JP2018197763A - Measurement method and underground radar apparatus - Google Patents

Abstract

To improve accuracy of measurement using an underground radar.SOLUTION: A measurement method using an underground radar includes a first step of emitting an electromagnetic wave of the underground radar toward the underground from a transmission antenna installed on the ground surface, a second step of receiving a reflection wave of the electromagnetic wave at reception antennas arranged on the ground surface on the periphery with a position of the transmission antenna as a center, a third step of recording reception signals indicating intensity of the reflection wave received at the respective reception antennas in a plurality of different positions and a fourth step of acquiring information on a scatterer present in the underground by mutually comparing the reception signals recorded in the third step.SELECTED DRAWING: Figure 26

Description

  The present invention relates to a ground radar technology.

As a conventional underground radar technology, for example, a technology described in Non-Patent Document 1 is known. With reference to FIG. 37, the ground radar technology described in Non-Patent Document 1 will be described. FIG. 37 shows a cross-sectional view of the object in the ground by the ground radar and a radar image. FIG. 37 (a) shows antenna arrangement and electromagnetic wave reflection from the stratum boundary. The speed of electromagnetic waves in the ground varies depending on the relative dielectric constant and conductivity, which are material constants of the medium (soil). Since ground penetrating radar measures in the frequency range of 10 MHz or more, the properties of the medium mainly depend on the relative permittivity. In general, when the relative dielectric constant of the soil is epsilon _r, the electromagnetic wave velocity v [m / s: m / s] is expressed by the following equation (1). Where c is the speed of light in vacuum.

When the above equation (1) is modified, the following equation (2) is obtained. From the equation (2), the relative dielectric constant ε _r can be calculated from the electromagnetic wave velocity v.

  When the depth d [m] of the buried reflector is known as shown in FIG. 37A, the electromagnetic wave velocity v can be estimated from the arrival time τ of the reflected wave. Alternatively, when there is a reflector whose existence is clear, such as a metal tube, even if the depth of the buried reflector is unknown, the depth d and the electromagnetic wave velocity v of the reflector are reflected from the reflected waveform of the underground radar. Can be estimated simultaneously. The right figure of FIG.37 (b) shows the condition of the buried iron pipe (pipe). The left figure of FIG.37 (b) shows a ground penetrating radar image. In the example of the embedded pipe shown in FIG. 37 (b), when the transmitting antenna and the receiving antenna are at the horizontal position x, the arrival time τ of the reflected wave is expressed by the following equation (3) from the result of profile measurement. The The profile measurement is a measurement in which both the transmission antenna and the reception antenna of the subsurface radar are scanned on the ground.

In the above equation (3), unknown parameters are the buried position (depth d and horizontal position x ₀ ) of the metal tube and the electromagnetic wave velocity v. Horizontal position the metal tube is embedded x ₀ from the ground radar image shown in FIG. 37 (b) left, as upwardly convex hyperbolic vertex position is the horizontal position x ₀ of the metal tube, usually clear It is. Then, by changing the depth d in which the metal tube is embedded and the electromagnetic wave velocity v, the parameters are determined so that the theoretical arrival time fits the hyperbolic curve of the measured waveform as shown in FIG. Can be estimated at the same time as the depth d and the electromagnetic wave velocity v. From the estimated electromagnetic wave velocity v, the relative dielectric constant ε _r can be calculated by the above equation (2).

  Non-patent document 1 describes the ground penetrating radar technique with reference to FIG.

  Next, a method of operation (calibration and measurement) of the ground penetrating radar will be described. In the measurement using the ground penetrating radar, the relative permittivity of the soil in the range where the target buried object exists is acquired in advance. Then, the relative permittivity acquired in advance is set and calibrated to the ground penetrating radar before measurement, so that the response time axis of the ground penetrating radar image is measured even during the measurement while scanning the transmitting antenna and the receiving antenna. It can be observed by mapping to the depth. Here, the accuracy of the relative permittivity acquired in advance affects the measurement accuracy in the depth direction by the underground radar.

FIG. 38 is a flowchart of a conventional ground penetrating radar measurement method.
(Step S1001) The transmitting antenna and receiving antenna of the ground penetrating radar are arranged at the measurement position.
(Step S1002) An electromagnetic wave is transmitted from the transmission antenna.
(Step S1003) A reflected wave is received by a receiving antenna.
Steps S1001 to S1003 are measurement steps of the reflected wave. The step of measuring the reflected wave corresponds to the process until the electromagnetic wave is radiated from the transmitting antenna and the reflected wave is received by the receiving antenna in FIG.

(Step S1004) The relative dielectric constant is calculated from the received signal of the reflected wave received by the receiving antenna. The received signal of the reflected wave received by the receiving antenna represents the reflection of a known buried object buried in the ground.
(Step S1005) The reflected wave is processed using the calculated dielectric constant.
(Step S1006) The position and situation of the buried object are calculated from the processed reflected wave.
(Step S1007) The calculated position and status of the buried object are displayed.
Steps S1004 to S1007 are stages for calculating the relative permittivity and grasping the state of the buried object. This stage of calculating the dielectric constant corresponds to the point of deriving the dielectric constant from the depth and the arrival time in FIG. 37A and from the hyperbolic curve in FIG.

  As the calculation of the relative permittivity in the step S1004, the calculation of the formula (2) may be performed from the known depth d and the arrival time τ measured in FIG. The electromagnetic wave velocity v may be acquired by fitting the ground radar image of b) and the hyperbolic equation (3), and the above equation (2) may be calculated using the acquired electromagnetic wave velocity v.

Motoyuki Sato, “Physics Exploration Seminar“ Ground Radar ””, Tohoku University Research Center for Northeast Asia, July 2001, [Search April 17, 2015], Internet <URL: http: //cobalt.cneas. tohoku.ac.jp/users/sato/%92n%92%86%83%8C%81%5B%83_%82%C9%82%E6%82%E9%92n%89%BA%8Cv%91%AA (2001) revised.pdf>

  When measuring with a ground penetrating radar to grasp the state of the buried object from the ground, the accuracy of the relative dielectric constant of the soil in which the buried object is buried is important. However, there are various unnecessary scatterers in the ground where the buried object is embedded, and the reflected wave from the unnecessary scatterer deteriorates the accuracy of the measurement of the relative dielectric constant of the soil using the underground radar. For this reason, the accuracy of the relative permittivity of the soil becomes insufficient, and there is a possibility that the accuracy of the state of the buried object grasped from the result of measurement by the underground radar cannot be obtained sufficiently.

  With reference to FIG. 39, the problem in the relative permittivity measurement method related to FIG. 37 (a) described above in the conventional ground penetrating radar technology will be described. FIG. 39A shows antenna arrangement, electromagnetic wave reflection from the formation boundary, and electromagnetic wave reflection from unnecessary scatterers. Examples of unnecessary scatterers include multiple rocks. FIG. 39 (b) shows the time response of the reflection intensity by the received signal of the reflected wave received by the receiving antenna under the situation of FIG. 39 (a). In the graph of FIG. 39B, the horizontal axis represents time (t), and the vertical axis represents reflection intensity (I). In the graph of FIG. 39B, in addition to the component of reflection from the formation boundary surface, there is an unnecessary scattering component of the same degree as the reflection intensity of reflection from the formation boundary surface. In this case, it is difficult to specify the reflection at the formation boundary surface that is the object of measurement with high accuracy. For this reason, the accuracy of the arrival time τ of the reflected wave from the boundary surface of the formation cannot be increased, and the accuracy of measurement of the relative dielectric constant of the soil is deteriorated.

Also, in the relative permittivity measurement method related to FIG. 37 (b) described above in the conventional ground penetrating radar technology, the presence of unnecessary scatterers adversely affects the ground penetrating radar image, and the accuracy of the relative permittivity of the soil is reduced. to degrade. In the underground radar image shown in FIG. 37 (b), it can be confirmed as a convex hyperbolic pattern in which three pipes are reflected. However, if an unnecessary scatterer is present on the upper side (the ground side) of the pipe, the image is disturbed, so that the buried position (depth d and horizontal position x ₀ ) of the pipe is unclear, and the relative dielectric constant of the soil is accurately determined. I can't ask for it.

  In view of the above circumstances, an object of the present invention is to provide a technique capable of improving the accuracy of measurement using a ground penetrating radar.

  One aspect of the present invention is a measurement method using a ground penetrating radar, the first step of radiating electromagnetic waves of the ground penetrating radar toward the ground from a transmitting antenna disposed on the ground, and the transmitting antenna A second step of receiving the reflected wave of the electromagnetic wave by a receiving antenna arranged on the ground on the circumference centered on the position of the position, and a plurality of arrangements where the positions of the receiving antenna are different from each other. The third step of recording the received signal indicating the intensity of the reflected wave and the mutual comparison of the received signal recorded in the third step obtains information on the scatterer existing in the ground. And a fourth step.

  One embodiment of the present invention is a transmitting antenna that is disposed on the ground and radiates electromagnetic waves toward the ground, and is disposed on the ground on the circumference centered on the position of the transmitting antenna, and receives reflected waves of the electromagnetic waves. Recorded in the reception information recording unit, the reception information recording unit for recording the reception signal indicating the intensity of the reflected wave respectively received by the reception antenna in a plurality of arrangements having different positions of the reception antenna, and the reception information recording unit And a comparison unit that obtains information on the scatterers existing in the ground by performing mutual comparison of received signals.

  According to the present invention, it is possible to improve the accuracy of measurement using a ground penetrating radar.

The figure which shows the known information regarding the buried object which is a measuring object. Sectional drawing which shows a pair of antenna arrangement | positioning of 1st Embodiment. The top view which shows the antenna arrangement | positioning on the periphery of 1st Embodiment. Sectional drawing which shows a pair of antenna arrangement | positioning of 1st Embodiment. The figure which shows the example of the time response of the reflected wave of each antenna pair of 1st Embodiment. The figure which shows the result of having combined the time response of the reflected wave about the four antenna pairs of 1st Embodiment. The bird's-eye view which shows 4 pairs of antenna arrangement | positioning of 1st Embodiment. The figure which shows the example of the time response of the reflected wave of four antenna pairs of 1st Embodiment. The figure which shows the structure of the underground radar apparatus 130 of 1st Embodiment. The flowchart of the underground radar measuring method of 1st Embodiment. The figure which shows the structure of the underground radar apparatus 200 of 2nd Embodiment. The flowchart of the underground radar measuring method of 2nd Embodiment. The bird's-eye view which shows the example of a movement with the transmission antenna of 3rd Embodiment, and a receiving antenna. The figure which shows the example of the time response of the reflected wave in three measurement positions of 3rd Embodiment. The bird's-eye view which shows the example of a movement with the transmission antenna of 3rd Embodiment, and a receiving antenna. The top view which shows the example of a movement with the transmitting antenna of 3rd Embodiment, and a receiving antenna. The figure which shows the result of having combined the time response of the reflected wave of 3rd Embodiment. The bird's-eye view which shows the example of a movement with the transmission antenna of a comparison object of 3rd Embodiment, and a receiving antenna. The top view which shows the example of a movement with the transmitting antenna of a comparison object of 3rd Embodiment, and a receiving antenna. The figure which shows the result of having combined the time response of the reflected wave of the comparison object of 3rd Embodiment. The figure which shows the structure of the underground radar apparatus 350 of 3rd Embodiment. The flowchart of the underground radar measuring method of 3rd Embodiment. The figure which shows the example of arrangement | positioning with the transmission antenna of a modification of 3rd Embodiment, and a receiving antenna. The figure which shows the example of arrangement | positioning with the transmission antenna of a modification of 3rd Embodiment, and a receiving antenna. The figure which shows the example of arrangement | positioning with the transmission antenna of a modification of 3rd Embodiment, and a receiving antenna. The bird's-eye view which shows arrangement | positioning with the transmission antenna of a modification of 3rd Embodiment, and a receiving antenna. The top view which shows arrangement | positioning of the transmitting antenna and receiving antenna of the modification of 3rd Embodiment. The figure which shows the result of having combined the time response of the reflected wave of the modification of 3rd Embodiment. Explanatory drawing of the underground radar measuring method of 4th Embodiment. The figure which shows the structure of the underground radar apparatus 400 of 4th Embodiment. The figure which shows the example of arrangement | positioning with the transmission antenna of a modification of 4th Embodiment, and a receiving antenna. The figure which shows the example of arrangement | positioning with the transmission antenna of a modification of 4th Embodiment, and a receiving antenna. The figure which shows the example of arrangement | positioning with the transmission antenna of a modification of 4th Embodiment, and a receiving antenna. The flowchart of the underground radar measuring method of the modification of 4th Embodiment. Explanatory drawing of 5th Embodiment. Explanatory drawing of 5th Embodiment. Explanatory drawing of conventional underground radar technology. The flowchart of the conventional underground radar measuring method. Explanatory drawing of conventional underground radar technology.

  Hereinafter, a measurement method and a ground penetrating radar apparatus according to an embodiment will be described with reference to the drawings. In the following embodiments, the case where the relative permittivity is calculated will be described, but the present invention can be similarly applied to the case where the permittivity is calculated.

(First embodiment)
The first embodiment will be described with reference to FIGS. 1 to 10. FIG. 1 shows known information about an embedded object to be measured. The underground object (measurement object) shown in FIG. 1 is a manhole 100 provided for communication. The manhole 100 has a cylindrical shape with a radius a [m] and a height (depth) d [m], and a portion of the entrance to the ground (called a neck), and a rectangular parallelepiped that is the main body of the manhole 100 in the ground. It is composed of the space part. The main body of the manhole 100 is made of reinforced concrete and has a rectangular parallelepiped shape having a length L [m] and a width W [m]. The lid 101 at the neck of the manhole 100 has a disk shape with a radius a [m]. The ceiling (referred to as the upper floor board) of the manhole 100 has a thickness d ₀ [m]. The upper floor board of the manhole 100 is a reinforced concrete board (concrete board) in each of the ranges 102 and 103 on both sides of the manhole cover 101. Each of the ranges 102 and 103 has a rectangular shape having a length “L / 2−a” and a width W. The upper floor board of the manhole 100 is buried at a depth d from the ground. It is assumed that the detailed situation of the upper floor board of the manhole 100 is grasped from the ground using a ground penetrating radar. If the detailed situation of the upper floor board of the manhole 100 is known, the burden of maintenance inspection work on the manhole 100 can be greatly reduced. In order to grasp the state of the upper floor board of the manhole 100 in detail using the ground penetrating radar, it is necessary to accurately measure the relative permittivity of the ground (soil) where the electromagnetic wave transmitted from the ground penetrating radar propagates. is important. Hereinafter, a method for measuring the relative dielectric constant will be described by taking the manhole 100 shown in FIG. 1 as an example of measurement.

  FIG. 2 is a cross-sectional view showing a pair of antenna arrangements. FIG. 2 shows a pair of transmission antenna A1-1 and reception antenna A1-2. The transmission antenna A1-1 and the reception antenna A1-2 are arranged on the ground with an interval X [m]. The transmitting antenna A1-1 radiates electromagnetic waves from the ground radar toward the ground. The receiving antenna A1-2 receives the electromagnetic wave of the ground radar in order to measure the reflected wave of the electromagnetic wave radiated from the transmitting antenna A1-1. The place where each of the transmission antenna A1-1 and the reception antenna A1-2 is disposed is in the ranges 102 and 103 corresponding to the concrete plates existing at the depth d in the ground shown in FIG. Both the transmission antenna A1-1 and the reception antenna A1-2 are disposed in the same range of either the range 102 or the range 103. This is because if the transmitting antenna A1-1 and the receiving antenna A1-2 are separately arranged in the range 102 and the range 103, the electromagnetic waves radiated from the transmitting antenna A1-1 toward the ground are manholes. This is because propagation is hindered by the neck of the manhole 100 until it is reflected by the concrete surface of the upper floor board of the 100 or before it reaches the receiving antenna A1-2. The electromagnetic wave radiated from the transmitting antenna A1-1 toward the ground propagates through the soil and reaches the concrete surface of the upper floor board of the manhole 100. The reflected wave obtained by reflecting the electromagnetic wave that has reached the concrete surface of the upper floor board of the manhole 100 is received by the receiving antenna A1-2.

  FIG. 3 is a top view showing the antenna arrangement on the circumference. FIG. 3 shows four sets of transmission antennas and reception antennas as an example of the antenna arrangement on the circumference. In FIG. 3, a pair of a transmission antenna A1-1 and a reception antenna A1-2, a pair of a transmission antenna A2-1 and a reception antenna A2-2, and a pair of a transmission antenna A3-1 and a reception antenna A3-2 And a set of the transmission antenna A4-1 and the reception antenna A4-2 are arranged on the circumference of the same circle 111. In one set, a transmitting antenna is arranged at one end on one diameter of the circle 111 and a receiving antenna is arranged at the other end. In the circle 111, each pair of the transmission antenna and the reception antenna is arranged on a different diameter. The diameter of the circle 111 is X, and the antenna interval of each pair is X. FIG. 2 described above is a cross-sectional view taken along the alternate long and short dash line 112 in FIG. The center of the circle 111 corresponds to the alternate long and short dash line 110 in FIG. In each set, the underground radar electromagnetic wave radiated from the transmitting antenna toward the ground propagates through the soil, reaches the concrete surface of the upper floor board of the manhole 100, is reflected by the concrete surface, and is received as a reflected wave. Received by antenna.

  FIG. 4 is a cross-sectional view showing a pair of antenna arrangement, electromagnetic wave reflection from the concrete surface, and electromagnetic wave reflection from unnecessary scatterers. FIG. 4 shows a pair of transmission antenna A2-1 and reception antenna A2-2 shown in FIG. In FIG. 4, the reflection of electromagnetic waves by the concrete surface of the upper floor board of the manhole 100 and the reflection of electromagnetic waves by unnecessary scatterers such as rocks occur.

  Here, reflection of electromagnetic waves by the concrete surface of the upper floor board of the manhole 100 and reflection and scattering of electromagnetic waves by unnecessary scatterers will be described. The depth d at which the upper floor board of the manhole 100 is embedded is known. The arrangement of the transmission antenna A2-1 and the reception antenna A2-2 and the antenna interval X between the transmission antenna A2-1 and the reception antenna A2-2 are also known. Until the electromagnetic wave of the underground radar radiated from the transmitting antenna A2-1 to the ground propagates through the soil, is reflected by the concrete surface of the upper floor board of the manhole 100, and reaches the receiving antenna A2-2 as a reflected wave The propagation distance l [m] is expressed by the following equation (4).

  In the ranges 102 and 103 shown in FIG. 1 where the upper floor board of the manhole 100 exists, the reflection by the unnecessary scatterer does not satisfy the above formula (4). The above equation (4) is established for each set of transmitting antenna and receiving antenna shown in FIG. Therefore, it can be said that there is no unnecessary scatterer satisfying the above equation (4) for each pair of transmission antenna and reception antenna shown in FIG.

  It is assumed that the unnecessary scatterer satisfies the above-described formula (4) for only one set of the transmission antenna A2-1 and the reception antenna A2-2 shown in FIG. In this case, an unnecessary scatterer is arranged around an ellipse with the transmission antenna A2-1 and the reception antenna A2-2 as the focal points. In consideration of the reflection intensity in that case, it is necessary to have a reflecting surface along the ellipsoid. For this reason, it is considered that there are almost no unnecessary scatterers having a reflecting surface along the ellipsoid under the condition that the above formula (4) is satisfied and the reflection intensity is somewhat strong. Furthermore, “a set of transmission antenna A1-1 and reception antenna A1-2”, which is a set of other transmission antennas and reception antennas, and “a set of transmission antenna A3-1 and reception antenna A3-2”, Positions that satisfy all of the conditions that an unnecessary scatterer exists around each ellipse with the “set of transmitting antenna A4-1 and receiving antenna A4-2” as the respective focal points are extremely limited or all Since there is no position that satisfies the conditions at the same time, it can be said that there is no unnecessary scatterer at such a position.

Next, the electromagnetic wave of the underground radar radiated from the transmitting antenna A2-1 toward the ground propagates through the soil and is reflected by the concrete surface of the upper floor board of the manhole 100, and is reflected as a reflected wave to the receiving antenna A2-2. The arrival time until it reaches is τ. The relative dielectric constant ε _r of the soil is expressed by the following equation (5). However, c is the speed of light in vacuum “3.0 × 10 ⁸ [m / s]”.

From the propagation distance l and the arrival time τ, the relative permittivity ε _r of the soil can be calculated by the above equation (5). However, it is generally difficult to accurately determine the propagation distance l and the arrival time τ due to the influence of unnecessary scatterers shown in FIG.

  FIG. 5 shows an example of the time response of the reflected wave of each antenna pair. In the graph of FIG. 5, the horizontal axis represents time (t), and the vertical axis represents reflection intensity (I). FIG. 5 shows the four antenna pairs shown in FIG. 3, “A1 pair: combination of transmission antenna A1-1 and reception antenna A1-2” and “A2 pair: transmission antenna A2-1 and reception antenna. "A2-2 pair", "A3 pair: transmission antenna A3-1 and reception antenna A3-2", and "A4 pair: transmission antenna A4-1 and reception antenna A4-2" The time response of the reflected wave for each of is shown. The graph of each antenna pair is based on the received signal received by each receiving antenna in the underground state shown in FIG. That is, each graph of FIG. 5 shows the transmission antenna of each antenna pair in the underground state where the reflection of electromagnetic waves by the concrete surface of the upper floor board of the manhole 100 and the reflection of electromagnetic waves by unnecessary scatterers such as rocks occur. 2 shows a time change of a received signal received by a receiving antenna of each antenna pair of a reflected wave of an electromagnetic wave of a ground penetrating radar radiated from the ground to the ground.

  The solid line graph in FIG. 5 shows the time response of reflection of electromagnetic waves by the concrete surface of the upper floor board of the manhole 100. The broken line graph in FIG. 5 shows the time response of the reflection of electromagnetic waves by unnecessary scatterers. Regarding the reflection of electromagnetic waves by the concrete surface of the upper floor board of the manhole 100, all the antenna intervals of the four antenna pairs are the same as X, and the same reflection point (with a depth d of the concrete surface of the upper floor board of the manhole 100). Therefore, the arrival time τ is the same for all four antenna pairs.

  FIG. 6 shows the result of combining the time responses of reflected waves for the four antenna pairs shown in FIG. In the graph of FIG. 6, the horizontal axis is time (t), and the vertical axis is the combined reflection intensity (Ic). In FIG. 5, the time responses of the reflected waves for the four antenna pairs are individually shown in a graph, but in FIG. 6, the time responses of the reflected waves at the same time for each antenna pair are superimposed and synthesized. . The synthesis of the reflected wave by this superposition is performed by a process of adding the reflection intensity every time. The points to note in the process of combining the reflected waves are that the time axis of the reflected waves of each antenna pair is matched, the reflection of the buried object whose depth is known, here, the concrete surface (depth of the upper floor board of the manhole 100) Matching with the reflection time according to d). As a result, at the same time τ as the arrival time value, the reflected waves from the concrete surface of the upper floor board of the manhole 100 are overlapped and strengthened as the combined reflection intensity (Ic) (solid line graph in FIG. 6).

  On the other hand, in the result of the synthesis of the reflected wave by the unnecessary scatterer (broken line graph in FIG. 6), since the arrival times are different for each antenna pair, they are synthesized while being dispersed in time. ) Will not strengthen each other. This is because the unnecessary scatterer shown in FIG. 4 does not exist at an intermediate position between the transmission antenna and the reception antenna of each antenna pair, so that the transmission antenna of each antenna pair as shown in FIG. This is because when the position of the receiving antenna changes, the arrival time of the reflected wave by the unnecessary scatterer changes.

  If the unnecessary scatterer is present at the center of the circle 111 shown in FIG. 3, the unnecessary scatterer exists at an intermediate position between the transmission antennas and the reception antennas of the plurality of antenna pairs. As a result of the wave synthesis, the combined reflection intensity (Ic) is strengthened. However, it is rare that an unnecessary scatterer exists at such a position. In addition, if an unnecessary scatterer exists at the position of the condition, the reflection by the embedded object having a known depth is greatly affected. For example, with respect to a reflected wave from a buried object having a known depth, a phenomenon such as the absence of a reflected wave around the calculated arrival time occurs. As a result, by performing re-measurement by changing the positions of the transmitting antenna and the receiving antenna of the antenna pair, the combined reflection intensity (Ic) is not strengthened as a result of the synthesis of the reflected wave by the unnecessary scatterer. There is no.

As described above, by superimposing and synthesizing the time responses of the reflected waves at the same time for each antenna pair, the reflected waves caused by unnecessary scatterers do not increase as the combined reflection intensity (Ic), About the reflected wave by the concrete surface of the upper floor board of the manhole 100, it strengthens as synthetic | combination reflection intensity | strength (Ic). Therefore, in the graph of FIG. 6, it is possible to easily distinguish and separate components (unnecessary scattering components) of reflected waves from unnecessary scatterers. Thereby, only the component about the reflected wave by the concrete surface of the upper floor board of the manhole 100 can be extracted from the graph of FIG. Then, the arrival time τ for the reflected wave from the concrete surface of the upper floor board of the manhole 100 can be accurately known. The propagation distance l can be calculated by the above equation (4) from the antenna interval X and the depth d common to each antenna pair. Then, the relative dielectric constant ε _r of the soil can be accurately calculated from the arrival time τ and the propagation distance l by the above equation (5). Calibration of the ground penetrating radar is performed using the relative permittivity ε _r of the calculation result, thereby improving the accuracy of measurement by the ground penetrating radar.

  FIG. 7 is a bird's-eye view showing four antenna arrangements, the situation from the ground to the concrete surface in the ground, and each electromagnetic wave reflection. The four antenna pairs shown in FIG. 7 “A1 pair: set of transmitting antenna A1-1 and receiving antenna A1-2” and “A2 pair: set of transmitting antenna A2-1 and receiving antenna A2-2” , “A3 pair: pair of transmitting antenna A3-1 and receiving antenna A3-2” and “A4 pair: pair of transmitting antenna A4-1 and receiving antenna A4-2” are shown in FIG. It is an arrangement. Moreover, the reflection of the electromagnetic wave by the concrete surface of the upper floor board of the manhole 100 shown in FIG. 7 and the reflection of the electromagnetic wave by an unnecessary scatterer such as a rock are the same as those shown in FIGS. .

FIG. 8A shows an example of the time response of the reflected waves of the four antenna pairs shown in FIG. In the graph of FIG. 8A, the horizontal axis is time (t), and the vertical axis is reflection intensity (I). FIG. 8B shows the result of combining the time responses of the reflected waves for the four antenna pairs shown in FIG. In the graph of FIG. 8B, the horizontal axis is time (t), and the vertical axis is the combined reflection intensity (Ic). From the graph of FIG. 8B, a process of removing unnecessary scattering components is performed. In this unnecessary scattering component removal process, the reflected waves other than the time response of the reflected wave (solid line graph) appearing at time τ that strengthens as the combined reflected intensity (Ic) by combining the reflected waves of the four antenna pairs. Delete the time response (dotted line graph). Thus, from the graph of FIG. 8B, the arrival time τ for the reflected wave from the concrete surface of the upper floor board of the manhole 100 can be accurately known as the time τ to strengthen as the combined reflection intensity (Ic). Then, the propagation distance l is calculated by the above equation (4) from the antenna interval X and the depth d common to the four antenna pairs, and the above equation (5) is calculated from the arrival time τ and the propagation distance l. The relative permittivity ε _r of the soil in the ground shown in FIG. 7 can be calculated with high accuracy. Calibration of the ground penetrating radar is performed using the relative permittivity ε _r of the calculation result, and the ground measurement shown in FIG. 7 can be accurately performed by the ground penetrating radar after the calibration.

  Next, the apparatus configuration of the ground penetrating radar according to the present embodiment will be described. FIG. 9 shows the configuration of the underground radar apparatus 130. 9 includes a transmission unit 150, a reception unit 170, four antenna pairs “A1 pair: a combination of a transmission antenna A1-1 and a reception antenna A1-2”, and “A2 pair: transmission. "A set of antenna A2-1 and receiving antenna A2-2" and "A3 pair: a set of transmitting antenna A3-1 and receiving antenna A3-2" and "A4 pair: transmitting antenna A4-1 and receiving antenna A4-2" And a set. Each of the transmission antenna and the reception antenna of the four antenna pairs is arranged on the circumference of the same circle 111 as shown in FIG. The transmission unit 150 includes a transmission selection control unit 151 and an electromagnetic wave generation unit 152. The reception unit 170 includes a reception detection unit 171, a reception synthesis unit 172, a comparison unit 173, an unnecessary scattered wave removal / dielectric constant calculation unit 174, and a calibration / reception signal reprocessing unit 175.

  In the transmission unit 150, the transmission selection control unit 151 sequentially selects transmission antennas that emit electromagnetic waves from the transmission antennas A1-1, A2-1, A3-1, and A4-1 of the four antenna pairs. The transmission selection control unit 151 outputs a selection signal indicating the selected transmission antenna to the electromagnetic wave generation unit 152 and the reception unit 170. The selection signal input to the reception unit 170 is input to the reception synthesis unit 172 and the comparison unit 173. The electromagnetic wave generation unit 152 is connected to each of the transmission antennas A1-1, A2-1, A3-1, and A4-1 of the four antenna pairs. The electromagnetic wave generation unit 152 outputs an electromagnetic wave to the transmission antenna indicated by the selection signal input from the transmission selection control unit 151. Thereby, the electromagnetic wave of the underground radar is radiated from the transmission antenna indicated by the selection signal by the transmission selection control unit 151 toward the ground.

  In the reception unit 170, the reception detection unit 171 is connected to each of the reception antennas A1-2, A2-2, A3-2, and A4-2 of the four antenna pairs. The reception detector 171 receives signals received by the reception antennas A1-2, A2-2, A3-2, and A4-2 for each of the reception antennas A1-2, A2-2, A3-2, and A4-2. Detects electromagnetic waves from ground penetrating radar. The reception signals of the underground radar electromagnetic waves detected by the reception detector 171 for each of the reception antennas A1-2, A2-2, A3-2, and A4-2 are received antennas A1-2, A2-2, and A3-2. , A <b> 4-2 are output to the reception synthesis unit 172 and the comparison unit 173.

  The reception combining unit 172 is a selection signal input from the transmission selection control unit 151 among the reception signals of the reception antennas A1-2, A2-2, A3-2, and A4-2 input from the reception detection unit 171. Record the received signal of the receive antenna paired with the indicated transmit antenna. The reception combining unit 172 combines the recorded reception signals of the respective reception antennas A1-2, A2-2, A3-2, and A4-2. In this reception signal synthesis, as described with reference to FIGS. 5, 6, and 8, the reception signals of the reception antennas A <b> 1-2, A <b> 2-2, A <b> 3-2, and A <b> 4-4 are used. The reflection intensity (I) is added every time. In the addition of the reflection intensity (I), the time axis is adjusted by the time of reflection of the buried object whose depth is known, here, the reflection by the concrete surface (depth d) of the upper floor board of the manhole 100.

  The comparison unit 173 is indicated by a selection signal input from the transmission selection control unit 151 among the reception signals of the reception antennas A1-2, A2-2, A3-2, and A4-2 input from the reception detection unit 171. The received signal of the receiving antenna paired with the transmitting antenna is recorded. The comparison unit 173 performs a mutual comparison on the received signals of the respective reception antennas A1-2, A2-2, A3-2, and A4-2. If there is a reception signal that satisfies a predetermined abnormality determination condition for determining that the reception signal is abnormal as a result of the comparison, the comparison unit 173 sets the reception antenna of the reception signal to the reception synthesis unit 172. To notify. The reception synthesis unit 172 excludes the reception signal of the reception antenna notified from the comparison unit 173 from the reception signal synthesis target. This is due to the following reason. When a received signal having an abnormality in which reflection by the buried object to be measured, here, the concrete surface of the upper floor board of the manhole 100 is significantly different, is included in the received signal synthesis object, statistical processing (for example, Even if an average value or a median value is calculated, the processing result may be greatly affected. For this reason, it is possible to obtain a more accurate processing result by excluding the reception signal determined to be abnormal from the target of the reception signal synthesis. Furthermore, the accuracy of the ground radar image is improved by the processing after the synthesis of the received signals (required scattered wave removal / dielectric constant calculation processing, calibration / reception signal reprocessing).

  The unnecessary scattered wave removal / dielectric constant calculator 174 removes unnecessary scattered waves from the result of the reception signal synthesis by the reception synthesizer 172, and calculates the relative dielectric constant based on the result of removal of unnecessary scattered waves. The calculation method of the relative dielectric constant is the method described with reference to FIGS. 6 and 8 described above. The calibration / reception signal reprocessing unit 175 performs calibration using the relative dielectric constant calculated by the unnecessary scattered wave removal / dielectric constant calculation unit 174. The calibration / reception signal reprocessing unit 175 reprocesses the reception signal based on the calibration result.

  The operation of the ground penetrating radar apparatus 130 shown in FIG. 9 will be described with reference to FIG. FIG. 10 is a flowchart of the ground radar measurement method of the present embodiment.

(Step S101) The transmission selection control unit 151 selects one transmission antenna that radiates an electromagnetic wave from the transmission antennas A1-1, A2-1, A3-1, and A4-1 of the four antenna pairs.

(Step S102) The electromagnetic wave generation unit 152 outputs the electromagnetic wave to the transmission antenna selected by the transmission selection control unit 151. Thereby, the electromagnetic wave of the underground radar is radiated from the transmission antenna selected by the transmission selection control unit 151 toward the ground.

(Step S103) The reception detector 171 receives a reflected wave, which is an electromagnetic wave of a ground penetrating radar, by a receiving antenna paired with a transmitting antenna that has radiated an electromagnetic wave.

(Step S <b> 104) The reception synthesis unit 172 and the comparison unit 173 record the reception signal of the reflected wave received by the reception detection unit 171. When electromagnetic wave radiation is performed a plurality of times from the same transmission antenna, the reception signals of the reflected waves received by the reception detection unit 171 are combined each time, and the combined result is recorded. The synthesis of the reflected waves is performed by adding the intensities of the reflected waves respectively received by the transmitting antenna and the receiving antenna arranged at different positions.

(Step S105) The transmission selection control unit 151 determines whether or not the radiation of electromagnetic waves from all the transmission antennas A1-1, A2-1, A3-1, and A4-1 of the four antenna pairs has been completed. As a result, if completed, the process proceeds to step S106. On the other hand, if it is not completed, the process proceeds to step S101, and the transmission selection control unit 151 selects a transmission antenna that has not been radiated.

(Step S106) The reception combining unit 172 combines the recorded reception signals of the reception antennas A1-2, A2-2, A3-2, and A4-2. The reception combining unit 172 removes unnecessary scattered waves that are reflected waves from unnecessary scatterers from the combined result.

(Step S107) The comparison unit 173 records each reception received based on the “time of reflection from the concrete surface of the upper floor board of the manhole 100 (comparison target time)” obtained from the result of removing the unnecessary scattered wave in Step S106. A comparative evaluation of the received signals of the antennas A1-2, A2-2, A3-2, and A4-2 is performed. “Time of reflection from the concrete surface of the upper floor board of the manhole 100” in the recorded reception signals of the receiving antennas A1-2, A2-2, A3-2, and A4-2 is greatly different from the comparison target time. Determine whether. For example, it is determined whether or not the difference is a predetermined ratio (for example, 10%) or more. As a result of this determination, if the comparison target time greatly differs, the comparison unit 173 notifies the reception combining unit 172 of the reception antenna of the received signal determined to be significantly different from the comparison target time. Receiving this notification, the reception combining unit 172 removes the notified reception antenna from the reception signal combining target, and combines the recorded reception signals of the respective reception antennas. The result of combining the received signals is used for subsequent processing.

  Note that if there is no notification from the comparison unit 173 of reception antennas to be excluded from reception signal synthesis targets, the reception synthesis unit 172 does not synthesize reception signals in step S107. In this case, the result of combining received signals in step S106 is used for subsequent processing.

(Step S108) Unnecessary scattered wave removal / dielectric constant calculator 174 removes unnecessary scattered waves from the result of combining received signals by reception synthesizer 172, and calculates the relative dielectric constant based on the result of removal of unnecessary scattered waves. To do. Here, the result of combining the received signals is the result of adding the intensity of the reflected wave, and the arrival time of the reflected wave from the object is determined based on this result. The relative dielectric constant of the soil is calculated using the arrival time, the depth of the object, and the antenna interval.

(Step S109) The calibration / reception signal reprocessing unit 175 performs calibration using the relative dielectric constant calculated by the unnecessary scattered wave removal / dielectric constant calculation unit 174. The calibration / reception signal reprocessing unit 175 reprocesses the reception signal of the reflected wave based on the calibration result.

(Steps S110, S111) The ground penetrating radar apparatus 130 calculates the position and status of the embedded object from the received signal of the reflected wave reprocessed by the calibration / received signal reprocessing unit 175. The underground radar device 130 displays the calculated position and status of the buried object.

  According to the first embodiment described above, the electromagnetic wave of the ground penetrating radar is radiated from the transmitting antenna arranged on the ground toward the ground where there is an object with a known depth embedded in the soil. The reflected wave of the electromagnetic wave is received by the receiving antenna arranged on the ground at a constant antenna interval with the transmitting antenna. Next, the intensities of reflected waves respectively received by the reception antennas are added in a plurality of arrangements in which at least one of the transmission antenna and the reception antenna is different among the arrangements of the transmission antenna and the reception antenna. Next, the arrival time of the reflected wave from the object is determined based on the result of the addition of the intensity of the reflected wave. Next, the relative permittivity of the soil is calculated using the determination result of the arrival time, the depth of the object, and the antenna interval. Thereby, it is possible to reduce the influence of the reflected wave due to unnecessary scatterers existing in the soil and calculate the relative dielectric constant of the soil. Therefore, it is possible to improve the accuracy of measurement of the relative dielectric constant using the ground penetrating radar.

  According to the first embodiment, the transmission antenna and the reception antenna are arranged on the same circumference where the center exists on the ground directly above the object. Thereby, it is possible to easily receive the reflected wave radiated from the transmitting antenna and reflected at one point of the object at a plurality of positions.

(Second Embodiment)
The second embodiment will be described with reference to FIGS. 11 and 12. Also in the second embodiment, the underground manhole 100 shown in FIG. 1 is the measurement object, as in the first embodiment described above.

  FIG. 11 shows the configuration of the ground penetrating radar apparatus 200 of the second embodiment. The ground radar apparatus 200 illustrated in FIG. 11 includes a transmission unit 210, a reception unit 230, and one antenna pair “A1 pair: a combination of a transmission antenna A1-1 and a reception antenna A1-2”. In the underground radar apparatus 130 of the first embodiment shown in FIG. 9 described above, four antenna pairs “A1 pair: pair of transmitting antenna A1-1 and receiving antenna A1-2” and “A2 pair: transmitting antenna A2”. -1 and receiving antenna A2-2 "," A3 pair: transmitting antenna A3-1 and receiving antenna A3-2 "and" A4 pair: transmitting antenna A4-1 and receiving antenna A4-2. The transmitting antenna and the receiving antenna of each antenna pair are arranged on the circumference of the same circle 111 as shown in FIG. In the present embodiment, only “A1 pair: pair of transmitting antenna A1-1 and receiving antenna A1-2” is provided as an antenna pair, and the transmitting antenna A1-1 and the receiving antenna A1-2 are shown in FIG. Measurement is performed by sequentially moving to the position of each antenna pair shown. In FIG. 11, the positions of the transmitting antenna and the receiving antenna for the A2, A3 and A4 pairs are shown in parentheses.

  The transmission unit 210 includes a transmission control unit 211, an electromagnetic wave generation unit 212, and an antenna position control unit 213. The reception unit 230 includes a reception detection unit 231, a reception information recording unit 232, a reception synthesis unit 233, a comparison unit 234, an unnecessary scattered wave removal / dielectric constant calculation unit 235, and a calibration / reception signal reprocessing unit 236.

  In the transmission unit 210, the transmission control unit 211 gives an instruction to transmit the electromagnetic wave of the ground radar to the electromagnetic wave generation unit 212 and the antenna position control unit 213. The electromagnetic wave generation unit 212 is connected to the transmission antenna A1-1. The electromagnetic wave generation unit 212 outputs an electromagnetic wave to the transmission antenna A1-1 based on an instruction from the transmission control unit 211 and an input of antenna position information from the antenna position control unit 213. The antenna position control unit 213 sequentially moves the transmitting antenna A1-1 and the receiving antenna A1-2 to the position of each antenna pair shown in FIG. When the antenna position control unit 213 moves the transmitting antenna A1-1 and the receiving antenna A1-2 to the measurement position among the positions of each antenna pair shown in FIG. 3, the antenna position information indicating the measurement position is obtained. Output to the electromagnetic wave generator 212 and the receiver 230. The antenna position information input to the reception unit 230 is input to the reception information recording unit 232 and the comparison unit 234. The transmitting unit 210 emits an electromagnetic wave of a ground penetrating radar toward the ground from the transmitting antenna A1-1 at the measurement position indicated by the antenna position information among the positions of each antenna pair shown in FIG. . Further, the measurement positions are sequentially moved.

  Note that the movement between the transmitting antenna A1-1 and the receiving antenna A1-2 may be automatically performed by an antenna moving device (not shown in FIG. 11), or according to a movement instruction from the antenna position control unit 213. It may be done at.

  In the reception unit 230, the reception detection unit 231 is connected to the reception antenna A1-2. The reception detection unit 231 detects an electromagnetic wave of the ground radar from a signal received by the reception antenna A1-2. The reception signal of the electromagnetic wave of the ground radar detected by the reception detection unit 231 is output to the reception information recording unit 232 and the comparison unit 234.

  The reception information recording unit 232 records the reception signal input from the reception detection unit 231 in association with the antenna position information input from the transmission unit 210 to the reception unit 230. The reception combining unit 233 uses the antenna position information and the reception signal recorded in the reception information recording unit 232 to combine the reception signals at the measurement positions indicated by the antenna position information. In the combination of the received signals, the measurement positions of the reception antennas A1-2, A2-2, A3-2, and A4-2 of the four antenna pairs shown in FIG. The reflection intensity (I) of each received signal is added every time. In the addition of the reflection intensity (I), the time axis is adjusted by the time of reflection of the buried object whose depth is known, here, the reflection by the concrete surface (depth d) of the upper floor board of the manhole 100.

  The comparison unit 234 uses the antenna position information and the reception signal recorded in the reception information recording unit 232, and performs a mutual comparison for each reception signal at the measurement position indicated by the antenna position information. As a result of the comparison, when there is a reception signal that satisfies a predetermined abnormality determination condition for determining that the reception signal is abnormal, the comparison unit 234 determines the measurement position of the reception signal as the reception synthesis unit 233. To notify. The reception combining unit 233 excludes the reception signal at the measurement position notified from the comparison unit 234 from the above-described reception signal combining target. The reason for this is the same as that described for the comparison unit 173 of the first embodiment.

  Unnecessary scattered wave removal / dielectric constant calculator 235 removes unnecessary scattered waves from the result of combining received signals by reception synthesizer 233, and calculates the relative dielectric constant based on the result of removing unnecessary scattered waves. The calculation method of the relative dielectric constant is the same as that in the first embodiment. The calibration / reception signal reprocessing unit 236 performs calibration using the relative dielectric constant calculated by the unnecessary scattered wave removal / dielectric constant calculation unit 235. The calibration / reception signal reprocessing unit 236 reprocesses the reception signal based on the calibration result.

  The operation of the ground penetrating radar apparatus 200 shown in FIG. 11 will be described with reference to FIG. FIG. 12 is a flowchart of the underground radar measurement method of the present embodiment.

(Step S201) The antenna position control unit 213 places the transmission antenna A1-1 and the reception antenna A1-2 at the first measurement position. For example, the first measurement position is a pair of A1. The reception information recording unit 232 records the first measurement position based on the antenna position information.

(Step S202) The electromagnetic wave generation unit 212 outputs an electromagnetic wave to the transmission antenna A1-1. Thereby, the electromagnetic wave of the underground radar is radiated from the transmitting antenna A1-1 set at the measurement position toward the ground.

(Step S203) The reception detection unit 231 receives a reflected wave that is an electromagnetic wave of a ground penetrating radar by the reception antenna A1-2.

(Step S204) The reception information recording unit 232 records the reception signal of the reflected wave received by the reception detection unit 231. In addition, when electromagnetic wave radiation is performed a plurality of times from the same measurement position, the reception signals of the reflected waves received by the reception detection unit 231 are combined each time, and the combined result is recorded.

(Step S205) The antenna position control unit 213 determines whether or not the radiation of the electromagnetic wave from the transmission antenna A1-1 is completed at all the positions of the four antenna pairs shown in FIG. As a result, if completed, the process proceeds to step S208. On the other hand, if it is not completed, the process proceeds to step S206.

(Step S206) The reception information recording unit 232 records the reception position recorded in step S204 in association with the measurement position.

(Step S207) The antenna position control unit 213 moves the transmission antenna A1-1 and the reception antenna A1-2 to the next measurement position. For example, as shown in FIG. 11, the transmitting antenna A1-1 and the receiving antenna A1-2 are moved from the position of the A1 pair to the position of the A2 pair, that is, the positions (A2-1) and (A2-2) in FIG. And move. The reception information recording unit 232 records the next measurement position based on the antenna position information. Thereafter, the process returns to step S202.

(Step S <b> 208) The reception combining unit 233 combines the reception signals at the respective measurement positions recorded in the reception information recording unit 232. The reception combining unit 233 removes unnecessary scattered waves that are reflected waves from unnecessary scatterers from the combined result.

(Step S209) The comparison unit 234, based on the “time of reflection from the concrete surface of the upper floor board of the manhole 100 (comparison target time)” obtained from the result of the removal of unnecessary scattered waves in step S208, the reception information recording unit 232 A comparative evaluation of the received signal at each measurement position recorded in (1) is performed. It is determined whether the “time of reflection by the concrete surface of the upper floor board of the manhole 100” in the received signal at each measurement position is significantly different from the comparison target time. This comparative evaluation method is the same as the method in step S107 of FIG. 10 of the first embodiment described above. As a result of the comparison evaluation, if the comparison target time greatly differs, the comparison unit 234 notifies the reception combining unit 233 of the measurement position determined to be significantly different from the comparison target time. Receiving this notification, the reception combining unit 233 excludes the notified measurement position from the reception signal combining target, and combines the reception signals at the respective measurement positions recorded in the reception information recording unit 232. The result of combining the received signals is used for subsequent processing.

  Note that if the comparison unit 234 does not notify the measurement position to be excluded from the reception signal synthesis target, the reception synthesis unit 233 does not synthesize the reception signal in step S209. In this case, the result of combining received signals in step S208 is used for subsequent processing.

(Step S210) Unnecessary scattered wave removal / dielectric constant calculator 235 removes unnecessary scattered waves from the result of combining received signals by reception synthesizer 233, and calculates the relative dielectric constant based on the result of removal of unnecessary scattered waves. To do.

(Step S211) The calibration / reception signal reprocessing unit 236 performs calibration using the relative dielectric constant calculated by the unnecessary scattered wave removal / dielectric constant calculation unit 235. The calibration / reception signal reprocessing unit 236 reprocesses the reception signal of the reflected wave based on the calibration result.

(Steps S212 and S213) The underground radar apparatus 200 calculates the position and status of the embedded object from the received signal of the reflected wave reprocessed by the calibration / received signal reprocessing unit 236. The ground penetrating radar apparatus 200 displays the calculated position and status of the buried object.

  According to the second embodiment described above, as in the first embodiment, it is possible to reduce the influence of reflected waves caused by unnecessary scatterers existing in the soil and calculate the relative dielectric constant of the soil. Therefore, it is possible to improve the accuracy of measurement of the relative dielectric constant using the ground penetrating radar. Furthermore, similarly to the second embodiment, it is possible to easily receive a reflected wave radiated from the transmission antenna and reflected at one point of the object at a plurality of positions.

  Furthermore, according to the second embodiment, the pair of transmission antennas and reception antennas are moved on the same circumference where the center exists on the ground directly above the object. As a result, since only a pair of transmission antennas and reception antennas need be provided, cost can be reduced.

(Third embodiment)
A third embodiment will be described with reference to FIGS. Also in the third embodiment, the underground manhole 100 shown in FIG. 1 is an object to be measured, as in the first embodiment described above.

  FIG. 13 is a bird's eye view showing an example of movement between the transmission antenna and the reception antenna of the present embodiment. In the present embodiment, only one antenna pair “Aa pair: pair of transmitting antenna Aa-1 and receiving antenna Aa-2” is provided, and the transmitting antenna Aa-1 and the receiving antenna Aa-2 are provided at each measurement position. Move sequentially to perform the measurement. In FIG. 13, as three measurement positions, the position of “Aa pair” in which the transmission antenna Aa-1 and the reception antenna Aa-2 are shown, and “Ab pair: transmission antenna position Ab-1 in parentheses” are shown. And the position of the reception antenna position Ab-2 "and the position of" Ac pair: transmission antenna position Ac-1 and reception antenna position Ac-2 "shown in parentheses.

  The transmission antenna Aa-1 moves on the same line 301. Accordingly, each measurement position of the transmission antenna Aa-1 exists on the line 301. The receiving antenna Aa-2 moves on the same line 302. Therefore, each measurement position of the reception antenna Aa-2 exists on the line 301. At each measurement position, the antenna interval between the transmission antenna Aa-1 and the reception antenna Aa-2 is X and is constant. The lines 301 and 302 may be straight lines or curved lines. The transmission antenna Aa-1 and the reception antenna Aa-2 are arranged on the ground. Each measurement position exists within the range of the buried object to be measured. In FIG. 13, each measurement position exists within the range 102 or 103 of the upper floor board of the manhole 100 shown in FIG. The depth from the ground to the concrete surface of the upper floor board of the manhole 100 is d, which is common to each measurement position.

FIG. 14A shows an example of the time response of the reflected wave at the three measurement positions “Aa pair”, “Ab pair”, and “Ac pair” shown in FIG. In the graph of FIG. 14A, the horizontal axis is time (t), and the vertical axis is reflection intensity (I). FIG. 14B shows the result of combining the time responses of the reflected waves for the three measurement positions “Aa pair”, “Ab pair”, and “Ac pair” shown in FIG. In the graph of FIG. 14B, the horizontal axis is time (t), and the vertical axis is the combined reflection intensity (Ic). From the graph of FIG. 14B, a process for removing unnecessary scattering components is performed. In this unnecessary scattering component removal processing, the reflection appearing at time τ that strengthens as the combined reflection intensity (Ic) by combining the reflected waves for the three measurement positions “Aa pair”, “Ab pair”, and “Ac pair”. Other than the time response of the wave (solid line graph), the time response of the reflected wave (dashed line graph) is deleted. Thereby, from the graph of FIG.14 (b), the arrival time (tau) about the reflected wave by a concrete surface is correctly known as time (tau) to strengthen as synthetic reflection intensity (Ic). Then, the propagation distance l is calculated from the antenna distance X and the depth d common to the three measurement positions “Aa pair”, “Ab pair”, and “Ac pair” by the above equation (4), and the arrival time τ And the propagation distance l, the relative permittivity ε _r of the soil in the ground shown in FIG. Calibration of the ground penetrating radar is performed using the relative permittivity ε _r of the calculation result, and the ground measurement shown in FIG. 13 can be performed with high accuracy by the ground penetrating radar after the calibration.

  Here, the features of the present embodiment will be described with reference to FIGS. 15 to 20. 15 to 17 are explanatory diagrams of this embodiment. 18 to 20 are explanatory diagrams of objects to be compared with the present embodiment.

  First, an object to be compared with the present embodiment will be described with reference to FIGS. 18 and 19 show examples of movement of the transmission antenna and the reception antenna to be compared with the present embodiment, FIG. 18 is a bird's eye view, and FIG. 19 is a top view. The transmission antenna and the reception antenna in FIG. 18 are, for example, the transmission antenna and the reception antenna in the case illustrated in FIG. 18 and 19, the transmission antenna and the reception antenna, which are one antenna pair, are moved on the same line 331. 18 and 19, as the three measurement positions, “Ai pair: transmission antenna position Ai-1 and reception antenna position Ai-2”, and “Aii pair: transmission antenna position Aii-1 and reception antenna position Aii”. -2 "and the position of" Aiii pair: transmitting antenna position Aiii-1 and receiving antenna position Aiii-2 ". At each measurement position, the antenna interval between the transmission antenna and the reception antenna is the same. Each measurement position exists directly above an object (horizontal buried plate) buried in the ground. In FIGS. 18 and 19, the propagation path of the reflected wave (electromagnetic wave) by the object is indicated by a solid line arrow and the propagation path of the reflected wave (electromagnetic wave) by the unnecessary scatterer is indicated by a broken line arrow at each measurement position.

  In FIG. 19, an alternate long and short dash line ellipse indicates equidistant in the propagation path of reflection by the object at each measurement position. The dashed ellipse has a longer propagation distance than the one-dot chain ellipse, and indicates the equidistant range in the propagation path of reflection by unnecessary scatterers at each measurement position. And the unnecessary scatterer is shown by the point which the ellipse of the broken line about each measurement position overlaps.

FIG. 20 shows the result of synthesizing the time response of the reflected wave at each measurement position in FIGS. 18 and 19. In the graph of FIG. 20, the horizontal axis represents time (t), and the vertical axis represents the combined reflection intensity (Ic). Regarding the reflection at the object, the arrival time of the reflected wave is the same at τ ₂ at each measurement position because the object is a horizontal embedded plate. However, as shown in FIG. 20, the reflected wave from the object and the reflected wave from the unnecessary scatterer (unnecessary scattering) are strengthened as a combined reflection intensity (Ic) depending on the result of the combination. For this reason, it is impossible to determine which time is the arrival time of the reflected wave by the object, between the time τ ₁ related to unnecessary scattering and the time τ ₂ related to the object.

  Next, the present embodiment will be described with reference to FIGS. 15 to 17. 15 and 16 show examples of movement between the transmission antenna and the reception antenna of this embodiment, FIG. 15 is a bird's eye view, and FIG. 16 is a top view. In FIG. 15 and FIG. 16, the transmission antenna is moved on the line 301 and the reception antenna is moved on the line 302 among the transmission antenna and the reception antenna of one antenna pair as shown in FIG. 15 and 16, as the three measurement positions, “Aa pair: transmission antenna position Aa-1 and reception antenna position Aa-2” and “Ab pair: transmission antenna position Ab-1 and reception antenna position Ab” are shown. -2 "and the position of" Ac pair: transmitting antenna position Ac-1 and receiving antenna position Ac-2 ". At each measurement position, the antenna interval between the transmission antenna and the reception antenna is the same. Each measurement position exists directly above an object (horizontal buried plate) buried in the ground. 15 and FIG. 16, the propagation path of the reflected wave (electromagnetic wave) by the object is indicated by a solid line arrow for each measurement position, and the propagation path of the reflected wave (electromagnetic wave) by the unnecessary scatterer is indicated by a broken line arrow.

  In FIG. 16, an alternate long and short dash line ellipse indicates equidistant in the propagation path of reflection by the object at each measurement position. Dashed ellipses indicate equidistant ranges in the propagation path of reflection by unnecessary scatterers at each measurement position. The dashed ellipse has a longer propagation path than the one-dot chain ellipse. In the case of the present embodiment, as shown in FIG. 16, the propagation distance of the reflected wave by the unnecessary scatterer greatly varies depending on each measurement position. For example, at the measurement position of the Ab pair, the propagation distance of the reflected wave by the unnecessary scatterer is shorter than the measurement position of the Aa pair and the measurement position of the Ac pair. The fluctuation of the propagation distance of the reflected wave due to the unnecessary scatterer is caused by the method for moving the measurement position according to the present embodiment.

  FIG. 17 shows the result of synthesizing the time response of the reflected wave at each measurement position in FIGS. 15 and 16. In the graph of FIG. 17, the horizontal axis represents time (t), and the vertical axis represents the combined reflection intensity (Ic). Regarding the reflection at the object, since the object is a horizontal embedded plate, the arrival time of the reflected wave is the same at τ at each measurement position. On the other hand, as for the reflected wave (unnecessary scattering) by the unnecessary scatterer, the propagation distance varies at each measurement position as described above, so that the arrival time varies. As a result, the reflected wave from the object is remarkably increased as the combined reflection intensity (Ic) according to the result of the synthesis, so that it can be determined that the arrival time of the reflected wave from the object is time τ.

  FIG. 21 shows the configuration of the ground penetrating radar apparatus 350 of the third embodiment. 21 includes a transmission unit 360, a reception unit 380, and one antenna pair “Aa pair: a combination of a transmission antenna Aa-1 and a reception antenna Aa-2”. In the present embodiment, only “Aa pair: pair of transmission antenna Aa-1 and reception antenna Aa-2” is provided as an antenna pair, the transmission antenna Aa-1 on line 301 and the reception antenna Aa-2 on line 302. In the above, the measurement is performed by sequentially moving to each measurement position. In FIG. 21, as the three measurement positions, the position of “Aa pair” in which the transmission antenna Aa-1 and the reception antenna Aa-2 are shown, and “Ab pair: transmission antenna position Ab-1 in parentheses” are shown. And the position of the reception antenna position Ab-2 "and the position of" Ac pair: transmission antenna position Ac-1 and reception antenna position Ac-2 "shown in parentheses. Each measurement position is within the range of the object to be measured, here, the range 102 or 103 of the upper floor board of the manhole 100 shown in FIG. 1 above “rectangular shape of length“ L / 2−a ”and width W”. Exists.

  The transmission unit 360 includes a transmission control unit 361, an electromagnetic wave generation unit 362, and an antenna position control unit 363. The reception unit 380 includes a reception detection unit 381, a reception information recording unit 382, a reception synthesis unit 383, a comparison unit 384, an unnecessary scattered wave removal / dielectric constant calculation unit 385, and a calibration / reception signal reprocessing unit 386.

  In the transmission unit 360, the transmission control unit 361 issues an instruction to transmit the electromagnetic wave of the ground radar to the electromagnetic wave generation unit 362 and the antenna position control unit 363. The electromagnetic wave generation unit 362 is connected to the transmission antenna Aa-1. The electromagnetic wave generation unit 362 outputs an electromagnetic wave to the transmission antenna Aa-1 based on an instruction from the transmission control unit 361 and input of antenna position information from the antenna position control unit 363. The antenna position control unit 363 sequentially moves the transmission antenna Aa-1 and the reception antenna Aa-2 to each measurement position. When the antenna position control unit 363 moves the transmission antenna Aa-1 and the reception antenna Aa-2 to the measurement position, the antenna position control unit 363 outputs antenna position information indicating the measurement position to the electromagnetic wave generation unit 362 and the reception unit 380. The antenna position information input to the reception unit 380 is input to the reception information recording unit 382 and the comparison unit 384. The transmission unit 360 emits an electromagnetic wave of a ground penetrating radar toward the ground from the transmitting antenna Aa-1 at the measurement position indicated by the antenna position information among the measurement positions. Further, the measurement positions are sequentially moved.

  Note that the movement between the transmitting antenna Aa-1 and the receiving antenna Aa-2 may be automatically performed by an antenna moving device (not shown in FIG. 21), or according to a movement instruction from the antenna position control unit 363. It may be done at.

  In the reception unit 380, the reception detection unit 381 is connected to the reception antenna Aa-2. The reception detection unit 381 detects an electromagnetic wave of the ground radar from a signal received by the reception antenna Aa-2. The reception signal of the underground radar electromagnetic wave detected by the reception detection unit 381 is output to the reception information recording unit 382 and the comparison unit 384.

  The reception information recording unit 382 records the reception signal input from the reception detection unit 381 in association with the antenna position information input from the transmission unit 360 to the reception unit 380. The reception combining unit 383 combines the reception signals at the measurement positions indicated by the antenna position information, using the antenna position information and the reception signal recorded in the reception information recording unit 382. In this reception signal synthesis, the reflection intensity (I) of the reception signal at each measurement position is added for each time as in the first embodiment. In the addition of the reflection intensity (I), the time axis is adjusted to reflect the buried object whose depth is known, here, the reflection from the concrete surface (depth d) of the upper floor board of the manhole 100 shown in FIG. In time.

  The comparison unit 384 uses the antenna position information and the reception signal recorded in the reception information recording unit 382 to perform a mutual comparison for each reception signal at the measurement position indicated by the antenna position information. As a result of the comparison, when there is a reception signal that satisfies a predetermined abnormality determination condition for determining that the reception signal is abnormal, the comparison unit 384 determines the measurement position of the reception signal as the reception synthesis unit 383. To notify. The reception synthesis unit 383 excludes the reception signal at the measurement position notified from the comparison unit 384 from the reception signal synthesis target. The reason for this is the same as that described for the comparison unit 173 of the first embodiment.

  The unnecessary scattered wave removal / dielectric constant calculator 385 removes unnecessary scattered waves from the result of the reception signal synthesis by the reception synthesizer 383, and calculates the relative dielectric constant based on the result of the unnecessary scattered wave removal. The calculation method of the relative dielectric constant is the same as that in the first embodiment. The calibration / reception signal reprocessing unit 386 performs calibration using the relative dielectric constant calculated by the unnecessary scattered wave removal / dielectric constant calculation unit 385. The calibration / reception signal reprocessing unit 386 reprocesses the reception signal based on the calibration result.

  The operation of the ground penetrating radar apparatus 350 shown in FIG. 21 will be described with reference to FIG. FIG. 22 is a flowchart of the underground radar measurement method of the present embodiment.

(Step S301) The antenna position control unit 363 places the transmission antenna Aa-1 and the reception antenna Aa-2 at the first measurement position. The first measurement position is, for example, the position of the Aa pair. The reception information recording unit 382 records the first measurement position based on the antenna position information.

(Step S302) The electromagnetic wave generation unit 362 outputs an electromagnetic wave to the transmission antenna Aa-1. Thereby, the electromagnetic wave of the underground radar is radiated from the transmitting antenna Aa-1 set at the measurement position toward the ground.

(Step S303) The reception detection unit 381 receives a reflected wave that is an electromagnetic wave of a ground penetrating radar by the reception antenna Aa-2.

(Step S304) The reception information recording unit 382 records the reception signal of the reflected wave received by the reception detection unit 381. In addition, when electromagnetic wave radiation is performed a plurality of times from the same measurement position, the reception signals of the reflected waves received by the reception detection unit 381 are combined each time, and the combined result is recorded.

(Step S305) Whether the antenna position control unit 363 has completed the radiation of the electromagnetic wave from the transmission antenna Aa-1 at all of the positions “Aa pair”, “Ab pair”, and “Ac pair”. Judging. As a result, if completed, the process proceeds to step S308. On the other hand, if it is not completed, the process proceeds to step S306.

(Step S306) The reception information recording unit 382 records the measurement signal in association with the reception signal recorded in step S304.

(Step S307) The antenna position control unit 363 moves the transmission antenna Aa-1 and the reception antenna Aa-2 to the next measurement position. For example, as shown in FIG. 21, from the position of the Aa pair to the position of the Ab pair, that is, from the position of the transmitting antenna Aa-1 and the receiving antenna Aa-2 to the position of (Ab-1) and (Ab-2), respectively. The transmitting antenna Aa-1 and the receiving antenna Aa-2 are moved. The reception information recording unit 382 records the next measurement position based on the antenna position information. Thereafter, the process returns to step S302.

(Step S308) The reception combining unit 383 combines the reception signals at the respective measurement positions recorded in the reception information recording unit 382. The reception combining unit 383 removes unnecessary scattered waves that are reflected waves from unnecessary scatterers from the combined result.

(Step S309) The comparison unit 384 performs the reception information recording unit 382 based on the “time of reflection from the concrete surface of the upper floor board of the manhole 100 (comparison target time)” obtained from the result of removing the unnecessary scattered wave in step S308. A comparative evaluation of the received signal at each measurement position recorded in (1) is performed. It is determined whether the “time of reflection by the concrete surface of the upper floor board of the manhole 100” in the received signal at each measurement position is significantly different from the comparison target time. This comparative evaluation method is the same as the method in step S107 of FIG. 10 of the first embodiment described above. As a result of the comparison evaluation, if the comparison target time greatly differs, the comparison unit 384 notifies the reception combining unit 383 of the measurement position determined to be significantly different from the comparison target time. Receiving this notification, the reception combining unit 383 excludes the notified measurement position from the reception signal combining target, and combines the reception signals at the respective measurement positions recorded in the reception information recording unit 382. The result of combining the received signals is used for subsequent processing.

  Note that if the comparison unit 384 does not notify the measurement position to be excluded from the reception signal synthesis target, the reception synthesis unit 383 does not synthesize the reception signal in step S309. In this case, the result of combining received signals in step S308 is used for subsequent processing.

(Step S310) Unnecessary scattered wave removal / dielectric constant calculator 385 removes unnecessary scattered waves from the result of combining received signals by reception synthesizer 383, and calculates the relative dielectric constant based on the result of removing unnecessary scattered waves. To do.

(Step S311) The calibration / reception signal reprocessing unit 386 performs calibration using the relative dielectric constant calculated by the unnecessary scattered wave removal / dielectric constant calculation unit 385. The calibration / reception signal reprocessing unit 386 reprocesses the reception signal of the reflected wave based on the calibration result.

(Steps S <b> 312, S <b> 313) The underground radar apparatus 350 calculates the position and status of the embedded object from the reflected wave reception signal reprocessed by the calibration / reception signal reprocessing unit 386. The underground radar device 350 displays the calculated position and status of the buried object.

  Next, a modification of the third embodiment will be described with reference to FIGS. FIG. 23 to FIG. 25 are explanatory diagrams of modifications of the third embodiment. FIG. 23A, FIG. 24A, and FIG. 25A are plan views showing examples of the arrangement of transmission antennas and reception antennas. FIGS. 23B, 24 </ b> B, and 25 </ b> B are bird's-eye views showing examples of the arrangement of the transmission antenna and the reception antenna. In this modification, the position of the transmission antenna is fixed at Ao-1. The receiving antenna moves on the circumference of a circle 390 centered on the position Ao-1 of the transmitting antenna. In this modification, measurement is performed by moving the receiving antenna by 30 degrees as a central angle. FIG. 23 shows a measurement position Aa-2 as the first (first) measurement position of the receiving antenna. FIG. 24 shows a measurement position Ab-2 as the second measurement position of the reception antenna. FIG. 25 shows the measurement position Al-2 as the last (12th) measurement position of the receiving antenna.

  As shown in FIG. 23B, FIG. 24B, and FIG. 25B, the electromagnetic wave of the underground radar radiated from the transmitting antenna at the position Ao-1 toward the ground is the position Ao-1. And is reflected on the circumference of a circle whose center is half the length of the antenna interval between the transmitting antenna and the receiving antenna (that is, the length of half the radius of the circle 390). Received at measurement positions Aa-2, Ab-2,..., Al-2.

  In the modification of the third embodiment shown in FIGS. 23 to 25, the apparatus configuration is the same as that of the above-described underground radar apparatus 350 of FIG. 21, and the same as the above-described underground radar measurement method of FIG. It is a ground penetrating radar measurement method. However, the antenna position control unit 363 sequentially moves the position of the reception antenna from the first measurement position Aa-2 to the twelfth measurement position Al-2. Then, the electromagnetic wave generation unit 362 receives the antenna position information, and after the reception antennas are arranged at the measurement positions Aa-2, Ab-2,. An electromagnetic wave is output, and an electromagnetic wave of a ground penetrating radar is emitted from the transmitting antenna toward the ground.

  With reference to FIGS. 26 to 28, the characteristics of the modification of the third embodiment described above will be described. FIG. 26 to FIG. 28 are explanatory diagrams of modified examples of the above-described third embodiment. 26 and 27 show the arrangement of the transmission antenna and the reception antenna according to a modification of the third embodiment, FIG. 26 is a bird's eye view, and FIG. 27 is a top view.

  26 and 27, the transmission antenna is fixed at the position Ao-1. The measurement positions Aa-2, Ab-2,..., Al-2 of the receiving antenna are present on the circumference of a circle 390 centered on the position Ao-1 of the transmitting antenna. Therefore, at each measurement position of the receiving antenna, the antenna interval between the transmitting antenna and the receiving antenna is the same as the length of the radius of the circle 390. The transmitting antenna position Ao-1 and the receiving antenna measurement positions Aa-2, Ab-2,..., Al-2 are directly above the object (horizontal burying board) embedded in the ground. Exists. 26 and 27, the propagation path of the reflected wave (electromagnetic wave) by the object is indicated by a solid line arrow, and the propagation path of the reflected wave (electromagnetic wave) by the unnecessary scatterer is indicated by a broken line arrow.

  In FIG. 27, the alternate long and short dash line indicates that the propagation path of the reflection by the object at each measurement position of the receiving antenna is equidistant. However, the propagation distance of the reflected wave by the unnecessary scatterer varies greatly depending on each measurement position of the receiving antenna. For example, at the measurement position Ai-2 of the reception antenna, the propagation distance of the reflected wave by the unnecessary scatterer is shorter than that of the measurement position Aa-2 of the reception antenna. At the measurement position Ad-2 of the receiving antenna, the propagation distance of the reflected wave by the unnecessary scatterer is longer and becomes the longest. The fluctuation of the propagation distance of the reflected wave due to the unnecessary scatterer is caused by the measurement position moving method according to the modification of the third embodiment.

  FIG. 28 shows the result of synthesizing the time response of the reflected wave at each measurement position of the receiving antenna of FIGS. In the graph of FIG. 28, the horizontal axis represents time (t), and the vertical axis represents the combined reflection intensity (Ic). Regarding the reflection at the object, since the object is a horizontal buried plate, the arrival time of the reflected wave is the same at τ at each measurement position of the receiving antenna. On the other hand, with respect to the reflected wave (unnecessary scattering) due to the unnecessary scatterer, the propagation distance varies at each measurement position of the receiving antenna as described above, so that the arrival time varies. As a result, the reflected wave from the object is remarkably increased as the combined reflection intensity (Ic) according to the result of the synthesis, so that it can be determined that the arrival time of the reflected wave from the object is time τ.

  In FIGS. 23 to 25, the transmitting antenna is fixed as the center position of the circle 390 and the receiving antenna is moved on the circumference of the circle 390. However, the moving method may be reversed. That is, the receiving antenna may be fixed as the center position of the circle 390, and the transmitting antenna may be moved on the circumference of the circle 390.

  According to the third embodiment described above, similarly to the first embodiment, it is possible to reduce the influence of reflected waves caused by unnecessary scatterers existing in the soil and calculate the relative dielectric constant of the soil. Therefore, it is possible to improve the accuracy of measurement of the relative dielectric constant using the ground penetrating radar.

  Furthermore, according to the third embodiment, the transmission antenna and the reception antenna are arranged on different lines. Thereby, the reflected wave radiated | emitted from the transmission antenna and each reflected in the several position of the target object can be received separately.

(Fourth embodiment)
The fourth embodiment will be described with reference to FIGS. 29 and 30. FIG. Also in the fourth embodiment, the underground manhole 100 shown in FIG. 1 is an object to be measured, as in the first embodiment described above.

FIG. 29 is an explanatory diagram of a ground penetrating radar measurement method according to the fourth embodiment. In the fourth embodiment, measurement is performed on the same measurement object by changing the antenna interval between the transmission antenna and the reception antenna. FIG. 29A shows the first (first) antenna interval X _α and the propagation distance l _α of the reflected wave due to the concrete surface (depth d) of the upper floor board of the manhole 100. The FIG. 29 (b), the and second propagation distance of the reflected wave by the antenna interval X _beta and on the manhole 100 floorboards concrete surface (depth d) l _beta is shown. FIG. 29C shows the last (third) antenna interval X _γ and the propagation distance l _γ of the reflected wave due to the concrete surface (depth d) of the upper floor board of the manhole 100. The magnitude relationship between the antenna intervals is “X _α <X _β <X _γ ”. Further, the depth d is common and the same at each antenna interval. As a result, the magnitude relationship between the propagation distances between the antennas becomes “l _α <l _β <l _γ ”.

FIG. 29D shows an example of the time response of the reflected wave at the first (first) antenna interval _Xα . Arrival time of the reflected wave by the concrete surface of the floor plate above the antenna spacing X in the _alpha manhole 100 is tau _alpha. FIG. 29 (e) shows an example of the time response of the reflected wave at the second antenna interval _Xβ . Arrival time of the reflected wave by the concrete surface of the floor plate above the antenna spacing X in the _beta manhole 100 is tau _beta. FIG. 29 (f) shows an example of the time response of the reflected wave at the last (third) antenna interval _Xγ . Arrival time of the reflected wave by the concrete surface of the floor plate above the antenna spacing X in the _gamma manhole 100 is tau _gamma. Since the depth d is common and the same at each antenna interval, the propagation distances l _α , l _β , and l _{γ of} the electromagnetic waves radiated from the transmitting antenna change according to the antenna intervals X _α , X _β , and X _γ. . As a result, the arrival times τ _α , τ _β , τ _γ of reflected waves from the concrete surface of the upper floor plate of the manhole 100 change according to the antenna intervals X _α , X _β , X _γ . The magnitude relationship of the arrival time at each antenna interval is “τ _α <τ _β <τ _γ ”.

FIG. 29 (g) shows the result of synthesizing the time response of the reflected wave at each antenna interval of FIGS. 29 (d), (e), and (f). In this reflected wave synthesis process, the time axis is adjusted according to the interval between the antennas. From the antenna intervals X _α , X _β , X _γ and the common depth d, the propagation distances l _α , l _β , l _γ can be calculated by the above equation (4). From this, according to each antenna space | interval X ( _alpha) , X ( _beta) , X ( _gamma) , the time axis alignment in the reflected wave in each antenna space | interval is united with the time of the reflection by the concrete surface of the upper floor board of the manhole 100. As a result, as shown in FIG. 29 (g), the reflected waves from the concrete surface of the upper floor board of the manhole 100 overlap each other at each arrival time τ _α , τ _β , τ _γ , and strengthen as the combined reflection intensity (Ic). Result. As a result, the component (unnecessary scattering component) of the reflected wave from the unnecessary scatterer can be easily distinguished and separated, so that only the component of the reflected wave from the concrete surface of the upper floor board of the manhole 100 can be extracted. The arrival times τ _α , τ _β , and τ _γ corresponding to the antenna intervals X _α , X _β , and X _γ can be accurately determined. Therefore, from the arrival times τ _α , τ _β , τ _γ corresponding to each of the antenna intervals X _α , X _β , X _γ and the propagation distances l _α , l _β , l _γ , the above equation (5) The relative dielectric constant ε _r of can be calculated with high accuracy. Calibration of the ground penetrating radar is performed using the relative permittivity ε _r of the calculation result, thereby improving the accuracy of measurement by the ground penetrating radar.

FIG. 30 shows the configuration of the ground penetrating radar apparatus 400 of the fourth embodiment. GPR device 400 shown in FIG. 30, a transmission unit 410, a receiving unit 430, three antenna pairs and "set of transmit antennas of the antenna interval X _alpha and the receiving antenna" transmit antennas and "antenna spacing X _beta A “set of reception antennas” and a “set of transmission antennas and reception antennas with an antenna interval _Xγ ”. The transmitting antenna and the receiving antenna of each antenna pair are within the range of the buried object to be measured, here, the range 102 or 103 “length“ L / 2−a ”of the upper floor board of the manhole 100 shown in FIG. It is arranged on the ground within the “rectangular shape of width W”. The transmission unit 410 includes a transmission selection control unit 411 and an electromagnetic wave generation unit 412. The reception unit 430 includes a reception detection unit 431, a reception synthesis unit 432, a comparison unit 433, an unnecessary scattered wave removal / dielectric constant calculation unit 434, and a calibration / reception signal reprocessing unit 435.

In the transmission unit 410, the transmission selection control unit 411 includes the “antenna interval _Xα transmission antenna”, “antenna interval _Xβ transmission antenna”, and “antenna interval _Xγ transmission antenna” among the three antenna pairs. The transmitting antenna that radiates electromagnetic waves is sequentially selected. The transmission selection control unit 411 outputs antenna interval information indicating the antenna interval of the selected transmission antenna to the electromagnetic wave generation unit 412 and the reception unit 430. The selection signal input to the reception unit 430 is input to the reception synthesis unit 432 and the comparison unit 433. Electromagnetic wave generator 412 is connected to each of the three pairs of antennas as "transmitting antenna of antenna spacing X _alpha" and "transmitting antenna of the antenna interval X _beta" and "transmitting antenna of the antenna interval X _gamma". The electromagnetic wave generation unit 412 outputs an electromagnetic wave to the transmission antenna having the antenna interval indicated by the antenna interval information input from the transmission selection control unit 411. Thereby, the electromagnetic wave of the underground radar is radiated from the transmission antenna having the antenna interval indicated by the antenna interval information by the transmission selection control unit 411 toward the ground.

In the receiving unit 430, reception detecting unit 431, connected to each of the three pairs of antennas as "receiving antenna of the antenna interval X _alpha" and "receive antennas antenna spacing X _beta" and "receive antennas antenna spacing X _gamma" Is done. The reception detection unit 431 detects an electromagnetic wave of the ground radar for each reception antenna at each antenna interval from a signal received by the reception antenna at each antenna interval. The reception signal of the electromagnetic wave of the underground radar detected by the reception detection unit 431 for each reception antenna at each antenna interval is output to the reception synthesis unit 432 and the comparison unit 433 for each antenna interval.

The reception combining unit 432 has an antenna interval indicated by the antenna interval information input from the transmission selection control unit 411 among the received signals at the antenna intervals X _α , X _β , and X _γ input from the reception detection unit 171. Record the received signal. The reception synthesizer 432 synthesizes the received signals at the recorded antenna intervals X _α , X _β , and X _γ . In the synthesis of the received signal, as described by the above FIG. 29, the antenna spacing X _alpha, X _beta, and adjust the time axis in accordance with the X _gamma, the antenna spacing X _alpha, X _beta, received by the X _gamma The reflection intensity (I) of the signal is added every time.

Of the received signals at the antenna intervals X _α , X _β , and X _γ input from the reception detection unit 431, the comparison unit 433 is the antenna interval indicated by the antenna interval information input from the transmission selection control unit 411. Record the received signal. The comparison unit 433 performs a mutual comparison on the received signals at the respective recorded antenna intervals X _α , X _β , and X _γ . If there is a reception signal that satisfies a predetermined abnormality determination condition for determining that the reception signal is abnormal as a result of the comparison, the comparison unit 433 determines the antenna interval of the reception signal as the reception synthesis unit 432. To notify. The reception combining unit 432 excludes the reception signals at the antenna interval notified from the comparison unit 433 from the above-described reception signal combining targets. The reason for this is the same as that described for the comparison unit 173 of the first embodiment.

  The unnecessary scattered wave removal / dielectric constant calculator 434 removes unnecessary scattered waves from the result of the reception signal synthesis by the reception synthesizer 432, and calculates the relative dielectric constant based on the result of the unnecessary scattered wave removal. The calculation method of the relative dielectric constant is the same as that in the first embodiment. The calibration / reception signal reprocessing unit 435 performs calibration using the relative dielectric constant calculated by the unnecessary scattered wave removal / dielectric constant calculation unit 434. The calibration / reception signal reprocessing unit 435 reprocesses the reception signal based on the calibration result.

  Next, a modification of the fourth embodiment will be described with reference to FIGS. 31 to 34. FIG. 31 to FIG. 33 are explanatory diagrams of modified examples of the fourth embodiment. Fig.31 (a), FIG.32 (a), and Fig.33 (a) are top views which show the example of arrangement | positioning of a transmission antenna and a receiving antenna. FIG. 31B, FIG. 32B, and FIG. 33B are bird's-eye views showing examples of the arrangement of the transmission antenna and the reception antenna. In this modification, the transmitting antenna and the receiving antenna of each of the three antenna pairs are arranged on the circumference of the same circle (center 451 of the circle) whose antenna interval is a diameter.

In FIG. 31, the measurement positions of the transmission antennas and the reception antennas of each of the three groups are provided on the circumference of the same circle whose antenna interval _Xα is a diameter. In FIG. 31, a pair of a transmission antenna position A1-1 and a reception antenna position A1-2, a pair of a transmission antenna position A2-1 and a reception antenna position A2-2, and a transmission antenna position A3- Measurements are carried out in three groups: 1 and a position of the receiving antenna A3-2. In FIG. 32, measurement positions of the transmission antennas and the reception antennas of each of the three groups are provided on the circumference of the same circle whose antenna interval _Xβ is a diameter. In FIG. 32, a set of a transmission antenna position A4-1 and a reception antenna position A4-2, a set of a transmission antenna position A5-1 and a reception antenna position A5-2, and a transmission antenna position A6- Measurements are carried out in three sets of 1 and the position A6-2 of the receiving antenna. In Figure 33, on the circumference of the same circle of antenna spacing X _gamma is a diameter, providing a measurement position of a receiving antenna and three sets of each of the transmit antennas. In FIG. 33, a set of a transmission antenna position A7-1 and a reception antenna position A7-2, a combination of a transmission antenna position A8-1 and a reception antenna position A8-2, and a transmission antenna position A9- Measurements are performed in three groups, 1 and a set of the receiving antenna position A9-2.

For example, first successively arranged and each transmit antenna of three sets of antenna placement interval X _alpha and receiving antenna shown in FIG. 31, performed sequentially measured at each place. Secondly, the transmitting antenna and the receiving antenna are sequentially arranged in each of the three arrangements of the antenna interval _Xβ shown in FIG. 32, and the measurement is sequentially performed in each arrangement. Finally, the transmitting antenna and the receiving antenna are sequentially arranged in each of the three arrangements of the antenna interval _Xγ shown in FIG. 33, and the measurement is sequentially performed in each arrangement.

It should be noted that the arrangement of the transmitting antenna and the receiving antenna at each antenna interval X _α , X _β , X _γ is all within the range of the buried object to be measured, here the upper floor plate of the manhole 100 shown in FIG. Within the range 102 or 103 “rectangular shape of length“ L / 2−a ”and width W”, they are arranged on the ground.

A ground penetrating radar measurement method according to a modified example of the fourth embodiment will be described with reference to FIG. FIG. 34 is a flowchart of a ground penetrating radar measurement method according to a modification of the fourth embodiment. Here, only a pair of transmission antennas and reception antennas are used, and a pair of transmission antennas and reception antennas are sequentially moved to the respective arrangements shown in FIG. 31 to FIG. The measurement order of each arrangement is as follows. First, the orientation from the center 451 of the circle is fixed, and the measurement is performed at each antenna interval X _α , X _β , X _γ. Measurements are performed at fixed antenna intervals X _α , X _β , and X _γ .

(Step S401) A pair of transmission antennas and reception antennas are arranged in the first direction and the first antenna interval.

(Step S402) An electromagnetic wave of a ground penetrating radar is radiated from the transmitting antenna at the measurement position toward the ground.

(Step S403) A reflected wave that is an electromagnetic wave of the ground penetrating radar is received by the receiving antenna at the measurement position.

(Step S404) The received signal of the reflected wave received by the receiving antenna at the measurement position is recorded. In addition, when electromagnetic wave radiation is performed a plurality of times from the same measurement position, the received signals of the reflected waves received at each time are synthesized and the synthesized result is recorded.

(Step S405) It is determined whether or not the radiation of the electromagnetic wave from the transmitting antenna is completed at every antenna interval. As a result, if completed, the process proceeds to step S408. On the other hand, if it is not completed, the process proceeds to step S406.

(Step S406) The reception position recorded in step S404 is recorded in association with the measurement position.

(Step S407) The transmission antenna and the reception antenna are arranged at the next antenna interval. At this time, the direction is not changed. Thereafter, the process returns to step S402.

(Step S408) The transmission antenna and the reception antenna are arranged in the next direction and at the first antenna interval.

(Step S409) It is determined whether or not the radiation of the electromagnetic wave from the transmitting antenna is completed in all directions. As a result, if completed, the process proceeds to step S410. On the other hand, if it is not completed, the process returns to step S402.

(Step S410) The recorded reception signals at the respective measurement positions are synthesized. Unnecessary scattered waves, which are reflected by unnecessary scatterers, are removed from the synthesized result.

(Step S411) The reflected wave is comparatively evaluated. This comparative evaluation method is the same as the method in step S107 of FIG. 10 of the first embodiment described above.

(Step S412) Unnecessary scattered waves are removed from the result of combining received signals, and the relative dielectric constant is calculated based on the result of removing unwanted scattered waves.

(Step S413) Calibration is performed using the calculated dielectric constant. Based on the result of calibration, the received signal of the reflected wave is reprocessed.

(Steps S414 and S415) The position and status of the buried object are calculated from the reprocessed reflected wave reception signal. Displays the calculated position and status of the buried object.

  According to the above-described fourth embodiment, the electromagnetic wave of the ground penetrating radar is radiated from the transmitting antenna disposed on the ground toward the ground where the object embedded in the soil has a known depth. The reflected wave of the electromagnetic wave is received by a receiving antenna arranged on the ground at a known antenna interval from the transmitting antenna. Next, the intensities of the reflected waves respectively received by a plurality of receiving antennas arranged at different antenna intervals are added by adjusting the time axis according to the antenna intervals of the receiving antennas. Next, the arrival time of the reflected wave from the object is determined based on the result of the addition of the intensity of the reflected wave. Next, the relative permittivity of the soil is calculated using the determination result of the arrival time, the depth of the object, and the antenna interval. Thereby, it is possible to reduce the influence of the reflected wave due to unnecessary scatterers existing in the soil and calculate the relative dielectric constant of the soil. Therefore, it is possible to improve the accuracy of measurement of the relative dielectric constant using the ground penetrating radar. Furthermore, the relative dielectric constant can be calculated based on the reflected waves at a plurality of antenna intervals by changing the antenna interval between the transmitting antenna and the receiving antenna. This can further improve the accuracy of measurement of the relative dielectric constant.

According to the fourth embodiment, the intensities of the reflected waves respectively received by the reception antennas in a plurality of different arrangements having the same antenna interval among the arrangements of the transmission antenna and the reception antenna are added. Thereby, the relative permittivity can be calculated based on the reflected waves received at a plurality of positions at the same antenna interval. This can further improve the accuracy of measurement of the relative dielectric constant.
In the flowchart of the ground penetrating radar measurement method shown in FIG. 34, the direction of the transmitting antenna and the receiving antenna is changed after the direction of the transmitting antenna and the receiving antenna are fixed and the antenna interval is changed. That is, when the movement of the antenna position is specifically shown in FIGS. 31 to 33, the transmitting antennas are A1-1, A4-1, A7-1, A2-1, A5-1, A8-1, A3-1, The positions are moved in the order of A6-1, A9-1, and the receiving antennas correspond to the positions of the transmitting antennas A1-2, A4-2, A7-2, A2-2, A5-2, A8-2. , A3-2, A6-2, and A9-2 are moved in this order.
Unlike the method of moving the position of the antenna, the antenna interval may be changed after changing the azimuth of the transmitting antenna and the receiving antenna to all azimuths while maintaining the same antenna interval. In this case, as a specific movement of the antenna position in FIGS. 31 to 33, the transmitting antennas are A1-1, A2-1, A3-1, A4-1, A5-1, A6-1, A7-1, The positions are moved in the order of A8-1 and A9-1, and the receiving antennas correspond to the positions of the transmitting antennas A1-2, A2-2, A3-2, A4-2, A5-2, A6-2. , A7-2, A8-2, A9-2 are moved in this order.

(Fifth embodiment)
The fifth embodiment will be described with reference to FIGS. 35 and 36. The fifth embodiment is a ground radar measurement method when the depth of the object to be measured is unknown, for example, when the depth d of the manhole 100 shown in FIG. 1 is unknown.

35 and 36 are explanatory diagrams of the fifth embodiment. FIG. 35A and FIG. 36A are bird's-eye views showing examples of the arrangement of transmission antennas and reception antennas. In FIG. 35 (a), as in FIG. 31, the measurement positions of the transmission antennas and the reception antennas of each of the three groups are provided on the circumference of the same circle whose antenna interval _Xα is the diameter. In FIG. 36A, similarly to FIG. 33 described above, the measurement positions of the transmission antennas and the reception antennas of each of the three groups are provided on the circumference of the same circle whose antenna interval _Xγ is the diameter.

FIG. 35 (b) shows the result of synthesizing the time response of the reflected wave at each measurement position in FIG. 35 (a). From the result of this synthesis, the arrival time τ _α for the reflected wave from the concrete surface of the upper floor board of the manhole 100 to be measured is obtained with respect to the antenna interval X _α . FIG. 36B shows the result of synthesizing the time response of the reflected wave at each measurement position in FIG. From the result of this synthesis, the arrival time τ _γ for the reflected wave from the concrete surface of the upper floor board of the manhole 100 to be measured is obtained with respect to the antenna interval X _γ .

For antenna spacing X _alpha shown in FIG. 35, since the above equations (4) and (5), the relative dielectric constant epsilon _r is expressed by the following equation (6).

In the case of the antenna interval X _γ shown in FIG. 36, the relative permittivity ε _r is expressed by the following equation (7) from the above equations (4) and (5).

In the above equations (6) and (7), the unknown values are the relative permittivity ε _r and the depth d. In the case of the manhole 100 that is the same measurement target, the relative dielectric constant ε _r and the depth d, which are unknown values, are the same value. From this, the above equations (6) and (7) can be set as simultaneous equations. Here, the antenna intervals X _α and X _γ are known. The arrival times τ _α and τ _γ are obtained from the result of the above synthesis. As a result, the equation (6) and the equation (7) are transformed into the following equation (8).

  From the above equation (8), the depth d is expressed by the following equation (9).

Using the known antenna intervals X _α and X _γ and the arrival times τ _α and τ _γ obtained from the result of the above synthesis, the depth d can be calculated by the above equation (9).

Further, from the above formula (9) and the above formula (5), the relative dielectric constant ε _r is expressed by the following formula (10).

Using the known antenna intervals X _α , X _γ and the arrival times τ _α , τ _γ obtained from the result of the above synthesis, the relative dielectric constant ε _r can be calculated by the above equation (10). .

  According to the fifth embodiment described above, the electromagnetic wave of the ground penetrating radar is radiated from the transmitting antenna disposed on the ground toward the ground where the object embedded in the soil exists. The reflected wave of the electromagnetic wave is received by a receiving antenna arranged on the ground at a known antenna interval from the transmitting antenna. Next, the intensities of reflected waves respectively received by a plurality of receiving antennas arranged at different antenna intervals are added for each antenna interval. Next, the arrival time of the reflected wave from the object is determined for each antenna interval based on the result of the addition of the reflected wave intensity. Next, the relative permittivity of the soil is calculated using the result of the arrival time determined for each antenna interval and the antenna interval. Thereby, even when the depth of the object embedded in the soil is unknown, it is possible to calculate the relative permittivity of the soil while reducing the influence of the reflected wave due to the unnecessary scatterers existing in the soil. Therefore, it is possible to improve the accuracy of measurement of the relative dielectric constant using the ground penetrating radar. Moreover, the depth of the object embedded in the soil can also be calculated.

  If three or more antenna intervals are used, simultaneous equations can be established with the number of combinations, and it is possible to obtain relative dielectric constants for the number of combinations and statistically process the relative dielectric constants. . Thereby, the precision of a dielectric constant can be made higher.

As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the specific structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.
For example, the above-mentioned ground penetrating radar device may be realized by dedicated hardware, or configured by a computer system such as a personal computer, and a program for realizing the functions of each part of the ground penetrating radar device The function may be realized by executing.

  Moreover, an input device, a display device, or the like may be connected to the underground radar device as a peripheral device. Here, the input device refers to an input device such as a keyboard and a mouse. The display device refers to a CRT (Cathode Ray Tube), a liquid crystal display device or the like. The peripheral device may be connected directly to the ground penetrating radar device or may be connected via a communication line.

130,200,350,400 ... Ground radar apparatus, 150,210,360,410 ... transmitting unit, 151,411 ... transmission selection control unit, 152,212,362,412 ... electromagnetic wave generating unit, 170,230,380 , 430 ... reception unit, 171, 231, 381, 431 ... reception detection unit, 172, 233, 383, 432 ... reception synthesis unit, 173, 234, 384, 433 ... comparison unit, 174, 235, 385, 434 ... unnecessary Scattered wave removal / dielectric constant calculation unit, 175, 236, 386, 435 ... calibration / reception signal reprocessing unit, 211, 361 ... transmission control unit, 213, 363 ... antenna position control unit, 232, 382 ... reception information recording unit , A1-1, Aa-1 ... transmitting antenna, A1-2, Aa-2 ... receiving antenna

Claims (2)

A measurement method using a ground penetrating radar,
A first step of radiating an electromagnetic wave of the ground penetrating radar toward the ground from a transmitting antenna disposed on the ground;
A second step of receiving a reflected wave of the electromagnetic wave with a receiving antenna disposed on a ground surface around the position of the transmitting antenna;
A third step of recording a reception signal indicating the intensity of the reflected wave received by the reception antenna in a plurality of arrangements having different positions of the reception antenna;
A fourth step of obtaining information on the scatterers existing in the ground by performing a mutual comparison on the reception signals recorded in the third step;
Measuring method including A transmitting antenna arranged on the ground and radiating electromagnetic waves toward the ground;
A receiving antenna disposed on the ground on the circumference centered on the position of the transmitting antenna and receiving the reflected wave of the electromagnetic wave;
A reception information recording unit for recording a reception signal indicating the intensity of the reflected wave respectively received by the reception antenna in a plurality of arrangements having different positions of the reception antenna;
A comparison unit that obtains information on the scatterers existing in the ground by performing a mutual comparison on the reception signals recorded in the reception information recording unit;
A ground penetrating radar apparatus.

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