Seismic Activity and Convergence in Deep Mining Field, Case Study from Copper Ore Mine, SW Poland

Abstract

The copper ore deposit in SW Poland has been excavated for about fifty years by three deep mines owned by the KGHM Polish Copper JSC. Seismic activity and rock-bursts have been accompanying mining operations since the mines were launched. Therefore prevention measures have to be implemented to assess, mitigate and reduce the seismic and rock burst hazards. Seismic activity i.e. the energy and number of tremors is monitored permanently by means of the mine seismological network. The seismic hazard is also controlled with measurements of the convergence of mine workings. The results of the convergence and seismic activity measurements allow for continuous monitoring of rock mass behavior, as they may indicate increased energy accumulation in the rock mass. On this basis, procedures provoking the release of excess energy from the rock mass can be performed, which may limit the occurrence of uncontrolled, and therefore dangerous to people seismic phenomena. This threat results, among others, from the deposit geological structure and tectonics as well as the significant depth of exploitation. The necessity to carry out measurements for assessing the state of the rock mass is stated in legal regulations and internal mine ordinances. The purpose of the paper was to analyze and assess the relationship between the convergence and seismic activity. The investigation covered one mining panel in the Polkowice-Sieroszowice mine and the four-year period.