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Evolution of Pore Structure and Fractal Characteristics in Red Sandstone under Cyclic Impact Loading

Authors :
Huanhuan Qiao
Peng Wang
Zhen Jiang
Yao Liu
Guanglin Tian
Bokun Zhao
Source :
Fractal and Fractional, Vol 8, Iss 8, p 437 (2024)
Publication Year :
2024
Publisher :
MDPI AG, 2024.

Abstract

Fatigue damage can occur in surface rock engineering due to various factors, including earthquakes, blasting, and impacts. The underlying cause for the variations in physical and mechanical properties of the rock resulting from impact loading is the alteration in the internal pore structure. To investigate the evolution characteristics of the pore structure under impact fatigue damage, red sandstone subjected to cyclic impact compression by split Hopkinson pressure bar (SHPB) was analyzed using nuclear magnetic resonance (NMR) technology. The parameters describing the evolution of pore structure were obtained and quantified using fractal methods. The development of the pore structure in rocks subjected to cyclic impact was quantitatively analyzed, and two fractal evolution models based on pore size and pore connectivity were constructed. The results indicate that with an increasing number of impact loading cycles, the porosity of the red sandstone gradually increases, the T2 cutoff (T2c) value decreases, the most probable gray value of magnetic resonance imaging (MRI) increases, the pores’ connectivity is enhanced, and the fractal dimension decreases gradually. Moreover, the pore distribution space tends to transition from three-dimensional to two-dimensional, suggesting the expansion of dominant pores into clusters, forming microfractures or even macroscopic fissures. The findings provide valuable insights into the impact fatigue characteristics of rocks from a microscopic perspective and contribute to the evaluation of time-varying stability and the assessment of progressive damage in rock engineering.

Details

Language :
English
ISSN :
25043110
Volume :
8
Issue :
8
Database :
Directory of Open Access Journals
Journal :
Fractal and Fractional
Publication Type :
Academic Journal
Accession number :
edsdoj.f606ffa0227846118cfe6ba7ad9f5775
Document Type :
article
Full Text :
https://doi.org/10.3390/fractalfract8080437