Soil cement unit volume mass estimation method and soil cement strength estimation method

Abstract

To accurately estimate a unit volume mass of soil cement.SOLUTION: A soil cement unit volume mass estimation method includes the steps of: drying an unconsolidated sample of soil cement formed by mixing cement milk and on-site excessive soil; crushing the dried unconsolidated sample, and measuring a predetermined element content of the unconsolidated sample, using a fluorescent X-ray analyzer; calculating a mass ratio of soil and cement in the soil cement, using the predetermined element content of the unconsolidated sample, a predetermined element content of the on-site excessive soil and a predetermined element content of cement used in the cement milk; and calculating the unit volume mass of the soil cement, from the calculated mass ratio, soil particle density of the on-site excessive soil, density of the cement and a moisture content of the soil cement.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for estimating unit volume mass of soil cement and a method for estimating strength of soil cement. [Background technology]

[0002] In underground structures constructed using soil cement, such as piles formed using the precast pile embedding method, it is necessary to understand the strength (solidification strength) of the soil cement in order to confirm its strength and manage its construction.

[0003] For example, Patent Document 1 listed below describes a method for estimating the strength of soil cement by extracting an unconsolidated sample from the soil cement in a pile hole base protection section and estimating the amount of cement from the temperature change of this unconsolidated sample. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-220092 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the method for 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. Therefore, 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 is time-consuming to manage.

[0006] Therefore, it is possible to determine the "mass" per unit volume of soil cement without setting such a curing period. If the mass can be determined, the ratio of cement milk in the soil cement can be determined, and the strength of the soil cement can be derived.

[0007] In order to determine the mass of soil cement without a curing period, there are several methods, such as using a mud balance to measure the mass of an unconsolidated sample, or using a scale to measure the mass of an unconsolidated sample filled into a container.

[0008] However, in the method using a mud balance, soil particles can get caught in the lid of the cup in which the sample is filled, making it difficult to close the lid, or the hole in the lid can get clogged, making it difficult to measure the mass accurately.In addition, measurements are made by workers visually or manually, which is prone to errors.

[0009] On the other hand, when using a container and a scale, it is difficult to grasp the position of the liquid surface of the soil cement poured into the container, and it is difficult to measure the volume. Therefore, when converting to mass per unit volume, errors are likely to occur.

[0010] Taking into consideration the above facts, the present invention aims to accurately estimate the unit volume mass of soil cement. [Means for solving the problem]

[0011] The method for estimating unit volume mass of soil cement of claim 1 comprises 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 content of a predetermined 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 predetermined element content of the unconsolidated sample, the predetermined element content of the soil generated at the site and the predetermined element content of the cement used in the cement milk, and calculating the unit volume mass of the soil cement from the calculated mass ratio, the soil particle density of the soil generated at the site, the density of the cement and the water content of the soil cement.

[0012] In the method for estimating the unit mass of soil cement as claimed in 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 component and the on-site generated soil component are mixed uniformly, and the content of the specific element can be measured with high accuracy.

[0013] 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.

[0014] Furthermore, the unit volume mass of the soil cement is calculated from the calculated mass ratio, the soil particle density of the on-site generated soil, the cement density, and the water content of the soil cement.

[0015] In this way, the method for estimating the unit mass of soil cement according to the present embodiment can estimate the unit mass of soil cement by calculation, which reduces the variation caused by manual measurement.

[0016] The method for estimating the unit volume mass of soil cement of claim 2 is the method for estimating the unit volume mass of soil cement of claim 1, in which the content of specified elements in the on-site generated soil is measured by pulverizing the dried on-site generated soil and using an X-ray fluorescence analyzer.

[0017] In the method for estimating the unit volume mass of soil cement of claim 2, the content of a specific element in the on-site generated soil is dried and crushed, and measured using an X-ray fluorescence analyzer. This provides a higher accuracy in estimating the content of a specific element in the on-site generated soil compared to using the content of a specific element in the on-site generated soil based on previous data.

[0018] A method for estimating a unit volume mass of soil cement according to claim 3 is the method for estimating a unit volume mass of soil cement according to claim 1, wherein the soil cement forms a foot protection portion of a pile hole.

[0019] The method for estimating the unit mass of soil cement of claim 3 can estimate the unit mass of the soil cement forming the base protection part of the pile hole. 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.

[0020] In addition, a method for estimating a unit volume mass of soil cement according to claim 3 may be the method for estimating a unit volume mass of soil cement according to claim 1 or 2, in which the soil cement forms a foot protection portion of a pile hole.

[0021] The soil cement strength estimating method of claim 4 calculates the proportion of cement milk in the soil cement from the unit volume mass of the soil cement calculated by the soil cement unit volume mass estimating method of any one of claims 1 to 3, and estimates the compressive strength of the soil cement using correlation data between the proportion of cement milk in the soil cement and the compressive strength.

[0022] In the soil cement strength estimation method of claim 4, 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. Effect of the Invention

[0023] According to the present invention, the unit volume mass of soil cement can be estimated with high accuracy. [Brief description of the drawings]

[0024] [Figure 1] 1A is an elevational sectional view showing the state of forming a pile hole for burying a precast pile to which the soil cement unit volume mass estimation method and soil cement strength estimation method of the present invention are applied, (B) is an elevational sectional view showing the state of forming a foot protection portion in the pile hole, (C) is an elevational sectional view showing the state of pulling up a drilling rod from the pile hole, and (D) is an elevational sectional view showing the state of inserting a precast pile into the pile hole. [Diagram 2] 1 is a graph showing correlation data between the cement milk replacement rate of soil cement and compressive strength. [Diagram 3] FIG. 1 is a conceptual diagram showing the components of soil cement in a dry state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, a method for estimating the unit mass of soil cement and a method for estimating the strength of soil cement according to an embodiment of the present invention will be described with reference to the drawings. Components indicated by 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 may be present in multiple numbers.

[0026] In addition, the description of the same configuration and reference numerals in each drawing may be omitted. Note that the present invention is not limited to the following embodiment, and may be modified as appropriate within the scope of the object of the present invention, such as omitting configurations or replacing them with different configurations.

[0027] <Pile construction method> The method for estimating the unit volume mass of soil cement 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 that forms 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 that is the subject of the estimation of the unit volume mass and strength will be given.

[0028] 1(A) to 1(D) show an example of a method for embedding a precast pile 10 in ground G by an embedding method. The precast pile 10 shown in Fig. 1(D) is a concrete pile or a steel pipe pile, and is manufactured in a factory or the like and then transported to a construction site.

[0029] In order to bury the precast pile 10 in the ground G, first, as shown in Fig. 1(A), the ground G is excavated while injecting drilling fluid using a drilling rod 20 to form a pile hole 30. In this embodiment, a case will be described in which the tip of the pile hole 30 is made to reach the bearing layer GA in order to make the precast pile 10 a tip-support pile.

[0030] At this time, it is preferable to form a root-fixing bulb 32, which is a portion where the diameter of the pile hole 30 is enlarged, at the tip of the pile hole 30. When forming the root-fixing bulb 32, the drilling head of the drilling rod 20 is structured so as to be enlarged in diameter, as shown in Fig. 1(A). Then, the drilling head is enlarged at a predetermined depth, whereby the root-fixing bulb 32 is formed.

[0031] In the present invention, it is not always necessary to form the root-hardening bulb 32. Regardless of whether the root-hardening bulb 32 is formed or not, when excavating the tip portion of the pile hole 30, cement milk is injected from the drilling rod 20 to the tip (bottom) of the pile hole 30. By stirring this cement milk, the cement milk is mixed with the soil in the ground G, and the soil cement 12, which is a root-hardening liquid that forms the root-hardening portion, is formed.

[0032] The cement milk may be injected while excavating the tip of the pile hole 30, or may be injected while pulling up the drilling rod 20 after excavating the tip of the pile hole 30. As will be described in detail later, the present invention relates to a method of injecting cement milk for forming the soil cement 12 of the foot protection portion.

[0033] 1(B) and (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.

[0034] Next, as shown in FIG. 1(D), the precast pile 10 is inserted into the pile hole 30. At this time, the tip of the precast pile 10 is depressed into the root-stabilizing bulb 32 at the tip of the pile hole 30. As a result, the precast pile 10 is buried in the ground G. Note that the ratio between the hole diameter of the pile hole 30 and the pile diameter of the precast pile 10 shown in each figure is only schematic. In reality, as an example, the hole diameter of the pile hole 30 can be made approximately 30 mm larger than the pile diameter of the precast pile 10.

[0035] <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 soil cement 12, which is the base protection portion of a precast pile 10, for example, after hardening.

[0036] 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 bearing 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.

[0037] Furthermore, "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 "measuring" the strength of the soil cement 12 after it has solidified, there is no need to secure a curing period until the soil cement 12 has solidified. This makes it possible to shorten the construction period.

[0038] In this embodiment, the soil cement for estimating the strength does not have to be that used for permanent piles, and may be soil cement with approximately the same composition as that used for permanent piles.

[0039] In this case, a temporary pile hole is drilled on the same site as the site where the precast pile 10 as the permanent pile will be installed, 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.

[0040] 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, and may be used in parts other than the base of the pile. Furthermore, the soil cement may be used in an earth retaining wall (soil cement wall) or a ground improvement body (formed by mechanical mixing or high-pressure injection mixing of soil cement). 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.

[0041] (Outline of soil-cement strength estimation method) The strength of soil cement can be estimated from the correlation data between the cement milk replacement rate Vh and compressive strength if the ratio of the volume of cement milk to the unit volume of soil cement, i.e., the cement milk replacement rate Vh, is known. 2 ]) can be obtained as known information, for example, as shown in Fig. 2. The example shown in Fig. 2 shows a case where the water-cement ratio of the cement milk is 60%.

[0042] In Fig. 2, the measured values ​​of the unconfined compressive strength of a number of samples having various cement milk replacement rates Vh are plotted. In addition, Fig. 2 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 one-to-one correspondence from the approximation line C1.

[0043] (Calcium concentration and density of cement) The calcium concentration Ca(c) [ppm] and density ρc [g / cm 3] is known information. Of these, the calcium content Cca in the cement of C[g] is calculated by the following formula (1), as shown in Figure 3. The calcium concentration in the cement may be measured using an X-ray fluorescence analyzer.

[0044] Cca = C × Ca(c) (1)

[0045] (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. This sample is, for example, the on-site generated soil (hereinafter sometimes referred to as the "soil sample") that forms the bearing layer GA shown in FIG. 1.

[0046] (Preliminary survey - measurement of soil generated on 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.

[0047] This gives the density of the soil particles (dry state), ρs [g / cm 3 ] can be understood.

[0048] (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 (dry state) is measured as Ca(s) [ppm], the calcium content Sca in the soil particles (dry state) of S [g] is calculated by the following formula (2).

[0049] Sca = S × C a (s) (2)

[0050] (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.

[0051] Next, the mass of the collected unconsolidated sample is measured, and then it is dried and pulverized. As with soil samples, any equipment such as a heat-drying moisture meter or a microwave oven can be used to dry the unconsolidated sample. A mill or the like can be used to pulverize the unconsolidated sample. The time required for drying, pulverization, and calcium measurement using a microwave oven or the like 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 specimen for the uniaxial compression test (approximately 3 to 7 days).

[0052] Next, the calcium concentration in the dried and crushed unconsolidated sample (i.e., dry soil cement) is measured using an X-ray fluorescence analyzer. Since the unconsolidated sample is dried and crushed, the cement component and the on-site generated soil component are mixed uniformly, allowing the calcium content to be measured with high accuracy.

[0053] 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 equation (3).

[0054] Cca+Sca=(C+S)×Ca(sc) ···(3)

[0055] The mass of the dried unconsolidated sample is measured before crushing. The water content of the soil cement (before drying) We is calculated from the mass of the unconsolidated sample before drying and the mass of the unconsolidated sample after drying as follows:

[0056] We=(mass before drying - mass after drying) / mass after drying

[0057] (Mass ratio of cement to soil particles (dry state) in soil cement)

[0058] The calcium concentration in soil cement, Ca(sc), is expressed by the following equation (4) from equations (1), (2), and (3).

[0059] Ca(sc)=[C×Ca(c)+S×Ca(s)] / (C+S) ···(4)

[0060] Furthermore, as shown in FIG. 3, 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).

[0061] α = S / C (5-1)

[0062] Using the Ca(c), Ca(s), and Ca(sc) measured as above, the formula (5-1) showing the mass ratio α can be transformed into the following formula (5-2): The mass ratio α is calculated using this formula (5-2).

[0063] α=[Ca(c)-Ca(sc)] / [Ca(sc)-Ca(s)] ···(5-2)

[0064] (Unit volume mass of soil cement) If the mass of water contained in soil cement is W [g], W can be expressed by the following equation (6) using the water content We.

[0065] W = (C + S) · We · (6)

[0066] The mass ratio Rc of cement contained in soil cement is expressed by the following equation (7-1).

[0067] Rc = C / (S + C + W) (7-1)

[0068] This formula (7-1) can be transformed into the following formula (7-2) by using formulas (5-1) and (6). By substituting the calculated water content We and mass ratio α into this formula (7-2), the cement mass ratio Rc can be calculated.

[0069] Rc=[1 / (1+We)]×[1 / (α+1)] ···(7-2)

[0070] Similarly, the mass ratio Rs of soil contained in soil cement is expressed by the following equation (8-1).

[0071] Rs = S / (S + C + W) (8-1)

[0072] This formula (8-1) can be transformed into the following formula (8-2) by using formulas (5-1) and (6). By substituting the calculated water content We and mass ratio α into this formula (8-2), the soil mass ratio Rs can be calculated.

[0073] Rs=[1 / (1+We)]×[α / (α+1)] ···(8-2)

[0074] Similarly, the mass ratio Rw of water contained in soil cement is expressed by the following equation (9-1).

[0075] Rw = W / (S + C + W) (9-1)

[0076] This formula (9-1) can be transformed into the following formula (9-2) by using formulas (5-1) and (6). By substituting the calculated water content ratio We into this formula (9-2), the water mass ratio Rw can be calculated.

[0077] Rw = We / (1 + We) (9 - 2)

[0078] Here, the unit mass of soil cement γsc [g / cm 3 ] is expressed by the following equation (10) using Rc, Rs, and Rw.

[0079] γsc=1 / [(Rc / ρc)+(Rs / ρs)+(Rw)] ···(10)

[0080] In this equation (10), the cement density ρc [g / cm 3], density of soil particles (dry state) ρs [g / cm 3 ], (7-2), (8-2) and (9-2) are substituted to obtain the unit volume mass of soil cement γsc [g / cm 3 ] is calculated.

[0081] (Cement milk replacement rate in soil cement) The cement milk replacement rate Vh is the ratio of the volume of cement milk to the unit volume of soil cement. Therefore, the unit volume mass of soil cement γsc [g / cm 3 ] is the cement milk replacement rate Vh, the unit volume mass of cement milk γc [g / cm 3 ] and the unit volume mass γs [g / cm 3 ] is used to obtain the following formula (11). This formula (11) is added to the γsc [g / cm 3 ] is used to calculate the cement milk replacement rate Vh.

[0082] γsc=γc×Vh+γs×(1-Vh) (11)

[0083] (Estimation of soil-cement strength) Next, the soil cement strength (unconfined compressive strength) is estimated from the correlation data between the cement milk replacement rate Vh and compressive strength shown in Figure 2. Specifically, the unconfined compressive strength value corresponding to the calculated cement milk replacement rate Vh on the approximation line C1 is estimated as the soil cement strength. This allows the unconfined compressive strength of the soil cement sample to be estimated when it is solidified.

[0084] (Action and Effects) In the method for estimating the unit volume mass of soil cement according to an embodiment of the present invention, the mass ratio α of soil to cement in the soil cement is calculated using the calcium content Ca(sc) of a specified element in the measured unconsolidated sample, the calcium content Ca(s) of the soil generated at the site, and the calcium content Ca(c) of the cement used in the cement milk [Equation (5-2)].

[0085] Furthermore, the unit volume mass of soil cement γsc is calculated from the calculated mass ratio α, the soil particle density ρs of the on-site soil, the cement density ρc, and the water content of the soil cement We [Equations (7-2), (8-2), (9-2), and (10)].

[0086] In this way, the method for estimating the unit mass of soil cement according to the present embodiment can estimate the unit mass of soil cement by calculation. Therefore, there is little variation due to manual measurement. In addition, the strength of the soil cement can be estimated without ensuring a curing period until the soil cement hardens.

[0087] 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.

[0088] 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 cement milk mixture to inject into the permanent piles.

[0089] In addition, the amount of cement milk injected into the foot protection section can be reduced compared to the case where the strength of the foot protection section is ensured by sufficiently increasing the injection rate of cement milk (amount of cement milk injected / for example, amount of excavation of the foot protection section), while omitting the compressive strength test. This allows for reduction in material costs.

[0090] Furthermore, according to the method for estimating unit volume mass of soil cement according to an embodiment of the present invention, the cement milk replacement rate Vh can be easily calculated using the estimated unit volume mass γsc of the soil cement.

[0091] In contrast, the cement milk replacement rate Vh can be calculated using the water-cement ratio in the cement milk and the moisture content of the soil sample (for example, JP 2022-184338 A). However, according to the present invention, instead of the water-cement ratio in the cement milk and the moisture content of the soil sample, it is sufficient to measure the moisture content We of the soil cement, so there are fewer objects to be measured.

[0092] Furthermore, according to the method for estimating unit volume mass of soil cement according to an embodiment of the present invention, the unit volume mass of soil cement and the cement milk replacement rate can be accurately estimated on-site in a short time using a simple method.

[0093] In contrast, a conventional method for estimating the mix proportion of concrete is, for example, to heat the concrete to 110°C, 600°C, 1000°C, etc., and 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.

[0094] Another example of a conventional method for estimating the mix ratio of concrete is to analyze the calcium oxide in the solution obtained by dissolving and filtering concrete in acid, and then calculate the amount of cement from the residue to determine the amount of aggregate. This type of chemical analysis requires specialized knowledge, so there are limited personnel who can perform the work. In addition, calcium components in shells and other materials may dissolve in the acid, resulting in an overestimation of the amount of cement, making it difficult to use this method on sea sand, etc.

[0095] (Other embodiments) In the above embodiment, the unit volume mass of the soil cement is estimated in order to estimate the strength of the soil cement, but the estimated unit volume mass of the soil cement can also be used for other purposes.

[0096] For example, the estimated unit mass of soil cement can be used to understand the mixing properties of a ground improvement body formed by mechanical mixing or high-pressure injection mixing of soil cement. When mixing properties are poor, the estimated unit mass is likely to vary among multiple unconsolidated samples. In addition, the deviation between the theoretical unit mass and the estimated unit mass becomes large.

[0097] In the above embodiment, the cement milk replacement rate is calculated from the unit volume mass of the soil cement, and then the strength of the soil cement is estimated, but the embodiment of the present invention is not limited to this. For example, it is not necessary to estimate the strength of the soil cement after calculating the cement milk replacement rate.

[0098] For example, the soil cement 12 forming the foot protection section shown in Fig. 1 is applied by injecting cement milk at a predetermined volume ratio to the volume of the foot protection section. Then, unconsolidated soil cement is collected as an unconsolidated sample, and the cement milk replacement rate is calculated 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 foot protection section.

[0099] In the above embodiment, calcium is used as the predetermined element, but the embodiment of the present invention is not limited to this. Other elements may be used as long as they are contained in the on-site generated soil and cement milk and the concentration of which can be measured using an X-ray fluorescence analyzer. In this way, the present invention can be embodied in various forms. [Explanation of symbols]

[0100] 12 Soil Cement

Claims

1. 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 predetermined element content of the unconsolidated sample, the predetermined element content of the on-site generated soil, and the predetermined element content of the cement used in the cement milk; A step of calculating a unit volume mass of the soil cement from the calculated mass ratio, the soil particle density of the on-site generated soil, the density of the cement, and the water content of the soil cement; A method for estimating unit volume mass of soil cement comprising:

2. The method for estimating unit volume mass of soil cement according to claim 1 , 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 an X-ray fluorescence analyzer.

3. The method for estimating unit volume mass of soil cement according to claim 1 , wherein the soil cement forms a base protection portion of a pile hole.

4. Calculating the ratio of cement milk in the soil cement from the unit volume mass of the soil cement calculated by the method for estimating unit volume mass of soil cement according to any one of claims 1 to 3; Estimating the compressive strength of the soil cement using correlation data between the proportion of cement milk in the soil cement and the compressive strength; Method for estimating soil-cement strength.

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