ABSTRACT
Run-out distances of granular mass flows were investigated by means of large-scale flume tests for pumiceous gravel, and a mixture of pumiceous gravel and volcanic ash. In flow-type landslides, liquefaction may play a major role in the rapid velocity and long run-out distance. Once the liquefaction occurs, the soil particles in the soil layers may float due to the excess of pore-fluid pressure and the subsequent loss of effective normal stress. R. A. Bagnold proposed the grain flow model which pays particular attention to the phenomena taking place in the granular mass flows. In this model, the soil particles were well dispersed due to the mutual collisions and the resulting smaller frictional resistance. One side of the flume was covered by reinforced glass, making it possible to film the movement of centres of gravity of the granular mass flows. Data of laser sensors and pressure transducers were logged by a PC at 100 Hz.
