To investigate the impact of underground multiple stress disturbances on the long-term stability of cemented tailings backfill (CTB), this study conducted experiments under different disturbance levels (20–80% of static strength) and frequencies (1–4 times). By comprehensively utilizing mechanical testing, wave velocity monitoring, digital image correlation (DIC), and scanning electron microscopy (SEM), the “heterogeneous” evolution mechanism of macro-micro damage was revealed. The results indicate that disturbance level and frequency exert distinctly different driving effects on the deterioration of CTB, rather than a simple linear superposition. Specifically, low-frequency disturbance produces a compaction strengthening effect, microscopically promoting the generation of Ca(OH)₂ and ettringite (increased Ca/Si ratio). In contrast, the combination of high disturbance and high frequency induces free water extrusion and inhibits hydration, leading to an advanced damage threshold based on energy evolution and the accelerated coalescence of microcracks, which favors the formation of C-S-H gel (decreased Ca/Si ratio). Within this heterogeneous mechanism, the disturbance level acts as the dominant controlling factor. This study clarifies the nonlinear mechanical and chemical evolution paths under composite disturbances, providing theoretical support for the dynamic stability control of backfill in deep multi-step mining.

To achieve the resource utilization of waste tires and improve the mechanical performance of cemented tailings backfill, rubber–cemented tailings backfill (R-CTB) specimens were prepared with four rubber particle sizes (20-, 40-, 60-, and 80-mesh) and four contents (2%, 4%, 6%, and 8%). A 0% rubber control group was introduced to address the lack of quantitative comparison. Uniaxial compression, digital image correlation (DIC), and scanning electron microscopy (SEM) were used to study mechanical behavior, energy evolution, and microstructural characteristics at 7 and 28 days. Results indicate that strength and elastic modulus first increase then decrease with particle size and decrease with content rise. Compared with the control group, R-CTB shows lower strength but significantly higher ductility and energy dissipation. Finer particles cause strain localization; higher content and finer size increase pores and weaken interfaces. Rubber incorporation transforms failure from brittle to ductile, providing a basis for engineering application.

To address the delayed strength development and uncertain rock-backfill interfacial stability of total-tailings paste backfill under low-temperature underground conditions, this study aims to quantify the coupled effects of slurry mass concentration, cement/tailing (C/T) ratio, curing temperature, and curing age on uniaxial compressive strength, and to clarify how interface roughness and curing age govern interfacial shear behavior and field strength. A silver–lead–zinc mine in Inner Mongolia was selected as the engineering background, and uniaxial compression, double-sided shear, SEM, and in situ strength tests were conducted. Results show that UCS increased with curing temperature, curing age, slurry mass concentration, and C/T ratio within the investigated ranges, with the comparative influence following the order: C/T ratio > curing age > curing temperature ≈ slurry mass concentration. With age, hydration products increased, pores and microcracks decreased, and structure densified. When joint roughness coefficient (JRC) increased from 0 to 26.76, cohesion rose from 93.31 to 965.57 kPa, and the failure mode shifted from interface slip to backfill shear. Increasing age from 3 to 7d raised cohesion from 611.02 to 965.57 kPa and the internal friction angle from 29.09° to 33.98°. Optimal conditions were 66% concentration and 15 °C, with C/T ratios of 1:4 (adhesive layer) and 1:8 (ordinary layer). Test results under various ratios and ages all indicate that the underground backfill has attained early self-standing and bearing capacity.