Study on damage evolution characteristics of sandstone under cyclic loading with acid-base dry-wet coupling effect
Weijing Yao,Shaoge Rui,Yongjiang Luo,Hanbing Xu,Jianyong Pang
Abstract
To investigate the influence mechanism of groundwater erosion on disturbed rocks during the excavation of coal mine roadways, multi-stage cyclic loading and unloading tests were conducted on sandstone samples treated under different acid-base dry-wet cycling conditions. Combined with Digital Image Correlation (DIC), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Energy Dispersive Spectroscopy (EDS), this study systematically analyzed the energy evolution, mechanical properties, damage variables, and strain field evolution of deteriorated sandstone, as well as the characteristics of its micro-morphology, phase composition, and element changes, thereby revealing the internal damage mechanism of sandstone. The results show that with the increase of cyclic grade, the deformation modulus of sandstone first increases sharply and then decreases slowly, while the cumulative residual strain and damage variables increase continuously, and acid-base erosion further amplifies the differences in the above mechanical parameters. The input energy, elastic energy, and dissipation energy of sandstone all increase with the rise of stress grade, and elastic energy always dominates the energy composition. The increase in the number of acid-base dry-wet cycles leads to a gradual separation of the growth curves of input energy and elastic energy, and the energy dissipation ratio shows a trend of first decreasing and then increasing. Strain field observations based on DIC technology indicate that sandstone fracture initiates from local strain concentration areas, followed by gradual propagation and coalescence of cracks, ultimately resulting in overall failure of the specimens. Microscopic tests demonstrate that acid-base solutions corrode sandstone samples and react chemically with the main components of sandstone, leading to an increase in the number of surface pores and cracks, while dry-wet cycles cause continuous shedding of rock particles. The coupling effect of chemical erosion and physical action leads to the continuous accumulation of internal damage in sandstone and the gradual aggravation of its deterioration. The findings of this research can serve as a theoretical foundation for evaluating the stability and designing support systems for underground structures affected by groundwater erosion, providing guidance for roadway support design and longterm stability assessment in water-eroded underground rock engineering.
Key Words
acid-base dry-wet cycles; cyclic loading and unloading; energy evolution; damage mechanism; sandstone
Address
Weijing Yao — State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China; School of Civil Engineering and Architecture, Anhui University of Science and Technology, Huainan 232001, China; Engineering Research Center of Underground Mine Construction, Ministry of Education, Anhui University of Science and Technology, Huainan 232001, China; Zhejiang Key Laboratory of Rock Mechanics and Geohazards, Shaoxing University, Shaoxing 312000, China
Shaoge Rui, Hanbing Xu — School of Civil Engineering and Architecture, Anhui University of Science and Technology, Huainan 232001, China
Yongjiang Luo — State Key Laboratory of Coal Mine Disaster Dynamics and Control, Chongqing University, Chongqing 400044, China
Jianyong Pang — School of Civil Engineering and Architecture, Anhui University of Science and Technology, Huainan 232001, China; Engineering Research Center of Underground Mine Construction, Ministry of Education, Anhui University of Science and Technology, Huainan 232001, China
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