Research progress on the mechanical properties of cemented tailings backfill under multi-field coupling environments

In the strength design of stope backfills, the mixture ratio of backfill materials is conventionally determined based on the strength of backfill specimens under laboratory standard curing conditions. However, a significant discrepancy exists between laboratory standard curing conditions and the actual underground environment characterized by multi-physics field coupling. This discrepancy compromises the rationality of strength design, leading to either excessive backfill costs. This paper aims to systematically review the mechanical response mechanisms and microstructural evolution laws of Cemented Tailings Backfill （CTB） under multi-field coupling environments. Combining literature review with theoretical analysis, this study systematically summarizes the latest domestic and international research findings concerning the effects of stress fields, temperature fields, and their coupling with seepage and chemical fields on the mechanical properties of CTB. Emphasis is placed on analyzing the evolution of experimental apparatus from uniaxial low-pressure to three-dimensional high-pressure systems, and from constant ambient temperature to deep geothermal variable-temperature environments. Furthermore, macro-microscopic experimental data under different multi-field coupling paths are comparatively analyzed. The results indicate that regarding the stress field, the application of stress significantly enhances strength through physical compaction and the acceleration of the hydration reaction of cementitious materials. Regarding the temperature field, although high temperatures provide thermal activation energy to accelerate early strength formation, long-term exposure to high geothermal environments leads to uneven distribution of hydration products and coarsening of microscopic pores. In terms of multi-field coupling, it is found that applying stress under drainage conditions effectively inhibits microstructural deterioration caused by high temperatures. Curing stress dominates the dry density and porosity of the backfill, while temperature governs the degree of hydration; notably, high stress can compensate for the thermal damage caused by high temperatures. Reproducing the deep in-situ multi-field coupled environment in the laboratory serves as the foundation for related research. Future studies should shift from static single-factor analysis to dynamic multi-field coupling, focusing on the development of experimental systems capable of simulating three-dimensional geostress states and real-time dynamic control, thereby achieving precision and economy in deep mine backfill design.