Continuous backfilling of cemented paste backfill? Yes, it’s possible with wick drains
PENGYU YANG (Polytechnique Montréal), Li Li (Polytechnique Montréal)
Cemented paste backfill (CPB) is one of the most popular backfills used by mining industries. In practice, a substantial amount of water is added into the fill mixture to facilitate its pipe transportation from surface backfill plant to underground stopes. Construction of barricades in access drifts near the drawpoints is necessary to hold the flowable fill in place. When the CPB is poured into the stope, a process called self-weight consolidation (or sedimentation) starts, leading to a generation of excess pore-water pressures in the fill. To avoid excessive fill pressure exercised on the barricade, filling operation is usually divided into two steps: plug pour and final (or bulk) pour. A curing time of several days is usually imposed before resuming the filling operation. This interruption is undesirable for mine production. Recently, the authors have performed some preliminary numerical modellings, showing that the application of wick drains in backfilled stopes would be a promising technique for accelerating the drainage and consolidation. In this paper, a more complete and systematic numerical analysis is performed to see the possibility of continuous backfilling by considering different and representative rise rates and material properties. The effect of different wick drain configurations is also studied.
Keywords:
Numerical modelling, Continuous backfilling, Consolidation, CPB, Wick Drains, Rise Rates
