Prediction method of the onset of landslides based on the Stress-Dilatancy relation against shallow landslides

Abstract

The combination of the monitoring of the surface displacement and the creep theory (strain-time relation) of a soil is adopted in practice to predict the time of onset of a shallow landslide. This method sometimes cannot make good prediction because the creep theory cannot treat the change of stress in the slope. Some variant should be necessary for indicating the stress state. The utility of the ratio of the increase of the compression strain to the increase of the shear strain (strain increment ratio) in the slope and the ratio of the increase of the vertical displacement to the increase of the surface displacement (displacement increment ratio) as the stress parameter were examined in this paper based on analysis of the monitoring data of the deformation of the sandy model slope. As results, the strain increment ratio and the displacement increment ratio at deeper soil layer approaches toward zero with the increase of the shear strain or the surface displacement. It means the soil layer approaches the critical (failure) state. These facts show that the strain increment ratio and the displacement increment ratio can express instability of the slope.