In post-mining areas where hard coal mining took place under a thick overburden of carbonate rocks, there are often geomechanical threats occurring to the designed and existing buildings. They manifest by the occurrence of post-mining voids and deformations created in the Carboniferous layers and related to erosive processes, including karst ones occurring in the rock environment carbonate. Various geophysical research methods, including electrical resistivity imaging, find application in the assessment of deformations in the rock mass. Geophysical surveys may be applied to assess the necessity of carrying out treatment and protection works, e.g., borehole injection and determination of the boreholes‘ number and location. The paper presents two case studies of geophysical surveys using the method of two-level electrical resistivity profiling (ERP) and electrical resistivity tomography (ERT) in two adjacent research areas with a similar geological structure and a similar scope of mining operations. Based on the analysis of the obtained results, injection of voids and zones of a loosened ground in both areas was designed and executed. The analyzed cases have shown that methods of geophysical ground investigation based on electrical resistivity imaging provide accurate forecasting of the bedrock structure and can be used in practice to reliable determination of the threats to the ground surface from discontinuous deformations and their successful elimination.
The authors of this article performed the following research and their interpretation independently. They have appropriate geological and geophysical qualifications and many years of practical experience. The above allowed us to present in this article the issue, the need to select and the course of geoengineering procedures in areas where, on the one hand, shallow mining operations were conducted, and on the other hand, the presence of complex geological conditions (karst phenomena) was found.