Impacts of Cyclic Loading and Unloading Rates on Acoustic Emission Evolution and Felicity Effect of Instable Rock Mass

Abstract

Uniaxial cyclic loading-unloading compression experiments with schemes of six loading rates and six unloading rates were carried out on the combined testing platform. Impact of loading and unloading rates on rock AE characteristics was revealed. Results show that increasing loading and unloading rates resulted in decreasing total AE rings in the entire rock deformation and failure process. Increasing loading rate decreased the AE rings at loading stages, and increasing unloading rate decreased the AE rings at unloading stages in the same cycle. Total AE counts had a negative linear relationship to the loading and unloading rates. The loading stage was the active period of the AE phenomena, and impacts of the loading rate on the AE characteristics were more apparent. Especially when the loading rate was greater than 2.0 kN/s, brittle failure of rock specimens became noticeable. After the cyclic load reached the uniaxial compressive strength of 1/3∼1/2 times, the rock Felicity effect became more obvious. With the increase of the loading rate, the Felicity ratio decreased in the elastic stage and increased a little in the plastic stage, whereas with the increase of the unloading rate, the Felicity ratio decreased gradually in the elastic stage and remained almost the same in the plastic stage.

Mechanical and Acoustic Emission Behavior of Gangue Concrete under Uniaxial Compression

“…It can collect signals of 12 AE channels, 32 electric channels, and 6 transient electromagnetic channels simultaneously. This system has high sampling accuracy, 1.25 MHz real-time sampling frequency, 50 kHz maximum response frequency, 24-bit A/D conversion, dynamic range ≥ 258 dB, and 10 0 –10 6 time-varying gain [29]. Limited by the experimental purpose, only part of AE monitoring was used in this study.…”

Fracture analysis of three‐point bending notched granite beams under prepeak and postpeak cyclic loading by digital image correlation and acoustic emission techniques

“…In contrast, the AE characteristics under cyclic loading are very different. Zhang et al 31 revealed the influence of loading and unloading rate on the AE characteristics of rock in uniaxial compression tests, and found that the total number of AE events has a negative linear relationship with the loading and unloading rate. Liu et al 32 used the spatial distribution of acoustic emission events and the changes in the cumulative count of acoustic emission to illustrate the evolution of microcracks caused by cyclic stress in tension and compression.…”

Mechanical Properties of Metasandstone under Uniaxial Graded Cyclic Loading and Unloading

“…L. Wu studied the thermal infrared radiation energy characteristics of granite under cyclic loading and unloading conditions [4]. M. Zhang pointed out that increasing the loading and unloading rate will reduce the total acoustic emission ring of red sandstone samples, and the total acoustic emission count of rock samples has a negative linear relationship with the loading and unloading rate [5]. H. Wang proposed that the loading/unloading response ratio (LURR) can be used to evaluate the damage of coal and rock under cyclic load [6].…”