Verification of Dynamic Behavior Modeling of Las Tórtolas Main Dam during 27F Chile Earthquake

摘要

Currently, the use of numerical dynamic analysis modeling for estimation of deformations in tailings deposits dams has increased, particularly in Chile in accordance with the requirements of country?s regulations (D.S. N° 248). Considering the relevance that these analyses have achieved, it is necessary to validate these models comparing their results with real measurements obtained for large earthquakes that have occurred in Chile in recent years. Because of this, the present study performs a three-dimensional dynamic analysis, using FLAC3D? software, of the main dam of Las Tórtolas tailings deposit, constructed with cycloned sand and located in the central zone of Chile, 45 km north from Santiago. Analysis was carried out for the geometry that presented the dam during the earthquake of February 27~(th), 2010 (27F Chile), magnitude Mw = 8.8 with its epicenter 360 km from the deposit. In the development of this study, information obtained from the geotechnical instrumentation that was operative at the time of the earthquake was used. Sands that constitute the dam were characterized by an extensive program of laboratory tests, which included among others: Consolidated Drained triaxial (CID), Consolidated Undrained (CIU and anisotropic), cyclic, small deformations triaxial and consolidation tests. To represent the behavior of this material an elasto-plastic constitutive model with a Mohr-Coulomb type failure criteria was used.At the date of the earthquake, the geotechnical instrumentation of dam included Casagrande piezometers, fiber optic piezometers and accelerometers, which allowed registering the seismic acceleration to which the dam was subjected and the variations of water table during the event.Residual post-earthquake deformations obtained by the model are compared with those induced by 27F Chile earthquake observed in the field.