JPH02101283A - Borehole wall observation device - Google Patents

Abstract

PURPOSE:To improve detection precision by connecting the observation section of an optical system, the detection section of a position detecting means and a light reception section with an optical fiber. CONSTITUTION:The light from a light source 7-2 is reflected from a rotary mirror 7-1 on the lower side toward a slit 11-1 and radiated to a hole wall. The reflected beam on the hole wall is reflected from a rotary mirror 7-1 on the upper side toward an image forming lens and extracted through an optical fiber 1. The rotation angle of a motor 4 is detected by an encoder 3 with a light source, the detected light signal is sent to a light reception section via an optical fiber 2, and the rotation angle of the rotary mirror 7-1 is detected. Detected light signals from a goniometer 8, a tachometer 9 and a clinometer 10 with light sources respectively are sent to the light reception section via the optical fiber 2.

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 constructing dams, tunnels, etc., the underground bedrock is used as 11 or excavated to form a cavity. However, a geological survey of the construction site is conducted in advance, and the results are reflected in the design and the selection of the construction method to be adopted. It is necessary to take all possible precautions in the construction process and safety measures.

In geological surveys, it is generally necessary to know the direction, width, and slope of fractures in rock, as well as the direction and slope 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 parts that cannot be observed, or they cannot be collected as continuous data, so it is difficult to collect data based on stratified average values. It's stored away. Therefore, when attempting to investigate the geology with higher accuracy, a device that directly observes the wall surface of the borehole at -i is an effective means. This device irradiates a light beam onto the inner wall of the borehole while rotating an optical head, receives the reflected light with a photoelectric converter, and converts it into an electrical signal.The device generates an image based on the direction and depth of the light beam. There is a borehole wall observation device that obtains
7499, Japanese Patent Application No. 60-26049), its structure will be briefly explained next.

Figure 2 shows an example of the configuration of a borehole wall observation device, Figure 3 shows an example of the configuration of a compass, Figure 4 shows how the compass is installed, and Figure 5 shows an example of the configuration of an inclinometer. The figure shown in FIG. 6 is a diagram showing 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, a lens 21 for creating a light beam, a slit 20, and a light source for detecting a reflected beam from the optical head 16. A slit 17 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 irradiated onto the inner wall of the borehole through the half mirror 19, the mirror 15, and 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 slit 17. Therefore, the turning motor 1
2, 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 transmitted to the photoelectric converter 1.
It will be obtained from 8.

Wall observation by the observation unit as described above is performed while checking the direction from the reference position when the reference position of the sonde 11 is always pointing in a certain direction using the built-in direction indicator 13. 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 hole surface radius, 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 P that coincides with the axial direction of the sonde 11, for example as shown by a dotted line in the figure.
, A', and second fulcrums Q, Q' which are rotatable around a line m perpendicular to the line β, are attached to the sonde 11 at the fulcrums A and A', and the measurement unit is mounted on the sonde 11 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 'yAl.
', and is attached to the sonde 11 at points B and B', and the measuring part rotates around the line P in accordance with the inclination of the sonde 11. As shown in FIG. 5, the specific configuration includes an encoder plate 45 to which a weight 44 is attached, a light emitting section 47, and a light receiving section 46, and measures the inclination angle of the sonde 11. Furthermore, the tachometer 25 is attached to the direction meter 23 at the fulcrum A, and the direction E is the reference point for the sonde 11.
is being measured. FIGS. 4 and 6 show the respective installation states.

[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 is lowered deep into the earth, thermal or electrical conditions cannot be accurately determined and are sometimes 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.

[Means to solve the problem]

To this end, the present invention provides a borehole wall observation device that irradiates the wall surface with light from a sonde that moves up and down or horizontally within the borehole, captures the reflected light, and observes the wall surface, and has a mirror inside the sonde. It has an optical system, a slit, and an encoder plate that irradiates the wall surface while scanning the light beam by rotating the mirror and captures the reflected beam from the wall surface, and optically detects the rotation angle of the encoder plate to detect the °ζ observation position. The present invention is characterized in that it includes a position detecting means for detecting a position and a light source, and an optical fiber connects the observation section of the optical system and the detection section of the position detecting means to the light receiving section.

(Function) In the borehole wall observation device of the present invention, a light source is placed inside the sonde to irradiate the wall surface and the encoder plate of each position detection means with light, so that a sufficient amount of light is required for wall observation and position detection. In addition, the optical signals for wall observation and the detection optical signals for each position detection means are transmitted through optical fibers in areas where the environment is poor and there is a lot of noise, such as the tip of the sonde, so detection accuracy can be increased. .

〔Example〕

Examples will be described below with reference to the drawings.

FIG. 1 is a diagram showing one embodiment of the borehole wall observation device according to the present invention, in which 1.2.2' is an optical fiber, 3 is an encoder, 4 is a motor, 5 is a gear drive mechanism, 6 is a rotary cylinder, 7-1 is a rotating mirror 7-2 is a light source, 8 is a compass, 8
-1 and 9-1 are encoder plates, 9 is a tachometer, 10 is an inclinometer, 11 is a sonde, and 11-1 is a slit.

In FIG. 1(a), the optical fiber 1.2 has a light receiving section (photoelectric conversion element) arranged at its end (not shown), and is connected to a position far from the tip of the sonde 11, at or near the ground. is constructed with an optical system, and the photoelectric conversion element can be placed on the ground or in a position close to the ground.

The optical fiber 1 is for transmitting an optical signal for observing the hole wall, and the optical fiber 2 is for transmitting an optical signal (for detecting the observation position).
The angle signal generated by the encoder is transmitted. The rotating barrel 6 has a rotating mirror 7-1 fixed above and below the center of rotation, and is rotationally driven by the motor 4 via the gear drive mechanism 5. A light source 7-2 is arranged to face the lower rotating mirror 7-1, and the lower rotating mirror 7-1
The light is reflected from the light toward the slit 11-1 and irradiates the hole wall. Then, the reflected beam from the hole wall is transferred to the upper rotating mirror 7-1.
The encoder 3, which reflects the reflected beam from the optical fiber 1 toward the imaging lens and captures the reflected beam from the optical fiber 1, detects the rotation angle of the motor in combination with a light emitting section and a light receiving section.
It is configured to have a light source as a light emitting section and to transmit a detection optical signal to a light receiving section through an optical fiber 2. and,
The rotation angle of the rotating mirror 7-1 is detected from this signal.

The shaft of the motor 4 connected to the gear drive mechanism 5 is made long as shown in the figure, so that the motor 4 can be placed at a position farther away than the tip of the sonde 11.

The slit 11-1 is made of a member through which the irradiated light and the reflected light can pass, but if only transparent glass or resin is used, the irradiated light will be reflected at this portion and appear as noise on the image. Therefore, for example, if a wavelength in the near-infrared region is used as the optical signal, or if a member with polarization properties is used as the slit 11-1, the above noise can be reduced.

The direction meter 8 and the inclinometer 10 are the same as those shown in FIGS. 3 and 5, but each has a light source as a light emitting part, and the light reception signal of the encoder plate is transmitted to the light reception unit above the sonde or on the ground. The optical fiber 2 connects all the way to the end. Similarly, the tachometer 9 is connected by the optical fiber 2 from the encoder plate to the light receiving section.

Note that it is also possible to configure the light emitting part to be paired with the light receiving part and introducing light from the position of the light receiving part to the wall observation part or sensor using an optical fiber, but if the optical fiber connected to the light source is long, it will be difficult to reach the ground. If the round trip is guided by an optical fiber, the amount of light may be several tens of times greater than that of the optical sensor unit. 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, there is a heat-resistant lamp that can be used as a light source even in a high temperature atmosphere of 200° C. or higher due to geothermal heat, such as a halogen lamp. Therefore, the above configuration can be adopted for wall surface observation in an atmosphere at a high temperature from room temperature to about 200''C.

In addition, as shown in FIG. 1(b), a light source 7- for wall surface observation is provided.
2 may directly illuminate the wall surface through the mirror 7-1, and may also guide this light m7-2 through the optical fiber 2' to each encoder plate 8-1. Directly utilizes light from
Although an optical fiber is used in the position detection section, the length of the optical fiber that is pulled to the position where light is introduced becomes shorter, so that a sufficient amount of light can be supplied to the position detection section as well. That is, in this configuration, power is supplied to the sonde 11 for driving the motor 4 and lighting the light source. Then, only the optical signal of the wall surface observation and the detection signal of each encoder plate are guided to the optical sensor of the ground signal processing device, and the optical signal is converted into an electrical signal 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 was used as the rotation angle detection method, but a reflection type rotation angle detection method in which a light emitting part and a light receiving part are arranged as a pair on one side of the encoder plate may also be used. 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. Furthermore, in the example shown in FIG. 1, the light from the light source 7-2 is directly received and reflected by the mirror 7-1, but in cases where the amount of light is insufficient, it is necessary to ensure a sufficient amount of light. If necessary, light tA7-
By placing a lens between the mirror 7-1 and the mirror 7-1 to condense the light, a strong beam of light may be reflected by the mirror 7-1 and illuminated on the wall surface.

The light receiving part where the photoelectric conversion element is placed may be installed at the top of the sonde to make the optical fiber as short as possible, but it may be installed between the sonde and the ground, or on the ground, taking into consideration the geological conditions to be observed. It goes without saying that the configuration may be configured such that the following information is selected as appropriate.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the optical signals from the observation section and position detection section at the tip of the sonde are transmitted as they are through the optical system, so it is possible to eliminate the electrical signal processing circuit from the observation section, which has a poor environment. can.

Moreover, since the image signal and detection signal are transmitted as optical signals using optical fibers to areas with a favorable environment and then converted into electrical signals, it is possible to obtain high-quality observation images with little noise, and to obtain highly accurate positioning. Detection can be performed.

[Brief explanation of drawings]

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. 1.2.2'... Optical fiber, 3... Encoder, 4... Motor, 5... Gear drive mechanism, 6... Rotating tube, 7-1... Rotating mirror, 7-2 ...light source, 8
... Direction meter, 9... Rotation meter, 10... Inclinometer, 1
1...sonde, 11-1...slit. Applicant Shimizu Corporation (1 other person) Agent Patent attorney Ryukichi Abe (5 others) Figure 6, 31 Figure 4

Claims (3)

[Claims] (1) A borehole wall observation device that irradiates the wall surface with light from a sonde that moves up and down or horizontally within the borehole, captures the reflected light, and observes the wall surface;
It has an optical system that scans a light beam by rotating the mirror and irradiates it onto the wall and captures the reflected beam from the wall, an encoder plate, and optically detects and observes the rotation angle of the encoder plate. A borehole wall observation device comprising a position detection means for detecting a position and a light source, and an optical fiber connecting an observation section of an optical system and a detection section of the position detection means to a light receiving section. (2) The borehole wall surface observation device according to claim 1, wherein a light source is disposed in each of the observation section of the optical system and the detection section of the position detection means. (3) A light source is disposed in the observation section of the optical system, and the light source is configured to irradiate the wall surface via a mirror and introduce the light to the encoder plate through an optical fiber. borehole wall observation device.