Relationship Between Microstructure and Long‐Term Strength of Compacted Q 2 Loess Under High Confining Pressure

The microstructure of compacted loess exerts a substantial influence on its long‐term strength. Gaining a comprehensive understanding of the law governing how microstructural changes affect its long‐term strength is conducive to guiding the construction of high‐fill loess projects. To delve into the abovementioned issues, we conducted triaxial creep tests on Q 2 loess samples collected from Yan’an, Shaanxi Province, under varying levels of soil compactness. Scanning electron microscopy (SEM), coupled with image processing techniques, was employed to analyze the pore microstructure characteristics of compacted loess following creep deformation. Furthermore, multivariate regression analysis was applied to investigate the correlation between the long‐term strength of compacted loess and its microstructural pore parameters. The experimental results indicated that an increase in compactness significantly enhances the creep resistance of loess. Under higher confining pressures, the long‐term strength of loess demonstrates a nonlinear increasing trend with increasing compactness. From a microstructural perspective, as compactness increases, the number of large pores decreases, while the number of small pores increases, leading to an overall reduction in both pore volume and pore size. Among the various pore parameters, the pore area ratio and average pore length were identified as the most influential factors affecting the variation in long‐term strength under different compactness conditions. This research serves as a reference for elucidating the relationship between the microstructure of compacted loess and its long‐term strength.