68th Canadian Geotechnical Conference and 7th Canadian Permafrost Conference

MINE BACKFILL PORE WATER PRESSURE DISSIPATION: NUMERICAL PREDICTIONS AND FIELD MEASUREMENTS

Session: Mining Geotechnique II / Géotechnique minière II

Mohammad Shahsavari, University of Toronto (Canada)
Murray Grabinsky, University of Toronto (Canada)

Cemented paste backfill (CPB) has gained popularity in underground mining operations over the past decade. Fresh CPB is being held in the stope by a barricade until it cures and is self-supportive. Therefore, the barricade safety is crucial in mining industry. The pressure acting on the barricade is dependent on the pore water pressure within the CPB. The problem of self-weight consolidation of an accreting material was first studied by Gibson (1958). Fahey et al. (2010) applied Gibson’s solution to the consolidation of CPB and introduced lower and upper bound solutions. Shahsavari and Grabinsky (2014), based on the in-situ measurements, introduced a new boundary condition and studied its effect on the pore pressure variations with time. However, the effect of the slurry layer weight on the pore pressure was not considered. In the current study, the stresses due to the presence of a slurry layer in addition to the hydraulic boundary condition are considered in the analysis. The process of consolidation is modeled in FLAC3D using Terzaghi’s consolidation theory assumptions. The effects of slurry layer height and weight on pore pressure are studied. At the end a comparison between numerical analysis results and field measurements is made.