How to measure stone content

Abstract

To provide a method for accurately measuring stone content rate of a soil material containing stones, dirt, or the like, without collecting a sample at an actual site.SOLUTION: A method for measuring stone content rate in an observation area includes the steps of: sprinkling water on a slope face in the observation area where a stone content is exposed (S11); photographing the sprayed slope face (S12); and obtaining the stone content rate at the slope face by image processing the photographed picture of the slope face (S14 to S17). The picture to be processed is the picture taken after a predetermined time elapses after the water spray.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for measuring the content of stone contained in soil material that constitutes natural ground. [Background technology]

[0002] Traditionally, when constructing fill dams such as rockfill dams and earth dams, soil materials such as stones and soil extracted by excavating the ground on-site are often used. When constructing a fill dam, the required performance of these soil materials includes permeability (coefficient of hydraulic conductivity) and granularity (distribution of grain size). The debris flow deposits generated by excavation (hereafter referred to as Df material) contain a large amount of stone (coarse stones, boulders) with particle sizes of several tens of centimeters or more, and are used as embankment embankment material. The maximum particle size for impermeable materials is generally 100mm to 200mm, and for semi-permeable materials it is generally around 200mm to 300mm, and any oversized stone exceeding the maximum particle size is discarded. Therefore, in order to satisfy the required quality as an embankment material and ensure the flow capacity of Df material, it is necessary to understand the stone content. However, particle size tests containing stone of 75 mm or more (such as JGS0132; particle size test method for ground materials containing stone) require 5 m per test. 3 Not only was a large amount of sampling required, but there were also problems such as the time and effort required for sieving tests to separate the stones by particle size using a backhoe or by hand, and for measuring the dry mass.

[0003] Therefore, a method has been proposed in which a sample of soil material collected on-site is photographed using a CCD camera or the like, and the photographed image is used to estimate the grain size of the sample (see, for example, Patent Documents 1 and 2). Specifically, the sample is photographed as it is transported on a conveyor belt, the photographed image is then binarized, and the area and number of particles corresponding to the particle size are calculated from the binarized image to determine the particle size distribution of the sample. These methods are said to be capable of determining the particle size distribution with high accuracy in a short time without the need for stone sorting. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-106923 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-83868 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the method of estimating particle size from photographed images of samples collected on site requires that the samples be transported in a separated state (with no overlapping particles) in order to achieve sufficient accuracy, so equipment for separating the particles was required. In addition, the soil material used for the sample was 5 m 3 Not only was it necessary to sample a certain amount of material, but it was also necessary to sample layers at a certain depth in order to cover the heterogeneity in the depth direction, so the sample collection process also required a great deal of time.

[0006] The present invention has been made in view of the problems of the prior art, and aims to provide a method for measuring the stone content with high accuracy without collecting samples on site. [Means for solving the problem]

[0007] After extensive research, the inventors discovered that by taking and analyzing photographs of the slope where the D material is exposed, it is possible to measure the stone content without collecting soil material to be used as a sample, and that by photographing the slope when the stones are dry and the matrix soil is still wet, it is possible to obtain an image with a clear contrast between the stone and the soil, which led to the present invention. In other words, the present invention is a method for measuring the stone content within an observation area, comprising the steps of spraying water on a slope on which stones are exposed within the observation area, photographing the sprayed slope, and performing image processing on the photographed image of the slope to determine the stone content of the slope, wherein the image to be processed is an image taken a predetermined time after watering. This allows the stone content in the observation area to be measured with high accuracy without sampling soil material. Note that it is preferable to set the predetermined time in advance to several stages based on meteorological conditions such as weather and temperature changes (weather forecast information), such as setting it to two hours if it is fine weather and the temperature is 20°C or higher. Furthermore, the image to be processed is an image taken after the specified time has elapsed, with a maximum brightness equal to or greater than a preset threshold (an image in which the soil is still wet and appears black, and the surface of the stone is dry and appears white), so an image with a clear contrast between the stone and the soil can be reliably obtained. Furthermore, since the photographs of the slope were taken using a photographing device mounted on a drone (unmanned aerial vehicle), images of the slope viewed from a direction perpendicular to the slope can be taken easily and in a short time. Furthermore, since the slope is a slope formed at the construction site of a fill dam, such as the slope of a waterway constructed by diversion work on an existing inflowing river, it is possible to cover unevenness in the depth direction. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing a stone content measurement system according to an embodiment of the present invention; [Figure 2] 1 is a flowchart showing a method for measuring the stone content. [Figure 3] 10A and 10B are diagrams showing examples of a photographed image, a binarized image, and an image for analysis after watering. [Figure 4] 1A and 1B are diagrams showing examples of a photographed image, a binarized image, and an image for analysis on a fine day; DETAILED DESCRIPTION OF THE INVENTION

[0009] Figure 1 shows a stone content measuring device (hereinafter referred to as measuring device 10) according to this embodiment. Measuring device 10 is equipped with a CCD camera 11 as an imaging means, a drone 12, an image input means 13, an image judgment means 14, a binary image creation means 15, an image creation means for analysis 16, a stone content calculation means 17, and a display means 18, and estimates the stone content in observation area 1 from an image taken of the slope 3 of an artificial waterway 2 constructed within observation area 1. The means from the image input means 13 to the stone content calculation means 17 constitute an image processing unit 19. In this example, the slope 3 is the slope of an artificial waterway 2 constructed by diversion work of an existing inflow river, as shown by the dashed line in the upper left diagram of the same figure, when constructing a fill dam, but it can be any slope within the construction range of the fill dam. Each of the means constituting the image processing unit 19 functions by causing the CPU of a computer equipped with a CPU as a calculation means, ROM and RAM as storage means, and hardware such as a user interface to operate in accordance with a program stored in the ROM.

[0010] A CCD camera 11 is mounted on a drone 12 and captures an image of the slope 3, which has exposed stone 5 with a matrix of soil 4, from above the slope 3. In this example, the captured image is a color image, but it may also be a monochrome image. The drone 12 is a small unmanned aerial vehicle that includes an aerial vehicle body 12a equipped with a propeller, a camera mounting part 12b for mounting the CCD camera 11, and a camera control part 12c for adjusting the shooting direction of the CCD camera 11 mounted on the aerial vehicle body 12a, and moves the CCD camera 11 into the air above the slope 3 where the shooting takes place. The image input means 13 takes in the image of the slope 3 taken by the CCD camera 11 and sends it to the image determination means 14 . The image determination means 14 determines whether or not the image sent from the image input means 13 is an image that can be used to measure the stone content rate. Hereinafter, an image that can be used to measure the stone content rate will be referred to as an input image. The binary image creating means 15 performs a binary process on the input image to create a binary image. The analysis image creating means 16 creates an analysis image by extracting the contours of the binarized image. The stone content calculation means 17 uses the analysis image to calculate the area ratio R. The calculation of the area ratio R will be described later. The area ratio R corresponds to the stone content of the present invention. The display means 18 includes a display 18G, and displays the calculated stone content on the display 18G.

[0011] Next, the method for measuring the stone content according to the present invention will be described with reference to the flowchart of FIG. First, the photographing date is determined based on weather forecast information, etc., and the artificial waterway 2 and slope 3 to be photographed are determined (step S10). The slope 3 may be any slope that is exposed in the depth direction. A sunny day is desirable for the photographing date, and a high temperature is even better. On the day of photography, first, water is sprinkled on the slope 3 (step S11). Watering can be carried out by a worker using a hose or by letting water flow from the top of the slope 3 towards the bottom of the artificial waterway 2 . Then, after a predetermined time has elapsed since the watering, a drone 12 equipped with a CCD camera 11 is flown into the sky above the artificial waterway 2 determined in step S10, and the surface of the slope 3 is photographed from the front of the slope (perpendicular to the slope 3) (step S12). Next, the image determination means 14 determines whether the captured image is usable (step S13). After a certain amount of time has passed since watering, the soil 4 remains wet and dark, but the surface of the stones 5 dries and becomes whitish (brighter). Therefore, a brightness threshold is set in advance, and if the maximum brightness of the captured image is equal to or greater than the preset threshold, the image is determined to have a clear color contrast between the soil 4 and the stones 5, and this image is sent to the binary image creation means 15 as an input image, and the process proceeds to step S14. On the other hand, if the maximum brightness of the image is less than the preset threshold, it is determined that the surface of the stone 5 is not sufficiently dry, and the process returns to step S12. Note that it is preferable to wait 20 to 30 minutes after returning to step S12 before taking another photograph. In step S14, the input image is binarized to create a binary image. Specifically, a monochrome image is created in which pixels with a brightness below a preset threshold are colored white and pixels with a brightness above the threshold are colored black. Figure 3(a) is an input image of the slope 3 on the east side of the observation area 1, and Figure 3(b) is its binarized image.

[0012] Next, the analysis image creation means 16 performs edge detection on the obtained binary image to create an analysis image as shown in Fig. 3(c), and uses this analysis image to distinguish between the soil 4 and the stones 5 (step S15). In the analysis image, the white parts surrounded by black outlines are the stones 5. Next, the stone content calculation means 17 measures the number of stones 5 and the area S of the stones 5 to calculate the area ratio R, and this area ratio R is set as the stone content (step S16). In this example, the maximum particle size of the waterproof material was set to 150 mm, and the maximum particle size of the semi-permeable material was set to 300 mm to 500 mm, and the area ratio R of stones with a major diameter of 150 mm or more, stones with a major diameter of 300 mm or more, and stones with a major diameter of 500 mm or more was calculated. The area ratio R was calculated using the following formula (1). Area ratio R (%) = (total area of ​​stone) / (area of ​​analysis range) × 100 (1) Finally, the calculated stone content is displayed on the display 18G of the display means 18 in the form of a table, a pie chart, or the like (step S17).

[0013] As mentioned above, Fig. 3(a) is an image (after watering) of the slope (eastern slope) on the east side of observation area 1, Fig. 3(b) is its binarized image, and Fig. 3(c) is the image for analysis. For reference, Figs. 4(a) to (c) show an image (on a clear day) of the slope without watering, the binarized image, and the image for analysis. Table 1 below shows the results of calculating the area ratio R from the image after watering. For comparison, the area ratio R calculated from the image taken on a sunny day is shown on the right. [Table 1] In the image after watering shown in Figure 3(a) above, the boundary between the soil matrix 4 and the stones 5 to be analyzed is clearer than in the image taken on a sunny day shown in Figure 4(a), and so the analysis results also identify a larger number of stones 5 and a larger total area. Therefore, it can be seen that using the image after watering can improve the accuracy of estimating the stone content. In this way, by using the method for measuring the stone content of the present invention, the stone content can be determined without performing excavation work or sieving to collect samples. Therefore, based on the content of large stones that cannot be used as semi-permeable material, it is possible to determine whether the soil material in the observation area 1, including the photographed slope 3, is suitable as a fill material to be used in constructing a fill dam. In addition, since the amount of waste can be determined, the required capacity of the soil dump can be determined in advance.

[0014] Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications and improvements can be made to the above embodiments. It is clear from the claims that such modifications and improvements can also be included within the technical scope of the present invention.

[0015] For example, in the above embodiment, the stone content was calculated using the area ratio R, but the stone content may also be calculated using the major axis as the particle size of the stone 5, as in conventional classification using a sieve. In the above embodiment, the photograph was taken after water was artificially sprayed on the slope 3, but the photograph may also be taken after rain. The time it takes for the stone surface to dry is predicted by the weather forecast before the rain. Furthermore, in the above embodiment, the slope 3 is a slope formed at the construction site of the fill dam, but the slope does not have to be pre-existing, and may be newly formed by cutting the slope at the construction site of the fill dam. In short, it is sufficient if the slope is exposed in the depth direction. Furthermore, cutting work can be completed in less time and effort than the work of collecting samples, so the required time and effort can be significantly reduced compared to conventional methods. [Explanation of symbols]

[0016] 1. Observation area, 2. Artificial waterway, 3. Slope, 4. Soil, 5. Stone, 10 Stone content measurement device, 11 CCD camera, 12 Drone, 13 image input means, 14 image determination means, 15 binary image creation means, 16. Means for creating an image for analysis, 17. Means for calculating stone content, 18. Display means.

Claims

1. A method for measuring the stone content in an observation area, comprising: Spraying water on a slope where rocks are exposed within the observation area; taking an image of the slope surface on which water has been sprayed; a step of image processing the captured image of the slope to determine the stone content of the slope, A method for measuring stone content, characterized in that the image to be processed is an image taken after a predetermined time has elapsed since watering.

2. The method for measuring stone content according to claim 1, characterized in that the image to be processed is an image taken after the specified time has elapsed and whose maximum brightness is equal to or greater than a preset threshold value.

3. The method for measuring stone content according to claim 1 or 2, characterized in that the photograph of the slope is taken by a photographing means mounted on a drone.

4. The method for measuring stone content according to any one of claims 1 to 3, characterized in that the slope is a slope formed at a construction site of a fill dam.

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