Underground surveying

An underground survey is based on precisely the same principles as the geodetic one on the surface. The methods of reading angles and measuring distances, of computing azimuths, bearings, latitudes and departures, coordinates, and elevations, and of plotting the results are alike in all essentials. In their practical details, however, a number of differences are introduced by certain peculiar conditions under which a mine survey has to be conducted. These conditions are: 1. working in the dark requires that both the point to be sighted and the cross-hairs of a telescope must be illuminated. 2. working in constricted places and in passages through which traffic must not be interrupted often requires the use of special devices for mounting the instrument. 3. stations must be placed on the roof when possible to assure their permanence and visibility. 4. steeply inclined sights are more prevalent requiring that a transit shall be always in perfect adjustment. With very steep sights an auxiliary telescope is required involving a correction in the reading of angles. 5. a higher degree of accuracy is usually required than in ordinary land surveying. It frequently happens that a complete circuit cannot be made, whereby the error of closure can be determined and distributed, or a mistake located and corrected; hence careful work by refined methods is the only assuran< of accuracy, 6. Shaft plumbing is a special problem peculiar to the underground surveying.

Дата добавления: 2015-07-19