ROCKMASS DEFORMATIONS CAUSED BY ZINC AND LEAD ORES MINING IN THE OLKUSZ REGION (SOUTHERN POLAND)

 Jerzy Cabala, Leslaw Teper and Tadeusz Rutkowski

 University of Silesia, Faculty of Earth Sciences, Bedzinska 60, PL 41-200 Sosnowiec, Poland, E-mail: cabala@us.edu.pl / teper@us.edu.pl,  Fax +48-32-2915865

 

Abstract: Results of study on continuous and discontinuous deformation are presented. Ground surface deformations formed in 1980-2002 period. Conical potholes, depressions, cracks, as well as edges like scarps and ridges have been observed. The depth of some structures reached 25 metres and their areal dimension achieved ca. 500 square metres. Continuous deformations might form as sag structures with subsidence ranging from 500 to 600 mm. The deformations were frequently filled up with Quaternary sands from the cover. A model of the deformation development has been adopted, which helped predict subsidence parameters for the part of the "Klucze" orefield scheduled to open in the future. Mining has influenced changes of physical features of the Triassic complex in the close vicinity of excavations. In this region, influence of groundwater drainage on the rockmass state is of the major importance. Knowledge of the deformation growth comes in useful to correct building development and to recognise the occurrence of new hydraulic connections of the Quaternary water horizon with the Triassic aquifer. Reclamation of post-mining areas will be particularly important after closing the last operating zinc and lead mine in this region what is expected in a few years.

 

Keywords: sinkhole, discontinuous ground deformation, subsidence trough, continuous ground deformation, subsidence prediction, Zn-Pb ores, Silesian-Cracovian district