Quality control methods and construction specification determination methods for high-pressure jet agitation.

Abstract

This invention provides a quality control method that allows for simple and accurate assessment of the quality of improved soil bodies created using high-pressure injection mixing. [Solution] The present invention provides a quality control method for managing the quality of an improved soil body in a high-pressure injection mixing method, which involves injecting a solidifying agent slurry into the ground to create an improved soil body. In this method, additives such as food coloring are pre-mixed into the solidifying agent slurry, and the excess sludge discharged to the surface during construction is collected. The amount of the additive contained in the sludge is then determined using an analytical device such as a spectrophotometer. Furthermore, the amount of solidifying agent to be contained in the improved soil body is determined based on the determined additive content in the sludge. Thus, in this invention, the amount of solidifying agent can be directly and quantitatively determined using an additive that is not affected by the properties of the soil as an indicator, dramatically improving the reliability of quality control. In addition, since the installation of measuring tubes and the like are unnecessary, labor and costs can be reduced.

Description

Technical Field

[0001] The present invention relates to a quality control method for managing the quality of improved bodies formed in ground by the high-pressure jet stirring method, and to a method for determining construction specifications using this quality control method. Background Art

[0002] The high-pressure jet stirring method is a ground improvement method in which high-pressure fluid (a solidifying material slurry mainly composed of cement-based hardening material, water, etc.) is jetted into the ground, and the ground is cut, mixed and stirred to form columnar improved bodies such as cylindrical columns. In this construction method, the solidifying material slurry and air are jetted horizontally from an injection nozzle attached to the tip of an injection pipe inserted into the ground, thereby cutting the ground and mixing and stirring the soil and the solidifying material slurry. For construction, a columnar improved body is generally formed by pulling up the injection pipe inserted into the ground stepwise by several centimeters at fixed time intervals (i.e., stepping up the pipe) while rotating it. An outline of the procedure of the high-pressure jet stirring method is shown in Figure 2.

[0003] <Step a> As shown in Figure 2(a), a construction machine 6 is installed at the center of the formation position of the improved ground body, and an injection pipe 7 is hung by a crane and erected on the construction machine. Then, while discharging drilling water from the tip of the injection pipe 7, the injection pipe 7 is rotated by the construction machine 6 and inserted to the planned depth in the ground.

[0004] <Step b> After inserting the injection pipe 7 to the planned depth, the rotation speed (rpm) and lifting time (s / m) of the injection pipe are set, and injection of the solidifying material slurry is started. As a result, the solidifying material slurry is injected at high pressure from the injection nozzle at the tip of the injection pipe, and the original ground is cut by the strong energy of the jet flow.

[0005] <Step c> By rotating the injection pipe 7 at a set rotation speed, the ground is cut by the jet stream of high-pressure injected solidifying agent slurry, and the raw soil and solidifying agent slurry are forcibly mixed. A portion of the mixture of solidifying agent slurry and raw soil injected into the ground is discharged to the surface as excess (hereinafter referred to as "discharged sludge"). Once the partial construction of the improved body in the first stage is completed, the construction machine is activated to step up the injection pipe in stages to the second stage, third stage, and so on. For example, the step length (length per step) is set to 25 mm, and the number of steps per meter is set to 40 steps. In this way, by rotating the injection pipe at a set speed in each stage, injecting high-pressure solidifying agent slurry from the injection nozzle, and stepping up the injection pipe in stages according to the set lifting time, a roughly cylindrical improved body can be constructed.

[0006] <Process d> After constructing the improved structure within the specified improvement range, the injection pipe 7 is withdrawn to the ground and the inside of the pipe is washed with clean water. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 07-180136 [Patent Document 2] Japanese Patent Publication No. 2015-151687 [Patent Document 3] Japanese Patent Publication No. 2020-007712 [Patent Document 4] Japanese Patent Publication No. 2019-157551 [Overview of the project] [Problems that the invention aims to solve]

[0008] Unlike mechanically agitated ground improvement methods, the high-pressure injection agitation method does not use agitation blades to agitate the ground. Therefore, it is important for quality control to anticipate the final form of the improved ground structure being created.

[0009] Japanese Patent Publication Nos. 07-180136 and 2015-151687 propose a method for physically inspecting the completed structure by installing measuring tubes and using sound and vibration. However, this method requires the measuring tubes to be installed in advance and does not allow measuring equipment to be brought to the site.

[0010] Furthermore, Japanese Patent Publication Nos. 2020-007712 and 2019-157551 propose a method for determining the amount of solidifying agent to be contained in the improved body by measuring the specific gravity and soil particle content of the excavated sludge discharged to the surface. However, with this method, it was difficult to estimate the improvement diameter because the properties and composition of the soil to be improved were not uniform, and the cutting diameter was not uniform depending on the ground strength.

[0011] Therefore, in view of the problems of the conventional technology described above, the object of the present invention is to provide a new quality control method that enables simpler and more accurate assessment of the quality of the improved body produced by the high-pressure injection mixing method, and a method for determining construction specifications using this method. [Means for solving the problem]

[0012] The above objective is a quality control method for managing the quality of an improved body in a high-pressure injection mixing method, which involves injecting a solidifying agent slurry into the ground to create an improved body. The additive is pre-mixed into the aforementioned solidifying agent slurry. A step of collecting the sludge discharged onto the ground as excess during construction and determining the amount of the aforementioned additive contained in the sludge using an analytical device, A step of determining the amount of solidifying agent to be contained in the improved body to be constructed underground, based on the amount of additives in the excavated sludge determined in the above step, This is achieved by a quality control method for high-pressure injection agitation.

[0013] In the process of determining the amount of solidifying agent in the above quality control method, specifically, the amount of solidifying agent to be contained in the improved body is determined by comparing the amount of additives obtained in a pre-tested mix design with the amount of additives contained in the excavated sludge obtained during the actual construction.

[0014] Furthermore, in the process of determining the amount of solidifying agent in the above quality control method, the correlation between the content of additives and the amount of solidifying agent obtained from a mix design test conducted using soil sampled from the ground to be improved prior to the construction of the high-pressure injection mixing method is used.

[0015] Furthermore, the additives used in the above quality control method are substances that do not naturally exist in the ground, and a specific example of such substances is "pigments." When pigments are used as additives, the amount of the additive is determined by measuring the absorbance using a spectrophotometer. In this case, prior to measuring the absorbance, the collected excavated sludge is filtered to separate the liquid components.

[0016] Furthermore, in the above quality control method, the improved diameter of the improved body is determined based on the amount of solidifying agent determined.

[0017] Furthermore, the aforementioned objective is a method for determining the construction specifications of a high-pressure jet agitation method using the above-described quality control method. In the test construction of the high-pressure injection mixing method, the above quality control method is implemented to determine the amount of solidifying agent contained in the improved body created in the ground. Based on the determined amount of solidifying agent, the construction specifications for the main construction of the high-pressure jet agitation method are determined. This is achieved by a method for determining the construction specifications of a high-pressure injection agitation method, characterized by the following: [Effects of the Invention]

[0018] Conventionally, in quality control for the high-pressure jet agitation method, since the properties of the soil to be improved are not uniform, the method using the specific gravity of discharged sludge as an index cannot accurately grasp the amount of solidifying material, and the method of pre-installing measurement pipes has the problem that it requires a great deal of labor and cost. The present invention can directly and quantitatively determine the amount of solidifying material by using an additive that is not affected by soil properties as an index. This eliminates the need for measurement and estimation of the amount of cut soil and the like required in conventional methods, thereby dramatically improving the reliability of quality control, and also eliminates the need for installation of measurement pipes and the like, thus achieving the excellent effect of reducing labor and cost.

[0019] Further, depending on the type of soil such as cohesive soil, there is a concern that the additive may be adsorbed by soil particles, causing errors in measured values. In the present invention, by conducting a mixing test in advance using the actual soil at the construction site, it is possible to establish a site-specific standard for correcting the influence caused by the adsorption rate unique to the soil at the site. That is, the "correlation between the additive content and the amount of solidifying material" that reflects the influence caused by the adsorption rate unique to the soil is obtained in advance. Accordingly, even for soil with a large adsorption influence, the amount of solidifying material can be accurately determined by eliminating the influence, and highly reliable quality control can be realized at sites with various ground conditions.

[0020] Further, the present invention uses a substance that does not naturally exist in the ground as the additive. This eliminates the influence of soil-derived components that interfere with measurement, and allows the analyzer to accurately capture only the additive content, thereby further improving the accuracy of overall quality control.

[0021] Further, the present invention uses a pigment as the additive. This makes it possible to easily and accurately determine the content of the additive by absorbance measurement using a spectrophotometer. As a result, objective and highly reliable data can be stably obtained without requiring special analysis techniques, and the practicality of quality control can be improved.

[0022] Furthermore, in this invention, the content of additives is determined by measuring absorbance using a spectrophotometer. This eliminates subjective judgment by workers and makes it possible to grasp the content as objective and highly accurate numerical data. As a result, the reproducibility and reliability of the measurements are ensured, and the overall accuracy of quality control can be further improved.

[0023] While there are concerns that solid components such as soil particles suspended in the excavated sludge may obstruct light transmission and prevent accurate absorbance measurement, this invention includes a step of filtering the excavated sludge to separate the liquid components prior to measurement, thereby eliminating the influence of solid components that would interfere with the measurement. This enables stable absorbance measurement and further improves the reliability of the overall quality control.

[0024] Conventionally, determining the diameter of the improved body created by high-pressure jet agitation required physical survey methods such as the prior installation of measuring pipes, which were time-consuming and costly. On the other hand, simpler methods using indicators such as the specific gravity of excavated sludge were difficult to accurately determine because the cutting diameter varied depending on the strength of the ground. In contrast, the present invention allows for the quantitative determination of the improved diameter from the determined amount of solidifying material. This achieves the effect of realizing quality control of the finished product without requiring considerable time or cost, and further improving the reliability of the high-pressure jet agitation method.

[0025] Furthermore, according to the present invention, it becomes possible to rationally and accurately determine the construction specifications to be adopted in the actual construction based on objective quality data, such as the amount of solidifying agent obtained from the results of test construction. As a result, the construction quality can be optimized before commencing the actual construction of the high-pressure jet agitation method (the full-scale construction of the improved body), thereby improving the reliability of the high-pressure jet agitation method. [Brief explanation of the drawing]

[0026] [Figure 1] This is a flowchart showing the procedure for calculating the diameter of the planted area in the quality control method according to the present invention. [Figure 2] This is a process diagram showing the construction of the high-pressure jet agitation method. [Modes for carrying out the invention]

[0027] The following describes specific embodiments of the quality control method for high-pressure jet agitation and the method for determining the construction specifications for high-pressure jet agitation.

[0028] (Quality control method for high-pressure jet agitation) First, let's explain the high-pressure jet grouting method. In this method, a high-pressure solidifying agent slurry is injected from a nozzle at the tip of a grout pipe inserted into the ground. This high-pressure injection creates a powerful jet of solidifying agent slurry that cuts into the original ground, forcibly mixing and stirring the original soil with the solidifying agent slurry. The injected solidifying agent slurry is mixed and stirred with the original soil, and most of it remains in the ground as an improved material, but some of it is pushed to the surface as excess along with the original soil. This mixture of solidifying agent slurry and original soil pushed to the surface is called "extruded sludge."

[0029] The solidification slurry used in this embodiment is, for example, a slurry-type ground improvement material mainly composed of a cement-based hardening agent and water. Specifically, a cement slurry prepared by adding water to cement-based materials such as ordinary Portland cement, blast furnace cement, or fly ash cement is commonly used.

[0030] The quality control method of this embodiment is a method for controlling the quality of the improved ground formed by the high-pressure injection mixing method described above. Conventionally, methods that use the specific gravity of the discharged sludge as an indicator have had accuracy problems due to the non-uniformity of the soil properties of the ground. To solve this problem, this embodiment is characterized by pre-mixing additives that do not naturally exist in the ground into the solidification material slurry, and using these additives in the discharged sludge as an indicator to control the quality of the improved ground.

[0031] In this application, "substances that do not naturally exist in the ground" refers to substances that are not contained in the inorganic components of typical ground, such as soil, sand, gravel, clay, and rock, or in the natural organic matter associated with them. Specifically, these are artificially manufactured substances such as food colorings and industrial dyes. The dyes used as additives can be in any form, such as powder, granules, or liquid, and examples include anthocyanin dyes, carotenoid dyes, flavonoid dyes, and gardenia extract. These substances are present at concentrations that are not detectable in a normal ground environment, or are not detectable at all.

[0032] In this embodiment, a dye is used as an example of an additive to be pre-mixed into the solidifying agent slurry. Since the dye is uniformly mixed with the solidifying agent slurry in a fixed ratio during the manufacturing of the solidifying agent slurry, a correlation is established between the amount of solidifying agent contained in the solidifying agent slurry and the amount of dye contained. Therefore, by determining the amount of dye contained by measuring absorbance using a spectrophotometer as described later, it becomes possible to indirectly and accurately determine the amount of solidifying agent contained in the improved body without being affected by soil quality fluctuations, etc.

[0033] The specific steps of the quality control method according to this embodiment will be described below. This method mainly comprises a "step of determining the content of additives" and a "step of determining the amount of solidifying agent".

[0034] First, the sludge discharged to the surface as excess during the construction of the high-pressure jet agitation method is collected. Specifically, samples are taken from the sludge collected in a pit or similar location on the surface at depths where quality control is desired (for example, every 1 meter). Next, the collected sludge is analyzed to determine the amount of additives contained in the sludge. The sludge contains suspended solid components such as soil particles, which obstruct light transmission and hinder accurate measurement. Therefore, in this embodiment, the collected sludge is filtered to separate the liquid components, and the filtrate is used as the analytical sample. For filtration, various filters that can separate liquid and solid components can be used, such as filter paper used in the embodiments described later, porous filters, nonwoven fabrics, and fiber laminated filters. Furthermore, to shorten the filtration time, it is desirable to perform suction filtration or pressure filtration, and for this purpose, electric aspirators, negative pressure pumps, and manual pumps (hand pumps) can be used. Then, a spectrophotometer is used as the analytical instrument, and the absorbance of the filtrate is measured in the wavelength range of, for example, 300 nm to 650 nm to determine the content of additives in the sludge. In the example described later, since food coloring (red) is used as the additive, the absorbance of the filtrate is measured at 525 nm, which is the absorption peak wavelength of food coloring.

[0035] Next, the amount of solidifying agent to be included in the improved body to be constructed underground is determined based on the additive content in the excavated sludge determined in the above process (the additive content determined using the absorbance measured in the above process as an indicator). However, the relationship between the additive content and the amount of solidifying agent may vary depending on the soil type, as will be described later, so a reliable standard to link the two is required in advance. In order to establish such a standard, in this embodiment, a "mix design test" is conducted prior to construction.

[0036] In the mix design test, soil sampled from the site to be improved and a pre-mixed solidifying agent slurry containing the same additives used in construction are employed. Multiple simulated sludge samples are created by varying the mixing ratio of soil to solidifying agent slurry. These samples are filtered to separate the liquid components, similar to the sludge used in construction, and the additive content (absorbance) is measured from the filtrate of each sample. This allows for the establishment of a site-specific standard for the "correlation between additive content and the amount of solidifying agent," reflecting the influence of the soil's inherent properties, such as the adsorption of pigments in cohesive soils. The amount of solidifying agent contained in the improved body is then determined by comparing the additive content (calculated from absorbance) of the sludge obtained in the actual construction with the correlation obtained in the mix design test (i.e., by applying it to an approximate formula showing the correlation).

[0037] Furthermore, the improved diameter of the improved soil can also be determined based on the amount of solidifying agent determined. In high-pressure injection mixing, the amount of solidifying agent injected per unit length is determined by the design. Therefore, by calculating the amount of soil it was mixed with from the measured concentration of the solidifying agent, it is possible to calculate the volume of the improved soil and, consequently, the diameter of the improved soil. In other words, if the determined concentration of the solidifying agent is higher than the design value, it means that the solidifying agent was concentrated in a small area of ​​soil, so the improved diameter can be judged to be narrower than the design. Conversely, if the concentration is low, it means that the solidifying agent was spread thinly over a wide area of ​​soil, so the improved diameter can be judged to be wider than the design. This makes it possible to easily understand the shape of the improved soil, which previously could only be confirmed by geophysical exploration, which required considerable time and cost.

[0038] (Specific calculation procedures for quality control) Next, the specific calculation procedure in the quality control method of the present invention will be described.

[0039] This procedure consists of three main steps: "Step 1: Pre-mixing," "Step 2: Sludge measurement," and "Step 3: Calculation of construction diameter." Figure 1 shows the overall flow of this procedure.

[0040] Step 1: Pre-mixing In this step, a specific standard is created that is tailored to the soil conditions at the site. This standard is used to accurately calculate the amount of solidifying agent needed from the absorbance measured at the site. First, 3 to 5 levels of laboratory mix design tests are conducted using soil samples taken from the construction site and a solidifying agent slurry pre-mixed with a dye (additive). The amount of solidifying agent used in each sample is known based on a predetermined mixing ratio. Next, each sample is filtered, and the absorbance of the resulting filtrate is measured. In this way, combined data (datasets) are obtained, consisting of known solidification agent amounts and the content of dyes (additives) based on absorbance measurements. These datasets are then subjected to the least squares method or linear interpolation to calculate approximate formulas that show the correlation between the two. <Least Squares Method> JPEG0007913717000001.jpg166150<Linear Interpolation> In this method, two arbitrary points (x0, y0) and (x1, y1) are selected from the dataset obtained from the indoor mix design test, and the linear relationship passing through these two points is used as the approximation formula. As shown in JPEG0007913717000002.jpg76152, the measured data is plotted with the amount of solidifying agent on the horizontal axis and absorbance on the vertical axis, and an approximate formula is calculated using the least squares method or linear interpolation. The specific method for preparing simulated sludge samples and the measurement results in this step will be described in detail in the examples below.

[0041] Step 2: Sludge measurement In this step, the amount of solidifying agent is calculated using the approximate formula calculated in Step 1. The absorbance is measured from the excavated sludge collected on-site. The measured absorbance y is substituted into an approximate formula to calculate the amount of solidifying agent needed. <Least Squares Method> TIFF0007913717000003.tif17139<Linear Interpolation> Next, from the amount of solidifying agent x, the mass M of the solidifying agent slurry sl Calculate. TIFF0007913717000005.tif41139

[0042] Step 3: Calculation of the construction diameter This step involves calculating the improved body diameter (improved diameter), which will serve as an indicator for the final quality evaluation, based on the mass of the solidifying agent slurry calculated in Step 2. First, calculate the volume of the solidifying agent slurry from its mass. Next, the volume of the improved ground is calculated from the volume ratio of the solidifying agent slurry to the existing ground and the amount of solidifying agent slurry injected into the ground. TIFF0007913717000007.tif42146 Finally, the diameter of the construction is calculated from the improved volume. By applying this improved volume to the formula for the volume of a cylinder, the diameter of the construction is calculated quantitatively. In this way, it becomes possible to objectively and quantitatively determine the final diameter of the improved structure from the analysis results of the excavated sludge collected on-site.

[0043] (Method for determining construction specifications for high-pressure jet agitation method) Next, we will explain how to determine the construction specifications for the high-pressure jet agitation method. This method involves performing the aforementioned quality control methods (sediment sampling, filtration, absorbance measurement using a spectrophotometer, and determination of the amount of solidifying agent by applying an approximate formula) in a test construction, and then determining the construction specifications for the main construction based on the results.

[0044] In high-pressure injection mixing, the "construction specifications" are crucial factors in determining the quality of the improved soil body. In particular, variable parameters such as the injection pipe withdrawal time (s / m), rotation speed (rpm), and injection pressure of the solidifying agent slurry (MPa) directly control the range and degree of mixing between the solidifying agent slurry and the soil, and therefore directly affect the quality of the improved soil body, such as its strength and diameter.

[0045] The method for determining the construction specifications in this embodiment involves determining the amount of solidifying agent contained in the improved body created in the ground by implementing the aforementioned quality control method during a test construction of the high-pressure injection mixing method, based on standards established in a prior mix design test. This allows for the acquisition of objective numerical data on the amount of solidifying agent contained in the experimentally created improved body and the improved diameter calculated from it.

[0046] Next, based on the determined amount of solidifying agent, the construction specifications for the main application of the high-pressure injection mixing method are determined. The measurement results obtained from the test application (amount of solidifying agent and improved diameter) are compared with the design values. As a result of this comparison, if, for example, the measured concentration of the solidifying agent is higher than the design value and the improved diameter is deemed insufficient, adjustments such as increasing the withdrawal time or increasing the rotation speed or injection pressure of the improved agent are made to determine the optimal construction specifications to be adopted for the main application. In this way, the above determination method determines the final construction specifications for the main application by optimizing the aforementioned variable parameters based directly on the objective quality data obtained from the test application.

[0047] According to the method for determining the construction specifications of the high-pressure jet agitation method described above, it becomes possible to rationally and accurately determine the construction specifications to be adopted for the actual construction based on objective quality data, such as the amount of solidifying agent obtained from the results of test construction. This makes it possible to optimize the construction quality prior to the full-scale implementation of the improved ground construction work and improve the reliability of the high-pressure jet agitation method.

[0048] The present invention will be described in more detail below with reference to examples. [Examples]

[0049] 1. Experimental Objective The purpose of this experiment is to verify the principle of a new quality control method that involves analyzing the sludge discharged to the surface in high-pressure injection mixing and estimating the quality of the improved ground structure created underground based on the analysis results. Specifically, the experiment will verify whether it is possible to estimate the amount of solidifying agent slurry in the discharged sludge by measuring the amount of additives mixed in the solidifying agent slurry beforehand from the discharged sludge, that is, whether a correlation exists between the amount of additives and the amount of solidifying agent.

[0050] 2. Experiment Details We conducted tests to measure how the content of additives (absorbance) changes when the mixing ratio of additive-containing solidifying agent slurry is varied, using both sandy soil and clayey soil.

[0051] 3.Materials used The solidifying agent used in the experiment was ordinary Portland cement (ordinary precast concrete). Toyoura silica sand and Tochi clay were used as soil materials. These were mixed in the predetermined ratios described later to prepare samples of sandy soil and clayey soil. As an example of an additive, a food coloring was used in this example. Specifically, food coloring (red) [Food Red No. 102 15.0%, Dextrin 85.0%] manufactured by Kyoritsu Foods Co., Ltd. was used.

[0052] 4. Experimental Method The experiment was conducted using the following procedure.

[0053] (1) Preparation of solidification agent slurry After dissolving the food coloring (red), which is an additive, in water, ordinary Portland cement, which is a solidifying agent, was added and stirred with a magnetic stirrer to prepare a solidifying agent slurry.

[0054] (2) Preparation of soil materials For this experiment, sandy soil and cohesive soil were prepared using the following procedure. Preparation of sandy soil: Toyoura silica sand, Tochi clay, and water were mixed by hand in the specified ratio (Toyoura silica sand: 1527g, Tochi clay: 234g, water: 340g) until uniform to prepare sandy soil. Preparation of clayey soil: Clayey soil was prepared by hand-mixing clay and water until uniform, resulting in a water content of 40%.

[0055] (3) Mixing of solidifying agent slurry with soil (creation of a jet sludge model) Next, a predetermined amount of soil material prepared in (2) above and solidification agent slurry prepared in (1) were mixed to create a sample (hereinafter referred to as the "jet sludge model") that simulates the sludge discharged by an actual high-pressure jet agitation method. Specifically, the predetermined amounts of soil material and solidification agent slurry shown in Tables 1 and 2 were mixed by hand using a spoon until they appeared uniform.

[0056] (4) Filtration The jet sludge model prepared in (3) above was filtered using a suction filtration device with 5C filter paper to separate the liquid component, which is the filtrate.

[0057] (5) Measurement of absorbance The filtrate separated in (4) above was subjected to a spectrophotometer, and the absorbance (abs) was measured in the wavelength range of 300 nm to 650 nm.

[0058] 5. Experimental samples using sandy soil The specific composition of each sample used in the experiment with sandy soil (No. 1-1 to 1-6 in Table 1 below) is as follows.

[0059] Sample No. 1-1: Solidifying agent slurry 60% This sample is a mixture of 60 mL of solidifying agent slurry and 40 mL of sandy soil. This solidifying agent slurry was prepared by mixing 45.6 g of ordinary Portland cement and 45.6 g of water with 0.0228 g of food coloring (red) as an additive.

[0060] Sample No. 1-2: 50% solidifying agent slurry This sample is a mixture of 50 mL of solidifying agent slurry and 50 mL of sandy soil. The solidifying agent slurry was prepared by mixing 38.0 g of ordinary Portland cement and 38.0 g of water with 0.0190 g of red food coloring.

[0061] Sample No. 1-3: 40% solidifying agent slurry This sample is a mixture of 40 mL of solidifying agent slurry and 60 mL of sandy soil. The solidifying agent slurry was prepared by mixing 30.4 g of ordinary Portland cement and 30.4 g of water with 0.0152 g of red food coloring.

[0062] Sample No. 1-4: 30% solidifying agent slurry This sample is a mixture of 30 mL of solidifying agent slurry and 70 mL of sandy soil. The solidifying agent slurry was prepared by mixing 22.8 g of ordinary Portland cement and 22.8 g of water with 0.0114 g of red food coloring.

[0063] Sample No. 1-5: 20% solidifying agent slurry This sample is a mixture of 20 mL of solidifying agent slurry and 80 mL of sandy soil. The solidifying agent slurry was prepared by mixing 15.2 g of ordinary Portland cement and 15.2 g of water with 0.0076 g of red food coloring.

[0064] Sample No. 1-6: Solidifying agent slurry 50% (no dye / comparative example) This sample is a solidifying agent slurry with the same formulation as No. 1-2 above, but it is a comparative sample that does not contain the food coloring additive.

[0065] 6. Measurement results in sandy soil The results of the experiment conducted using sandy soil are shown in Table 1 below. As shown in Table 1, as the mixing ratio of the solidifying agent slurry mixed with the soil was increased from 20% (No. 1-5) to 60% (No. 1-1), the absorbance measured at 525 nm, the absorption peak wavelength of the food coloring (red), clearly increased from 0.032 to 0.101, in proportion to the mixing ratio. From this result, it was confirmed that a clear positive correlation exists between the amount of solidifying agent slurry and the absorbance.

[0066] Furthermore, in the comparative sample without added dye (comparative example No. 1-6), the absorbance at 526 nm was 0.003, a value very close to zero. This demonstrates that the measured absorbance does not originate from the soil or cement itself, but accurately reflects the content of the added dye.

[0067] From these results, the fundamental principle of the present invention has been demonstrated: the amount of solidifying agent slurry can be quantitatively determined by measuring the amount of the additive pigment as absorbance.

[0068] 7. Experimental samples using clayey soil Next, the specific composition of each sample (No. 2-1 to 2-4 in Table 2 below) used in the experiments conducted with cohesive soil will be described below.

[0069] Sample No. 2-1: 50% solidifying agent slurry This sample is a mixture of 50 mL of solidifying agent slurry and 50 mL of clayey soil. The solidifying agent slurry was prepared by mixing 38.0 g of ordinary Portland cement and 38.0 g of water with 0.019 g of food coloring (red) as an additive.

[0070] Sample No. 2-2: 40% solidifying agent slurry This sample is a mixture of 40 mL of solidifying agent slurry and 60 mL of clayey soil. The solidifying agent slurry was prepared by mixing 30.4 g of ordinary Portland cement and 30.4 g of water with 0.015 g of red food coloring.

[0071] Sample No. 2-3: 30% solidifying agent slurry This sample is a mixture of 30 mL of solidifying agent slurry and 70 mL of clayey soil. The solidifying agent slurry was prepared by mixing 22.8 g of ordinary Portland cement and 22.8 g of water with 0.011 g of red food coloring.

[0072] Sample No. 2-4: Solidifying agent slurry 50% (no dye / comparative example) This sample has the same formulation as No. 2-1 above, but it is a comparative sample that does not contain the food coloring additive.

[0073] 8. Measurement results in cohesive soils The results of the experiment conducted using cohesive soil are shown in Table 2 below. As shown in Table 2, similar to the case of sandy soil, as the mixing ratio of the solidifying agent slurry mixed with the soil increased from 30% (No. 2-3) to 50% (No. 2-1), the absorbance measured at 525 nm, the absorption peak wavelength of red food coloring, increased from 0.021 to 0.076. From these results, it was confirmed that a positive correlation exists between the amount of solidifying agent slurry and absorbance even when using cohesive soil.

[0074] Furthermore, in the samples without added dye (No. 2-4), which were used for comparison, the absorbance at 525 nm was 0.002, a value very close to zero. This demonstrates that the measured absorbance does not originate from the clay itself, but rather reflects the content of the added dye.

[0075] 9. Discussion From the results of the two experiments described above (measurement results using sandy soil and clayey soil), it was confirmed that a positive correlation exists between the mixing ratio of the solidifying agent slurry in the excavated sludge and the absorbance in both soil types. This demonstrates the effectiveness of the basic principle of the present invention, which is that the amount of solidifying agent slurry in the excavated sludge can be estimated by analyzing the content of the additive pigment.

[0076] On the other hand, a comparison of the experimental results from both methods revealed that even with the same mixing ratio, the absorbance measurements differed depending on the soil type. This suggests that soil properties, such as the adsorption of pigments in cohesive soils, affect the measurement results. From this fact, it is clear that in order to achieve highly accurate quality control, it is desirable to conduct mix design tests that use the actual soil at the construction site and establish standards that reflect the unique properties of that soil, rather than using uniform standards.

[0077] Furthermore, by deriving the "correlation between the amount of additives and the amount of solidifying agent" specific to that site through this mixing test, it becomes possible to apply the aforementioned "specific calculation procedure for quality control" based on that correlation. This allows for the quantitative calculation of the final improved body diameter from the analysis results of the excavated sludge collected at the site (amount of solidifying agent in the excavated sludge).

[0078] Thus, the reliable standards established through mix design tests directly lead to the final determination of construction specifications. Specifically, the quality control method of the present invention is implemented during the test construction phase prior to the main construction to determine the amount of solidifying agent contained in the improved material and the resulting construction diameter. If the results differ from the design values, the construction specifications to be used in the main construction, such as the lifting speed and rotation speed, can be rationally and accurately optimized and finalized based on this objective data.

[0079] In the above embodiment, a food-grade red pigment was used as an example of an additive, but the present invention is not limited to this. The color of the pigment is not limited to red; any color suitable for measurement can be used, such as blue, green, or yellow. Furthermore, the type of pigment is not limited to food-grade pigments; industrial pigments can also be used, as long as they do not affect the quality of the improved product produced. Specifically, other types of pigments such as anthocyanin pigments, carotenoid pigments, flavonoid pigments, and gardenia extracts may be used in various forms such as powder, granules, and liquids. In that case, the measurement of absorbance by spectrophotometer is not limited to the 525 nm wavelength used in this embodiment, but should be appropriately adjusted to the absorption peak wavelength specific to the pigment used.

[0080] [Table 1]

[0081] [Table 2]

Claims

1. A quality control method for managing the quality of an improved body in a high-pressure injection mixing method, which involves injecting a solidifying agent slurry into the ground to create an improved body, Prior to the construction of the high-pressure jet mixing method, a mixing test was conducted using soil collected from the ground to be improved and a solidifying agent slurry mixed with a dye. Multiple simulated sludge samples were created by varying the mixing ratio of the soil and the solidifying agent slurry. The absorbance of the liquid components separated from these multiple simulated sludge samples was measured, and an approximate formula showing the correlation between the absorbance and the amount of solidifying agent was determined. The dye is pre-mixed into the solidifying agent slurry used in the construction of the high-pressure jet agitation method. A step of collecting the sludge discharged onto the ground as excess during construction, separating the liquid component from the sludge, and then measuring the absorbance of the liquid component using an analytical device, The absorbance measured in the above step is applied to the approximate formula showing the correlation determined in the above-mentioned mixing test, thereby determining the amount of solidifying agent contained in the improved body to be created in the ground by converting it from the absorbance; A quality control method for high-pressure injection agitation, characterized by having the following features.

2. Based on the determined amount of the solidifying agent, the improved diameter of the improved body is determined. A quality control method for the high-pressure injection mixing method described in feature 1.

3. A method for determining the construction specifications of a high-pressure jet agitation method using the quality control method described in claim 1, In the test construction of the high-pressure injection mixing method, the above quality control method is implemented to determine the amount of solidifying agent contained in the improved body created in the ground. Based on the determined amount of solidifying agent, the construction specifications for the main construction of the high-pressure jet agitation method are determined. A method for determining the construction specifications of a high-pressure jet agitation method, characterized by the following features.

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