PROBLEM OF ASSESSMENT OF THE SAFETY FACTOR OF THE OPEN-PIT SIDES

Abstract

According to normative documents for definition and justification of parameters of pit sides and benches a calculation of safety factor by means of classical methods of extreme balance has been made. The article presents the results of the researches of slope stability of the Kiyembayevsky open-pit where the collapse of the benches on the western side had occurred. For identification of the causes of the collapsing and for calculation of stability the updating of physic-and-mechanical properties of the rocks composing the massif was made. On the basis of the obtained data calculation of the safety factor (SF) for the
actual contour of a pit has been executed. It has been revealed that actual state of the sides and benches of the pit differs from results of calculations. Thus, not the low strength properties of the massif, but the formation of the extended cracks of shift character caused by processes of deformation in the conditions of the increased compression in one direction and the increased depression in the another direction with deformation of primary structure of the massif of rocks is the main cause for distortion. The SF values received by various methods (Fedorovsky-Kurillo, Bishop, Fillenius, Yanbu) differ from each other
within 10 – 15%. For safety of conducting mining operations taking into account geomechanical conditions of the off-working of the Kiyembayevsky pit, the design of observing station has been developed for monitoring of deformation processes of the adjacent rock mass. It includes two traditional profile lines and two local observing stations. Observations of the current condition of the massif not always give the chance to prevent collapses and landslides, but allow to reduce possible damage from them and especially risk for the people who are in career.