JPH04128683A - Underground specific inductive capacity measuring device - Google Patents

Abstract

PURPOSE:To quickly calculate the underground specific inductive capacity with high accuracy by radiating electromagnetic radio waves from the ground surface into the ground, and determining the specific inductive capacity which corresponds to the measured impedance by calculating operation. CONSTITUTION:An antenna 12 is installed on the ground surface of a place at which underground specific inductive capacity is known. By control of a calculation means 14, electromagnetic radio waves are then radiated through an impedance measuring means 13 from the antenna 12, and reflected waves from the ground are received by the antenna 12. According to the received results, the impedance measuring means 13 measures impedance in the ground in which the specific induction capacity is known. Then, the calculation means 14 makes an impedance/specific inductive capacity- conversion table regarding the specific induction capacity in the ground and the above measured impedance as correspondence data, and stores this table in memory, etc. Thus, by storing a number of values of impedance and corresponding specific inductive capacity measured by installing the antenna 12 on the ground surface at which the specific inductive capacity is known in the memory in the calculation means 14 as an impedance/specific inductive capacity-conversion table, the accuracy of calculating the specific inductive capacity can be improved.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applicable to measuring the physical properties of the earth and exploring underground objects by measuring the relative permittivity of the earth. This article relates to an underground dielectric constant measuring device to be used.

[Conventional technology]

Figure 3 shows, for example, [Simple measurement method for electrical properties of soil] (2)
This is a circuit diagram showing a conventional underground dielectric constant measurement device presented at the 0th Soil Engineering Research Presentation D-2 June 1985. In the figure, 1 is a high frequency oscillator and 2 is a reference capacitor. , 3 is a reference resistor, 4 is soil as a sample, 5 is an electrode plate sandwiching the soil 4, and 6 is a high frequency transmission through the electrode plate 5 sandwiching ±4 through either the reference capacitor 2 or the reference resistor 3. Vessel 1
This is a switch for selectively connecting to.

Next, the operation will be explained.

First, the soil 4 whose dielectric constant is to be determined is sampled and placed between the electrode plates 5. In this case, the spacing between the electrode plates 5 is always maintained at a predetermined value. Next, the reference capacitor 2 is selected by the switch 6, a high frequency current is output from the high frequency oscillator 1, and this is applied to the series circuit of the selected reference capacitor 2 and the soil 4. ] The voltage across −■. , the voltage across the reference capacitor 2 1, and the voltage V2 across each electrode plate 5 are measured with a voltmeter or the like.The voltages v0, V, , V thus measured.

has a vector relationship as shown in Fig. 4, and @pressure V1
If the capacitance of the reference capacitor 2 is C2, the component a that is in phase with the voltage V2 of is a=C,/C□ (1).On the other hand, the propagation speed of the electromagnetic wave underground is , C is the speed of light, E,
As the relative permittivity of the ground, V given c/4τ
...It is approximated by (2). Therefore, from the electrostatic capacitance C2 of ±4 obtained from equation (1), the spacing d of the electrode plates 5, and the area S, the relative permittivity E of ±4 is calculated as follows:
It becomes S. However, E is the dielectric constant of vacuum. Further, the dielectric constant obtained in this way can be used as a standard for determining the presence or absence of underground objects.

[Problem to be solved by the invention]

Conventional underground relative permittivity measurement equipment is configured as described above, so in order to obtain the relative permittivity of the soil, it is necessary to collect soil samples from the site. Not only would it be necessary to destroy the paved surface in places where the pavement was used, but it would also be difficult to work, as it would be necessary to collect soil samples from many measurement points in order to determine the average dielectric constant of the entire measurement cross section. There were problems such as chipping, and the high possibility that the properties of the soil sample would change over time after being collected, making it difficult to obtain high measurement accuracy.

This invention was made to solve the above problems, and it is possible to accurately calculate the relative permittivity of the ground using an impedance/relative permittivity conversion table created in advance based on actual measured values. The purpose of this study is to obtain an underground dielectric constant measuring device that can be used.

[Means to solve the problem]

The underground dielectric constant measuring device according to the present invention includes an antenna that radiates electromagnetic waves from the ground surface toward the ground and receives reflected waves from the ground, and measures the impedance of the antenna and the ground. and an impedance measuring means to calculate the ratio corresponding to the measured impedance in the calculation means by referring to an impedance/relative permittivity conversion table prepared in advance based on the impedance of the antenna and the underground where the relative permittivity is known. The dielectric constant is determined by calculation.

[Effect]

The underground relative permittivity measurement device of the present invention compares the measured values of the impedance of an antenna installed on the ground surface and the underground with an impedance/relative permittivity conversion table prepared in advance.

By determining the relative permittivity corresponding to the above measured value as the relative permittivity of the above-mentioned underground where the antenna is installed, it is possible to quickly and accurately obtain the desired relative permittivity measurement data with a simple WM operation. , If necessary, the results can be used for high-precision exploration of underground objects.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

In Figure 1, 11 is the ground surface, 12 is the antenna, and 13
is an impedance measuring means connected to this antenna 12, and 14 is a calculation means.

Next, the operation will be explained.

First, the antenna 12 is installed on the ground surface at a location where the relative dielectric constant of the ground is known. Next, under the control of the calculation means 14,
Electromagnetic waves are radiated from the antenna 12 via the impedance measuring means 13, and the antenna 12 receives reflected waves from underground. Therefore, in accordance with this reception result, the impedance measuring means 13 measures the impedance of the antenna and the ground whose dielectric constant is known. Then, the calculation means 14 creates an impedance/specific vi electric constant conversion table in which the relative permittivity of the ground and the impedance measured above are used as corresponding data, and stores this in a memory or the like. In this way, a large number of impedances and their relative permittivity measured by placing the antenna 12 on the underground surface of which the relative permittivity is known are stored in the memory in the calculating means 14 as an impedance/relative permittivity conversion table. By doing so, it is possible to improve the relative dielectric constant calculation accuracy.

Next, an antenna 12 is placed on the ground surface at a place where the relative permittivity of the ground is unknown, and electromagnetic waves are radiated in the same manner as in Section J], and the reflected waves from underground are received by the antenna 12.

As a result, under the control of the calculating means 14, the impedance measuring means 3 measures the impedance between the antenna 12 and the ground whose relative permittivity is unknown, and inputs the value into the calculating means 14. The calculation means 14 calculates the measured relative index 1! By comparing and referring to the impedance of the underground where the relative permittivity is unknown and the impedance of the antenna 12 and the impedance/relative permittivity conversion table, the relative permittivity of the underground where the relative permittivity is unknown is calculated.

Figure 2 shows an application of this invention to the exploration of underground objects. In the figure, 21 is the ground surface, 22 is a transmitting antenna that emits electromagnetic waves underground, 23 is a receiving antenna that receives reflected waves from underground, and 24 is a transmitting antenna 2 that emits electromagnetic waves.
25 is a receiver that receives the received signal from the receiving antenna 25, 26 is a calculation means, 27 is an impedance measurement means, and 28 is an underground object as an exploration target.

Next, the operation will be explained.

First, using the calculating means 26, the impedance measuring means 27, and the receiving antenna 23 capable of transmitting and receiving electromagnetic waves, measure the underground impedance of which the relative permittivity U coefficient is known in the same manner as above, and calculate the impedance/relative permittivity. Create a conversion table and store it in memory. Next, at a buried object exploration site with an unknown dielectric constant, the receiving antenna 23 is installed on the ground surface 21, and the calculation means 26 is installed in the same manner as above.
Under the control of the impedance measuring means 27, electromagnetic waves are radiated underground through the receiving antenna 23. In addition, the reflected wave is received by the receiving antenna 23, and using this received data, the relative permittivity of the underground at the exploration site for buried objects with unknown relative permittivity is calculated using the above impedance/relative permittivity conversion table. Furthermore, under the control of the calculation means 26, an electromagnetic wave is applied from the transmitter 24 to the transmitting antenna 22, and the electromagnetic wave is radiated from the transmitting antenna 22 toward the ground. Now, if there is an underground object 28, the receiving antenna 23 receives a reflected wave that is an echo of the underground object 28, and the receiver 25 processes the received wave as a signal and sends it to the calculation means 26.
send to The calculating means 26 uses the relative dielectric constant of the buried object exploration site calculated above and the propagation velocity of electromagnetic waves resulting from this to calculate the position of the underground object 28 determined by the following formula % Formula % (4) r: Depth t of buried object: The echo reception time from the buried object is corrected, and the accurate position of the underground object 28 can be determined.

In the above embodiment, the impedance measuring means 27 is provided separately from the receiver 25, but the same function may be incorporated in the receiver 25, and the same effects as in the above embodiment can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, there is provided an antenna that radiates electromagnetic waves from the ground surface toward the ground and receives reflected waves from the ground, and an impedance that measures the impedance of the antenna and the ground. measuring means, and with reference to an impedance/relative permittivity conversion table prepared in advance based on the L antenna and the underground impedance with known relative permittivity, the calculation means calculates the relative permittivity corresponding to the impedance measured above. Since the ratio is calculated by calculation, there is no need to collect soil samples as in the past, and even when paved with asphalt or concrete, the relative permittivity of the ground can be easily measured from outside the paved surface. Furthermore, the relative dielectric constant of the ground can be calculated quickly and with high accuracy without considering changes in the properties of the soil as a sample over time.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an underground dielectric constant measuring device according to an embodiment of the present invention, FIG. 2 is a block diagram showing an application example of the underground dielectric constant measuring device according to the present invention, and FIG. The figure is a circuit diagram showing a conventional underground dielectric constant measuring device, and FIG. 4 is an explanatory diagram showing the vector relationship of voltages at various parts of the circuit shown in FIG. 3. 11 is the ground surface, ]-2 is the antenna, 13 is the impedance measurement means, and 14 is the calculation means. In the figures, the same reference numerals indicate the same or equivalent parts. Figure Figure

Claims (1)

[Claims] An antenna that radiates electromagnetic waves from the ground surface toward the ground and receives reflected waves from the ground, an impedance measuring means for measuring the impedance of the antenna and the ground, and a known dielectric constant of the antenna and the ground. The impedance created in advance based on the underground impedance of
An underground relative permittivity measuring device, comprising: calculation means for calculating a relative permittivity corresponding to the measured impedance with reference to a relative permittivity conversion table.