JPS63305273A - System for searching underground buried object - Google Patents

Abstract

PURPOSE:To obtain the accurate output of a searched image in a simple constitution, by computing the dielectric constant of a soil for every area, and performing synthetic aperture processing and correction in geology for every area by using the dielectric constant. CONSTITUTION:A monocycle pulse for example is transmitted from a transmitting antenna 4. The reflected wave is received with a receiving antenna 5. The output of the receiving antenna 5 is inputted into a controlling and processing means 7 through a receiver 6. The controlling and processing means 7 divides an underground cross section into a plurality of areas based on the discontinuous line of the profile data of the reflected wave. The dielectric constant of soil is computed for every area based on the profile data of the reflected wave. Synthetic aperture processing and correction in geology are performed for every area by using said data.

Description

[Detailed description of the invention] [Industrial field of application] This invention provides an underground object exploration method using a synthetic aperture method;
In particular, it relates to processing when the soil in which the target is buried is formed of vertical layers of different soil types.

[Conventional technology]

Figure 3 shows, for example, a paper published in October 1981 in the collection of papers of the Japan Society for Physical Exploration, pages 59 to 60 [W1 Underground exploration by magnetic wave reflection method (conventional underground buried object exploration method presented in February 1982). In the figure, 1 is a target such as a pipe, 2 is the soil in which this target 1 is buried, 3 is a transmitter, and 4
a transmitting antenna 5 that is connected to the transmitter 3 and emits a pulse signal from the transmitter 3 as an electromagnetic wave into the soil 2;
is a receiving antenna that receives reflected waves from the target object 1 of electromagnetic waves emitted from the transmitting antenna 4;
6 is a receiver connected to this receiving antenna 5.

Next, the operation will be explained. First, the interval between the transmitting antenna 4 and the receiving antenna 5 is adjusted to Yl, and the transmitter 3 sends out, for example, a monocycle pulse. This monocycle pulse is emitted from the transmitting antenna 4 into the soil 2 as an electromagnetic wave, and the reflected wave is reflected by the target 1 to the receiving antenna 5.
8th time, the time T from the transmission to the reception of this monocycle pulse is measured.
After moving the receiving antenna 5 to a position separated by Y2 from the transmitting antenna 4, the time T2 from transmission to reception of the monocycle pulse is measured in the same manner.

Here, the burial depth of target 1 is R1, and the relative dielectric constant of soil 2 is E5.
Then, there is a relationship (C/, /75) between the time T from signal transmission to reception and the interval Y between both antennas 4 and 5. Here, C is the speed of light.

Therefore, T is the measurement time T, , T2, and Y is the set interval Y3. By substituting Y2 and solving simultaneous equations with E5 and R as unknowns, the dielectric constant ε5 of the soil 2 can be determined.

Apart from such measurement of the relative dielectric constant ε5, the transmitting antenna 4 and the receiving antenna 5 are moved perpendicularly to the arrangement direction with the interval fixed, and monocycle pulses are transmitted and received, and the distance between the transmitting antenna 4 and the receiving antenna 5 is fixed. Collect reflected wave profile data of , and perform synthetic aperture processing on the reflected wave profile data using the relative permittivity E5 to obtain image data on a time scale, and perform geological correction using the above-mentioned relative permittivity E5. The time scale is converted into a length scale, and an exploration image output of the target object 1 buried in the soil 2 is obtained from this image data.

[Problem that the invention seeks to solve]

Since the conventional underground object exploration method is configured as described above, the measurement of the relative dielectric constant of the soil in which the target is buried is performed as a completely separate task from the measurement for collecting reflected wave profile data. In addition, because the original soil is not used to backfill excavated trenches during construction work such as repairing buried pipes, etc. or new additional burial, etc. However, it is difficult to understand the layer structure of the soil in which the target is buried and the relative permittivity of each layer. , therefore,
There are also problems such as the output of target exploration images obtained by performing synthetic aperture processing, geological correction, etc., lacks accuracy.

This invention was made to solve the above-mentioned problems, and allows accurate exploration image output to be obtained.

The purpose of this invention is to obtain an underground object exploration method that eliminates the need for special data collection work just to determine the dielectric constant of the soil in which a target is buried.

[Means for solving problems]

The underground buried object exploration method according to the present invention divides the ground plane into a plurality of areas based on discontinuous lines of collected reflected wave profile data for each ground plane, and sets a dielectric constant for each of the areas. Synthetic aperture processing is performed on the reflected wave profile data while sequentially changing the value, and the relative permittivity of the soil for each area is determined from the evaluation of the results. Synthetic aperture processing, geological correction, etc. to obtain exploration image output are performed for each area.

[Effect]

In the underground buried object exploration method of this invention, the ground surface is divided into multiple areas according to discontinuous lines of reflected wave profile data, the relative permittivity of the soil is determined for each area, and the relative permittivity obtained is By performing synthetic aperture processing, geological correction, etc. for each area using 11) By performing synthetic aperture processing on the reflected wave profile data collected for the purpose of determining the relative permittivity while changing the set value of the relative permittivity, it is possible to eliminate the need for special measurement work just for determining the relative permittivity of the soil. did.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, STI is the step of dividing the ground plane into a plurality of areas, Sr1 is the step of calculating the relative dielectric constant E51 of the soil for each area following step ST1, and Sr1 is the step of calculating the relative dielectric constant E51 of the soil for each area following step ST2. 5T-6 is a step of detecting completion, Sr1 is a step of performing synthetic aperture processing of the reflected wave profile data for each area following step ST3, Sr1 is a step of detecting completion of processing in all areas following Sr1. A step of performing geological correction processing for each area following step ST5, S
r1 is a step that detects the completion of processing in all areas following step ST6, from the branch of step ST3 to step ST2, from the branch of step ST5 to step ST4, and from the branch of step ST7 to step ST
The processing is returned to step 6. Further, 11 is collected reflected wave profile data, 12 is image data on a time scale obtained as a result of synthetic aperture processing, and 13 is image data on a length scale obtained by geologically correcting it.

Next, the operation will be explained. First, the underground screen! , It is collected the reflected wave profile data 11 of the order.

1. FIG. 2 is an explanatory diagram for explaining the collection of reflected wave profile data, and in the figure, numerals 1 to 6 correspond to the conventional ones indicated by the same reference numerals in FIG. 3. Further, 7 is a control processing means for performing synthetic aperture processing on the reflected wave profile data to create an exploration image output of the target, 8 is an output display means for displaying the reflected wave profile data, exploration image output, etc., and 9 is the control This is an input means for inputting operation information, etc. to the means. The mutual spacing between the transmitting antenna 4 and the receiving antenna 5 is fixed to a predetermined value y, and the transmitting antenna 4 and the receiving antenna 5 are moved at a constant pitch in a direction indicated by an arrow X perpendicular to the direction in which both the antennas 4 and 5 are arranged. Each time it moves, for example, a monocycle pulse is emitted from the transmitting antenna 4, and its reflected wave is received by the receiving antenna 5. Therefore, the reflected wave from the target object 1 returns in the shortest time when both antennas 4.5 are directly above the target object 1.

If there is a deviation from this, the time will become longer depending on the amount of deviation. That is, if the depth of target 1 is R1, the mutual spacing between both antennas 4 and 5 is y, the relative dielectric constant of ±2 where target 1 is buried is ε5, and the speed of light is C, then What is the distance between X and the line connecting both antennas 4.5 from directly above (hereinafter referred to as antenna position) and the time t until the reflected wave returns?

2 Jx”−+’K”H theory Shi= (C/Es) There is a relationship between This formula is This can be transformed into Let be the vertex (however, do not consider the negative region of the time axis), death It is a hyperbola with asymptote.

The reflected wave profile data shown as 11 in Figure 1 shows the zero-crossing point of the ideal waveform of the reflected wave at each measurement point when the target 1 is buried in three different layers of soil, one by one. Only the reflected waves directly above each target object 1 are illustrated by solid lines. The broken line connecting these zero-crossing points does not form a smooth hyperbola due to differences in the propagation speed of electromagnetic waves due to differences in the dielectric constant of the soil in each layer, or due to refraction, etc., and discontinuities occur at the boundaries of each layer. There is. Also shown on the top side is a waveform resulting from direct computation from the transmitting antenna 4 to the receiving antenna 5.

Reflected wave profile data 1 collected in this way
1 is displayed on the output display device 8 and is used for area division of the ground plane in step STI. That is, the operator who observed the reflected wave profile data displayed on the output display device 8 identifies the portion where the line connecting the zero crossing points of the reflected wave is discontinuous, and calculates the coordinates x1 and x2 of the discontinuous line. Enter the following using the input means 9. Based on this discontinuous line P@mark Xll X, the control processing means 7 divides the ground plane into a first area below the coordinate Divide into three areas into the third area.

Next, in step ST2, the relative dielectric constant εs1 of the soil in the first area is calculated. That is, in step ST2, first, the setting value of the relative permittivity is sequentially changed from the initial value by an appropriate method, and for each setting value, the reflected wave profile data in the first area is subjected to synthetic aperture processing. Obtain image data.

As mentioned above, the shape of the hyperbola changes depending on the relative permittivity, so if the set value of the relative permittivity is far from the relative permittivity ε51 of the soil in the first area, the shape of the hyperbola will change greatly. In contrast, only a small portion of data can be accumulated at the vertex by performing one composite amount processing, and the target spot on the image data becomes extremely low.

However, when the set value approaches the dielectric constant ε51 of the soil in the first area, the shapes of the sliding curves become similar, and if they become equal, they match, and data of many parts are accumulated at the apex, and the above-mentioned A highly sharp target spot can be obtained on the image data. The sharpness of this target spot is evaluated to calculate the ratio vI electric rate s1 of the soil in the first area. Here, as a method for evaluating the sharpness of the target spot,
The target spot is sliced at a predetermined level and the ratio of its cross-sectional area to height is calculated. Alternatively, various methods can be considered, such as normalizing the height of the target spot to the same value between each image data and comparing the volumes.

In step ST3, it is determined whether this process has been completed in all areas, and thereafter, exactly the same process is performed in the second area and the third area.

The dielectric standard E5□*fs3 of the soil in each area is calculated. When the completion of this process in all areas is detected in step ST3, the process moves to step ST4, and a synthetic aperture process is performed on the reflected wave profile data to obtain an exploration image output.

In step ST4, first, the reflected wave profile data of the first area is synthesized based on the dielectric constant εs1 of the soil in the first area calculated in step ST2, and the data is accumulated at the apex of the hyperbola. A target spot is formed based on the weight of the image. Thereafter, similar processing is performed for the second area and the third area by the action of step ST5, and image data shown at 12 in FIG. 1 is obtained.

In this image data 12, the weight of the image of each target spot is displayed as the density of black dots.

The vertical axis of the obtained image data 12 is the time scale,
In order to convert this into a length scale that displays the buried depth of the target, geological correction is sequentially performed for each area in steps ST6 and ST7. That is, the relative dielectric constant ε5□ of the soil in each area calculated in step ST2
~ε5. The propagation speed of underground electromagnetic waves in each area is determined using obtain.

This image data 13 is output processed for easy viewing and displayed on the output display means 8 as an exploration image output.

In the above embodiment, a case has been described in which the ground plane is divided into three areas, but the area is divided into a predetermined number of areas depending on the number of discontinuous lines.

〔Effect of the invention〕

As described above, according to the present invention, a ground plane is divided into a plurality of areas based on discontinuous lines of reflected wave profile data, and the relative dielectric constant of the soil is calculated for each area from the reflected wave profile data. Since the configuration is such that synthetic aperture processing and geological correction are performed for each area using this, there is no need for special measurement work just to determine the above-mentioned relative dielectric constant, and furthermore, it is possible to eliminate the need for buried targets. Even if the soil has a multi-IAt layer structure in the vertical direction, accurate exploration image output can be obtained.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing an underground object exploration method according to an embodiment of the present invention, FIG. 2 is an explanatory diagram for explaining the collection of reflected wave profile data, and FIG. 3 is a conventional underground object exploration method. It is an explanatory diagram showing a method. 1 is the target, 2 is the soil where target 1 is buried, 3 is the transmitter, 4 is the transmitting antenna, and 5 is the receiving antenna. 6 is a receiver, 7 is a control processing means, 8 is an output display means, 9
is an input means. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Representative Masuo Oiwa Figure 1 Figure 2 Figure 9: AJ) Sputum

Claims (1)

[Claims] Transmitting antennas and receiving antennas arranged at predetermined intervals,
While moving along the ground surface at a constant pitch in a direction substantially perpendicular to the arrangement direction, the receiving antenna receives the reflected wave of the pulse signal transmitted from the transmitting antenna toward the ground. means for collecting unit reflected wave profile data, control processing means for performing synthetic aperture processing on the reflected wave profile data to create an exploration image output of the target, and collecting the reflected wave profile data, exploration image output, etc. In the underground buried object exploration device, the apparatus includes an output display means for displaying information, and an input means for inputting operation information etc. to the control processing means, wherein the control processing means outputs the reflected wave displayed on the output display means. The relative permittivity is divided into a plurality of areas based on the discontinuous line of the profile data and according to the coordinate information input from the input means, and is set sequentially in each of the areas while appropriately changing the relative permittivity. Synthetic aperture processing is performed on the reflected wave profile data for each set value of An underground buried object exploration method characterized in that synthetic aperture processing and geological correction processing are performed for each of the areas using the actual dielectric constant of the corresponding soil.