The measurement of directional edge azimuth determined by gyro theodolite is referred to as gyro orientation.Due to the manufacturing defects of the overhead gyro theodolite, the gyro axis wobble balance position (called the direction of gyro meridian) observed through the eyepiece does not coincide with the true meridional plane of the passing station, so only the gyro azimuth Angle based on gyro meridian can be measured.The azimuth Angle of a gyro is obtained by measuring the difference between the direction value of the gyro meridian and the direction value of a certain side.The difference between the azimuth of a gyro and the true azimuth of a certain side (namely the dihedral Angle between the meridional plane of a gyro and the true meridional plane) is called the instrument constant.The instrument constant should be measured for each orientation;The azimuth of gyro is measured on the directional edge, and the coordinate azimuth of the directional edge is calculated.
The direction of gyro theodolite can be used: it is a horizontal direction down the hole;In the theodolite wire, the coordinate azimuth Angle of the edge of a wire is measured at intervals so as to make the wire into a directional attached wire, which can control the accumulation of angular measurement errors.Orientation of surveying for large underground projects such as mines and tunnels;Orientation of measurements in shaded areas.
When coordinate transfer is needed in vertical shaft directional measurement, a steel wire vertical line is suspended in the wellbore, and the coordinate of the steel wire is measured on the ground;The wire is measured between the vertical line of the wire and the directional edge of the gyro downhole, and the coordinates of each point of the wire are calculated according to the method of wire calculation.
The field observation of gyro direction is mainly to measure the gyro azimuth Angle of a certain side.In order to find out the coordinate azimuth Angle of a wire, a certain directional procedure must be followed.
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