Prepeak energy evolution properties of sandstone subject to diametrical splitting with different loading rates

• Published in: IOP conference series. Earth and environmental science Vol. 861; no. 2; pp. 22037 - 22044
• Main Authors: Luo, Song, Gong, Fengqiang
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.10.2021
• Subjects: Energy; Energy dissipation; Energy storage; Evolution; Linear functions; Load distribution; Loading rate; Mathematical analysis; Mechanical properties; Parameters; Rocks; Sandstone; Splitting; Storage coefficient; Unloading
• ISSN: 1755-1307; 1755-1315
• DOI: 10.1088/1755-1315/861/2/022037

To understand the energy evolution properties during rock splitting under different loading rates, four groups of Brazilian test with a loading-unloading cycle corresponding to four orders of magnitude of controlled loading rate (10−1, 100, 101, 102 kN/min) were conducted on red sandstone using the MTS 322 testing system. The energy characteristics were interpreted by mathematically integrating the force-displacement responses of the tested rock specimens. It was found that at each loading rate, the input energy was a linear function as the elastic energy and dissipated energy, while these three types of energy nonlinearly grew with the unloading level. Importantly, the loading rate was found to exert an insignificant influence on the evolution of the linear energy properties (referring to the linear functions between the three types of energy); the energy storage coefficient (ESC) and/or energy dissipation coefficient (EDC) remained constant under various loading rates, exhibiting an approximate independency on loading rate. Based on this, a unified formula for describing the rate-independence of linear energy properties was presented in the tested loading rate range. It is also noted that rock mechanical parameters such as the peak force and peak displacement and the ESC and EDC are closely comparable versus the increasing loading rate, and hence the energy parameters are likely to be used to characterize the rock mechanical ones. Finally, the relevancy between energy allocation and rock failure patterns was discussed.