Disaster Characteristics and Destructive Mechanism of Typical Loess Landslide Cases Triggered by Human Engineering Activities

In order to reveal the mechanism of loess landslide hazards induced by human engineering activities, typical loess landslide cases were studied using field investigations, physical model tests, and stress path tests. Analyses were made for the formation of shear zones triggered by heap loading, the evolution patterns of loess landslides triggered by unloading, and the development process of loess landslides induced by irrigation. The results show that in loess landslides triggered by heap loading and unloading, vertical joints and cracks easily evolve into a fracture belt. Under the action of shear stresses, shear creep zones expand from the toe to the internal of a slope gradually and develop into shear zones that penetrate the slope, which leads to the overall deformation and failure of slopes. Physical model tests reveal that the loess landslides triggered by heap loading have a typical feature of two sliding zones in shallow and deep layers. The loess landslides triggered by irrigation mainly develop in the loess tableland edge. The long-term irrigation will uplift the groundwater and cause the formation of a saturated zone in the slope body. The creep shear failure then occurs to the slope under the gravity load, resulting in the start of a landslide. In addition, the large-scale fast loading process will cause the liquefaction of the shallow loess in the front section of the slope body, and eventually triggers long-range loess mud flow landslides.