Numerical Analyses of the Stress State in Two Neighboring Stopes Excavated and Backfilled in Sequence

Backfilling of underground stopes is commonly used in the mining industry. The stress state in these stopes has to be evaluated to ensure safe application of the backfill. In recent years, much work has been conducted to assess the stresses in single backfilled stopes. The stress distribution in stopes may also be affected by the excavation of multiple openings. This paper presents key results obtained from numerical simulations of two adjacent vertical stopes created in sequence. The results illustrate the influence of stope geometry (size and spacing), natural stress state, backfill properties, and excavation (and filling) sequence on the stress distribution in both stopes. The simulations indicate that the stress distribution in the first backfilled opening, following the creation of the second one, largely depends on the fill properties. These results also show the ways in which these factors may affect the stress magnitude and distribution pattern in the case of two adjacent stopes, when the creation of a second opening influences the response of the first one. It is also demonstrated that the second backfilled stope tends to behave in a manner similar to that of a single (isolated) stope, where a classical arching effect often dominates the stress distribution.