JP2000075026A - Method and device for estimating electromagnetic wave propagation velocity in underground propulsion method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately estimate distance to an underground buried object with a simple configuration. SOLUTION: A transmission means 18 and a reception means 21 for prospecting by radar are provided at an underground drill head, at the same time a magnetic field generation means 23 is provided, a magnetic field detection means 26 for detecting an electromagnetic wave being generated from the magnetic field generation means 23 and a second radar reception means 25 for detecting an electromagnetic wave being transmitted from the transmission means 18 for prospecting by radar are provided on the ground surface, an electromagnetic wave propagation velocity V is obtained from the relationship between the distance from the drill head to the ground surface based on a detection value by the magnetic field detection means 26 and arrival time by the second radar reception means 25, and the obtained velocity is integrated with reflection wave arrival time T3 of an underground buried object by the first radar reception means 21, thus obtaining distance L from the drill head to the underground buried object.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an underground structure such as an existing underground structure or an underground pipe when laying various pipelines using the so-called underground propulsion method. The present invention relates to a method and apparatus for estimating an electromagnetic wave propagation velocity, a method and apparatus for displaying an electromagnetic wave propagation distance, and a method and apparatus for underground exploration in an underground propulsion method that can be suitably implemented to detect a buried object.

[0002]

2. Description of the Related Art As a technique for estimating the propagation speed of an electromagnetic wave transmitted underground, a migration processing method for processing a survey image of a surface-scanning radar search device offline to estimate the propagation speed of the electromagnetic wave underground. Is well known. This is because underground burial is performed by changing the parameter of the underground propagation velocity so that the hyperbolic reflection signal obtained after passing just above the underground buried pipe is converged to one point. Obtains the underground propagation speed for the buried position of the object.

If the propagation speed of an electromagnetic wave in the ground can be estimated in this way, the propagation speed of the reflected signal from the transmitting antenna of the propulsion unit to the underground object is multiplied by the propagation time of the measured reflected signal. The distance is calculated based on the skill of the operator.

[0004]

In the above prior art,
In the underground propulsion method, the propagation speed of electromagnetic waves in the ground varies depending on the soil content of the soil, the water content that changes depending on the groundwater level and the presence or absence of seepage water from the ground surface. The problem is that the distance cannot be determined accurately. Also, in calculating the distance to the underground object before the propellant collides with the underground object, the product of the underground propagation speed and the propagation time obtained by the underground exploration device by the above-mentioned migration processing method is offline. Before the propulsion body collides with the underground object, the distance to the underground object is calculated in real time,
There is a problem that it is impossible to display the information, and it is impossible to recognize the underground object in advance in parallel with the propulsion operation of the propulsion body.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for estimating an electromagnetic wave propagation velocity in an underground propulsion method in which an electromagnetic wave propagation velocity in the ground can be accurately estimated in real time before the propulsion body reaches an underground object. And equipment.

Another object of the present invention is to provide an electromagnetic wave propagation distance in an underground propulsion method in which the electromagnetic wave propagation distance in the ground can be accurately displayed in real time before the propulsion body reaches an underground object. A display method and apparatus are provided.

Yet another object of the present invention is to enable the distance from a propulsion body to an underground object to be detected in real time accurately and with a simple configuration before the propulsion body reaches the underground object. It is an object of the present invention to provide an underground exploration method and apparatus in the underground propulsion method.

[0008]

According to the present invention, there is provided a radar transmitting means having a radar transmitting antenna for generating and transmitting an electromagnetic wave to a propulsion body propelled underground, and a radar transmitting means of the radar transmitting means. A first radar receiving unit having a radar receiving antenna for receiving a reflected wave reflected by an underground object transmitted from an antenna, and a magnetic field generating unit having a magnetic field generating element are mounted. A second radar receiving means having a receiving antenna for receiving an electromagnetic wave transmitted from the ground by the radar transmitting means on the surface directly above, and a strength of a magnetic field generated in the ground by the magnetic field generating means or a change thereof. Providing a magnetic field detecting means for detecting, in response to an output from the magnetic field detecting means, measuring a depth D from the ground surface to the tip of the propulsion body,
The electromagnetic wave transmitted from the transmitting antenna of the radar transmitting means is received by the receiving antenna of the second radar receiving means on the ground surface, the arrival time T1 is measured, the depth D / the arrival time T1 is calculated, and This is an electromagnetic wave propagation velocity estimating method in the underground propulsion method, wherein an electromagnetic wave propagation velocity V is obtained.

According to the present invention, a radar transmitting means, a first radar receiving means, and a magnetic field generating means are mounted on a propulsion body for propelling underground. A second radar receiving means and a magnetic field detecting means are provided on the ground surface directly above the tip of the propulsion body. In the ground, there are underground buried objects such as underground pipes or other underground structures that are conduits for transporting gas, water, etc., and the position of such underground buried objects is promoted. You need to anticipate before your body reaches you. For this purpose, first, the magnetic field from the magnetic field generating means mounted on the underground propulsion body is detected by the magnetic field detecting means on the ground, and the electromagnetic wave transmitted from the radar transmitting means under the ground is
Detected by radar receiving means.

The calculating means responds to the output from the magnetic field detecting means to determine the depth D from the ground surface to the tip of the propulsion body and the time until the electromagnetic wave from the radar transmitting means is received by the second radar receiving means on the ground. The arrival time T1 is measured. The arrival time T1 is obtained as a value between the maximum values (peak values) of the measured received signal waveforms, and can be automatically specified by detecting this value T1 by a predetermined algorithm. The depth D can also be detected automatically by the magnetic field detecting means, so to speak, by calculating the depth D / the arrival time T1 using the depth D and the arrival time T1, the propagation velocity V can be calculated. Can be accurately obtained in real time.

According to a second aspect of the present invention, there is provided a radar transmitting means having a radar transmitting antenna for generating and transmitting an electromagnetic wave to a propulsion body propelling underground, and a ground transmitted from the radar transmitting antenna of the radar transmitting means. First radar receiving means having a radar receiving antenna for receiving a reflected wave reflected by the embedded object, and magnetic field generating means having a magnetic field generating element are mounted, and the ground surface immediately above the tip of the propulsion body is Second radar receiving means having a receiving antenna for receiving electromagnetic waves transmitted by the radar transmitting means underground; magnetic field detecting means for detecting the intensity of a magnetic field generated by the magnetic field generating means or a change thereof; In response to the output from the magnetic field detecting means, the depth D from the ground surface to the tip of the propulsion body is measured, and transmitted from the transmitting antenna of the radar transmitting means. Its arrival time T of the electromagnetic wave received by the ground of the second radar receiving means of the receiving antenna
1 is calculated, the depth D / the arrival time T1 is calculated, and the propagation velocity V of the electromagnetic wave in the ground is obtained.
, The display of the electromagnetic wave propagation distance axis of the visual display means for displaying the information received and received by the first radar receiving means is changed.

According to the present invention, a radar transmitting means, a first radar receiving means, and a magnetic field generating means are mounted on a propulsion body for propelling underground. A second radar receiving means and a magnetic field detecting means are provided on the ground surface directly above the tip of the propulsion body. In the ground, there are underground buried objects such as underground pipes or other underground structures that are conduits for transporting gas, water, etc., and the position of such underground buried objects is promoted. You need to anticipate before your body reaches you. For this purpose, first, the magnetic field from the magnetic field generating means mounted on the underground propulsion body is detected by the magnetic field detecting means on the ground, and the electromagnetic wave transmitted from the radar transmitting means under the ground is
Detected by radar receiving means.

The calculating means is responsive to the output from the magnetic field detecting means to determine the depth D from the ground surface to the tip of the propulsion body and the time until the electromagnetic wave from the radar transmitting means is received by the second radar receiving means on the ground. The arrival time T1 is measured. The arrival time T1 is obtained as a value between the maximum values (peak values) of the measured received signal waveforms, and can be automatically specified by detecting this value T1 by a predetermined algorithm. The depth D can also be detected automatically by the magnetic field detecting means, so to speak, by calculating the depth D / the arrival time T1 using the depth D and the arrival time T1, the propagation velocity V can be calculated. Can be accurately obtained in real time.

The exploration image displayed by the visual display means takes the propulsion distance x and the arrival time T1 of the electromagnetic wave as input data, performs predetermined arithmetic processing, and calculates the axis X indicating the propulsion distance and the one-way propagation distance of the electromagnetic wave. It may be displayed as a graph with the indicated axis Y.

The electromagnetic wave propagation distance axis Y is changed based on the propagation velocity V as described above. For example, when the full scale of the arrival time T1 axis is 20 nsec, the electromagnetic wave propagation velocity becomes 0.50 ×
When it is calculated to be 10 ⁸ m / sec, the full scale of the displayed Y axis is 1 m. At each place of the propulsion process, the propagation speed V can be displayed more accurately by calculating and displaying the full scale displayed and updating, but for example, the length of the propulsion drill head is reduced. In the case of 3 m / line, the Y-axis full scale display may be updated every time the vehicle is propelled by 3 m.

According to a third aspect of the present invention, there is provided a radar transmitting means having a radar transmitting antenna for generating and transmitting an electromagnetic wave to a propulsion body propelling underground, and a ground transmitted from the radar transmitting antenna of the radar transmitting means. First radar receiving means having a radar receiving antenna for receiving a reflected wave reflected by the embedded object, and magnetic field generating means having a magnetic field generating element are mounted, and the ground surface immediately above the tip of the propulsion body is Second radar receiving means having a receiving antenna for receiving electromagnetic waves transmitted by the radar transmitting means underground; magnetic field detecting means for detecting the intensity of a magnetic field generated by the magnetic field generating means or a change thereof; In response to the output from the magnetic field detecting means, the depth D from the ground surface to the tip of the propulsion body is measured, and transmitted from the transmitting antenna of the radar transmitting means. Its arrival time T of the electromagnetic wave received by the ground of the second radar receiving means of the receiving antenna
1 is calculated, the depth D / the arrival time T1 is calculated, and the propagation velocity V of the electromagnetic wave in the ground is obtained. The electromagnetic wave transmitted from the radar transmitting means is reflected by the underground object and the first radar The time T2 until reception by the receiving means is measured, and the propagation speed V and 1/2 of the time T2 are measured.
And the product V · T3 of the time T3 is calculated to obtain the distance L from the radar transmitting antenna to the underground buried object.

According to the present invention, the time T2 from the time when the electromagnetic wave transmitted from the radar transmitting means is reflected by the underground object to the time when the electromagnetic wave is received by the first radar receiving means is measured, and １ ／ of this time T2 is measured. The product V · T3 of the time T3 and the propagation velocity V obtained as described above is calculated, and the distance L from the radar transmitting antenna of the propulsion body to the underground object is obtained. The arrival time T2 is automatically specified, so to speak, by detecting a maximum value (peak value) of a reflected signal having an amplitude equal to or more than a predetermined amplitude value within a time range to be measured by a predetermined algorithm. Alternatively, a commercially available computer software program such as Windows may be used to display the waveform in real time on its display screen, and the arrival time T may be calculated using a mouse.
The operator may specify a position considered to correspond to 2, for example, by clicking the position.

According to a fourth aspect of the present invention, there is provided a radar transmitting means having a radar transmitting antenna for generating and transmitting an electromagnetic wave to a propulsion body propelling underground, and a ground transmitted from the radar transmitting antenna of the radar transmitting means. First radar receiving means having a radar receiving antenna for receiving a reflected wave reflected by the embedded object, and magnetic field generating means having a magnetic field generating element are mounted, and the ground surface immediately above the tip of the propulsion body is Second radar receiving means having a receiving antenna for receiving electromagnetic waves transmitted by the radar transmitting means underground; magnetic field detecting means for detecting the intensity of a magnetic field generated by the magnetic field generating means or a change thereof; In response to the output from the magnetic field detecting means, the depth D from the ground surface to the tip of the propulsion body is measured, and transmitted from the transmitting antenna of the radar transmitting means. Its arrival time T of the electromagnetic wave received by the ground of the second radar receiving means of the receiving antenna
1. An electromagnetic wave propagation velocity estimating apparatus in an underground propulsion method, comprising: an arithmetic means for measuring the depth D / the arrival time T1 and calculating the propagation velocity V of the electromagnetic wave in the ground.

According to the present invention, the propulsion body for propelling underground is equipped with radar transmitting means, first radar receiving means, and magnetic field generating means. A second radar receiving means and a magnetic field detecting means are provided on the ground surface directly above the tip of the propulsion body. In the ground, there are underground buried objects such as underground pipes or other underground structures that are conduits for transporting gas, water, etc., and the position of such underground buried objects is promoted. You need to anticipate before your body reaches you. For this purpose, first, the magnetic field from the magnetic field generation means mounted on the underground propulsion body is detected by the ground magnetic field detection means, and the electromagnetic wave transmitted from the underground radar transmission means is transmitted to the first ground on the ground.
Detected by radar receiving means.

The calculating means responds to the output from the magnetic field detecting means to determine the depth D from the ground surface to the tip of the propulsion body and the time until the electromagnetic wave from the radar transmitting means is received by the second radar receiving means on the ground. The arrival time T1 is measured. The arrival time T1 is obtained as a value between the maximum values (peak values) of the measured received signal waveforms, and can be automatically specified by detecting this value T1 by a predetermined algorithm. The depth D can also be detected automatically by the magnetic field detecting means, so to speak, by calculating the depth D / the arrival time T1 using the depth D and the arrival time T1, the propagation velocity V can be calculated. Can be accurately obtained in real time.

According to a fifth aspect of the present invention, there is provided a radar transmitting means having a radar transmitting antenna for generating and transmitting an electromagnetic wave to a propulsion body propelling underground, and a ground transmitted from the radar transmitting antenna of the radar transmitting means. First radar receiving means having a radar receiving antenna for receiving a reflected wave reflected by the embedded object, and magnetic field generating means having a magnetic field generating element are mounted, and the ground surface immediately above the tip of the propulsion body is Second radar receiving means having a receiving antenna for receiving electromagnetic waves transmitted by the radar transmitting means underground; magnetic field detecting means for detecting the intensity of a magnetic field generated by the magnetic field generating means or a change thereof; In response to the output from the magnetic field detecting means, the depth D from the ground surface to the tip of the propulsion body is measured, and transmitted from the transmitting antenna of the radar transmitting means. Its arrival time T of the electromagnetic wave received by the ground of the second radar receiving means of the receiving antenna
1 to calculate the depth D / arrival time T1 to obtain the propagation velocity V of the electromagnetic wave in the ground, and the first radar receiving means based on the propagation velocity V to obtain the propagation velocity V. And a visual display means for displaying the obtained information by changing the display of the electromagnetic wave propagation distance axis. The electromagnetic wave propagation distance display device in the underground propulsion method.

According to the present invention, the propulsion body for propelling underground is equipped with radar transmitting means, first radar receiving means, and magnetic field generating means. A second radar receiving means and a magnetic field detecting means are provided on the ground surface directly above the tip of the propulsion body. In the ground, there are underground buried objects such as underground pipes or other underground structures that are conduits for transporting gas, water, etc., and the position of such underground buried objects is promoted. You need to anticipate before your body reaches you. For this purpose, first, the magnetic field from the magnetic field generation means mounted on the underground propulsion body is detected by the ground magnetic field detection means, and the electromagnetic wave transmitted from the underground radar transmission means is transmitted to the first ground on the ground.
Detected by radar receiving means.

The calculating means responds to the output from the magnetic field detecting means to determine the depth D from the ground surface to the tip of the propulsion body and the time until the electromagnetic wave from the radar transmitting means is received by the second radar receiving means on the ground. The arrival time T1 is measured. The arrival time T1 is obtained as a value between the maximum values (peak values) of the measured received signal waveforms, and can be automatically specified by detecting this value T1 by a predetermined algorithm. The depth D can also be detected automatically by the magnetic field detecting means, so to speak, by calculating the depth D / the arrival time T1 using the depth D and the arrival time T1, the propagation velocity V can be calculated. Can be accurately obtained in real time.

The search image displayed by the visual display means takes the propulsion distance x and the arrival time T1 of the electromagnetic wave as input data, performs predetermined arithmetic processing, and calculates the axis X indicating the propulsion distance and the one-way propagation distance of the electromagnetic wave. It may be displayed as a graph with the indicated axis Y.

The electromagnetic wave propagation distance axis Y is changed based on the propagation velocity V as described above. For example, when the full scale of the Y-axis is 20 nsec, the electromagnetic wave propagation velocity becomes 0.50 × 10 ⁸ m /
When it is calculated to be sec, the full scale of the displayed Y axis is 1 m. At each place of the propulsion process, the propagation speed V can be displayed more accurately by calculating and displaying the full scale displayed and updating, but for example, the length of the propulsion drill head is reduced. In the case of 3 m / line, the Y-axis full scale display may be updated every time the vehicle is propelled by 3 m.

According to a sixth aspect of the present invention, there is provided a radar transmitting means having a radar transmitting antenna for generating and transmitting an electromagnetic wave to a propulsion body propelled underground, and a ground transmitted from the radar transmitting antenna of the radar transmitting means. First radar receiving means having a radar receiving antenna for receiving a reflected wave reflected by the embedded object, and magnetic field generating means having a magnetic field generating element are mounted, and the ground surface immediately above the tip of the propulsion body is Second radar receiving means having a receiving antenna for receiving electromagnetic waves transmitted by the radar transmitting means underground; magnetic field detecting means for detecting the intensity of a magnetic field generated by the magnetic field generating means or a change thereof; In response to the output from the magnetic field detecting means, the depth D from the ground surface to the tip of the propulsion body is measured, and transmitted from the transmitting antenna of the radar transmitting means. Its arrival time T of the electromagnetic wave received by the ground of the second radar receiving means of the receiving antenna
1 to calculate the depth D / arrival time T1 to obtain the propagation velocity V of the electromagnetic wave in the ground, and the first radar receiving means based on the propagation velocity V to obtain the propagation velocity V. Visual display means for displaying the obtained information by changing the display of the electromagnetic wave propagation distance axis, wherein the calculating means is configured such that the distance L from the transmitting antenna of the radar transmitting means to the underground object is equal to or less than a predetermined value. It is characterized in that it is provided with an alarm means for judging whether or not there is, and when judging that the distance L is equal to or less than a predetermined value, outputs an alarm signal and generates an alarm in response to the alarm signal. This is an underground exploration device in the underground propulsion method.

According to the present invention, the propagation speed V of the electromagnetic wave from the tip of the underground propulsion body to the ground surface immediately above it and the arrival time T2 of the reflected wave by the buried underground object are obtained, and these propagation speeds V are obtained. The distance from the tip of the propulsion body to the underground object can be calculated and obtained based on the arrival time T2 of the reflected wave.

According to the arrival time T2 of the reflected wave, the electromagnetic wave transmitted from the transmitting antenna of the radar transmitting means mounted on the tip of the propulsion body is reflected on the underground object and mounted on the tip of the propulsion body. Since this is the round-trip time until reception by the receiving antenna of the first radar receiving means, this time T2
One-way arrival time T of the reflected wave obtained by × 1/2
3 multiplied by the propagation velocity V, the distance from the propulsion body to the underground object, more specifically, the distance L from the transmitting antenna incorporated in the propulsion body to the underground object.
Can be requested.

The propagation speed V and the time T2 obtained by such arithmetic means are determined by printing means such as a printer.
What is necessary is just to output and display using existing output means such as a visual display means such as a cathode ray tube or a liquid crystal display panel. Therefore, it is necessary to read out the propagation speed V and the time T2 output from the arithmetic means in a recognizable state. It is also possible to prepare in advance an output means capable of performing the above-mentioned operations, and electrically connect an arithmetic means to this output means to obtain the distance to the buried object.

The magnetic field detecting means may be provided with a coil for performing an electromagnetic induction magnetic search for detecting an AC magnetic field as a magnetic field detecting element, or realized by a semiconductor element such as a Hall element for detecting a DC magnetic field. Is also good. With such a magnetic field detecting element, it is possible to detect the strength of a magnetic field or a change thereof, that is, a DC magnetic field or an AC magnetic field due to an underground object, and further detect the direction of the strength of the magnetic field. Among the underground objects detected by such a radar-type exploration, it is possible to distinguish between the objects embedded by the magnetic field detection and the remaining objects. The magnetic field detection search includes an electromagnetic induction type search using an AC magnetic field and a search using a DC magnetic field. Further, the transmitting antenna provided in the radar transmitting means and the receiving antenna provided in the first radar receiving means have not only a configuration in which the transmitting antenna and the receiving antenna are realized by two separate antennas, but also a switching of a single antenna. A configuration that achieves each function of transmission and reception by, for example, electrically switching by means may be used.

In this way, the electromagnetic wave from the radar transmitting means of the radar transmitting means and the first radar receiving means necessary for the radar-based exploration for detecting the presence of an underground object is detected on the ground by the second radar receiving means. To measure the arrival time T1 from the tip of the propulsion body to the surface of the ground and the depth D by detecting the magnetic field from the underground magnetic field generating means by the magnetic field detecting means on the ground, V, and the distance from the tip of the propulsion body to the underground object can be obtained in real time based on the propagation speed V and the arrival time T2. It is possible to obtain the distance to the underground object.

In this way, the distance L from the transmitting antenna to the underground object is obtained by the calculating means. When the tip of the propulsion body approaches the vicinity of the underground object, the existence of the underground object is determined. Can be easily recognized. Therefore, the propulsion unit is propelled underground avoiding the underground objects, and the propulsion operation of the propulsion unit is determined in a short time without interruption for a long time to confirm the underground objects,
Alternatively, propulsion can be performed while determining the direction of propulsion, and conduits for efficiently transporting gas etc. can be laid, and it is ensured that the propulsion body contacts the underground object and damages the underground object Can be prevented.

If the distance L from the transmitting antenna to the underground object is equal to or less than a predetermined value, the calculating means outputs a warning signal, and the warning means generates a warning in response to the warning signal. As the alarm unit, an alarm sound may be generated when the alarm signal is input. For example, the alarm unit may be realized by an alarm sound generating unit such as a buzzer. For example, the alarm state can be visually displayed. For example, the alarm state may be realized by a visual display unit such as a plasma display, a cathode ray tube, and a liquid crystal display panel.

[0034] By such a warning means, the operator can be surely recognized that the propulsion unit has approached the underground object, and the propulsion unit must be propelled before contacting or colliding with the underground object. The change of the direction or the stop of the propulsion operation can be prompted to prevent damage to the underground object.
The predetermined value is appropriately determined according to the size of the underground object, the material of the underground object, the degree of flexibility of the flexible tube to be laid by the propulsion body, and the like. Further, as the predetermined value, not only one value but also a plurality of values may be selected. By setting a plurality of values as the predetermined value in this way, a warning means that the propulsion body approaches the underground object is displayed in multiple stages by the alarm means, and the propulsion body approaches the underground object. The degree can be immediately and easily recognized. Further, as a predetermined value, 1
Alternatively, a plurality of ranges may be set, and also in this case, the warning means may be configured to make the display form by sound or image different according to each range and be recognized by the operator.

[0035]

FIG. 1 is a block diagram showing an electric configuration of an underground exploration apparatus 2 provided in an underground propulsion facility 1 in an underground propulsion method according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing the overall schematic configuration of the underground propulsion equipment 1. In the underground propulsion equipment 1, a flexible propulsion body 5 propelled from the ground surface 3 into the soil 4, is pushed through the propulsion body 5 in the axial direction through the propulsion direction 6, and is propelled by the propulsion body 2. And a propulsion drive means 7 for angularly displacing the base end portion of the base member around the axis to rotate the base end portion. The propulsion body 5 includes a flexible propulsion body body 8 and a rigid drill head 10 detachably connected to the distal end 9 of the propulsion body body 8.

To propel the propulsion body 5 into the soil 4, the drill head 10 penetrates into the soil 4, and the propulsion pipe, which constitutes a part of the propulsion body 8, is the most upstream in the propulsion direction 6. Pressing into the soil 4 while sequentially adding, and proceeding with excavation. The propulsion unit 5 removes the drill head 10 on the reaching shaft or the ground surface 3 formed in the soil 4, connects the end of a thermoplastic synthetic resin pipe such as polyethylene to be laid, and then pulls back the propulsion unit 5. Then, the synthetic resin pipe is drawn into the starting shaft 11 or the ground surface 3 and the operation is completed.

The underground exploration apparatus 2 includes a transmitting antenna 1 for generating and transmitting electromagnetic waves to a propulsion body 5 for propelling in the soil 4.
A first radar receiving means 21 having a receiving antenna 20 for receiving a reflected wave transmitted from the transmitting antenna 17 of the radar transmitting means 18 and reflected by the underground object 19; A magnetic field generating means 23 having an element 22 is mounted, and a receiving antenna 24 for receiving an electromagnetic wave transmitted underground by the radar transmitting means 18 on the ground surface 3 immediately above the drill head 10 which is the tip of the propulsion body 5. Radar receiving means 25 having
And a magnetic field detecting means 26 having a magnetic field detecting element 32 for detecting the intensity of a magnetic field generated in the ground by the magnetic field generating means 23 or its change.

The underground exploration device 2 also measures the depth D from the ground surface 3 to the drill head 10 of the propulsion unit 5 in response to the output from the magnetic field detecting means 26, and An electromagnetic wave is transmitted from the transmitting antenna 17, and the electromagnetic wave is received by the receiving antenna 24 of the second radar receiving means 25 on the ground surface 3, the arrival time T1 is measured, and the depth D / the arrival time T1 is calculated. , The propagation speed V of the electromagnetic wave in the ground is obtained, and the electromagnetic wave is transmitted from the radar transmitting means 18 so that the electromagnetic wave is transmitted to the underground object 19.
Calculating means 27 for calculating a time T2 from the time when the light is reflected by the first radar receiving means 21 until the time T2 is received.

The calculating means 27 calculates the propagation speed V and 1/1 / T2 of the time from when the electromagnetic wave is transmitted from the radar transmitting means 18 to when the electromagnetic wave is received by the first radar receiving means 21.
By calculating the product V · T3 with the time T3 of 2, the distance L from the transmitting antenna 17 to the underground object 19 is obtained. The calculating means 27 also transmits the underground object 1 from the transmitting antenna 17.
9 is determined to be less than or equal to a predetermined value input and set by the input means 31, and the distance L
Is determined to be equal to or less than a predetermined value, an alarm signal is output, and in response to the alarm signal, an alarm is visually displayed on a display screen 29 of a visual display means 28 as an alarm means.

FIG. 3 is a sectional view of the vicinity of the drill head 10 of the propulsion body 5. The cross section perpendicular to the axis of the propulsion body 5 is a uniform circle along the axis, and the tip portion 35 of the drill head 10 is formed with a flat inclined surface 36, which is formed in a tapered shape. Is done. The inclined surface 36 is inclined in a direction intersecting with the axis 37 of the propulsion body 5 and thus of the drill head 10.

Since the inclined surface 36 is formed at the tip portion 35 of the drill head 10 as described above, at least the drill head 10 of the propulsion body 5 can be moved straight by being pushed around while rotating about the axis 37. it can. Also, at least the drill head 10 of the propulsion body 5 is
By pushing around without rotating around
The propulsion body main body 8 having flexibility can be curved and excavated in the soil 4. By bending the propulsion body 8 as described above, even if the underground object 19 exists in the soil 4, the propulsion body 5 can be propelled while avoiding the underground object 19. The inclined surface 36 is realized by an end plate 38 made of a dielectric material such as a flat synthetic resin.

In the tip portion 35 of the drill head 10,
A transmitting antenna 17 of the radar transmitting means 18 and a receiving antenna 20 of the first radar receiving means 21 are provided. The end plate 38 forms a front part of the transmitting antenna 17 and the receiving antenna 20. The inclined surface 36 has an angle α with respect to the axis 37.
And the angle α is selected in the range of 5 to 25 °, preferably 15 °. The transmitting antenna 17 and the receiving antenna 20 are realized by, for example, a bowtie antenna. In another embodiment of the present invention, the transmitting antenna 17 and the receiving antenna 20 may be used as a transmitting antenna and a receiving antenna by electrically switching one antenna by a switching circuit.

Referring again to FIG.
Generates electromagnetic waves, which are radio waves. Receiving antenna 20
Receives the electromagnetic wave. The electromagnetic waves from the transmitting antenna 17 and the receiving antenna 20 cause the underground object 19
And the search data thus obtained is received by the arithmetic means 27 on the ground, for example, via a cable 39 inserted into the propulsion body 5. The calculation means 27 includes a visual display means 28 for visually displaying whether or not the underground object 19 exists near the distal end portion 35. The visual display means 28 has a display screen 29 realized by, for example, a liquid crystal display device or a cathode ray tube. The output from the magnetic field detection means 26 is input to the calculation means 27 after being amplified by the amplification circuit 46 and subjected to signal processing by the processing circuit 47. The output of the second radar receiving means 25 is input after being subjected to signal processing by the processing circuit 47 by the amplification circuit 45.

The pulse generation circuit 41 serving as a pulser gives the transmission antenna 17 an impulse-like or rectangular-wave transmission signal in response to the drive signal from the drive circuit 42. The electromagnetic wave radiated by the transmitting antenna 17 is
Radiation in a direction perpendicular to Electromagnetic waves radiated from the transmitting antenna 17 are also reflected by the underground object 19 and reflected by the ground surface 3, and these reflected waves are received by the receiving antenna 20 and amplified by the amplifier circuit 43. The output of the amplification circuit 43 is
Given to.

The processing circuit 44 is realized by, for example, a microcomputer or the like, and responds to the output of the driving circuit 42 synchronized with the impulse or rectangular wave transmission signal from the pulse generation circuit 41 and the reception signal from the amplification circuit 43. Then, the received signal output through the amplifier circuit 43 of the receiving antenna 20 is sampled and further digitized,
The image signal of the underground buried object 19 and the signal of the reflected wave from the ground surface 3 are derived via the cable 39, and the calculation means 27
Is further processed, and is visually displayed on the display screen 29 of the visual display means 28.

FIG. 4 is a sectional view showing a state where the propulsion unit 5 is propelling underground. The magnetic field generating means 23 called a sonde is housed in the drill head 10. On the ground surface 3, the magnetic field detecting means 26 is provided. The drill head 10 is made of a ferromagnetic material. As this ferromagnetic material, for example, stainless steel is used. In the drill head 10, a plurality of slits 49 (six in total in every 60 degrees in the circumferential direction in this embodiment) extending in the direction of the axis 37 at equal intervals in the circumferential direction are formed. Drill head 1 for soil, water, etc.
In order to prevent intrusion into the inside of the housing, for example, a synthetic resin made of a non-magnetic material is embedded and closed.

In the present embodiment, a detection coil is used as the magnetic field detecting element 32 for detecting the magnetic field of the magnetic field detecting means 26. In another embodiment of the present invention, a semiconductor element may be used as the magnetic field generating element 32.

FIG. 5A shows a waveform of a transmission signal transmitted from the transmitting antenna 17 of the radar transmitting means 18, and FIG. 5B shows a receiving antenna 24 of the second radar receiving means 25.
1 shows a waveform of a reception signal received by the STA. Transmission signal p
The time difference W1 from the time t1 when the signal 1 is generated to the time t2 when the received signal p2 is obtained is determined by the transmission and reception antennas 1
7 and 20 and the distance to the underground object 19 from which the electromagnetic wave is reflected. Therefore, the distance L between the tip portion 35 of the drill head 10 and the underground object 19 can be assumed by the time difference W1, but the distance L between the tip portion 35 of the drill head 10 and the underground object 19 can be estimated. The effect of the moisture content, which varies depending on the soil quality of the soil 4 and the groundwater level and the presence or absence of seepage water from the ground surface 3,
This affects the time difference W1 from the transmission time t1 of the electromagnetic wave from the transmission antenna 17 to the time t2 received by the reception antenna 20, and thus the detection accuracy of the distance L from the tip portion 35 of the drill head 10 to the underground object 19. May not always be sufficient.

Therefore, in this embodiment, the electromagnetic wave transmitted from the transmitting antenna 17 of the underground radar transmitting means 18 is transmitted to the receiving antenna 24 of the second radar receiving means 25 on the ground.
And the arrival time T1 is measured, and the magnetic field emitted from the magnetic field generating element 22 of the magnetic field generating means 23 is detected by the magnetic field detecting means 26 on the ground, and the magnetic field emitted from above the ground vertically above the drill head 10, ie, The depth D from the surface is measured.

Based on the arrival time T1 and the depth D, the calculating means 27 calculates the depth D / the arrival time T1, and calculates the propagation speed V of the electromagnetic wave in the soil 4 between the drill head 10 and the ground surface 3. Ask for. Next, the product of the above propagation velocity V and the time T2 obtained in the ground is calculated, and the tip portion 35 of the drill head 10 is connected to the transmitting antenna 17 and the receiving antenna 20 and the underground object 19 in more detail. The distance L between them is determined.

In this manner, the distance L between the tip portion 35 of the drill head 10 and the underground object 19 is always obtained based on the propagation speed V of the soil 4 at the propulsion position by the drill head 10. An error caused by a difference in propagation speed due to an influence of a water content or the like can be remarkably reduced, and the distance L to the underground object 19 can be obtained with high accuracy in real time.

The distance L calculated by the calculation means 27 is derived by the visual display means 28,
For example, a numerical value is displayed on the display screen 29. When the distance L is equal to or less than a predetermined value, for example, 30 cm or less, the arithmetic unit 27 outputs an alarm signal to the visual display unit 28 and causes the display screen to display an alarm on the display screen 29, for example, a blinking display. Alternatively, a buzzer (not shown) may be intermittently sounded to make the operator recognize that the drill head 10 has approached the underground object 19 beyond the allowable range.

FIG. 6 is a diagram showing an example of a display state on the display screen 29. In the figure, the horizontal axis indicates the propulsion distance of the propulsion body 5, and the vertical axis indicates the reflection time of the electromagnetic wave. The horizontal axis (propulsion distance) of the display screen 29 is 200 pixels, and the vertical axis (reflection time) is 250 pixels. Regarding the propulsion distance, the actual travel distance, that is, the drill head 10
Since the reflected signal is not received on the downstream side of the current position in the propulsion direction, the reflected signal intensity is set to 0 and two-dimensional image data is generated. In addition, the reflection time actually represents the sampling time of the propagation time of the electromagnetic wave whose electromagnetic wave reflection time is 0 nsec reciprocating in the underground object 19, and the reflection time is measured from 0 nsec to 20 nsec. 256 quantizations of the received reflected signal at the sampling point of the reflection time are performed for each x.

The intensity of the reflected signal quantized by the predetermined number of bits is displayed on the display screen 29 of the visual display means 28 at an intensity of 0 at an intermediate luminance, and is displayed at a high luminance when the polarity of the signal intensity is positive. , When the value is negative, the image is displayed with low brightness. The number of gradations of display luminance is determined by the number of quantization bits. FIG.
Shows an example of a display state on the display screen 29, and reference numeral 51 shows a reflected wave signal image by the buried pipe.

FIG. 7 is a diagram showing conditions of an experiment by the present inventor for confirming a difference in the propagation speed of electromagnetic waves in the ground. Earth and sand 55 interposed between the transmitter 53 and the receiver 54
Has a relative dielectric constant of 13, and the frequency of the electromagnetic wave transmitted from the transmitter 53 is 1 GHz. Further, the interval ΔL1 between the transmitter 53 and the receiver 54 is 30 cm, and the waveform of the signal received by the receiver 54 at this time is indicated by reference numeral p3 in FIG. 8A.

The waveform of the signal received by the receiver 54 when the distance ΔL2 between the transmitter 53 and the receiver 54 is set to 50 cm is indicated by reference numeral p4 in FIG. 8 (2). The time differences W3 and W4 from the transmission start time W0 to the peaks of these waveforms p3 and p4 are 5.16 nsec and 8.
61 nsec, and the electromagnetic wave propagation velocity V at this time is:
In each case, it was confirmed that V = 0.58 × 10 ⁸ m / sec. It has been confirmed that when the interval between the transmitter 53 and the receiver 54 increases, the amplitudes of the reception signals p3 and p4 also decrease.

The present inventor conducted further experiments and found that
In soils with a relatively low water level, the propagation speed of electromagnetic waves in the soil is almost the same, and it is not necessary to adjust the distance to the underground buried objects.However, moisture in the soil near rivers, lakes and marshes, and the sea, etc. In many places, the ground surface 3 and the drill head 10
Since the propagation velocity V has a distribution in the depth direction between the two, the distance to the underground buried object obtained by using the propagation velocity is reduced by at most 20% so that the underground burying can be performed with higher accuracy. It has been confirmed that the distance to the object can be obtained.

Where the soil quality of soil 4 can be clearly seen,
The correction value (Δn%) of the propagation velocity V to the underground buried object obtained as described above may be changed empirically or experimentally, and may be changed. Then, a process of reducing the propagation velocity V to the underground object obtained as described above by about Δn = 20% may be performed. This allows for underground objects, such as 50c, to be distant
Since the underground object existing about m in front is converted as being about 40 cm ahead, it is possible to at least avoid the problem that the underground object 19 is damaged by the drill head 10 during propulsion. Further, the correction value of the distance L to the underground object determined by the propagation speed V and the arrival time T3 may be determined in advance by using the relative dielectric constant obtained by a soil test or the like.

As another embodiment of the present invention, the correction values based on the soil quality and groundwater are stored in a memory (not shown) of the calculating means 27, and the distance to the underground object is visually displayed as a corrected converted value. 28 may be displayed on the display screen 29.

[0060]

According to the present invention, the depth D from the ground surface to the tip of the propulsion body in response to the output from the magnetic field detecting means, and the electromagnetic wave from the radar transmitting means. Is measured until arrival time is received by the second radar receiver on the ground, and the depth D and the arrival time T1 are calculated using the depth D and the arrival time T1, so that the propagation speed V is calculated. Can be accurately obtained in real time.

According to the second and fifth aspects of the present invention, since the electromagnetic wave propagation distance axis displayed by the visual display means is changed based on the propagation speed V, each of the propulsion processes is performed. In the place, the display can be performed more accurately by calculating and displaying the full scale displayed by calculating the propagation speed V.

According to the third aspect of the present invention, the propagation speed V of the electromagnetic wave from the tip of the underground propulsion body to the ground surface immediately above it and the arrival time T2 of the reflected wave by the underground buried object are obtained. The propagation velocity V and the arrival time T2 of the reflected wave
, The distance from the tip of the propulsion body to the underground object can be calculated and obtained.

The arrival time T2 of the reflected wave is determined by the fact that the electromagnetic wave transmitted from the transmitting antenna of the radar transmitting means mounted on the tip of the propulsion body is reflected on the underground object and mounted on the tip of the propulsion body. Since this is the round-trip time until reception by the receiving antenna of the first radar receiving means, this time T2
One-way arrival time T of the reflected wave obtained by × 1/2
3 multiplied by the propagation velocity V, the distance from the propulsion body to the underground object, more specifically, the distance L from the transmitting antenna incorporated in the propulsion body to the underground object.
Can be requested.

The propagation speed V and the time T2 obtained by such arithmetic means are determined by printing means such as a printer,
What is necessary is just to output and display using existing output means such as a visual display means such as a cathode ray tube or a liquid crystal display panel. Therefore, it is necessary to read out the propagation speed V and the time T2 output from the arithmetic means in a recognizable state. It is also possible to prepare in advance an output means capable of performing the above-mentioned operations, and electrically connect an arithmetic means to this output means to obtain the distance to the buried object.

The magnetic field detecting means may be provided with a coil for performing an electromagnetic induction magnetic search for detecting an AC magnetic field as a magnetic field detecting element, or realized by a semiconductor element such as a Hall element for detecting a DC magnetic field. Is also good. With such a magnetic field detecting element, it is possible to detect the strength of a magnetic field or a change thereof, that is, a DC magnetic field or an AC magnetic field due to an underground object, and further detect the direction of the strength of the magnetic field. Among the underground objects detected by such a radar-type exploration, it is possible to distinguish between the objects embedded by the magnetic field detection and the remaining objects. The magnetic field detection search includes an electromagnetic induction type search using an AC magnetic field and a search using a DC magnetic field. Further, the transmitting antenna provided in the radar transmitting means and the receiving antenna provided in the first radar receiving means have not only a configuration in which the transmitting antenna and the receiving antenna are realized by two separate antennas, but also a switching of a single antenna. A configuration that achieves each function of transmission and reception by, for example, electrically switching by means may be used.

As described above, the electromagnetic wave from the radar transmitting means of the radar transmitting means and the first radar receiving means necessary for the radar-based exploration for detecting the presence of an underground object is detected on the ground by the second radar receiving means. To measure the arrival time T1 from the tip of the propulsion body to the surface of the ground, and detect the magnetic field from the underground magnetic field generating means by the magnetic field detecting means on the ground to measure the depth D, and measure the electromagnetic wave propagation velocity under the ground. V, and the distance from the tip of the propulsion body to the underground object can be obtained in real time based on the propagation speed V and the arrival time T2. It is possible to obtain the distance to the underground object.

In this way, the distance L from the transmitting antenna to the underground object is obtained by the calculating means. When the tip of the propulsion body approaches the vicinity of the underground object, the existence of the underground object is determined. Can be easily recognized. Therefore, the propulsion unit is propelled underground avoiding the underground objects, and the propulsion operation of the propulsion unit is determined in a short time without interruption for a long time to confirm the underground objects,
Alternatively, propulsion can be performed while determining the direction of propulsion, and conduits for efficiently transporting gas etc. can be laid, and it is ensured that the propulsion body contacts the underground object and damages the underground object Can be prevented.

According to the present invention, if the distance L from the transmitting antenna to the underground object is equal to or less than a predetermined value, the arithmetic means outputs an alarm signal, and the alarm means outputs the alarm signal. Generates an alarm in response to As the alarm unit, an alarm sound may be generated when the alarm signal is input. For example, the alarm unit may be realized by an alarm sound generating unit such as a buzzer. An alarm condition can be visually displayed by, for example, a plasma display,
It may be realized by visual display means such as a cathode ray tube and a liquid crystal display panel.

By such an alarm means, the operator can be surely recognized that the propulsion body has approached the underground object, and the propulsion body must be propelled before contacting or colliding with the underground object. The change of the direction or the stop of the propulsion operation can be prompted to prevent damage to the underground object.
The predetermined value is appropriately determined according to the size of the underground object, the material of the underground object, the degree of flexibility of the flexible tube to be laid by the propulsion body, and the like. Further, as the predetermined value, not only one value but also a plurality of values may be selected. By setting a plurality of values as the predetermined value in this way, a warning means that the propulsion body approaches the underground object is displayed in multiple stages by the alarm means, and the propulsion body approaches the underground object. The degree can be immediately and easily recognized. Further, as a predetermined value, 1
Alternatively, a plurality of ranges may be set, and also in this case, the warning means may be configured to make the display form by sound or image different according to each range and be recognized by the operator.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical configuration of an underground exploration device 2 provided in an underground propulsion facility 1 in an underground propulsion method according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a schematic configuration of the entire underground propulsion facility 1.

FIG. 3 is a cross-sectional view of the vicinity of a drill head 10 of the propulsion body 5.

FIG. 4 is a cross-sectional view showing a state where the propulsion body 5 is propelling underground.

FIG. 5A shows a waveform of a transmission signal transmitted from the transmission antenna 17 of the radar transmission means 18;
(2) shows the waveform of the received signal received by the receiving antenna 24 of the second radar receiving means 25.

6 is a diagram showing an example of a display state on a display screen 29. FIG.

FIG. 7 is a diagram showing experimental conditions for confirming a difference in electromagnetic wave propagation velocity in the figure by the present inventor.

8A shows a waveform of a reception signal p3 from the receiver 54 when an interval ΔL1 between the transmitter 53 and the receiver 54 is set to 30 cm, and FIG. 7 shows a waveform of a reception signal p4 by the receiver 54 when an interval ΔL2 between the receivers 54 is set to 50 cm.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Underground propulsion equipment 2 Underground exploration device 3 Ground surface 4 Soil 5 Propulsion body 6 Propulsion direction 8 Propulsion body 10 Drill head 17 Transmitting antenna 18 Radar transmitting means 19 Underground buried object 20 Receiving antenna 21 First radar receiving means 22 Magnetic field generating element 23 Magnetic field generating means 24 Receiving antenna 25 Second radar receiving means 26 Magnetic field detecting means 27 Computing means 28 Visual display means 29 Display screen

Claims (6)

[Claims] 1. A radar transmitting means having a radar transmitting antenna for generating and transmitting an electromagnetic wave to a propulsion body propelled underground, and reflected by an underground object transmitted from the radar transmitting antenna of the radar transmitting means. A first radar receiving means having a radar receiving antenna for receiving a reflected wave, and a magnetic field generating means having a magnetic field generating element are mounted. A second radar receiving unit having a receiving antenna for receiving the transmitted electromagnetic wave; and a magnetic field detecting unit for detecting a strength of a magnetic field generated in the ground by the magnetic field generating unit or a change in the magnetic field. In response to the output of the radar, the depth D from the ground surface to the tip of the propulsion body is measured, and the electromagnetic wave transmitted from the transmitting antenna of the radar transmitting means is measured on the ground surface. (2) Underground propulsion which receives by a receiving antenna of two radar receiving means, measures its arrival time T1, calculates the depth D / arrival time T1, and finds the propagation velocity V of electromagnetic waves in the ground. Method of estimating electromagnetic wave propagation velocity in the construction method. 2. A radar transmitting means having a radar transmitting antenna for generating and transmitting an electromagnetic wave to a propulsion body propelled underground, and reflected by an underground object transmitted from the radar transmitting antenna of the radar transmitting means. A first radar receiving means having a radar receiving antenna for receiving a reflected wave, and a magnetic field generating means having a magnetic field generating element are mounted. A second radar receiving unit having a receiving antenna for receiving the transmitted electromagnetic wave; and a magnetic field detecting unit for detecting a strength of a magnetic field generated in the ground by the magnetic field generating unit or a change in the magnetic field. In response to the output of the radar, the depth D from the ground surface to the tip of the propulsion body is measured, and the electromagnetic wave transmitted from the transmitting antenna of the radar transmitting means is measured on the ground surface. 2 The reception time T1 is received by the receiving antenna of the radar receiving means, the arrival time T1 is measured, the depth D / the arrival time T1 is calculated, and the propagation velocity V of the electromagnetic wave in the ground is obtained. 2. The method according to claim 1, wherein the display of the electromagnetic wave propagation distance axis of the visual display means for displaying the information received and received by the first radar receiving means is changed. . 3. A radar transmitting means having a radar transmitting antenna for generating and transmitting an electromagnetic wave to a propulsion body propelling underground, and reflected by an underground object transmitted from the radar transmitting antenna of the radar transmitting means. A first radar receiving means having a radar receiving antenna for receiving a reflected wave, and a magnetic field generating means having a magnetic field generating element are mounted. A second radar receiving unit having a receiving antenna for receiving the transmitted electromagnetic wave; and a magnetic field detecting unit for detecting a strength of a magnetic field generated in the ground by the magnetic field generating unit or a change in the magnetic field. In response to the output of the radar, the depth D from the ground surface to the tip of the propulsion body is measured, and the electromagnetic wave transmitted from the transmitting antenna of the radar transmitting means is measured on the ground surface. 2 Received by the receiving antenna of the radar receiving means and measures its arrival time T1, calculates the depth D / the arrival time T1, and finds the propagation velocity V of the electromagnetic wave in the ground, which is transmitted from the radar transmitting means. A time T2 from when the electromagnetic wave is reflected by the underground object to when it is received by the first radar receiving means is measured, and a product V · T3 of the propagation velocity V and a time T3 that is a half of the time T2 is obtained. And calculating the distance L from the radar transmitting antenna to the underground buried object in the underground propulsion method. 4. A radar transmitting means having a radar transmitting antenna for generating and transmitting an electromagnetic wave to a propulsion body propelling underground, and reflected by an underground object transmitted from the radar transmitting antenna of the radar transmitting means. A first radar receiving means having a radar receiving antenna for receiving a reflected wave, and a magnetic field generating means having a magnetic field generating element are mounted. A second radar receiving unit having a receiving antenna for receiving the transmitted electromagnetic wave; and a magnetic field detecting unit for detecting a strength of a magnetic field generated in the ground by the magnetic field generating unit or a change in the magnetic field. In response to the output of the radar, the depth D from the ground surface to the tip of the propulsion body is measured, and the electromagnetic wave transmitted from the transmitting antenna of the radar transmitting means is measured on the ground surface. The radar device further comprises a calculating means for receiving the data by the receiving antenna of the radar receiving means, measuring the arrival time T1, calculating the depth D / the reaching time T1, and calculating the propagation velocity V of the electromagnetic wave in the ground. For estimating the propagation speed of electromagnetic waves in the underground propulsion method. 5. A radar transmitting means having a radar transmitting antenna for generating and transmitting an electromagnetic wave to a propulsion body propelled underground, and reflected by an underground object transmitted from the radar transmitting antenna of the radar transmitting means. A first radar receiving means having a radar receiving antenna for receiving a reflected wave, and a magnetic field generating means having a magnetic field generating element are mounted. A second radar receiving unit having a receiving antenna for receiving the transmitted electromagnetic wave; and a magnetic field detecting unit for detecting a strength of a magnetic field generated in the ground by the magnetic field generating unit or a change in the magnetic field. In response to the output of the radar, the depth D from the ground surface to the tip of the propulsion body is measured, and the electromagnetic wave transmitted from the transmitting antenna of the radar transmitting means is measured on the ground surface. 2 a receiving means of the radar receiving means for measuring the arrival time T1 and calculating the depth D / the arrival time T1 to calculate the propagation velocity V of the electromagnetic wave in the ground; And a visual display means for displaying information obtained by the first radar receiving means by changing the display of the electromagnetic wave propagation distance axis based on the electromagnetic wave propagation distance in the underground propulsion method. Display device. 6. A radar transmitting means having a radar transmitting antenna for generating and transmitting an electromagnetic wave to a propulsion body propelled underground, and reflected by an underground object transmitted from the radar transmitting antenna of the radar transmitting means. A first radar receiving means having a radar receiving antenna for receiving a reflected wave, and a magnetic field generating means having a magnetic field generating element are mounted. A second radar receiving unit having a receiving antenna for receiving the transmitted electromagnetic wave; and a magnetic field detecting unit for detecting a strength of a magnetic field generated in the ground by the magnetic field generating unit or a change in the magnetic field. In response to the output of the radar, the depth D from the ground surface to the tip of the propulsion body is measured, and the electromagnetic wave transmitted from the transmitting antenna of the radar transmitting means is measured on the ground surface. 2 a receiving means of the radar receiving means for measuring the arrival time T1 and calculating the depth D / the arrival time T1 to calculate the propagation velocity V of the electromagnetic wave in the ground; And visual display means for displaying information obtained by the first radar receiving means while changing the display of the electromagnetic wave propagation distance axis, based on It is determined whether or not the distance L to the underground buried object is equal to or less than a predetermined value, and when it is determined that the distance L is equal to or less than the predetermined value, an alarm signal is output, and in response to the alarm signal, An underground exploration device in an underground propulsion method, wherein an alarm means for generating an alarm is provided.