Changes in the physical and mechanical properties and structure of rocks depending on the depth of mining operations in iron ore quarries

The trend of the activity of open-quarry mining enterprises of iron ore raw materials is an increase in depth quarries. It is investigated in the work, changes in physical and mechanical properties and rock structure depending on the depth of mining operations in quarries. Natural geophysical and laboratory methods of research were applied. It was established that the angle of internal friction, Poisson’s ratio and rock density practically do not depend on depth of mining operations. But with an increase in the depth of iron ore quarries, there is an increase in the compressive and tensile strength of rocks. Indicator of specific adhesion has significant dynamics of fluctuations depending on the mineral composition of rocks and can either increase or decrease in deep horizons, which must be taken into account in each specific calculation. For example, by determining marginal angles of slopes of sides and ledges. According to the data of geophysical studies, it is established a characteristic increase in the intensity of creep shear processes and surface deformations rocks when the quarry depth increases. The results of research are recommended to be taken into account when organizing the mining and technological process in deep iron ore quarries.