Optimizing the mechanical characteristics of cemented tailings backfill (CTB) and quickly identifying its damage state under external loading, this study compares and prepares CTB specimens without fiber, doped with polypropylene fiber (PF), doped with glass fiber (BL), and doped with polypropylene and glass blended fiber (PB). Uniaxial compression and acoustic emission (AE) monitoring experiments are also conducted. Based on the cumulative energy of AE, the damage ontology model of CTB was developed. As shown by the study’s findings, adding various fibers can greatly enhance the filler body’s uniaxial compressive strength (UCS). BL has the greatest effect, followed by PB, while PFs have the least effect. Furthermore, the fibers primarily prevent the growth of crack extension by extending or breaking themselves, The results of the tests on acoustic emission revealed that the fiberless filler’s signals were more active prior to the peak point and less intense in the later stages of the damage, whereas the fiber-doped filler’s signals began to increase following the peak point and remained high. Thus, the damage model curves of various fiber-filled bodies are constructed based on the cumulative energy of acoustic emission, and the experimental data verification shows that the two have good consistency, suggesting that the established theoretical model can serve as a basis of reference for assessing the filled bodies’ damage state.

To investigate the mechanical properties, energy damage evolution law, and crack evolution characteristics of doped basalt fiber (BF) and calcium carbonate whisker (CW) cemented sand filler (CPB), uniaxial compression experiments combined with microstructural characterization were conducted on the doped fiber cemented filler specimens to analyze their energy dissipation characteristics, and a segmental damage constitutive model was established based on the damage mechanics theory. The experimental results show that the appropriate amount of BF (the optimal dosage is 0.1%) and CW (the optimal dosage is 1%) can significantly improve the uniaxial compressive strength and ductility of the filling body. The two synergistic actions show a coupling enhancement effect so that the compressive strength of the filling body increased by 33.68%. The total strain energy, elastic strain energy, and dissipation energy of the mixed fiber cemented sand filling body before the peak stress showed different trends; at the same time, based on the damage theory to optimize the existing damage constitutive model of the applicable fiber filling body, the introduction of the damage correction factor α, the establishment of a segmented damage constitutive model considering the compaction stage and the influence of fibers, and found that the experimental curves and the theoretical curves match with the degree of agreement of more than 90%. Under uniaxial loading, the specimens of the filler not doped with BF usually showed brittle damage characteristics, and the main crack through the specimen appeared. However, after BF was doped, the damage mode changed to pure shear damage or mixed tensile-shear damage, with “Y” type cracks and multiple small microcracks, which indicated that BF could inhibit the crack extension, disperse the stress, and reduce the phenomenon of stress concentration, thus improving the ductility and safety of the filled body. In addition, Microanalysis showed that the synergistic enhancement of BF and CW improved the pore structure of the matrix, and the attachment of more hydration products on the surface of BF and CW promoted the fiber-matrix bonding, which effectively inhibited the emergence and expansion of internal cracks. This study provides valuable insights to improve the utilization of tailings and enhance the stability of mine fill bodies.

The measurement of rock joint parameters is a hotly debated and difficult problem in rock mechanics. Joints have great influence on the propagation of stress waves in rock mass. Since the multiple reflections of stress waves propagating inside the joints is not considered accurately, the reflection wave shape cannot be obtained by using a discontinuous displacement model to describe the deformation characteristics of joints. A joint is regarded as a rock using the first analysis of the stress wave transmission in the course of a single joint and the propagation law of a reflection wave. For rocks orientated in the same direction with the same type of wave superposition, stress wave parameters can be established through the multiple reflection effect of a single-joint analysis model. Further to this, analysis using an extended single-joint model can estimate a stress wave under the condition of a vertical incidence group parallel strata analysis model. Taking a single macro-joint as an example, a measuring line is arranged in the normal direction of the joint, and two measuring points on both sides of the joint are arranged in a line to record the waveforms of the incident and transmitted waves. According to the established single-joint analysis model, the calculated waveform of the incident side measuring point is calculated by using the measured waveform of the transmission side measuring point, and the measured waveform of the incident side measuring point is compared with the measured waveform of the incident side measuring point, and the joint elastic parameters with the minimum error are obtained by using the principle of least square method. Six tests were carried out through joints with a thickness of 0.04 m. The results show that the primary wave (P-wave) and secondary vertical wave (SV wave) velocity of joints obtained from many tests have good consistency, which indicates that the joint analysis model has good stability, and the test solution of joint elastic parameters based on the model is reliable.