Monitoring of seismic activity during mining in the Upper Silesian Coal Basin is a part of rockburst prevention system. System is composed from two parts – seismological (SL) and seismoacoustic (SA) monitoring. Evaluation of data from both systems allows describing stress deformation process during mining and evaluation of rockburst mitigation techniques effectiveness. Described longwall was mining in a protective pillar after two trial room and pillar (R&P) testing panels were completed.
Evaluation of seismic activity was carried out by special software tool which allows simulating daily advance of mining and registered seismic activity. Different mining stages were identified for evaluation of seismic activity (e.g. weekly and daily summary graph of seismic activity, Benioff graph, event rate graph, energy vs time graph etc.). Evaluation of seismic activity provides many interesting results, mainly in the area of longwall panel termination when one pillar of the R&P trial was impacted by the longwall. This work presents seismic activity analysis, detailed site conditions and implemented active rockburst measures and its effectiveness. Analysis of seismic activity allows to formulate conclusions for longwall mining operations and evaluation of seismic activity in unfavourable geomechanical conditions within the area of protective shaft pillar border.
Coal mining is still one of the most dangerous branches of all working environments. Seismic events induced by coal mining has been a common occurrence in the Czech Republic [1] as well as in Poland e.g. [2] because mining regions in the Czech Republic and Poland represent one coal basin (Upper Silesian Coal Basin – USCB). One of the most useful ways to observe or predict induced seismicity within the rock mass in which mining operations are situated is to monitor the seismic activity in the demarcated area [3]. It is essential to identify part of the rock mass where there is a large number of high-energy tremors, or the part with a specific local accumulation of low- and high-energy seismic events [4]. Mining of previously untouched pillars (protective shaft pillars, protective crosscut pillars, etc.) is dangerous due to complicated stress filed development in protective pillars due to long term mining in their vicinity. With the knowledge of the local conditions and to ensure the safety of the workers and mining technology, a seismic monitoring system was suggested as one of the main preventive methods. Seismic activity due to longwall mining in the border of protective shaft pillar, where R&P mining method was tested in the last two years, is the main goal of this paper. Induced seismicity was evaluated including seismic activity due to longwall impact of pillars developed by R&P method by advancing the longwall face. An explanation of the used mining terms which could be not known in rock mechanics can be found in e.g. [5].