EXPERIMENTAL STUDY ON MECHANISM OF SHALLOW LOESS LANDSLIDES INDUCED BY RAINFALL

The loess is loose, and contains numerous large pores and vertical joints inside, which provides channels for the rapid infiltration of rainfall. The shallow loess landslides have caused significant casualties and economic losses. In order to effectively reduce the social and economic impact of landslides induced by rainfall, it is of great realistic significance to carry out the laboratory experimental study on rainfall-induced landslides. The purpose of this paper is to study the effects of different rainfall pattern and different slope structure on the deformation and failure process of loess slope. Three groups of indoor physical model experiments are designed and conducted. They include loess slope with continuous heavy rainfall, loess slope containing a vertical joint with continuous heavy rainfall, and loess slope with intermittent heavy rainfall. Three kinds of sensors including volume moisture sensors, matric suction sensors and pore water pressure sensors are buried to record the internal changes in each loess slope. Analyzing the changing readings of sensors and experimental phenomenon, and comparing the experimental procedures and results under the different experimental conditions disclose the deformation and failure law of shallow loess landslide under rainfall condition. The failure mode and triggering mechanism of this kind of landslides are summarized. The experimental results show that, in the early stage of the experiments, the matric suction of the loess decreased gradually and maintained stable in the end, therefore the strength reduced, with the continuous increases of volume moisture. In the later stage, the upper loess of the slope reached the saturation stage, excess pore water pressure generated by the slope deformation and poor drainage of the loess decreased the effective stress and the strength of the loess, and as a result, the strength reached the minimum, which resulted in landslides. And meanwhile, the influence of slope structure on slope stability is greater than that of rainfall pattern.