EXPERIMENTAL STUDY ON DEFORMATION AND FAILURE MECHANISM OF SHALLOW LOESS LANDSLIDE UNDER THE EFFECT OF IRRIGATION

In order to effectively reduce the enormous losses to society and economy caused by shallow loess landslides triggered by irrigation in large area of Jingyang, it is of great realistic significance to carry out laboratory experimental study on irrigation-induced landslides and to study the effects of slope gradient on deformation and failure process of loess slope under irrigation condition. Irrigation rig used for slope surface and slope top irrigation was designed. In the meanwhile, two groups of indoor physical model experiments respectively with slope of 45 degrees and slope of 60 degrees were conducted, and three kinds of sensors namely volume moisture sensors, matric suction sensors and pore water pressure sensors were buried inside the slopes to record the internal changes. Based on the analysis and the comparison of the experimental procedures and results of two groups, the deformation and failure law of shallow loess landslide under irrigation condition is disclosed, and the failure mode and the triggering mechanism of this kind of landslides are summarized. The experimental results show that, at the early stage of the experiments, with the continuous increases of volume moisture, the matric suction of the loess decreased gradually and maintained stable in the end while the strength reduced accordingly at the later stage, the upper loess of the slope reached the saturation stage, excess pore water pressure was generated by the slope deformation and poor drainage of the loess, which decreased the effective stress and the strength of the loess. As a result, the strength reached the minimum, which resulted in landslides. And meanwhile, the steeper a slope is, the greater probability of landslide occurrence is, and the smaller the depth of sliding surface and sliding distance are.