Using Surface Geophysical Methods to Detect Voids in the Near-surface Zone

Abstract

This study investigates the physical and mechanical properties of rock formations using seismic velocity profiling and electrical resistivity methods to identify structural anomalies such as voids, fractures, and geological composition changes. Conducted in four test wells in southern Poland, the analysis emphasizes the practical applications of these geophysical techniques in engineering, mining, and environmental protection.

Seismic velocity profiling measured wave propagation, while electrical resistivity assessed rock resistance variability, aiding subsurface zoning. The methodology involved designing depth cuts for resistivity based on seismic profiling results, identifying weak materials, and establishing critical geomechanical boundaries. Results indicated varied seismic velocities and resistivity distributions with depth, revealing potential geological disturbances. Measurements were conducted radially around wells, highlighting resistivity anomalies that signify risks related to subsurface void migration and changes in geomechanical properties.

The analysis confirmed a general trend of increasing seismic velocity with depth, with significant deviations suggesting differences in rock quality. Resistivity measurements identified anomalous zones, indicating potential voids or changes in rock composition. These findings are crucial for planning safe earthworks, soil stabilization, and environmental monitoring, particularly in subsidence-prone areas. Future research may enhance anomaly detection and monitor changes in rock mass properties over time.

Combining seismic velocity profiling and resistivity measurements proves effective in identifying subsurface structures, which is vital for risk mitigation in engineering and environmental projects.