Evaluation of fault-slip potential in underground mines

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It is not uncommon that geological structures such as faults and shear zones are found in underground hard rock mines in Canada. In the case that faults are located close to active mining areas, the extraction of ore could cause the fault to suddenly move thus creating strong seismic waves across the mine. This event is known as fault-slip and the seismic waves generated by it could result in severe damage to nearby mine openings and even personnel injuries. The goal of this project is to develop advanced computer models that adequately describe the fault-slip phenomenon observed in underground mines. Based on these models, simple equations will be derived to help the engineer estimate the additional rock reinforcement required to sustain imminent fault-slip, and to plan the stope extraction schedule in the most efficient way. In order to do that, a case study mine is selected. This is the Garson mine of Vale - Sudbury Operations. The mine has been in production for more than 100 years and mining is currently being done at a depth of 1.5 km. Garson mine is known for its complex geological structures and with the increase of mining depth to 1.5 km in recent years, the microseismic activities in the mine have increased and a number of rockbursts have been recorded. The first step in this research is to gather all the relevant data of the rock materials found in the mine. Particular attention will be paid to the interpretation of past microseismic records with respect to mining activities. A number of 3-dimensional advanced computer models will be developed to simulate the mine stopes and surrounding geological structures including faults. After comparison of model results with seismic records, the best computer model will be identified and retained. With the help of the selected computer model, a wide range of numerical results will be generated and analysed statistically to derive simple equations describing the relation between the fault properties and seismic parameters. This process is known as regression analysis. The relationships obtained from the regression analysis can serve as practical mine safety tools to predict the occurrence of fault-slip and help estimate the damage by seismic waves arising from fault-slip.