Ground improvement method

Abstract

To provide a ground improvement method which can clearly discriminate a place where a cement slurry enters and a place where the cement slurry does not enter.SOLUTION: A ground improvement method for mixing a cement slurry to which a water-soluble fluorescent dye having predetermined concentration is added and soil, and constructing a ground improvement body includes: a first step of irradiating the ground improvement body with black light from a light source; a second step of measuring the ground improvement body irradiated with the black light by the light source by using a measurement instrument; and a third step of comparing a light-emission rate determined on the basis of data output by the measuring instrument with a predetermined threshold, and determining the propriety of a mixed state of the cement slurry.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a ground improvement method for confirming the stirring and mixing state of a ground improvement body when constructing the ground improvement body in the ground.

Background Art

[0002] As a ground improvement method, a deep mixing treatment method is known in which cement slurry is discharged into the ground and stirred and mixed by mechanical stirring to form a ground improvement body in the ground. In such a method, in order to ensure the quality of the ground improvement body, it is necessary that the cement is evenly distributed in the ground improvement body, and it is also necessary to confirm that the cement is evenly distributed in the ground improvement body.

[0003] The amount of cement used in on-site construction is determined by the results of the mix test conducted in the laboratory. Even in this test, it is necessary to confirm that the cement is evenly distributed.

[0004] However, when soil and cement slurry are mixed, as will be described later with reference to FIG. 5, both the soil and the cement slurry are the same color (almost gray), and they cannot be distinguished from each other.

[0005] Therefore, even if a mixture is illuminated with a normal light source such as a fluorescent lamp that emits visible light and observed visually or using equipment such as a camera, it is extremely difficult to determine whether there is uneven mixing or the quality of the mixing state.

[0006] Patent Document 1 (Japanese Patent No. 6944605) proposes a method for confirming the state of a ground improvement body by (1) comparing the image brightness of the ground before improvement taken before improvement with the image brightness taken after improvement, or (2) comparing with a known image of the state of the ground taken in the past.

[0007] However, since black soil and gray cement are to be mixed, the difference in lightness is small, making it difficult to distinguish between them. Also, deep underground, lighting is required, making it difficult to accurately judge the mixing state.

[0008] Moreover, Patent Document 2 (Japanese Patent No. 4886921) discloses a method of injecting a colored curing agent and confirming the degree of mixing in the ground improvement body based on the distribution of the curing agent.

[0009] However, even if a colored curing agent is injected into black soil in this way, as described above, it hardly changes and remains almost black, with an insufficient difference in lightness, making it difficult to distinguish between them. Also, deep underground, lighting is required, making it difficult to accurately judge the mixing state.

[0010] Furthermore, Non-Patent Document 1 (Japan Construction Center, "2018 Edition Design and Quality Control Guidelines for Improved Ground for Buildings") describes a method of observing an alkali reaction (reddish-purple) by spraying a phenolphthalein solution in the inspection of the agitation state.

[0011] The discoloration of phenolphthalein is based on alkaline conditions with pH > 10.0, and it indicates the mixing state of cement on the principle that phenolphthalein discolors at the locations where cement is present.

[0012] Here, the confirmation using phenolphthalein is carried out by utilizing the phenomenon that the locations where the alkaline component cement is present turn reddish-purple.

[0013] However, in reality, the phenolphthalein solution is likely to seep out and drip around, causing discoloration even in locations where it should not originally discolor. As a result, the boundary between the locations where cement is present and where it is not becomes unclear, and there is a problem that the mixing state cannot be appropriately judged.

Patent Document 1

Patent Document 2

Non-Patent Document 1

Disclosure of the Invention

Problems to be Solved by the Invention

[0014] Therefore, an object of the present invention is to provide a ground improvement method capable of clearly distinguishing between a portion containing cement slurry and a portion not containing it.

Means for Solving the Problems

[0015] The ground improvement method according to the first invention is a ground improvement method for constructing a ground improvement body by mixing cement slurry added with a water-soluble fluorescent dye having a predetermined concentration and soil, and includes a first step of irradiating the ground improvement body with black light from a light source, a second step of measuring the ground improvement body irradiated with black light by the light source using a measuring instrument, and a third step of comparing the light emission rate obtained based on the data output by the measuring instrument with a predetermined threshold value to determine the acceptability of the mixing state of the cement slurry.

[0016] Here, when the ground improvement body is irradiated with black light, which is different from visible light, and the ground improvement body irradiated with black light by the light source is measured using a measuring instrument, it becomes possible to clearly distinguish between a portion containing cement slurry and a portion not containing it. Further, based on a clear criterion of comparing the light emission rate obtained based on the data output by the measuring instrument with a predetermined threshold value, the acceptability of the mixing state of the cement slurry is determined. Here, even underground, the water-soluble fluorescent dye irradiated with black light emits light smoothly, and the state can be correctly recognized. Furthermore, the results are not destabilized by complicated processing or disturbing factors.

[0017] Here, the measuring instrument may be a sensor that captures reflected light from the ground improvement body, or may be a camera that captures an image of the ground improvement body.

[0018] The wavelength of the black light is preferably 365 to 405 nanometers. In this way, the light source can be easily secured.

[0019] Preferably, the soil is the soil at the construction site, and the first step, the second step, and the third step are carried out by the boring core collected by boring after the ground improvement body is solidified. Alternatively, the soil is the soil at the construction site, and the first step, the second step, and the third step are carried out in the vertical hole formed by the boring by performing boring with the ground improvement body in a solidified state.

[0020] According to this configuration, it is possible to determine whether the cement slurry is in a mixed state in the implemented ground improvement.

Effects of the Invention

[0021] According to the present invention, it is possible to clearly distinguish between the location where the cement slurry is present and the location where it is not present, and to compare the luminous intensity obtained based on the data output by the measuring instrument with a predetermined threshold value, and to determine whether the cement slurry is in a mixed state based on a clear criterion. Therefore, it is possible to make a determination that is not affected by the shooting situation, the color of the soil, the degree of illumination, etc.

Best Mode for Carrying Out the Invention

[0022] (Embodiment 1) Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a side view of the ground improvement device in Embodiment 1 of the present invention.

[0023] Embodiment 1 relates to the case where a columnar ground improvement body made of soil S is constructed at a relatively deep location by the ground improvement device (column construction machine) shown in FIG. 1.

[0024] As shown in Fig. 1, this ground improvement device includes a base machine 1 that travels on the ground G, a leader 2 that is arranged in front of the base machine 1 and stands vertically during operation, a drive unit 10 that is supported by the leader 2 so as to be movable up and down and includes an actuator such as a motor, a rotating shaft 3 that is given a rotational force by the drive unit 10 and horizontally rotates about a vertical axis in the ground, and an agitation head 4 that is attached to the lower end of the rotating shaft 3.

[0025] The agitation head 4 attached to the tip of the rotating shaft 3 is provided with the following elements. First, at the lower end of the agitation head 4, a digging blade 5 having claws for digging in the ground and for excavating earth and sand is provided, and this digging blade 5 is axially attached to the rotating shaft 3.

[0026] The type of cement can be selected as usual without any problem. Next, a water-soluble fluorescent dye is added to the cement slurry. As the water-soluble fluorescent dye, strontium boron fluoride with a trace amount of europium (SrB4O7F:Eu2+, peak wavelength is 368 - 371 nanometers), barium silicate with a trace amount of lead (BaSi2O5:Pb+, peak wavelength is 350 - 353 nanometers), fluorescein, quinine sulfate, etc. can be preferably used.

[0027] More specifically, it is sufficient to use a commercially available product as the fluorescence leakage inspection agent (for example, Super Glow Fluorescence Leakage Inspection Agent DF-300 (trademark) manufactured by Marktech Co., Ltd., etc.), and the concentration of the fluorescent dye in water may be 0.05 - 20 (%). Usually, it is not necessary to change the water-soluble fluorescent dye depending on the type of cement.

[0028] Next, as shown in Fig. 1, the agitation head 4 of the excavation and agitation device is set to the initial position close to the ground G, the operation of the drive unit 10 is started, and the rotating shaft 3 is rotated. In this way, the digging blade 5 is made to reach the initial depth H1.

[0029] Next, below the initial depth H1, the slurry is discharged from the base of the excavation blade 5, and excavation mixing is performed by the agitation head 4. Here, as described above, unlike normal, a water-soluble fluorescent dye is added to the slurry, so the water-soluble fluorescent dye is similarly mixed into the ground improvement body to be constructed. This state is continued until the target depth H2 (the lowest part of the ground improvement body to be constructed).

[0030] Thereafter, while rotating the agitation head 4, it is raised (pulled up) until it reaches the ground surface, thereby constructing a columnar ground improvement body in the ground using the on-site soil S.

[0031] (Embodiment 2) FIG. 2 is a side view of the ground improvement apparatus according to Embodiment 2 of the present invention.

[0032] Embodiment 2 relates to the case of constructing a flat ground improvement body made of the on-site soil S at a relatively shallow location by the ground improvement apparatus (vertical construction machine) shown in FIG. 2.

[0033] As shown in FIG. 2, this ground improvement apparatus includes a main body 21 that travels on the ground G, and an operating unit 20 that rotates vertically within a vertical plane and discharges cement slurry and agitates it with the soil S.

[0034] The adjustment of the cement and the water-soluble fluorescent dye added thereto are the same as in Embodiment 1.

[0035] In both Embodiments 1 and 2, after constructing the ground improvement body, after it solidifies, a boring core is collected by boring.

[0036] FIG. 3 is a side view of the boring core collection apparatus by boring. Boring is performed after the ground improvement body has solidified to collect a boring core.

[0037] Next, as shown in FIG. 4, the prepared bowling core 35 is placed in the darkroom 31. In the darkroom 31, a light source 6 that irradiates black light and a camera 7 as a measuring instrument that photographs the bowling core 35 irradiated with black light from the light source 6 are arranged. Here, the measuring instrument may be a sensor that captures reflected light from the ground improvement body instead of the camera 7.

[0038] Next, with reference to FIGS. 5 to 8, an actually photographed example will be described. FIG. 5 is an example of a photograph taken using visible light (either a fluorescent lamp or the like may be used, or sunlight itself may be used) without using the light source 6 that irradiates black light in the state of FIG. 4. FIG. 6 is an example of a partially enlarged photograph of FIG. 5. These photographs may be in full color or in grayscale. Characteristically, there is almost no difference in shading throughout the bowling core, and it is difficult to distinguish between light and dark.

[0039] On the other hand, FIG. 7 is a photograph taken in the same manner using black light (wavelength: 365 to 405 nanometers) irradiated by the light source 6 instead of visible light for the same object as in FIG. 6. This photograph may be in full color or in grayscale. Characteristically, throughout the screen, the difference in shading appears more clearly than in FIG. 6, and it is easier to distinguish between light and dark.

[0040] And when the image of FIG. 7 is binarized into black and white, it becomes as shown in FIG. 8. For color reduction, well-known methods such as approximate colors, patterns, and error diffusion methods may be used.

[0041] When using a camera image, since data in a two-dimensional plane is usually obtained, it is desirable to calculate the emission rate (%) in pixel units. That is, in the example of FIG. 8, the total number of pixels A is 184,886 pixels, and the number of white pixels B is 166,460 pixels. Therefore, the emission rate (%) = (A / B) * 100 = (166,460 / 184,886) * 100 = 90 (%).

[0042] As a threshold value for determining the quality of the luminous efficiency (%), TH = 80 (%) is adopted. Needless to say, this numerical value is merely an example, and it must be understood that even when higher or lower threshold values are used, it belongs to the protection scope of the invention of the present application. Therefore, in the above numerical example, when the luminous efficiency is satisfactory, the mixing state is affirmed. That is, the result is that it is sufficiently mixed. On the other hand, if the luminous efficiency is 80 (%) or less, the mixing state is negated.

[0043] That is, as described with reference to FIG. 8, when the total number of pixels is A and the number of white pixels is B, Luminous efficiency (%) = (A / B) * 100 (1) This is sufficient.

[0044] Of course, the above formula is merely an example, and it goes without saying that various different formulas or equivalent formulas can be used as long as the gist of the invention of the present application is not changed.

[0045] (Embodiment 3) In this embodiment, after the boring shown in FIG. 3, the inspection head 14 is inserted into the vertical hole formed by the boring for inspection. FIG. 9(a) is a cross-sectional view of the inspection head in Embodiment 3 of the present invention, and FIG. 9(b) is a cross-sectional view showing the inspection process by the inspection head. A part of the lower part and the side of the inspection head 14 is recessed to form a storage chamber 14a. Inside the storage chamber 14a, a pair of a light source 6 and a measuring instrument 7 are stored horizontally outward. Note that the storage chamber 14a may be configured to open downward. The light source 6 may be any type of fluorescent lamp, incandescent bulb, mercury lamp, or LED that irradiates the ground improvement body with black light (wavelength: 365 to 405 nanometers) in the ground, but the LED is small and easy to use. The measuring instrument 7 may be any of a sensor such as a fluorometer or a camera equipped with an imaging device that measures the ground improvement body irradiated with black light by the light source 6, but here, it is a sensor.

[0046] An opening of the storage chamber 14a is sealed by attaching a transparent or translucent protective cover 14b, thereby protecting the light source 6 and the measuring instrument 7 from the attachment of surrounding earth and sand, slurry, etc. The protective cover 14b can be preferably configured by a resin plate such as acrylic or a plate of tempered glass.

[0047] Now, when the boring is completed, vertical holes are formed in the ground improvement body as described above. As shown in Fig. 9(b), the inspection head 14 is connected to the control computer 16 using the connection cable 15, and the inspection head 14 is inserted into the vertical hole to a predetermined depth. In this state, the light source 6 is turned on and measurement is performed by the measuring instrument 7. Since the processing itself, including the luminous intensity, can be performed in the same manner as described above, further explanation is omitted.

Brief Description of the Drawings

[0048]

Figure 1

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Figure 9

Explanation of Reference Numerals

[0049] 1 Base machine 2 Reader 3 Rotation axis 4 Stirring head 5 Excavation wing 6 Light source 7 Camera 10 Driving unit 14 Inspection head 14a Storage chamber 14b Protective cover 15 Connection cable 16 Control computer 20 Actuating part 21 Main body 31 Darkroom 35 Boring core G Ground S Soil H1 Initial depth H2 Target depth

Claims

1. A ground improvement method for constructing a ground improvement body by mixing soil with a cement slurry to which a water-soluble fluorescent dye of a predetermined concentration has been added, A first step of irradiating the ground improvement body with black light from a light source; A second step of measuring the ground improvement body irradiated with black light by the light source using a measuring instrument; A ground improvement method comprising a third step of comparing the light emission rate calculated based on the data output by the measuring instrument with a predetermined threshold value to determine whether the cement slurry is in a mixed state.

2. 2. The ground improvement method according to claim 1, wherein the measuring instrument is a sensor that captures reflected light from the ground improvement body.

3. 2. The ground improvement method according to claim 1, wherein the measuring instrument is a camera that takes an image of the ground improvement body.

4. 2. The method for improving ground according to claim 1, wherein the wavelength of the black light is 365 to 405 nanometers.

5. The ground improvement method according to claim 1, wherein the soil is soil at a construction site, and the first, second and third steps are carried out using a boring core collected by boring while the ground improvement body is in a solidified state.

6. The ground improvement method according to claim 1, wherein the soil is soil at a construction site, and the first, second and third steps are carried out in a vertical hole formed by boring while the ground improvement body is in a solidified state.

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