JPH11280382A - Probing device and method in underground pipe jacking method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect an underground buried article existing in front of a pipe jacking body accurately. SOLUTION: Transmitting and receiving antennas 16a, 16b are installed into a tapered front end section 9 with an inclined plane 10 in the drill head 5 of a pipe jacking body 2 propelling in soil 1, and a dielectric 15 consisting of a material having thickness increased towards the downstream side in the propulsive direction and having a dielectric constant higher than the dielectric constant of soil is arranged to the front section of these antennas. Electromagnetic waves from the transmitting antenna 16a are radiated into soil 1 in approximately parallel with the axis 11 of the drill head 5, and the reflected waves of an underground buried article 14 are received by the receiving antenna 16b or (16c).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method of laying various pipelines underground using a so-called underground propulsion method.
An apparatus and method for detecting and exploring an existing underground object while preventing damage to the existing underground object.

[0002]

2. Description of the Related Art In a proposed underground propulsion method, a drill head of a propulsion body for propelling in soil is provided with a tapered tip having a flat inclined surface inclined with respect to the axis of the propulsion body. Then, the propulsion body is pushed in the propulsion direction at the base end thereof, is propelled, and is angularly displaced about the axis, so that the propulsion direction can be changed to be straight or curved. In the drill head, a transmitting and receiving antenna is provided facing the inclined surface, and an electromagnetic wave is generated to receive a reflected wave from the underground object, whereby the underground object can be detected. Therefore, the propulsion body can be propelled underground while avoiding underground objects.

[0003] In this proposed technique, the direction of the electromagnetic wave of the antenna is perpendicular to the inclined surface. Therefore, for example, the intensity of the electromagnetic wave radiated toward the underground object located downstream on the axis of the drill head in the propulsion direction (that is, forward in the propulsion direction) is small, and the intensity of the reflected wave is small.
Therefore, there is a problem that it is difficult to detect an underground object in the forward direction of the propulsion.

In order to solve this problem, it is easy to increase the directivity of the antenna. However, with such a configuration, the position of the underground object is located on or near the axis of the drill head. It will not be possible to detect if it is present or if it is located relatively far away from the axis of the drill head.

In another proposed technique, a transmitter, which is a sonde for generating electromagnetic waves, is provided in a drill head of a propulsion body for propelling in soil, and a coil for receiving electromagnetic waves from the transmitter on a ground surface is provided. To receive the electromagnetic waves from the transmitter. Thereby, the position of the drill head for propelling underground can be detected. Even with this proposed technique, it is difficult to accurately locate the underground object, as in the above-mentioned technique.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an underground propulsion method and apparatus in which the position of an underground object can be accurately detected.

[0007]

According to the present invention, a drill head of a propulsion body for propelling in the soil is provided with a tapered tip having a flat inclined surface inclined with respect to the axis of the propulsion body. The body is pushed in the axial direction on the upstream side in the propulsion direction from the drill head, and at least the propulsion drive means for angularly displacing the drill head around the axis, and the electromagnetic wave is generated and reflected in the distal end portion facing the inclined surface. A transmitting and receiving antenna for receiving a wave is provided, and the transmitting and receiving antenna is provided with a transmitting signal and driven, and a means for processing a received signal of a reflected wave is provided. An exploration device in an underground propulsion method characterized in that a dielectric whose thickness changes in a propulsion direction is provided at a front portion, and an electromagnetic wave is refracted by the dielectric.

According to the present invention, a transmitting and receiving antenna is provided at the tip of the propulsion body. The transmitting and receiving antennas may be configured such that the transmitting antenna and the receiving antenna are individually configured, or a single antenna may be switched and connected by switching means for transmitting and receiving. In this specification,
"Transmit and receive antennas" or "transmit and receive antennas" refer not only to configurations in which two separate antennas are used, but also to transmit and receive such a single antenna by switching means. Must be interpreted as a concept including a configuration that achieves each of the functions described above.

An electromagnetic wave is generated from the transmitting antenna in the ground. The receiving antenna receives the reflected wave from the underground object in the soil, so that the underground object existing near the tip of the propulsion body can be detected.

An underground object is a conduit for transporting gas and water buried underground, or other underground structure.

According to the present invention, even when the propulsion body approaches the vicinity of an underground buried object, the presence of the underground buried object can be easily detected even when the propulsion body approaches the vicinity of the underground buried object even if the depth from the ground surface is large. Can be. In addition, the location of an underground object such as an underground structure can be known. Therefore, avoid the underground object and propel the propulsion body into the ground, thereby preventing the propulsion body from hitting or contacting the underground structure, which is an underground object, and damaging the obstacle. Can be prevented.

Further, according to the present invention, a dielectric constituting a front portion of the antenna is disposed at a tapered tip portion having an inclined surface of the drill head, and an electromagnetic wave from the antenna body of the transmitting and receiving antennas is The wave refracted by the dielectric and radiated into the soil, and the reflected wave from the underground object is refracted by the dielectric and received by the antenna.

[0013] Further, the present invention is characterized in that the dielectric has a thickness that increases toward the downstream side in the propulsion direction, and is made of a material having a relative permittivity exceeding the relative permittivity of the soil to be propelled.

According to the present invention, as clearly shown in FIG. 3 to be described later, the thickness of the dielectric is made larger as it goes forward, which is the downstream side in the propulsion direction. The relative permittivity ε1 is selected to be a value exceeding the relative permittivity ε2 of the soil to be propelled (ε1> ε2). This allows the electromagnetic waves generated by the antenna to radiate at an angle close to the axis of the drill head, for example substantially in the direction of propulsion. Therefore, the underground object existing in the drill head propulsion direction 6 can be accurately detected.

Further, the present invention is characterized in that the dielectric has a thickness that becomes smaller toward the downstream side in the propulsion direction, and is made of a material having a relative permittivity exceeding the relative permittivity of the soil to be propelled.

According to the present invention, as clearly shown in FIG. 6 to be described later, the thickness of the dielectric material is formed so as to become smaller toward the forward side which is the downstream side in the propulsion direction, and the ratio of the dielectric material is reduced. The dielectric constant ε1 is determined by the relative dielectric constant ε of the soil to be propelled.
2 (ε1> ε2). The electromagnetic waves generated by the antenna can thereby be emitted into the soil at a large angle with the axis of the drill head, for example, almost vertically. Therefore, the depth and position of the tip of the drill head from the ground surface can be accurately detected.

According to the present invention, there is further provided a propulsion body for propelling in soil, and a drill head of the propulsion body has a tapered tip having a flat inclined surface inclined with respect to the axis of the propulsion body. A transmission antenna that generates an electromagnetic wave is provided in the front end portion facing the inclined surface, and the front end portion has a thickness that becomes smaller toward the downstream in the propulsion direction at the front of the transmission antenna, and A dielectric made of a material having a relative permittivity exceeding the relative permittivity of the soil to be propelled is provided, and the propellant is pushed in the axial direction upstream of the drill head in the propulsion direction, and at least the drill head is turned around the axis. Displaces and drives by giving a transmission signal to the transmission antenna,
This is an exploration method in the underground propulsion method characterized by moving a receiving antenna on the ground surface, receiving an electromagnetic wave from the transmitting antenna, and detecting a position where the maximum intensity of the received electromagnetic wave is obtained.

According to the present invention, a transmitting antenna is provided facing the inclined surface of the tip of the drill head. The transmitting antenna has a thickness which becomes smaller toward the downstream side in the propulsion direction and has a lower soil ratio. By arranging a dielectric material having a relative permittivity exceeding the permittivity, electromagnetic waves generated from the transmitting antenna can be radiated into the soil at a large angle with respect to the axis of the drill head, for example, substantially perpendicularly. Therefore, the ground receiving antenna receives the electromagnetic wave of the transmitting antenna through the soil, and accurately determines the depth of the tip of the drill head from the ground surface, which depends on the maximum intensity of the electromagnetic wave obtained from the receiving antenna on the ground surface. Can be detected. It can be detected that the transmitting antenna, that is, the tip of the drill head is present immediately below the position on the ground surface where the maximum intensity of the electromagnetic wave received by the receiving antenna is obtained.

[0019]

FIG. 1 is a sectional view showing an underground propulsion method according to an embodiment of the present invention. A propelling body 2 having flexibility in the soil 1 is propelled from the ground surface 3 into the soil 1. The propulsion unit 2 includes a flexible propulsion unit body 4 and a drill head 5 connected to the propulsion unit body 4. The propulsion drive means 46 pushes the propulsion body 2 upstream of the drill head 5 in the propulsion direction, at the base end in this embodiment, in the axial direction of the propulsion body 2 as indicated by the propulsion direction 6,
Further, the base end of the propulsion body 2 can be rotationally driven by angular displacement about the axis.

When the propelling body 2 is propelled into the soil 1, the drill head 5 penetrates into the soil 1 and the propelling body 4
Is press-fitted into the soil 1 while sequentially adding propulsion pipes constituting a part of, and excavation is advanced. The propulsion unit 2 removes the drill head 5 at the reaching shaft 7 formed on the soil 1 or on the ground surface 3, connects the end of the polyethylene pipe to be laid, pulls back the propulsion unit 2, and starts the starting shaft 8. Or pull the polyethylene pipe to the ground and finish the work.

FIG. 2 is a sectional view showing the vicinity of the drill head 5 of the propulsion body 2. The cross section perpendicular to the axis of the propulsion body 2 is circular, and a flat inclined surface 10 is formed at the tip 9 of the drill head 5. The tip 9 is formed in a tapered shape. The inclined surface 10 is inclined with respect to the axis 11 of the propulsion body 2 and thus of the drill head 5. A jet hole 12 is formed at the tip end portion 9 of the drill head 5 so as to face the inclined surface 10 downstream in the propulsion direction 6 (to the left in FIG. 2). Through the flexible tube inserted into the propelling body 2,
Bentonite water is pressure-fed and injected from the supply source 13. The bentonite water facilitates the excavation of the soil 1 by the drill head 5 and stabilizes the wall of the formed excavation hole.

Since the inclined surface 10 is formed at the tip portion 9 of the drill head 5 as described above, the propulsion body 2 can be moved straight by pushing at least the drill head 5 while rotating and driving it. By pushing at least the drill head 5 without rotating it, the flexible propulsion body main body 4 can be bent and the soil 1 can be dug. By bending the propulsion body 4, even when the underground object 14 exists in the soil 1, the propulsion body 2 can be propelled while avoiding the underground object 14.

The inclined surface 10 at the tip 9 of the drill head 5 is made of a flat dielectric 15. In the distal end portion 9, a transmitting antenna 16a and a receiving antenna 16b are provided facing the dielectric 15, that is, the inclined surface 10.
In some cases, the suffixes a and b of the reference mark are omitted, and the numbers are collectively indicated only by numbers. In FIG. 2, the dielectric 15 forms the inclined surface 10.

The antenna 16 is realized by, for example, a bowtie antenna. These antennas 16
It is connected to an electric circuit 17 in the drill head 5. The electric circuit 17 is connected to another electric circuit provided on the ground surface 3.

FIG. 3 is an enlarged sectional view near the dielectric 15. The dielectric 15 is a triangular prism in this embodiment, and has a right triangle in the plane of FIGS. 2 and 3 perpendicular to the axis thereof. An antenna main body 53 of the transmission antenna 16a and an antenna main body 54 of the reception antenna 16b are arranged on the oblique side 32 of the dielectric 15. In this figure, the antennas 16a and 16b may be arranged parallel to the paper surface or may be arranged vertically. These antennas 16
The directivity directions of the electromagnetic waves of the antenna bodies 53 and 54 a and 16 b are perpendicular to the surface 32. Slope 10 of dielectric 15
And another plane 33 are at right angles. In this way, the dielectric 15 has a thickness that increases as it goes downstream in the propulsion direction (leftward in FIG. 3, that is, forward). Dielectric 1
5 constitutes a front part of the antennas 16a and 16b. The antennas 16a and 16b are composed of the dielectric body 15 and the antenna body 5
3, 54.

The relative permittivity ε1 of the dielectric 15 is selected to be greater than the relative permittivity ε2 of the soil 1 to be propelled (ε1> ε
2). The material having a dielectric constant of 15, for example, may be ceramics.

Let V1 be the speed of the electromagnetic wave in the dielectric 15,
Assuming that the velocity of the electromagnetic wave in the soil 1 is V2 and the incident angle θ1 and the emission angle θ2 formed with the normal 34 of the inclined surface 10 of the dielectric body 15 in contact with the soil 1, the following equation 1 is established.

V2 / V1 = √ε1 / √ε2 = sin θ2 / sin θ1 (1) For example, the relative permittivity ε1 = 90 of the dielectric 15, the relative permittivity ε2 = 40 of the soil 1, and the incident angle θ1 = 10 °. At this time, the emission angle θ2 = about 15 °. In a plate-like configuration in which the thickness of the dielectric 15 is constant, θ2 = about 8 °. According to the configuration of the present invention, the angle θ0 formed by the inclined surface 10 and the axis 11 when the flat dielectric is used is approximately 23 ° (= 8 °).
(+ 15 °), the electromagnetic wave can be refracted equivalently. Thus, according to the present invention, the traveling direction 35 of the main electromagnetic wave from the transmitting antenna 16a is at an angle close to the propulsion direction 6, and the received signal strength of the reflected wave from the underground buried object 14 ahead can be increased. it can.
Therefore, the underground object 14 existing in front of the propulsion direction 6
Can be detected accurately.

FIG. 4 is a block diagram showing a configuration of the electric circuit 17 shown in FIG. The transmission antenna 16a generates an electromagnetic wave that is a radio wave. Receiving antenna 16b receives the electromagnetic wave. The underground object 14 can be detected by the electromagnetic waves from the antenna 16, and the search data thus obtained is received by the output means 19, for example, on the ground via a cable 18 inserted into the propulsion body 2. The output means 19 includes an underground object 14 near the tip 9.
Is visually displayed as to whether or not is present. The output unit 19 may be a display unit realized by, for example, a liquid crystal or a cathode ray tube, or may be a unit that displays a numerical value or the like.

As an example of the electric circuit 17, for example, a sampler type underground radar may be used. The pulse generation circuit 20 is provided on the antenna main body 53 of the transmitting antenna 16a.
A pulse transmission signal is given by the driving means 21. The electromagnetic wave from the transmitting antenna 16a is radiated toward the soil 1. The electromagnetic wave from the transmitting antenna 16a is reflected by the underground object 14 or reflected by the ground surface 3, the reflected wave is received by the receiving antenna 16b, and the output of the antenna body 54 is amplified by the amplifier circuit 22. . The processing circuit 23 is realized by, for example, a microcomputer or the like, and responds to an output synchronized with a pulse-like transmission signal from the pulse generation circuit 20 and a reception signal from the amplification circuit 22. The image signal of the underground object 14 and the signal of the reflected wave from the ground surface 3 are derived via the cable 18 and displayed by the output means 19 as described above. Electric circuit 17 may also have other configurations.

The transmitting antenna 16a and the receiving antenna 16b
Although a different configuration may be used as shown in FIGS. 2 to 4, a single antenna may be switched and used in another embodiment of the present invention.

The angle θ0 between the inclined surface 10 and the axis 11 is
For example, it may be 8 ° or 15 °, 5-25 °
May be selected in the range. The pulse-like transmission waveform provided by the driving unit 21 from the pulse generation circuit 20 to the transmission antenna 16 may have a frequency range of, for example, 0.5 to 1.5 GHz.

FIG. 5 shows a state in which the soil 1 is being propelled using the propulsion body 2. As shown in FIG. 5 (1), the inclined surface 10 faces the ground surface 3 of the soil 1, or as shown in FIG. The underground object 14 in the forward direction of the propulsion direction 6 even in a state where the underground object 14 is directed downward on the opposite side to the ground surface 3.
Can be detected accurately.

FIG. 6 is a partial sectional view of another embodiment of the present invention. This embodiment is similar to the embodiment described with reference to FIGS. 1 to 5 described above, and corresponding parts are denoted by the same reference numerals. It should be noted that, in this embodiment, the configuration related to the dielectric 15a is indicated by the corresponding reference numeral with a suffix a. The dielectric 15a has a triangular prism shape similarly to the above-described embodiment, and is located on the downstream side in the propulsion direction 6 (FIG. 6).
To the left of the front). The relative permittivity ε1 of the dielectric 15a is made of a material that exceeds the relative permittivity ε2 of the soil 1 (ε1> ε2). Such materials include, for example, PVC (polyvinyl chloride), glass fiber reinforced plastic (FRP), and other synthetic resin materials such as ultra polyethylene (U.
PE). Dielectric 15a and antenna bodies 53a, 5
4a, the transmitting antenna 16a and the receiving antenna 16
b.

According to this embodiment, the transmitting antenna 1
The traveling direction 36 of the main electromagnetic wave from 6a is almost perpendicular to the propulsion direction 6, and the intensity of the received signal of the reflected wave returned from the boundary surface with the ground surface 3 increases. As a result, the time of the electromagnetic wave propagating to the ground surface 3 can be detected with high accuracy, and therefore, the depth that is the distance of the tip 9 of the drill head 5 to the ground surface 3 can be accurately detected.

FIG. 7A shows an experimental result obtained while the antenna is propelled with the inclined surface 10 of the antenna substantially parallel to the ground surface.

Using an exploration apparatus having the configuration shown in FIG. 6 described above and the other configuration being the same as that of the above-described embodiment, the inclined surface 10 is grounded as shown in FIG. According to an experiment performed by the inventor of the present invention, it is considered that an image equivalent to the image shown in FIG. The depth L1, which is the distance between the ground surface 3 and the axis 11 of the drill head 5, is the direct wave image 25 in the image obtained in FIG.
, And the time difference W1 between the reflected image 26 and the ground surface 3.

When at least the drill head 5 of the propulsion body 2 is angularly displaced around the axis 11, the state of FIG.
The rotated state is shown in FIG. 5 (2). The inclined surface 10 is downward. The image obtained by the output unit 19 at this time is as shown in FIG. 7 (2). When the underground buried object 14 does not exist, the underground buried object 14
And an image of the ground surface 3 of the soil 1 cannot be obtained.

7 (1) and 7 (2), for example, the X axis which is the horizontal axis indicates time, and the vertical Y axis indicates the direction along the propulsion direction 6 of the ground surface 3, for example. The depth L1 is expressed by Expression 2 using the time difference W1 and the relative permittivity ε1 of the soil 1.

L1 = W1 · c / √ε1 (2) where c is the propagation speed of the electromagnetic wave and is 3 × 10 ⁸ c
m. According to the experimental results of the present inventor, it has been confirmed that the distance L1 can be detected with relatively high accuracy.

As shown in FIG. 5, the axis 1 of the propulsion body 2
When at least the drill head 5 is angularly displaced around its axis 11 in a state where 1 is horizontal and parallel to the ground surface 3, the level of the received signal of the reflected wave by the receiving antenna 16b shown in FIG. The level changes from the large level in FIG. 7A to the zero level in FIG. 7B. Therefore, the rotation angle of the drill head 5 around the axis 11 can be detected by level discriminating the ratio of the level of the received signal from which the reflected image 26 is obtained to the maximum value of the received signal. The output means 19 includes means for calculating the ratio of the levels of the received signals and discriminating the level.

FIG. 8 is a partial sectional view of still another embodiment of the present invention. This embodiment is similar to the above-described embodiment, and corresponding portions are denoted by the same reference numerals.
It should be noted that, in this embodiment, the dielectric 15 described with reference to FIGS. 1 to 5 and the dielectric 15a described with reference to FIGS. 9 are arranged so as to form inclined surfaces 10 and 10a in one common plane. This makes it possible to obtain a direction 35 of the electromagnetic wave substantially parallel to the propulsion direction 6 and a direction 36 of the electromagnetic wave perpendicular to the propulsion direction 6. Each dielectric 15,
The above-described electric circuit 17 of FIG. 4 is provided for each 15a.

According to the embodiment shown in FIG. 8, it is possible to accurately detect the underground object 14 and the like in front of the drill head 5 in the propulsion direction 6, and to accurately determine the depth to the ground surface 3. By detecting, the position of the tip 9 of the drill head 5 can be accurately detected.

In still another embodiment of the present invention, only the transmitting antenna 16a is provided in association with the dielectric 15 or 15a, and the receiving antenna 16b is provided as indicated by the reference numeral 16c in FIG. It may be provided movably on the ground surface 3.

The receiving antenna 16c on the ground surface 3 may be moved by the operator 27 by hand, or may be moved by a cart or the like. This receiving antenna 1
The signal from 6c may be supplied to the amplifier circuit 22 in the electric circuit 17 of FIG. 4 in the same manner as the above-described receiving antenna 16b, and the arithmetic processing may be performed in the same manner. The reception antenna 16c receives the transmission signal to the transmission antenna 16a from the reception signal from the reception antenna 16c.
The time difference until the reception signal of c is obtained depends on the depth W1
It corresponds to. The position on the ground surface 3 where the maximum level of the received signal obtained by the receiving antenna 16c is obtained is:
The shortest distance to the transmitting antenna 16a in the soil 1,
Thus, it can be determined that the drill head 5 exists immediately below the receiving antenna 16c. Further, the ratio of the receiving intensity of the receiving antenna 16c to the maximum intensity is calculated by the calculating means,
The rotation angle of the inclined surface 10 around the axis 11 can be detected.

[0046]

According to the first aspect of the present invention, the transmitting and receiving antennas are provided at the tapered tip of the propulsion body having the inclined surface of the drill head, and the transmitting and receiving antennas are provided at the front of the antenna in the propulsion direction. Since the electromagnetic wave is refracted by arranging a dielectric material whose thickness changes along the direction, the directivity of the antenna can be narrowed, and the electromagnetic wave can be generated and received in a desired direction. This makes it possible to accurately detect the underground object, and also to accurately detect the depth of the tip of the drill head from the ground surface.

According to the second aspect of the present invention, at the front of the transmitting antenna provided at the tip of the drill head of the propulsion body,
Since a dielectric whose thickness changes along the propulsion direction is arranged to refract electromagnetic waves from the transmitting antenna, the directivity of the transmitting antenna is narrowed, and the direction is almost perpendicular to the axis of the drill head, for example. By generating electromagnetic waves in the direction and receiving electromagnetic waves with a receiving antenna movably provided on the ground surface, it is possible to accurately detect underground objects, and from the ground surface at the tip of the drill head Can be accurately detected.

Further, according to the present invention, the transmitting antenna is provided facing the inclined surface of the tip of the drill head, and the transmitting antenna generates an electromagnetic wave and the receiving antenna receives the electromagnetic wave on the ground surface. Compared with the path of the electromagnetic wave propagating back and forth in the soil according to the above-mentioned claim 1, the structure of the claim 2 is about １ ／ and the propagation path is only one-way, so that it is generated from the transmitting antenna. The amount of attenuation until the received electromagnetic wave is received by the receiving antenna on the ground surface is reduced by about half. Therefore, the tip of the drill head can be accurately detected. Further, since the electromagnetic wave propagation distance from the transmitting antenna to the receiving antenna becomes longer, even if the tip of the drill head is deep in the soil, the position can be detected.

According to the third aspect of the present invention, since a part of the inclined surface is formed by the dielectric itself, the structure can be simplified and the direction of the electromagnetic wave can be set accurately. Will be able to do it.

According to the fourth aspect of the present invention, as shown in FIG. 3, the thickness of the dielectric is increased toward the downstream side in the propulsion direction, and the relative permittivity of the dielectric is increased. By selecting a value that exceeds the relative permittivity of the soil, the electromagnetic wave is refracted forward in the downstream direction in the propulsion direction and emitted into the soil, so that underground objects can be accurately detected during propulsion. As a result, the propulsion body can be propelled while avoiding the underground object.

According to the fifth aspect of the present invention, as clearly shown in FIG. 6, the thickness of the dielectric material is formed so as to become smaller toward the forward side, which is the downstream side in the propulsion direction. By choosing the relative permittivity to be greater than the relative permittivity of the soil, the direction of the electromagnetic waves can be refracted to the axis of the drill head, for example, almost perpendicularly, thereby burying the underground existing on the side of the drill head. The object can be accurately detected, and the depth of the tip of the drill head from the ground surface can be accurately detected.

According to the sixth aspect of the present invention, the electromagnetic wave is provided by providing a dielectric whose thickness changes along the propulsion direction at the front of the transmitting and receiving antennas provided at the tip of the drill head having the inclined surface. Can be refracted, for example, almost parallel or almost perpendicular to the axis of the drill head, so that underground objects can be detected accurately and electromagnetic waves can be radiated almost perpendicular to the axis of the drill head. As a result, the depth of the tip of the drill head from the ground surface can be accurately detected.

According to the seventh aspect of the present invention, the front portion of the transmitting antenna provided at the tip end portion having the inclined surface of the drill head has a thickness which becomes smaller toward the downstream side in the propulsion direction and has a lower soil ratio. By providing a dielectric having a dielectric constant lower than that, the electromagnetic wave from the transmitting antenna can be radiated into the soil, for example, almost perpendicularly to the axis of the drill head, so that the electromagnetic wave is received using the receiving antenna at the ground surface. This makes it possible to accurately detect the depth corresponding to the time required for the electromagnetic wave from the transmitting antenna to be received by the receiving antenna, and to determine the position of the drill head where the maximum intensity of the electromagnetic wave received by the receiving antenna is obtained. The position can be detected accurately as if it were directly above the tip.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an underground propulsion method according to an embodiment of the present invention.

FIG. 2 is a sectional view of the vicinity of a drill head 5 of the propulsion body 2.

FIG. 3 is an enlarged sectional view near a dielectric 15;

FIG. 4 is a block diagram showing a configuration of an electric circuit 17 shown in FIG.

FIG. 5 shows a state in which the soil 1 is being propelled using the propulsion body 2.

FIG. 6 is a cross-sectional view of the vicinity of a part of a dielectric 15 according to another embodiment of the present invention.

FIG. 7 is a diagram showing a cross-sectional image of the soil 1 showing the results of experiments performed by the present inventor.

FIG. 8 is a partial cross-sectional view of still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Soil 2 Propulsion body 3 Ground surface 4 Propulsion body main body 5 Drill head 6 Propulsion direction 7 Attainment shaft 8 Start shaft 9 Tip part 10 Inclined surface 11 Axis 12 Injection hole 13 Supply source 14 Underground object 15, 15a Dielectric 16a Transmission Antenna 16b, 16c Receiving antenna 17 Electric circuit 19 Output means 20 Pulse generation circuit 21 Driving means 22 Amplifying circuit 23 Processing circuit 46 Propulsion driving means 53, 54 Antenna body

Claims (7)

[Claims] 1. A drill head of a propelling body for propelling in soil has a tapered tip having a flat inclined surface inclined with respect to the axis of the propelling body, and the propelling body is propelled more than the drill head. A propulsion drive unit that pushes the drill head in the axial direction on the upstream side and angularly displaces at least the drill head around the axis; and a transmission and reception antenna that generates an electromagnetic wave and receives a reflected wave while facing the inclined surface in the tip portion. Means for giving a transmission signal to the transmission and reception antennas and driving them, and processing the reception signal of the reflected wave. The front end portion includes a front portion of the transmission and reception antennas, which extends along the propulsion direction. An underground propulsion method, comprising: providing a dielectric material having a thickness that varies by refraction; and refracting an electromagnetic wave by the dielectric material. 2. A drill head of a propulsion body for propelling in soil has a tapered tip having a flat inclined surface inclined with respect to the axis of the propulsion body, and the propulsion body is driven more than the drill head. Driving means for pushing the drill head in the axial direction on the upstream side and angularly displacing at least the drill head around the axis, a transmitting antenna for generating electromagnetic waves facing the inclined surface in the tip end, and a transmitting signal to the transmitting antenna. A driving antenna, a receiving antenna for receiving a reflected wave of electromagnetic waves, and a means for arithmetically processing a reception signal from the receiving antenna. An underground propulsion method, comprising: providing a dielectric material having a thickness that varies along the surface thereof, and refracting an electromagnetic wave by the dielectric material. 3. The underground propulsion method according to claim 1, wherein a dielectric forms a part of the inclined surface. 4. The dielectric body according to claim 1, wherein the dielectric body has a thickness that increases toward the downstream side in the propulsion direction, and is made of a material having a relative permittivity exceeding the relative permittivity of the soil to be propelled. The exploration device in the underground propulsion method according to one of the above. 5. The dielectric body according to claim 1, wherein the dielectric body has a thickness that becomes smaller toward the downstream side in the propulsion direction, and is made of a material having a relative dielectric constant exceeding the relative dielectric constant of the soil to be propelled. The exploration device in the underground propulsion method according to one of the above. 6. A propulsion body for propelling in soil is prepared, and a drill head of the propulsion body is formed with a tapered tip having a flat inclined surface inclined with respect to the axis of the propulsion body. A transmitting and receiving antenna for generating an electromagnetic wave and receiving a reflected wave is provided in the front end portion facing the inclined surface, and the front end portion of the front end of the transmitting and receiving antenna has a thickness that changes along a propulsion direction. A dielectric is provided, the electromagnetic wave is refracted by this dielectric, and the propulsion body is pushed in the axial direction on the upstream side in the propulsion direction from the drill head, and at least the drill head is angularly displaced around the axis, and the transmission and reception antennas are provided. It is characterized by detecting the depth of the buried object or the tip of the drill head from the ground surface by applying the transmission signal and driving, and calculating the reception signal of the reflected wave. Exploration method in the mid-jacking method. 7. A propelling body for propelling in the soil is prepared, and a drill head of the propelling body is formed with a tapered tip having a flat inclined surface inclined with respect to the axis of the propelling body. A transmitting antenna for generating an electromagnetic wave is provided in the front end portion so as to face the inclined surface, and the front end portion of the front end portion of the transmitting antenna has a thickness that becomes smaller toward the downstream side in the propulsion direction, and is a soil to be propelled. A dielectric made of a material having a relative permittivity exceeding the relative permittivity of is provided, and the propulsion body is pushed in the axial direction upstream of the drill head in the propulsion direction, and at least the drill head is angularly displaced around the axis, To transmit a transmitting signal to the transmitting antenna, drive it, move the receiving antenna over the ground surface, receive the electromagnetic wave from the transmitting antenna, and detect the position where the maximum intensity of the received electromagnetic wave is obtained. Exploration method in underground jacking method to symptoms.