An Attempt at Evaluation of the Remnant Influence On the Occurrence of Seismic Phenomena in a Room-and-Pillar Mining System with Roof Deflection

Experience gained until now underground mining worldwide and in Poland indicates that remnants may have an impact on the occurrence of seismic phenomena. Remnants are stress concentration sites encompassing both the deposit and the layers of rock mass located above and below the undisturbed rock. In the case where stresses in the remnant exceed its strength, it may collapse, and under unfavourable geomechanical conditions, stress-induced rockburst may occur. Remnants may also cause breaking of strong roof layers above their edges, which results in the occurrence of high-energy shocks (Salustowicz [30], Adach [3], Adach and Butra [4]). This article presents the possibility of utilizing numerical modeling to evaluate the influence of remnant upon the occurrence of seismic phenomena. The results of numerical calculations performed for a model room-and-pillar mining system with roof deflection under the conditions of copper ore mines in the Legnica-Głogów Copper District (LGOM) are presented. Numerical calculations in a plane strain state were performed by means of Phase2 v. 8.0 software for the analyzed mining system in which remnant was left behind. The results of numerical modeling showed that sudden fracturing of roof layers above the mined out space may occur on the edge of the remnant. This may cause a shock with very high energy, and under the appropriate conditions, this may lead to the rockburst phenomenon.