Causes of deformations in vertical mine shafts in the Talnakh ore province

Mine shafts are the critical underground structures and, technologically and functionally, play an important role in the mine hoisting system. Shutdown of vertical mine shafts because of their instability, unsafety and emergency condition restrains operation of the whole mine and deteriorates its economic performance. For this reason, assessment of shaft stability and its support integrity is crucial for the sustainable and trouble-free operation of mines, and for the health and lives of mine personnel. All phases, from sinking to operation of mine shafts, involve factors which have an adverse effect on shaft support and on adjacent rock mass. The influence factors have different nature depending on the shaft sinking technology, geological conditions, flowsheet of protective pillar extraction, dynamic loads, etc. In view of a variety of causes of mine shaft damages and since deformations develop in mine shafts as a consequence of integrated impact (and symptoms of damages may be similar in case of different causes), it is necessary to carry out a comprehensive analysis in order to successively and reasonably eliminate the secondary causes and to identify the dominant causes. This study presents the analytical results on the main causes of damages of support in vertical mine shafts as a case-study of mines in the Talnakh ore province in the Norilsk industrial region. The analysis of the causes of damages in the vertical mine shaft support used a bulk of actual data, including the evidence of other agencies and the experience of the Geophysical Service of Mine Shafts at the Center for Geodynamic Safety. On the basis of the integrated analysis, the key groups of factors that influence deformation processes in mine shafts were identified. The studies show that the highest impact on the stability of mine shafts in the Talnakh ore province is exerted by industrial factors, with the dominant role of stoping operations in protection pillars. This problem is particularly acute in case of highly valuable ore bodies, when it is economically beneficial to reach maximum extraction of mineral reserves.