JP3255771B2 - Underground radar equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an underground radar apparatus for detecting an excavation obstacle in front of a cutter head of an excavator for excavating underground.

[0002]

2. Description of the Related Art Generally, when digging a tunnel underground in an urban area, it is necessary to dig under a building, and since there is a lot of traffic, traffic congestion is caused even under a road, so it is difficult to perform open pit mining. In many cases, a construction called a shield method in which the remaining soil excavated by the cutter head is discharged through a tunnel excavated by the cutter head is performed.

[0003] In this case, there is no problem if the soil to be excavated is clay-based or close to the clay-based one. The excavated teeth on the head will be damaged.

[0004] If the cutter head is damaged, it will help that it is not open pit mining, and it will be difficult to perform the recovery work, so it will take a long time to recover the work. Therefore, a radar antenna is attached to the cutter head, radio waves are emitted from it to detect the state of the underground, and whether there is any obstacle to excavation ahead is searched, and if an obstacle is found, Workers go out in front of the cutter head to remove the obstacles and take measures to prevent damage to the excavated teeth.

[0005]

However, since the conventional underground radar can only use a high frequency of, for example, about 300 MHz due to its structure, the attenuation of radio waves is large and it is not possible to detect a state in front of the cutter head by more than about 2 meters. By the way, the current excavator excavation speed is 10 per day.
Because it is about meters, even if it turns out that there is an obstacle, it is necessary to arrange for a husband, for example, to remove the obstacle from that point in time, but that arrangement requires at least about one day However, it is not possible to arrange for a husband or the like within the day. For this reason, construction stops on that day, and wasteful time occurs in which nothing can be done.

In order to eliminate such wasted time, it is only necessary to find out that there is an obstacle about the day before, and for this purpose, it is only necessary to search up to a state about 10 meters ahead. In order to perform such an exploration to the front, a radio wave having a low frequency may be used.

However, in order to radiate such radio waves, the shape of the antenna becomes large. The antenna will be damaged if it is pressed directly against the digging surface, so it is mounted embedded in the cutter head. When using a large shaped antenna when performing such mounting, the strength of the cutter head will be weakened this time, so it is not possible to use a too large antenna, and eventually the frequency of the radio wave used can not be too low. As a result, there was a limit to the distance that could be searched.

The present invention has been made in view of such a situation, and is capable of detecting an obstacle at least about one day before.

[0009]

In order to solve such a problem, a first aspect of the present invention is a first invention in which a first portion of a cutter head excavation surface is provided.
A first transmitting antenna and a second transmitting antenna provided near one peripheral portion and the other peripheral portion on the diameter of the antenna, and a 180 ° hybrid for supplying signals of opposite phases to the first transmitting antenna and the second transmitting antenna And a transmission circuit for supplying a high-frequency signal in a frequency band including a high-frequency signal having a half-wavelength of the cutter head as a half-wave frequency as a center frequency to the 180 ° hybrid circuit.

[0010] A second aspect of the present invention is the first and second aspects of the first aspect, wherein the first and second excavation surfaces are provided near one peripheral edge and near the other peripheral edge on a diameter orthogonal to a diameter at which the transmitting antenna is mounted. 2 transmitting antennas, and a 180 ° hybrid circuit that combines signals detected by the first receiving antenna and the second receiving antenna in opposite phases.

[0011]

When the first transmitting antenna and the second transmitting antenna are driven in opposite phases by a signal in a frequency band including a signal having a half wavelength of the diameter of the cutter head, a standing wave is generated in the cutter head. This standing wave has a frequency at which the diameter of the cutter head is approximately half a wavelength, and a radio wave of that frequency is transmitted, so that a result equivalent to using a low-frequency radio wave is obtained.

[0012]

FIG. 1 (a) is a view showing an antenna mounted state applied to the present invention, in which transmitting antennas 2 and 3 and receiving antennas 4 and 5 are mounted on a front portion of a cutter head 1. FIG. The transmitting antenna 2 is mounted near the diameter and near one peripheral edge of the cutter head 1, and the transmitting antenna 3 is mounted near the other peripheral edge of the diameter.

The receiving antennas 4 and 5 are mounted near the diameter orthogonal to the diameter at which the transmitting antenna is mounted and, similarly to the transmitting antennas 2 and 3, near one and other peripheral edges of the cutter head 1. Since the cutter head 1 performs excavation by pressing against the ground, if these antennas are directly attached to the front surface of the cutter head 1, the antenna may be damaged by the pressure.
For this reason, as shown in FIG. 1 (b), a hole is provided in the front surface of the cutter head, and an antenna is mounted in the hole so that the pressure when the cutter head 1 is pressed against the ground is not directly applied to the antenna. I have.

FIG. 2 shows a connection state between the 180 ° hybrid circuit and the antenna. The transmitting circuit 11 is connected to the transmitting antennas 2 and 3 via the 180 ° hybrid circuit 7. The 180 ° hybrid circuit 7 is the transmitting circuit 1
1 is output as a signal having a 180 ° phase difference, that is, a signal having an opposite phase. Therefore, the transmission antennas 2 and 3 are supplied with signals of opposite phases.

The transmission circuit 11 does not include the resonance frequencies of the transmission antennas 2 and 3, and generates a signal in a frequency band centered on a frequency having a half wavelength of the diameter of the cutter head 1. The signals received by the receiving antennas 4 and 5 are 18
The signal is synthesized as an opposite-phase signal by the 0 ° hybrid circuit 6 and supplied to the receiving circuit 12.

FIG. 4 is a block diagram showing the entire system. The transmission circuit 11 and the reception circuit 13 are controlled by a radar controller 12, and the transmission signal and the reception signal are transmitted to the 180 ° hybrid circuits 6 and 7 via the rotary joint 8. Sent and received between The cutter head moving distance pulses and is supplied from each device (not shown) to the radar controller 12 is supplied with the pulse signal of the rotary encoder or <br/> et al, so that the overall control is performed by the signal processing computer 14 It has become.

A signal processing computer 14 is connected to a data recording device 15 to record collected data, and is also connected to a color printer 16 and a CRT display 17 so that the detection status can be printed and displayed. Has become.

In the device configured as described above, the signal transmitted from the transmission circuit 11 is
The transmission antenna 2 via the 180 ° hybrid circuit 7,
3 is supplied. As a result, the transmission antennas 2 and 3 are 18
Driven by signals with different 0 ° phase.

The transmission circuit 11 does not include the resonance frequency of the transmission antennas 2 and 3 but includes a signal in a frequency band near the center which has a half-wavelength of the diameter of the cutter head 1, in this example, a frequency band of about 10 to 100 MHz. This signal is radiated from the transmitting antennas 2 and 3.

Incidentally, the transmitting antennas 2 and 3 have a shape sufficiently smaller than the diameter of the cutter head 1, so that the strength of the cutter head is not reduced by attaching the transmitting antennas 2 and 3. Therefore, the resonance frequency of the transmission antennas 2 and 3 as a single unit is
The frequency is sufficiently higher than the frequency that makes the diameter of the laser beam a half wavelength, in this example, about 300 MHZ.

For this reason, the transmitting antennas 2 and 3 do not directly resonate at a frequency of about 10 MHz to about 100 MHz when driven. Even if the transmitting antennas 2 and 3 themselves do not resonate at a natural frequency, signal components in a frequency band of about 10 MHz to 100 MHz are radiated.

The frequency to be driven is set to 10 around the frequency at which the diameter of the cutter head 1 is about half a wavelength.
From MHz to about 100MHz is distributed, and since the transmission antenna 2 and 3 are excited in antiphase, metal cutter head 1 resonates to the frequency of its diameter and half wavelength, figure cutterhead 1 A standing wave as shown in FIG. This frequency is a frequency of about 30 MHz indicated by the frequency f1 in FIG. 3 in this example.

Since other frequencies do not resonate with the cutter head 1, a resonated frequency component of about 30 MHz is radiated most strongly. This is reflected and received forward. The reflected signal also resonates with the cutter head 1, and the signals detected by the receiving antennas 4 and 5 are 1
Since the signals are synthesized in opposite phases by the 80 ° hybrid circuit 6, the far-field gain has the largest component of the frequency f1 as shown in FIG.

As described above, this frequency is a resonance frequency of the transmitting / receiving antenna, which is about 30 MHz which is sufficiently lower than about 300 MHz in this example. For this reason, the attenuation is much smaller than the frequency used conventionally, and it is possible to detect a distant one. In this example, it could be detected as far as about 10 meters.

As mentioned above, current excavators operate at 10
If an obstacle about 10 meters away can be found the previous day, it will be possible to prepare for removing the obstacle by the next day, for example, to prepare a husband. Therefore, even if the excavation work is stopped during the obstacle removal work, the excavation stop time is much shorter than the conventional one, and the excavation does not have to be stopped at least on the day when the obstacle is found, and the dead time is reduced. As a result, construction delays can be reduced as compared with conventional ones.

In the above description, the frequency band of the signal transmitted from the transmission circuit 11 is set to about 10 MHz to 100 MHz. However, depending on the configuration of the transmission circuit 11, the frequency transmitted therefrom may be higher, for example, the transmission antenna 2, There is also a possibility of including up to 3 natural resonance frequencies f2. In this case, since the transmitting antennas 2 and 3 resonate at a natural frequency in addition to the far field due to the signal resonating the cutter head 1, a near field is generated near the cutter head 1 as shown in FIG.

In this case, a near-field signal is also received as shown in FIG. Moreover, since the reception intensity of the near-field signal is generally higher than that of the far-field signal, detection of a distant obstacle is hindered. In such a case, a low-pass filter (LP) having characteristics as indicated by a chain line in FIG.
If F) is inserted between the transmission circuit 11 and the 180 ° hybrid circuit and 7, the component of the frequency f2 will be removed, and the far field will not be disturbed.

As described above, the signals radiated from the transmitting antennas 2 and 3 are received by the receiving antennas 4 and 5, and the levels of the signals received by the receiving antennas 4 and 5 are transmitted from the transmitting antennas 2 and 3. Is very small compared to the signal level. Therefore, the transmission signal receiving circuit 1 is designed to prevent a strong transmission signal from leaking into the receiving circuit 13 and causing interference.
It is desirable that leakage into 3 be minimized. For this reason, in this embodiment, the diameter at which the receiving antennas 4 and 5 are attached is orthogonal to the diameter at which the transmitting antennas 2 and 3 are attached, and the transmission and reception isolation is ensured by changing the plane of polarization.

The signal detected by the receiving circuit 13 is processed by a radar controller 12 together with a cutter head driving distance pulse and a pulse from a rotary encoder (not shown), and is supplied to a signal processing computer 14. Then, necessary data is recorded by the data recording device 15, and the detection result is displayed on the CRT display 17. Further, printing can be performed on recording paper by the color printer 16.

[0030]

As described above, according to the present invention, when the antennas are mounted in the plane of the cutter head, two antennas are on the diameter and one is near the periphery of one of the cutter heads, One is mounted near the other edge of the cutter head, and the two antennas are fed with signals of opposite phase relationship, and the signals to be fed include frequencies that make the diameter of the cutter head half a wavelength. This has an effect that it is possible to detect even a sufficiently distant obstacle practically.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of an antenna mounting structure according to the present invention.

FIG. 2 is a diagram illustrating a connection relationship between a transmission antenna and a reception antenna, and a transmission circuit and a reception circuit.

FIG. 3 is a graph showing a relationship between a frequency transmitted from a transmission circuit and a gain.

FIG. 4 is a block diagram illustrating a configuration of the entire apparatus.

FIG. 5 is a diagram illustrating a standing wave generation state near a cutter head and a generation state of a near field and a far field.

[Explanation of symbols]

 Reference Signs List 1 cutter head 2, 3 transmitting antenna 4, 5 receiving antenna 6, 7 180 ° hybrid circuit 8 rotary joint 11 transmitting circuit 12 radar controller 13 receiving circuit 14 computer for signal processing 15 data recording device 16 color printer 17 CRT display

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-27024 (JP, A) JP-A-61-38099 (JP, A) JP-A-58-77677 (JP, A) JP-A-5-77677 196729 (JP, A) JP-A-2-28586 (JP, A) JP-A-4-131792 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01S 7/00-7 / 42 G01S 13/00-13/95 E21D 9/06 G01V 3/12

Claims (2)

(57) [Claims] 1. An underground radar device for detecting an excavation obstacle ahead of a cutter head for excavating underground, wherein the underground radar device is provided on a first diameter within a cutter head excavation surface and near one peripheral edge of the excavation surface. A first transmitting antenna, a second transmitting antenna provided on the first diameter in the cutter head excavation surface and near the other peripheral edge of the excavation surface, and a first transmitting antenna for transmitting an input signal to the first transmitting antenna. And a 180 ° hybrid circuit for supplying a signal having an opposite phase to the second transmitting antenna, and a high frequency signal in a frequency band including, as the center frequency, a high frequency signal having a half wavelength of the diameter of the cutter head in the 180 ° hybrid circuit. And a transmission circuit for supplying the underwater radar. 2. A first receiving antenna provided on a second diameter orthogonal to the first diameter and near one peripheral edge of a digging surface according to claim 1, wherein the first receiving antenna is provided on the second diameter and A ground comprising: a second receiving antenna provided on the other peripheral portion of the excavation surface; and a 180 ° hybrid circuit that combines signals detected by the first receiving antenna and the second receiving antenna in opposite phases. Medium radar equipment.