Dust concentration measurement method

Abstract

To propose a dust concentration measurement method for a tunnel capable of simplifying measurement and improving work efficiency.SOLUTION: In a tunnel 1 under construction, the concentration of respirable dust inside the tunnel 1 is measured using measurement devices 3, 3 provided on both sides of a tunnel cross section within a section of 10 m to 50 m from a pit face 2. The measurement device 3 has a sizing device capable of sizing the respirable dust. A value obtained by multiplying a measurement result of the measurement device 3 by a preset coefficient is regarded as the average value of the dust concentration in the section.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for measuring dust concentration inside a tunnel. [Background technology]

[0002] During tunnel construction, dust is generated from excavation work, spraying of shotcrete, drilling holes for installing rock bolts, loading of rubble, etc. Therefore, in order to manage the working environment and prevent health problems, it is necessary to grasp the amount of dust generated inside the tunnel during construction and to install appropriate ventilation equipment. For example, Patent Document 1 discloses a dust measurement method for measuring dust during tunnel construction, in which a space where a flash of light is emitted is photographed and the number of white spot images present in the photographed image is counted. The Ministry of Health, Labour and Welfare has established the "Guidelines for Dust Control in Tunnel Construction Works" to prescribe the setting and measurement methods of dust concentration for the purpose of managing the work environment and preventing health hazards. The "Measurement of dust concentration near the tunnel face" that began on April 1, 2021 as a result of the revision of the "Guidelines for Dust Control in Tunnel Construction Works" stipulates that measuring devices must be installed on both sides of the tunnel cross section at points approximately 10m, 30m, and 50m from the face, and that these six measuring devices must be used to measure the concentration of respirable dust in the air. However, to prevent damage to the measuring device due to the blast or contact with flying rocks, the measuring device needs to be removed during blasting work. Also, in tunnel construction where multiple heavy machinery is moving around in a narrow tunnel, it is desirable to remove the measuring device at times other than when measurements are being taken to prevent contact with the heavy machinery. On the other hand, repeatedly removing and installing the measuring devices installed in six locations is time-consuming, and there is a risk that this will hinder the shortening of the construction period. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. WO2008 / 056444 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to propose a method for measuring dust concentration in a tunnel that enables the simplification of measurement and improvement of work efficiency. [Means for solving the problem]

[0005] In order to solve the above problems, the present invention provides a method for measuring dust concentration in a tunnel under construction, Around 30m The concentration of dust inside the tunnel is measured using two measuring devices installed on both sides of the tunnel cross section, and the value obtained by multiplying the measurement results of the two measuring devices by a preset coefficient is calculated. The section 10m to 50m from the face The concentration of respirable dust in the air is regarded as the average value of the concentration of respirable dust in the air. It is preferable that the measuring device is equipped with a particle size classification device capable of classifying the respirable dust. After careful consideration, the inventors discovered that if the concentration of respirable dust is measured at two locations within the above-mentioned section, the measurement results based on the guidelines (the average value of the concentration of respirable dust at six locations) can be estimated. This dust concentration measurement method can reduce the effort required for installing and removing the measuring device, simplifying the measurement and improving work efficiency. In the dust concentration measurement method, the value obtained by multiplying the measurement result of the measuring device by a preset coefficient is regarded as the average value of the respirable dust concentration within the section. In this case, the coefficient may be calculated using the average value of the respirable dust concentration measured by a total of six measuring devices installed on both sides of the tunnel cross section at points approximately 10m, 30m, and 50m from the tunnel face, and the average value of the respirable dust concentration measured by a total of two measuring devices installed on both sides of the tunnel cross section at a point 30m from the tunnel face. Effect of the Invention

[0006] According to the dust concentration measuring method of the present invention, it is possible to simplify the measurement and improve the work efficiency. [Brief description of the drawings]

[0007] [Figure 1] FIG. 2 is a plan view showing the arrangement of measuring devices inside a tunnel. [Diagram 2] FIG. 1 is a schematic diagram showing a measurement period in a confirmation test. [Diagram 3] FIG. 13 is a perspective view showing the arrangement of measuring devices during a confirmation test. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] In this embodiment, a dust concentration measurement method for measuring the concentration of dust generated during construction of mountain tunnels such as NATM will be described. In this embodiment, the concentration of PM4.0 dust (respirable dust) inside the tunnel is estimated based on the standard of "Measurement of dust concentration near the tunnel face" in the "Guideline on dust control measures in tunnel construction work" of the Ministry of Health, Labor and Welfare. Figure 1 shows the dust concentration measurement situation of this embodiment. As shown in FIG. 1, the dust concentration measurement method of this embodiment involves measuring the concentration of PM4.0 dust inside a tunnel 1 under construction using measuring devices 3, 3 installed on both sides (left and right) of the tunnel cross section approximately 30 m from the tunnel face 2, and multiplying the measured value by 1.1 as a coefficient, and regarding the value as the average dust concentration in the section 10 m to 50 m from the tunnel face 2. In this embodiment, a measuring device equipped with a particle size classification device capable of classifying PM4.0 dust particles is used as the measuring device 3. For example, a dust meter LD-5R type (manufactured by Shibata Scientific Co., Ltd.) may be used as such a measuring device 3. The measuring device 3 may be attached to the tunnel wall via a jig or the like, or may be provided along the tunnel wall via a support member such as a support leg. Here, in the "Guidelines for dust control measures in tunnel construction work," "Measurement of dust concentration near the tunnel face" states that measuring devices 3 are installed on both sides of the tunnel cross section (left and right of the tunnel axis) at points approximately 10 m, 30 m, and 50 m from the tunnel face, and PM4.0 dust concentration is measured at all six points, and the average value is 2.0 mg / m 3 The objective is to: In this embodiment, the average value of the values ​​measured at two locations approximately 30 m from the face is multiplied by 1.1 to be considered as the average concentration measured at all six locations (average concentration measured in accordance with the guidelines).

[0009] According to the dust concentration measurement method of the present embodiment, by measuring the dust concentration at two locations, it is possible to estimate the measurement result based on the guidelines (the average value of the respirable dust concentration at six locations). Therefore, the labor required for installing and removing the measuring device 3, the labor required for operating a large number of measuring devices 3, and the labor required for managing the measurement data can be reduced, so that the measurement can be simplified and the work efficiency can be improved. In addition, even if the measuring device 3 is removed during blasting work to prevent damage to the measuring device 3 due to contact with the blast wave or flying rocks during blasting, the labor required for reinstallation can be reduced. In addition, even if the measuring device 3 is removed during a time period other than the measurement time to prevent contact with heavy machinery, the labor required for installing and removing the measuring device 3 can be reduced.

[0010] The coefficient by which the average measurement value is multiplied may be set appropriately during tunnel construction. The method for setting the coefficient is to first measure the PM4.0 dust concentration using a total of six measuring devices 3 installed on both sides of the tunnel cross section at points approximately 10 m, 30 m, and 50 m from the tunnel face 2, and calculate the average value (average value A). Next, the concentration of PM4.0 dust is measured using a total of two measuring devices 3 installed on both sides of the tunnel cross section within a section of 10 m to 50 m from the face 2 (30 m from the face in this embodiment), and the average value (average value B) is calculated. Then, the coefficient to be multiplied to the average value measured by the two measuring devices 3 is calculated by dividing the average value A by the average value B. The coefficient is set when the tunnel face has advanced a predetermined length (for example, 100 m from the tunnel entrance) after the start of tunnel construction.

[0011] The results of confirmation tests carried out on the dust concentration measuring method of this embodiment will be described below. Table 1 shows the site conditions of the tunnel where the tests were conducted.

[0012] [Table 1]

[0013] An overview of the measurement period is shown in Figure 2. As shown in Figure 2, the measurement device was installed after blasting was completed and removed after the secondary spraying was completed to prevent it from being damaged by the blasting work. In other words, the dust concentration was measured during the work of removing the pile, the primary spraying, erecting the shoring, the secondary spraying, and preparation for the next cycle. In this experiment, different mix proportions of shotcrete were used and dust measurements were carried out. Table 2 shows the mix proportions of the base concrete for the shotcrete, and Table 3 shows the concrete materials. Table 4 also shows the construction time (min) for each work process in one cycle.

[0014] [Table 2]

[0015] [Table 3]

[0016] [Table 4]

[0017] As shown in Fig. 3, measuring devices 3, 3 were installed on both sides (left and right) of the tunnel cross section at about 30 m from the tunnel face 2 toward the tunnel entrance, and the PM4.0 dust concentration was measured. As a comparative example, measuring devices 31 to 36 were installed on both sides of the tunnel cross section at points about 10 m, 30 m, and 50 m from the tunnel face 2, respectively, and the PM4.0 dust concentration was measured. Table 5 shows the measurement results (average value for one cycle) and the comparison between the comparative example and the embodiment.

[0018] [Table 5]

[0019] As shown in Table 5, even if the mix ratio of the sprayed concrete is different, there is no significant difference between the ratios of the Example and the Comparative Example, and it was confirmed that when the average value of the PM4.0 dust concentration measured at approximately 30 m from the face is multiplied by 0.98 to 1.1, it becomes equivalent to the average value of the PM4.0 dust concentration measured at approximately 10 m, 30 m, and 50 m from the face. Therefore, even if the measurement is performed at only two points, the left and right, it was confirmed that the concentration measurement equivalent to that measured at six points can be estimated by multiplying by a specified coefficient.

[0020] Next, a comparison was made between the case where the total dust concentration was measured (Comparative Example) and the case where the PM4.0 dust concentration was measured (Example). The total dust concentration was set to 3.0 mg / m 3 The objective is to: The measuring devices 3, 3 were installed approximately 30 m from the tunnel face (see Figure 3). Table 6 shows the measurement results (average values ​​for one cycle) and the ratio between the comparative example and the embodiment.

[0021] [Table 6]

[0022] As shown in Table 6, even when the mix proportions of the shotcrete were different, the average PM4.0 dust concentration was approximately 0.80 times the average total dust concentration. In this way, it was confirmed that even when the total dust concentration was measured, it was possible to estimate the average PM4.0 dust concentration by multiplying it by a certain coefficient.

[0023] Although an embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and each of the above-described components can be appropriately modified without departing from the spirit of the present invention. For example, in the above embodiment, measuring devices are installed at two locations on both sides of the cross section approximately 30 m from the face, but the installation locations of the measuring devices are not limited to this, and it is desirable to install them at two locations on both sides of the cross section within a range of 10 m to 50 m from the face, preferably at two locations on both sides of the cross section within a range of 20 m to 40 m from the face. In the above embodiment, a measuring device equipped with a particle size classifier capable of classifying respirable dust is used, but the configuration of the measuring device is not limited thereto. In addition, in the above embodiment, respirable dust was measured, but the total dust may be measured at two locations on both sides of the cross section within a range of 10 m to 50 m from the face, and the average of the measured values ​​multiplied by a predetermined coefficient (for example, 0.8) may be used as the average concentration of respirable dust at that location. In addition, in the above embodiment, the measuring device is removed and installed depending on the tunnel construction situation, but the tunnel may be excavated, sprayed, and supports erected while the measuring device is left installed. The cross-sectional shape and dimensions of the tunnel 1 are not limited, and may be determined appropriately depending on the ground conditions and the purpose of the tunnel 1, etc. [Explanation of symbols]

[0024] 1. Tunnel 2. Cutting Edge 3. Measuring Equipment 31~36 Measuring equipment

Claims

1. A dust concentration measurement method, characterized in that, in a tunnel under construction, the concentration of dust inside the tunnel is measured using two measuring devices installed on either side of the tunnel cross section approximately 30 m from the tunnel face, and the measurement results of the two measuring devices are multiplied by a preset coefficient and the result is regarded as the average value of the respirable dust concentration in the section 10 m to 50 m from the tunnel face.

2. 2. The dust concentration measuring method according to claim 1, wherein the measuring device is provided with a particle size classifying device capable of classifying respirable dust.

3. The average values ​​of the respirable dust concentrations measured by six measuring devices installed on both sides of the tunnel cross section at points approximately 10 m, 30 m, and 50 m from the tunnel face, and A dust concentration measurement method as described in claim 1 or claim 2, characterized in that the coefficient is calculated using the average value of the respirable dust concentration measured by a total of two measuring devices installed on both sides of the tunnel cross section at a point 30 m from the tunnel face.

Images