Triaxial creep characteristics and microstructure of red sandstone under acidic dry-wet cycles

Abstract To investigate the influence of acidic dry-wet cycles on triaxial creep behavior, red sandstone samples from the Three Gorges Reservoir area (Chongqing) were subjected to triaxial creep tests and microstructural observations under different dry-wet cycles in acidic environments. The test results showed that: (1) As the number of acidic dry-wet cycles increases, the creep strain, steady-state creep rate, and total damage factor of the samples exhibit an increasing trend, while the average elastic modulus and long-term strength progressively decline. Furthermore, the variations in creep parameters are more pronounced in acidic solutions compared to neutral solutions. The acidic environment accelerates the degradation of the rock structure and its creep mechanical properties, rendering the rock more vulnerable to damage induced by dry-wet cycles. (2) The combined effects of dry-wet cycles and acidic corrosion induce a synergistic deterioration of the rock’s microstructure, characterized by an increase in pore density, expansion of pore sizes, and the development of larger pores and new microcracks. The microstructural damage progressively intensifies under the coupled influence of these factors. The findings provide a scientific basis for the analysis of long-term stability in geotechnical engineering under the influence of acidic dry-wet cycles.