Zastosowanie badań tektonicznych w górnictwie odkrywkowym na przykładzie kamieniołomu Braszowice

Abstract

  Określono przebieg i udział ilościowy głównych kierunków spękań i stref tektonicznych. Ze względu na zróżnicowany wpływ spękań na stateczność ścian kamieniołomu w zależności od zasięgu powierzchni nieciągłości i kątów nachylenia wydzielono trzy grupy spękań. Ujawnienie podstawowych cech anizotropii strukturalnej masywu gabrowego pozwoliło na wyznaczenie najkorzystniejszej orientacji ścian eksploatacyjnych w kamieniołomie. Poza aspektem praktycznym badania umożliwiły poznanie niektórych prawidłowości tektoniki masywu gabrowego. THE USE OF TECTONIC DATA IN OPEN-STRIP MINING AT THE EXAMPLE OF THEBRASZOWICE QUARRY Tectonic data have appeared to be of marked value for appropriate selection of exploitation front in open-strip mining and reduction of hazard in the works, which results in increase of demand for tectonic surveys. In the Braszowice gabbro quarry near Ząbkowice Śląskie (Figs. 1, 2), there were taken measurements of spatial orientation, spacing, extent and morphology of fractures. The obtained results were plotted in rose (Figs. 3, 5) and other diagrams (Figs. 4, 6), graphs of angle of dip (Fig. 8) and tabulated (Table I). There were taken 437 measurements so the obtained results may be regarded as sufficiently representative.The pattern of fractures in rocks appears highly complex when analysed in the scale of the whole quarry as well as in individual walls (Fig. 2, Table I). There may be differentiated six directions, grouped in assemblages oriented normal to one another. On the basis of geometric premises, the following pairs of directions have been differentiated: WNW-ESE and NNE-SSW, NW-SE and NE SW, and NNW-SSE and W-E.Moreover, three groups of fractures have been differentiated with reference to block separateness in rock massif and not their orientation. First of these groups comprises vertical to steep dipping fissures and tectonic zones which cut quarry walls throughout their height. The WNW-ESE and NW-SE directions predominate in this group and the forms represent tectonic elements best displayed in this quarry.The second group comprises fractures usually NE-SW oriented and dipping eastwards at low angles, from 30 to 60°. Discontinuities of that type are rather innumerous but, nevertheless, they bear a negative effect on stability of western walls in the quarry.The third group comprises minor fractures, up to a few meters long and representing all the directions recorded here. The fractures are responsible for block separateness in the rock massif and, therefore, for local unstability of walls or their parts.The crossing of the low-angle discontinuities and those of individual systems of vertical ones (WNW-ESE or NW-SE oriented) and of discontinuities belonging to the latter systems is important from the point of view of open-strip mining practice. It usually leads to origin of rock wedges and falls of such wedges from rock face, creating serious hazard for miners.The studies showed that the mining works will be safer and at the same time conducted under morefavourable conditions when they are mainly carried out to the north-east, in azimuth varying from 15 to 45°. Conditions prevailing in western walls of the quarry were found to be the least favourable so these walls should not be subjected to exploitation.