Comparative analysis on the damage properties of the Ili loess under dry-wet and freeze-thaw cycles

Zizhao Zhang ^* Yang HU ^* Qianli Lv Ruihua Hao Guobin Tang

• Xinjiang University, Urumqi, China

The structural integrity of slopes in the Ili valley is critically influenced by the inherent characteristics of loess, in particular when it is subjected to the seasonal climate changes. In the present research, a series of triaxial shear tests were carried out to examine the mechanical behaviour of the Ili loess under different dry-wet and frost thaw cycles. In parallel, some testing methods, including the Scanning Electron Microscopy (SEM) and Nuclear Magnetic Resonance (NMR), were applied to investigate the progressive damage characteristics and the alterations in terms of the micro-structures. Test results demonstrated a strong correlation between the macroscopic mechanical resistance and micro-structural changes of the Ili loess subjected to the dry-wet and freeze-thaw cycles. The impact of the freeze-thaw cycles was more pronounced compared to other parameters, when the reduction in shear strength of the Ili loess under dry-wet cycles was accounted for. The results also showed that either the cohesion or the internal friction angle are much different from each other. Furthermore, changes in terms of the microstructure, such as the particle size, porosity,morphology, soil structure,and particle contact mode, exhibited the distinct characteristics under varying climates. The research outcomes obtained from this research do offer valuable data reference and theoretical guidelines to prevent or postpone the occurrence of the landslide in the Ili valley under critical environmental conditions.