JPH02157391A - Observation device for wall surface of bore hole - Google Patents

Abstract

PURPOSE:To obtain an observation image of good quality undisturbed due to noise by applying a scanning light beam on a wall face by rotation of a mirror, detecting the observation position due to detection of rotation angle of an encoder plate, and connecting them with optical fiber. CONSTITUTION:A beam from a light source is introduced through an optical fiber 1 and a fixed mirror 7-2, reflected to a slit 11-1 from a rotating mirror 7-1 of the lower side, and irradiated to the wall of a bore hole. Nextly, the reflected beam of the wall of bore hole is reflected to a image formation lens and the reflected beam is taken in the optical fiber 1. Sequentially, an encoder 3 which is connected to an optical fiber 2 and detects rotation angle of a motor is provided, and the rotation angle of the rotating mirror 7-1 is detected from the rotation angle of the motor. The optical observation part and the encoder 3 are connected to a light emitting part and a light receiving part through the optical fiber 2, and an optical signal is processed into an electric signal and transmitted. Hereby, the image signal and detecting signal of good quality can be taken in.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a borehole wall observation device for observing the wall of a borehole such as a polling hole or a pipe hole.

[Conventional technology]

When excavating underground cavities such as dams and tunnels, it is necessary to conduct a geological survey of the construction site, reflect the results in the design, and take every precaution in selecting the construction method to be adopted, how to proceed with construction, and taking safety measures. is necessary.

In geological surveys, it is generally necessary to know the direction, inclination, and properties of rock fractures, as well as the direction and inclination of strata. Survey methods include polling the construction site to collect and observe cores, and directly observing the walls of boreholes.

In polling surveys, polling cores must be taken out to the ground and observed, and during this process, cores that are severely weathered may collapse, resulting in areas that cannot be observed, or data may be collected as stratified average values instead of continuous data. It's stored away. Therefore, when attempting to investigate geology with higher precision, a device that directly observes the wall surface of a borehole is generally an effective means. This device irradiates a light beam onto the inner wall of a borehole while rotating an optical head, receives the reflected light with a charging converter, and converts it into an electrical signal.
There is a borehole wall observation device that obtains a developed image based on the direction and depth of light beam irradiation.
27499, Japanese Patent Application No. 60-26049), its structure will be briefly explained next.

Figure 2 is a diagram showing an example of the configuration of a porehole wall view IM device;
Figure 3 is a diagram showing an example of the configuration of a compass, Figure 4 is a diagram showing the orientation of the compass and the attached status, Figure 5 is a diagram showing an example of the configuration of an inclinometer, and Figure 6 is a diagram showing an example of the configuration of an inclinometer.
The figure shows how the inclinometer is installed.

In FIG. 2, the sonde 11 moves up and down inside the borehole 26 and consists of an observation section that irradiates light onto the wall surface and observes its reflection intensity, and a position detection section that accurately detects the observation position. be.

In the observation section, an optical head 16 including a direction meter 13, a lens 14, and a mirror 15 is connected to a turning motor 12. Also, a light source 22 for sending a light beam to the optical head 16 through a half mirror 19, and a lens 21 for creating a light beam. A slit 20, a slit 17 for detecting the reflected beam from the optical head 16, and a photoelectric converter 18 are provided. With this configuration, the light from the light source 22 is made into a beam by the lens 21 and the slit 20, and is then converted into a beam by the half mirror 19 and the mirror 1.
5. Irradiation is applied to the inner wall of the borehole through the lens 14. The intensity of the reflected beam is then measured by a photoelectric converter 18 through a lens 14, a mirror 15, a half mirror 19, and a pickpocket 17. Therefore, the turning motor 12
When the sonde 11 is lowered without rotating the optical head 16, the inner wall of the borehole is scanned, and an electric signal corresponding to the intensity of the reflected beam is sent to the photoelectric transducer.
It will be obtained from

Wall observation using the observation unit as described above is 1. When the reference position of the sonde 11 is always pointing in a certain direction using the built-in direction indicator 13, the direction from the reference position is checked. However, if only the direction indicator 13 is used, the borehole must be completely vertical, otherwise the observation accuracy will be significantly reduced. Therefore, a position detection unit is used to accurately determine the observation position even if the borehole is not vertical but curved.

The position detection unit is provided with a compass 23 and an inclinometer 25 as means for measuring the opening of the hole, and a rotation meter 24 as a means for measuring the orientation of the optical head.

The compass 23 is attached to a first fulcrum A that is rotatable about a line l that coincides with the axial direction of the sonde 11, for example as shown by a dotted line in the figure.
It is attached to the sonde 11 at fulcrums A and A' via %A' and second fulcrums Q and Q' which are rotatable around a line m perpendicular to line l, and the measuring section is mounted from the ground. It is supported in a constant state in the vertical direction. Figure 3 shows the specific configuration of the compass.
, an encoder plate 35, a light emitting section 37, and a light receiving section 36 are built in, and the inclination direction angle of the sonde 11 is measured. Similarly, the inclinometer 25 has fulcrums R and R' that are rotatable around the line l, and is attached to the sonde 11 at a point BSB', so that the measuring part moves along the line β in accordance with the inclination of the sonde 11. It rotates around it. The specific configuration is as shown in FIG.
7. A light receiving section 46 is built in to measure the inclination angle of the sonde 11. Further, the tachometer 25 is installed at a position where the compass 23 is attached to the fulcrum, and measures the direction E that is the reference of the sonde 11. The condition of each installation is shown in the fourth column.
FIG.

[Problem to be solved by the invention]

However, the borehole wall observation device as described above is
Because the electrical signal wire is pulled to the tip of the sonde,
Depending on the conditions of use, there are problems such as easy noise and unstable operation. For example, in geological surveys such as geothermal power generation, they are used in high temperatures, so if the operation of the image signal processing circuit, compass, inclinometer, etc. becomes unstable, the observed images will be distorted.
There is a problem that the accuracy of the observation position deteriorates. Moreover,
Because it falls deep into the earth, it is not possible to accurately determine thermal or electrical conditions, and there are some areas where it is unpredictable.

The present invention solves the above-mentioned problems, and aims to provide a borehole wall observation device that is resistant to noise and can obtain high-quality observation images.

[Failure to solve the problem]

To this end, the present invention provides a borehole wall observation device that moves up and down in a borehole, irradiates the wall surface with light, captures the reflected light, and observes the wall surface, and includes a mirror and scans a light beam by rotating the mirror. The optical system is equipped with an optical system and a slit that irradiates the wall surface while taking in the reflected beam from the wall surface, and an encoder plate, and a position detection means that optically detects the rotation angle of the encoder plate and detects the observation position. The system is characterized in that an optical fiber connects the observation section of the system and the detection section of the position detection means to the light emitting section and the light receiving section.

[Effect]

In the borehole wall observation device of the present invention, an optical fiber is used to connect the observation section of the optical system and the detection section of the position detection means to the light emitting section and the light receiving section. The light-emitting section and the light-receiving section can be disposed at a position above and away from the tip to perform electrical signal processing and transmission.

〔Example〕

Examples will be described below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of the borehole wall observation device according to the present invention, in which 12.2' is an optical fiber;
is a light source, 3 is an encoder, 4 is a motor, 5 is a gear drive mechanism, 6 is a rotating cylinder, 7-1 is a rotating mirror, 7-2 is a fixed mirror, 8 is a compass, 8-1 and 9-1 are encoders Board, 9
1 is a tachometer, IO is an inclinometer, 11 is a sonde, and 11-1 is a slit.

In FIG. 1(a), optical fibers 1 and 2 have a light emitting part (light source) and a light receiving part (photoelectric conversion element) arranged at their ends (not shown), and are located on the ground away from the tip of the sonde 11. Or configure the optical system up to a position close to the ground,
The light source and the photoelectric conversion element can be placed on or near the ground. The optical fiber 1 is for transmitting an optical signal for observing the hole wall, and the optical fiber 2 is for
Optical signal for observation position detection (angle signal by encoder)
It is intended to transmit. The rotating barrel 6 is a rotating mirror 7-1.
are fixed at positions above and below the center of rotation, and are rotationally driven by a motor 4 via a gear drive mechanism 5. A fixed mirror 7-2 is provided opposite to the lower rotating mirror 7-1, and a beam from a light source is introduced through the optical fiber 1 and the fixed mirror 7-2, and the beam from the lower rotating mirror 7-1 is introduced to the lower rotating mirror 7-1. -1 to slit 1t-1 and irradiates the hole wall.

Then, the reflected beam from the hole wall is reflected from the upper rotating mirror 7-1 toward the imaging lens, and the reflected beam is taken in by the optical fiber 1. Encoder 3 is optical fiber 2
It detects the rotation angle of the motor in combination with the light emitting part and light receiving part connected to the rotating mirror. A rotation angle of -1 is detected. By making the shaft of the motor 4 connected to the gear drive mechanism 5 long as shown in the figure, the shaft of the motor 4 can be positioned further away from the tip of the sonde 11.
It is possible to place .

Pickpocket 1) 11-1 uses a member that transmits the irradiated light and reflected light, but if only transparent glass or resin is used, the irradiated light will be reflected at this part and cause noise on the image. appear. Therefore, for example, if a wavelength in the near-infrared region is used as the optical signal, or if a member with polarization characteristics is used as the pickpocket 1) 11-1, the above noise can be reduced.

The compass 8 and the inclinometer 10 are the same as those shown in FIGS. 3 and 5, but between these encoder plates, the light emitting part, and the light receiving part, an optical fiber 2 is provided above the sonde or on the ground. Connected with

The tachometer 9 similarly consists of an encoder plate, and is connected to the light emitting section and the light receiving section through the optical fiber 2.

By the way, the longer the optical fiber connected to the light source,
Especially if the round trip to the ground is guided by optical fiber,
In some cases, an amount of light several tens of times larger than that of the optical sensor section is required. In such a case, if an optical fiber is used, a problem arises in that the amount of light introduced is limited and a sufficient amount of light cannot be obtained. On the other hand, some lamps are heat resistant and can be used as a light source even in an atmosphere with high geothermal heat of 200° C. or higher. Examples include halogen lamps. Therefore, 20
For wall observation in an atmosphere with a high temperature of about 0°C, a lamp 1-1 is installed as a light source near the observation mirror 7-1 inside the sonde 1, as shown in Fig. −
1 to illuminate the wall surface, and each encoder plate 8-L9- from this light source 1-1 passes through an optical fiber 2'.
You can lead to 1st prize. In this way, even if the light from the light source is used directly or an optical fiber is used, the length of the optical fiber that is pulled to the position where the light is introduced becomes shorter, so that a sufficient amount of light can be supplied. That is, in this configuration, power is supplied to the sonde 11 for driving the motor 4 and lighting the light source 1-1. Then, only the reflected light from the wall surface and the light receiving side of each encoder plate are guided to the optical sensor of the ground signal processing device, and the optical signals are converted into electrical signals and processed on the ground.

Note that the present invention is not limited to the above embodiments, and various modifications are possible. In the above embodiment, a transmission type is used as the rotation angle detection method, but a reflection type rotation angle detection method may be used in which a light emitting section and a light receiving section are arranged as a pair on one side of the encoder plate. Further, although rotating mirrors are provided above and below the rotating tube, only the irradiation side may be rotated, and the intake side may be a conical mirror.

The light emitting section where the light source is placed and the light receiving section where the photoelectric conversion element is placed may be installed at the top of the sonde in order to keep the optical fiber as short as possible, but considering the geological conditions to be observed, etc. It goes without saying that the structure may be appropriately selected, such as being provided between the two or on the ground.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the observation section and position detection section at the tip of the sonde are configured with an optical system, and a noise-resistant optical signal is transmitted to a place with little noise and then converted into an electrical signal. Since the image signal and the detection signal are processed, high-quality image signals and detection signals can be extracted. Moreover, since the image signal and detection signal are transmitted as optical signals using optical fibers to a position in a favorable environment and then converted into electrical signals, it is possible to obtain high-quality observation images with little noise, and also to obtain highly accurate positioning. Detection can be performed.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an embodiment of the borehole wall observation device according to the present invention, Fig. 2 is a diagram showing an example of the configuration of the borehole wall observation device, Fig. 3 is an example of the configuration of a compass, and Fig. 4 is a diagram showing the azimuth. FIG. 5 is a diagram showing a configuration example of the inclinometer, and FIG. 6 is a diagram showing the installation state of the inclinometer. 1 and 2...optical fiber, 3...encoder, 4...
... Motor, 5 ... Gear drive mechanism, 6 ... Rotating cylinder,
7-1...Rotating mirror, 7-2...Fixed mirror, Death...Direction meter, 9... Rotation meter, 10... Inclinometer, 11
...Sonde, 11-to...slit. Applicant: Central Research Institute of Electric Power Industry (2 others) Representative Patent Attorney Ryukichi Abe (5 others) Figure 1 Figure 6 (G) Figure 2 Figure 4

Claims (2)

[Claims] (1) A borehole wall observation device that irradiates the wall surface with light from a sonde that moves up and down in the borehole, captures the reflected light, and observes the wall surface.It has a mirror and scans the light beam by rotating the mirror. An optical system and slit that irradiates the wall surface while capturing the reflected beam from the wall surface,
and a position detection means having an encoder plate and optically detecting the rotation angle of the encoder plate to detect the observation position,
A borehole wall observation device characterized in that an optical fiber is used to connect an observation section of an optical system and a detection section of a position detection means to a light emitting section and a light receiving section. (2) The light source of the light emitting part is placed in the sonde, and the light source is configured to irradiate the wall surface through the mirror and introduce the light to the encoder plate through the optical fiber. Borehole wall observation device.