Method and system for correcting moisture content or density

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

Technical Field

[0001] The present invention relates to a method and a correction system for correcting moisture content or density.

Background Art

[0002] In a geotechnical site, it is necessary to non-contact and quickly measure the moisture content (including not only the water content ratio but also the water content, moisture content, etc., the same hereinafter) and density (wet density) of the ground. Therefore, RI (radioisotope) moisture meters and RI density meters that use radioactive substances are often used for the measurement. Hereinafter, those including at least one of the RI moisture meter or the RI density meter are appropriately referred to as "RI instruments". Note that the term "moisture content or density" refers to those including at least one of the moisture content or density.

[0003] There are mainly two types of RI instruments: transmission type and scattering type. Both are composed of a radiation source that emits radiation from a built-in radioactive substance and a radiation detector (neutron ray / γ ray) that detects radiation. As the radiation source, neutron rays are used in the RI moisture meter, and γ rays are used in the RI density meter, respectively.

[0004] Regarding RI moisture meters, a scattering-type RI moisture meter integrates a neutron source (radiation source) and a neutron detector (radiation detector) and places them on the upper surface (plane) of the object being measured. Cf-252 (Californium-252) is commonly used as the standard for the radiation source (neutron source). Neutrons are emitted from the radiation source of the scattering-type RI moisture meter, and, roughly speaking, these neutrons collide with hydrogen nuclei in the object being measured, generating and attenuating thermal neutrons which are then detected as an electrical signal by the radiation detector. The detected signal is received by the control unit (control device) connected to the radiation detector of the scattering-type RI moisture meter. Here, it is known that the number of thermal neutrons detected per unit time (counting rate), or more specifically, the counting rate ratio obtained by dividing the thermal neutron counting rate by the counting rate of the radiation standard (standard counting rate), can be expressed as a function corresponding to the hydrogen content density of the object being measured. Using this function as a calibration formula, the control unit (of the control device) calculates the moisture content (in %) from the calculated counting rate ratio.

[0005] On the other hand, in a transmission-type radioisotope moisture meter, the neutron source is embedded in the ground being measured, and a radiation detector is placed on the surface of the ground. The neutrons emitted from the source pass through the ground being measured and reach the radiation detector.

[0006] Unlike transmission-type RI moisture meters, scattering-type RI moisture meters do not require the radiation source to be buried in the ground; they can be placed on the surface of the ground being measured to calculate moisture content. Scattering-type RI moisture meters are used for non-contact measurements of the ground. Unless otherwise specified, RI moisture meters will be referred to as "scattering type RI moisture meters," and RI densimeters as "scattering type RI densimeters." Hereafter, a device that includes at least one of a scattering type RI moisture meter or a scattering type RI densimeter will be appropriately referred to as a "scattering type RI instrument."

[0007] When measuring the moisture content and density of soil, it is desirable that the upper surface (plane) of the soil being measured be leveled and flat. If the surface of the soil is not flat and has irregularities (called unevenness), it is not possible to accurately measure the moisture content and density. In other words, scattering-type radioisotope instruments are susceptible to the influence of the gap between the uneven soil and the bottom surface of the scattering-type radioisotope instrument, making it difficult to measure the actual moisture content and density. Scattering-type radioisotope densimeters are particularly susceptible to unevenness and gaps compared to scattering-type radioisotope moisture meters. Even a few millimeters of unevenness can cause significant variations in the counting rate ratios related to moisture content and density, which is why scattering-type radioisotope densimeters have not been widely used in earthwork sites until now. Therefore, methods (systems) are known for accurately measuring and correcting moisture content and density even if there is unevenness in the ground (for example, Japanese Patent Publication No. Hei 8-074238 and Japanese Patent Publication No. 2019-127682).

[0008] Japanese Patent Publication No. Hei 8-074238 describes a scattering-type fast neutron measuring unit for measuring gaps in the ground. Specifically, a scattering-type radioisotope instrument for measuring the moisture content and density of the ground, a scattering-type fast neutron measuring unit for measuring the gap between the bottom surface of the moving unit and the ground, and a control unit for these are mounted on a mobile body (sled) that moves on the ground. The scattering-type fast neutron measurement unit has a fast neutron detector capable of detecting fast neutrons emitted from a neutron source and scattered on the ground plane. Fast neutrons emitted from the neutron source of the scattering-type RI moisture meter collide with atoms of material on the ground plane and are scattered. The number of fast neutrons detected by the fast neutron detector after scattering depends on the distance traveled by the fast neutrons, decreasing as the distance traveled increases. In other words, the counting rate (counting rate ratio) of fast neutrons can be expressed as a function corresponding to the depth of the gap.

[0009] First, a preparation process is carried out using a mobile unit on a level ground with known moisture content and density. Specifically, the scattering-type fast neutron measurement unit is operated while the mobile unit is moved on the level ground, and a function of the fast neutron counting rate ratio and the void depth is calculated and stored in the control unit. Then, the void depth is changed multiple times on the level ground with known properties, and a function of the ground's moisture content or density, counting rate ratio, and void depth is calculated and stored in the control unit.

[0010] When the void depth exceeds a certain value, the difference between the actual moisture content, density, and counting ratio becomes large. Therefore, this certain value is set as a threshold in the control unit before measurement. Specifically, while moving a mobile device over the ground to be measured, the moisture content or density of the ground, the counting ratio, and the void depth are measured and calculated in real time, and the control unit determines whether the void depth is below the threshold. If the void depth is below the threshold, the respective counting ratios are adopted and the moisture content and density are calculated.

[0011] Japanese Patent Publication No. 2019-127682 describes a system in which a scanner (3D scanner) is mounted on a mobile body instead of a scattering-type fast neutron measuring unit, and the scanner measures the volume of the void. In the preparation step, a threshold value for the void volume is predetermined and set in the control unit. The control unit determines whether the void volume is below the threshold value, and if it is, the ground can be measured. If it is determined that measurement is possible, a scattering-type RI instrument is used to calculate the moisture content and density from the counting rate ratio using a function. [Prior art documents] [Patent Documents]

[0012] [Patent Document 1] Japanese Patent Application Publication No. 8-074238 [Patent Document 2] Japanese Patent Publication No. 2019-127682 [Overview of the project] [Problems that the invention aims to solve]

[0013] Japanese Patent Publication No. Hei 8-074238 describes a scattering-type fast neutron measurement unit that measures the depth of the gap. The counting rate ratio is used only when the gap depth is below a threshold, and the moisture content and density are calculated. Japanese Patent Publication No. 2019-127682 describes a scanner measuring the volume of the gap. Measurement using a scattering-type radioisotope instrument is performed only when the gap volume is below a threshold. In both cases, the shape of the ground unevenness is grasped using numerical data such as the depth or volume of the voids. If the depth or volume of the voids exceeds a threshold, the system automatically determines that the unevenness is significant and that accurate measurement of moisture content and density is impossible, and either does not use the counting ratio or does not perform the measurement at all. Therefore, even in ground with some unevenness, moisture content and density can be easily obtained.

[0014] However, in areas with significant unevenness in the ground, it becomes impossible to obtain accurate moisture content and density measurements. Furthermore, the selection of thresholds is not specifically mentioned, and depending on the threshold chosen, it may not be possible to obtain accurate moisture content and density. Therefore, this correction method may not be applicable to all types of soil.

[0015] The present invention aims to provide a method for correcting moisture content or density that can correct values ​​to be close to the actual moisture content or density, regardless of the soil type or unevenness of the ground being measured. Furthermore, another objective of the present invention is to provide a moisture content or density correction system that can correct values ​​to be close to the actual moisture content or density, regardless of the soil type or unevenness of the ground being measured. [Means for solving the problem]

[0016] To achieve the above objective, in the preparation stage, multiple grids are set up on level ground, and each grid is indented to create a degree of depression, thereby creating a virtual uneven surface. In the preparation stage, a radiation behavior simulator is used to acquire correction values ​​for each combination of grids and depression amounts, and in the measurement stage, a scanner is used to acquire the shape of the uneven surface. In other words, according to the present invention as described in claim 1, In a method for correcting the moisture content or density of ground to be measured by a scattering-type RI instrument, the method for correcting the moisture content or density comprises a preparation step, a measurement step, and a correction step. The preparation step comprises a simulation preparation step, a full simulation step, and a correction value calculation step. The measurement step comprises a leveling step and an actual measurement step. The simulation preparation step involves obtaining a count rate related to the moisture content or density using a radiation behavior simulator that simulates a scattering-type RI instrument, with the ground to be measured in a level state. The full simulation step involves setting multiple grids that divide the ground to be measured into regular intervals and one or more depression amounts representing the length perpendicular to the face of each grid. The same radiation behavior simulator as in the simulation preparation step obtains the count rate related to the moisture content or density for all combinations of grids and depression amounts. The correction value calculation step involves dividing each count rate obtained in the full simulation step by the count rate obtained in the simulation preparation step, and obtaining the resulting values ​​as correction values ​​for each combination of grids and depression amounts. The unevenness measurement process involves measuring the shape of uneven ground using a scanner, associating the measured shape of unevenness with each grid, obtaining the length perpendicular to the surface of each grid as the amount of depression, and calculating the average of the depression amounts for each grid as the average depression amount. The actual measurement process involves obtaining the actual count rate ratio related to moisture content or density using a scattering-type RI instrument for the uneven ground measured in the unevenness measurement process. The correction process involves obtaining each correction value corresponding to the average depression amount for each grid calculated in the unevenness measurement process from each correction value calculated in the correction value calculation process, and using the product of all the correction values ​​obtained for each grid as the cumulative correction value. The actual count rate ratio obtained in the actual measurement process is then corrected by dividing it by the cumulative correction value. Claim 3 According to the present invention relating to this invention, A moisture content or density correction system comprising at least a scattering-type RI instrument for measuring the moisture content or density of the ground using radiation, a radiation behavior simulator that simulates the scattering-type RI instrument, a scanner for measuring the shape of unevenness in the ground, and a control unit connected to the scattering-type RI instrument, the radiation behavior simulator, and the scanner for correcting the moisture content or density of the ground, wherein the control unit obtains a count rate related to the moisture content or density using a radiation behavior simulator that simulates the scattering-type RI instrument, sets up a plurality of grids that divide the ground to be measured into regular intervals, and sets one or more depression amounts representing the length perpendicular to the face of each grid, obtains a count rate related to the moisture content or density for all combinations of grids and depression amounts using the radiation behavior simulator, divides all count rates for all combinations of grids and depression amounts by the count rates obtained from the radiation behavior simulator, and sets the divided values ​​as correction values ​​for each combination of grids and depression amounts. Each of these is acquired, and the shape of the uneven ground is measured using a scanner that measures in two or three dimensions. The measured shape of the unevenness is associated with each grid, and the length perpendicular to the surface of each grid is acquired as the amount of depression. The average value of the depression amounts for each grid is calculated as the average depression amount. For the uneven ground, the actual count rate ratio related to the moisture content or density is acquired using a scattering type RI instrument. From the correction values ​​for each combination of grid and depression amount, each correction value corresponding to the average depression amount for each grid is acquired. The product of all the correction values ​​acquired for each grid is taken as the cumulative correction value, and the actual count rate ratio is corrected by dividing it by the cumulative correction value. [Effects of the Invention]

[0017] Claim 1, 3In the present invention according to the present invention, a radioactive behavior simulation is performed in a state without unevenness and in a state where virtual unevenness is set according to the amount of depression, and each correction value related to all combinations of grids and amounts of depression of the ground to be measured is obtained. That is, each correction value represents the magnitude (increase / decrease ratio) of the influence of the grid and the amount of depression on the counting rate ratio. Next, in the actual uneven ground to be measured, the shape of the unevenness is measured by a scanner, and the average amount of depression of each grid is calculated. Then, each correction value corresponding to the average amount of depression of each grid is obtained, and the final (integrated) correction value is calculated. Even in a ground with large unevenness, measurement and correction can be performed without setting a threshold value for the amount of depression, regardless of the soil quality of the ground to be measured and the shape of the unevenness. Therefore, it is possible to correct to a value close to the actual moisture content and density.

Brief Description of the Drawings

[0018] [Figure 1] 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) is shown. [Figure 2] A schematic flowchart of a moisture content or density correction method according to an embodiment of the present invention is shown. [Figure 3] A detailed flowchart of a moisture content or density correction method is shown. [Figure 4] A detailed flowchart of the entire simulation process in the moisture content or density correction method is shown. [Figure 5] A schematic diagram showing an example of a grid of the ground in a scattered-type RI moisture meter is shown. [Figure 6] A schematic diagram showing an example of a grid of the ground in a scattered-type RI density meter is shown. [Figure 7] A schematic diagram showing an example of the measurement result of a scanner is shown. [Figure 8] A schematic diagram showing an example of the average amount of depression in each grid is shown.

Modes for Carrying Out the Invention

[0019] In a method for correcting the moisture content or density of ground to be measured by a scattering-type RI instrument, the method for correcting the moisture content or density comprises a preparation step, a measurement step, and a correction step. The preparation step comprises a simulation preparation step, a full simulation step, and a correction value calculation step. The measurement step comprises a leveling step and an actual measurement step. The simulation preparation step involves obtaining a count rate related to the moisture content or density using a radiation behavior simulator that simulates a scattering-type RI instrument, with the ground to be measured in a level state. The full simulation step involves setting multiple grids that divide the ground to be measured into regular intervals and one or more depression amounts representing the length perpendicular to the face of each grid. The same radiation behavior simulator as in the simulation preparation step obtains the count rate related to the moisture content or density for all combinations of grids and depression amounts. The correction value calculation step involves dividing each count rate obtained in the full simulation step by the count rate obtained in the simulation preparation step, and obtaining the resulting values ​​as correction values ​​for each combination of grids and depression amounts. The unevenness measurement process involves measuring the shape of uneven ground using a scanner, associating the measured shape of unevenness with each grid, obtaining the length perpendicular to the surface of each grid as the amount of depression, and calculating the average of the depression amounts for each grid as the average depression amount. The actual measurement process involves obtaining the actual count rate ratio related to moisture content or density using a scattering-type RI instrument for the uneven ground measured in the unevenness measurement process. The correction process involves obtaining each correction value corresponding to the average depression amount for each grid calculated in the unevenness measurement process from each correction value calculated in the correction value calculation process, and using the product of all the correction values ​​obtained for each grid as the cumulative correction value. The actual count rate ratio obtained in the actual measurement process is then corrected by dividing it by the cumulative correction value. [Examples]

[0020] The embodiments of the present invention will be described in detail below with reference to the drawings. Figure 1 shows a schematic front view of a moisture content or density correction system according to one embodiment of the present invention (a system that embodies the moisture content or density correction method according to an embodiment of the present invention). In Figure 1, for the sake of explanation, the unevenness (unevenness) of the ground 100 is exaggerated.

[0021] The moisture content or density correction system 1 (which embodies a method for correcting moisture content or density) comprises at least a scattering-type RI instrument 10 that uses radiation to measure the moisture content or density of the ground 100, a radiation behavior simulator 20 that simulates the scattering-type RI instrument, a scanner 30 that measures the shape of unevenness in the ground, and a control unit 40 to which the scattering-type RI instrument, the radiation behavior simulator and the scanner are connected and which corrects the moisture content or density of the ground. As shown in Figure 1, the vertical direction refers to the direction (up and down direction) that extends perpendicular to the plane of the horizontal ground 100 (upper surface; the same applies to the grid surface described later).

[0022] The scattering-type RI instrument 10 may include either a scattering-type RI moisture meter 10A or a scattering-type RI densimeter 10B, or it may include only one of them. The scattering-type RI instrument 10 in Figure 1 is a scattering-type RI moisture densimeter in which the scattering-type RI moisture meter 10A and the scattering-type RI densimeter 10B are integrated, but it is not limited to this. The scattering-type RI moisture meter 10A and the scattering-type RI densimeter 10B may not be integrated and may be separate. In general, the scattering-type RI instrument 10 is composed of an integrated radiation source 12 that emits radiation and a radiation detector 14 that detects radiation that has been scattered and reflected after being emitted from the radiation source.

[0023] The scattering-type RI moisture meter 10A is composed of an integrated radiation source 12A that emits radiation (neutron beams) and a radiation detector 14A that detects thermal neutrons emitted from the radiation source that collide with hydrogen nuclei 100A in the ground and are generated (reflected). Californium-252, which emits neutron beams, is used as a standard for the radiation source 12A, and this radiation source is strictly sealed and stored in the storage section 12A' of the scattering-type RI moisture meter. In Figure 1, the dashed lines from the radiation source 12A and the radiation detector 14A represent the emitted or reflected radiation (neutron beams).

[0024] The scattering-type RI densimeter 10B is composed of an integrated radiation source 12B that emits radiation (gamma rays) and a radiation detector 14B that detects gamma rays that are not absorbed by the material 100B in the ground after being emitted from the radiation source, but are reflected and scattered. Cobalt-60, cesium-137, and other materials that emit gamma rays are used as standard materials for the radiation source 12B, and this radiation source is strictly sealed and stored in the storage section 12B' of the scattering-type RI densimeter. Similar to the scattering-type RI moisture meter 10A, in Figure 1, the dashed lines from the radiation source 12B and the radiation detector 14B represent the emitted or reflected radiation (gamma rays). The 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).

[0025] The radiation behavior simulator 20 is a radiation behavior measurement and analysis device (simulator) that simulates the scattering type RI instrument 10. Methods for measuring or analyzing (simulating) the behavior of neutrons and gamma rays include, for example, PHITS (code) manufactured by the Japan Atomic Energy Agency, but are not limited to this. PHITS is a Monte Carlo calculation code that simulates various radiation behaviors in all kinds of materials using nuclear reaction models and nuclear data. Since the configuration of the radiation behavior simulator 20 and the principle of PHITS are not essential to the present invention, a detailed explanation of them will be omitted.

[0026] The scanner 30 is capable of non-contact measurement (scanning) of the unevenness, i.e., the shape of irregularities, of the upper surface (plane) of the ground 100 in two or three dimensions. For example, a 3DLiDAR using a laser is used as the scanner 30, but a 2DLiDAR may also be used and is not limited to this. When taking measurements, the scanner 30 is positioned slightly above the ground 100 or on the plane of the ground. The scanner 30 outputs the vertical depth (amount of depression) X of the unevenness of the ground 100 as numerical data in real time for each angle around it. The amount of depression X refers to, for example, the length from the horizontal plane that contains the highest point of the unevenness, but is not limited to this. In Figure 1, the radiation behavior simulator 20, scanner 30, and scattering-type RI instrument 10 are arranged and described from top to bottom, but the arrangement is not limited to this. For example, when measuring the unevenness of the ground 100 with the scanner 30, it goes without saying that other components such as the scattering-type RI instrument 10 should be moved to an appropriate position, and the scanner can be placed in any position suitable for the measurement.

[0027] The control unit 40 is connected to the scattering-type RI instrument 10, the radiation behavior simulator 20, and the scanner 30. The dashed line in Figure 1 shows an example of the connection of the control device 40', which includes the control unit 40 and is described later, the scattering-type RI instrument 10, the radiation behavior simulator 20, and the scanner 30. Specifically, the control unit 40 is built into the control device 40', and the control device, including the control unit, is controlled by a CPU (processor) 40'-1 that has information processing capabilities. In addition to the control unit 40 that executes various programs, the control device 40' also includes a storage unit 42 that stores information using a storage medium such as flash memory, an input unit 44 that receives input from input means 44' such as a touch panel, keyboard, or buttons, and an output unit 46 that outputs to output (display) means 46' such as a display. The control device 40' may also have 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.

[0028] For example, the memory unit 42 stores the standard counting rate of radiation (neutrons and gamma rays), a function showing the correlation between the counting rate ratio and the amount of water or density, and a correction program (not shown) for the amount of water or density. It also stores numerical data measured by the scattering-type RI instrument 10, the radiation behavior simulator 20, the scanner 30, and numerical data of each correction value calculated by the control unit 40. The control unit 40 calculates the count rate ratio by dividing the count rate measured with the standard count rate stored in the memory unit 42, calculates the moisture content or density from the function and count rate ratio stored in the memory unit, and calculates and corrects the final correction value, which is the integrated correction value, from each correction value stored in the memory unit.

[0029] Figure 2 shows a schematic flowchart of a method for correcting moisture content or density according to one embodiment of the present invention, and Figure 3 shows a detailed flowchart of the method for correcting moisture content or density. The control unit 40 executes a moisture content or density correction program (not shown) stored in the memory unit 42, thereby sequentially performing the preparation steps S1-3, measurement steps S4 and S5, and correction step S6 shown in Figure 2. Preparation steps S1-3 are performed on the ground 100 in a level state, while measurement steps S4 and S5 are performed on the ground in a level state. Preparation steps S1-3 consist of a simulation preparation step S1, a full simulation step S2, and a correction value calculation step S3, while measurement steps S4 and S5 consist of a surface level measurement step S4 and an actual measurement step S5, respectively.

[0030] To perform these steps S1 to S6, the control unit 40 has preparation means 40-1 to 3 (simulation preparation steps S1 to correction value calculation step S3) which, in a method for correcting the moisture content or density of the ground 100 to be measured by the scattering type RI instrument 10, divides the ground to be measured into a plurality of grids at regular intervals in a state without unevenness, and sets one or more depression amounts representing the length in the direction perpendicular to the face of each grid, and uses the radiation behavior simulator 20 on the ground without unevenness to acquire each correction value for each combination of grid and depression amount; measurement means 40-4 (unevenness measurement step S4) which measures the shape of unevenness in the ground with unevenness using the scanner 30, corresponds the measured shape of unevenness to each grid, acquires the numerical value of the length in the direction perpendicular to the face of each grid as the depression amount, and calculates the average value of the depression amounts of each grid as the average depression amount; and correction means 40-6 (correction step S6) which acquires and corrects each correction value corresponding to the average depression amount of each grid, and functions as these means (Figures 2 and 3). More specifically, the simulation preparation means 40-1 (simulation preparation step S1) acquires a count rate related to moisture content or density using a radiation behavior simulator 20 that simulates a scattering-type RI instrument 10, with the ground 100 to be measured for moisture content or density in a level state; the entire simulation means 40-2 (entire simulation step S2) sets up multiple grids that divide the ground to be measured into regular intervals and one or more recess amounts representing the length perpendicular to the face of each grid, and acquires a count rate related to moisture content or density for all combinations of grids and recess amounts using the same radiation behavior simulator (as in simulation preparation step S1); and divides each count rate acquired (in the entire simulation step S2) by the count rate acquired (in simulation preparation step S1) to obtain the value obtained by dividing by the value obtained by dividing by the value obtained by the calculation The system includes a correction value calculation means 40-3 (correction value calculation step S3) which acquires each correction value for each combination of grid and depression amount, a unevenness measurement means 40-4 (unevenness measurement step S4) which measures the shape of unevenness in uneven ground with a scanner, corresponds the measured shape of unevenness to each grid, acquires the numerical value of the length perpendicular to the surface of each grid as the depression amount, and calculates the average value of the depression amounts of each grid as the average depression amount, and a correction means 40-6 (correction step S6) which acquires each correction value corresponding to the average depression amount of each grid (calculated in unevenness measurement step S4) from each correction value (calculated in correction value calculation step S3), takes the product of all the correction values ​​acquired for each grid as the cumulative correction value, and corrects the measured count rate ratio by dividing it by the cumulative correction value, and functions as these means (Figures 2 and 3). Note that the actual measurement step S5 is performed by the scattering type RI instrument 10 (10A, 10B).

[0031] The following mainly describes 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 method for correcting moisture content or density). 1. Explanation of each process The preparation process aims to obtain correction ratios related to moisture content or density by using a radiation behavior simulator 20 on a level ground 100. Specifically, this is carried out through a simulation preparation process S1, a full simulation process S2, and a correction value calculation process S3.

[0032] 1.1 Simulation preparation process S1 In the simulation preparation step S1 performed by the simulation preparation means 40-1, the ground 100 to be measured for moisture content or density is prepared without any unevenness, and the count rate related to moisture content or density is obtained using a radiation behavior simulator 20 that simulates a scattering-type RI instrument 10.

[0033] 1.2 Full Simulation Process S2 In the full simulation process S2, performed by the full simulation means 40-2, multiple grids are set to divide the ground to be measured into regular intervals, and one or more depression amounts representing the depth perpendicular to the face of each grid are set. The same radiation behavior simulator as in the simulation preparation process is used to obtain counting rates related to moisture content or density for all combinations of grids and depression amounts. Figure 4 shows a detailed flow chart of the entire simulation process for the moisture content or density correction method. Figure 5 shows a schematic diagram of an example of a ground grid in a scattering-type RI moisture meter, and Figure 6 shows a schematic diagram of an example of a ground grid in a scattering-type RI densimeter. The dashed line in Figure 5 shows a scattering-type RI moisture meter 10A, which includes a radiation source 12A and a radiation detector 14A, placed on the ground 100. The dashed line in Figure 6 shows a scattering-type RI densimeter 10B, which includes a radiation source 12B, a radiation detector 14B, and a shielding body 14B', placed on the ground 100.

[0034] First, the same ground 100 as in the simulation preparation step S1 is divided into multiple grids at regular intervals in a level state, and one or more depression amounts representing the depth X perpendicular to the face of each grid are set (S2-1). First, let's explain the grid. A grid is a grid created by dividing the surrounding ground, which is thought to be affected by the scattering type RI instrument (clearance), into multiple grid-like sections at regular intervals when the scattering type RI instrument 10 is placed on the upper surface (plane) of the ground 100 (Figures 5 and 6). The extent of the ground divided into grids is determined by considering the symmetry of radiation centered on the scattering type RI instrument and the influence of the RI instrument.

[0035] Specifically, Figures 5 and 6 divide the 30cm x 30cm area F (hereinafter referred to as "measurement area F") into sections. The grids closer to the radiation source 12 and radiation detector 14 are smaller, and the grids become larger as they move further away. This is because the effect of clearance becomes stronger the closer you are to the radiation source and radiation detector. In addition, to shorten the simulation time by the radiation behavior simulator 20, the grids further away from the radiation source 12 and radiation detector 14 are set to be larger. The numbers in the center of each grid in Figures 5 and 6 represent the grid numbers, starting from 1, from those closest to the radiation source line 12. Hereafter, each grid will be described as "No. n". In Figure 1, the scattering-type RI moisture meter 10A and the scattering-type RI densimeter 10B were shown as a single unit. However, for the sake of explanation, in the following sections, the scattering-type RI moisture meter 10A and the scattering-type RI densimeter 10B will be explained separately.

[0036] In a scattering-type RI moisture meter, for example, as shown in Figure 5, the ground 100 within a 30cm x 30cm measurement area F, indicated by the dashed line, is divided into 26 sections that are symmetrical both front-to-back and left-to-right. That is, as shown in Figure 5, there are grids numbered from No. 1 to 26. The dimensions (left-right x front-back) of the 26 grids in the scattering-type RI moisture meter 10A are, for example, 2cm x 2cm for grids No. 1-12, 3cm x 3cm for grids No. 13-22, 3cm x 4cm for grid No. 23, and 5cm x 5cm for grids No. 24-26, but the number and values ​​are not limited to these.

[0037] In a scattering-type radioisotope densimeter, for example, as shown in Figure 6, the ground 100 within a 30cm x 30cm measurement range F, indicated by the dashed line, is divided into 90 symmetrical sections. That is, as shown in Figure 6, there are grids numbered from No. 1 to 90. The dimensions (front-to-back × left-to-right) of the 90 grids in the scattering-type RI densimeter 10B are as follows: No. 1-60 are 1cm × 1cm, No. 61-71 and No. 75 are 2cm × 2cm, No. 72 and No. 76 are 2cm × 3cm, No. 74 and No. 78 are 3cm × 2cm, No. 73 and No. 77 are 3cm × 3cm, and No. 79-90 are 5cm × 5cm. However, the number and numerical values ​​are not limited to these figures.

[0038] Next, we will explain the amount of indentation. As shown in Figure 1, the amount of indentation is defined as the depth X in the direction perpendicular to the surface of each grid (i.e., the plane (upper surface) of the ground), and one or more amounts of indentation are set for each grid. The unit of the amount of indentation is, for example, millimeters (mm), but is not limited to this. Table 1 shows the combinations of grids and indentation amounts in a scattering-type RI moisture meter. In Table 1, 'a' is the number assigned sequentially from 1, and 'X' represents the indentation amount corresponding to 'a'. As can be seen in Table 1, multiple (a) indentation amounts X are set for each grid No. n. If we represent the grid and the number of elements for that grid as (n, a), then the indentation amount X is uniquely determined by the combination of (n, a). While it is possible to set one indentation amount X (one type, a=1) for each grid No. n, since the indentation amount X represents a virtual unevenness, setting multiple indentation amounts allows for accommodating various sizes and shapes of unevenness, as will be explained later.

[0039] [Table 1]

[0040] To elaborate further on the number a and the amount of indentation X, the number a and the amount of indentation X are set according to the distance between the radiation source (neutron source) 12A and the radiation detector 14A of the scattering-type RI moisture meter and the grid. For example, for grids No. 1 to 12, which are close to the radiation source 12A and the radiation detector 14A and are located in the left-right direction corresponding to the extension of the line connecting the radiation source and the radiation detector, Table 1 shows that 8 indentations (8 possibilities, a=8) of amount X are set. On the other hand, for grids No. 13 to 23 and No. 24 to 26, which are farther from the radiation source 12A and the radiation detector 14A, a smaller number a, of 5 to 4 (possibilities), is set, taking into account the effect of clearance.

[0041] Table 2 shows the combinations of grids and indentation amounts for the scattering-type RI densimeter. As shown in Table 2, in the scattering-type RI densimeter 10B as well, the number a and indentation amount X are set according to the distance between the scattering-type RI densimeter's radiation source (γ-ray source) 12B, radiation detector 14B and the grid. For example, for grids No. 1 to 60, which are close to the radiation source 12B and radiation detector 14B and located in the front-to-back direction corresponding to the extension of the line connecting the radiation source and radiation detector, 10 indentation amounts X (10 combinations, a=10) are set. For grids No. 61 to 78 and No. 79 to 90, which are farther from the radiation source 12B and radiation detector 14B, a smaller number a is set, such as 7 to 4 (combinations), taking into account the effect of clearance. In the scattering-type RI moisture meter 10A and the scattering-type RI densimeter 10B, it goes without saying that the number of grids n, the number of indentation settings a in each grid, and the indentation amount X are not limited to these values.

[0042] [Table 2]

[0043] Then, using the same radiation behavior simulator 20 as in the simulation preparation step S1, the count rates related to moisture content or density are obtained for all combinations of grid and depression amounts (Figure 4, S2-2 to S2-6). As shown in Figure 4, the initial values ​​n=1 and a=1 are set (S2-2). Then, referring to Table 1 for the scattering type RI moisture meter and Table 2 for the scattering type RI densimeter, the grid of No. n is indented by X mm for the combination of (n, a) (S2-3). For example, in the case of the scattering type RI moisture meter, the indentation amount X for the initial value (n, a)=(1,1) is 1 mm according to Table 1, so grid No. 1 is artificially indented by 1 mm. Next, with the grid of No. n indented by X mm, the behavior of radiation is simulated using the same radiation behavior simulator 20 as in the simulation preparation step S1, and the acquired count rate is stored in the control unit 40 (storage unit 42) (S2-4).

[0044] If the following a exists, n remains unchanged and 1 is added to a (S2-5). If the following a does not exist, proceed to the next S2-6. For example, in a scattering type RI moisture meter, if the initial value is (n, a) = (1, 1), the following a (a=2) exists in Table 1, so set (n, a) = (1, 2) and return to S2-3. The amount of depression X at (n, a) = (1, 2) is from Table 1. 3 Since it is mm, grid No. 1 is artificially 3 The model is indented by mm (S2-3), then simulated and saved (S2-4).

[0045] Repeating steps S2-3 to S5 completes all simulations at grid No. n. That is, if the next a does not exist (S2-5), 1 is added to n and a is reset to its initial value of 1 (S2-6), and the process returns to S2-3. For example, in a scattering type RI moisture meter, the initial values ​​(n, a) = (1, 8 In the case of ), the following a(a= 9 ) does not exist in Table 1. Therefore, we add 1 to n and return a to its initial value of 1, so that (n, a) = (2, 1) and return to S2-3. The amount of indentation X at (n, a) = (2, 1) is again 1 mm from Table 1, so we artificially indent grid No. 2 by 1 mm (S2-3), simulate and save (S2-4). Thus, in the case of a scattering-type RI moisture meter, an artificial amount of depression is set as a virtual unevenness for all grids listed in Table 1, and the count rate related to moisture content is simulated and stored for these combinations (S2-2 to S2-6). Similarly, for density, the count rate related to density is simulated and stored for all combinations listed in Table 2.

[0046] 1.3 Correction value calculation process S3 In the correction value calculation step S3 performed by the correction value calculation means 40-3, each count rate obtained in the entire simulation step S2 is divided by the count rate obtained in the simulation preparation step S1, and the resulting values ​​are obtained as each correction value t for each combination of grid and recess amount. Let each obtained correction value be t. Each obtained correction value t is stored in the control unit 40 (storage unit 42) for each combination of grid and recess amount.

[0047] 1.4 Unevenness measurement process S4 In the unevenness measurement process S4, which is performed by the unevenness measurement means 40-4, the scanner 30 measures the shape of the unevenness of the uneven ground 100, the measured shape of the unevenness is associated with each grid, the numerical value of the length perpendicular to the surface of each grid is obtained as the amount of depression, and the average value of the depression amounts of each grid is calculated as the average amount of depression. In the unevenness measurement process S4, the uneven ground 100 that is actually to be measured is measured. First, the scanner 30 non-contactively measures (scans) the shape of the unevenness of the uneven ground 100 in two or three dimensions. The measurement result includes the vertical depth (amount of depression) X of the unevenness of the ground as numerical data and is stored in the control unit 40 (storage unit 42). For example, if a 3DLiDAR is used as the scanner 30, the vertical depth (amount of depression) X of the unevenness of the ground 100 is output as numerical data in real time for each angle around it. Figure 7 shows a schematic diagram illustrating an example of the scanner's measurement results. The scanner 30 displays the shape of the unevenness as shown in Figure 7, with darker colors indicating greater unevenness, i.e., a larger (deeper) depth X.

[0048] Next, the control unit 40 associates the shape of the unevenness (including the depression amount X, which is numerical data) measured by the scanner 30 with multiple grids set in the simulation preparation step S1, and acquires it as the depression amount relative to the surface of each grid. Specifically, each grid consists of a small area such as 1 cm square or 5 cm square, but if we assume that the actual ground to be measured is divided into grids, the inside of the grid is not necessarily flat due to the soil type, etc., and multiple small uneven areas occur. In other words, if we assume that the actual ground to be measured is divided into grids, the depression amount in each grid is not constant (uniform). Therefore, in order to average (uniformize) within each grid, the control unit 40 calculates the average value of the depression amount measured by the scanner 30 in each grid. This average value of the depression amount in each grid is called the "average depression amount". The control unit 40 calculates the average depression amount for each grid and saves the average depression amount for each grid.

[0049] Figure 8 shows a schematic diagram illustrating an example of the average depression amount in each grid. Referring to Figures 7 and 8 for the scattering-type RI densimeter, Figure 7 directly shows the unevenness of ground 100 regardless of the grid, while Figure 8 corresponds Figure 7 to a grid, calculates the average depression amount in each grid, and colors each grid according to the average depression amount. Similar to Figure 7, in Figure 8, the darker the color, the greater the unevenness (depth; in this case, the average depression amount).

[0050] 1.5 Measurement Process S5 In the measurement process S5, which is performed using the scattering-type RI instrument 10 (10A, 10B), the measured count rate ratio related to moisture content or density is obtained for the uneven ground 100 measured in the unevenness measurement process S4 using the scattering-type RI instrument. For explanatory purposes, the term "measured count rate ratio" refers to the actual count rate ratio (numerical data) of the uneven ground 100 that is the target of measurement using the scattering-type RI instrument 10 (10A, 10B). The measured count rate ratio is stored in the control unit 40 (storage unit 42).

[0051] 1.6 Correction process S6 In the correction process S6 performed by the correction means 40-6, each correction value corresponding to the average indentation amount of each grid calculated in the unevenness measurement process S4 is obtained from each correction value t calculated in the correction value calculation process S3, and the product of all the correction values ​​t obtained for each grid is taken as the cumulative correction value T, and the measured count rate ratio obtained in the actual measurement process S5 is corrected by dividing it by the cumulative correction value T. In other words, the cumulative correction value T becomes the final correction value for correcting the measured count rate ratio. First, the cumulative correction value T is calculated using the following equation 1. In the equation, t is each correction value calculated in the correction value calculation process S3, n is the total number of grids, and a is the number assigned sequentially from 1 as described above.

number

[0052] Based on the above, the corrected count rate ratio R' is calculated using Equation 2. In the formula, R is the count rate ratio before correction, i.e., the measured count rate ratio measured in the actual measurement process S5.

number

[0053] 2. First verification (using a simulator) Using the moisture content or density correction system 1 (which embodies the moisture content or density correction method described above), two verifications (specific examples) were performed. These are described below. In the first verification, ground with known moisture content and density was used, and the effect was confirmed by using the radiation behavior simulator 20 instead of the scattering type RI instrument 10 in the measurement process S5. In the second verification, the scattering type RI instrument 10 was used in the measurement process 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.

[0054] In the first verification, although the soil has known moisture content and density (moisture content 0.336 g / cm³), 3 , density 1.750g / cm 3), simulation preparation step S1 was performed using the radiation behavior simulator 20. In the entire simulation process S2, the 30cm x 30cm measurement area F of the ground 100 in a generally level state was divided into 26 grids for the scattering-type RI moisture meter 10A and 90 grids for the scattering-type RI density meter 10B (S2-1, Figures 5 and 6). Then, combinations of grids and depression amounts X were set as shown in Tables 1 and 2 (S2-1), and the count rate related to moisture content or density was obtained for all grid and depression amount combinations shown in Tables 1 and 2 (S2-2 to S2-6). In the correction value calculation step S3, each counting rate obtained in the entire simulation step S2 was divided by the counting rate obtained in the simulation preparation step S1, and the resulting values ​​were used to obtain each correction value t for each combination of grid and recess amount.

[0055] In the unevenness measurement process S4, multiple patterns of unevenness were artificially set and created on the ground 100. For example, for the reasons shown in Tables 3 and 4, five patterns of unevenness 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 for patterns 4 and 5 of the scattering-type RI moisture meter in Table 3, and patterns 3 to 5 of the scattering-type RI densimeter in Table 4 were set to maximize the change in the counting rate ratio (i.e., each correction value t). [Table 3] [Table 4]

[0056] The verification of Pattern 1 of the scattering-type RI moisture meter 10A shown in Table 3 will be described in detail below. In Pattern 1 of the scattering-type RI moisture meter 10A, the indentation amount of all 26 grids is set to 5 mm. The scanner 30 measures the shape of the unevenness (in this case, Pattern 1), and the control unit 40 calculates the average indentation amount of each grid corresponding to each grid (S4).

[0057] In the measurement process S5, a radiation behavior simulator was used before verification with the actual equipment (second verification). For the uneven ground 100 measured in the unevenness measurement process S4, in this case, the measured count rate ratio related to moisture content was obtained for pattern 1 of the scattering-type RI moisture meter 10A shown in Table 3 (S5). Then, each correction value t corresponding to the average depression amount of each grid was obtained, and the product of all the obtained correction values ​​t was taken as the cumulative correction value T (the final correction value) (see correction process S6, equations 1 and 2).

[0058] The same process (unevenness measurement process S4 to correction process S6) was performed for all patterns 2 to 5 of the scattering-type RI moisture meter in Table 3 and all patterns 1 to 5 of the scattering-type RI densimeter 10B in Table 4. The results of the first verification are shown in Tables 5 and 6 below. In Tables 5 and 6, "Counting Rate Ratio" represents the measured counting rate ratio obtained in the measurement process S5, and "Accumulated Correction Value" represents the accumulated correction value T calculated in the correction process S6. As shown in Tables 5 and 6, both the scattering-type RI moisture meter and the scattering-type RI densimeter show no significant error between the measured count rate ratio and the integrated correction value T, indicating that correction values ​​close to the actual (measured) values ​​are calculated. [Table 5] [Table 6]

[0059] 3. Second verification (using actual equipment) A second verification was conducted to confirm the validity of the first verification. In the second verification, a soil tank experiment was performed using the scattering-type RI instrument 10 (actual unit). This explanation will focus on the differences from the first verification. Note that due to the use of the actual unit, the order of some steps is different. In the second verification, a soil tank was created by filling a metal mold measuring 60cm front-to-back x 60cm left-to-right x 40cm top-to-bottom (vertical direction, depth) with mountain sand in four layers. Similar to the first verification, the 30cm x 30cm measurement area F of the soil tank's ground 100 was divided into 26 grids for the scattering-type RI moisture meter 10A and 90 grids for the scattering-type RI densimeter 10B.

[0060] First, measurements were taken for 5 minutes using a scattering-type RI densimeter 10A and a scattering-type RI moisture meter 10B on the ground 100 of the soil tank, which was free of unevenness (simulation preparation step S1). Next, artificial unevenness was created by indenting the upper surface of the ground 100 of the soil tank according to patterns 1 to 3 in Tables 3 and 4, and the count rate ratio was calculated (entire simulation process S2, correction value calculation process S3). Then, the shape of the uneven surface was measured with a 3DLiDAR (scanner) 30 (unevenness measurement process S4, see Figure 7), and measurements were taken for 5 minutes using the scattering-type RI densimeter 10A and the scattering-type RI moisture meter 10B to obtain the measured count rate ratio (measurement process S5).

[0061] Next, the unevenness shape measured by the 3DLiDAR (scanner) 30 was mapped to each grid, and the average indentation amount for each grid was calculated (unevenness measurement process S4, see Figure 8). Then, each correction value t corresponding to the average indentation amount for each grid was obtained, and the cumulative correction value T was calculated (correction process S6, see Equations 1 and 2).

[0062] The results of the second verification are shown in Tables 7 and 8 below. In Tables 7 and 8, "Correction Value" represents the actual count rate ratio obtained in the measurement process S5, and "PHITS Cumulative Correction Value" represents the cumulative correction value T calculated in the correction process S6. For the scattering-type RI densimeters in Table 8, one pattern was observed where the cumulative correction value T was larger than the measured count rate ratio, i.e., an overestimation (Pattern 3). However, it can be seen that correction values ​​that were generally accurate were calculated. For the scattering-type RI moisture meters in Table 7, there was no large error between the measured count rate ratio and the cumulative correction value T, indicating that correction values ​​close to the actual (measured) values ​​were calculated. [Table 7] [Table 8]

[0063] According to the moisture content or density correction system 1 (which embodies a method for correcting moisture content or density), measurement feasibility is not determined by whether the value is above or below a threshold. Instead, an artificial, virtual unevenness is set for each grid, and each correction value t is determined by the average unevenness. Since each correction value t represents the magnitude of the influence (increase / decrease ratio) that the grid and the amount of unevenness have on the count rate ratio, the cumulative correction value T, which is the final correction value, is calculated by accumulating all the correction values ​​t obtained for each grid. In other words, by accumulating all the individual correction values ​​t, it becomes possible to perform a surface-level correction that takes into account the effects of unevenness in all grids. Therefore, even in ground with significant unevenness, correction values ​​close to actual measurements can be calculated, allowing for more accurate measurement and correction of moisture content and density. Since the grid represents the location of virtual unevenness and the depression amount X represents the depth of virtual unevenness, by setting a finer grid and depression amount in the entire simulation process S2, it is possible to correct the values ​​to be close to the actual moisture content and density, regardless of the soil type and shape of unevenness of the ground being measured.

[0064] The embodiments described above are for illustrative purposes only and do not limit the invention in any way. It goes without saying that any modifications, alterations, or other changes made within the technical scope of this invention are also included within this invention.

[0065] For example, as in the second verification, the measurement process performed on uneven ground may be carried out before the preparation process performed on uneven ground. Furthermore, as mentioned above, the amount of moisture in the ground can be expressed not only as a water content ratio, but also as water content, water content percentage, etc. In the unevenness measurement process, machine learning and AI may be used in the process of corresponding the shape of the measured unevenness to each grid and in the calculation of correction values. Moreover, as mentioned above, the radiation behavior simulator and scanner are not limited to 3DLiDAR and PHITS, respectively. [Industrial applicability]

[0066] This invention can be applied to methods and systems for correcting the moisture content or density of soil. [Explanation of Symbols]

[0067] 1. Moisture content or density correction system 10 Scattering type RI instrument 10A scattering type RI moisture meter 10B Scattering type RI density meter 20 Radiation Behavior Simulator 30 Scanners 40 Control Unit 40-1 Simulation preparation means 40-2 All Simulation Methods 40-3 Correction Value Calculation Method 40-4 Unevenness measurement means 40-6 Correction means S1-3 Preparation process (S1 Simulation preparation process, S2 Full simulation process, S3 Correction value calculation process) S4, 5 measurement process (S4 unevenness measurement process, S5 actual measurement process) S6 correction process

Claims

1. In a method for correcting the moisture content or density of the ground to be measured by a scattering-type radioisotope instrument, The method for correcting moisture content or density comprises a preparation step, a measurement step, and a correction step. The preparation process includes a simulation preparation process, a full simulation process, and a correction value calculation process, while the measurement process includes a leveling measurement process and an actual measurement process. The simulation preparation process involves obtaining the count rate related to the moisture content or density using a radiation behavior simulator that simulates a scattering-type RI instrument, while ensuring the ground to be measured for moisture content or density is level. The entire simulation process involves setting up multiple grids that divide the ground to be measured into regular intervals, and one or more depression amounts representing the length perpendicular to the face of each grid. Using the same radiation behavior simulator as in the simulation preparation process, the counting rate related to moisture content or density is obtained for all combinations of grids and depression amounts. The correction value calculation process involves dividing each count rate obtained in all simulation processes by the count rate obtained in the simulation preparation process, and obtaining the resulting values ​​as the respective correction values ​​for each combination of grid and recess amount. The unevenness measurement process involves using a scanner to measure the shape of unevenness in the ground, assigning the measured shape of unevenness to each grid, obtaining the length perpendicular to the surface of each grid as the amount of depression, and calculating the average value of the depression amounts for each grid as the average depression amount. The measurement process involves obtaining the count rate ratio of the measured moisture content or density using a scattering-type radioisotope instrument in the uneven ground measured in the unevenness measurement process. The correction process involves obtaining each correction value corresponding to the average indentation amount of each grid calculated in the unevenness measurement process from each correction value calculated in the correction value calculation process, taking the product of all the correction values ​​obtained for each grid as the cumulative correction value, and correcting by dividing the measured count rate ratio obtained in the actual measurement process by the cumulative correction value. A method for correcting moisture content or density, characterized by the following features.

2. The method for correcting moisture content or density according to claim 1, wherein the scattering type RI instrument comprises either a scattering type RI moisture meter or a scattering type RI densimeter, or comprises only one of them.

3. A scattering-type radioisotope instrument that uses radiation to measure the moisture content or density of the ground, A radiation behavior simulator that simulates a scattering-type radioisotope instrument, A scanner that measures the shape of uneven ground, A scattering-type radioisotope instrument, a radiation behavior simulator, and a scanner are connected, along with a control unit that corrects for the moisture content or density of the ground. A moisture content or density correction system comprising at least the following: The control unit is The soil to be measured for moisture content or density is prepared in a level state, and the count rate related to moisture content or density is obtained using a radiation behavior simulator that simulates a scattering-type RI instrument. Multiple grids are defined to divide the ground to be measured into regular intervals, and one or more depression amounts are defined to represent the length perpendicular to the surface of each grid. A radiation behavior simulator is then used to obtain counting rates related to moisture content or density for all combinations of grids and depression amounts. The count rate for all grid and recess amount combinations is divided by the count rate obtained from the radiation behavior simulator, and the resulting values ​​are obtained as the respective correction values ​​for each grid and recess amount combination. The shape of uneven ground is measured using a two-dimensional or three-dimensional scanner, the measured shape of unevenness is associated with each grid, the length perpendicular to the surface of each grid is obtained as the amount of depression, and the average value of the depression amounts for each grid is calculated as the average depression amount. In uneven ground, the count rate ratio of actual measurements related to moisture content or density is obtained using a scattering-type radioisotope instrument. A moisture content or density correction system that obtains correction values ​​corresponding to the average amount of depression for each grid from the correction values ​​for each combination of grid and depression amount, takes the product of all the correction values ​​obtained for each grid as the cumulative correction value, and corrects the measured count rate ratio by dividing it by the cumulative correction value.

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