JPH0829247A - Buried object detection method and device - Google Patents

Abstract

PURPOSE:To provide a method and device for detecting underground buried object for positively detecting a concrete pipe or a plastic pipe made of, for example, vinyl chloride as well as a metal buried pipe and at the same time discriminating stone and pebble during boring a hole using an earth auger boring machine. CONSTITUTION:The detection device is provided with a vibration sensor 5 for measuring the vibration in up/down directions of a cylindrical casing which is mounted to the inner wall of an earth auger cylindrical casing with a boring blade 3 and a frequency analyzer 6 connected to the vibration sensor 5 and compares not only the spectrum distribution of vibration and the vibration level at a fundamental frequency but also the integral value and peak value of spectrum at a frequency region (a second frequency band) generated when contacting an obstacle with criterion reference values, thus identifying an obstacle and a buried pipe.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the detection of underground buried objects used in excavators, and in particular, underground embedding for excavators for preventing collision damage accidents of existing buried pipes by hole excavators such as earth augers. The present invention relates to an object detection method and device.

[0002]

2. Description of the Related Art In the installation work of electric poles, a hole excavator such as an earth auger is used when the hole excavation work is performed by mechanical excavation. However, in recent years, especially in urban areas, pipeline facilities for lifelines such as gas, water, and electric power are congested in addition to communication cables, and most of these underground buried items are about 2 m underground. Since it exists at a depth within the range, there are often collision damage accidents to the existing buried pipe by the hole excavator.

[0003] Conventionally, as a method for preventing such a collision damage accident of an existing buried pipe, referring to a facility recording map of an underground buried object, an electromagnetic induction type metal buried object detecting device such as a pipe locator or a ground It was to conduct a preliminary survey of the construction site using an electromagnetic underground detection device such as a medium radar.

Further, an earthing tool having a digging blade at the tip of the rotating portion and a cylindrical casing having a lower end peripheral portion formed in a wave shape with a predetermined pitch below the digging blade and having a vibration sensor built in the rotating shaft is provided. With an auger, find the fundamental frequency of vibration that occurs when it comes into contact with a buried object from the number of revolutions of the earth auger and the number of waves per round at the lower edge of the cylindrical casing, and the vibration level at that fundamental frequency is the prescribed vibration. There was a method of judging that an underground buried object was detected when it was higher than the judgment level.

[0005]

However, in the above-mentioned preliminary investigation for preventing the collision damage accident of the existing buried pipe, the equipment record map that can be referred to is inaccurate or has not been updated to the latest data. Or when
It was often difficult to obtain equipment record maps for old buried pipes.

Therefore, it is considered necessary to carry out a preliminary survey by the buried object detection device. However, in the case of the electromagnetic induction method, a major drawback is that the object that can be detected in principle is limited to the metal buried pipe. In addition, it cannot be used in a place where there is a lot of electromagnetic noise, and it cannot be said that the measurement accuracy of the position and depth of the buried pipe is excellent. On the other hand, in the case of electromagnetic waves such as underground radar, radio waves are emitted from the transmitting antenna to the ground, and the reflected waves from the buried pipe can be captured by the receiving antenna, so not only metal pipes but also concrete pipes, plastics such as vinyl chloride The pipe is also detectable. However,
In the electromagnetic wave method, when buried pipes intersect or approach each other, reflected waves interfere with each other, which makes it difficult to accurately determine the position. In addition, there are problems that it is difficult to know the exact position and depth of the buried pipe if the soil quality is uneven or if the water content is high.

Therefore, the method of detecting the existing buried pipe that may exist at the destination of the digging during the hole excavation is very effective in preventing the collision damage accident of the existing buried pipe. However, the method of detecting a buried pipe with an earth auger equipped with a cylindrical casing and a vibration sensor as described above may reach a predetermined vibration judgment level even when it comes into contact with stones, so excavation is temporarily stopped and the buried pipe It was necessary to confirm whether or not. In other words, it can be said that it is very difficult to distinguish the buried pipe from the stone,
There was a drawback that workability was significantly reduced.

As described above, in the conventional method for preventing the collision damage accident of the existing buried pipe in the hole excavation work, it is often difficult to carry out the reliable preliminary investigation, and the detectable buried object. However, it has a drawback that it is limited to metal tubes in most cases. Therefore, there has been a long-felt demand for a method capable of accurately detecting this during drilling a hole, regardless of the material of the buried pipe.

Therefore, the present invention has been made in view of the above circumstances, and during drilling a hole by an earth auger or the like, not only a metal buried pipe, but also a concrete pipe or a plastic pipe such as vinyl chloride can be reliably performed. An object of the present invention is to provide a method and an apparatus for detecting an underground buried object that can be detected and can be distinguished from stones and gravel.

[0010]

In order to achieve the above object, the buried object detecting method according to the present invention firstly comprises a drilling blade at the tip of the rotary shaft and a lower end peripheral portion below the drilling blade. When digging a hole with an earth auger having a pitch-shaped cylindrical casing and a spiral blade for earth removal along the rotation axis, the vibration of the cylindrical casing is measured to measure the underground. A method for detecting a collision with an underground object, comprising: a method for detecting a collision with the underground casing in the first frequency region, which is a frequency region including a fundamental frequency of vibration generated at the time of the collision between the cylindrical casing and the underground object. In the first contact determination vibration level (L0) for determining contact, in the second frequency region which is a frequency region of vibration generated when the lower end peripheral portion of the cylindrical casing comes into contact with an obstacle such as stone or gravel. Contact with obstacles And a contact determination spectrum integral value (S0) for determining the vibration distribution of the cylindrical casing, and a vibration level (L1) in the first frequency region and a spectrum integral value (L1) in the second frequency region. S1) is calculated, and the first contact determination vibration level (L0), the vibration level in the first frequency region (L1), and the contact determination spectrum integral value (S0).
And the spectral integration value (S
It is characterized by judging whether it is an underground buried object or an obstacle such as stone or gravel by comparing 1).

Secondly, according to the buried object detecting method of the present invention, in addition to the first contact determination vibration level (L0) and the contact determination spectrum integral value (S0), the lower end peripheral portion of the cylindrical casing is A second contact determination vibration level (P0) for determining contact with the obstacle is provided in a second frequency region, which is a frequency region of vibration generated when contacting with an obstacle such as stone or gravel, and from the spectral distribution In addition to the vibration level (L1) and the spectrum integral value (S1), the peak value (P1) of the spectrum distribution in the second frequency region is calculated, and the second contact determination vibration level (P0) and the spectrum are calculated. It is characterized in that it is determined whether it is an underground buried object or an obstacle such as stone or gravel by adding comparison of distribution peak values (P1).

Thirdly, the buried object detecting method of the present invention is provided with a rotation speed measuring means for measuring the rotation speed of the rotary shaft, and the basic vibration of the vibration occurring when the cylindrical casing and the underground buried object collide with each other. The frequency is calculated from the rotation speed, the first frequency region and the second frequency region are obtained based on the fundamental frequency, and at least the vibration level (L1) and the second frequency region are calculated.
It is characterized in that a spectrum integral value (S1) in the frequency domain is calculated.

Fourthly, the buried object detecting apparatus of the present invention has an excavating blade at the tip of the rotary shaft and a cylindrical casing below the excavating blade in which a lower end peripheral portion is formed in a wave shape with a predetermined pitch. A vibration sensor for measuring the vibration of the cylindrical casing is provided in the vicinity of the tip of the rotary shaft, and the analysis means for analyzing the output of the vibration sensor is a vibration generated when the cylindrical casing collides with the underground buried object. The first contact determination vibration level (L0) for determining contact with the underground buried object in the first frequency region, which is the frequency region of No. 1, and the lower end peripheral portion of the cylindrical casing is an obstacle such as stone or gravel. And a vertical direction of the cylindrical casing that stores a contact determination spectrum integral value (S0) for determining contact with the obstacle in a second frequency region that is a frequency region of vibration that occurs when Obtains a spectral distribution by measuring the vibration, the vibration level in the first frequency range (L
1) a vibration level calculation unit, a spectrum integration value calculation unit that calculates a spectrum integration value (S1) in the second frequency region, the first contact determination vibration level (L0) and the contact determination spectrum Integrated value (S0)
And the vibration level (L1) and the spectrum integral value (S1) calculated by the vibration level calculator and the spectrum integral value calculator, respectively, to identify the buried pipe and the obstacle such as stone or gravel. And a comparison / determination unit that performs

Fifth, in addition to the above-mentioned fourth structure, the buried object detecting apparatus of the present invention stores a second contact determination vibration level in the storage unit, and the spectrum distribution in the second frequency region. 3. A peak value calculating unit for calculating a peak value (P1) of the spectrum distribution is provided, and it is determined by the buried object detecting method according to claim 2 whether it is an buried object or an obstacle such as stone or gravel. .

Sixthly, the buried object detecting apparatus of the present invention comprises a rotation speed measuring means for measuring the rotation speed of the rotary shaft, and a fundamental frequency of vibration generated when the cylindrical casing and the underground buried object collide. Is calculated from the number of revolutions, and a frequency domain calculation unit for determining the first frequency domain and the second frequency domain based on the fundamental frequency is provided.

Seventhly, the buried object detecting apparatus of the present invention is characterized in that the vibration sensor is provided on the inner wall side of the cylindrical casing.

[0017]

When the hole is excavated with the earth auger, the vibration state of the earth auger can be constantly monitored during the hole excavation by measuring the vertical vibration of the cylindrical casing below the excavating blade. If an embedded pipe exists within the excavation radius during excavation, the lower end of the cylindrical casing first abuts the embedded pipe. However, since the peripheral edge of the lower end of the cylindrical casing is formed in a wavy shape with a predetermined pitch, the embedded pipe is not immediately damaged. At this time, the earth auger produces vertical vibration having a frequency spectrum depending on the number of rotations of the shaft and the peripheral portion of the lower end of the wavy cylindrical casing having a predetermined pitch.

According to the present invention, when a contact is made with an obstacle such as stones or gravel, a spectrum of vibration peculiar to a frequency band higher than the fundamental frequency of vibration shown below is generated in the spectrum distribution of vibration. It has become possible to distinguish between contact with buried pipes and contact with obstacles such as stones and gravel.

Fundamental frequency of vibration f = (a × N) / 60 [Hz] where a is the wave number and N is the rotation number (rpm). Since N is normally excavated at about 20 to 25 revolutions / minute, an approximate fundamental frequency can be assumed in advance. Therefore, by comparing the level of the spectrum distribution and the spectrum integral value of the second frequency band with the higher frequency band (15 to 50 Hz) as the second frequency band in the vicinity of the assumed fundamental frequency, the buried pipe You can judge whether it is an obstacle or an obstacle.

That is, according to the present invention, in order to distinguish an obstacle such as a stone or a gravel from a buried pipe, the vibration level occurs at the fundamental frequency in addition to the vibration level at the fundamental frequency based on the spectrum distribution of the vibration. The integral value and the peak value of the spectrum in the frequency band (second frequency band) are compared with the determination reference value to identify the obstacle and the buried pipe.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1A is a schematic configuration diagram of an earth auger in one embodiment of the present invention, and FIG. 1B is a perspective view showing a cylindrical casing portion in one embodiment of the present invention. In FIGS. 1A and 1B, 1 is a rotating shaft of an earth auger, 2 is a spiral blade for earth removal provided along the rotating shaft 1, and 3 is provided at a tip end portion of the rotating shaft 1. The digging blade 4 is a cylindrical casing in which the lower end peripheral portion provided below the digging blade 3 on the outer peripheral portion of the spiral blade 2 is formed in a wave shape with a predetermined pitch, and 5 is a cylindrical casing attached to the inner wall of the cylindrical casing. A vibration sensor for measuring the vertical vibration of the vehicle, and 6 is, for example, an FFT connected to the vibration sensor 5.
(Fast Fourier transform) A frequency analysis device such as an analyzer.

In the present embodiment, the vibration sensor 5 and the frequency analysis device 6 are connected to each other, and a signal cable 7 for extracting the output of the vibration sensor 5 to the outside is taken out from the rotary shaft 1 as a component. As shown in FIG. 2, a slip ring 8 is interposed above the rotary shaft 1. As shown in FIG. 2, the slip ring 8 is provided with a fixed electrode 9 connected to the vibration sensor 5, and a bearing 10 is provided around the rotary shaft 1.
The sliding electrode 11 is provided so as to slide on the fixed electrode 9 via. The frequency analysis device 6 is connected to the sliding electrode 11.

In addition, in this embodiment, in order to measure the rotation speed of the earth auger, a shaft rotation speed measuring unit (not shown) is provided,
As described above, the fundamental frequency f of vibration is obtained from the number of rotations of the shaft and the number of waves a per revolution of the lower peripheral portion of the cylindrical casing 4. Even if the shaft rotation speed measurement unit is not provided, the rotation speed during excavation is usually 20 to 25 rpm, so the fluctuation of the fundamental frequency f is small. For example, if the wave number is 8, f = 2.6 at 20 rpm.
F = 3.3 Hz at Hz and 25 rpm, and the fluctuation of the fundamental frequency is small at 0.7 Hz. Therefore, the vibration level calculation unit detects the level (L of the detected spectrum) in the frequency range of 2 Hz to 4 Hz (that is, the first frequency range).
1) is output, and the spectrum integration value calculation unit and the peak value calculation unit set the second frequency region that does not include the fundamental frequency f to, for example, 15 Hz to 50 Hz, and each spectrum integration value and spectrum peak value. May be configured to output.

If the wave number changes, the above-mentioned first frequency region and second frequency region can be changed.
On the other hand, in the case of an embedded object detection device equipped with a shaft rotation speed measurement unit, the fundamental frequency corresponding to the rotation speed can be obtained, so that the first frequency region is centered on the fundamental frequency by 1H.
The frequency shift of z, and the second frequency region is set according to the fundamental frequency. For example, the wave number is 8
In case of, if the rotation speed is 15 rpm, the fundamental frequency is 2
Since it is Hz, the first frequency range is 1 Hz to 3 Hz, the second frequency range is 15 Hz to 50 Hz, and the rotation frequency is 25 rpm, the first frequency range is 2.3 Hz to 4.3 Hz, and the second frequency range is the same. Change to. If the shaft rotation speed is measured, an appropriate frequency range can be set according to the rotation speed, so that the accuracy of obstacle determination can be improved.

When the earth auger shown in FIGS. 1 (a) and 1 (b) shown as an example is used, the procedure for detecting an underground buried object is as follows. That is, according to this method, the vibration sensor 5
It is possible to constantly analyze the vibration status of the earth auger during hole excavation by frequency analysis of the output signal of. If an embedded pipe exists within the excavation radius during excavation, the lower end of the cylindrical casing 4 first comes into contact with the embedded pipe. However, since the peripheral edge of the lower end of the cylindrical casing 4 has a sinusoidal shape, the buried pipe is not immediately damaged. At this time, the earth auger produces vertical vibration having a frequency spectrum depending on the number of rotations of the shaft and the shape of the lower end peripheral portion of the cylindrical casing 4 such as a sine wave. Therefore, the vibration of the earth auger is measured by a vibration sensor provided on the inner wall side of the cylindrical casing, and frequency analysis is performed to obtain a frequency spectrum. Then, among the vibrations derived from the shape of the lower end peripheral portion of the cylindrical casing 4, the spectrum intensity (L1) at the fundamental frequency f and the specific frequency region (that is, the second frequency By determining at least the spectrum integral value in the area) and comparing it with a predetermined reference value, it is possible to determine whether it is a buried pipe or an obstacle. Moreover, it does not cause fatal damage to the buried pipe.
The flow of this buried pipe determination is as shown in FIGS.

FIG. 3 is a flow chart of the buried object detecting method of claim 3 corresponding to claim 1. [1] The FFT analyzer of the frequency analysis device 6 samples the waveform received from the vibration sensor 5 at a fixed time.

[2] The vibration spectrum distribution is calculated. [2-1] The fundamental frequency f is calculated from the rotation speed N and the wave number a to determine the first frequency region and the second frequency region.

[3] Only the spectral distribution in the second frequency domain is extracted from the vibration spectral distribution. [4] Calculate the spectrum integration value (S1).

[5] The vibration level (L1) of the fundamental frequency is calculated. [6] The vibration level threshold (L0) is compared with (L1) obtained in [5].

[7] Threshold value of spectral integration value (S
0) and (S1) obtained in [4] are compared. When [8] (L1 <L0), it is determined that there is no buried pipe.

[9] (L1> L0) and (S1 <S0)
When it is, it is judged as an obstacle such as stone or gravel. [10] When (L1> L0) and (S1> S0), it is determined that the pipe is a buried pipe.

The above [1] to [10] are repeated at predetermined time intervals. FIG. 4 is a flowchart of the buried object detection method according to claim 3 corresponding to claim 2.

[1] The FFT analyzer of the frequency analysis device 6 samples the waveform received from the vibration sensor 5 at a fixed time. [2] The vibration spectrum distribution is calculated.

[2-1] The fundamental frequency f is calculated from the rotation speed N and the wave number a to determine the first frequency region and the second frequency region. [3] Only the spectrum distribution in the second frequency domain is extracted from the vibration spectrum distribution.

[4] The spectrum integral value (S1) is calculated. [11] The peak level (P1) of the spectrum in the second frequency domain is calculated. [5] The vibration level (L1) of the fundamental frequency is calculated.

[6] The vibration level threshold (L0) is compared with (L1) obtained in [5]. [7] The threshold value (S0) of the spectrum integrated value is compared with (S1) obtained in [4].

[12] The peak level threshold value (P0) of the spectrum is compared with (P1) obtained in [11]. [13] When (L1 <L0) or (L1> L0)
When (S1> S0) and (P1> P0), it is determined that there is no buried pipe.

[14] (L1> L0) and (S1 <S
When 0) and (P1> P0), it is determined to be an obstacle such as stone or gravel. [15] (L1> L0) and (S1> S0) and (P1
When <P0), it is judged as a buried pipe.

The above [1] to [15] are repeated at predetermined time intervals. 5 (a), (b),
6C, FIG. 6A, FIG. 6B, and FIG. 6C are examples of frequency spectra showing the vibration characteristics of the earth auger before and after the collision with the buried pipe obtained in the experiment by the earth auger of this embodiment. The measurement results are as shown in FIG.
The data is obtained in the case where the lower end peripheral portion of the is formed in a sine wave shape and the wave amplitude is h _pp = 1 cm. The shaft rotation speed at the time of excavation was 20 to 25 rpm, although some rotation unevenness was generated due to the influence of soil unevenness and earth pressure.
FIGS. 5A and 6A are vibration spectra of the earth auger before the buried pipe collision at the time of excavating in the soil. This becomes a so-called background signal before the tip of the earth auger collides with the buried pipe. On the other hand, when it collided with the buried pipe, vibration spectra as shown in FIGS. 5B and 6B were obtained. Also, when the vehicle collides with a stone, FIG.
A vibration spectrum as shown in (c) was obtained. Figure 5
It can be seen that the difference from the vibration spectrum as shown in (b) and FIG. 6 (b) is the spectrum in the range of 10's Hz to 50's Hz. FIG. 5 (b) shows the case where the buried pipe is a vinyl chloride pipe for water supply, and FIG. 6 (b) shows the case where the buried pipe is a steel pipe for gas pipe. In addition, in the figure, the numerical value indicating the wave number is the number of repeated waves per round at the lower edge portion of the cylindrical casing 4 (hereinafter referred to as the casing wave number). Regarding the difference in the vibration spectrum of the earth auger before and after the buried pipe collision obtained in the experiment, the fundamental frequency f
In addition to the fact that the spectral intensity at the slab increases from several times to several tens of times that of the background, it was also found that there is a unique spectrum in the frequency region that occurs only when a stone collides with it. Therefore, according to the underground buried object detection method of the present embodiment, it is possible to identify whether the contact is with the buried pipe or the obstacle such as stones and gravel.

[0040]

As described above, according to the present invention,
Since it is possible to distinguish between a buried pipe and a stone, it is not necessary to frequently stop excavation and check for the presence of a buried pipe in the hole, which greatly improves workability.

Therefore, when some kind of collision is detected during excavation by the buried object detection device, in an urban area where underground pipeline facilities are congested, until now there have been obstacles such as buried pipes, stones and gravel. I had to do it by hand to check if it was something,
Adopting the present invention eliminates erroneous determination due to collision with obstacles such as stones and gravel, so that the range of application of mechanical moat is expanded to 3K.
To improve the work environment, which is said to be (tight, dangerous, dirty),
There is an effect that it can also contribute to solving problems such as a shortage of workers, which is becoming more serious in recent years.

[Brief description of drawings]

FIG. 1 is a configuration explanatory view showing one embodiment of the present invention.

FIG. 2 is a configuration diagram showing a slip ring according to an embodiment of the present invention.

FIG. 3 is a flowchart showing an example of the flow of vibration analysis and buried pipe determination according to an embodiment of the present invention.

FIG. 4 is a flowchart showing another example of the flow of vibration analysis and buried pipe determination according to the embodiment of the present invention.

FIG. 5 is a frequency spectrum diagram showing the vibration characteristics of the earth auger before and after the collision with the buried pipe, which was obtained in the experiment by the earth auger according to the embodiment of the present invention.

FIG. 6 is a frequency spectrum diagram showing the vibration characteristics of the earth auger before and after the collision with the buried pipe, which is obtained by an experiment using the earth auger according to the embodiment of the present invention.

[Explanation of symbols]

1 ... Rotation axis of earth auger, 2 ... Helical blade, 3 ...
Drilling blade, 4 ... Cylindrical casing, 5 ... Vibration sensor, 6 ...
Frequency analysis device, 7 ... Signal cable, 8 ... Slip ring, 9 ... Fixed electrode, 10 ... Bearing, 11 ... Sliding electrode.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kanichi Ogawa 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation (72) Inventor Masahiro Kagoya 1-6, Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation

Claims (7)

[Claims] 1. An excavating blade at the tip of a rotary shaft, and a cylindrical casing having a lower end peripheral portion formed in a corrugated shape with a predetermined pitch below the excavating blade, and a spiral for earth removal along the rotary shaft. When excavating a hole with an earth auger having a circular blade, it is a method of detecting a collision with an underground buried object by measuring vibration of the cylindrical casing, wherein the cylindrical casing and the underground buried object are Of the first contact determination vibration level (L0) for determining contact with the underground buried object in the first frequency range, which is the frequency range of the vibration that occurs at the time of the collision, and the lower end peripheral portion of the cylindrical casing is stone or gravel. And a contact determination spectrum integral value (S0) for determining contact with the obstacle in a second frequency region that is a frequency region of vibration that occurs when contacting with an obstacle such as the vertical direction of the cylindrical casing. Shaking The measures sought spectral distribution, the vibration level (L1) in said first frequency range,
The spectrum integral value (S
1) is calculated. If (L1> L0) and (S1 <S0), it is determined that the pipe has come into contact with the buried pipe, and if (L1> L0) and (S1> S0), the obstacle is touched. A method for detecting an embedded object, which is characterized by determining that 2. The first contact determination vibration level (L0)
In addition to the contact determination spectrum integral value (S0), the lower end peripheral portion of the cylindrical casing is a frequency region of vibration generated when contacting with an obstacle such as stone or gravel.
Second for determining contact with the obstacle in the frequency domain
And a peak value (P1) of the spectrum distribution in the second frequency region in addition to the vibration level (L1) and the spectrum integral value (S1) from the spectrum distribution. , (L1> L0) and (S1 <S0) and (P1 <P0)
In the case of, it is judged that it has contacted the buried pipe, and (L1> L0) and (S1> S0) and (P1> P0)
In the case of (1), it is determined that the obstacle has come into contact with an obstacle such as a stone or gravel, and the buried object detecting method according to claim 1. 3. A rotation frequency measuring means for measuring the rotation speed of the rotation shaft is provided, and a fundamental frequency of vibration generated at the time of collision between the cylindrical casing and the underground buried object is calculated from the rotation speed. 3. The buried object detection method according to claim 1, wherein the first frequency region and the second frequency region are obtained based on a frequency. 4. An excavating blade at the tip of the rotary shaft, and a cylindrical casing having a lower end peripheral portion formed in a wave pattern with a predetermined pitch below the excavating blade, and the cylindrical shape is provided in the vicinity of the tip of the rotary shaft. A vibration sensor that measures the vibration of the casing is provided, and the analysis means that analyzes the output of the vibration sensor is the first frequency region that is the frequency region of the vibration that occurs when the cylindrical casing collides with the underground buried object. A first contact determination vibration level (L0) for determining contact with an underground buried object and a frequency region of vibration generated when the lower end peripheral portion of the cylindrical casing contacts an obstacle such as stone or gravel. A storage unit that stores a contact determination spectrum integral value (S0) that determines contact with the obstacle in the second frequency region, and a spectrum distribution by measuring vertical vibration of the cylindrical casing. Determined, a vibration level calculating unit for calculating a vibration level (L1) in said first frequency range, the spectrum integral value in the second frequency region (S
1), a spectrum integral value calculating unit, the first contact determination vibration level (L0) and the contact determination spectrum integral value (S0), and the vibration level calculating unit and the spectrum integral value calculating unit. The vibration level (L1) and the spectral integration value (S1)
When (L1> L0) and (S1 <S0), it is determined that the contact with the buried pipe is made, and when (L1> L0) and (S1> S0), the obstacle is contacted. An embedded object detection device, comprising: a comparison / determination unit that determines: 5. The contact with the obstacle is determined in the storage unit in a second frequency region, which is a frequency region of vibration that occurs when the lower end peripheral portion of the cylindrical casing comes into contact with an obstacle such as stone or gravel. A peak value calculator of a spectrum distribution that stores a second contact judgment vibration level (P0) and calculates a peak value (P1) of the spectrum distribution in the second frequency region, the first contact judgment Vibration level (L0), the contact determination spectrum integration value (S0), the second contact determination vibration level (P0), the vibration level calculation unit, the spectrum integration value calculation unit, and the peak value calculation unit of the spectrum distribution. Comparing the vibration level (L1) and the spectral integration value (S1) calculated in step 1, and the peak value (P1) of the spectral distribution respectively. Te, (L1> L0) and (S1 <S0) and (P1 <P0)
In the case of, it is judged that it has contacted the buried pipe, and (L1> L0) and (S1> S0) and (P1> P0)
In the case of the above, the embedded object detection device according to claim 4, further comprising a comparison / determination unit that determines that an obstacle such as a stone or a gravel has been contacted. 6. A rotation speed measuring means for measuring the rotation speed of the rotating shaft, and a basic frequency of vibration generated at the time of collision between the cylindrical casing and the underground buried object is calculated from the rotation speed. The embedded object detection device according to claim 4 or 5, further comprising a frequency domain calculation unit that determines the first frequency domain and the second frequency domain based on the above. 7. The buried object detection device according to claim 4, wherein the vibration sensor is provided on the inner wall side of the cylindrical casing.