Dynamic response of cement-tailings matrix composites under SHPB compression load

Abstract

Investigating the dynamic response of cemented tailings backfill (CTB) is a challenging task since there is a lack of the sophisticated laboratory device and the costs linked with extraction of ore in the stopes using explosives are relatively high. In this study, the variations in the dynamic peak compressive strength (DPCS), cement-to-tailings ratio (c/t), and curing time (CT) of nine types of cement-tailings matrix composites (CTMC) were investigated under impact loading strain rates ranging from 10 s−1 to 100 s−1 using a split Hopkinson pressure bar (SHPB). Physical and chemical characteristics of tailings from a gold mine were tested. A series of dynamical compressive strength test and microstructural analysis were conducted to determine the relationships between DPCS of CTMC and three factors of average strain rate (ASR), cement-to-tailings ratio (c/t) and curing time. A total of 36 CTMC samples with a diameter × height of 50 mm × 25 mm prepared at different c/t (1:4, 1:6 and 1:8) and CT (28, 56, and 90 d) values were subjected to DPCS test. The results shows that: (1) DPCS results increased with an increase in ASR. Different types of curve fitting were conducted to obtain the correlation between DPCS and ASR. An exponential function was used to explain the relationship between DPCS and ASR. (2) As the ASR increases, the dynamic increase factor (DIF) value increases. The exponential function can be used to characterize the quantitative relation between DIF and lgASR. (3) When the results of the experiment and the ANSYS/LS-DYNA numerical simulation were compared, the stress-strain and the failure characteristics of the CTMC and DPCS with impact velocity are consistent. The results of this study can provide significant reference for the backfill design of underground mining.