Loading rate effect on uniaxial compressive strength behavior and acoustic emission properties of cemented tailings backfill

摘要

To understand the quality and behavior of cemented tailings backfill (CTB) subjected to dynamic loads, the influence of change in the rate of loading should be accurately determined for an efficient mine fill design. In this study, the compressive strength behavior and acoustic emission (AE) characteristics of 180-day cured CTB samples are investigated by using four different loading rates: 50 N/s, 100 N/s, 150 N/s, and 200 N/s. Samples were prepared with the classified tailings and cementitious material of a gold mine as raw materials and subjected to the uniaxial compressive test using mechanical testing machine (GAW-2000) and AE equipment (PCI-2). Experimental results indicate that: (1) the loading rate has a strengthening effect on long-term strength behavior of CTB samples, and there is a power function between peak compressive strength of CTB samples and loading rate. The stress state of the backfill mass is "stepped" growth before the peak compressive strength, and the whole process displays a multi-cycle of "surge-steady-surge-steady"; (2) during the loading process, the ring count distribution has a regular peak-spacing effect, and the cumulative ring counts are also "stepped" and inclined to be stable. (3) With the increase of loading rate, the failure mode of CTB is a transition from tensile and shear mixing (mainly shear stress) to X-type shear failure. Ultimately, the essential findings of this experimental work will provide a scientific reference for studying the dynamic characteristics of CTB samples. (C) 2019 Elsevier Ltd. All rights reserved.