Insights into the mechanism of earthquake-triggered landslides in plastic fine-grained soils

This article seeks to investigate the cyclic behaviour of fine-grained soils and clarify the mechanism of earthquake-triggered landslides in this material. Six soils with different plasticity and mineralogy were tested in a series of undrained ring-shear experiments using different stress histories. The obtained results were analyzed in relation to the soil plasticity, clay mineralogy, and soil microfabrics to better understand the main factors leading to failure. It was found that the low-plasticity soil mixtures containing either kaolinite or illite were susceptible to liquefaction, while more plastic soil specimens that contained smectite were resistant to liquefaction. The mechanism of earthquake-triggered landslides and the factors affecting them were discussed, and it was experimentally shown that the failure in plastic fine-grained soils was not driven by the excess pore water pressure. Instead, it occurred mostly due to the large permanent shear displacements developed during cyclic loading.