Experimental Study on Wetting Deformation of Rockfill Materials under Different Stress Paths

The collapse settlement induced by wetting deformation during the impounding period has a significant impact on the safety of rockfill dams. Previous large-scale triaxial wetting investigations on rockfill have predominantly been conducted under the conventional triaxial compression (CTC) path, leaving the effects of different loading stress paths on the wetting deformation behavior uncertain. To address this, large-scale triaxial tests were conducted to investigate the wetting deformation of rockfill materials under both the CTC and constant stress ratio (CSR) paths. The results indicated that wetting deformation was not only related to the stress state but also to the previous loading path. At a low stress ratio (eta=0.70), wetting deformation was more pronounced when subjected to the CTC path than the CSR path. However, as the stress ratio increased to higher levels (eta=1.20 and 1.50), the wetting deformation under the CSR path surpassed that under the CTC path. Furthermore, it observed that the wetting deformation under different loading paths was proportional to the plastic work before wetting. Given the limitation of previous wetting strain models that only considered the stress state, a novel wetting strain model to evaluate the wetting deformation of rockfill is proposed, eliminating the impact of loading stress paths by introducing plastic work. The simulation results demonstrated good agreement with the observed wetting deformation under both the CTC and CSR paths.