| This thesis addresses those mine design considerations applied to mining with backfill at Denison Mines Ltd., Elliot Lake, Ontario, and reviews the specific circumstances of pillar recovery during 1985 to 1988. The rock mechanics elements of the project are presented with a case history of pillar recovery in a specific stopping district (cost center).;The work undertaken to achieve this improved design includes both the study of the physical properties of the backfill, and its overall support characteristics. Design techniques involving analytical and numerical methods were coupled with ground behaviour data from daily monitoring and rock instrumentation.;The backfill cost center used as a case study is back analyzed with reference to a new proposed pillar strength classification system. Improvements in ground stability are assessed and comparisons with rock burst alleviation studies are made. The geomechanical parameters involving pillar design are discussed at length in the context of rock mechanics theory. This thesis attempts to demonstrate the manner in which an integrated design rationale may be employed in a room and pillar mining environment.;The use of hydraulically placed cemented tailings to recover additional ore reserves from rib pillars in a room and pillar mine required a design rationale beyond the traditional empirical approach. |
