Geomechanical assessment of the stability of internal dump on worked up foundation of the open pit edge

Abstract

Purpose. Evaluation of the stability of the internal rock dump on the worked up pit edge of Pervomaiskiy quarry of SevGOK taking into consideration geometry, rock physical and mechanical properties and seismic impacts from blasting operations. Methodology. To study geomechanical stability of the pit edge while mining operations, the data of engineering and geological surveys, technological schemes for conducting open mining operations, surveying data were used. For numerical simulation of the internal dump slope stability and the pit edge slope stability, the finite element analysis software Phase2 by Rocscience Inc. is used. Findings. Geomechanical assessment of the stability of the quarry internal dump constructed on the southwestern pit edge taking into consideration complex structure, rock properties and seismic effects from blasting operations has been carried out. For a three-tier dump, safety factors were calculated taking into consideration seismic impacts from blasting operations at a quarry in the range of 0.00625-0.1 g, which corresponds to a magnitude of 3-7 earthquake. The potential effect of extinguished underground mine workings on the stability of the internal dump was assessed. Originality. It is established that the maximum potential displacement of the massif near the extinguished underground workings in the pit edge reaches the value Uxy = 7.6-22.0 m, and a large-scale subsidence area of rocks up to 50-60 m in diameter and up to 4 m in depth can form on the surface of the internal dump. Seismic impacts from blasing operation at the quarry can be as a trigger factor for geomechanical disturbances. Practical value. The results of numerical simulation of the stability of internal dump on worked up the pit edge foundation can be considered in mining development projects to ensure the safety of the open mining technology and internal dumping operations.