中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 35 No. 6 June 2025 |
（1. School of Resources and Safety Engineering, Central South University, Changsha 410083, China;
2. School of Geosciences and Info-physics, Central South University, Changsha 410083, China;
3. School of Mine Safety, North China Institute of Science and Technology, Langfang 065201, China;
4. Zhongnan Engineering Corporation Limited, Changsha 410014, China）
Abstract:A series of acoustic emission (AE)-integrated conventional triaxial compression tests (CTTs) were conducted to evaluate the mechanical properties of hard red sandstone. Under conventional triaxial stress states, the crack closure stress, crack initiation stress, and damage stress ranged in 13.75%-22.34%, 31.84%-42.19%, and 63.85%-75.93% of the peak strength of sandstone, respectively. The AE parameters reflected the confining pressure (σ3) effect on microcrack propagation, with σ3=5 MPa identified as the threshold affecting both the timing of numerous AE hits and the distribution range of peak frequencies of AE signals before the final failure of each specimen. The AE property analysis showed that shear cracks played a dominant role in rock failure in CCTs, which ranged in 60%-85% of the total number of cracks. A smaller σ3 value promoted shear failure, whereas a larger σ3 value inhibited it. Furthermore, the appropriate dataset selection range to accurately calculate the cohesion force and internal friction angle in CTTs and variable-angle shear tests was determined.
Key words: red sandstone; mechanical parameters; stress threshold, acoustic emission characteristics; internal friction angle; cohesion force
