Investigation of the occurrence of intensive seismic activity at the “Polkowice-Sieroszowice” copper ore mine, Poland

A series of intense seismic activities were unusually reported during the initial stage of room and pillar mining operations at the “Polkowice-Sieroszowice” copper ore mine, in Poland. In fact, high-energy tremors with energy of up to 107 J were observed in many mining fields from the beginning of the mining operation to the moment before reaching the critical space of the caved zone (goaf). Some of these tremors caused floor heave, sidewall squeezing, and spalling of the roof and sidewalls in the workings, leading to the stoppage of mining operations. This paper aims to identify the possible causes of these unexpected tremors. For this purpose, the geo-mining conditions and seismic activity data from the studied mining fields were reviewed and analysed. Additionally, a numerical analysis of rock mass behaviour was conducted, considering various geomechanical factors to better understand the mechanisms of seismic activity in these fields. All numerical calculations were performed using the finite difference method (FDM) code, FLAC3D. Based on the findings, the major causes of the high-energy tremors were determined as high primary stress, high-strength roof rocks, and the presence of a thick salt layer in the roof rocks. Consequently, practical recommendations for future mining operations were suggested to mitigate the impact of intense seismic activity. This research is expected to provide a valuable reference for copper mines prone to tremors and rockbursts, not only in Poland but worldwide.

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Opracowanie rekordu ze środków MNiSW, umowa nr POPUL/SP/0154/2024/02 w ramach programu "Społeczna odpowiedzialność nauki II" - moduł: Popularyzacja nauki (2025)