Apparatus for inspecting anchor boreholes

CA 02565254 2006-11-01

APPARATUS FOR INSPECTING ANCHOR BOREHOLES

The invention relates to an apparatus for inspecting anchor boreholes and comprises a probe that has an optical acquisition device and that can be moved in the borehole with a pipe string.

US 5,663,559 describes a method and an apparatus for producing an image of an earth formation in oil-prospecting bores.

EP 0658 253 Bl discloses a borehole observation instrument for inspecting the interior of a borehole or shaft in oil prospecting bores.

WO 94/07147 Al relates to a method of and an apparatus for simultaneous video-technical determination of the flow direction and speed of groundwater for bore diameters > 2 inches.

The methods and apparatuses disclosed in these publications are not suitable for inspecting anchor boreholes because anchor boreholes generally have a diameter of 1 to 2 inches .

It is known from DE 199 25 733 C2 that boreholes can be viewed visually with an endoscope (borehole endoscopy).

With such endoscopy, the borehole wall is visually inspected on-site; it is not possible to store the observation and a true spatial depiction of the layer data for the rock structure.

The main object of the invention is to provide an apparatus with which it is possible to optically survey the borehole wall of anchor boreholes and to evaluate the information obtained in this manner such that a safety-relevant evaluation of the condition of the rock and objective documentation during driving of the bore are obtained.

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This object is obtained using the features in claim 1.

Further embodiments are provided in the subordinate claims .

The inventive anchor-borehole probe, which is made as a wireless, i.e. autarchic probe, is moved along the anchor borehole and the surface of the borehole is visually and digitally scanned and stored. This enables documentation of the borehole wall, which can be used to determine the true spatial position of discontinuities and strata by means of an evaluation program. The evaluation program enables uncomplicated administration of the data in a data bank, image processing, and evaluation and interpretation of the borehole images.

The anchor-borehole probe is made explosion-proof for use in underground coal mines.

Travel detection is performed using a contact wheel on which a motion sensor is arranged for determining the travel. It is also possible for the probe movement to be acquired directly with a motion sensor. This motion sensor radiates onto the borehole wall and the reflections during movement of the probe are detected and the travel is determined therefrom.

Using the integrated position sensors, the position of the probe in the borehole is acquired and stored together with the image information. A determination of the true position of the discontinuities is made using the evaluation program and includes the probe spatial position data.

The stored digital image of the surface of the borehole wall is used for structural analysis and for analyzing lithological and petrographical properties.

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The true spatial positions of the discontinuities and their frequency distribution are used to determine the fissure bodies in the ends of a path or in the head of a tunnel. The considerable travel into the borehole provides optimized, independent and objectively comparable information on the course and condition of the fracture and condition of the segment head.

Using the evaluation program and the database it is possible to compare data from older inspections with more recent inspection results so that changes in the fracture openings can be detected. This prompt recognition of fracture zones makes it possible to take action early on. It is thus possible to assess the rock structure's condition in terms of safety at any time. In addition, information regarding the rock structure's properties is very important during planning and optimization of the path supports and particularly anchor dimensioning. If there are any problems when driving, the anchor borehole can be documented quickly.

Power is supplied to the anchor-borehole probe using conventional Mignon batteries. The images of the borehole walls are acquired digitally using a color CCD sensor and are stored in the probe. The memory can hold a plurality of measurement operations so that the probe does not have to be read out after each measurement. Monitoring and calibration of the anchorborehole probe is done by a mobile PC using a high-speed infrared interface integrated into the battery section at the rear end of the probe. The data acquired can also be read out via this infrared interface.

Normally the recordings taken with the anchor-borehole probe are copied out of the probe memory using a USB read-out box

CA 02565254 2006-11-01 and are imported by the software. An assistant supports input of specific additional information for each measurement. Possible additional information includes supplementary comments on the data regarding borehole length and diameter and classification of locations and boreholes, if these have already been defined during earlier measurements.

In addition, there are numerous options for graphics processing of the digital images recorded by the probe. The technician can for instance crop the images; change brightness, contrast, intensity, and gamma value; adjust sharpness; and smooth.

The images can be rotated and aligned on their axial orientation. In addition there is a clean-up function for eliminating measurement artifacts.

Using the software, sufficient data for the rock structure that has been bored through can be determined from the borehole images. Determination of the discontinuity orientation is performed semi-automatically by picking (clicking on) and classifying the types (e.g., fracture, stratum surface) of the structures that can be seen in the image. The evaluation program can be used for additional processing of the spatial position data for the probe to determine the true spatial positions of the discontinuities. Lithological description of the corresponding depths is also possible.

Rock identification and establishment of limits thus occurs in the framework of the evaluation, as does the determination of the scope and degree of fracture zones. All of the data are stored in the database for documentation and repeat measurements .

CA 02565254 2006-11-01

The structures are marked both in the image of the borehole wall and in various 3D-views as surfaces. Initially 2D forms are created for individual cross-sections of the path using borehole endoscopy; in addition the software permits a 3Drepresentation of the boreholes (position in the tunnel/path/bore problem with discontinuity structure).

Using the image data archived and stored in the data base and the information about the borehole (location, spatial position, dimensions, tunnel profile, etc.), it is possible to compare current measurement data to measurements in the same borehole that were taken at an earlier point in time or to data for adjacent boreholes. In this manner it is possible to determine the type, extension, and appearance time of weak zones in the path.

In one preferred embodiment, the anchor-borehole probe is a wireless autarchic optical probe with a diameter of 23 mm. It is thus suitable for digital imaging of the walls of boreholes that have a diameter of 25 to 37 mm. Due to its small diameter and light weight, the probe can be moved manually in the borehole using extension rods.

The borehole probe constitutes a video head, a path sensor, an electronics module, a memory module, and a battery element that also holds an infrared interface. Data transmission makes it possible to monitor inspections.

Imaging is controlled using the path sensor, which in addition to imaging control also provides depth measurement and thus the option for precisely measuring structures, e.g. discontinuity distances and RQD indices, determining crack width, stratum thicknesses, etc.

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The true spatial position of the discontinuity structure can be determined using the position sensor values.

The invention is described in greater detail in the following using an illustrated embodiment and drawings.

FIG. 1 is a schematic depiction of the method for determining the rock structure in the path lining;

FIG. 2 is a section through the video head;

FIG. 3 is an overall depiction of the anchor-borehole probe ;

FIG. 4 is a schematic

FIG. 5 is a schematic borehole.

Example

An anchor borehole is following specifications.

Power supply:

Data memory:

Probe length:

Probe diameter

Probe weight :

Sensor :

Measurement cycle:

Measurement speed:

11luminat ion :

Depth measurement :

depiction of the travel sensor;

depiction of the video head in a inspected with a probe that has the x Duracell MN 1500, 1.5V

256 MB

1,300 mm mmm [sic]

2.2 kg

COLOR CCD

Max. 25 images per second

Max. 5 cm per second white light-emitting diodes

Wheel-driven travel sensor

The probe is moved along the borehole using a pipe string. Bars built into each coupling ensure good control of the orientation of the probe in the borehole. The anchor-borehole probe scans an angle of 360 degrees, i.e. it covers the entire

CA 02565254 2006-11-01 borehole wall. In the two-dimensional image of the borehole wall surface, which corresponds to a cylinder surface, the borehole wall is shown unrolled. What this leads to is that planar structures, such as e.g. stratum surfaces, fissures, etc. that are not exactly perpendicular to the axis of the borehole appear as sinusoidal lines in this view. The true spatial position and frequency of the fissure surfaces can be detected and illustrated by inspection with the probe .

FIG. 1 provides a schematic representation of the method for inspecting anchor boreholes for determining the rock structure in the path lining. An anchor-borehole probe 1 is moved along an anchor borehole 2 using a pipe string. The bore 3 has additional boreholes 2'. The structure of the rock 4 can be analyzed using the anchor-borehole probe 1. The anchor-borehole probe 1 is positioned in the anchor borehole 2 in the area of a crack 5. The video head is used to digitally record a two-dimensional image 6 of the borehole wall surface.

As can be seen in FIG. 2, a video head 10 has a color CCD sensor 11 that has a lens 12. Using a conical mirror 13, it is possible to optically digitally acquire the borehole wall, which is illuminated by light-emitting diodes 15, through a viewing window 14. A plug connector 16 is provided at the lower end of the video head 10.

FIG. 3 illustrates the anchor-borehole probe 1. It constitutes the video head 10, the travel sensor 20, an electronics module 21, a memory module 22, and a battery section 23 that also contains an infrared interface 24. Two position sensors 25 and 26 are provided in the electronics module.21. The individual

CA 02565254 2006-11-01 constituent parts of the anchor-borehole probe 1 are joined to one another using plug-in connectors 16.

As can be seen from FIG. 4, the travel sensor 20 comprises 3 spring-mounted wheels 30, 30', and 30'' that are arranged offset by 120 degrees. A motion sensor 31 is provided on the wheel 30 for determining the travel distance of the anchorborehole probe 1. Because of space considerations, the movement of the wheel 30 is transmitted to gears 32 and detected by the motion sensor 31.

It can be seen from FIG. 5 that the video head 10 of the anchor-borehole probe 1 is positioned in the anchor borehole 2.

The wall of the anchor borehole 2 is illuminated with the lightemitting diodes 15 using a conical beam of light 35. Depending on the travel, the borehole wall of the anchor borehole 2 is visually 15 digitally acquired in the area of the beams 36 using the color CCD sensor 11. This image of the borehole wall is stored using the evaluation program and inspected semi-automatically using a menu control. This is how the structure of the rock 4 is determined.

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Reference list

Anchor-borehole probe

Anchor borehole

2¹ Anchor borehole

Path

Rock structure

Crack

Two-dimensional image

Video head

Color CCD sensor

Lens

Conical mirror

Viewing window

Light-emitting diodes

Plug-in connector

Travel sensor

Electronics module

Memory module

Battery section

Infrared interface

Position sensor

Position sensor

Wheel

30' Wheel

30'' Wheel

Motion sensor

Gears

Conical beam of light

Beams