During the development and construction stage of the crusher chamber of Dacita Project at El Teniente mine, instabilities such as rock fall due to the looseness of rock mass confinement took place mainly in zones with singular geometries. With the purpose of evaluating the deviations that the design implementation could have, geomechanics monitoring plan considered several topographical tri-dimensional measurements with a laser scanner, using LiDAR technology, obtaining as-built geometries with a millimetric precision, which were later processed in order to analyze statistical differences in time, in other words, to monitor deformation fields in large scale. This information also represented an opportunity to develop local calibrations for the tri-dimensional numerical models built on the feasibility stage. Stress tensors were calculated on each point of the cloud obtained by LiDAR; then, results were filtered, considering all the points with lower scatter, orientations of the principal stresses and magnitudes of the mean stress, discarding points outside the preferential clusters. Two different populations of data were recognized, depending on the depth of the overbreak compared to the geometry of the design. Finally, results obtained from the back-analysis allowed corroborating the initial design considerations and the consolidation of the background information necessary for future requirements.
1.1. El Teniente Mine overview
El Teniente Mine is a Codelco Chile underground copper mine. It is located in the Andes range in the central zone of Chile, about 70 km SSE from the capital city, Santiago. El Teniente is the largest known copper– molybdenum deposit in the world. It is hosted in a copper porphyry system. The main rock types include Andesites, Diorites and Hydrothermal Breccias of the Miocene era. Since 1906, more than 1100 million tons of ore have been mined. The mine is currently extracting around 140,000 tons/day using mechanized caving methods. Advanced and post-undercut panel caving methods, variations of the standard block caving, were introduced in 1982 and 1994, respectively to exploit primary copper ore.