ANALYSIS OF LONG-TERM INSTRUMENTAL OBSERVATIONS AND PREDICTION OF EMERGENCY EVENTS AT THE SARANOVSKOYE FIELD

Abstract

The monitoring of the rock mass displacement at the
Saranovskoye chrome ore deposit has been carried out
for many years. Based on the results of the surveying
observations, the regularities of the rock movements
were analyzed to identify possible forerunners of the
emergency development of deformation processes manifesting in sinkholes of the earth surface. The distinctive feature of this study is that one of the series of instrumental observations was made shortly before the collapse of the earth surface over the unfilled voids of previously mined blocks. It has been discovered that the study area had experienced vertical shifts of alternating nature within several years, with a rise of the earth surface immediately preceding the collapse. However, in the course of further studies the local zone of accumulation of rock mass subsidence with gradually increasing speed was identified, which occurred several years before the sinkhole appearance directly above the site of its formation. The
absence of this zone in the period preceding the collapse
is explained by the destruction of the observation benchmarks in this local area. Variable annual changes in the surface elevation are most likely coused by the geodynamic movements of the active geological structure associated with the deposit, which has been activated because of years of mining activity. The analysis results thus revealed that under certain mining and geological conditions destructive deformation processes can develop extremely localized with no visible signs of impact on the adjacent rock mass and the earth surface, which should be taken into account when developing geomechanical monitoring projects at the deposits.