Abstract
Granular landslides frequently occur in nature. It is of great importance to understand the dynamics of this kind of rapid movement. A series of analogue models are used to investigate the effect of the geometry of an inclined weak horizon on the 3D internal structures of granular slopes. Model results show that the failure of granular slopes results in formation of different-generation failure surfaces in the rear of the failure mass. In model 1 containing a shallowly-located weak horizon with a dip of 45° and a strike of 0°, the main failure surface is located within the weak horizon, and cut across the entire stratigraphy of the slope. In model 2 containing a deeply-located weak horizon with a dip of 45° and a strike of 0°, the main failure surface is also located within the weak horizon, but cut across only the shallow units. In model 3 containing a weak horizon with a dip of 45° and a strike of 15°, the main failure surface is partly located within the weak horizon which is shallowly located, and partly located above the weak horizon which is deeply located. Model results also show that the main failure surfaces differ in amount of displacement they accommodate. Displacement of the main failure surface, which forms within the whole weak horizon, increases with depth. In contrast, displacement of the main failure surface, which forms within the upper part of the weak horizon or above the weak horizon, decreases with depth. In all models, displacement of the failure surface differs along the strike direction. In models containing a weak horizon with a strike of 0°, displacement of the main failure surface increases towards the middle of the slope model, whereas in models containing a weak horizon with a strike of 15°, displacement of the main failure surface increases towards the direction where the weak horizon is shallowly located. The distribution of later-generation failure surfaces within the failure mass is also affected significantly by the geometry of the weak horizon.
