The compressibility of mining backfill governs its resistance to the closure of surrounding rock mass, which should be well reflected in numerical modeling. In most numerical simulations of backfill, the Mohr–Coulomb elasto-plastic model is used, but is constantly criticized for its poor representativeness to the mechanical response of geomaterials. Finding an appropriate constitutive model to better represent the compressibility of mining backfill is critical and necessary. In this paper, Mohr–Coulomb elasto-plastic model, double-yield model, and Soft Soil model are briefly recalled. Their applicability to describing the backfill compressibility is then assessed by comparing numerical and experimental results of one-dimensional consolidation and consolidated drained triaxial compression tests made on lowly cemented backfills available in the literature. The comparisons show that the Soft Soil model can be used to properly describe the experimental results while the application of the Mohr–Coulomb model and double-yield model shows poor description on the compressibility of the backfill submitted to large and cycle loading. A further application of the Soft Soil model to the case of a backfilled stope overlying a sill mat shows stress distributions close to those obtained by applying the Mohr–Coulomb model when rock wall closure is absent. After excavating the underlying stope, rock wall closure is generated and exercises compression on the overlying backfill. Compared to the results obtained by applying the Soft Soil model, an application of the Mohr–Coulomb model tends to overestimate the stresses in the backfill when the mine depth is small and underestimate the stresses when the mine depth is large due to the poor description of fill compressibility. The Soft Soil model is recommended to describe the compressibility of uncemented or lightly cemented backfill with small cohesions under external compressions associated with rock wall closure.

Backfill is often employed in mining operations for ground support, with its positive impact on ground stability acknowledged in many underground mines. However, existing studies have predominantly focused only on the stress development within the backfill material, leaving the influence of stope backfilling on stress distribution in surrounding rock mass and ground stability largely unexplored. Therefore, this paper presents numerical models in FLAC3D to investigate, for the first time, the time-dependent stress redistribution around a vertical backfilled stope and its implications on ground stability, considering the creep of surrounding rock mass. Using the Soft Soil constitutive model, the compressibility of backfill under large pressure was captured. It is found that the creep deformation of rock mass exercises compression on backfill and results in a less void ratio and increased modulus for fill material. The compacted backfill conversely influenced the stress distribution and ground stability of rock mass which was a combined effect of wall creep and compressibility of backfill. With the increase of time or/and creep deformation, the minimum principal stress in the rocks surrounding the backfilled stope increased towards the pre-mining stress state, while the deviatoric stress reduces leading to an increased factor of safety and improved ground stability. This improvement effect of backfill on ground stability increased with the increase of mine depth and stope height, while it is also more pronounced for the narrow stope, the backfill with a smaller compression index, and the soft rocks with a smaller viscosity coefficient. Furthermore, the results emphasize the importance of minimizing empty time and backfilling extracted stope as soon as possible for ground control. Reduction of filling gap height enhances the local stability around the roof of stope.