JP2024039130A - Correction method and correction system of moisture content or density - Google Patents

Abstract

To make it possible to accurately measure moisture content or density even for uneven ground.SOLUTION: A correction method of moisture content or density includes: preparation steps S1 to S3 for setting multiple grids that divide a ground to be measured into regular intervals in a state of having no unevenness and one or more dent amounts representing the length perpendicular to the face of each grid, and obtaining each correction value for each combination of grid and dent amount using a radiation behavior simulator on the ground without unevenness; measurement steps S4 and S5 for measuring a shape of unevenness for uneven ground with a scanner, adapting the measured shape of unevenness to each grid, obtaining a numerical value of the length perpendicular to the face of each grid as the dent amount, and calculating an average value of the dent amount for each grid as an average dent amount; and a correction step S6 for acquiring and correcting each correction value corresponding to the average dent amount of each grid.SELECTED DRAWING: Figure 2

Description

The present invention relates to a moisture content or density correction method and correction system.

At earthwork sites, it is necessary to measure the moisture content (including not only the moisture content ratio but also the moisture content and moisture percentage; the same applies below) and density (wet density) of the ground quickly and without contact. For this reason, RI (radioisotope) moisture meters and RI density meters that use radioactive materials are often used for measurement. Hereinafter, anything that includes at least one of an RI moisture meter and an RI density meter will be referred to as an "RI instrument" as appropriate.
The term "moisture content or density" includes at least one of the moisture content and the density.

There are two main types of RI instruments: transmission type and scattering type, and both consist of a radiation source that emits radiation from a built-in radioactive substance and a radiation detector (neutron beam/gamma ray) that detects radiation. has been done. As a radiation source, neutron beams are used in the RI moisture meter, and gamma rays are used in the RI density meter.

Regarding the RI moisture meter, the scattering type RI moisture meter has a neutron beam source as a radiation source and a neutron detector as a radiation detector integrated and placed on the upper surface (plane) of the measurement target. . Cf-252 (californium 252) is generally used as a standard body for radiation sources (neutron sources). A neutron beam is emitted from the radiation source of a scattering type RI moisture meter, and a radiation detector detects the attenuated thermal neutrons generated by colliding with hydrogen nuclei within the measurement target as an electrical signal. The detected signal is received by a control unit (of the control device) connected to the radiation detector of the scattering RI moisture meter. Here, the number of thermal neutrons detected per unit time (counting rate), more specifically, the counting rate ratio obtained by dividing the counting rate of thermal neutrons by the counting rate of the radiation standard body (standard counting rate) is It is known that it is expressed by a function corresponding to the hydrogen content density of the measurement target. Using this function as a calibration formula, the moisture content (unit: %) is calculated by the control unit (of the control device) from the calculated count rate ratio.

On the other hand, in a transmission type RI moisture meter, a neutron source is embedded in the ground that is the object of measurement, and a radiation detector is placed on the upper surface of the ground. The neutron beam emitted from the neutron beam passes through the underground, which is the object of measurement, and reaches the radiation detector.

The scattering type RI moisture meter does not require a radiation source to be buried underground like the transmission type RI moisture meter, and can be placed on the upper surface of the ground to be measured to calculate the moisture content. A scattering type RI moisture meter is used for measurements without contact with the ground.
Unless otherwise specified, an RI moisture meter will be referred to as a "scattering type RI moisture meter" and an RI density meter will be referred to as a "scattering type RI density meter". Hereinafter, an instrument including at least one of a scattering RI moisture meter and a scattering RI density meter will be appropriately referred to as a "scattering RI instrument".

When measuring the moisture content and density of the ground, it is desirable that the upper surface (plane) of the ground to be measured be leveled and flat. If the ground is not flat and uneven (referred to as uneven ground), accurate measurements of moisture content and density cannot be made. In other words, the scattering RI instrument is easily affected by the gap between the uneven ground and the bottom of the scattering RI instrument, making it difficult to measure actual moisture content and density.
In particular, scattering RI density meters are more susceptible to unevenness and gaps than scattering RI moisture meters. Scattering type RI density meters have not been widely used at earthwork sites because the count rate ratios related to water content and density vary greatly even if unevenness of just a few mm occurs.
Therefore, methods (systems) for accurately measuring and correcting moisture content and density even if the ground is uneven are known (for example, JP-A-8-074238, JP-A-2019-127682).

JP-A-8-074238 is equipped with a scattering type fast neutron measurement unit that measures the gap in the ground. Specifically, a scattering-type RI instrument that measures the moisture content and density of the ground, a scattering-type fast neutron measuring unit that measures the gap between the bottom of the moving body and the ground, and These control units are mounted.
The scattering type fast neutron measuring section has a fast neutron detector capable of detecting fast neutrons emitted from a neutron beam source and scattered on a plane of the ground. Fast neutrons emitted from the neutron source of the scattering type RI moisture meter collide with atoms of substances on the plane of the ground and are scattered. The number of fast neutrons detected by a fast neutron detector after scattering depends on the distance traveled by the fast neutrons, and decreases as the distance traveled becomes longer. That is, the counting rate (counting rate ratio) of fast neutrons is expressed as a function corresponding to the depth of the gap.

First, a preparation process is carried out using a moving object on ground with known moisture content and density, without any unevenness. Specifically, the scattering type fast neutron measurement unit is operated while the moving object is moving on smooth ground, and the function between the count rate ratio and the gap depth related to fast neutrons is calculated and saved in the control unit. . Then, the depth of the gap is changed multiple times on a known, uneven ground, and functions related to the moisture content or density of the ground, the count rate ratio, and the depth of the gap are calculated and stored in the control unit.

When the depth of the gap exceeds a certain value, the difference from the actual moisture content, density, and counting rate ratio becomes large. Therefore, this constant value is set as a threshold value in advance in the control section before measurement. Specifically, while moving a mobile object over the ground to be measured, the moisture content or density of the ground, the count rate ratio, and the gap depth are measured and calculated in real time, and the results are determined to determine whether the gap depth is below a threshold value. The control unit determines whether If the depth of the gap is below the threshold, each count rate ratio is used to calculate the water content and density.

In Japanese Unexamined Patent Publication No. 2019-127682, a scanner (3D scanner) is mounted on a moving body instead of a scattering fast neutron measurement unit, and the scanner measures the volume of the gap. A threshold value for the volume of the void is determined in advance in the preparation process, and this threshold value is set in the control unit. The control unit determines whether the volume of the gap is less than or equal to a threshold value, and if it is less than or equal to the threshold value, the ground can be measured. If it is determined that measurement is possible, a scattering RI instrument is used to calculate the moisture content and density using a function from the count rate ratio.

Japanese Patent Application Publication No. 8-074238 JP 2019-127682 Publication

In Japanese Patent Application Laid-Open No. 8-074238, a scattering type fast neutron measuring section measures the depth of the gap. Only when the depth of the gap is below a threshold, the count rate ratio is used to calculate the moisture content and density.
In JP2019-127682A, a scanner measures the volume of the gap. Measurements using a scattering RI instrument are performed only when the volume of the gap is below a threshold.
In both cases, the shape of the uneven ground is determined using numerical data such as the depth or volume of the gap. If the depth or volume of the gap is greater than the threshold, it is determined that the unevenness is large and accurate measurement of moisture content or density is impossible, and the count rate ratio is not adopted or the measurement itself is not performed at all. is performed automatically. Therefore, moisture content and density can be easily obtained on somewhat uneven ground.

However, in the case of heavily uneven ground, it is not possible to obtain accurate moisture content or density.
Further, the selection of the threshold value is not specifically mentioned, and depending on the selection of the threshold value, there is a possibility that accurate moisture content and density cannot be obtained. Therefore, the correction method may not be applied to all types of ground.

An object of the present invention is to provide a method for correcting moisture content or density, which can correct the moisture content or density to a value close to the actual moisture content or density, regardless of the soil quality or uneven shape of the ground to be measured.
Another object of the present invention is to provide a moisture content or density correction system that can correct the moisture content or density to a value close to the actual moisture content or density, regardless of the soil quality or uneven shape of the ground to be measured. .

In order to achieve the above purpose, in the preparation process, a plurality of grids are set on the ground without unevenness, and each grid is recessed to have the amount of depression, thereby setting a virtual unevenness. In the preparation process, a radiation behavior simulator is used to obtain each correction value for each combination of grid and dent amount, and in the measurement process, a scanner is used to obtain the shape of the uneven surface.
That is, according to the present invention according to claim 1, in the method of correcting the moisture content or density of the ground to be measured by a scattering RI instrument, the ground to be measured is divided into regular intervals without unevenness. Set multiple grids and one or more indentations representing the length of each grid in the vertical direction to the surface, and use a radiation behavior simulator on smooth ground to calculate each combination of grids and indentations. The preparation process involves acquiring each of these correction values, measuring the shape of the uneven ground with a scanner, making the measured shape of the uneven ground correspond to each grid, and calculating the vertical length to the surface of each grid. A measurement process in which the numerical value of the depth is acquired as the amount of dent, and the average value of the amount of dent in each grid is calculated as the average amount of dent, and a correction process in which each correction value corresponding to the average amount of dent in each grid is obtained and corrected. It is equipped with.
According to the present invention according to claim 4, there is provided a scattering type RI instrument that measures the water content or density of the ground using radiation, a radiation behavior simulator that simulates the scattering type RI instrument, and a radiation behavior simulator that simulates the uneven shape of the ground. In a moisture content or density correction system that includes at least a scanner to measure, a scattering RI instrument, a radiation behavior simulator, and a scanner connected to each other and a control unit that corrects the moisture content or density of the ground, the control unit The ground is divided into multiple grids at regular intervals, and one or more indentations representing the length perpendicular to the surface of each grid are set. Using a behavior simulator, obtain each correction value for each combination of grid and dent amount, measure the shape of the uneven ground with a scanner, and apply the measured shape of the uneven ground to each grid. The numerical value of the length in the vertical direction to the surface of each grid is obtained as the amount of dent, the average value of the amount of dent of each grid is calculated as the average amount of dent, and each correction value corresponding to the average amount of dent of each grid is calculated. are acquired and corrected.

In the present invention according to claims 1 and 4, a radioactive behavior simulation is performed in a state where there is no unevenness and in a state where virtual unevenness due to the amount of depression is set, and each correction value is obtained for all combinations of grids and amount of depression in the ground to be measured. That is, each correction value represents the magnitude of the effect of the grid and amount of depression on the counting rate ratio (increase/decrease ratio). Next, in the ground to be measured that has actual unevenness, the shape of the unevenness is measured by a scanner, and the average amount of depression for each grid is calculated. Then, each correction value corresponding to the average amount of depression for each grid is obtained, and the final (accumulated) correction value is calculated.
Even in cases where the ground is significantly uneven, the system can measure and correct the amount of water without setting a threshold for the amount of depression, and regardless of the soil quality of the ground being measured or the shape of the unevenness. This allows the system to correct the values to be closer to the actual moisture content and density.

1 is a schematic front view of a moisture content or density correction system according to an embodiment of the present invention (a system embodying a moisture content or density correction method according to an embodiment of the present invention); FIG. 1 shows a schematic flow diagram of a method for correcting moisture content or density according to an embodiment of the present invention. Figure 3 shows a detailed flow diagram of a moisture content or density correction method. A detailed flowchart of the entire simulation process of the water content or density correction method is shown. The schematic diagram showing an example of the grid of the ground in a scattering type RI moisture meter is shown. The schematic diagram showing an example of the grid of the ground in a scattering type RI density meter is shown. A schematic diagram showing an example of measurement results of the scanner is shown. A schematic diagram showing an example of the average amount of depression in each grid is shown.

In the correction method for the moisture content or density of the ground to be measured by a scattering RI instrument, the ground to be measured is divided into multiple grids at regular intervals without unevenness, and the vertical direction to the surface of each grid is A preparatory step of setting one or more dent amounts representing the length, and obtaining each correction value for each combination of the grid and the dent amount using a radiation behavior simulator on smooth ground, and a scanner. The shape of the uneven ground is measured using the , the shape of the measured uneven ground corresponds to each grid, the numerical value of the length in the vertical direction to the surface of each grid is obtained as the amount of depression, and the shape of the uneven ground of each grid is measured. The method includes a measuring step of calculating the average value of the amount of dents as the average amount of dents, and a correction step of obtaining and correcting each correction value corresponding to the average amount of dents of each grid.

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a schematic front view of a moisture content or density correction system according to an embodiment of the present invention (a system embodying a moisture content or density correction method according to an embodiment of the present invention). In FIG. 1, for convenience of explanation, the unevenness (unevenness) of the ground 100 is exaggerated.

A moisture content or density correction system 1 (which embodies a moisture content or density correction method) includes a scattering type RI instrument 10 that measures the moisture content or density of the ground 100 using radiation, and a scattering type RI instrument. A simulated radiation behavior simulator 20, a scanner 30 that measures the uneven shape of the ground, and a control unit 40 to which the scattering RI instrument, the radiation behavior simulator, and the scanner are connected and that corrects the moisture content or density of the ground. At least they have it. As shown in FIG. 1, the vertical direction refers to a direction (vertical direction) extending perpendicularly to the plane (upper surface; the same applies to the grid surface described later) of the horizontal ground 100.

The scattering RI instrument 10 includes both a scattering RI moisture meter 10A and a scattering RI density meter 10B, or only one of them. The scattering RI instrument 10 in FIG. 1 is a scattering RI moisture density meter in which the scattering RI moisture meter 10A and the scattering RI density meter 10B are integrated, but the present invention is not limited thereto. The scattering type RI moisture meter 10A and the scattering type RI density meter 10B may not be integrated but may be separated.
Generally, the scattering type RI instrument 10 is configured by integrating a radiation source 12 that emits radiation and a radiation detector 14 that detects the scattered and reflected radiation after being emitted from the radiation source.

The scattering type RI moisture meter 10A includes a radiation source 12A that emits radiation (neutron beam) and a radiation detector that detects thermal neutrons emitted from the radiation source and generated (reflected) by colliding with hydrogen nuclei 100A in the ground. 14A. Californium 252, which emits neutron beams, is used as a standard material for the radiation source 12A, and this radiation source is tightly sealed and stored in the storage section 12A' of the scattering RI moisture meter. In FIG. 1, the wavy lines from the radiation source 12A and the radiation detector 14A represent emitted or reflected radiation (neutron beam).

The scattering type RI density meter 10B includes a radiation source 12B that emits radiation (gamma rays), and a radiation detector 14B that detects the gamma rays that are emitted from the radiation source and are reflected and scattered by the substance 100B in the ground without being absorbed. It is constructed by integrating the. Cobalt 60, cesium 137, etc., which emit gamma rays, are used as a standard material for the radiation source 12B, and this radiation source is tightly sealed and stored in the storage section 12B' of the scattering RI density meter. Similar to the scattering type RI moisture meter 10A, in FIG. 1, the wavy lines from the radiation source 12B and the radiation detector 14B represent emitted or reflected radiation (gamma rays). A shaded area 14B' located between the radiation source 12B and the radiation detector 14B indicates a shield made of a metal with a high atomic number (for example, lead).

The radiation behavior simulator 20 is a radiation behavior measurement and analysis device (simulator) that simulates the scattering RI instrument 10. Examples of methods for measuring or analyzing (simulating) the behavior of neutron beams and γ-rays include, but are not limited to, PHITS (Code) manufactured by the Japan Atomic Energy Agency. Note that PHITS is a Monte Carlo calculation code that simulates various radiation behaviors in all materials using nuclear reaction models, nuclear data, etc.
Since the configuration of the radiation behavior simulator 20, the principle of PHITS, etc. are not essential parts of the present invention, detailed explanation thereof will be omitted.

The scanner 30 is capable of two-dimensionally or three-dimensionally measuring (scanning) the unevenness of the upper surface (plane) of the ground 100, that is, the shape of an uneven surface, in a non-contact manner. For example, a 3D LiDAR using a laser is used as the scanner 30, but a 2D LiDAR may also be used, and the present invention is not limited thereto. During the measurement, the scanner 30 is placed slightly upwardly away from the ground 100 or placed on the plane of the ground.
The scanner 30 outputs the vertical depth (indentation amount) of the unevenness of the ground 100 at each angle around the scanner 30 as numerical data in real time. The amount of depression X refers to, for example, the length from the horizontal plane including the highest peak of the uneven surface, but is not limited thereto.
In addition, in FIG. 1, the radiation behavior simulator 20, the scanner 30, and the scattering type RI instrument 10 are arranged and described in order from the top, but each arrangement is not limited to this. For example, when measuring the uneven shape of the ground 100 with the scanner 30, it goes without saying that other members such as the scattering RI instrument 10 must be evacuated to an appropriate position, and the scanner can also It is placed at the position of

The control unit 40 is connected to the scattering RI instrument 10, the radiation behavior simulator 20, and the scanner 30. A dashed line in FIG. 1 represents an example of a connection between a control device 40', which will be described later, including a control unit 40, a scattering RI instrument 10, a radiation behavior simulator 20, and a scanner 30.
Specifically, the control section 40 is built into a control device 40', and the control device including the control section is controlled by a CPU (processor) 40'-1 having an information processing function. In addition to the control unit 40 that executes various programs, the control device 40' also includes a storage unit 42 that is composed of a storage medium such as a flash memory and stores information, and input means 44' such as a touch panel, keyboard, and buttons. It has an input section 44 that receives input from the computer, an output section 46 that outputs to an output (display) means 46' such as a display, and the like.
Note that the control device 40' may include a communication unit (not shown) that communicates with the outside via a network, and is not limited to this configuration. Furthermore, the program within the control unit 40 may include AI or machine learning.

For example, the storage unit 42 stores a standard count rate for radiation (neutron beams/gamma rays), a function showing the correlation between the count rate ratio and moisture content or density, a moisture content or density correction program (not shown), etc. has been done. Further, numerical data measured by the scattering RI instrument 10, radiation behavior simulator 20, scanner 30, etc., numerical data of each correction value calculated by the control unit 40, etc. are stored.
The control unit 40 calculates a count rate ratio by dividing the measured count rate by the standard count rate stored in the storage unit 42, or calculates water content or density from the function and count rate ratio stored in the storage unit. The integrated correction value, which is the final correction value, is calculated from each correction value stored in the storage unit, and the correction is performed.

FIG. 2 is a schematic flowchart of a method for correcting moisture content or density according to an embodiment of the present invention, and FIG. 3 is a detailed flowchart of the method for correcting moisture content or density.
The control unit 40 sequentially performs the preparation steps S1 to 3, measurement steps S4 and S5, and correction step S6 in FIG. 2 by executing a water content or density correction program (not shown) stored in the storage unit 42. . Preparation steps S1 to S3 are performed on the ground 100 that is not uneven, and measurement steps S4 and S5 are performed on the ground that is uneven.
The preparation steps S1 to S3 each include a simulation preparation step S1, a total simulation step S2, and a correction value calculation step S3, and the measurement steps S4 and 5 each include an unevenness measurement step S4 and an actual measurement step S5.

In order to perform these steps S1 to S6, the control unit 40 uses the method of correcting the moisture content or density of the ground 100, which is the moisture content or density measurement target by the scattering RI instrument 10, to make the ground to be measured uneven. The radiation behavior simulator 20 is used on uneven ground by setting a plurality of grids divided at regular intervals and one or more indentations representing the length of each grid in the vertical direction with respect to the surface. Preparation means 40-1 to 40-3 (simulation preparation step S1 to correction value calculation step S3) that obtain each correction value for each combination of grid and dent amount, respectively, and Measure the shape of the uneven surface, match the measured shape of the uneven surface to each grid, obtain the numerical value of the length in the vertical direction to the surface of each grid as the amount of dent, and average the average value of the amount of dent for each grid. It has a measuring means 40-4 (unevenness measuring step S4) that calculates the amount of dent, and a correcting means 40-6 (correcting step S6) that obtains and corrects each correction value corresponding to the average amount of dent of each grid. and functions as these means (Figures 2 and 3).
More specifically, a simulation is performed in which the counting rate related to the moisture content or density is obtained using the radiation behavior simulator 20 that simulates the scattering RI instrument 10 while the ground 100 that is the target of moisture content or density measurement is in a state of no unevenness. Preparation means 40-1 (simulation preparation step S1), setting a plurality of grids that divide the ground to be measured into regular intervals, and one or more indentations representing the length of each grid in the vertical direction with respect to the surface. All simulating means 40-2 (all simulating means 40-2) for obtaining count rates related to water content or density for all combinations of grids and indentations using the same radiation behavior simulator (as in the simulation preparation step S1). Step S2), divide each counting rate obtained (in the entire simulation step S2) by the counting rate obtained (in the simulation preparation step S1), and calculate the divided value for each combination of the grid and the amount of depression. A correction value calculation means 40-3 (correction value calculation step S3) that obtains each correction value as a correction value, measures the shape of the uneven ground with a scanner, makes the measured shape of the uneven ground correspond to each grid, An unevenness measuring means 40-4 (unevenness measurement step S4) that obtains the numerical value of the length of each grid in the vertical direction with respect to the surface as the amount of depression, and calculates the average value of the amount of depression of each grid as the average amount of depression, ( From each correction value (calculated in correction value calculation step S3), each correction value corresponding to the average amount of depression of each grid (calculated in unevenness measurement step S4) is obtained, and each correction value obtained for each grid is calculated. It has a correction means 40-6 (correction step S6) that corrects all products as an integrated correction value and divides the actually measured count rate ratio by the integrated correction value, and functions as these means (FIGS. 2 and 3). . Note that the actual measurement step S5 is performed by the scattering RI instrument 10 (10A, 10B).

Hereinafter, each step of the moisture content or density correction method performed by the control unit 40 of the moisture content or density correction system 1 (which embodies the moisture content or density correction method) will be mainly described.
1. Description of each process In the preparation process, the radiation behavior simulator 20 is used for the ground 100 without unevenness, and the purpose is to obtain each correction ratio related to water content or density. Specifically, this is performed by a simulation preparation step S1, a full simulation step S2, and a correction value calculation step S3.

1.1 Simulation preparation process S1
In the simulation preparation step S1 performed by the simulation preparation means 40-1, the radiation behavior simulator 20 simulating the scattering type RI instrument 10 is used to measure the moisture content of the ground 100, which is the target of moisture content or density measurement, in an even state. The counting rate related to the amount or density is obtained.

1.2 Whole simulation process S2
In the total simulation process S2 carried out by the total simulation means 40-2, a plurality of grids are used to divide the ground to be measured into regular intervals, and one or more grids are used to represent the depth in the direction perpendicular to the surface of each grid. The amount of concavity is set, and the counting rate related to water content or density is obtained for all combinations of grids and concavity amounts using the same radiation behavior simulator as used in the simulation preparation process.
FIG. 4 shows a detailed flowchart of the entire simulation process of the moisture content or density correction method. FIG. 5 is a schematic diagram showing an example of a ground grid in a scattering type RI moisture meter, and FIG. 6 is a schematic diagram showing an example of a ground grid in a scattering type RI density meter.
The two-dot chain line in FIG. 5 indicates a scattering RI moisture meter 10A that includes a radiation source 12A and a radiation detector 14A placed on the ground 100. The two-dot chain line in FIG. 6 indicates a scattering RI density meter 10B including a radiation source 12B, a radiation detector 14B, and a shield 14B' arranged on the ground 100.

First, the same ground 100 as in the simulation preparation step S1 is divided into a plurality of grids at regular intervals without any unevenness, and one or more grids representing the depth X in the direction perpendicular to the surface of each grid are created. The amount of depression is set (S2-1).
First, the grid will be explained. When the scattering RI instrument 10 is placed on the upper surface (plane) of the ground 100, the grid is a plurality of grids arranged at regular intervals on the surrounding ground that is considered to be affected by the scattering RI instrument (clearance). This refers to each of the divided lattices (Figures 5 and 6). The range of the ground divided into grids is determined by considering the symmetry of radiation around the scattering RI instrument, the influence of the RI instrument, etc.

Specifically, in FIGS. 5 and 6, a range F of 30 cm x 30 cm (hereinafter referred to as "measurement range F") is divided. The size of the grid that is close to the radiation source 12 and the radiation detector 14 is set to be small, and the grid size is set to be larger as the grid moves away from the radiation source 12 and the radiation detector 14. This is because the influence of the clearance becomes stronger as the grid is closer to the radiation source and the radiation detector. Furthermore, in order to shorten the simulation time by the radiation behavior simulator 20, the grids that are far from the radiation source 12 and the radiation detector 14 are set to be large. The numbers attached to the center of each grid in FIGS. 5 and 6 represent the grid numbers assigned in order from 1 to the one closest to the radiation source line 12. Hereinafter, each grid will be explained as "No. n".
In FIG. 1, the scattering type RI moisture meter 10A and the scattering type RI density meter 10B are shown as an integrated unit, but for convenience of explanation, in the following, each case will be divided into the scattering type RI moisture meter 10A and the scattering type RI density meter 10B. I will explain.

In the scattering type RI moisture meter, for example, as shown in FIG. 5, the ground 100 of a measurement range F of 30 cm x 30 cm indicated by a dashed line is divided into 26 pieces symmetrically from front to back and from left to right. That is, as shown in FIG. There are grids from 1 to 26.
The plane size (left-right direction x front-back direction) of the 26 grids in the scattering type RI moisture meter 10A is, for example, No. 1 to 12 are 2cm x 2cm, No. 13 to 22 are 3cm x 3cm, No. 23 is 3cm x 4cm, No. 24 to 26 are 5 cm x 5 cm, but it is not limited to the number or numerical value.

In the scattering type RI densitometer, for example, as shown in FIG. 6, the ground 100 in a measurement range F of 30 cm x 30 cm indicated by a dashed line is divided into 90 pieces symmetrically from front to back. That is, as shown in FIG. There are grids from 1 to 90.
The plane size (front-back direction x left-right direction) of the 90 grids in the scattering RI density meter 10B is No. 1-60 is 1cm x 1cm, No. 61-71 and No. 75 is 2cm x 2cm, No. 72 and no. 76 is 2cm x 3cm, No. 74 and no. 78 is 3cm x 2cm, No. 73 and no. 77 is 3cm x 3cm, No. 79 to 90 is 5 cm x 5 cm, but it is not limited to the number or numerical value.

Next, the amount of depression will be explained. As shown in Figure 1, the amount of depression refers to the depth X in the vertical direction to the surface of each grid (that is, the plane (upper surface) of the ground), and one or more amounts of depression are set for each grid. has been done. The unit of the amount of depression is, for example, millimeter (mm), but is not limited thereto.
Table 1 shows the combinations of grids and indentations in the scattering type RI moisture meter. In Table 1, a represents the number of objects assigned in order from 1, and X represents the amount of depression corresponding to a. As can be seen from Table 1, each grid No. A plurality (a types) of depression amounts X are set for n. If the number of grids and grids is expressed as (n, a), the amount of depression X is uniquely determined by the combination of (n, a).
In addition, each grid No. One (1 way, a=1) dent amount X may be set for n, but since the dent amount X represents a virtual unevenness, multiple dent amounts are set as described later. It can accommodate various sizes and shapes of uneven ground.

To describe in more detail the number a and the amount of dents X, the number a and the amount of dents There is. For example, a grid number located near the radiation source 12A and the radiation detector 14A, or located in the left-right direction on an extension of the line connecting the radiation source and the radiation detector. 1 to 12, eight (eight ways, a=8) dent amounts X are set in Table 1. Moreover, grid No. far from the radiation source 12A and the radiation detector 14A. 13-23, No. For 24 to 26, a small number a of 5 to 4 is set in consideration of the influence of clearance.

Table 2 shows the combinations of grids and depression amounts in the scattering RI densitometer. As shown in Table 2, in the scattering type RI densitometer 10B, the number a and the number of dents also A quantity X is set. For example, a grid number located near the radiation source 12B and the radiation detector 14B, or located in the front-rear direction corresponding to an extension of the line connecting the radiation source and the radiation detector. Ten (10 types, a=10) dent amounts X are set for 1 to 60. Grid No. far from the radiation source 12B and the radiation detector 14B. 61-78 and No. For 79 to 90, a small number a of 7 to 4 is set in consideration of the influence of clearance.
In the scattering type RI moisture meter 10A and the scattering type RI density meter 10B, it goes without saying that the number n of grids, the number a of the setting of the amount of depression in each grid, and the amount of depression X are not limited to these values.

Then, using the same radiation behavior simulator 20 as in the simulation preparation step S1, count rates related to water content or density are obtained for all combinations of grids and indentations (FIG. 4, S2-2 to S2-6). .
As shown in FIG. 4, n=1 and a=1 are set as initial values (S2-2). Referring to Table 1 in the case of a scattering type RI moisture meter and Table 2 in the case of a scattering type RI density meter, in the case of the combination (n, a), No. The n grid is recessed by X mm (S2-3). For example, in the case of a scattering type RI moisture meter, since the amount of depression X at the initial value (n, a) = (1, 1) is 1 mm from Table 1, grid No. 1 is artificially recessed by 1 mm. Next, No. With the n grid recessed by X mm, the radiation behavior is simulated using the same radiation behavior simulator 20 as in the simulation preparation step S1, and the obtained count rate is stored in the control unit 40 (storage unit 42). (S2-4).

If the next a exists, n is unchanged and 1 is added to a (S2-5). If the next a does not exist, the process advances to the next step S2-6. For example, if the initial value (n, a) = (1, 1) in a scattering type RI moisture meter, the following a (a = 2) exists in Table 1, so (n, a) = (1, 2) and returns to S2-3. Since the dent amount X at (n, a)=(1, 2) is 2 mm from Table 1, grid No. 1 is artificially recessed by 2 mm (S2-3), and simulation and storage are performed (S2-4).

By repeating S2-3 to S2-5, grid No. All simulations at n end. That is, if the next a does not exist (S2-5), 1 is added to n, a is returned to the initial value of 1 (S2-6), and the process returns to S2-3. For example, when the initial value (n, a) = (1, 10) in a scattering type RI moisture meter, the following a (a = 11) does not exist in Table 1. Therefore, 1 is added to n, and a is returned to the initial value of 1, and (n, a)=(2, 1), and the process returns to S2-3. The amount of denting X in (n, a) = (2, 1) is 1 mm again from Table 1, so grid No. 2 is artificially recessed by 1 mm (S2-3), and simulation and storage are performed (S2-4).
In this way, in the case of a scattering type RI moisture meter, the amount of artificial depression is set as a virtual unevenness for all the grids listed in Table 1, and the counting rate related to moisture content is simulated by combining these. , and save (S2-2 to S2-6). Similarly, for density, the counting rate related to density is simulated and saved for all combinations listed in Table 2.

1.3 Correction value calculation step S3
In the correction value calculation step S3 performed by the correction value calculation means 40-3, each counting rate obtained in the total simulation step S2 is divided by the counting rate obtained in the simulation preparation step S1, and the divided value is divided into grids. and each correction value t related to each combination of the amount of dent. Let each acquired correction value be t. Each acquired correction value t is stored in the control unit 40 (storage unit 42) for each combination of grid and dent amount.

1.4 Unevenness measurement process S4
In the unevenness measuring step S4 performed by the unevenness measuring means 40-4, the shape of the uneven ground 100 is measured with the scanner 30, and the shape of the measured uneven ground is made to correspond to each grid, and each grid is The numerical value of the length in the direction perpendicular to the surface is obtained as the amount of dent, and the average value of the amount of dent of each grid is calculated as the average amount of dent.
In the unevenness measurement step S4, the uneven ground 100 to be actually measured is measured. First, the scanner 30 measures (scans) the shape of the uneven ground 100 two-dimensionally or three-dimensionally in a non-contact manner, but the measurement results include the vertical depth of the uneven ground. (Indentation amount) X is included as numerical data and is stored in the control section 40 (storage section 42). For example, when a 3D LiDAR is used as the scanner 30, the vertical depth (indentation amount) of the unevenness of the ground 100 is output as numerical data in real time for each angle around the scanner 30.
FIG. 7 shows a schematic diagram representing an example of the measurement results of the scanner. The shape of the unevenness is represented by the scanner 30 as shown in FIG. 7, and the darker the color, the larger the unevenness, that is, the larger (deeper) the depth X is.

Next, the control unit 40 associates the shape of the unevenness measured by the scanner 30 (including the dent amount X, which is numerical data) with the plurality of grids set in the simulation preparation step S1, and Obtained as the amount of dent on the surface. Specifically, each grid consists of a small area such as 1 cm square or 5 cm square, but assuming that the ground to be measured is actually divided into grids, the inside of the grid is not necessarily flat and may have small unevenness due to soil quality etc. There are multiple occurrences. In other words, when it is assumed that the actual ground to be measured is divided into grids, the amount of depression within each grid is not constant (uniform). Therefore, in order to average (uniformize) each grid, the control unit 40 calculates the average value of the amount of depression measured by the scanner 30 in each grid. The average value of the amount of depression in each grid is referred to as the "average amount of depression." The control unit 40 calculates the average amount of depression for each grid, and stores the average amount of depression for each grid.

FIG. 8 shows a schematic diagram representing an example of the average amount of depression in each grid. Referring to Figures 7 and 8 in the case of a scattering type RI density meter, Figure 7 shows the uneven shape of the ground 100 as it is without relying on the grid, but Figure 8 shows Figure 7 corresponding to the grid. , the average amount of dent in each grid is calculated, and each grid is color-coded according to the average amount of dent. Similarly to FIG. 7, the darker the color in FIG. 8, the larger the unevenness (depth; here, the average amount of depression).

1.5 Actual measurement process S5
In the actual measurement step S5 performed by the scattering type RI instrument 10 (10A, 10B), the actual measurement count rate ratio of the moisture content or density by the scattering type RI instrument is calculated on the uneven ground 100 measured in the unevenness measurement step S4. is being obtained. For the purpose of explanation, the term "actual count rate ratio" refers to the count rate ratio (numerical data) of the actual uneven ground 100 to be measured using the scattering RI instrument 10 (10A, 10B). . The actually measured count rate ratio is stored in the control unit 40 (storage unit 42).

1.6 Correction process S6
In the correction step S6 performed by the correction means 40-6, each correction value corresponding to the average dent amount of each grid calculated in the unevenness measurement step S4 is obtained from each correction value t calculated in the correction value calculation step S3. However, the product of all the correction values t obtained for each grid is set as an integrated correction value T, and the actually measured count rate ratio obtained in the actual measurement step S5 is divided by the integrated correction value T for correction. That is, the integrated correction value T becomes the final correction value for correcting the actually measured count rate ratio.
First, the integrated correction value T is calculated using the following equation 1. In the formula, t is each correction value calculated in the correction value calculation step S3, n is the total number of grids, and a is the number of grids assigned in order from 1 as described above.

From the above, the corrected count rate ratio R' is calculated by Equation 2. R in the equation is the count rate ratio before correction, that is, the actual count rate ratio measured in the actual measurement step S5.

2. First verification (using simulator)
Two types of verification (specific examples) were conducted using the moisture content or density correction system 1 (which embodies the moisture content or density correction method) according to the above steps. This will be explained below.
In the first verification, the effect was confirmed by using the ground with known moisture content and density, and by using the radiation behavior simulator 20 instead of the scattering RI instrument 10 in the actual measurement step S5. In the second verification, the scattering type RI instrument 10 was used in the actual measurement step S5. In both verifications, PHITS was used as the simulation method for the radiation behavior simulator 20, and 3DLiDAR was used as the scanner 30.

In the first verification, although the moisture content and density of the ground are known (water content 0.336 g/cm ³ , density 1.750 g/cm ³ ), the radiation behavior simulator 20 is used to simulate the preparation step S1. I did it.
In the entire simulation process S2, approximately 26 pieces for the scattering type RI moisture meter 10A and 90 pieces for the scattering type RI density meter 10B are measured for the measurement range F of 30 cm x 30 cm of the ground 100 in a state without unevenness. (S2-1, Figures 5 and 6). Then, as shown in Tables 1 and 2, the combinations of grids and the amount of depressions The respective rates were obtained (S2-2 to S2-6).
In the correction value calculation step S3, each counting rate obtained in the total simulation step S2 is divided by the counting rate obtained in the simulation preparation step S1, and the divided value is calculated for each correction related to each combination of the grid and the amount of depression. The value t was obtained respectively.

In the unevenness measurement step S4, a plurality of patterns of unevenness are artificially set and created on the ground 100. For example, for the reasons shown in Tables 3 and 4, five patterns of uneven shapes were set and created for both the scattering type RI moisture meter 10A and the scattering type RI moisture meter 10B. In particular, the grids in patterns 4 and 5 of the scattering type RI moisture meter in Table 3 and patterns 3 to 5 of the scattering type RI density meter shown in Table 4 have as large a change in the count rate ratio (that is, each correction value t) as possible. I set it so that

Verification of pattern 1 of the scattering type RI moisture meter 10A in Table 3 will be specifically described below. In pattern 1 of the scattering type RI moisture meter 10A, the amount of depression of all 26 grids is set to 5 mm. The scanner 30 measured the uneven shape (pattern 1 in this case), and the control unit 40 calculated the average amount of depression for each grid in correspondence with each grid (S4).

In the actual measurement step S5, a radiation behavior simulator was used before verification using an actual device (second verification). In the uneven ground 100 measured in the unevenness measurement step S4, here, pattern 1 of the scattering type RI moisture meter 10A in Table 3, the actually measured count rate ratio related to the moisture content was obtained (S5). Then, each correction value t corresponding to the average amount of depression of each grid is obtained, and the product of all the obtained correction values t is set as an integrated correction value T (which is the final correction value) (correction step S6 , see numbers 1 and 2)

Similar steps (unevenness measurement step S4 to correction step S6) were performed for all patterns 2 to 5 of the scattering type RI moisture meter in Table 3 and patterns 1 to 5 of the scattering type RI density meter 10B in Table 4. Ta.
The results of the first verification are shown in Tables 5 and 6 below. In Tables 5 and 6, "counting rate ratio" represents the actually measured counting rate ratio obtained in the actual measurement step S5, and "integrated correction value" represents the cumulative correction value T calculated in the correction step S6.
As shown in Tables 5 and 6, for both the scattering type RI moisture meter and the scattering type RI density meter, there is no large error between the actually measured count rate ratio and the integrated correction value T, and the correction value is close to the actual (actual measurement). It is understood that this has been calculated.

3. Second verification (using actual machine)
A second verification was conducted to confirm the validity of the first verification. In the second verification, a soil tank experiment was conducted using the scattering type RI instrument 10 (actual machine). I will mainly explain the points that are different from the first verification. Note that the order of some steps is different due to the use of the actual machine.
In the second verification, an earthen tank was created by filling a metal mold with dimensions of 60 cm front and back, 60 cm left and right, and 40 cm top and bottom (vertical direction, depth) divided into four layers of mountain sand. Similarly to the first verification, for the measurement range F of 30 cm x 30 cm on the ground 100 of the soil tank, 26 grids were set for the scattering type RI moisture meter 10A, and 90 grids were set for the scattering type RI density meter 10B. Divided.

First, measurements were performed for 5 minutes on the ground 100 of the soil tank in a state where there is no unevenness using the scattering RI density meter 10A and the scattering RI moisture meter 10B (simulation preparation step S1). Next, according to patterns 1 to 3 in Tables 3 and 4, the upper surface of the ground 100 of the earthen tank was concave to create artificial unevenness, and the count rate ratio was calculated (total simulation step S2, correction value calculation Step S3). Then, the shape of the uneven state is measured with the 3DLiDAR (scanner) 30 (unevenness measurement step S4, see FIG. 7), and the shape is measured for 5 minutes using the scattering type RI density meter 10A and the scattering type RI moisture meter 10B. Measurement was performed to obtain the actually measured count rate ratio (actual measurement step S5).

Next, the shape of the unevenness measured by the 3DLiDAR (scanner) 30 was made to correspond to each grid, and the average amount of depression for each grid was calculated (unevenness measurement step S4, see FIG. 8). Then, each correction value t corresponding to the average amount of depression of each grid was obtained, and the integrated correction value T was calculated (correction step S6, see Equations 1 and 2).

The results of the second verification are shown in Tables 7 and 8 below. In Tables 7 and 8, the "correction value" represents the actually measured count rate ratio obtained in the actual measurement step S5, and the "PHITS integrated correction value" represents the integrated correction value T calculated in the correction step S6.
Regarding the scattering type RI densitometer in Table 8, there was one pattern in which the integrated correction value T was larger than the actually measured count rate ratio, that is, it was an overestimation (pattern 3), but the correction values that were generally the same were calculated. I can see that. Regarding the scattering type RI moisture meter in Table 7, it is understood that there is no large error between the actually measured count rate ratio and the integrated correction value T, and a correction value close to the actual (actually measured) value is calculated.

According to the moisture content or density correction system 1 (which embodies the moisture content or density correction method), whether or not measurement is possible is not determined based on whether it is above or below a threshold value, but because it is an artificial, virtual unevenness. The amount of depression is set for each grid, and each correction value t is determined based on the average amount of depression. Each correction value t represents the magnitude of the influence (increase/decrease ratio) that the grid and the amount of depression (unevenness) have on the count rate ratio, so by integrating all the correction values t obtained for each grid, An integrated correction value T, which is the final correction value, is calculated.
That is, by integrating all the correction values t, it is possible to perform area correction that takes into account the effects of unevenness in all grids. Therefore, even if the ground is highly uneven, correction values close to actual measurements can be calculated, and more accurate moisture content and density can be measured and corrected.
The grid represents the position of the virtual unevenness, and the depression amount X represents the depth of the virtual unevenness, so by setting a finer grid and depression amount in the entire simulation process S2, It is possible to correct values close to the actual moisture content and density, regardless of the soil quality or uneven shape.

The above-mentioned embodiments are for illustrating the present invention, and are not intended to limit the present invention in any way, and any modifications, modifications, etc. made within the technical scope of the present invention are also included in the present invention. Needless to say.

For example, as in the second verification, the measurement process performed on uneven ground may be performed before the preparation process performed on uneven ground.
Moreover, as mentioned above, it goes without saying that the moisture content of the ground may be expressed not only by the moisture content ratio but also by the moisture content, moisture content rate, and the like. In the unevenness measurement process, machine learning and AI may be used in the process of making the shape of the measured unevenness correspond to each grid and in the calculation of correction values. Furthermore, as described above, the radiation behavior simulator and scanner are not limited to 3DLiDAR and PHITS, respectively.

INDUSTRIAL APPLICATION This invention can be applied to the correction method and correction system of the moisture content or density of the ground.

1 Moisture content or density correction system 10 Scattering RI instrument 10A Scattering RI moisture meter 10B Scattering RI density meter 20 Radiation behavior simulator 30 Scanner 40 Control section 40-1 Simulation preparation means 40-2 All simulation means 40- 3 Correction value calculation means 40-4 Unevenness measurement means 40-6 Correction means S1 to 3 Preparation process (S1 Simulation preparation process, S2 All simulation process, S3 Correction value calculation process)
S4, 5 measurement process (S4 unevenness measurement process, S5 actual measurement process)
S6 Correction process

Claims (5)

In the method of correcting the moisture content or density of the ground that is the measurement target of the scattering RI instrument,
The ground to be measured is divided into multiple grids at regular intervals without any unevenness, and one or more depressions representing the length in the vertical direction to the surface of each grid are set. a preparation step of obtaining each correction value for each combination of grid and concavity amount using a radiation behavior simulator;
The shape of the uneven ground is measured with a scanner, the measured shape of the uneven ground is made to correspond to each grid, the numerical value of the length in the vertical direction to the surface of each grid is obtained as the amount of dent, and each grid is a measuring step of calculating the average value of the amount of dents as the average amount of dents;
a correction step of obtaining and correcting each correction value corresponding to the average amount of depression of each grid;
A method for correcting moisture content or density, comprising: In the method of correcting the moisture content or density of the ground that is the measurement target of the scattering RI instrument,
The moisture content or density correction method includes a preparation process, a measurement process, and a correction process,
The preparation process includes a simulation preparation process, a full simulation process, and a correction value calculation process, and the measurement process includes an unevenness measurement process and an actual measurement process.
In the simulation preparation process, the count rate related to the moisture content or density is obtained using a radiation behavior simulator that simulates a scattering RI instrument, with the ground to be measured for moisture content or density in a state without unevenness.
The entire simulation process is the same as the simulation preparation process by setting multiple grids that divide the ground to be measured at regular intervals and one or more indentations representing the length of each grid in the vertical direction to the surface. The radiation behavior simulator is used to obtain the count rate related to water content or density for all combinations of grids and indentations, respectively.
In the correction value calculation process, each count rate obtained in all simulation processes is divided by the count rate obtained in the simulation preparation process, and the divided values are used as correction values for each combination of grid and concave amount. Acquired,
In the unevenness measurement process, the shape of the uneven ground is measured with a scanner, the measured shape of the uneven ground is correlated to each grid, and the numerical value of the length in the vertical direction to the surface of each grid is calculated as the amount of depression. , and calculate the average value of the amount of dent for each grid as the average amount of dent,
The actual measurement process is to obtain the actually measured count rate ratio of the moisture content or density using the scattering RI instrument on the uneven ground measured in the unevenness measurement process,
In the correction process, from each correction value calculated in the correction value calculation process, each correction value corresponding to the average dent amount of each grid calculated in the unevenness measurement process is obtained, and all of the correction values obtained for each grid are calculated. A method for correcting moisture content or density, characterized in that the product of is used as an integrated correction value, and the actual measurement count rate ratio obtained in the actual measurement process is divided by the integrated correction value. 3. The method of correcting moisture content or density according to claim 1, wherein the scattering RI instrument comprises both a scattering RI moisture meter and a scattering RI density meter, or only one of them. a scattering RI instrument that uses radiation to measure soil moisture content or density;
A radiation behavior simulator that simulates a scattering RI instrument;
A scanner that measures the shape of uneven ground,
a control unit to which a scattering RI instrument, a radiation behavior simulator, and a scanner are connected and which corrects the moisture content or density of the ground;
In a moisture content or density correction system comprising at least
The control unit is
The ground to be measured is divided into multiple grids at regular intervals without any unevenness, and one or more depressions representing the length in the vertical direction to the surface of each grid are set. Using a radiation behavior simulator, obtain each correction value for each combination of grid and concave amount,
The shape of the uneven ground is measured with a scanner, the measured shape of the uneven ground is made to correspond to each grid, the numerical value of the length in the vertical direction to the surface of each grid is obtained as the amount of dent, and each grid is Calculate the average value of the amount of dents as the average amount of dents,
A water content or density correction system that obtains and corrects each correction value corresponding to the average amount of concavity of each grid. a scattering RI instrument that uses radiation to measure soil moisture content or density;
A radiation behavior simulator that simulates a scattering RI instrument;
A scanner that measures the shape of uneven ground,
a control unit to which a scattering RI instrument, a radiation behavior simulator, and a scanner are connected and which corrects the moisture content or density of the ground;
In a moisture content or density correction system comprising at least
The control section is
Using a radiation behavior simulator that simulates a scattering RI instrument, the ground to be measured for moisture content or density is measured with a radiation behavior simulator that simulates a scattering RI instrument to obtain count rates related to moisture content or density.
Set multiple grids that divide the ground to be measured at regular intervals and one or more depressions representing the length of each grid in the direction perpendicular to the surface, and use the radiation behavior simulator to calculate the combination of all grids and depressions. Obtain the counting rate related to moisture content or density, respectively,
Dividing all the counting rates for all combinations of grids and dent amounts by the counting rates obtained by the radiation behavior simulator, and obtaining the divided values as each correction value for each combination of grids and dent amounts,
Measure the shape of the uneven ground using a two-dimensional or three-dimensional measuring scanner, match the measured shape of the uneven ground to each grid, and calculate the numerical value of the length in the vertical direction to the surface of each grid. is obtained as the amount of dent, and the average value of the amount of dent for each grid is calculated as the average amount of dent,
Obtain the count rate ratio of actual measurements of moisture content or density using a scattering RI instrument on uneven ground,
From each correction value related to each combination of grid and dent amount, each correction value corresponding to the average dent amount of each grid is obtained, and the product of all the correction values obtained for each grid is set as an integrated correction value, and the actual measurement A moisture content or density correction system that corrects the count rate ratio by dividing it by the integrated correction value.

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