Abstract
The internal friction angle of soils mobilized during the motion of landslides is the most important factor for the prediction of landslide motion. However, this will be not the same with the internal friction angle obtained from the conventional (almost static) shear tests, because the speed and displacement of shearing used in the conventional shear tests are quite different from those in moving landslides.
Using a new high speed ring shear apparatus, the internal friction angle of granular materials was measured by changing normal stress through the continual shearing at a constant shear speed of 0.01-100cm/sec, under the dry or the drained condition. The friction angle in the tested materials did not change so much, but varied from -3.2° to + 3.7°at different shear speed of 0.01cm/sec-100cm/sec, and the sense of difference of friction angle was not the same in materials. Possible mechanisms to interpret the variation of the internal friction angle during motion were discussed.
