ABSTRACT
The prevention from landslides and failures due to slope instability remains one of the main problems in open mining. Determination of the critical strain values of the rock mass adjacent to an open pit is important for studying the processes causing slope instability. Hard rock massifs are characterized by small strain values before failure because the rocks are very strong and can withstand the stresses to a critical level for a long time, exceeding which a dynamic failure occurs, caused by their fragility. The movement of different size rock blocks in deposits mined is associated with influence of constantly changing mining-induced and natural factors. As a case study object, the authors have chosen the Zhelezny open pit mine, located in the Kovdor rock massif, the Kola Peninsula. In order to determine the strain values, the authors apply traditional geodetic and satellite geodesy methods. The authors have summarized experience in measuring strains in hard rock massifs during open-pit mining and developed methodological recommendations to monitor open pit slopes by satellite methods. The recommendations contain the issues of choosing a location and construction of reference points, performing satellite measurements and preliminary and final data processing. According to the recommendations, geomechanical monitoring should be an integrated system for obtaining data on the properties and stress-strain state for various hierarchical structural levels of the hard rock mass. So, it is reasonable to use various measurement methods. In this case, the obtained data allows providing for the safety of mining operations, including the slope stability forecast.
