North-Eastern State University, Magadan, Russia

V. V. Arno, Associate Professor, Candidate of Engineering Sciences, vvnika@mail.ru

Underground mining widely exercises counter heading of horizontal and inclined underground openings. In this regard, it is critical to minimize the error of connection of counter faces. The connection accuracy directly governs the rate of mining, safety of miners and the cost of extra adjustments. Preliminary calculation of the error and estimated accuracy in connection of counter faces is an integral part of a mining plan. The pre-calculation takes into account many factors: geological conditions, method of face cut, precision of measuring equipment and qualifications of personnel. The calculation uses the statistical and analytical methods. The statistical method involves processing of the result obtained after numerous measurements carried out in the similar conditions earlier, which allows a probabilistic error assessment. The analytical method takes in mathematical modeling including all known parameters, and numerical modeling to determine possible departures. In quasi trilateration which consists in measurement of angles and distances between points, it is possible to minimize the allowable error owing to laser equipment and advanced electronic tachometers. The integrated approach of the error pre-calculation includes both the mathematical analyses and practical techniques, for instance, test drilling to evaluate the real-life geological situation, which, finally, contributes to the higher accuracy of connection of counter faces. The article describes estimation of accuracy in connection of counter faces as a case-study of ventilation channel no. 3 on the Level of 500 m at the Kubaka deposit. It is illustrated that setting of a position and heading direction for an underground opening is a common task in surveying, and, though there are different variants of setting positions of mouths of underground openings and specifying their directions, the original principle is the base. It is found that the quality of surveying and surveillance stands out amongst the main determinants that influence accuracy of connection of counter faces.
The author expresses her thanks to the Director of Gorgeopro LLC A. M. Volin for the help and consulting.

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