For the development of the pre-feasibility study for the New Mine Level Project (NML) carried out by Codelco Chile Project Corporate Vice-Presidency, it is fundamental to have numerical models that allow estimating the stress state for the various mining options under study in a quick, simple and reliable manner. For this reason, a simplified mine scale model was created to analyse geomechanical issues that go from drift scale (overbreaking), large excavations (caverns) to mine scale issues (caving front geometries, mining macro-sequences, sector interactions). The software tool preferred was Map3D (Mine Modelling Pty Ltd).The boundary conditions used as the base for the Map3D modelling tool correspond to the geometry to be analysed and the pre-mining stress state in the zone of interest. To estimate this latter condition, the Conceptual Stress Model (Karzulovic et al., 2006) information was used and originally, the stress orientation expected for that zone based on Plate Tectonics (east-west trending) was considered. To test the model's efficacy, various validation exercises were carried out: comparison of the model's results with field stress measurement for different years, between the abutment stress zone predicted by the model and the one observed in the field, and the model-predicted overbreak versus the actual overbreak obtained through field surveys.It can be concluded that the model created fulfils the reliability levels that have been historically used for mine-scale models in a pre-feasibility engineering stage. The validated and calibrated boundary conditions can be applied both for mine-scale and drift-scale models, with error values of 40% compared to stress measurements and 20% when compared to field-observed damage.

Over the last several decades, mine-induced seismicity has created serious safety and production issues for underground mines worldwide. A significant proportion of the large seismic events resulting in rockbursts have been related to a 'fault slip' mechanism on shear zones. This source mechanism has been the subject of a number of numerical modelling studies in the past and several techniques have been developed to analyse it, but these methods are highly dependent on the strength properties used to simulate (explicitly or implicitly) the non linear response of the rock mass. A methodology is proposed in this paper to estimate non linear ride without considering explicitly the strength properties of the shear zones, considering the premining Limit Equilibrium Strength (LES). As a result of this methodology, observed seismic trends can be reproduced through numerical modelling and if enough data exists to calibrate the model, accurate magnitudes of seismic moment can be reliably forecasted.

Reservas Norte (RENO) is one of the panel caving sectors of El Teniente mines, owned by Codelco Chile. The sector has experienced mine-induced seismicity for many years. The work presented in this paper focusses on seismic activity recorded between the period from January 2004 to July 2008. The interpretation of the seismic data revealed that the sources of elevated seismic hazard (large events) at RENO during this period could be attributed to four major geological structures: Falla G, Falla F, Falla C, Falla N1. In particular, the seismic response of the four structures to undercut blasting activities is examined in detail.The use of numerical modelling has shown that it is possible to simulate this response after calibrating the model against the cumulative seismic moment released by the faults, as mining advances towards them. This calibrated numerical model can then be used to forecast future seismic responses. The main product of this work is a tool that can be used to rank different undercutting rates and geometries in terms of seismic hazard.

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Crown pillar in cave mines corresponds to the solid rock pillar located between the cave and the surface in the early stages of the caving process. A correct estimation of the failure time may provide valuable assistance in planning underground and surface activities.While modelling has shown important advances in the simulation of the breakthrough process, empirical tools may provide an early warning of the pillar failure process, delivering early guidelines about when to isolate surface infrastructure or change draw velocities due to the change in the mined column height. This paper reviews empirical methods to estimate crown pillar stability and their application in the breakthrough process in block cave mines, evidenced by a case study in Chuquicamata underground mine.