胶结充填体应变率与声发射特征响应规律

Strain rate and acoustic emission characteristic response law of cemented backfill

应变率是影响胶结充填体力学特性和声发射特征的重要因素.为研究胶结充填体应变率与声发射特征响应规律,文中进行了单轴压缩条件下胶结充填体的声发射试验,研究了应变率、声发射在加载过程中的时序特征,探讨了应变率与声发射时序特征之间的相关性,以及两者变化趋势之间的内在联系,进一步揭示了荷载作用下胶结充填体的裂纹演化规律.结果表明:胶结充填体应变率、振铃计数率在变形全过程均表现出“升→降→稳→升”的变化趋势和阶段性特征,两者相关性较高;胶结充填体内部破裂是由骨料之间的摩擦以及胶结材料的断裂演化造成,应变率对声发射特征在一定程度上起到了支配作用;基于应变率在塑性屈服和失稳破坏阶段表现出明显的突变性,可为胶结充填体破裂预测提供有效的前兆信息;结合声发射振铃计数率、平静期以及扩容现象可更加全面的反映胶结充填体破裂情况.研究结果可为胶结充填体力学特性研究奠定理论基础.

Strain rate is an important factor affecting the mechanical properties and acoustic emission characteristics of cemented backfill. In order to study the strain rate and the acoustic emission response of cemented backfill, the acoustic emission test of cemented backfill under uniaxial compression was carried out. The strain rate and the timing characteristics of acoustic emission during loading were studied. The correlation between strain rate and acoustic emission timing characteristics as well as the intrinsic relationship between the two trends were discussed, which further revealed the crack evolution law of the cemented backfill under load. Results show that the strain rate and ringing count rate of cemented fillings had the variation trend and phase characteristics of “up→down→steady→up” in the whole process of deformation, and the correlation between them was high. The internal rupture of the cemented backfill was caused by the friction between the aggregate and the fracture evolution of the cemented material. The strain rate played a dominant role in the acoustic emission characteristics. The strain rate in the stage of plastic yield and instability, showed obvious abruptness, which could provide effective precursor information for the prediction of cemented backfill fracture. The combination of acoustic emission ringing count rate, quiet period, and expansion could better reflect the rupture of cemented backfill. The research results can lay a theoretical foundation for the study of mechanical properties of cemented backfill.