components are mixed uniformly, and the content of the specific element can be measured with high accuracy.

Then, the mass ratio of soil to cement in the soil cement is calculated using the measured content of specific elements in the unconsolidated sample, the content of specific elements in the soil generated at the site, and the content of specific elements in the cement used in the cement milk.

Furthermore, the proportion of cement milk in the soil cement is calculated from the calculated mass ratio, the moisture content and density of the on-site soil, the density of the cement, and the mass ratio of water to cement in the cement milk.

In this way, the cement milk replacement rate estimation method of this embodiment makes it possible to estimate the proportion of cement milk in the soil cement, i.e., the cement milk replacement rate, without ensuring a curing period.
The method for estimating the cement milk replacement rate of claim 2 includes the steps of drying an unconsolidated sample of soil cement formed by mixing cement milk and soil generated at a site, crushing the dried unconsolidated sample and measuring the concentration of a predetermined element in the unconsolidated sample using a fluorescent X-ray analyzer, calculating a mass ratio of soil to cement in the soil cement using the concentration of the predetermined element in the unconsolidated sample, the concentration of the predetermined element in the soil generated at the site, and the concentration of the predetermined element in the cement used in the cement milk, and calculating the volume fraction of the cement milk in the soil cement from the calculated mass ratio, the water content and density of the soil generated at the site, the density of the cement, and the mass ratio of water to cement in the cement milk.
The cement milk replacement rate estimation method of claim 3 is the cement milk replacement rate estimation method of claim 2, in which the concentration of a specified element in the unconsolidated sample is Ca(sc), the concentration of the specified element in the on-site generated soil is Ca(s), the concentration of the specified element in the cement used in the cement milk is Ca(c), and the mass ratio is α, and the following equation (A) holds.
α=[Ca(c)-Ca(sc)]/[Ca(sc)-Ca(s)]...(A)
The method for estimating a cement milk replacement rate of claim 4 is the method for estimating a cement milk replacement rate of claim 2 or 3, wherein the water content of the on-site generated soil is ωs, the density of the on-site generated soil is ρs, the density of the cement is ρc, the mass ratio of water to cement in the cement milk is R, and the volume fraction of the cement milk in the soil cement is Vh, and the following equation (B) holds.
Vh=1/[1+α・{(1/ρs)+ωs}/{(1/ρc)+R}]...(B)
The method for estimating a cement milk replacement ratio according to claim 5 is the method for estimating a cement milk replacement ratio according to claim 2, further comprising the steps of: defining a concentration of a predetermined element in the unconsolidated sample as Ca(sc); defining a concentration of the predetermined element in the on-site generated soil as Ca(s); defining a concentration of the predetermined element in the cement used in the cement milk as Ca(c); defining the mass ratio as α; defining a water content of the on-site generated soil as ωs;
The density of the on-site soil is ρs, the density of the cement is ρc, the mass ratio of water to cement in the cement milk is R, and the volume fraction of the cement milk in the soil cement is Vh, the following equations (A) and (B) hold.
α=[Ca(c)-Ca(sc)]/[Ca(sc)-Ca(s)]...(A)
Vh=1/[1+α・{(1/ρs)+ωs}/{(1/ρc)+R}]...(B)

The method for estimating a cement-milk replacement rate of claim 6 is the method for estimating a cement-milk replacement rate of claim 1 , wherein the content of a predetermined element in the on-site generated soil is measured by crushing the dried on-site generated soil and using an X-ray fluorescence analyzer.

In the method for estimating the cement milk replacement rate of claim 6 , the content of a specific element in the on-site generated soil is dried and crushed, and measured using a fluorescent X-ray analyzer. This makes it possible to obtain a higher accuracy in the content of a specific element in the on-site generated soil than when the content of a specific element in the on-site generated soil based on previous data is used.

The method for estimating a cement-milk replacement rate of claim 7 is the method for estimating a cement-milk replacement rate of claim 1 , wherein the soil cement forms a foot protection portion of a pile hole.

In the method for estimating the cement milk replacement rate of the seventh aspect of the present invention , the cement milk replacement rate of the soil cement forming the base protection part of the pile hole can be estimated. This makes it possible to grasp the mixing condition of the cement milk and the soil in the base protection part and estimate the strength of the base protection part.

The soil cement strength estimation method of claim 8 estimates the compressive strength of soil cement using correlation data between the proportion of cement milk in soil cement and compressive strength, and the proportion of cement milk in soil cement calculated by the cement milk replacement rate estimation method of any one of claims 1 to 7 .

In the soil cement strength estimation method of claim 8 , the compressive strength of the soil cement is estimated from correlation data between the proportion of cement milk in the soil cement and the compressive strength. This makes it possible to estimate the strength of the soil cement without ensuring a curing period until the soil cement hardens.

According to the present invention, it is possible to estimate the cement milk replacement rate without ensuring a curing period.

(A) is an elevational cross-sectional view showing the state of forming a pile hole for burying a precast pile to which the cement milk replacement rate estimation method and soil cement strength estimation method of the present invention are applied, (B) is an elevational cross-sectional view showing the state of forming a foot protection portion in the pile hole, (C) is an elevational cross-sectional view showing the state of pulling up a drilling rod from the pile hole, and (D) is an elevational cross-sectional view showing the state of inserting a precast pile into the pile hole. FIG. 1 is a conceptual diagram showing the components of soil cement. 1 is a graph showing correlation data between the cement milk replacement rate of soil cement and compressive strength. FIG. 1 is a conceptual diagram showing the components of soil cement in a dry state.

The following describes a method for estimating the cement milk replacement rate and a method for estimating soil cement strength according to an embodiment of the present invention, with reference to the drawings. Components indicated with the same reference numerals in each drawing are the same components. However, unless otherwise specified in the specification, each component is not limited to one, and there may be multiple components.

In addition, explanations of configurations and symbols that are duplicated in each drawing may be omitted. Note that the present invention is not limited to the following embodiments, and may be implemented with appropriate modifications, such as omitting configurations or replacing them with different configurations, within the scope of the purpose of the present invention.

<Pile construction method>
The method for estimating the cement milk replacement rate and the method for estimating the strength of soil cement according to the embodiment of the present invention are used, for example, for the soil cement forming the base of a pile. Therefore, prior to the explanation of these methods, an outline of a construction method for a pile using the soil cement for which the cement milk replacement rate and strength are to be estimated will be given.

Figures 1 (A) to (D) show an example of a method for embedding a precast pile 10 in ground G using an embedding method. The precast pile 10 shown in Figure 1 (D) is a concrete pile that is precast in a factory or the like and then transported to the construction site.

To bury the precast pile 10 in the ground G, first, as shown in FIG. 1(A), the ground G is excavated using a drilling rod 20 while injecting drilling fluid to form a pile hole GH. In this embodiment, the tip of the pile hole GH is made to reach the supporting layer GA so that the precast pile 10 serves as a tip-support pile.

Next, as shown in FIG. 1(B), cement milk is injected from the drilling rod 20 into the tip (bottom) of the pile hole GH. This cement milk is stirred and mixed with the soil in the ground G to form the soil cement 12 that forms the foot protection section.

Cement milk is formed by mixing cement and water, or by mixing cement, water, and various additives. Soil cement is a mixture of cement milk and soil. In this specification, the mixture of minerals, organic matter, gas, liquid, and living organisms that form the "ground G" is referred to as "soil."

At the tip of the pile hole GH, it is preferable to form a root-stabilizing bulb 12A, which is a portion where the diameter of the pile hole GH is expanded and filled with soil cement 12. When forming the root-stabilizing bulb 12A, the drilling head of the drilling rod 20 has a known structure that allows it to be expanded. The drilling head is then expanded at a predetermined depth to form the root-stabilizing bulb 12A.

Next, as shown in FIG. 1(C), while the drilling rod 20 is being withdrawn, cement milk is injected and stirred above the soil cement 12. This forms soil cement 14 as a fixing liquid around the pile. The soil cement 14 may be formed using lean cement milk that has a smaller amount of cement per unit volume compared to the soil cement 12.

Next, as shown in FIG. 1(D), the prefabricated pile 10 is inserted into the pile hole GH. At this time, the tip of the prefabricated pile 10 is depressed into the root-hardening bulb 12A at the tip of the pile hole GH. This causes the prefabricated pile 10 to be buried in the ground G.

<Pile strength estimation method>
The soil cement strength estimation method according to the embodiment of the present invention is a method for estimating the strength of the soil cement 12, which is, for example, the base reinforcement portion of a precast pile 10, after hardening.

The reason for estimating the strength of the soil cement 12 after solidification is that the bearing capacity of the precast pile 10 is affected by the strength of the soil cement 12. Specifically, the soil cement 12 integrates the tip portion of the precast pile 10 with the supporting layer GA, and resists the pressing force acting on the precast pile 10. For this reason, when evaluating the bearing capacity of the precast pile 10, it is preferable to estimate the strength of the soil cement 12 in addition to the strength of the precast pile 10 itself.

In addition, "estimating" the strength of the soil cement 12 after it has solidified means evaluating the strength of the soil cement 12 before it has solidified. In this case, compared to when the strength of the soil cement 12 is "measured" after it has solidified, there is no need to ensure a curing period until the soil cement 12 has solidified. This makes it possible to shorten the construction period.

In this embodiment, the soil cement used to estimate the strength does not have to be the one used for permanent piles, but can be soil cement with approximately the same composition as that used for permanent piles.

In this case, a temporary pile hole is drilled on the same site as the precast pile 10 as the permanent pile, and cement milk is injected and stirred. This makes it possible to form soil cement with approximately the same composition as the soil cement 12 used for the permanent pile. "Approximately the same" means, for example, that the mixture ratio of cement and soil is approximately the same.

In addition, the soil cement for which strength is estimated in this embodiment does not necessarily have to be used in the base of the pile, but may be used in parts other than the base of the pile. Furthermore, the soil cement may be used in an earth retaining wall or a ground improvement body. In the following explanation, a method for estimating the strength of soil cement in general, including the soil cement 12 used in permanent piles, will be described.

(Outline of soil cement strength estimation method)
The strength of soil cement can be estimated from correlation data between the cement milk replacement rate Vh and compressive strength if the ratio of the volume of cement milk to a unit volume of soil cement, i.e., the cement milk replacement rate Vh, is known. The correlation data between the cement milk replacement rate Vh and compressive strength (uniaxial compressive strength qu [N/ ^mm2 ]) can be obtained as known information, for example, as shown in Figure 3. The example shown in Figure 3 shows a case where the water-cement ratio of cement milk is 60%.

In Figure 3, the measured values of the unconfined compressive strength are plotted for multiple samples with various cement milk replacement rates Vh. Figure 3 also shows an approximation line C1 that approximates these plotted points with a linear curve. The unconfined compressive strength corresponding to the cement milk replacement rate Vh of the sample is derived in a one-to-one correspondence from the approximation line C1.

(cement milk replacement rate)
As shown in Fig. 2, the cement milk that forms the soil cement is formed by kneading, for example, C [g] of cement and C × R [g] of water. R is the water-cement ratio (mass ratio) in the cement milk, and is a known value that can be set arbitrarily.

The on-site generated soil, which is the soil that is mixed with the cement milk, contains soil particles (in a dry state) of S [g] and water of S x ωs [g]. ωs is the water content (mass ratio) of the on-site generated soil, and is a value that can be measured by a preliminary survey, which will be described later.

If the density of cement is ρc [g/cm ³ ] and the density of soil particles is ρs [g/cm ³ ], then the volume of cement C [g] is (C/ρc) [cm ³ ], and the volume of soil particles S [g] is (S/ρs) [cm ³ ]. Furthermore, if the density of water is 1, then the volume of water in (C x R) [g] is (C x R) [cm ³ ], and the volume of water in (S x ωs) [g] is (S x ωs) [cm ³ ].

That is, the volume of cement milk Vcm [cm ³ ] is expressed by the following formula (1-1).

Vcm=C・[(1/ρc)+R]...(1-1)

The volume of the on-site generated soil Vsl [cm ³ ] is given by the following formula (1-2).

Vsl=S・[(1/ρs)+ωs]...(1-2)

Furthermore, the ratio of the volume of cement milk to a unit volume of soil cement, i.e., the "cement milk replacement rate" Vh, is given by the following formula (1-3).

Vh=Vcm/(Vcm+Vsl)...(1-3)

As mentioned above, the strength of soil cement can be estimated from the correlation data between the cement milk replacement rate Vh and compressive strength, if the cement milk replacement rate Vh is known. However, since it is difficult to determine the mixture ratio of cement milk and on-site generated soil in soil cement, it is difficult to determine the cement content C[g] in the soil cement. For this reason, it is also difficult to determine the cement milk replacement rate.

Here, both the cement and the on-site generated soil contain calcium. If the calcium content of the soil cement and the on-site generated soil can be determined, the cement milk replacement rate Vh of the soil cement can be calculated using the method described below. Note that calcium is an example of a specified element in the present invention. The "specified element" used in the present invention may be any element that is contained in cement, such as calcium.

(Calcium concentration of cement, density and water-cement ratio of cement milk)
The calcium concentration Ca(c) [ppm] of the cement used in soil cement is known information. For example, as shown in Figure 4, the calcium content Cca in cement C[g] is expressed by the following formula (2). The calcium concentration of cement may be measured using an X-ray fluorescence analyzer.

Cca=C・Ca(c)...(2)

The cement density ρc [g/cm ³ ] is also known information. Furthermore, the water-cement ratio R in the cement milk is a known value that can be set arbitrarily as described above. Cement and water are mixed to obtain a predetermined water-cement ratio, but it is preferable to check the water-cement ratio R of the cement milk to be injected into the pile hole GH shown in Figure 1 when the cement milk is produced at the plant.

(Preliminary survey - sample collection)
In order to estimate the strength of soil cement, a preliminary investigation is carried out. As an example of the preliminary investigation, first, a sample of on-site generated soil is collected from the ground (for example, ground G shown in FIG. 1). It is preferable to collect the sample in conjunction with a boring test for a ground investigation. The sample is, for example, the on-site generated soil (hereinafter, sometimes referred to as a "soil sample") that forms the bearing layer GA shown in FIG. 1.

(Preliminary survey - measurement of soil generated at the site)
Next, the mass of the collected soil sample is measured, then it is dried and pulverized. Any equipment such as a heat-drying moisture meter or a microwave oven can be used to dry the soil sample. A mill or the like can be used to pulverize the soil sample. The mass and volume of the dried soil sample are then measured.

This makes it possible to determine the density of the soil particles (in a dry state), ρs [ ^cm3 ], and the water content ωs of the soil sample before drying. As shown in Figure 2, the soil sample contains soil particles (in a dry state), S [g], and water, S·ωs [g].

(Preliminary survey - measurement of calcium content in on-site soil)
Next, the calcium concentration in the dried and crushed soil sample (soil particles) is measured using an X-ray fluorescence analyzer. As shown in Figure 4, when the calcium concentration in the soil particles (in a dry state) is measured as Ca(s) [ppm], the calcium content Sca in the soil particles (in a dry state) of S [g] is expressed by the following formula (3).

Sca=S・Ca(s)...(3)

(Measurement of calcium content in soil cement)
Next, for example, the cement milk and the on-site generated soil are mixed inside the pile hole GH shown in Figure 1 to form soil cement. Then, the unconsolidated soil cement is collected as an unconsolidated sample.

Next, the collected unconsolidated samples are dried and pulverized. As with soil samples, any equipment can be used to dry unconsolidated samples, such as a heat-drying moisture meter or a microwave oven. Unconsolidated samples can be pulverized using a mill or similar device. The time required for drying using a microwave oven or similar device, pulverization, and calcium measurement is approximately 1 hour (of which drying using a heat-drying moisture meter takes approximately 30 minutes and drying using a microwave oven takes approximately 15 minutes), which is sufficiently short compared to the time required for testing and curing the specimens for uniaxial compression tests (approximately 3 to 7 days).

Next, an X-ray fluorescence analyzer is used to measure the calcium concentration in the dried and crushed unconsolidated sample (i.e., dry soil cement). At this time, since the unconsolidated sample is dried and crushed, the cement components and the on-site generated soil components are mixed uniformly, and the calcium content can be measured with high accuracy.

As shown in Figure 4, when the calcium concentration of soil cement (dry state) is measured as Ca(sc) [ppm], the calcium content Cca + Sca in this soil cement (dry state) is expressed by the following formula (4).

Cca+Sca=(C+S)・Ca(sc)...(4)

(Mass ratio of cement to soil particles (dry state) in soil cement)
As shown in FIG. 4, if the mass ratio C:S of cement to soil particles (in a dry state) in soil cement is 1:α, then this coefficient α (hereinafter referred to as the mass ratio α) is expressed by the following equation (5-1).

α=S/C...(5-1)

The calcium concentration Ca(sc) in soil cement is expressed by the following formula (5-2) from formulas (2), (3), and (4).

Ca(sc)=[C・Ca(c)+S・Ca(s)]/(C+S)...(5-2)

Using Ca(c), Ca(s), and Ca(sc), the mass ratio α is calculated as follows (5).

α=[Ca(c)-Ca(sc)]/[Ca(sc)-Ca(s)]...(5)

(Cement milk replacement rate in soil cement)
The ratio between the volume of cement milk in soil cement, Vcm [cm ³ ], and the volume of the on-site generated soil, Vsl [cm ³ ], is given by the following equation (1-4), based on the above equations (1-1) and (1-2).

Vcm: Vsl=1: (S/C)・[(1/ρs)+ωs]/[(1/ρc)+R]
... (1-4)

Using equation (5-1), equation (1-4) can be expressed as the following equation (1-5).

Vcm:Vsl=1:α・[(1/ρs)+ωs]/[(1/ρc)+R]
... (1-5)

If we set the coefficient X = α · [(1/ρs) + ωs] / [(1/ρc) + R], then equation (1-5) can be expressed as the following equation (1-6).

Vcm:Vsl=1:X...(1-6)

From equations (1-3) and (1-6), the cement milk replacement ratio Vh is given by the following equation (1): That is, the cement milk replacement ratio Vh is given by the coefficient X derived from the mass ratio α of cement to soil particles (in a dry state) in the soil cement, the density ρs [cm ³ ] of the soil particles (in a dry state), the water content ωs of the soil sample before drying, the density ρc [g/cm ³ ] of the cement, and the water-cement ratio R of the cement milk, all of which are calculated or measured in the above steps.

Vh=1/(1+X)...(1)

(Estimation of soil cement strength)
Next, the strength of the soil cement (unconfined compressive strength) is estimated from the correlation data between the cement milk replacement rate Vh and compressive strength shown in Figure 3. Specifically, the value of the unconfined compressive strength corresponding to the calculated cement milk replacement rate Vh on the approximation line C1 is estimated as the strength of the soil cement. This allows the unconfined compressive strength of the unconsolidated soil cement sample to be estimated when it is solidified.

(Action and Effects)
In this way, according to the soil cement strength estimation method and cement milk replacement rate estimation method of this embodiment, it is possible to estimate the strength without ensuring the curing period until the soil cement hardens.

If the estimated strength is less than the design strength, the strength of the soil cement can be increased to the design strength by injecting additional cement milk before the soil cement in the pile hole GH hardens.

In addition, if the soil cement whose strength has been estimated is the soil cement used to form temporary piles, the strength of the soil cement in the permanent piles can be increased to the design strength by using a rich blend of cement milk to be injected into the permanent piles.

In addition, by making the injection rate of cement milk (amount of cement milk injected / e.g. amount of excavation in the base protection section) sufficiently large, the amount of cement milk injected in the base protection section can be reduced compared to the case where compressive strength testing is omitted while ensuring the strength of the base protection section. This reduces material costs.

In the above embodiment, the cement milk replacement rate is estimated, and then the soil cement strength is estimated using the estimated value, but the embodiment of the present invention is not limited to this. For example, after estimating the cement milk replacement rate, it is not necessary to estimate the soil cement strength.

For example, the soil cement 12 forming the root protection section shown in Figure 1 is applied by injecting cement milk at a predetermined volume ratio relative to the volume of the root protection section. Then, unconsolidated soil cement is collected as an unconsolidated sample, and the cement milk replacement rate is estimated according to the above process. This makes it possible to confirm whether the cement milk has been injected at the predetermined volume ratio into the root protection section.

Furthermore, the above method allows the cement milk replacement rate to be estimated on-site, in a short time, and in a simple manner with high accuracy.

In contrast, a conventional method for estimating concrete mix proportions involves heating the concrete to temperatures such as 110°C, 600°C, and 1000°C to determine the various moisture contents. This type of drying takes time and requires large-scale equipment. In addition, it is not easy to transport the equipment to the site.

Another example of a conventional method for estimating the mix proportions of concrete is to analyze the calcium oxide in the solution obtained by dissolving concrete in acid and filtering it to determine the amount of cement, and then use the residue to determine the amount of aggregate. This type of chemical analysis requires specialized knowledge, so there are limited personnel who can carry out the work. In addition, the acid can dissolve calcium components in shells and other materials, which can lead to an overestimation of the amount of cement, making it difficult to use this method on sea sand, etc.

12 Soil cement

Claims (8)

Drying an unconsolidated sample of soil cement formed by mixing the cement milk with the on-site generated soil;
A step of crushing the dried unconsolidated sample and measuring the content of a predetermined element in the unconsolidated sample using an X-ray fluorescence analyzer;
Calculating the mass ratio of soil to cement in the soil cement using the content of a predetermined element in the unconsolidated sample, the content of the predetermined element in the on-site generated soil, and the content of the predetermined element in the cement used in the cement milk;
A step of calculating the volume ratio of the cement milk in the soil cement from the calculated mass ratio, the water content and density of the site generated soil, the density of the cement, and the mass ratio of water to cement in the cement milk;
A method for estimating cement milk replacement rate comprising: Drying an unconsolidated sample of soil cement formed by mixing the cement milk with the on-site generated soil;
pulverizing the dried unconsolidated sample and measuring the concentration of a predetermined element in the unconsolidated sample using an X-ray fluorescence analyzer;
Calculating the mass ratio of soil to cement in the soil cement using the concentration of a predetermined element in the unconsolidated sample, the concentration of the predetermined element in the on-site generated soil, and the concentration of the predetermined element in the cement used in the cement milk;
A step of calculating the volume ratio of the cement milk in the soil cement from the calculated mass ratio, the water content and density of the site generated soil, the density of the cement, and the mass ratio of water to cement in the cement milk;
A method for estimating cement milk replacement rate comprising: The concentration of a given element in the unconsolidated sample is Ca(sc),
The concentration of the specified element in the on-site generated soil is Ca(s),
The concentration of the predetermined element in the cement used in the cement milk is Ca(c),
The mass ratio is α,
The following formula (A) holds:
The method for estimating cement milk replacement rate according to claim 2.
α=[Ca(c)-Ca(sc)]/[Ca(sc)-Ca(s)]...(A) The water content of the on-site generated soil is ωs,
The density of the site generated soil is ρs,
The density of the cement is ρc,
The mass ratio of water to cement in the cement milk is R;
The volume ratio of the cement milk in the soil cement is Vh,
The following formula (B) holds true:
The method for estimating cement milk replacement rate according to claim 2 or 3.
Vh=1/[1+α・{(1/ρs)+ωs}/{(1/ρc)+R}]...(B) The concentration of a given element in the unconsolidated sample is Ca(sc),
The concentration of the specified element in the on-site generated soil is Ca(s),
The concentration of the predetermined element in the cement used in the cement milk is Ca(c),
The mass ratio is α,
The water content of the on-site generated soil is ωs,
The density of the site generated soil is ρs,
The density of the cement is ρc,
The mass ratio of water to cement in the cement milk is R;
The volume ratio of the cement milk in the soil cement is Vh,
The following formulas (A) and (B) hold:
The method for estimating cement milk replacement rate according to claim 2.
α=[Ca(c)-Ca(sc)]/[Ca(sc)-Ca(s)]...(A)
Vh=1/[1+α・{(1/ρs)+ωs}/{(1/ρc)+R}]...(B) The method for estimating a cement milk replacement rate according to any one of claims 1 to 5 , wherein the content of the predetermined element in the on-site generated soil is measured by crushing the dried on-site generated soil and using a fluorescent X-ray analyzer. The method for estimating a cement milk replacement rate according to any one of claims 1 to 6 , wherein the soil cement forms a base protection portion of a pile hole. A method for estimating soil cement strength, comprising: estimating the compressive strength of soil cement using correlation data between the proportion of cement milk in soil cement and compressive strength; and the proportion of cement milk in soil cement calculated by the method for estimating cement milk replacement rate according to any one of claims 1 to 7.