Assessment of the Condition of the Foundations of a Building in a Mining Operations Area at Risk of Sinkholes—A Case Study

Sinkholes caused by historical underground mining operations are significant geotechnical and safety hazards for new residential developments. This paper presents a case study concerning the assessment of the condition of the foundations of a planned multi-family residential building located within a former mining operations area in southern Poland, which is exposed to the risk of discontinuous ground deformation. This study aimed to identify potential voids within the rock mass and develop safe structural solutions for building foundations. To this end, a comprehensive site investigation was conducted, including two-dimensional electrical resistivity profiling to detect zones of high-resistivity anomalies. High-resistivity anomalies were identified beneath several building segments, suggesting the presence of voids or loose soil resulting from shallow coalmining operations. Based on these findings, a finite element analysis (FEA) of the reinforced concrete foundation slab was performed to simulate the presence of subsurface cavities. The results indicated local tensile stress in the slab of up to 0.34 MPa, which necessitated subsequent design adjustments. Consequently, the use of additional bottom reinforcement and continuous reinforced concrete ribs was proposed to enhance structural safety. This study highlights the necessity of detailed geotechnical and geophysical analyses of planned development zones located in former mining operation areas to address the risks related to sinkholes and ensure the long-term safety of new buildings.