The paper analyzes the effects of filling times and filling interval time on the acoustic emission characteristics and coda wave characteristics of layered cemented tailings backfill under uniaxial compression and, to a certain extent, enriches the study of layered cemented tailings backfill in this field. The work aims to monitor the early warning of layered cemented tailings backfill with different layering factors during deformation and damage by the changing law of acoustic emission and ultrasonic signals. By conducting uniaxial compression tests, acoustic emission, and ultrasonic tests of layered cemented tailings backfill, the acoustic emission parameters and their fractal characteristics of layered cemented tailings backfill with different layering factors during uniaxial compression were calculated. Meanwhile, the variation law of the coda wave velocity variation rate of layered cemented tailings backfill during uniaxial loading was analyzed using coda wave interferometry. The test results show the feasibility of using acoustic emission and ultrasonic means to monitor and warn about the deformation damage of layered cemented tailings backfill.

Tailings dams are structures that store both tailings and water, so almost all tailings dam accidents are water related. This paper investigates a tailings dam’s failure pattern and damage development under flood conditions by conducting a 1:100 large-scale tailings dam failure model test. It also simulates the tailings dam breach discharge process based on the breach mode using FLOW-3D software, and the extent of the impact of the dam failure debris flow downstream was derived. Dam failure tests show that the form of dam failure under flood conditions is seepage failure. The damage manifests itself in the form of flowing soil, which is broadly divided into two processes: the seepage stabilization phase and the flowing soil development damage phase. The dam failure test shows that the rate of rise in the height of the dam saturation line is faster and then slower. The order of the saturation line at the dam face is second-level sub-dam, third-level sub-dam, first-level sub-dam, and fourth-level sub-dam. The final failure of the tailings dam is the production of a breach at the top of the dam due to the development of the dam’s fluid damage zone to the dam top. The simulated dam breach release results show that by the time the dam breach fluid is released at 300 s, the area of over mud has reached 95,250 square meters. Local farmland and roads were submerged, and other facilities and buildings would be damaged to varying degrees. Based on the data from these studies, targeted measures for rectifying hidden dangers and preventing dam breaks from both technical and management aspects can be proposed for tailings dams.

The strength of cemented paste backfill (CPB) directly affects mining safety and progress. At present, in-situ backfill strength is obtained by conducting uniaxial compression tests on backfill core samples. At the same time, it is time-consuming, and the integrity of samples cannot be guaranteed. Therefore guided wave technique as a nondestructive inspection method is proposed for the strength development monitoring of cemented paste backfill. In this paper, the acoustic parameters of guided wave propagation in the different cement-tailings ratios (1:4, 1:8) and different curing times (within 42 d) of CPBs were measured. Combined with the uniaxial compression strength of CPB, relationships between CPB strength and the guided wave acoustic parameters were established. Results indicate that with the increase of backfill curing time, the guided wave velocity decreases sharply at first; on the contrary, attenuation of guided waves increases dramatically. Finally, both velocity and attenuation tend to be stable. When the CPB strength increases with curing time, guided wave velocity shows an exponentially decreasing trend, while the guided wave attenuation shows an exponentially increasing trend with the increase of the CPB strength. Based on the relationship curves between CPB strength and guided wave velocity and attenuation, the guided wave technique in monitoring the strength development of CPB proves feasible.

The guided wave technique is applied to slope stability monitoring to overcome the high attenuation characteristics of acoustic emission propagation in rock and soil materials. The shear tests of “guided wave meter” (GWM) with different deformation rates were carried out, and the effects of the material and particle size of the coupling medium and the diameter of the waveguide rod on the flexural guided wave ring down count were studied, and the relationship between the deformation rate of the slope and the flexural guided wave parameters was analyzed. The results show that the flexural guided wave ring down count rate increases with the increase of deformation in the loading process. The GWM filled with quartz sand particles produces more flexural guided wave ring down counts than those filled with gravel particles. From the twelve groups of GWM shear tests, it can be seen that the GWM with the combination of 16 mm waveguide rod and 4–8 mm quartz sand produces the highest cumulative flexural guided wave ring down counts. The combination is used as an optimized GWM. By applying different deformation rates to the optimized GWM, it was found that the flexural guided wave ring down count rate at different deformation rates tended to increase and was distributed in a fan shape. The cumulative flexural guided wave ring down count has an excellent linear correlation with the deformation. The slope of the cumulative ring down count curves and the deformation curves are obtained separately, which shows that the deformation rate has an excellent linear relationship with the slope of the cumulative ring down count curve, and the slope of the cumulative ring down count curve increases with the increase of the deformation rate. It provides theoretical guidance for quantifying the slope deformation rate using the flexural guided waves.

Using the two-dimensional Particle Flow Code (PFC2D), a model of red sandstone containing fractures with different inclination angles under impact load was established to study the influence of fracture inclination angles on the dynamic compressive strength, stress wave attenuation, and crack evolution laws of the model. The results indicate that, under the same impact load, the dynamic compressive strength of the cracked specimens exhibits a “V”-shaped variation, with the specimen at a 45° inclination angle showing the lowest strength. The influence of inclination angles on strength is most significant in the 30° to 45° inclined specimens. As the inclination angle increases, the reflection coefficient rises, the transmission coefficient decreases, stress wave attenuation intensifies, and the time for specimen penetration shortens, making the specimen more prone to failure. The location of crack initiation shifts toward the middle of the fracture as the inclination angle increases, and the cracks tend to develop parallel to the impact load. When the inclination angle is ≥45°, stress concentration at fracture tips prolongs the shear-dominated phase during failure progression. However, the tensile ratio k consistently exceeds 0.7 at ultimate failure, indicating tensile mechanisms remain the dominant failure mode. Both absorbed energy and total crack number generally decrease with increasing inclination angle, while no clear correlation exists between absorbed energy and fragment number. Large fragments are distributed on both sides of the fracture during the fragmentation process. In contrast, small fragments concentrate near the through cracks. Specimens with 45° and 60° inclination angles exhibit a higher number of fragments and more significant fragmentation. In the initial loading stage, the specimen with a 90° inclination angle shows the weakest resistance to failure, while the 0° inclination angle specimen exhibits the strongest resistance. The research findings contribute to elucidating the dynamic failure mechanisms of fractured red sandstone, analyzing slope stability, and optimizing blasting designs.