Study of the Mechanics of Debris Flow and its Simulation Model

抄録

The behavior of sediment accompanying the collapse of mountainsides was examined as part of a study of the mass flow of sediment and water, which is represented by debris flow. In connection with the behaviour of collapsing sediment, the following equation expresses the applicable resistance law in the case of dry sand.
τ=τ_y+τ_g
where, τ_y: Yield stress, τ_g: Force resulting from the non-elastic collision between grains.
The authors derived the equations for the velocity distribution in the vertical direction and the mean velocity of the mass flow of dry sand from the resistance law mentioned above by making use of Bagnold's grain arrangement model. The velocity distribution thus obtained was evaluated through flow tests of dry sand. Moreover, a numerical simulation model of the flow and sedimentation of collapsing sediment was created by making use of the resistance law mentioned above. This simulation model was compared with flow and deposition tests of dry sand carried out in two-dimensional waterways with the object of verifying its appropriateness.