Influence of structural factors on uniaxial compressive strength of cemented tailings backfill

In this paper, the influence of structural factors on the uniaxial compressive strength (UCS) of cemented tailings backfill (CTB) was experimentally investigated focusing on the filling time (FT), filling interval time (FIT) and filling surface angle (FSA). A number of CTB samples with a diameter × height of 50 mm and height of 100 mm were prepared at different FTs (1, 2, 3, and 4 stages), FITs (12, 24, 36, and 48 h), and FSAs (0, 15, 30, 45, and 60°) and subjected to UCS test to determine their mechanical strength performance. Results show that: (1) The UCS of the CTB samples decreased with the increase in FTs. The polynomial could represent the quantitative relationship between the backfill strength and FT. When the solid density (SD) within the CTB was constant, the value of the strength reduction coefficient k gradually decreased with the increase in FTs. When the SD was 65-75 wt%, the corresponding value of k remained between 0.592 and 0.967. (2) With the extension of the FIT, the UCS values of the CTB samples gradually decreased. The polynomial function could characterize the quantitative relationship between the UCS and FIT. The FIT only slightly influenced the strength performance of the CTB samples. The failure mode of the CTB samples may be tensile failure-transition from tensile failure to the shear failure-tensile shear pattern with the increase in the FIT. (3) The UCS showed a U-type distribution that decreased first and then increased with the increase in the FSAs. When the FSA changed from 0° to 60°, the UCS of the CTB samples first decreased and then increased with the FSA. The results presented in this study contribute to a better understanding of the effect of structural factors on CTB's mechanical properties.