Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
  • G01C7/00—Tracing profiles
  • G01C7/06—Tracing profiles of cavities, e.g. tunnels

Definitions

• the subject invention concerns a method and an apparatus for the determination of the volume of rock chambers.
• the apparatus is designed to be used to establish the exact volume of the rock chamber as the blasting is progressing.
• the intended purpose of the blasted rock chamber may be as a subterranean storage room, a bomb shelter or a tunnel.
• the light beams from the illuminated point on the rock chamber wall are reflected to an optical instrument and is refracted by means of a lens to a point the distance of which from the longitudinal axis of the tunnel is measured automatically. This distance is propor ⁇ tional to the distance between the longitudinal tunnel axis and the tunnel wall and in this manner it becomes possible to establish the distance.
• the measured value is but a proportional part of the sought-after value, with the result that all errors and uncertainties of the read- -off values are enlarged by several times.
• the measurements are per ⁇ formed automatically, which means that no regard is paid to whether or not the read-off measuring point is positioned in a representative part of the profile of the area. For instance, the measuring point might be positioned on a protruding rock formation. The unreliability of the measuring results thus is considerable.
• This prior-art device obviously is intended to establish the area of the tunnel, not its volume, since it is not designed to coor ⁇ dinate a number of area-determination values to establish the volume of the rock chamber.
• Such coordination may be obtained only after the de- termination of the distance between various parallel measuring planes.
• the device is difficult to use, since it cannot be driven into the tunnel until after completion of the blasting of the tunnel when the rail is deposited. It is obvious therefore, that this device is not intended for the continuous measurement of the volume of the rock chamber while the work of blasting the latter is still in progress.
• One purpose of the subject invention is to provide a method for the exact measurement of the volume of a rock chamber as the blas ⁇ ting of the latter is progressing.
• a further purpose of the invention is to provide a simple and inexpensive apparatus for performing the method.
• the characterizing features of the method in accordance with the invention appear above all from claim 1.
• the apparatus in accor ⁇ dance with the invention is characterized primarily by the features appearing in claim 5. Further characteristics of the invention appear from the dependent claims.
• Fig. 1 is an overall perspective view of the apparatus in accordance with the invention
• Fig. 2 is a diagram illustrating ray paths an sight lines for performing the measuring method in accordance with the invention.
• the apparatus in accordance with the invention comprises a source of light which in the embodiment illustrated is a laser 10 emit ⁇ ting a laser beam 12.
• the laser 10 is positioned at the mouth of a rock chamber the blasting of which is in progress and the laser beam 12 is directed essentially in the lengthwise direction of the rock chamber.
• An optical deflecting member in the form of a prism is positioned in the interior of the rock chamber and in such a position that it is struck by the aser beam 12.
• the beam is deflected at righ angles and the deflected beam 16 strikes the rock chamber wall 18 and illuminates a spot 20 on the latter.
• An optical instrument in the form of a theodolite 22 is provided in the rock chamber laterally of the laser beam 12.
• the theodo ⁇ lite 22 is of a conventional kind and well known from the land sur ⁇ veying technology.
• the prism 14 preferably is a pentagon prism which is ar ⁇ ranged in such a manner that the deflected beam 16 will always be directed in a plane which extends at right angles to the beam 12 which is incident on the prism.
• the prism 14 is rotationally mounted in such a manner as to ensure that the deflected laser beam 16 may be directed in various directions in this plane which is perpendicular also to the main extension of the rock chamber.
• the rotation of the prism is effec ⁇ ted by means of a remote-controlled motor which preferably is operated by infrared light. Radio-control of the motor would mean a safety risk because of the presence of the blasting equipment inside the rock cham- be.r.
• the remote-control equipment preferably is operated by the person carrying out the measurements with the aid of the theodolite.
• the measurements are effected in the following manner.
• the theodolite 22 is positioned inside the rock chamber at an arbitrary point Pi the coordinates of which are determined exactly.
• the prism 14 is positioned in the ray path at a point P2 (see Fig. 2) the coor ⁇ dinates of which are likewise determined with great accuracy.
• the theo ⁇ dolite is set to measure the angle - * between a line 24 which extends in parallel with the non-refracted laser beam 12 and a sight line 26 which extends from the theodolite 22 to the impact point 20 of the deflected beam 16 on the rock chamber wall 18.
• the line 24 wall always extend perpendicularly to the plane in which the deflected beam 16 may occur.
• the coordinates of the impact point 20 may now be estimated in a simple manner by using well-known trigonometrical relations and on the basis of the knowledge gained of the coordinates for the measured points Pi and P2 and the read-off angle O .
• the simple situation shown in Fig. 1 the latter comprises only one horison- tal component but in the general case this angle will also comprise a vertical component.
• the area of the plane to be measured and which is perpendicular to the laser beam 12, is determined by turning the prism 14 little by little, so that the deflected beam 16 is directed against a number of points on the rock wall 18 in this plane.
• the coor ⁇ dinates of these impact points are determined with the aid of the theo ⁇ dolite 22 in the manner described above.
• a fairly accurate appro ⁇ ximation may be made regarding the cross-sectional area of the opening of the rock chamber at the position of the prism 14.
• the prism 14 When a cross-sectional area has been established in the manner indicated, the prism 14 is moved to a point P*2, which is positioned further into the interior of the rock chamber and still in the ray path of the laser beam 12.
• the coordinates of point '2 are determined.
• the beam reaches the prism 14 and is directed in the form of a deflected ray 16' (beam) towards an impact point 20' on the rock wall 18.
• the area of the plane through point P' is determined 1n the manner described in the aforegoing.
• the coordinates of points P2 and P*2 being know, it becomes easy to determine the distance between the points and thus also the planes. Thereafter the volume of the volumetric element which is delimited by the two planes may easily be determined. The wall between them is regarded as being even.
• One advantage inherent in the subject invention is that the measurement is effected manually, which means that also the choice of measuring points may be made manually.
• the measuring points are chosen so as to be representative of the cross-sectional outline, that is, minor projections, localized depressions, etcetera are avoided. This adds to the accuracy of the area calculations.
• Computer equipment (not shown) preferably is used in combination with the apparatus in accordance with the invention to process the measured values of the horizontal and vertical angles.

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• Engineering & Computer Science (AREA)
• Multimedia (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Radar, Positioning & Navigation (AREA)
• Remote Sensing (AREA)
• Length Measuring Devices By Optical Means (AREA)
• Lasers (AREA)

Applications Claiming Priority (2)

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• 1984
  • 1984-02-01 SE SE8400491A patent/SE441038B/sv not_active IP Right Cessation
• 1985
  • 1985-01-31 EP EP19850900820 patent/EP0169881A1/en not_active Withdrawn
  • 1985-01-31 WO PCT/SE1985/000047 patent/WO1985003567A1/en unknown

Non-Patent Citations (1)

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