68th Canadian Geotechnical Conference and 7th Canadian Permafrost Conference

DETERMINING STABLE SPANS OF UNDERCUT CEMENTED PASTE BACKFILL

Session: Mining Geotechnique II / Géotechnique minière II

Murray Grabinsky, University of Toronto (Canada)
Amin Jafari, University of Toronto (Canada)

A significant underground mine design challenge is predicting the stability of a previously placed cemented backfill when it is to be undercut in a subsequent stage of mining. Mitchell (1991) proposed several limit equilibrium analyses for this design situation based on different assumed modes of failure, but little has been done since then to more carefully consider the most appropriate means analysis approach. This paper considers a tentative framework for an alternate limit equilibrium solution, based on the assumption that the cemented backfill behaves as rigid struts to support the overlying fill. The advantage of this analysis approach is that it provides a unifying model for the previous disparate analysis methods. Remaining challenges to using this analysis for practical design will be addressed.