Method and program for exploring underground buried pipe

Abstract

To provide a method and a program for exploring an underground buried pipe capable of detecting the underground buried pipe with high accuracy.SOLUTION: A method for exploring an underground buried pipe includes: a reflected wave acquisition step of acquiring reflected waves of radio waves of an underground radar transmitted toward a ground at a plurality of measurement points by scanning the underground radar along a survey line; an underground buried pipe detection step of detecting the reflected waves from the underground buried pipe appearing in a hyperbolic shape from an image created by arranging waveforms of the reflected waves for each scanning distance of the underground radar; and a reflection coefficient sign estimation step of estimating a sign of a reflection coefficient of the underground buried pipe.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a method and program for detecting underground buried pipes. [Background technology]

[0002] There are known methods for estimating the location of underground pipes. For example, Non-Patent Document 1 summarizes a method for classifying reflectors such as buried pipes based on the instantaneous phase of the reflected waves, in which a ground-penetrating radar transmits radio waves toward the ground and acquires the reflected waves from the ground. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Byeongjin Park et al., Underground Object Classification for Urban Roads Using Instantaneous Phase Analysis of Ground-Penetrating Radar (GPR) Data, Remote Sensing, 2018, 10, 1417 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the technology of Non-Patent Document 1, it is difficult to improve the accuracy of detecting underground pipes.

[0005] In view of the above, an object of the present disclosure is to provide an underground pipe exploration method and program that can detect underground pipes with high accuracy. [Means for solving the problem]

[0006] A method for exploring an underground pipe according to a first aspect of the present disclosure includes: (1) a reflected wave acquiring step of scanning the ground with the underground radar along a measurement line to acquire reflected waves of radio waves transmitted from the underground radar toward the ground at a plurality of measurement points; an underground pipe detection step of detecting reflected waves from underground pipes that appear in a hyperbolic shape from an image created by arranging the waveforms of the reflected waves for each scanning distance of the underground radar; a reflection coefficient sign estimation step of estimating the sign of the reflection coefficient of the underground buried pipe; Includes:

[0007] A method for detecting an underground pipe according to one embodiment of the present disclosure includes: (2) an instantaneous phase calculation step of calculating an instantaneous phase of the reflected wave; a cosine calculation step of calculating the cosine of the instantaneous phase; Further comprising: In the reflection coefficient sign estimating step, a sign of the reflection coefficient of the underground pipe is estimated based on a change in the sign of the cosine in the time direction. The method for detecting underground pipes described in (1) above.

[0008] A method for detecting an underground pipe according to one embodiment of the present disclosure includes: (3) In the cosine calculation step, an average of cosines of instantaneous phases along each hyperbolic shape is calculated for a plurality of hyperbolic reflected waves adjacent in the time direction; The method for exploring an underground pipe according to (2) above, wherein in the reflection coefficient sign estimating step, a change in the sign of the cosine in the time direction is determined based on an average of the cosine.

[0009] A method for detecting an underground pipe according to one embodiment of the present disclosure includes: (4) In the underground pipe detection step, a plurality of images are obtained in a direction intersecting with the measurement line by arranging the waveforms of the reflected waves for each scanning distance of the underground radar, and when a hyperbolic reflected wave having vertices whose measurement points are located on a straight line is detected from the plurality of obtained images, the underground object corresponding to the hyperbolic reflected wave is determined to be the underground pipe. The method for exploring an underground pipe is described in any one of (1) to (3) above.

[0010] A method for detecting an underground pipe according to one embodiment of the present disclosure includes: (5) The method further includes a depth estimation step of extracting reflected waves from underground pipes that appear in a hyperbolic shape from the image created by arranging the waveforms of the reflected waves for each scanning distance of the underground radar, estimating the propagation speed of the radio waves in the ground based on the shape of the hyperbolic reflected waves, and estimating the depth at which the underground pipes are installed. The method for exploring an underground pipe is described in any one of (1) to (4) above.

[0011] A method for detecting an underground pipe according to one embodiment of the present disclosure includes: (6) In the underground pipe detection step, a hyperbola corresponding to the underground pipe is detected from an image created by arranging the absolute values ​​of the cosine of the instantaneous phase of the reflected wave for each scanning distance of the underground radar. This is a method for detecting underground pipes according to any one of (1) to (5) above.

[0012] A program according to a second aspect of the present disclosure includes: (7) On the computer, a reflected wave acquiring step of acquiring reflected waves of radio waves transmitted from the underground radar toward the ground at a plurality of measurement points by scanning the underground radar; an underground pipe detection step of detecting reflected waves from underground pipes that appear in a hyperbolic shape from an image created by arranging the waveforms of the reflected waves for each scanning distance of the underground radar; a reflection coefficient sign estimation step of estimating the sign of the reflection coefficient of the underground buried pipe; It is a program to execute the above. [Effects of the Invention]

[0013] According to the present disclosure, underground pipes can be detected with high accuracy. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a block diagram showing a schematic configuration of an exploration system that implements a method for exploring underground buried pipes according to an embodiment of the present invention. [Figure 2] 1 is a flowchart illustrating a computer-implemented method for detecting underground pipes. [Figure 3] This is an image in which the waveforms of reflected waves are arranged according to the scanning distance (distance) of the ground-penetrating radar. [Figure 4] The image shown in Figure 3 is created by coloring the image based on the magnitude of the reflected wave. [Figure 5] FIG. 10 is a diagram showing how multiple images created by arranging the waveforms of reflected waves for each scanning distance of the underground radar are acquired in a direction intersecting the measurement line. [Figure 6] This figure shows reflected waves from underground pipes that appear in various hyperbolic shapes when the propagation speed of radio waves is changed in an image created by arranging the waveforms of reflected waves for each scanning distance of the underground radar. [Figure 7] The image shown in Figure 3 is created by coloring the image based on the magnitude of the reflected wave. [Figure 8] FIG. 4 shows the instantaneous phase of the reflected wave at a distance of 7.9 m. [Figure 9] FIG. 9 is a diagram showing the instantaneous phases of the multiple reflected waves shown in FIG. [Figure 10] FIG. 5 is a diagram showing the cosine of the instantaneous phase of the multiple reflected waves shown in FIG. 4. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following drawings, the same components are designated by the same reference numerals.

[0016] 1, an investigation system 100 for implementing an underground pipe investigation method according to an embodiment of the present invention will be described. The investigation system 100 includes a mobile unit 10, a ground penetrating radar 20, and a computer 30.

[0017] An underground pipe is a pipe through which gas, water, sewage, electrical wires, etc. run. The pipe is buried, for example, under a road. The diameter of the pipe is approximately 10 mm to 500 mm. The diameter of the pipe may vary along its axial direction. The depth of the pipe is, for example, less than 2 m, but is not particularly limited. The pipe may be curved. Whether the pipe exists may be unknown before the exploration system 100 performs exploration. The approximate location of the pipe may be known from a road register, etc.

[0018] The moving unit 10 moves the exploration system 100 on the ground to be explored. The moving unit 10 may include wheels. The moving unit 10 may further include a drive unit for the wheels. The drive unit may be a motor. As another example, an operator may drive the wheels. The moving unit 10 may measure and store the distance and direction of movement.

[0019] The underground radar 20 transmits radio waves toward the ground and receives reflected waves of the radio waves. While the exploration system 100 is moving, the underground radar 20 may periodically transmit radio waves. The underground radar 20 may measure the time difference between the time when the radio waves are transmitted and the time when they are received. The underground radar 20 may be integrated with the mobile unit 10.

[0020] The underground radar 20 may be card-shaped. The distance that the underground radar can search is, for example, about 0.5 m to 2.5 m. The center frequency of the radio waves transmitted by the underground radar is designed appropriately. Generally, when the center frequency of the radio waves is high, the resolution improves but the search depth becomes shallow. Conversely, when the center frequency of the radio waves is low, the resolution decreases but the search depth becomes deep. The center frequency of the radio waves may be selected from the range of 200 MHz to 900 MHz.

[0021] The computer 30 controls the overall operation of the exploration system 100. The computer 30 includes one or more processors. The computer 30 may be able to communicate with the mobile unit 10 and the ground penetrating radar 20. The computer 30 may receive data from the mobile unit 10 and the ground penetrating radar 20 via a medium. The computer 30 may be located remotely from the mobile unit 10 and the ground penetrating radar 20.

[0022] Next, a description will be given of the software configuration of the computer 30. A program used to control the operation of the computer 30 is stored in the storage unit. When the program is read by the control unit, it causes the control unit to execute the method for exploring underground buried pipes.

[0023] An example of the operation of the exploration system 100 will be described with reference to Fig. 2. The operation described below corresponds to the underground pipe exploration method according to this embodiment. That is, the pipeline exploration method according to the present disclosure includes, for example, steps S1 to S3 shown in Fig. 2.

[0024] In S1 of FIG. 2, the exploration system 100 causes the underground radar 20 to scan along a measurement line. At this time, the mobile unit 10 moves the exploration system 100 on the ground. The movement direction may be a direction that is considered to be perpendicular to the underground buried pipe. The underground radar 20 transmits radio waves toward the ground at multiple measurement points. In the example shown here, the underground radar 20 continuously transmits three waves: a pulse wave with a positive sign, a pulse wave with a negative sign, and a pulse wave with a positive sign. For example, every time the mobile unit 10 moves 1 cm, the underground radar 20 continuously transmits the three waves. The underground radar 20 receives reflected waves of the radio waves. The measurement line is, for example, a zigzag shape.

[0025] In S2 of Fig. 2, the computer 30 of the exploration system 100 receives reflected waves of radio waves received by the underground radar 20. The computer 30 creates an image in which the waveforms of the reflected waves are arranged for each scanning distance of the underground radar 20 (the distance of the exploration system 100) as shown in Fig. 3. In the image shown in Fig. 3, the waves shown in bold indicate reflected waves received at a distance of 1.4 m. In the image, the waves located further to the right indicate reflected waves received when the underground radar 20 of the exploration system 100 has traveled a greater distance.

[0026] The computer 30 further colors the image shown in FIG. 3 based on the magnitude and sign of the reflected waves, creating the image shown in FIG. 4. In the image, reflected waves from underground pipes may appear as hyperbolic curves HA1, HA2, and HA3 (umbrella-shaped). These hyperbolic reflected waves indicate the presence of underground pipes. This phenomenon occurs because the peak time of the reflected waves is shortest when the search position is directly above the buried pipe, and the peak of the reflected waves arrives gradually later as the search position moves away from the buried pipe. The computer 30 may also perform background removal processing on the image. Hereinafter, the hyperbolic curves HA1, HA2, and HA3 are collectively referred to as the group of hyperbolic curves HA.

[0027] When the phase of the transmitted wave and the phase of the reflected wave are the same, i.e., when the signs of the reflected wave are positive, negative, and positive in time order for the transmitted pulses that are positive, negative, and positive in time order, the reflection coefficient is positive. On the other hand, when the phase of the transmitted wave is the opposite phase of the reflected wave, i.e., when the signs of the reflected wave are negative, positive, and negative in time order, the reflection coefficient is negative. The reflection coefficient is determined by the difference in the dielectric constants of the buried object and the ground. When the dielectric constant of the buried object is lower than that of the ground, the reflection coefficient is positive, and when the dielectric constant of the buried object is higher, the reflection coefficient is negative. When an underground pipe is present, the reflection coefficient is positive if the underground pipe is made of a rigid polyvinyl chloride pipe, polyethylene pipe, or the like, and contains air inside. On the other hand, when the underground pipe is made of a steel pipe, Hume pipe, or the like, the reflection coefficient is negative. Therefore, the material of the underground object can be identified by the sign of the reflection coefficient. The user of the underground buried object may be identified from the valves, manhole covers, etc. on the ground surface. By adding this information, the type of underground buried pipe may be identified.

[0028] If the underground pipe is a gas pipe and the pressure inside the pipe is high, the underground pipe is often a steel pipe. On the other hand, if the pressure inside the pipe is low, the underground pipe is often a polyethylene pipe. If the underground pipe is a sewer pipe or a storm water pipe, the underground pipe may be a rigid polyvinyl chloride pipe or a Hume pipe. If the underground pipe is a water supply pipe, the underground pipe may be a steel pipe or a rigid polyvinyl chloride pipe.

[0029] The computer 30 detects reflected waves from underground pipes that appear in the shape of hyperbolae HA1, HA2, and HA3 from the images shown in FIG. 4 or FIG. 3. In the example shown here, the signs of the reflected waves that appear in the shape of hyperbolae HA1, HA2, and HA3 are negative, positive, and negative in time order, so it is estimated that the buried pipes have a negative reflection coefficient. The computer 30 also identifies the location of the underground pipes by detecting the reflected waves that appear in the shape of hyperbolae. The detection of reflected waves may be performed by semblance analysis, pattern matching, or the like. In semblance analysis, a search is performed by shifting the time and distance while calculating the semblance. The semblance value is between 0 and 1, and for reflected waves that appear in the shape of hyperbolae, the semblance approaches 1. In other words, when the semblance is high, a hyperbolic reflected wave is present.

[0030] As shown in FIG. 5, the computer 30 may acquire multiple images created by arranging the waveforms of the reflected waves for each scanning distance of the underground radar 20 in a direction (direction d2) intersecting the survey line (along direction d1). Specifically, in S1 of FIG. 2, the exploration system 100 causes the underground radar 20 to scan along a zigzag survey line. More specifically, the mobile unit 10 moves the exploration system 100 in a first direction d1 on the ground to acquire a first image F1 created by arranging the waveforms of the reflected waves for each scanning distance of the underground radar 20. Next, the mobile unit 10 moves the exploration system 100 in a second direction d2 intersecting with the first direction. Thereafter, the mobile unit 10 moves the exploration system 100 on the ground in a direction opposite to the first direction d1 to acquire a second image F2 created by arranging the waveforms of the reflected waves for each scanning distance of the underground radar 20. By repeating the operations described above, three or more images created by arranging the waveforms of the reflected waves for each scanning distance of the underground radar 20 may be acquired.

[0031] When reflected waves of the shape of hyperbola HA, HA', with the measurement points of vertices t1, t2 located on a straight line, are detected from the acquired images F1, F2, the computer 30 may determine that the underground buried object 1000 corresponding to the reflected waves of the shape of hyperbola HA, HA' is an underground pipe. The computer 30 may detect a three-dimensional hyperbolic wavefront. Therefore, the computer 50 can distinguish between underground pipes and underground buried objects other than underground pipes. Furthermore, even if no underground pipes are present in the ground, if there is a difference in dielectric constant, hyperbolic reflected waves may appear in the image. As described above, the computer 50 can distinguish between reflected waves from underground pipes and reflected waves from when no underground pipes are present. Therefore, the computer 50 can detect underground pipes with higher accuracy.

[0032] The computer 30 may estimate the propagation speed of the radio wave in the ground based on the shape of the extracted hyperbolic reflected wave. Figure 6 is a diagram showing the reflected wave that appears in a hyperbolic shape from an underground buried pipe when the propagation speed of the radio wave is changed. The curvature of the hyperbola changes as the propagation speed of the radio wave changes. Therefore, the computer 30 can estimate the propagation speed of the radio wave based on the curvature of the extracted hyperbolic reflected wave.

[0033] As described above, the underground radar 20 may measure the time difference between the time when the radio wave is transmitted and the time when the radio wave is received. The computer 30 may estimate the depth at which the underground pipe is installed based on the time difference and the estimated propagation speed of the radio wave.

[0034] When the reflection coefficient is negative, the group of hyperbolas HA consists of an upper negative hyperbola HA1, a middle positive hyperbola HA2, and a lower negative hyperbola HA3, as shown in Figure 4. In the negative hyperbola, the sign of the magnitude of the reflected wave is negative, and in the positive hyperbola, the sign of the magnitude of the reflected wave is positive.

[0035] Figure 7 is an image created by coloring the reflected waves based on the magnitude and sign, focusing on underground pipes with positive reflection coefficients. In this image, the reflected waves from the underground pipes appear as hyperbolas HB1, HB2, and HB3. The upper hyperbola HB1 and the lower hyperbola HB3 are positive hyperbolas. The central hyperbola HB2 is negative hyperbola.

[0036] As explained above, the order of sign changes of the reflected wave amplitude in each hyperbola of the group of hyperbolae that constitute the detected reflected wave differs depending on the sign of the reflection coefficient.

[0037] 2, the computer 30 estimates the sign of the reflection coefficient of the underground pipe based on the order. The computer 30 may estimate the sign of the reflection coefficient of the underground pipe by taking into consideration the waveform of the transmitted radio wave.

[0038] The computer 30 of the surveying system 100 may calculate the instantaneous phase of the reflected wave. The computer 30 may calculate the instantaneous phase of the reflected wave using a Hilbert transform. The Hilbert transform shifts the instantaneous phase of the wave by 90°. When a wave whose waveform is represented by cosωt is subjected to the Hilbert transform, the waveform of the transformed wave is represented by sinωt. The argument of the complex number represented by the real and imaginary parts of the reflected wave is the phase (see M.T. Taner, F. Koehler, and R.E. Sheriff, (1979), "Complex seismic trace analysis," GEOPHYSICS 44: 1041-1063). Figure 8 shows the instantaneous phase of the reflected wave (along line L in Figure 4) at a distance of 7.9 m in Figure 4. Referring to Figure 4, times T1, T2, and T3 are the times when hyperbolas HA1, HA2, and HA3 exist at a distance of 7.9 m, respectively. Figure 8 also shows times T1, T2, and T3. As shown in Figure 8, the instantaneous phase of the negative hyperbola HA1 is approximately π, the instantaneous phase of the positive hyperbola H2 is approximately 0, and the instantaneous phase of the negative hyperbola HA3 is approximately -π. Figure 9 shows the instantaneous phases of the numerous reflected waves shown in Figure 4. The instantaneous phase does not depend on the magnitude of the reflected wave amplitude. In other words, it is not affected by the contrast of the images created by arranging the images according to the scanning distance of the ground-penetrating radar. Therefore, when people or AI look at images and make judgments, they may miss something depending on the degree of contrast, but judgments based on the instantaneous phase reduce this.

[0039] The computer 30 of the exploration system 100 may calculate the cosine of the instantaneous phase θ. As an example of a case where the reflection coefficient is negative, FIG. 10 shows the cosine of the instantaneous phase θ of the multiple reflected waves shown in FIG. 4. The cosine of the negative hyperbola HA1 is approximately -1, the cosine of the positive hyperbola HA2 is approximately 1, and the cosine of the negative hyperbola HA3 is approximately -1. In other words, when a hyperbola appears with an average cosθ of -1 ⇒ 1 ⇒ -1, the reflection coefficient is negative.

[0040] Next, we will show an example where the reflection coefficient is positive. Regarding the cosine of the instantaneous phase of the multiple reflected waves shown in Figure 10, the cosine of the instantaneous phase θ of the reflected wave is approximately 1 for the positive hyperbola HB1', approximately -1 for the negative hyperbola HB2', and approximately 1 for the positive hyperbola HB3. In other words, when a hyperbola appears with an average cosθ of 1 ⇒ -1 ⇒ 1, the reflection coefficient is positive.

[0041] As explained above, the order (change) of the signs of the cosines of the instantaneous phases of the reflected waves differs for each hyperbola in the group of hyperbolae that make up the detected reflected waves depending on the sign of the reflection coefficient. The computer 30 of the exploration system 100 may estimate the signs of the reflection coefficients of the underground pipes based on the order of the signs of the cosines of the instantaneous phases of the reflected waves.

[0042] The computer 30 of the exploration system 100 may calculate the average of the cosines of the instantaneous phases along the shapes of the hyperbolic shapes for reflected waves of multiple hyperbolic shapes (group of hyperbolic shapes) adjacent in the time direction. More specifically, in FIG. 4, the computer 30 may calculate the average of the cosines of the instantaneous phases along the shapes of the hyperbolic shapes HA1, HA2, and HA3 for reflected waves of multiple (three or more, in this example, three) hyperbolic shapes HA1, HA2, and HA3 adjacent in the time direction. The average of the cosines of the instantaneous phases in the spatial direction may be calculated at two or more positions of the hyperbola. As described above, within a certain hyperbola, the cosines of the instantaneous phases are essentially all approximately 1 (approaching 1) or essentially all approximately -1 (approaching -1). Therefore, if the average of the cosines of the instantaneous phases is approximately 1 or approximately -1, it can be inferred that a hyperbolic reflected wave is generally present at the position where the average was calculated. On the other hand, if the average of the cosines of the instantaneous phases is not approximately 1 or approximately -1, it can be inferred that no reflected waves from the underground pipe are present at any of the positions where the average was calculated. The computer 30 may correct the hyperbola detection result based on the estimation result. In other words, the computer 30 may determine the change in the sign of the cosine of the instantaneous phase in the time direction based on the average of the cosines of the instantaneous phases. Therefore, the computer 30 can detect the planar position, depth, direction, reflection coefficient, etc. of the underground pipe with high accuracy. Referring to FIG. 5, when the computer 30 detects a three-dimensional hyperbolic wavefront from multiple images created by arranging the waveforms of the reflected waves for each scanning distance of the ground-penetrating radar 20, the computer 30 may calculate the average of the cosines of the instantaneous phases along the three-dimensional hyperbolic wavefront.

[0043] The computer 30 may create an image by arranging the absolute values ​​of the cosines of the instantaneous phases of the reflected waves for each scanning distance of the underground radar 20. The computer 30 may detect hyperbolas corresponding to underground pipes from the image. Referring to FIG. 10 , the absolute values ​​of the cosines of the instantaneous phases of the hyperbolas HA1, HA2, and HA3 are all approximately 1. In other words, the absolute value of the cosines is approximately 1 throughout the entire region of the group of hyperbolas HA. By searching for regions where the absolute value of the cosines is approximately 1, the computer 30 can easily detect the group of hyperbolas HA from an image created by arranging the waveforms of the reflected waves for each scanning distance of the underground radar 20. The same applies to the group of hyperbolas HB'.

[0044] Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications or alterations based on the present disclosure. Therefore, it should be noted that these modifications and alterations are included in the scope of the present invention. For example, the functions included in each means, step, etc. can be rearranged so as not to be logically inconsistent, and multiple means or steps can be combined or divided into one.

[0045] In the above-described embodiment, an example of a method for detecting underground pipes has been described with reference to Fig. 2. However, a configuration in which some steps included in the above-described operations or some operations included in one step are omitted within a range that is not logically inconsistent is also possible. Also, a configuration in which the order of multiple steps included in the above-described operations is reversed within a range that is not logically inconsistent is also possible.

[0046] Furthermore, in the above-described embodiment, the various means realized by the computer 30 have been described as software configurations, but at least some of the means may be conceptually comprised of software resources and / or hardware resources. [Explanation of symbols]

[0047] 100: Exploration System 10: Moving section 20: Ground-penetrating radar 30:コンピュータ 1000: Underground structures HA,HA',HB,HB': Hyperbolic group HA1, HA2, HA3, HB1, HB2, HB3, HB1', HB2', HB3': hyperbola t1,t2: vertex F1, F2: portrait d1: first direction d2: second direction

Claims

1. a reflected wave acquiring step of scanning the ground with the underground radar along a measurement line to acquire reflected waves of radio waves transmitted from the underground radar toward the ground at a plurality of measurement points; an underground pipe detection step of detecting reflected waves from underground pipes that appear in a hyperbolic shape from an image created by arranging the waveforms of the reflected waves for each scanning distance of the underground radar; a reflection coefficient sign estimation step of estimating the sign of the reflection coefficient of the underground buried pipe; A method for detecting underground pipes, including:

2. an instantaneous phase calculation step of calculating an instantaneous phase of the reflected wave; a cosine calculation step of calculating the cosine of the instantaneous phase; Further comprising: In the reflection coefficient sign estimating step, a sign of the reflection coefficient of the underground pipe is estimated based on a change in the sign of the cosine in the time direction. The method for detecting an underground pipe according to claim 1.

3. In the cosine calculation step, an average of cosines of instantaneous phases along each hyperbolic shape is calculated for a plurality of hyperbolic reflected waves adjacent in the time direction; 3. The underground pipe exploration method according to claim 2, wherein in said reflection coefficient sign estimating step, a change in the sign of said cosine in said time direction is obtained based on an average of said cosine.

4. In the underground pipe detection step, a plurality of images are obtained in a direction intersecting with the measurement line by arranging the waveforms of the reflected waves for each scanning distance of the underground radar, and when a hyperbolic reflected wave having vertices whose measurement points are located on a straight line is detected from the plurality of obtained images, the underground object corresponding to the hyperbolic reflected wave is determined to be the underground pipe. The method for exploring an underground buried pipe according to any one of claims 1 to 3.

5. The method further includes a depth estimation step of extracting reflected waves from underground pipes that appear in a hyperbolic shape from the image created by arranging the waveforms of the reflected waves for each scanning distance of the underground radar, estimating the propagation speed of the radio waves in the ground based on the shape of the hyperbolic reflected waves, and estimating the depth at which the underground pipes are installed. The method for exploring an underground buried pipe according to any one of claims 1 to 3.

6. 4. The underground buried pipe exploration method according to claim 1, wherein in the underground buried pipe detection step, a hyperbola corresponding to the underground buried pipe is detected from an image created by arranging the absolute values ​​of the cosine of the instantaneous phase of the reflected wave for each scanning distance of the underground radar.

7. On the computer, a reflected wave acquiring step of acquiring reflected waves of radio waves transmitted from the underground radar toward the ground at a plurality of measurement points by scanning the underground radar; an underground pipe detection step of detecting reflected waves from underground pipes that appear in a hyperbolic shape from an image created by arranging the waveforms of the reflected waves for each scanning distance of the underground radar; a reflection coefficient sign estimation step of estimating the sign of the reflection coefficient of the underground buried pipe; A program to execute.

Images