Influence of fine soil particles on excess of basal pore-fluid pressure generation in granular mass flows

摘要

Run-out distances of granular mass flows were investigated by means of large-scale flume testsfor pumiceous gravel,and a mixture of pumiceous gravel and volcanic ash. The tests with narrowing and abruptchange in the inflow angle of the horizontal segment produced the smaller run-out distances for the pumiceousgravel sample,in which no excess of pore-fluid pressure was generated. On the other hand,an excess of pore-fluid pressure was generated in the mixture of pumiceous gravel and volcanic ash. This was likely because ofthe quasi-undrained shear deformation due to the low permeability of the mixture and the suspensions of thefiner particles flowed in the pore-fluid. The mixture sample passed through the narrowing smoothly and traveledlonger distance. This could be because less frictional resistance was generated in the mixture due to the loweringof effective stress between soil particles associated with the excess pore-fluid pressure.