During the process of constructional backfill mining, the cemented paste backfill (CPB) typically exhibits a high degree of brittleness and limited resistance to failure. In this study, the mechanical and damage evolution characteristics of waste tire steel fiber (WTSF)-modified CPB were studied through uniaxial compression tests, acoustic emission (AE) tests, and scanning electron microscopy (SEM). The results showed that the uniaxial compressive strength (UCS) decreased when the WTSF content was 0.5%, 1%, and 1.5%. When the WTSF content reached 1%, the UCS of the modified CPB exhibited a minimal decrease (0.37 MPa) compared to that without WTSF. When the WTSF content was 0.5%, 1%, and 1.5%, peak strain of the WTSF-modified CPB increased by 18%, 31.33%, and 81.33%, while the elastic modulus decreased by 21.31%, 26.21%, and 45.42%, respectively. The addition of WTSF enhances the activity of AE events in the modified CPB, resulting in a slower progression of the entire failure process. After the failure, the modified CPB retained a certain level of load-bearing capacity. Generally, the failure of the CPB was dominated by tensile cracks. After the addition of WTSF, a gradual increase in the proportion of tensile cracks was observed upon loading the modified CPB sample to the pore compaction stage. The three-dimensional localization of AE events showed that the WTSF-modified CPB underwent progressive damage during the loading, and the samples still showed good integrity after failure. Additionally, the response relationship between energy evolution and damage development of WTSF-modified CPB during uniaxial compression was analyzed, and the damage constitutive model of CPB samples with different WTSF contents was constructed. This study provides a theoretical basis for the enhancement of CPB modified by adding WTSF, serving as a valuable reference for the design of CPB constructional backfill.

中文翻译：

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废旧轮胎钢纤维改性水泥浆体回填体力学性能及损伤演化特征


在建筑回填采矿过程中，胶结膏体回填（CPB）通常表现出高度的脆性和有限的抗破坏能力。本研究通过单轴压缩试验、声发射（AE）试验和扫描电子显微镜（SEM）研究了废旧轮胎钢纤维（WTSF）改性CPB的力学和损伤演化特征。结果表明，当WTSF含量为0.5%、1%和1.5%时，单轴抗压强度（UCS）下降。当WTSF含量达到1%时，与没有WTSF的情况相比，改进的CPB的UCS表现出最小的降低（0.37 MPa）。当WTSF含量为0.5%、1%和1.5%时,WTSF改性CPB的峰值应变分别增加了18%、31.33%和81.33%,而弹性模量分别下降了21.31%、26.21%和45.42% ， 分别。 WTSF 的添加增强了改良 CPB 中 AE 事件的活性，从而减慢了整个故障过程的进展。失效后，改装后的CPB保留了一定水平的承载能力。一般来说，CPB的失效以拉伸裂纹为主。添加WTSF后，将改性CPB样品加载到孔隙压实阶段时，观察到拉伸裂纹的比例逐渐增加。 AE事件的三维定位表明，WTSF改进的CPB在加载过程中经历了渐进性损伤，并且样品在失效后仍然表现出良好的完整性。此外，分析了WTSF改性CPB单轴压缩过程中能量演化与损伤发展的响应关系，构建了不同WTSF含量的CPB样品的损伤本构模型。 本研究为添加WTSF增强CPB改性提供了理论依据，为CPB建筑回填土的设计提供了有价值的参考。