Obtaining geotechnical parameters from correlations between geophysics and CPT tests in tailings dams

Abstract

This article introduces a hassle-free methodology for geotechnical parameters to be obtained from correlations between geophysics and CPT field tests in tailings dams undergoing the decommissioning process, which are reasonably representative of site conditions, from the very early project stages, with extensive coverage of all impoundment parts, without the requirement for large-size drilling programs. The development methodology consists of running direct (CPT) and indirect (geophysics) tests within the same area of the tailings dam to be decommissioned, with information crosschecking, thus allowing for results to be presented as adjustment equations, capable of describing tailings undrained shear strength based on geophysical survey data. A dam within the region known as Iron Quadrangle, in the state of Minas Gerais, Brazil, was selected to pilot the tests. The results obtained showed consistent adjustments, thus validating the proposed methodology as a complementary geotechnical investigation tool, and also enabling an optimized investigation plan to be proposed for similar tailings dams undergoing a mining process, so as to provide better assessment of the safety conditions of the proposals for deactivation with reduced schedule and resource savings.