Effect of blast-induced vibrations on fill failure in vertical block mining with delayed backfill

Numerical modelling has long been used as a powerful tool for geomechanics mine design and analysis of such problems as ore dilution. Open stoping mining method with delayed backfill is generally employed for mining steeply dipping tabular ore deposits. Several authors reported that consideration of production blast vibrations on adjacent, exposed backfill faces is crucial for the effective backfill design for minimum ore dilution due to fill failure. In this study, it is shown that blast vibrations can be characterized with dynamic numerical modelling. A FLAC^3D dynamic numerical model has been developed for a typical layout of a secondary stope that is being mined next to a previously mined and backfilled primary stope. The numerical simulations are validated by comparing predicted failure geometry with laser-surveyed stope profiles obtained with a cavity monitoring system. It is shown that blast-induced vibrations can be a primary cause for wedge-type failure of the backfill face.