3D structural correlations to strength deterioration of sliding zone soil impacted by physicochemical interactions

Physicochemical interactions accelerate the internal structural degradation of reservoir landslides in the Three Gorges Reservoir area, potentially triggering catastrophic failures, thus necessitating the need to accurately link structural changes with mechanical deterioration within the sliding zone. This study investigates the combined effects of wet-dry cycles and chemical environments (acidic, saline, and distilled water) on the shear strength and three-dimensional (3D) structure of sliding zone soil through triaxial test and computed tomography (CT). Results imply that physicochemical processes, modulated by chemical agents, drive an exponential decline in shear strength over wet-dry cycles by progressive alteration of 3D pore structure. The complexity index (fractal dimension D 3D ) exhibits stronger correlation with strength than other metrics, demonstrating its greater sensitivity in capturing the structure features across diverse hydrochemical environments. Three dominant micromechanisms, including clay swelling-shrinkage, mineral dissolution/hydrolysis, and salt leaching & exchange, exert distinct patterns of structure deterioration.