NUMERICAL ANALYSIS OF STRESS DISTRIBUTIONS FOR MULTIPLE BACKFILLED STOPES

Over the past three decades, technological innovations with respect to cemented paste backfill (CPB) as a means of ground support has allowed for increased production within the mining industry, management mine waste costs, as well as the improvement of the overall health and safety of underground mining operations. Despite the extensive use of this relatively new ground support material, many fundamental factors affecting the design of safe and economical CPB structures are still not well understood.Recently, a significant amount of academic and industry research has been conducted to better understanding the distribution of stress with respect to primary-secondary extraction sequencing for stope-and-fill mining operations. While current, as well as past research, as provided a wealth of knowledge on the distribution of stress through the fill material itself, it lacks in providing an examination into the mechanism by which stress is able to redistribute itself through the backfill material as well as within the surrounding rockmass. The scope of this work is to optimize stope-and-fill extraction sequencing through the analysis of stress distributions as well as local and global stability of multiple narrow verticalfully-drained backfilled stopes. Scientific investigations into the behavior of the CPB material and surrounding rockmass will result in animproved understanding of how to better implement engineered paste-fill materials as a means of ground support for underground mining operations. Numerical simulations (FLAC3D and RocScience) were utilized in analyzing hypothetical (literature) as well as site-specific (field) case studies. While these simulations confirm generalized stress behaviors within the backfill material for single and adjacent stopes, stress redistributions within the surrounding rockmass as well as the rock-pillarindicate the development of tensile and compressive zones. From these results, one is able to better approximate ground and CPB instability with respect to site-specific conditions, geometries, and material properties. These simulations have been validated with respect to published analytical solutions, numerical simulations, and site-measurements for single (isolated) and adjacent narrow vertical fully-drained backfilled stopes