Study of Rock Mass Stability Decrease due to Underground Mining

Abstract

The optimization of underground mining processes is carried out based on rational use of energy for obtaining preset broken ore size. The effective optimization requires correct assessment of the properties of the rock mass to be broken. Energy management requires assessment of rock mass stability decrease due to impact of natural and technogenic stresses. To make adjustments to the general energy management model, information on the rock mass structure is required to be obtained by geophysical methods. To optimize broken rock/ore size (to minimize oversized or excessively crushed mineral fraction yield during breaking), blasting energy application should be regulated and smart. The study is aimed at assessing the effectiveness of using geophysical methods for the prompt and correct assessment of rock and backfill mass condition during underground mining of mineral deposits. Decreasing stability of rock masses is assessed using the method of electrometric surveys in noncore exploratory boreholes. Rock mass stability study allowed revealing correlation and dependencies between the studied parameters. Effectiveness of using geophysical methods for differentiating natural and technogenic masses by degree of decreasing their stability due to geological and technogenic stresses. To determine the coefficient of decreasing rock mass stability based on rock apparent resistivity data, electrometric logging was used. This allowed to differentiate rock mass by the degree of decreasing rock mass stability based on the revealed dependency. The features of the geophysical survey components are described in details. The methodology and findings of the underground electric sounding using a sequential gradient electrode system at specific metal deposit are presented, including using theoretical curves and determining rock conductivity and the distance to workings. Besides, correctness of the geophysical method findings was assessed differentially. The assessment was prepared for decreasing rock mass stability based on electrometric logging data, and for advance outlining heterogeneity zones in rock masses by electric sounding along working walls. Based on findings of the conducted experimental work on revealing structural boundaries within rock mass, the method of electric sounding along working walls was recommended for application in practice. As for the studied borehole electric sounding application, the convergence of the experimental and theoretical curves is insufficient to recommend the method for practical application.

Keywords

• deposit development
• rock
• decreasing stability
• geophysical methods
• electrometry
• resistivity sounding