A geotechnical evaluation of the Cumba Pit Slope Failure, Dominican Republic

Abstract

Abstract The combined availability of topographical, geological, structural, hydrogeological and monitoring data is rapidly increasing. Technology and software advances allow the real time incorporation of this data across various software platforms. This paper describes the back-analysis of a 70 m high, pit slope failure of an open pit gold mine in the Dominican Republic, using data from aerial photogrammetry, ground-based synthetic aperture radar and 3D limit equilibrium and finite element modelling. This back-analysis process is considered leading practice with the latest technology. The (northern) side of the Cumba pit slumped along a non-daylighting plane that was identified after the failure event. Remedial investigations included review of geological data, major structures, rock mass constitutive models and groundwater conditions. Topographical and structural data acquired from aerial photogrammetry, pre- and post-failure event, was input into 3D models to replicate observed ground movement. 3D models of pit progression were compared with displacements recorded by ground-based synthetic aperture radar to calibrate model inputs and increase reliability of forward predictions. Such a technical review was completed in less than one week, and the review process implemented for the Cumba pit slope failure now forms the baseline approach for all future geotechnical analysis at the operating mine.