Integrated application of geophysical methods in Earth dam monitoring

Given the mounting apprehension surrounding the recurrence of incidents involving accidents and the failure of earthen dams in the past two decades, a significant number of which can be attributed to phenomena such as seepage-induced piping and overtopping, this research was conducted utilizing non-destructive geoelectrical techniques at an earthen dam site. The primary objective was to monitor the stability of the landfill and identify potential abnormal pathways for fluid infiltration. We propose the combined application of electric resistivity tomography and induced polarization methods as indirect, non-invasive mechanisms to evaluate the structural and hydrodynamic stability of the embankment dike and its foundation. This approach complements conventional instrumentation, often referred to as auscultation, which relies on piezometric level analyses, displacement measurements, and visual inspections. A geophysical survey was conducted at an earthen dam in Rio de Janeiro, Brazil. The reservoir was specifically engineered for industrial water storage. During the study period, resistivity and chargeability measurements were systematically conducted in both rainy and dry periods, facilitating the observation of dam slope behavior under diverse climatic conditions. Consequently, we observed increased conductivity values during periods of increased humidity, and decreased chargeability values served as indicators of water saturation within the dam structure. This comprehensive data interpretation proved to be highly efficient, and the proposed methodology holds the potential for application to a wide array of landfill dams, with a particular emphasis on ore tailing dams.