Required Plug Strength for Continuously Poured Cemented Paste Backfill in Longhole Stopes

Continuously poured paste backfill dramatically improves underground mining efficiency through reduced stope cycle time and simplified logistics. For longhole stopes, a “plug” is to few meters above the undercut brow must gain sufficient strength prevent failure plug when “main” pour begins. A novel, rational engineering design approach that determines required developed. The potential mechanism during continuous pouring identified theoretical solution its numerical validation/calibration are discussed. Four field case histories then used, three of them involving pours, demonstrate solution’s validity in back-analysis. These studies unique extent quality total stress water pressure measurements made throughout backfilling. Additionally, comprehensive laboratory data available characterize development binder hydration first days, which critical back-analyses. Results indicate backfilling feasible with reasonably attainable strengths at most mines. However, mines undertake early testing, carry out ensure placed behaviour consistent analysis assumptions.