Abstract

Most landslides on the Loess Tableland (Shaanxi, China) are of the sliding-flow type, with long run-out distances. These landslides, which tend to be triggered by irrigation, result in loss of life and damage to infrastructure. In order to reveal the characteristics and mechanisms of sliding-flow landslides, field investigations, surveys and indoor tests, including consolidated undrained triaxial tests and ring-shear tests, were conducted. The apparent friction of sliding-flow loess landslides triggered by irrigation in the study area ranged from 0.01 to 0.25, with a mean of 0.159. These values are lower than those associated with the landslides triggered by the Wenchuan Earthquake. The deviation stress decreased to about 99% of its peak value, while the path of the effective stress revealed that the effective normal stress approached zero. Consequently, saturated loess samples were highly liquefiable under consolidated undrained triaxial tests. The pore pressures increased sharply and up to their peak value (mean of 130 kPa), corresponding to 92% of the applied normal stress. The path of effective stress did not reach the failure line. The loose structure and macro-pore content of loess provide the framework for static liquefaction to occur as a consequence of the generation of fine particles.

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